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Sample records for basalt coarse aggregates

  1. Radiation shielding concrete made of Basalt aggregates.

    Science.gov (United States)

    Alhajali, S; Yousef, S; Kanbour, M; Naoum, B

    2013-04-01

    In spite of the fact that Basalt is a widespread type of rock, there is very little available information on using it as aggregates for concrete radiation shielding. This paper investigates the possibility of using Basalt for the aforementioned purpose. The results have shown that Basalt could be used successfully for preparing radiation shielding concrete, but some attention should be paid to the choice of the suitable types of Basalt and for the neutron activation problem that could arise in the concrete shield.

  2. Recycled Coarse Aggregate Produced by Pulsed Discharge in Water

    Science.gov (United States)

    Namihira, Takao; Shigeishi, Mitsuhiro; Nakashima, Kazuyuki; Murakami, Akira; Kuroki, Kaori; Kiyan, Tsuyoshi; Tomoda, Yuichi; Sakugawa, Takashi; Katsuki, Sunao; Akiyama, Hidenori; Ohtsu, Masayasu

    In Japan, the recycling ratio of concrete scraps has been kept over 98 % after the Law for the Recycling of Construction Materials was enforced in 2000. In the present, most of concrete scraps were recycled as the Lower Subbase Course Material. On the other hand, it is predicted to be difficult to keep this higher recycling ratio in the near future because concrete scraps increase rapidly and would reach to over 3 times of present situation in 2010. In addition, the demand of concrete scraps as the Lower Subbase Course Material has been decreased. Therefore, new way to reuse concrete scraps must be developed. Concrete scraps normally consist of 70 % of coarse aggregate, 19 % of water and 11 % of cement. To obtain the higher recycling ratio, the higher recycling ratio of coarse aggregate is desired. In this paper, a new method for recycling coarse aggregate from concrete scraps has been developed and demonstrated. The system includes a Marx generator and a point to hemisphere mesh electrode immersed in water. In the demonstration, the test piece of concrete scrap was located between the electrodes and was treated by the pulsed discharge. After discharge treatment of test piece, the recycling coarse aggregates were evaluated under JIS and TS and had enough quality for utilization as the coarse aggregate.

  3. Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

    Directory of Open Access Journals (Sweden)

    al-Swaidani Aref M.

    2015-11-01

    Full Text Available The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction. Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289 and accelerated mortar bar test (ASTM C1260 have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida’a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete.

  4. Chemical-mineralogical characterisation of coarse recycled concrete aggregate.

    Science.gov (United States)

    Limbachiya, M C; Marrocchino, E; Koulouris, A

    2007-01-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO2, Al2O3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO2 and increase in Al2O3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition.

  5. Chemical-mineralogical characterisation of coarse recycled concrete aggregate.

    Science.gov (United States)

    Limbachiya, M C; Marrocchino, E; Koulouris, A

    2007-01-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO2, Al2O3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO2 and increase in Al2O3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition. PMID:16574393

  6. Performance of Recycled Asphalt Pavement as Coarse Aggregate in Concrete

    Directory of Open Access Journals (Sweden)

    Fidelis O. OKAFOR

    2010-12-01

    Full Text Available Recycled asphalt pavement (RAP is the reclaimed and reprocessed pavement material containing asphalt and aggregate. Most RAP is recycled back into pavements, and as a result there is a general lack of data pertaining to the mechanical properties for RAP in other possible applications such as Portland cement concrete. In the present study, some mechanical properties of Portland cement concrete containing RAP as coarse aggregate were investigated in the laboratory. Six concrete mixes of widely differing water/cement ratios and mix proportions were made using RAP as coarse aggregate. The properties tested include the physical properties of the RAP aggregate, the compressive and flexural strengths of the concrete. These properties were compared with those of similar concretes made with natural gravel aggregate. Results of the tests suggest that the strength of concrete made from RAP is dependent on the bond strength of the “asphalt-mortar” (asphalt binder-sand-filler matrix coatings on the aggregates and may not produce concrete with compressive strength above 25 MPa. However, for middle and low strength concrete, the material was found to compare favorably with natural gravel aggregate.

  7. Use Of Crushed Bricks As Coarse Aggregate In Concrete

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    Fadia S. Kalak

    2013-05-01

    Full Text Available The investigation reported in this paper is carried out to study the feasibility of using crushed bricks to substitute the coarse aggregate (gravel in concrete. Two types of concrete mixing are prepared. The first one is a mixture of  1:2:4 without crushed bricks and is used as a reference mixture .The second one is made of different weight of crushed bricks (as a percentage from the weight of the coarse aggregate. A total of 30 numbers of concrete specimens are casted with and without crushed bricks and  tested under compression and split tension as per relevant to British standard specifications.Test results indicated that using crushed bricks reduces the strength of concrete. Also, the percentage of water to cement ratio increases for constant slump when the percentage of crushed bricks increased.

  8. Acid Resistance of Concrete Containing Laterite Aggregate as Partial Coarse Aggregate Replacement

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    K. Muthusamy

    2014-05-01

    Full Text Available In Malaysia, issues of granite aggregate depletion in future due to increasing use in concrete industry and the availability of laterite aggregate locally has initiated studies on concrete produced using laterite aggregate as partial coarse aggregate replacement. Although, replacement of laterite aggregate up to 30% able to produce concrete with the targeted strength but durability of this concrete towards acid attack yet to be investigated. Thus, this study presents and discusses the performance of concrete consisting various percentage of laterite aggregate integrated as partial coarse aggregate replacement upon exposure to acidic environment. Mixes consisting various content of laterite aggregate as partial coarse aggregate replacement ranging from 0, 10, 20, 30, 40 and 50%, respectively were prepared in form of cubes and then subjected to water curing for 28 days before immersed in hydrochloric acid solution for 1800 h. Performance of the specimens were observed through mass loss and strength reduction. Generally, durability performance of concrete produced using up to 20% of laterite aggregate is comparable to plain concrete.

  9. Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties

    OpenAIRE

    Neeraj Jain; Mridul Garg; Minocha, A. K.

    2015-01-01

    Present investigations deal with the development of green concrete (M 30 grade) using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100%) with recycled coarse aggregate on various mechanical ...

  10. Ceramic ware waste as coarse aggregate for structural concrete production.

    Science.gov (United States)

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste. PMID:25188783

  11. Ceramic ware waste as coarse aggregate for structural concrete production.

    Science.gov (United States)

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

  12. Properties of Self-Compacting Concrete with Recycled Coarse Aggregate

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    W. C. Tang

    2016-01-01

    Full Text Available The utilisation of recycled concrete aggregate (RCA in Self-Compacting Concrete (SCC has the potential to reduce both the environmental impact and financial cost associated with this increasingly popular concrete type. However, to date limited research exists exploring the use of coarse RCA in SCC. The work presented in this paper seeks to build on the existing knowledge in this area by examining the workability, strength, and fracture properties of SCCs containing 0%, 25%, 50%, 75%, and 100% coarse RCA. The experimental programme indicated that at RCA utilisation levels of 25% to 50% little or no negative impact was observed for strength, workability, or fracture properties, with the exception of a slight reduction in Young’s modulus.

  13. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

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    Gideon Siringi

    2015-01-01

    Full Text Available Tire derived aggregate (TDA has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

  14. Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

    Science.gov (United States)

    Salau, M. A.; Oseafiana, O. J.; Oyegoke, T. O.

    2015-11-01

    This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.

  15. Ballistic impact response of a coarse-aggregate barrier

    International Nuclear Information System (INIS)

    The physical understanding of the damage inflicted to a protective barrier resulting from impact with a projectile is paramount to the intelligent design of advanced protective systems. The configuration of the protective barrier used for ballistic impact studies depends upon the overall protective device that the barrier is to represent. Although many barriers are homogeneous in configuration, a much broader class of barriers involves a non-uniform agglomeration of components. Such barriers can conceivably represent the means of protection for ammunition bunkers, nuclear reactors, armored military vehicles, or any asset for which protection against projectile impact is desired. Here, an experiment-oriented investigation aimed at gaining insight and understanding of the physical phenomena that occur when a projectile impacts a thin barrier consisting of a uniform, coarse aggregate was performed at the US Army Research Laboratory. The thin barrier target was an assembly of solid steel cylinders oriented in a 15-by-15 rod square-packed array. The projectile consisted of a solid aluminum cylinder with a diameter of approximately 2.5 aggregate diameters and a length of 1.25 aggregate element lengths. The impact velocity was 2 km/s. The data collected consisted of the crater size in the barrier, plastic deformation of individual cylinders, a lateral damage wave velocity from the strain gage signals, and the residual penetrator length. A detailed analysis of the damage inflicted on the aggregate elements of the barrier was performed. The analysis focused primarily on the steel cylinders that resided outside of the eroded crater zone. Iso-strain contours were mapped on the face of the barrier to shed insight into the contact mechanics of the individual aggregate elements. A semi-empirical aggregate deformation model was created to predict the magnitude of deformation that occurs to cylinders located outside the physical crater

  16. Behaviour of Recycled Coarse Aggregate Concrete: Age and Successive Recycling

    Science.gov (United States)

    Sahoo, Kirtikanta; Pathappilly, Robin Davis; Sarkar, Pradip

    2016-06-01

    Recycled Coarse Aggregate (RCA) concrete construction technique can be called as `green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio ( w/ c). The present work is an attempt to study the behaviour of RCA concrete from two samples of parent concrete having different age group with regard to the relationship of compressive strength with water cement ratios. Number of recycling may influence the mechanical properties of RCA concrete. The influence of age and successive recycling on the properties such as capillary water absorption, drying shrinkage strain, air content, flexural strength and tensile splitting strength of the RCA concrete are examined. The relationship between compressive strength at different w/ c ratios obtained experimentally is investigated for the two parameters such as age of parent concrete and successive recycling. The recycled concrete using older recycled aggregate shows poor quality. While the compressive strength reduces with successive recycling gradually, the capillary water absorption increases abruptly, which leads to the conclusion that further recycling may not be advisable.

  17. Structural Concrete Prepared with Coarse Recycled Concrete Aggregate: From Investigation to Design

    OpenAIRE

    Valeria Corinaldesi

    2011-01-01

    An investigation of mechanical behaviour and elastic properties of recycled aggregate concrete (RAC) is presented. RACs were prepared by using a coarse aggregate fraction made of recycled concrete coming from a recycling plant in which rubble from concrete structure demolition is collected and suitably treated. Several concrete mixtures were prepared by using either the only virgin aggregates (as reference) or 30% coarse recycled aggregate replacing gravel and by using two different kinds of ...

  18. THE EFFECT OF DIFFERENT STEEL FIBERS SIZE WITH PRE-SETTING PRESSURE ON BASALT AGGREGATE CREATED USING THE REACTYVE POWDER CONCRETE

    OpenAIRE

    İpek, Metin

    2011-01-01

    In this study, the coarse aggregate (basalt aggregate) is created using the reactive powder concrete (RPB) with different fiber content, size and cost of compression pressure was investigated. The mixture composition, which would present the best performance during the flexural tests, was determined. Pre-setting pressure tests at six different magnitudes (0, 5, 10, 15, 20, 25 MPa) were conducted on the freshly prepared RPB having the determined mixture composition. The 30 mm long steel fibers...

  19. Basalt fiber reinforced porous aggregates-geopolymer based cellular material

    Science.gov (United States)

    Luo, Xin; Xu, Jin-Yu; Li, Weimin

    2015-09-01

    Basalt fiber reinforced porous aggregates-geopolymer based cellular material (BFRPGCM) was prepared. The stress-strain curve has been worked out. The ideal energy-absorbing efficiency has been analyzed and the application prospect has been explored. The results show the following: fiber reinforced cellular material has successively sized pore structures; the stress-strain curve has two stages: elastic stage and yielding plateau stage; the greatest value of the ideal energy-absorbing efficiency of BFRPGCM is 89.11%, which suggests BFRPGCM has excellent energy-absorbing property. Thus, it can be seen that BFRPGCM is easy and simple to make, has high plasticity, low density and excellent energy-absorbing features. So, BFRPGCM is a promising energy-absorbing material used especially in civil defense engineering.

  20. Geo-engineering evaluation of Termaber basalt rock mass for crushed stone aggregate and building stone from Central Ethiopia

    Science.gov (United States)

    Engidasew, Tesfaye Asresahagne; Barbieri, Giulio

    2014-11-01

    The geology of the central part of Ethiopia exhibits a variety of rock types that can potentially be developed for construction stone production, of which the most wide spread and important one is the Termaber basalt. Even though some preliminary work is done on these rocks towards construction material application, it remains largely that this resource is untouched and needs further scientific characterization for the use in large scale industrial application. Basaltic rocks have been widely used in many parts of the world as concrete aggregate and dimension stone for various civil structures. The present research study was carried out for Geo-engineering evaluation of Termaber basalt rock mass for crushed stone aggregate and building stone from Central Ethiopia (around Debre Birhan). The main objective of the present research study was to assess the general suitability of the Termaber basalt to be used as coarse aggregate for concrete mix and/or to utilize it as cut stone at industrial level. Only choice made with full knowledge of the basic characteristics of the material, of its performance and durability against the foreseen solicitations will ensure the necessary quality of the stone work and thereby a possibility to reach its intended service life. In order to meet out the objective of the present study, data from both field and laboratory were collected and analyzed. The field data included geological investigations based on different methods and sample collection while the laboratory work included, uniaxial compressive strength, ultrasonic pulse velocity, dynamic elasticity modulus, bulk density, water absorption, specific gravity, open porosity, aggregate impact value, petrographic examination and XRF, aggregate crushing value, Los Angeles abrasion value, sodium sulfate soundness, X-ray diffraction and alkali silica reactivity tests. The field and laboratory data were compiled and compared together to reveal the engineering performance of the rock mass in

  1. Generic Coarse-Grained Model for Protein Folding and Aggregation

    Science.gov (United States)

    Bereau, Tristan; Deserno, Markus

    2009-03-01

    The complexity involved in protein structure is not only due to the rich variety of amino acids, but also the inherent weak interactions, comparable to thermal energy, and important cooperative phenomena. This presents a challenge in atomistic simulations, as it is associated with high-dimensionality and ruggedness of the energy landscape as well as long equilibration times. We have recently developed a coarse-grained (CG) implicit solvent peptide model which has been designed to reproduce key consequences of the abovementioned weak interactions. Its intermediate level of resolution, four beads per amino acid, allows for accurate sampling of local conformations by designing a force field that relies on simple interactions. A realistic ratio of α-helix to β-sheet content is achieved by mimicking a nearest-neighbor dipole interaction. We tune the model in order to fold helical proteins while systematically comparing the structure with NMR data. Very good agreement is achieved for proteins that have simple tertiary structures. We further probe the effects of cooperativity between amino acids by looking at peptide aggregation, where hydrophobic peptide fragments cooperatively form large-scale β-sheet structures. The model is able to reproduce features from atomistic simulations on a qualitative basis.

  2. A Study of Concrete Made with Fine and Coarse Aggregates Recycled from Fresh Concrete Waste

    OpenAIRE

    Mamery Sérifou; Sbartaï, Z. M.; S. Yotte; Boffoué, M. O.; Emeruwa, E.; Bos, F

    2013-01-01

    This paper deals with the possibility of using fresh concrete waste as recycled aggregates in concrete. An experimental program based on two variables (proportion of fine aggregates replacement and proportion of coarse aggregates replacement) was implemented. The proportions of replacement were 0%, 50%, and 100% by mass of aggregates. Several mechanical properties were tested as compressive and tensile strengths. The results show a good correlation between aggregates replacement percentage an...

  3. Investigation of Coarse Aggregate Strength for Use in Stone Matrix Asphalt

    OpenAIRE

    Celaya, Brandon J.; Haddock, John E.

    2006-01-01

    Stone Matrix Asphalt is a gap-graded hot-mix asphalt mixture composed of a coarse aggregate skeleton and a binder-rich mortar. The mixture type was first introduced to the United States in 1991, with one of the first test sections placed on I-70 near Richmond, Indiana. To help control the selection of coarse aggregate, the Indiana Department of Transportation specified a maximum Los Angeles Abrasion loss value of 30 percent. An investigation into the coarse aggregate specifications for use in...

  4. Mechanical Characteristic of Pervious Concrete Considering the Gradation and Size of Coarse Aggregates

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    Alireza Joshaghani

    2014-09-01

    Full Text Available Pervious concrete is a kind of sustainable pavement with high permeability which is becoming more common as a storm water management. The purpose of this study was to investigate the effects of coarse aggregate on physical and mechanical properties of the pervious concrete such as density, strength, porosity and permeability at 7, 28, 56 days. This experimental investigation conducted by comparing nine different mixtures. Taguchi design of experiments used to optimize the performance of these characteristics. To test the influence of aggregate systematically, water to cement ratio (w/c, paste content and coarse aggregate size were kept constant at 3 levels. 9.5, 12.5 and 19.0 mm were used for maximum aggregate sizes. The relationship between strength and porosity for pervious concrete are found to be dependent on coarse aggregate size. The test results demonstrated when the maximum size of the coarse aggregate increased, the strength decreases and the permeability and porosity grows up. An increased aggregate amount resulted in a significant decrease in compressive strength due to the subsequent decrease in paste amount. Age and coarse aggregate size had effect on the pervious concrete characteristic. To meet the specification requirements in the mix design of pervious concrete, considering both compressive strength and permeability is necessary. Finally, a parametric study is conducted to investigate the influence of design factors on the properties of porous concrete. The general equations for pervious concrete are related to compressive strength and void ratio for different aggregate sizes.

  5. Influence of water absorption of coarse recycled concrete aggregates on the performance of concrete

    OpenAIRE

    Joseph, Miquel

    2014-01-01

    The “ValReCon20 program” has proven the possibility to replace up to 100% of the coarse virgin aggregates by coarse recycled concrete aggregates (CRCA) in concrete of strength class C25/30. At this moment most uncertainties about recycled concrete concern durability in aggressive environments. This PHD researches destructive mechanisms that use water as transportation for harmful reagents. The physical phenomenon that describes water transportation is known as “Water Permeability” This is...

  6. Exploratory Study of Rubber Seed Shell as Partial Coarse Aggregate Replacement in Concrete

    OpenAIRE

    K. Muthusamy; Nordin, N.; G. Vesuvapateran; M. Ali; N.A. Mohd Annual; H. Harun; H. Ullap

    2014-01-01

    Malaysia being a major rubber trees growing country has been generating a large amount of rubber seed shell which regarded as waste. At the same time, the growing construction industry which boosts the concrete production trade has results in higher consumption of natural coarse aggregate which open the door for depletion of this material in future. This study focuses on investigating the possibility of integrating crushed rubber seed shell as partial coarse aggregate replacement material in ...

  7. Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties

    Directory of Open Access Journals (Sweden)

    Neeraj Jain

    2015-01-01

    Full Text Available Present investigations deal with the development of green concrete (M 30 grade using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100% with recycled coarse aggregate on various mechanical and durability properties of hardened concrete were discussed and compared with controls at different w/c ratio. Improvements in all the engineering properties of hardened concrete were observed using washed recycled coarse aggregates. The compressive strength of 28-day hardened concrete containing 100% washed recycled aggregate was slightly lower (7% than concrete prepared with natural aggregates. Water absorption, carbonation, and rapid chloride penetration test were conducted to assess the durability of the concrete. Concrete was found moderately permeable for chloride ions penetration and no carbonation was observed in all the concrete mixes studied.

  8. A Study of Concrete Made with Fine and Coarse Aggregates Recycled from Fresh Concrete Waste

    Directory of Open Access Journals (Sweden)

    Mamery Sérifou

    2013-01-01

    Full Text Available This paper deals with the possibility of using fresh concrete waste as recycled aggregates in concrete. An experimental program based on two variables (proportion of fine aggregates replacement and proportion of coarse aggregates replacement was implemented. The proportions of replacement were 0%, 50%, and 100% by mass of aggregates. Several mechanical properties were tested as compressive and tensile strengths. The results show a good correlation between aggregates replacement percentage and concrete properties. Concerning mechanical properties, a gradual decrease in compressive, splitting, and flexural strengthn with the increase in recycled aggregate percentage is shown.

  9. The Dependence of Physical Mechanical Properties of Concrete Pavement Blocks on Coarse Aggregate Type

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    Malaiškienė Jurgita

    2014-12-01

    Full Text Available The aim of this research is to determine the dependences of the physical mechanical properties of vibropressed concrete (pavement blocks on the type of coarse aggregate used in the main layer. Sustainability of concrete pavement blocks is a really important matter. Five different batches of pavement blocks were produced, changing the consistence ratio of coarse aggregate in the main layer. There are two types of course aggregate: crushed gravel and granite. The consistence of a facing layer was not changed. All tests: density, tensile split strength, water absorption for vibro-pressed concrete units were made according to EN 1338:2003+AC2006.

  10. Use of Steel Slag as Coarse Aggregate for the Production of Pervious Concrete

    OpenAIRE

    Georgia Vardaka; Kiriakos Thomaidis; Christos Leptokaridis; Stamatis Tsimas

    2014-01-01

    Pervious concrete is a type of concrete with significantly increased water permeability, ensuring increased rates of drainage of rainfall. The high porosity is achieved by removing a large percentage of fine aggregates from the mix. The present paper is an approach for the addition of steel slag as a substitute for coarse aggregates in pervious concrete. More specifically, three types of aggregates have been used: steel slag, construction and demolition wastes and conventional limestone aggre...

  11. Shear behavior of coarse aggregates for dam construction under varied stress paths

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    Liu Hanlong

    2008-03-01

    Full Text Available Coarse aggregates are the major infrastructure materials of concrete-faced rock-fill dams and are consolidated to bear upper and lateral loads. With the increase of dam height, high confining pressure and complex stress states complicate the shear behavior of coarse aggregates, and thus impede the high dam's proper construction, operation and maintenance. An experimental program was conducted to study the shear behavior of dam coarse aggregates using a large-scale triaxial shear apparatus. Through triaxial shear tests, the strain-stress behaviors of aggregates were observed under constant confining pressures: 300 kPa, 600 kPa, 900 kPa and 1200 kPa. Shear strengths and aggregate breakage characteristics associated with high pressure shear processes are discussed. Stress path tests were conducted to observe and analyze coarse aggregate response under complex stress states. In triaxial shear tests, it was found that peak deviator stresses increase along with confining pressures, whereas the peak principal stress ratios decrease as confining pressures increase. With increasing confining pressures, the dilation decreases and the contraction eventually prevails. Initial strength parameters (Poisson’s ratio and tangent modulus show a nonlinear relationship with confining pressures when the pressures are relatively low. Shear strength parameters decrease with increasing confining pressures. The failure envelope lines are convex curves, with clear curvature under low confining pressures. Under moderate confining pressures, dilation is offset by particle breakage. Under high confining pressures, dilation disappears.

  12. Effect of Different Coarse Aggregate Sizes on the Strength Characteristics of Laterized Concrete

    Science.gov (United States)

    Salau, M. A.; Busari, A. O.

    2015-11-01

    The high cost of conventional concrete materials is a major factor affecting housing delivery in developing countries such as Nigeria. Since Nigeria is blessed with abundant locally available materials like laterite, researchers have conducted comprehensive studies on the use of laterite to replace river sand partially or fully in the concrete. However, the works did not consider the optimum use of coarse aggregate to possibly improve the strength of the laterized concrete, since it is normally lower than that of normal concrete. The results of the tests showed that workability, density and compressive strength at constant water-cement ratio increase with the increase in the coarse aggregate particle size and also with curing age. As the percentage of laterite increases, there was a reduction in all these characteristics even with the particle size of coarse aggregate reduction due to loss from the aggregate-paste interface zone. Also, when sand was replaced by 25% of laterite, the 19.5mm and 12.5mm coarse aggregate particle sizes gave satisfactory results in terms of workability and compressive strength respectively at 28 days of curing age, compared to normal concrete. However, in case of 50% up to 100% laterite contents, the workability and compressive strength values were very low.

  13. Structural Concrete Prepared with Coarse Recycled Concrete Aggregate: From Investigation to Design

    Directory of Open Access Journals (Sweden)

    Valeria Corinaldesi

    2011-01-01

    Full Text Available An investigation of mechanical behaviour and elastic properties of recycled aggregate concrete (RAC is presented. RACs were prepared by using a coarse aggregate fraction made of recycled concrete coming from a recycling plant in which rubble from concrete structure demolition is collected and suitably treated. Several concrete mixtures were prepared by using either the only virgin aggregates (as reference or 30% coarse recycled aggregate replacing gravel and by using two different kinds of cement. Different water-to-cement ratios were adopted ranging from 0.40 to 0.60. Concrete workability was always in the range 190–200 mm. Concrete compressive strength, elastic modulus, and drying shrinkage were evaluated. Results obtained showed that structural concrete up to C32/40 strength class can be manufactured with RAC. Moreover, results obtained from experimentation were discussed in order to obtain useful information for RAC structure design, particularly in terms of elastic modulus and drying shrinkage prediction.

  14. Granular Effect of Fly Ash Repairs Damage of Recycled Coarse Aggregate

    Institute of Scientific and Technical Information of China (English)

    LI Jiu-su; XIAO Han-ning; GONG Jian-qing

    2008-01-01

    Repairing effect of fly ash (FA) on damage of recycled coarse aggregate was evaluated by characteristics of pores and cracks in the vicinity of interracial transition zone (ITZ). The interracial structure between the virgin aggregate and the attached old mortar was investigated and compared with ITZ of recycled aggregate concrete in the presence of FA or ultra-fine FA(UFA) by means of scanning electron microscope (SEM). Diam- eter and plumpness frequency distribution of pores as well as width of the old ITZ, length of contacting points and cracks density were analyzed. The SEM results reveal that the diameter of pores is decreases significantly but pores plumpness increases. A decreased ITZ width and cracks density as well as an increased bonding zone length can also been observed, which indicates that FA or UFA repairs damage of recycled coarse aggregate due to its granular effect.

  15. Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

    Directory of Open Access Journals (Sweden)

    Escadeillas G.

    2010-06-01

    Full Text Available This paper examines the influence of coarse aggregate characteristics on the time-dependent deformations of High Performances Concretes (HPC. Four concretes made using the same cement paste but incorporating different types of aggregate (rolled siliceous gravel, crushed granite, crushed limestone and crushed siliceous gravels were studied in order to investigate the effect of aggregate properties on the compressive strength, modulus of elasticity, shrinkage and creep. The results indicate that the aggregate type has a significant effect on creep and shrinkage deformations of HPC. An influence of the shape of aggregate on time-dependent deformations has also been observed. On the basis of these results, long-term behaviour seems to be correlated to the characteristics of the Interfacial Transition Zone (ITZ strongly depending on the mineralogical nature and properties of aggregates. The experimental results are compared with the values calculated using the current Eurocode 2 model in order to assess the accuracy of the predictions.

  16. Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

    Science.gov (United States)

    Makani, A.; Vidal, T.; Pons, G.; Escadeillas, G.

    2010-06-01

    This paper examines the influence of coarse aggregate characteristics on the time-dependent deformations of High Performances Concretes (HPC). Four concretes made using the same cement paste but incorporating different types of aggregate (rolled siliceous gravel, crushed granite, crushed limestone and crushed siliceous gravels) were studied in order to investigate the effect of aggregate properties on the compressive strength, modulus of elasticity, shrinkage and creep. The results indicate that the aggregate type has a significant effect on creep and shrinkage deformations of HPC. An influence of the shape of aggregate on time-dependent deformations has also been observed. On the basis of these results, long-term behaviour seems to be correlated to the characteristics of the Interfacial Transition Zone (ITZ) strongly depending on the mineralogical nature and properties of aggregates. The experimental results are compared with the values calculated using the current Eurocode 2 model in order to assess the accuracy of the predictions.

  17. Aggregation based on graph matching and inexact coarse grid solve for algebraic multigrid

    CERN Document Server

    Kumar, Pawan

    2011-01-01

    A graph based matching is used to construct aggregation for algebraic multigrid. Effects of inexact coarse grid solve is analyzed numerically for a highly discontinuous convection diffusion coefficient matrix and problems from Florida matrix market collection. The proposed strategy is found to be more robust compared to a classical AMG approach.

  18. Laboratory Investigation Of Partial Replacement Of Coarse Aggregate By Plastic Chips And Cement By Human Hair

    Directory of Open Access Journals (Sweden)

    A.S.Balaji

    2014-04-01

    Full Text Available The use of plastic is increasing day by day, although steps were taken to reduce its consumption. The suitability of recycled plastics as coarse aggregate in concrete and its advantage are discussed here. Experimental investigation was done using M20 mix and tests were carried out as per recommended procedures by relevant codes. As 100% replacement of natural coarse aggregate (NCA with plastic coarse aggregate (PCA is not feasible, partial replacement were examined. And also Hair is used as a fibred reinforcing material in concrete as partial replacement of cement. It has a high tensile strength which is equal to that of a copper wire with similar diameter. It is also available in abundance and at a very low cost. Tests were conducted to determine the properties of plastic aggregate and human hair such as density, specific gravity and crushing value. Experiments were conducted on concrete cubes with various percentages of human hair i.e. 0%, 0.5%, 1%, 1.5%, 2%, and 3% by weight of cement and with constant percentage of plastic aggregate as 20%.

  19. Performance Degradation of the Repeated Recycled Aggregate Concrete with 70% Replacement of Three-generation Recycled Coarse Aggregate

    Institute of Scientific and Technical Information of China (English)

    ZHU Pinghua; ZHANG Xinxin; WU Junyong; WANG Xinjie

    2016-01-01

    The feasibility of using different generations recycled coarse aggregate (RCA) on structural concrete was fully evaluated by studying the performance of the recycled coarse aggregates and their corresponding concretes, the different generations of RCA were recycled by following the repeated mode of ‘concrete-waste concrete-coarse aggregate-concrete’. Moreover, the focus was on ‘three generations’ of repeated RCAs, the RCA was produced by crushing and regenerating the artiifcial accelerated degraded concrete, the process was designed to follow the nature degradation of the concrete with a coupling action of accelerated carbonation and bending load. The properties ofx-generation (x=1, 2 or 3) of repeated RCA were systematically investigated and the compressive and splitting tensile strengths of relating structural concretes(with 70% replacement ofx-generation of RCA) were studied accordingly. The results show a competent compressive and splitting tensile strength of 30 MPa at 28th day of structural concretes with all generations of repeated RAC. And the gradual degraded performance of the repeated RCAs was observed with an increased numbers of repetition (1﹥2﹥3 generations), the overall performances of all repeated RCAs fulifll the ClassⅢaccording to Chinese Standards GB25177-2010. Our gained insight demonstrates a feasibility of using at least 3 generations of repeated RCA for the production of normal structural concrete.

  20. Mechanical Characteristic of Pervious Concrete Considering the Gradation and Size of Coarse Aggregates

    OpenAIRE

    Alireza Joshaghani; Ali Akbar Ramezanianpour; Mohammad Jaberizadeh

    2014-01-01

    Pervious concrete is a kind of sustainable pavement with high permeability which is becoming more common as a storm water management. The purpose of this study was to investigate the effects of coarse aggregate on physical and mechanical properties of the pervious concrete such as density, strength, porosity and permeability at 7, 28, 56 days. This experimental investigation conducted by comparing nine different mixtures. Taguchi design of experiments used to optimize the performance of these...

  1. Exploratory Study of Rubber Seed Shell as Partial Coarse Aggregate Replacement in Concrete

    Directory of Open Access Journals (Sweden)

    K. Muthusamy

    2014-02-01

    Full Text Available Malaysia being a major rubber trees growing country has been generating a large amount of rubber seed shell which regarded as waste. At the same time, the growing construction industry which boosts the concrete production trade has results in higher consumption of natural coarse aggregate which open the door for depletion of this material in future. This study focuses on investigating the possibility of integrating crushed rubber seed shell as partial coarse aggregate replacement material in concrete making. Total of five mixes consisting various content of crushed rubber seed shell as partial coarse aggregate replacement ranging from 0, 5, 10, 15 and 20%, respectively were prepared in form of cubes. All the specimens were water cured before tested at 7 and 28 days. The workability test, compressive strength test and flexural strength test of the mixes was conducted in accordance to MS26 Part 1: Section 2, BSEN 12390 and ASTM 293-79 respectively. Generally, workability, compressive strength and flexural strength decrease with the increase in the crushed rubber seed shell replacement level. However, mix consisting around 10% of crushed rubber seed shell is suitable for the application in concrete work.

  2. Effects of oil palm shell coarse aggregate species on high strength lightweight concrete.

    Science.gov (United States)

    Yew, Ming Kun; Bin Mahmud, Hilmi; Ang, Bee Chin; Yew, Ming Chian

    2014-01-01

    The objective of this study was to investigate the effects of different species of oil palm shell (OPS) coarse aggregates on the properties of high strength lightweight concrete (HSLWC). Original and crushed OPS coarse aggregates of different species and age categories were investigated in this study. The research focused on two OPS species (dura and tenera), in which the coarse aggregates were taken from oil palm trees of the following age categories (3-5, 6-9, and 10-15 years old). The results showed that the workability and dry density of the oil palm shell concrete (OPSC) increase with an increase in age category of OPS species. The compressive strength of specimen CD3 increases significantly compared to specimen CT3 by 21.8%. The maximum achievable 28-day and 90-day compressive strength is 54 and 56 MPa, respectively, which is within the range for 10-15-year-old crushed dura OPS. The water absorption was determined to be within the range for good concrete for the different species of OPSC. In addition, the ultrasonic pulse velocity (UPV) results showed that the OPS HSLWC attain good condition at the age of 3 days. PMID:24982946

  3. Effects of Oil Palm Shell Coarse Aggregate Species on High Strength Lightweight Concrete

    Directory of Open Access Journals (Sweden)

    Ming Kun Yew

    2014-01-01

    Full Text Available The objective of this study was to investigate the effects of different species of oil palm shell (OPS coarse aggregates on the properties of high strength lightweight concrete (HSLWC. Original and crushed OPS coarse aggregates of different species and age categories were investigated in this study. The research focused on two OPS species (dura and tenera, in which the coarse aggregates were taken from oil palm trees of the following age categories (3–5, 6–9, and 10–15 years old. The results showed that the workability and dry density of the oil palm shell concrete (OPSC increase with an increase in age category of OPS species. The compressive strength of specimen CD3 increases significantly compared to specimen CT3 by 21.8%. The maximum achievable 28-day and 90-day compressive strength is 54 and 56 MPa, respectively, which is within the range for 10–15-year-old crushed dura OPS. The water absorption was determined to be within the range for good concrete for the different species of OPSC. In addition, the ultrasonic pulse velocity (UPV results showed that the OPS HSLWC attain good condition at the age of 3 days.

  4. Analysis of moisture state of recycled coarse aggregate and its influence on compression strength of the concrete

    OpenAIRE

    Pelufo Carbonell, María José; Domingo Cabo, Alberto; Ulloa Mayorga, Vivián Andrea; VERGARA ACUÑA, NEEDY NAYIV

    2009-01-01

    p. 2932-2940 This article analyzes the impact of the moisture level of recycled coarse aggregate additions to concrete on its compression strength, with the goal of finding a logical development process that can be reproduced at an industrial level and provide acceptable results for concrete production. This study takes into account the reality in the process of the production of concrete; while many authors suggest the use of recycled coarse aggregates in a saturated state to ensure the d...

  5. Effects of coarse aggregate on compressive strength of dam concrete. Damu concrete no asshuku kyodo ni oyobosu sokotsuzai no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Umehara, H.; Ueda, M. (Nagoya Inst. of Technology, Nagoya (Japan). Faculty of Engineering); Zhang, J. (Yahagi Construction Ltd., Nagoya (Japan)); Yoshida, H. (Nagoya Inst. of Technology, Nagoya (Japan))

    1992-08-20

    Compressive strength of coarse aggregate as well as the bond between coarse aggregate and cement paste effect the compressive strength of concrete greatly. Furthermore the said bond is affected by the bleeding. Consequently, to grasp the level of the voids, under the bottom of the coarse aggregate, caused by the bleeding is the most important in estimating the compressive strength of concrete. However, the researches by now are almost performed on the specimens with Gmax (maximum size of coarse aggregate) being less than 40 mm, and there is nearly none being carried out on a specimen such as dam concrete comprising Gmax as around 150 mm. Now, in the present study, the mechanism of the deterioration of compressive strength in dam concrete due to the voids under the bottom of coarse aggregate is clarified based on the experiment carried out on the alterations of the size, shape, number. location and surface states of the model coarse aggregate in the prepared model concrete made by mortar with Gmax as more than 80 mm. 16 refs., 9 figs., 5 tabs.

  6. 粗集料对粉煤灰混凝土性能影响%Influence of coarse aggregate on properties of fly ash concrete

    Institute of Scientific and Technical Information of China (English)

    汪振双; 王立久

    2011-01-01

    混凝土的架构理论认为混凝土是由砂浆、粗集料和二者之间的界面构成的.试验研究了石灰石、玄武岩、花岗岩和辉绿岩4种不同类型的粗集料对不同粉煤灰掺量混凝土的坍落度、抗压强度、抗折强度和弹性模量的影响,分析了石灰石粗集料对不同粉煤灰掺量混凝土抗冻性的影响.结果表明,粗集料对混凝土的坍落度、抗压强度、抗折强度和弹性模量影响十分显著.粗集料的掺入降低了砂浆基体的扩展度和抗折强度,提高了砂浆基体的抗压强度和弹性模量,此外,粗集料改善了混凝土的抗冻性.随着粉煤灰掺量的增加,混凝土的坍落度提高,但混凝土的力学性能和抗冻性减弱.不同类型的粗集料对混凝土性能的影响相差不大,随着粉煤灰掺量的提高,不同类型粗集料混凝土性能相差也不大.%Concrete is composed of mortar matrix, coarse aggregate and their interface zone according to concrete framework theory. Four different types of coarse aggregate (lime stone, basalt, granite, and diabase) with different volume fraction of fly ash are used to check slump, compressive strength flexural strength and modulus of elasticity, and analyze the influence on frost resistance property o f different fly ash volume fraction for lime stone coarse aggregate. The analytical results show that, slump, compressive strength, flexural strength and modulus of elasticity of concrete are affected by coarse aggregate significantly. Flow ability and flexural strength of concrete are decreased, but compressive strength and modulus of elasticity of concrete are increased due to coarse aggregate mixed, furthermore, coarse aggregate improves frost resistance of concrete. Slump is increased, and mechanical properties and frost resistance property of concrete are decreased with fly ash volume fraction increasing. There is little difference for concrete properties using

  7. Use of Steel Slag as Coarse Aggregate for the Production of Pervious Concrete

    Directory of Open Access Journals (Sweden)

    Georgia Vardaka

    2014-03-01

    Full Text Available Pervious concrete is a type of concrete with significantly increased water permeability, ensuring increased rates of drainage of rainfall. The high porosity is achieved by removing a large percentage of fine aggregates from the mix. The present paper is an approach for the addition of steel slag as a substitute for coarse aggregates in pervious concrete. More specifically, three types of aggregates have been used: steel slag, construction and demolition wastes and conventional limestone aggregates. The produced pervious concretes are compared for their properties, such as water permeability, compressive strength and abrasion behaviour. Also this paper contains the study of the porosity analysis of these pervious concrete mix designs by using porosity profiles produced from X-ray CT Scanning. According to the results of this paper, it is observed that the incorporation of industry by-products or of Construction and Demolition (C&D wastes leads to better abrasion behaviour, and to the increase, in some cases, of the compressive strength and of the water permeability.

  8. Use of Recycling Building Demolition waste As Coarse Aggregate in Hot Mix Asphalt

    Directory of Open Access Journals (Sweden)

    Nabil I. Al- Sarrag* Hanaa Khaleel A Suham E. Saleh Al-Maliky

    2014-04-01

    Full Text Available At the recent years in Iraq, building demolition increase because of wars and the processes of destruction that lead to increase concrete waste, causing extreme pressure on the available land-filled sites that’s becomes a new challenge to local environment, in addition to south region from country poor from aggregate source.  So this study make as first evaluation to return use concrete aggregate for old and demolition building in concrete asphalt mix, the concrete aggregate obtained from building to live long more than 20 years after crash reinforcement concrete and sieving to get requirement granular particle to make locally asphalt mixture (Type IIIB depends on modified specification of State Commission of Roads and Bridges (2003 with percent (0,25,50,75,100% from weight of coarse aggregate.  Asphalt mixtures were tested by Marshall test, Indirect tensile strength test, and the loss of stability test.

  9. Leaching assessment of concrete made of recycled coarse aggregate: physical and environmental characterisation of aggregates and hardened concrete.

    Science.gov (United States)

    Galvín, A P; Agrela, F; Ayuso, J; Beltrán, M G; Barbudo, A

    2014-09-01

    Each year, millions of tonnes of waste are generated worldwide, partially through the construction and demolition of buildings. Recycling the resulting waste could reduce the amount of materials that need to be manufactured. Accordingly, the present work has analysed the potential reuse of construction waste in concrete manufacturing by replacing the natural aggregate with recycled concrete coarse aggregate. However, incorporating alternative materials in concrete manufacturing may increase the pollutant potential of the product, presenting an environmental risk via ground water contamination. The present work has tested two types of concrete batches that were manufactured with different replacement percentages. The experimental procedure analyses not only the effect of the portion of recycled aggregate on the physical properties of concrete but also on the leaching behaviour as indicative of the contamination degree. Thus, parameters such as slump, density, porosity and absorption of hardened concrete, were studied. Leaching behaviour was evaluated based on the availability test performed to three aggregates (raw materials of the concrete batches) and on the diffusion test performed to all concrete. From an environmental point of view, the question of whether the cumulative amount of heavy metals that are released by diffusion reaches the availability threshold was answered. The analysis of concentration levels allowed the establishment of different groups of metals according to the observed behaviour, the analysis of the role of pH and the identification of the main release mechanisms. Finally, through a statistical analysis, physical parameters and diffusion data were interrelated. It allowed estimating the relevance of porosity, density and absorption of hardened concrete on diffusion release of the metals in study. PMID:24889792

  10. Leaching assessment of concrete made of recycled coarse aggregate: physical and environmental characterisation of aggregates and hardened concrete.

    Science.gov (United States)

    Galvín, A P; Agrela, F; Ayuso, J; Beltrán, M G; Barbudo, A

    2014-09-01

    Each year, millions of tonnes of waste are generated worldwide, partially through the construction and demolition of buildings. Recycling the resulting waste could reduce the amount of materials that need to be manufactured. Accordingly, the present work has analysed the potential reuse of construction waste in concrete manufacturing by replacing the natural aggregate with recycled concrete coarse aggregate. However, incorporating alternative materials in concrete manufacturing may increase the pollutant potential of the product, presenting an environmental risk via ground water contamination. The present work has tested two types of concrete batches that were manufactured with different replacement percentages. The experimental procedure analyses not only the effect of the portion of recycled aggregate on the physical properties of concrete but also on the leaching behaviour as indicative of the contamination degree. Thus, parameters such as slump, density, porosity and absorption of hardened concrete, were studied. Leaching behaviour was evaluated based on the availability test performed to three aggregates (raw materials of the concrete batches) and on the diffusion test performed to all concrete. From an environmental point of view, the question of whether the cumulative amount of heavy metals that are released by diffusion reaches the availability threshold was answered. The analysis of concentration levels allowed the establishment of different groups of metals according to the observed behaviour, the analysis of the role of pH and the identification of the main release mechanisms. Finally, through a statistical analysis, physical parameters and diffusion data were interrelated. It allowed estimating the relevance of porosity, density and absorption of hardened concrete on diffusion release of the metals in study.

  11. An eco-friendly self-compacting concrete with recycled coarse aggregates

    Directory of Open Access Journals (Sweden)

    Pereira-de Oliveira, L. A.

    2013-09-01

    Full Text Available The potential uses of coarse recycled aggregates in the composition of SCC increases the ecological value and partly solve the issues of waste disposal sites generated by construction and demolition of structures. Thus, this paper present an experimental study of SCC properties where the normal coarse aggregates were replaced by different percentages of recycled aggregates, i.e., 0% (SCC, 10% (SCCR10, 20% (SCCR20, 30% (SCCR30 and 40% (SCCR40. The results from fresh concrete (rheological properties and self-compactability as the hardened concrete properties (compressive strength, density and dynamic modulus of elasticity, show only minor discrepancies. From the standpoint of mechanical behaviour, the results confirm the viability to incorporate coarse recycled aggregates in the SCC demonstrating the conservative character of the currently recommended limits.Los usos potenciales de áridos gruesos reciclados en la composición del hormigón autocompactante (SCC aumenta el valor ecológico y en parte resuelve los problemas de los sitios de disposición de residuos generados por la construcción y la demolición de las estructuras. Por lo tanto, este trabajo presenta un estudio experimental de las propiedades de SCC en el cual los áridos gruesos naturales fueron reemplazados por distintos porcentajes de áridos reciclados, es decir, 0% (SCC, el 10% (SCCR10, el 20% (SCCR20, el 30% (SCCR30 y el 40% (SCCR40. Los resultados del hormigón fresco (propiedades reológicas y la auto-compactación, como las propiedades de hormigón endurecido (resistencia a la compresión, densidad y módulo de elasticidad dinámico, muestran sólo pequeñas discrepancias. Desde el punto de vista del comportamiento mecánico, los resultados confirman la viabilidad de incorporar áridos gruesos reciclados en los SCC demostrando el carácter conservador de los límites actualmente recomendados.

  12. STUDIES ON STRENGTH CHARACTERISTICS ON UTILIZATION OF WASTE MATERIALS AS COARSE AGGREGATE IN CONCRETE

    Directory of Open Access Journals (Sweden)

    DR. T. SEKAR

    2011-07-01

    Full Text Available Depletion of natural resources is a common phenomenon in developing countries like India due to rapid urbanization and Industrialization involving construction of Infrastructure and other amenities. In view of this, people have started searching for suitable other viable alternative materials for concrete so that the existing natural resources could be preserved to the possible extent, for the future generation. In this process, different industrial waste materials such as fly ash, blast furnace slag, quarry dust, tile waste, brick bats, broken glass waste, waste aggregate from demolition of structures, ceramic insulator waste, etc. have been tried as a viablesubstitute material to the conventional materials in concrete and has also been succeeded. This paper describes the studies conducted on strength characteristics of concrete made with utilizing waste materials viz: ceramic tiles, ceramic insulator waste, and broken glass pieces. A total number of 24cubes, 24 cylinders and 24 beamswere cast and tested for compressive strength, splitting tensile strength and flexural strength using industrial wastes and the results presented. It was found that, the concrete made of waste ceramic tile aggregate produced more strength in compression, split tensile and flexure than ceramic insulator scrap and broken glass material. This paper recommends that waste ceramic tiles can be used as an alternate construction material to coarse aggregate in concrete.

  13. Application of Coconut Shell as Coarse Aggregate in Concrete: A Technical Review

    Directory of Open Access Journals (Sweden)

    Parag S. Kambli

    2014-03-01

    Full Text Available Oil palm shell (OPS is a waste from the agricultural sector and is available in large quantities in the tropical regions. The high cost of conventional building materials is a major factor affecting housing delivery in world. This has necessitated research into alternative materials of construction. The project paper aims at analysing compressive strength characteristics of concrete produced using crushed, granular coconut as substitutes for conventional coarse aggregate with partial replacement. The main objective is to encourage the use of these ‘seemingly’ waste products as construction materials in low-cost housing. It is also expected to serve the purpose of encouraging housing developers in investing these materials in house construction.

  14. Investigating bile salt aggregation using coarse-grained molecular dynamics simulations

    Science.gov (United States)

    Vila Verde, Ana; Frenkel, Daan

    2010-03-01

    Bile salts are necessary for fat digestion due to their unusual surfactant properties: they assemble into small, polydisperse micelles and easily form mixed micelles with poorly soluble amphiphiles. Understanding these properties requires molecular scale information about bile salt micelles, something challenging to obtain experimentally but amenable to computational modeling. To address this issue we build a coarse-grained model of bile salts. We investigate their aggregation behavior through molecular dynamics simulations in a grand-canonical parallel tempering scheme. We validate our model against available solubility and light scattering data. Our results indicate that at physiological bile salt and counter ion concentrations, bile salts pack in many different orientations in pure bile micelles, contrary to standard surfactants. This feature may be physiologically relevant, allowing bile salts to solubilize the heterogeneous blends of fats typical of digestion.

  15. Durability and Shrinkage Characteristics of Self-Compacting Concretes Containing Recycled Coarse and/or Fine Aggregates

    Directory of Open Access Journals (Sweden)

    Mehmet Gesoglu

    2015-01-01

    Full Text Available This paper addresses durability and shrinkage performance of the self-compacting concretes (SCCs in which natural coarse aggregate (NCA and/or natural fine aggregate (NFA were replaced by recycled coarse aggregate (RCA and/or recycled fine aggregate (RFA, respectively. A total of 16 SCCs were produced and classified into four series, each of which included four mixes designed with two water to binder (w/b ratios of 0.3 and 0.43 and two silica fume replacement levels of 0 and 10%. Durability properties of SCCs were tested for rapid chloride penetration, water sorptivity, gas permeability, and water permeability at 56 days. Also, drying shrinkage accompanied by the water loss and restrained shrinkage of SCCs were monitored over 56 days of drying period. Test results revealed that incorporating recycled coarse and/or fine aggregates aggravated the durability properties of SCCs tested in this study. The drying shrinkage and restrained shrinkage cracking of recycled aggregate (RA concretes had significantly poorer performance than natural aggregate (NA concretes. The time of cracking greatly prolonged as the RAs were used along with the increase in water/binder ratio.

  16. Properties of Concrete on Replacement of Coarse Aggregate and Cementitious Materials with Styfoam And Rice Husk Ash Respectively

    Directory of Open Access Journals (Sweden)

    Ananya Sheth

    2016-07-01

    Full Text Available This paper reports an experimental investigation on the influence of Rice Husk Ash (RHAand Expanded Poly Styrene (EPS on the mechanical properties and the properties of fresh concrete of the produced RHA and EPS blended concrete. EPS aggregates were used to replace coarse aggregates by volume with an aim to decrease the unit weight. Locally produced RHA was used to replace cement by its weight with an aim to increase workability. Mixture proportioning was performed to produce target strength of 65 MPa. Past researches regarding complete replacement of coarse aggregates with EPS aggregates have shown strength of less than 10 MPa. Hence, our aim is to achieve strength of 25-30 MPa thereby utilizing environmentally sustainable concrete in the rapidly developing low cost housing sectors of developing countries.

  17. A comparative study of concrete properties using coconut shell and palm kernel shell as coarse aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Olanipekun, E.A.; Olusola, K.O.; Ata, O. [Obafemi Awolowo University, Ile-Ife, Osun State (Nigeria). Department of Building

    2006-03-15

    The high cost of conventional building materials is a major factor affecting housing delivery in Nigeria. This has necessitated research into alternative materials of construction. This paper presents the results of an investigation carried out on the comparative cost analysis and strength characteristics of concrete produced using crushed, granular coconut and palm kernel shells as substitutes for conventional coarse aggregate in gradation of 0%, 25%, 50%, 75% and 100%. Two mix ratios (1:1:2 and 1:2:4) were used. A total of 320 cubes of size 100x100x100mm were cast, tested and their physical and mechanical properties determined. The results of the tests showed that the compressive strength of the concrete decreased as the percentage of the shells increased in the two mix ratios. However, concrete obtained from coconut shells exhibited a higher compressive strength than palm kernel shell concrete in the two mix proportions. The results also indicated cost reduction of 30% and 42% for concrete produced from coconut shells and palm kernel shells, respectively. Considering the strength/economy ratio, it was concluded that coconut shells were more suitable than palm kernel shells when used as substitute for conventional aggregates in concrete production. (author)

  18. Effect of different sizes of coarse aggregate on the properties of NCC and SCC

    Directory of Open Access Journals (Sweden)

    A.V.Krishna,

    2010-10-01

    Full Text Available Self-Compacting concrete (SCC needs no external vibration and compacts fully under its self weight. This paper describes experimental work carried out to develop SCC and to study the effect of different sizes (i.e., 20mm; 16mm; 12.5mm and 10mm of coarse aggregate (C.A on the properties of SCC. Eight mixes were investigated for M30 grade concrete. The water-powder ratio was kept fixed throughout the SCC mixes. The superplasticizer (S.P(Structuro 100 and viscosity modifying admixture (V.M.A(Structo 480 dosages was determined from mortar trails. To achieve self-compacting properties, successive replacement of C.A by fine aggregate was adapted. Slump flow test, V-funnel test, J-ring test and L-box test on fresh concrete were carried out as per EFNARC guidelines. The compressive strength, split tensile strength and flexural strength of the concrete after 7, 28 &56 days curing were also investigated. The test results showed how Self-Compacting properties were achieved as different sizes of C.A.

  19. FRP-Confined Recycled Coarse Aggregate Concrete: Experimental Investigation and Model Comparison

    Directory of Open Access Journals (Sweden)

    Yingwu Zhou

    2016-10-01

    Full Text Available The in situ application of recycled aggregate concrete (RAC is of great significance in environmental protection and construction resources sustainability. However, it has been limited to nonstructural purposes due to its poor mechanical performance. External confinement using steel tubes and fiber-reinforced polymer (FRP can significantly improve the mechanical performance of RAC and thus the first-ever study on the axial compressive behavior of glass FRP (GFRP-confined RAC was recently reported. To have a full understanding of FRP-confined RAC, this paper has extended the type of FRP and presents a systematic experimental study on the axial compressive performance of carbon FRP (CFRP-confined RAC. The mechanical properties of CFRP-confined RAC from the perspective of the failure mode, ultimate strength and strain, and stress–strain relationship responses were analyzed. Integrated with existing experimental data of FRP-confined RAC, the paper compiles a database for the mechanical properties of FRP-confined RAC. Based on the database, the effects of FRP type (i.e., GFRP and CFRP and the replacement ratio of recycled coarse aggregate were investigated. The results indicated that the stress–stain behavior of FRP-confined RAC depended heavily on the unconfined concrete strength and the FRP confining pressure instead of the replacement ratio. Therefore, this study adopted eleven high-performance ultimate strength and strain models developed for FRP-confined normal aggregate concrete (NAC to predict the mechanical properties of FRP-confined RAC. All the predictions had good agreement with the test results, which further confirmed similar roles played by FRP confinement in improving the mechanical properties of RAC and improving those of NAC. On this basis, this paper finally recommended a stress–strain relationship model for FRP-confined RAC.

  20. CAMELOT: A machine learning approach for coarse-grained simulations of aggregation of block-copolymeric protein sequences

    Energy Technology Data Exchange (ETDEWEB)

    Ruff, Kiersten M. [Computational and Systems Biology Program and Center for Biological Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63130-4899 (United States); Harmon, Tyler S. [Department of Physics and Center for Biological Systems Engineering, Washington University in St. Louis, St. Louis, Missouri 63130-4899 (United States); Pappu, Rohit V., E-mail: pappu@wustl.edu [Department of Biomedical Engineering and Center for Biological Systems Engineering, Washington University in St. Louis, CB 1097, St. Louis, Missouri 63130-4899 (United States)

    2015-12-28

    We report the development and deployment of a coarse-graining method that is well suited for computer simulations of aggregation and phase separation of protein sequences with block-copolymeric architectures. Our algorithm, named CAMELOT for Coarse-grained simulations Aided by MachinE Learning Optimization and Training, leverages information from converged all atom simulations that is used to determine a suitable resolution and parameterize the coarse-grained model. To parameterize a system-specific coarse-grained model, we use a combination of Boltzmann inversion, non-linear regression, and a Gaussian process Bayesian optimization approach. The accuracy of the coarse-grained model is demonstrated through direct comparisons to results from all atom simulations. We demonstrate the utility of our coarse-graining approach using the block-copolymeric sequence from the exon 1 encoded sequence of the huntingtin protein. This sequence comprises of 17 residues from the N-terminal end of huntingtin (N17) followed by a polyglutamine (polyQ) tract. Simulations based on the CAMELOT approach are used to show that the adsorption and unfolding of the wild type N17 and its sequence variants on the surface of polyQ tracts engender a patchy colloid like architecture that promotes the formation of linear aggregates. These results provide a plausible explanation for experimental observations, which show that N17 accelerates the formation of linear aggregates in block-copolymeric N17-polyQ sequences. The CAMELOT approach is versatile and is generalizable for simulating the aggregation and phase behavior of a range of block-copolymeric protein sequences.

  1. CAMELOT: A machine learning approach for coarse-grained simulations of aggregation of block-copolymeric protein sequences

    Science.gov (United States)

    Ruff, Kiersten M.; Harmon, Tyler S.; Pappu, Rohit V.

    2015-12-01

    We report the development and deployment of a coarse-graining method that is well suited for computer simulations of aggregation and phase separation of protein sequences with block-copolymeric architectures. Our algorithm, named CAMELOT for Coarse-grained simulations Aided by MachinE Learning Optimization and Training, leverages information from converged all atom simulations that is used to determine a suitable resolution and parameterize the coarse-grained model. To parameterize a system-specific coarse-grained model, we use a combination of Boltzmann inversion, non-linear regression, and a Gaussian process Bayesian optimization approach. The accuracy of the coarse-grained model is demonstrated through direct comparisons to results from all atom simulations. We demonstrate the utility of our coarse-graining approach using the block-copolymeric sequence from the exon 1 encoded sequence of the huntingtin protein. This sequence comprises of 17 residues from the N-terminal end of huntingtin (N17) followed by a polyglutamine (polyQ) tract. Simulations based on the CAMELOT approach are used to show that the adsorption and unfolding of the wild type N17 and its sequence variants on the surface of polyQ tracts engender a patchy colloid like architecture that promotes the formation of linear aggregates. These results provide a plausible explanation for experimental observations, which show that N17 accelerates the formation of linear aggregates in block-copolymeric N17-polyQ sequences. The CAMELOT approach is versatile and is generalizable for simulating the aggregation and phase behavior of a range of block-copolymeric protein sequences.

  2. CAMELOT: A machine learning approach for coarse-grained simulations of aggregation of block-copolymeric protein sequences

    International Nuclear Information System (INIS)

    We report the development and deployment of a coarse-graining method that is well suited for computer simulations of aggregation and phase separation of protein sequences with block-copolymeric architectures. Our algorithm, named CAMELOT for Coarse-grained simulations Aided by MachinE Learning Optimization and Training, leverages information from converged all atom simulations that is used to determine a suitable resolution and parameterize the coarse-grained model. To parameterize a system-specific coarse-grained model, we use a combination of Boltzmann inversion, non-linear regression, and a Gaussian process Bayesian optimization approach. The accuracy of the coarse-grained model is demonstrated through direct comparisons to results from all atom simulations. We demonstrate the utility of our coarse-graining approach using the block-copolymeric sequence from the exon 1 encoded sequence of the huntingtin protein. This sequence comprises of 17 residues from the N-terminal end of huntingtin (N17) followed by a polyglutamine (polyQ) tract. Simulations based on the CAMELOT approach are used to show that the adsorption and unfolding of the wild type N17 and its sequence variants on the surface of polyQ tracts engender a patchy colloid like architecture that promotes the formation of linear aggregates. These results provide a plausible explanation for experimental observations, which show that N17 accelerates the formation of linear aggregates in block-copolymeric N17-polyQ sequences. The CAMELOT approach is versatile and is generalizable for simulating the aggregation and phase behavior of a range of block-copolymeric protein sequences

  3. The influence of coarse aggregate size and volume on the fracture behavior and brittleness of self-compacting concrete

    International Nuclear Information System (INIS)

    This paper presents the results of an experimental investigation on fracture characteristics and brittleness of self-compacting concrete (SCC), involving the tests of 185 three point bending beams with different coarse aggregate size and content. Generally, the parameters were analyzed by the work of fracture method (WFM) and the size effect method (SEM). The results showed that with increase of size and content of coarse aggregate, (a) the fracture energy increases which is due to the change in fractal dimensions, (b) behavior of SCC beams approaches strength criterion, (c) characteristic length, which is deemed as an index of brittleness, increases linearly. It was found with decrease of w/c ratio that fracture energy increases which may be explained by the improvement in structure of aggregate-paste transition zone. Also, the results showed that there is a correlation between the fracture energy measured by WFM (GF) and the value measured through SEM (Gf) (GF = 3.11Gf)

  4. The prediction of the freeze/thaw durability of coarse aggregate in concrete by mercury intrusion porosimetry

    Science.gov (United States)

    Lindgren, M. N.

    1980-10-01

    Aggregates from fifty-two Indiana highway cores were tested as were five rock samples supplied by the Portland Cement Association. The Expected Durability Factor values were determined from the pore size distributions, and an average value was assigned to each pavement associated with the cores. These values were then compared with the field performance of the pavement to ascertain the borderline between EDF values for durable and for nondurable aggregates. A good correlation between the field performance and the average EDF values was found. A pavement will be durable if its coarse aggregate has an EDF value greater than 50 for 90% or more of the aggregate. This criterion applies to stone and gravel aggregates with a maximum size of 1-1/2 to 2-1/2 inches. The pavement will be durable for at lest thirty years.

  5. Effect of Coarse Aggregate Sizes and Replacement Levels on the Strength of Palm Kernel Shell (PKS Concrete

    Directory of Open Access Journals (Sweden)

    Olusola, K.O.

    2013-01-01

    Full Text Available The maximum coarse aggregate size used in concrete can impact on its strength. An investigation of the effect of coarse aggregate size and replacement level of granite with palm kernel shell (PKS on the compressive and tensile strengths of PKS concrete were investigated. Mix proportion by weight of 1:1½:2 with w/c of 0.50 were used. All samples were tested at 7 and up to 90 days. Results showed that both compressive and splitting tensile strengths increased with increase in aggregate sizes. Both strengths however decreased with increase in replacement levels of granite with PKS. Optimum replacement level of granite with PKS was 25% with compressive and tensile strengths of 22.97 N/mm2 and 1.89 N/mm2 respectively at maximum coarse aggregate size of 20 mm. However, at 50% PKS content, which results in lightweight concrete, compressive strength was 18.13 N/mm2 which is above the minimum value of 17 MPa for lightweight concrete.

  6. Experimental Study on Performance of Concrete M30 with Partial Replacement of Coarse Aggregate with Sea Shells and Coconut Shells

    Directory of Open Access Journals (Sweden)

    Gurikini Lalitha

    2014-08-01

    Full Text Available In this research work experiments have been conducted with collection of materials required and the data required for mix design are obtained by sieve analysis and specific gravity test. Sieve analysis is carried out from various fine aggregates (FA and coarse aggregates (CA samples and the sample which suits the requirement is selected. Specific gravity tests are carried out for fine and coarse aggregate. The various materials used were tested as per Indian standard specifications. On the basis of the experimental studies carried out on M30 grade concrete as partial replacement of coarse aggregates with sea shells and coconut shells, the following conclusions are drawn from the above experiment we conclude that comparing to traditional concrete, compressive strength of 10% (5% + 5% of coconut shells (5% and sea shells (5% increased. whereas the compressive strength of the concrete cubes has gradually decreased from addition of 10% (5% + 5% of coconut shells and sea shells. Hence for economical view 10% is preferable and in the perspective of compressive strength 10% is suggested. Thus, 10% replacement coconut shells and sea shells are recommended for both heavy weight and light weight concrete production.

  7. Chloride corrosion of embedded reinforced steel on concrete elaborated from recycled coarse aggregates and supplementary cement materials

    OpenAIRE

    Corral Higuera, Ramón; Arredondo Rea, Susana Paola; Almaral Sánchez, Jorge Luis; Gómez Soberón, José Manuel Vicente

    2013-01-01

    As a result of contributive and sustainable strategies on concrete industry, researches are presently being developed, which are focused on improving durability of reinforced concrete structures as well as partially or completely replacing their components by recycled materials. In the case of steel bars, corrosion is considered as the major durability menace to reinforced concrete. The present research employed coarse aggregate from recycled concrete and supplementary cement materials,...

  8. Fundamental Study on the Development of Structural Lightweight Concrete by Using Normal Coarse Aggregate and Foaming Agent

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2014-06-01

    Full Text Available Structural lightweight concrete (SLWC has superior properties that allow the optimization of super tall structure systems for the process of design. Because of the limited supply of lightweight aggregates in Korea, the development of structural lightweight concrete without lightweight aggregates is needed. The physical and mechanical properties of specimens that were cast using normal coarse aggregates and different mixing ratios of foaming agent to evaluate the possibility of creating structural lightweight concrete were investigated. The results show that the density of SLWC decreases as the dosage of foaming agent increases up to a dosage of 0.6%, as observed by SEM. It was also observed that the foaming agent induced well separated pores, and that the size of the pores ranged from 50 to 100 μm. Based on the porosity of concrete specimens with foaming agent, compressive strength values of structural lightweight foam concrete (SLWFC were obtained. It was also found that the estimated values from proposed equations for compressive strength and modulus of elasticity of SLWFC, and values obtained by actual measurements were in good agreement. Thus, this study confirms that new structural lightweight concrete using normal coarse aggregates and foaming agent can be developed successfully.

  9. The Effect of Morphological Characteristic of Coarse Aggregates Measured with Fractal Dimension on Asphalt Mixture’s High-Temperature Performance

    Directory of Open Access Journals (Sweden)

    Hainian Wang

    2016-01-01

    Full Text Available The morphological properties of coarse aggregates, such as shape, angularity, and surface texture, have a great influence on the mechanical performance of asphalt mixtures. This study aims to investigate the effect of coarse aggregate morphological properties on the high-temperature performance of asphalt mixtures. A modified Los Angeles (LA abrasion test was employed to produce aggregates with various morphological properties by applying abrasion cycles of 0, 200, 400, 600, 800, 1000, and 1200 on crushed angular aggregates. Based on a laboratory-developed Morphology Analysis System for Coarse Aggregates (MASCA, the morphological properties of the coarse aggregate particles were quantified using the index of fractal dimension. The high-temperature performances of the dense-graded asphalt mixture (AC-16, gap-graded stone asphalt mixture (SAC-16, and stone mastic asphalt (SMA-16 mixtures containing aggregates with different fractal dimensions were evaluated through the dynamic stability (DS test and the penetration shear test in laboratory. Good linear correlations between the fractal dimension and high-temperature indexes were obtained for all three types of mixtures. Moreover, the results also indicated that higher coarse aggregate angularity leads to stronger high-temperature shear resistance of asphalt mixtures.

  10. Sea Dredged Gravel versus Crushed Granite as Coarse Aggregate for Self Compacting Concrete in Aggressive Environment

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.; Kristensen, Lasse Frølich

    2007-01-01

    modulus of elasticity. Tensile and compressive strength were found to depend both on aggregate type and on the properties of the interfacial zone close to the aggregate surface. Freeze-thaw scaling resistance was good with crushed granite, whereas sea gravel led to more severe scaling caused by porphyry...

  11. Mechanisms and Kinetics of Amyloid Aggregation Investigated by a Phenomenological Coarse-Grained Model

    Science.gov (United States)

    Magno, Andrea; Pellarin, Riccardo; Caflisch, Amedeo

    Amyloid fibrils are ordered polypeptide aggregates that have been implicated in several neurodegenerative pathologies, such as Alzheimer's, Parkinson's, Huntington's, and prion diseases, [1, 2] and, more recently, also in biological functionalities. [3, 4, 5] These findings have paved the way for a wide range of experimental and computational studies aimed at understanding the details of the fibril-formation mechanism. Computer simulations using low-resolution models, which employ a simplified representation of protein geometry and energetics, have provided insights into the basic physical principles underlying protein aggregation in general [6, 7, 8] and ordered amyloid aggregation. [9, 10, 11, 12, 13, 14, 15] For example, Dokholyan and coworkers have used the Discrete Molecular Dynamics method [16, 17] to shed light on the mechanisms of protein oligomerization [18] and the conformational changes that take place in proteins before the aggregation onset. [19, 20] One challenging observation, which is difficult to observe by computer simulations, is the wide range of aggregation scenarios emerging from a variety of biophysical measurements. [21, 22] Atomistic models have been employed to study the conformational space of amyloidogenic polypeptides in the monomeric state, [23, 24, 25] the very initial steps of amyloid formation, [26, 27, 28, 29, 30, 31, 32] and the structural stability of fibril models. [33, 34, 35) However, all-atom simulations of the kinetics of fibril formation are beyond what can be done with modern computers.

  12. The Feasibility of Palm Kernel Shell as a Replacement for Coarse Aggregate in Lightweight Concrete

    Science.gov (United States)

    Itam, Zarina; Beddu, Salmia; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Issa Ayash, Usama

    2016-03-01

    Implementing sustainable materials into the construction industry is fast becoming a trend nowadays. Palm Kernel Shell is a by-product of Malaysia’s palm oil industry, generating waste as much as 4 million tons per annum. As a means of producing a sustainable, environmental-friendly, and affordable alternative in the lightweight concrete industry, the exploration of the potential of Palm Kernel Shell to be used as an aggregate replacement was conducted which may give a positive impact to the Malaysian construction industry as well as worldwide concrete usage. This research investigates the feasibility of PKS as an aggregate replacement in lightweight concrete in terms of compressive strength, slump test, water absorption, and density. Results indicate that by using PKS for aggregate replacement, it increases the water absorption but decreases the concrete workability and strength. Results however, fall into the range acceptable for lightweight aggregates, hence it can be concluded that there is potential to use PKS as aggregate replacement for lightweight concrete.

  13. Applicability assessment of concrete with recycled coarse aggregates in Havana, Cuba

    Directory of Open Access Journals (Sweden)

    Pavón, E.

    2012-09-01

    Full Text Available The recent viability studies carried out in Havana, Cuba, according to natural or recycled aggregates, exhibited high volume production of construction and demolition waste (CDW. The last well-known data of concrete waste generation reached to 1800 m3/month. This situation, together with the depletion of the quarry aggregates closed to the capital, requires the use of such debris as aggregate for concrete production. In this work, four origin recycled concrete aggregates (RCA were produced and characterized. Recycled aggregate concrete with 25%, 50% and 100% of RCA and 0.45, 0.50 and 0.55 of water-cement ratio were produced. Physical, mechanical and durabilidty properties of thoses concretes were determined and evaluated, and their applicability as structural material in different aggressive environments according to Cuban normative was defined.Los estudios de viabilidad realizados recientemente en La Habana, Cuba muestran elevadas cifras de producción de residuos de construcción y demolición (RCD. Los últimos datos conocidos de generación de escombros de hormigón alcanzan valores cercanos a los 1800m3/mensual. Esta situación unida al agotamiento de los áridos en las zonas cercanas a la capital hace necesaria la utilización de estos escombros como áridos en la fabricación de hormigones. En el trabajo realizado se trituraron escombros de hormigón de cuatro orígenes diferentes, después de su caracterización se fabricaron hormigones con 25%, 50% y 100% de árido reciclado y con relaciones agua-cemento de 0.45, 0.50 y 0.55. A partir de la evaluación de las propiedades físico-mecánicas y de durabilidad obtenidas por los hormigones reciclados, se define la aplicabilidad de los mismos como hormigón estructural para ser utilizados en los diferentes tipos de ambientes de agresividad que tiene definido la normativa cubana.

  14. Effects of macromolecular crowding on amyloid beta (16-22) aggregation using coarse-grained simulations.

    Science.gov (United States)

    Latshaw, David C; Cheon, Mookyung; Hall, Carol K

    2014-11-26

    To examine the effect of crowding on protein aggregation, discontinuous molecular dynamics (DMD) simulations combined with an intermediate resolution protein model, PRIME20, were applied to a peptide/crowder system. The systems contained 192 Aβ(16-22) peptides and crowders of diameters 5, 20, and 40 Å, represented here by simple hard spheres, at crowder volume fractions of 0.00, 0.10, and 0.20. Results show that both crowder volume fraction and crowder diameter have a large impact on fibril and oligomer formation. The addition of crowders to a system of peptides increases the rate of oligomer formation, shifting from a slow ordered formation of oligomers in the absence of crowders, similar to nucleated polymerization, to a fast collapse of peptides and subsequent rearrangement characteristic of nucleated conformational conversion with a high maximum in the number of peptides in oligomers as the total crowder surface area increases. The rate of conversion from oligomers to fibrils also increases with increasing total crowder surface area, giving rise to an increased rate of fibril growth. In all cases, larger volume fractions and smaller crowders provide the greatest aggregation enhancement effects. We also show that the size of the crowders influences the formation of specific oligomer sizes. In our simulations, the 40 Å crowders enhance the number of dimers relative to the numbers of trimers, hexamers, pentamers, and hexamers, while the 5 Å crowders enhance the number of hexamers relative to the numbers of dimers, trimers, tetramers, and pentamers. These results are in qualitative agreement with previous experimental and theoretical work.

  15. A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate.

    Science.gov (United States)

    Sekaran, Alan; Palaniswamy, Murthi; Balaraju, Sivagnanaprakash

    2015-01-01

    Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i) Mix A, conventional concrete mix with no material substitution, (ii) Mix B, 30% replacement of cement with fly ash, and (iii) Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C) had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications.

  16. A Study on Suitability of EAF Oxidizing Slag in Concrete: An Eco-Friendly and Sustainable Replacement for Natural Coarse Aggregate

    Directory of Open Access Journals (Sweden)

    Alan Sekaran

    2015-01-01

    Full Text Available Environmental and economic factors increasingly encourage higher utility of industrial by-products. The basic objective of this study was to identify alternative source for good quality aggregates which is depleting very fast due to fast pace of construction activities in India. EAF oxidizing slag as a by-product obtained during the process in steel making industry provides great opportunity to utilize it as an alternative to normally available coarse aggregates. The primary aim of this research was to evaluate the physical, mechanical, and durability properties of concrete made with EAF oxidizing slag in addition to supplementary cementing material fly ash. This study presents the experimental investigations carried out on concrete grades of M20 and M30 with three mixes: (i Mix A, conventional concrete mix with no material substitution, (ii Mix B, 30% replacement of cement with fly ash, and (iii Mix C, 30% replacement of cement with fly ash and 50% replacement of coarse aggregate with EAF oxidizing slag. Tests were conducted to determine mechanical and durability properties up to the age of 90 days. The test results concluded that concrete made with EAF oxidizing slag and fly ash (Mix C had greater strength and durability characteristics when compared to Mix A and Mix B. Based on the overall observations, it could be recommended that EAF oxidizing slag and fly ash could be effectively utilized as coarse aggregate replacement and cement replacement in all concrete applications.

  17. Cohesive Fracture Study of a Bonded Coarse Silica Sand Aggregate Bond Interface Subjected to Mixed-Mode Bending Conditions

    Directory of Open Access Journals (Sweden)

    Donna Chen

    2013-12-01

    Full Text Available One of the primary objectives in the design of composite structures is the prevention of premature bond failure. Therefore, the characterization of cohesive behavior is an important field of study in structural engineering. Using fracture mechanics principles, the cohesive behavior of an epoxy bonded coarse silica sand aggregate bond interface is studied in this paper, with a focus on finding a general analytical form of idealizing its behavior when used in a specimen possessing asymmetric and inhomogeneous qualities. Two series of small-scale specimens were experimentally tested under mixed-mode bending (MMB conditions, where it was found that there was negligible influence exerted on the fracture energy of the interface due to changes in the mixed-mode ratio or initial crack length. Using finite element analysis (FEA methods, an appropriate bilinear traction-separation model was developed to both validate as well as obtain a set of consistent parameters applicable to all tested specimens. Comparison of the Global Method and the Local Method, used to obtain partitioned Mode I and Mode II fracture energy values from MMB specimens, were made, with the conclusion that both methods are adequate in the calculation of the total fracture energy though the Local Method should be used to obtain accurate partitioned Mode I and Mode II fracture energy values. Idealization of the bond interface using the cohesive parameters derived can be accurately achieved by the use of both contact interactions and cohesive elements in two-dimensional and three-dimensional FE models, though the results obtained using contact interactions would be expected to exhibit greater global stiffness.

  18. 再生粗骨料混凝土早期强度试验研究%Experimental research on early strength of recycled coarse aggregate concrete

    Institute of Scientific and Technical Information of China (English)

    张兴才; 李洪明; 朱磊

    2015-01-01

    The influences of water-cement ratio,replacement ratio of recycled coarse aggregate,and water amount on early compres-sive strength and flexural strength of recycled concrete were investigated by experiments. Research results show that the strength ratio of recycled coarse aggregate concrete didn′t vary with water-cement ratio,replacement ratio and water amount,the compressive strength and flexural strength at different ages decrease with the water-cement ratio and replacement ratio. The models for early compressive strength and flexural strength of recycled concrete with 100% replacement of recycled coarse aggregate are established according to ex-periment results,and the calculated values of the strength of recycled coarse aggregate concrete are in good agreement with the test val-ues obtained by other researchers.%通过试验研究水灰比、再生粗骨料取代率和用水量对再生混凝土早期抗压强度和抗折强度的影响。研究结果表明,再生混凝土各龄期的强度系数随水灰比、骨料取代率、单位用水量等因素变化不大。再生混凝土的各个龄期的抗压和抗折强度均随水灰比和再生骨料取代率的增大而降低。根据试验结果建立了再生粗骨料取代率为100%的再生混凝土早期抗压强度和抗折强度计算模型,该模型计算结果与他人试验结果吻合较好。

  19. Experimental Study on the Frost Resistance of Recycled Coarse Aggregate Concrete%再生粗骨料混凝土抗冻性试验研究

    Institute of Scientific and Technical Information of China (English)

    冯嘉; 李秋义; 宋菁; 张健

    2011-01-01

    再生混凝土的研究与应用对于保护环境具有重大意义,其耐久性则是影响生产应用的重要指标.重点研究了再生粗骨料取代量、矿物掺和料等因素对再生混凝土抗冻性的影响.结果表明:再生粗骨料混凝土的质量损失率均满足5%的试验要求,且质量损失率随着再生骨料取代率的增加而下降;再生粗骨料混凝土的相对动弹模量低于天然骨料混凝土,达到了冻融循环抵抗性指标,满足抗冻性要求;掺普通矿粉的再生混凝土比掺粉煤灰的再生混凝土抗冻性好;硅灰对提高再生混凝土(掺粉煤灰)的抗冻性有明显作用.%The research and application of recycled concrete are of great significance for environmental protection and its durability is an important index of production and application.The influences of the replacement rate of recycled coarse aggregate,mineral admixture and other factors on the frost resistance of recycled concrete are studied in this paper.The experimental results show that the mass loss rate of recycled coarse aggregate concrete meets the experimental requirement by 5% and it descends along with the increase of the replacement rate of the recycled fine aggregate.The relative dynamic modulus of recycled coarse aggregate concrete is inferior to that of the natural aggregate concrete,but it reaches the freeze-thawing circulation norm and meets frost resistance requirements.The frost resistance of the recycled aggregate concrete with mineral powder is better than that of the recycled aggregate concrete with fly ash.The silicon ash can enhance the frost resistance of the recycled concrete(with fly ash) significantly.

  20. 再生粗骨料取代率对混凝土各项性能的影响%Effects of Replacement Ratio of Recycled Coarse Aggregate on Properties of Concrete

    Institute of Scientific and Technical Information of China (English)

    全洪珠; 袁传鹏; 迟玉锦

    2011-01-01

    利用不同品质的3种再生粗骨料,研究了再生粗骨料取代率对混凝土的工作性能、力学性能及干缩性能的影响.结果表明,利用再生粗骨料取代碎石,高品质再生粗骨料可以使碎石混凝土的性能得到改善,而低品质再生粗骨料则降低碎石混凝土的性能,且再生粗骨料取代率不宜超过50%.%By using three different quality recycled coarse aggregates,this paper presents the effects of the replacement ratio of recycled coarse aggregate on the properties of work,mechanics and drying shrinkage of concrete.The results show that if the recycled coarse aggregate is used to replace gravel,the high-quality recycled coarse aggregate can improve the properties of gravel concrete and the low-quality recycled coarse aggregate can reduce the properties of gravel concrete,and the replacement ratio of recycled coarse aggregate should not exceed 50%.

  1. 再生粗骨料混凝土性能的研究%Researching of using waste concrete as coarse aggregate

    Institute of Scientific and Technical Information of China (English)

    段献智

    2012-01-01

    Use the waste concrete taken from several different locations and different service lives as the coarse aggregate,and make those coarse aggregate into the recycled concrete that have several different water-cement ratio and slump by different match,then test and compare the early properties of the fresh concrete.The results show that under the same conditions,the mobility of the recycled concrete poorer than the ordinary concrete.The setting time of the recycled concrete shorter than the ordinary concrete.And generally,the compressive strength of recycled concrete decreased with the recycled aggregate dosage increased.The higher water absorption of recycled aggregate,the lower compressive strength of recycled concrete.By the use of various complexed methods,we can get more higher compressive strength of the recycled concrete.The recycled coarse aggregate that mixed to the recycled aggregate concrete,in which the strength of the original concrete is low,has different effect to the recycled concrete with lower water-cement ratio and higher water-cement ratio.%将几种取自不同地点的废弃混凝土破碎制成粗骨料,然后通过不同搭配,配制成几种不同水灰比、坍落度的再生混凝土,并对其新拌混凝土早期的性能进行测试比较,研究结果表明,在相同条件下,再生混凝土的流动性比普通混凝土的差;再生混凝土的凝结时间比普通混凝土要短;再生混凝土的抗压强度一般随再生骨料掺量的增加而降低;吸水率高的再生骨料对应的再生混凝土强度低;通过各种方法的复合运用,可配得较高抗压强度的再生混凝土;混合再生骨料配制的再生混凝土,其中原始混凝土强度低的再生骨料,对低水灰比和高水灰比的再生混凝土有不同的影响效果。

  2. Development Law of Interfacial Microscopic Structure in Recycled Coarse Aggregate Concrete%再生粗集料混凝土界面微观结构的发展规律

    Institute of Scientific and Technical Information of China (English)

    耿欧; 陈辞; 顾荣军; 郑靖靖; 柴博士

    2012-01-01

    分别制作相同配合比的再生粗集料混凝土和普通混凝土试件.在养护龄期为3,7,14,28 d时,将再生粗集料混凝土试件切割,取样,然后对其内部不同界面微观结构进行扫描电镜观测;同时对再生粗集料混凝土和普通混凝土试件进行了抗压强度试验,观察了加载后再生粗集料混凝土试件内部裂纹的分布情况.结果表明:随着龄期的增长,再生粗集料混凝土各个界面过渡区都有不同程度的发展;天然粗集料-新砂浆界面过渡区发展相对缓慢;再生粗集料中老砂浆-新砂浆界面发展较快,老砂浆与新砂浆结合较好;再生粗集料中天然粗集料-老砂浆界面为混凝土浇筑前已存在的界面,并且存在着一定数量的微裂缝.再生粗集料混凝土3d抗压强度略高于普通混凝土,7,14,28 d抗压强度则与普通混凝土基本相当.荷载作用下,再生粗集料混凝土内部裂纹主要分布在天然粗集料-新砂浆界面以及天然粗集料-老砂浆界面处.%Recycled coarse aggregate concrete and ordinary concrete specimens were prepared with the same mix proportion. The recycled coarse aggregate concrete was sliced and samples were taken at the age of 3, 7, 14 , 28 d, and then their interfacial microscopic structures were observed by SEM. The compressive strength of recycled coarse aggregate concrete and ordinary concrete specimens were tested under axial loading. The distribution of internal cracks in recycled coarse aggregate concrete was also analyzed. It is concluded that with the age increasing, each interfacial transition zone(ITZ) in recycled coarse aggregate concrete has a certain degree of development. The development of ITZ between natural coarse aggregate and new mortar is relatively slow. The development of ITZ between old and new mortar in recycled coarse aggregate is the best. And the ITZ between natural coarse aggregate and old mortar in recycled coarse aggregate originally exists with

  3. Mechanism of fiber assembly; treatment of Aβ-peptide aggregation with a coarse-grained united-residue force field

    OpenAIRE

    Rojas, Ana; Liwo, Adam; Browne, Dana; Scheraga, Harold A.

    2010-01-01

    The mechanism of growth of fibrils of the β-amyloid peptide (Aβ) was studied by means of a physics-based coarse-grained united-residue (UNRES) model and molecular dynamics (MD) simulations. To identify the mechanism of monomer addition to an Aβ1–40 fibril, an unstructured monomer was placed at a 20 Å distance from a fibril template, and allowed to interact freely with it. The monomer was not biased towards the fibril conformation, by either the force field or the MD algorithm. By using a coar...

  4. Aggregation and network formation in self-assembly of protein (H3.1) by a coarse-grained Monte Carlo simulation

    Science.gov (United States)

    Pandey, R. B.; Farmer, B. L.

    2014-11-01

    Multi-scale aggregation to network formation of interacting proteins (H3.1) are examined by a knowledge-based coarse-grained Monte Carlo simulation as a function of temperature and the number of protein chains, i.e., the concentration of the protein. Self-assembly of corresponding homo-polymers of constitutive residues (Cys, Thr, and Glu) with extreme residue-residue interactions, i.e., attractive (Cys-Cys), neutral (Thr-Thr), and repulsive (Glu-Glu), are also studied for comparison with the native protein. Visual inspections show contrast and similarity in morphological evolutions of protein assembly, aggregation of small aggregates to a ramified network from low to high temperature with the aggregation of a Cys-polymer, and an entangled network of Glu and Thr polymers. Variations in mobility profiles of residues with the concentration of the protein suggest that the segmental characteristic of proteins is altered considerably by the self-assembly from that in its isolated state. The global motion of proteins and Cys polymer chains is enhanced by their interacting network at the low temperature where isolated chains remain quasi-static. Transition from globular to random coil transition, evidenced by the sharp variation in the radius of gyration, of an isolated protein is smeared due to self-assembly of interacting networks of many proteins. Scaling of the structure factor S(q) with the wave vector q provides estimates of effective dimension D of the mass distribution at multiple length scales in self-assembly. Crossover from solid aggregates (D ˜ 3) at low temperature to a ramified fibrous network (D ˜ 2) at high temperature is observed for the protein H3.1 and Cys polymers in contrast to little changes in mass distribution (D ˜ 1.6) of fibrous Glu- and Thr-chain configurations.

  5. Study on the workability and compressive strength of C30 recycled coarse aggregate concrete%C30再生粗骨料混凝土和易性和抗压强度研究

    Institute of Scientific and Technical Information of China (English)

    何锦云; 毛明明

    2011-01-01

    The C30 recycled coarse aggregate concrete is produced by use of the concrete blocks from the dismantled masonry structure buildings and the influence of recycled coarse aggregate replacement percentages, water cement ratio, and sand ratio on the 28 d compressive strength and workability are studied in orthogonal experiment design. The results show that the recycled coarse aggregate replacement percentages is the most primary factor effecting on 28 d compressive strength and workability; and with the recycled coarse aggregate replacement percentages increased, strength and workability decreased; It calls for using the percentages of 60% as recycled coarse aggregate, 0. 5 as water cement ratio and 36% as sand ratio to make reasonable design of mix proportions, we can obtain the recycled coarse aggregate concrete that its 28d compressive strength reach to 46. 3 Mpa.%以砖混结构建筑拆卸下来的混凝土块为原材料制备C30再生粗骨料混凝土,利用正交设计方法,研究了再生粗骨料取代率、水灰比、砂率对再生混凝土28 d抗压强度及和易性的影响.结果表明再生粗骨料取代率是影响混凝土28 d抗压强度及和易性的最主要因素;随着再生粗骨料取代率的增加,强度与和易性均下降;使再生粗骨料取代率为60%,水灰比为0.5,砂率为36%,通过合理的配合比可以配制出28 d强度达到46.3 MPa的混凝土.

  6. Mechanism of fiber assembly: treatment of Aβ peptide aggregation with a coarse-grained united-residue force field.

    Science.gov (United States)

    Rojas, Ana; Liwo, Adam; Browne, Dana; Scheraga, Harold A

    2010-12-01

    The growth mechanism of β-amyloid (Aβ) peptide fibrils was studied by a physics-based coarse-grained united-residue model and molecular dynamics (MD) simulations. To identify the mechanism of monomer addition to an Aβ(1-40) fibril, we placed an unstructured monomer at a distance of 20 Å from a fibril template and allowed it to interact freely with the latter. The monomer was not biased towards fibril conformation by either the force field or the MD algorithm. With the use of a coarse-grained model with replica-exchange molecular dynamics, a longer timescale was accessible, making it possible to observe how the monomers probe different binding modes during their search for the fibril conformation. Although different assembly pathways were seen, they all follow a dock-lock mechanism with two distinct locking stages, consistent with experimental data on fibril elongation. Whereas these experiments have not been able to characterize the conformations populating the different stages, we have been able to describe these different stages explicitly by following free monomers as they dock onto a fibril template and to adopt the fibril conformation (i.e., we describe fibril elongation step by step at the molecular level). During the first stage of the assembly ("docking"), the monomer tries different conformations. After docking, the monomer is locked into the fibril through two different locking stages. In the first stage, the monomer forms hydrogen bonds with the fibril template along one of the strands in a two-stranded β-hairpin; in the second stage, hydrogen bonds are formed along the second strand, locking the monomer into the fibril structure. The data reveal a free-energy barrier separating the two locking stages. The importance of hydrophobic interactions and hydrogen bonds in the stability of the Aβ fibril structure was examined by carrying out additional canonical MD simulations of oligomers with different numbers of chains (4-16 chains), with the fibril

  7. 再生粗骨料在高强泵送混凝土中应用的试验研究%Experimental study on application of recycled coarse aggregate in high strength pumped concrete

    Institute of Scientific and Technical Information of China (English)

    李超; 刘福田; 董全文; 谢慧东

    2011-01-01

    通过对再生粗骨料各项性能试验研究,分析再生粗骨料掺量对高强泵送混凝土性能的影响.通过进一步改善配合比,将再生粗骨料代替天然粗骨料掺量提高到30%,高强泵送再生粗骨料混凝土各项性能指标能够满足施工技术要求,并通过扫描电镜分析高强泵送再生租骨料混凝土的微观结构.%Based on the experimental study on the properties of recycled coarse aggregate,the effect of recycled coarse aggregate content on the performance of high-strength pumped concrete was analyzed. By further improving the mix,increasing the replacement ratio of recycled coarse aggregate content to 30%,a variety of indicators of high-strength pumped recycled aggregate concrete can meet the technical requirements for construction. By scanning electron microscopy,the microstructure of the high strength pumped recycled aggregate concrete was analyzed.

  8. Effect of fine to coarse aggregate ratio on the rheology and fracture energy of steel fibre reinforced self-compacting concretes

    Indian Academy of Sciences (India)

    Mert Yücel Yardimci; Bülent Baradan; Mehmet Alı Taşdemır

    2014-12-01

    In this study, the influence of aggregate grading and steel fibre properties on the flow properties and fracture energy of steel fibre reinforced self-compacting concrete (SFRSCC) has been investigated. Two types of hooked-end steel fibres at three different dosages (20, 40 and 60 kg/m3) were incorporated into self-compacting mixtures having similar paste contents but different fine to coarse aggregate (FA/CA) ratios (0.94, 1.72 and 2.50 by weight). Besides the flowability and passing ability of fresh concrete, the mechanical properties of hardened concrete including the fracture energy have also been investigated. The relations between flexural parameters and fibre orientation were established by image analysis technique. Test results showed that hooked-end steel fibre inclusion into the plain self-compacting concrete negatively affects the flowability and passing ability of themixture. Increasing FA/CA ratio enhances these rheological parameters and provides better fibre orientation. On the other hand, increasing FA/CA ratio decreases the fracture energy of plain SCC mixtures and the fibre incorporated series which were less affected from fibre inclusion follow the same trend with the plain SCC. The proper FA/CA ratio for the best rheological and mechanical performance depends on the fibre content, aspect ratio and their influence on the flowability of the mixture. In order to obtain better fibre orientation and hence higher fracture energy, relatively higher FA/CA ratios should be used when the fibre content and aspect ratio are relatively high.

  9. Modified test research of sericite schist coarse aggregates%绢云母片岩粗粒料改性试验研究

    Institute of Scientific and Technical Information of China (English)

    秦尚林; 杨兰强; 陈荣辉; 熊署丹

    2013-01-01

    The surface vibration compaction test, indoor heavy compaction test, interior California bearing ratio(CBR) test and modulus of resilience test have been carried out on sericite schist coarse aggregates and four modified soils, because the sericite schist belong to the soft rock, strength low, which is easy to make road collapse and pavement cracking when it as subgrade filling material. Test results shows that it is a big difference in the maximum dry density of sericite schist coarse aggregates by using heavy compaction test in contrast to the surface vibration compaction test. The results of maximum dry density is 2.01 g/cm3 by using heavy compaction test; but another is 1.92 g/cm3. The main reason is that due to particle breakage in sericite schist. The effects of the change of the optimum moisture content is not obvious for sericite schist coarse aggregates, as well as for four modified soils, which is beneficial to compaction. The modulus of resilience of sericite schist coarse aggregates is low, less than 32 MPa. However the modulus of resilience of modified soil have been remarkable improved, up to 50 MPa above all. The CBR both only have 3.7 when blend it with 20%red sandstone or 20%clay. But the CBR ascends obviously when to mix it with 3%or 5%cement. Sericit schist after chemical modification by adding 3%, 5%of cement can be used in the embank kment of highway 94 zone and 96 zone.%绢云母片岩属极软岩,强度低,直接作为路基填料难以压实,易造成路基沉陷、路面开裂等不良工程现象。通过对绢云母片岩及其4种改性方案进行表面振动压实试验、室内重型击实试验、室内CBR试验以及回弹模量试验研究,探讨绢云母片岩经改性后用作高速公路路基填料的适用性。试验表明,绢云母片岩最大干密度采用室内重型击实与表面振动压实试验结果相差较大,采用表面振动压实时为1.92 g/cm3,采用室内重型击实时为2.01 g/cm3。主要

  10. Effect of the Stone Powder Content in Coarse Aggregate on the Properties of C50 High Performance Concrete%粗骨料石粉含量对C50高性能混凝土性能的影响研究

    Institute of Scientific and Technical Information of China (English)

    安明喆; 苏阳; 王月; 韩松; 余自若

    2013-01-01

    The influences of stone powder contents in basalt gravel,limestone gravel and crushed pebble aggregates on the workability,mechanical properties and durability of C50 high performance concrete were studied through laboratory test methods.Results show that the slump flow of fresh concrete decreases with the increase of the stone powder content,the cohesion and water retention are also improved; but the flowability reaches the maximum when the stone powder content is 2 %,then decreases with the increase of stone powder content.The compressive strength and splitting tensile strength of C50 concrete with three kinds of aggregates all first increases,and then decreases with the increase of stone powder content,the compressive strength reaches the maximum when stone powder content is 2 %; moreover,the splitting tensile strength reaches the maximum when stone powder content is 4%.The type of coarse aggregate has a significant effect on the compressive modulus of elasticity of C50 concrete,the influence level is basalt concrete > limestone concrete > crushed pebble concrete when stone powder content is 4%.While the stone powder content is in the range of 0~6%,the electric flux of C50 concrete with three kinds of coarse aggregates are all below 1 000 C,which indicates the compactness of these concretes are satisfactory.The frost resistance of C50 concrete with 4% stone powder content presents that basalt is the best while crushed pebble is the worst.%运用室内试验方法,研究玄武岩、石灰岩碎石和碎卵石粗骨料中石粉含量对C50高性能混凝土工作性、力学性能和耐久性的影响.结果表明:新拌混凝土的扩展度随石粉含量的增加而减小,其黏聚性和保水性得到改善,而其流动性在石粉含量为2%时达到最大,之后随石粉含量的增加而减小;3种粗骨料的C50混凝土的抗压强度和劈裂抗拉强度均随石粉含量的增加呈先增大后减小的规律,抗压强度

  11. 再生粗骨料混凝土早期收缩性能试验研究%Experimental research on early shrinkage of recycled coarse aggregate concrete

    Institute of Scientific and Technical Information of China (English)

    张兴才; 李洪明; 朱磊

    2015-01-01

    The influences of water - cement ratio,replacement ratio of recycled coarse aggregate,water reducer and fly ash on early dr-ying shrinkage of recycled concrete were investigated by experiments.Research results show that the shrinkage ratio and the water loss ratio of recycled concrete increase with the water - cement ratio and replacement ratio of recycled coarse aggregate,the rates of the shrinkage and water loss reach to the maximum in the first 7 days,and water reducer and fly ash could effectively reduced the shrinkage of recycled concrete.The model for drying shrinkage of recycled concrete with 100% replacement of the recycled coarse aggregate is es-tablished according to experiment results,and the calculated values of the shrinkage ratio of recycled coarse aggregate concrete are in good agreement with the test values obtained by other researchers.%通过试验研究水灰比、再生粗骨料取代率、减水剂和粉煤灰对再生混凝土早期干缩性能的影响。研究结果表明,再生混凝土的早期干缩率和失水率均随着水灰比和取代率的增大而增大;再生混凝土在龄期7 d 内干缩速率和失水速率最大;掺入减水剂和粉煤灰可以有效地控制再生混凝土的干缩。根据试验结果建立了再生粗骨料取代率为100%的再生混凝土早期干缩计算模型,该模型计算结果与他人试验结果吻合较好。

  12. On influence of coarse aggregate on concrete performance and its control in production%粗集料对混凝土性能的影响及生产中的控制

    Institute of Scientific and Technical Information of China (English)

    刘钢; 陈明宇

    2012-01-01

    By theoretic analysis and experiments,the paper discusses the indexes of the coarse aggregate,including the mud content,the grain type and the grain composition,has the analysis of economic cost of the concrete by adopting different coarse aggregates,so as to optimize the concrete mix proportion and provide the direction for the selection of the coarse aggregate and the design of the mix proportion in the factual concrete production.%通过理论分析和试验,讨论了粗集料的含泥量、粒型和颗粒级配等指标对混凝土性能的影响,并对不同使用粗集料的混凝土进行经济成本分析,以实现混凝土配合比的优化,为实际混凝土生产中粗集料的选择和配合比设计提供指导。

  13. Study of potential advantages of pre-soaking on the properties of pre-cast concrete made with recycled coarse aggregate

    Directory of Open Access Journals (Sweden)

    Sánchez-Roldán, Z.

    2016-03-01

    Full Text Available Recycled aggregate (RA from construction and demolition waste is traditionally used for the manufacture of concrete for different applications. Due primarily to high water content required by RA, the quality of the concrete is determined by the amount of replacement RA. The aim of this study is to determine if RA pre-soaking enhances the properties of pre-cast concrete for street furniture, with low mechanical and structural requirements, in which 100% of the coarse fraction is replaced. The results of physical and mechanical tests performed on concrete specimens in which the RA was pre-soaked using five different methods applied are compared with a reference concrete sample and a concrete sample made with non-pre-soaked RA. The results show that non-pre-soaked RA offers improved physical-mechanical properties for pre-cast concrete, except for the workability; problems arising from poorer workability could be improved with the use of plasticizers, which can be easily included in the production process.El árido reciclado (AR procedente de residuos de construcción y demolición se utiliza tradicionalmente en la elaboración de hormigón para diferentes aplicaciones. Debido principalmente al mayor contenido en agua requerido por el AR, la calidad del hormigón está determinada por la cantidad de AR reemplazado. El objetivo de este estudio es determinar si el AR premojado mejora las propiedades del hormigón prefabricado para mobiliario urbano, con bajas exigencias mecánicas y estructurales, en el que se sustituye el 100% de la fracción gruesa. Los resultados de los ensayos físicos y mecánicos realizados sobre muestras de hormigón en las cuales el AR se ha premojado usando cinco métodos diferentes se han comparado con una muestra de hormigón de referencia y una muestra de hormigón fabricada con AR no premojado. Los resultados muestran que el AR no premojado proporciona propiedades físico-mecánicas mejoradas en el hormigón prefabricado

  14. 面向工程的再生混凝土与钢筋粘结性能研究%Experimental Investigation of the Bond Performance of RAC by Using Coarse Aggregates From Different Origins

    Institute of Scientific and Technical Information of China (English)

    施养杭; 吴泽进; 彭冲

    2012-01-01

    To study the effect of recycled coarse aggregates of different origins on recycled concrete, four typical sources of recycled concrete, such as old house dismantlement, high-strength pile, municipal engineering and scientific research, are chosen in the study. The four kinds of waste concrete are broken into four kinds of recycled coarse aggregates. Meanwhile, four kinds of replacement ratio, two mineral admixtures, steel bars of two strength grades and three diameters are considered. Through the method of orthogonal test, 17 groups of Bond anchorage specimens are compounded. Through the center pull-out tests, the maximum average bond strengths are measured respectively, then compared and analyzed. Results show that the strength grade of steel bars is the most main factor which influences the maximum average bond strength of the recycled concrete, while the recycled coarse aggregate replacement ratio is the second. The recycled coarse aggregate origin, the diameter of steel bars and the mineral admixture all have low effect on the maximum average bond strength of the recycled concrete.%为探究RAG(再生混凝土)与钢筋的粘结性能,选取最具代表性的旧房拆迁、高强桩基、市政工程、科学研究等四种废混凝土,经加工而成相应粗骨料,并考虑四种取代率、二种矿物掺合料、二种等级和三种直径的钢筋,采用正交试验法,制作17组试件.经拔出试验,分别测出最大平均粘结强度.结果表明:影响RAC最大平均粘结强度的主要因素依次为钢筋等级、再生粗骨料取代率、再生粗骨料来源、钢筋直径、矿物掺合料.

  15. Study on relationships between strength indexes of recycled glass coarse aggregate concrete%再生玻璃粗骨料混凝土强度指标换算关系研究

    Institute of Scientific and Technical Information of China (English)

    李爱飞; 梁炯丰; 罗锟

    2014-01-01

    Based on the experimental data,the relationships between the cubic compressive strength and other strength are obtained.The results showed that the every strength of waste glass recycled coarse aggregate concrete was lower than ordinary concrete and the inter-re-lationships of strength indexes of waste glass recycled coarse aggregate concrete is different from that ordinary concrete.%在试验数据的基础上,通过统计回归,初步给出了再生玻璃粗骨料混凝土立方体抗压强度与其他强度指标之间的换算关系。试验结果表明:再生玻璃粗骨料混凝土各种强度均比普通混凝土要低,其强度换算关系并不同于普通混凝土。

  16. 掺橡胶颗粒的玄武岩纤维轻骨料混凝土力学性能研究%Research on mechanical properties of basalt fiber reinforced lightweight aggregate concrete with incorporation of rubber particles

    Institute of Scientific and Technical Information of China (English)

    李京军; 牛建刚; 朱聪; 吴运超

    2015-01-01

    分别研究了不同掺量短切玄武岩纤维对轻骨料混凝土及橡胶颗粒代替部分细集料后的轻骨料混凝土的抗压、劈裂抗拉和抗折性能的影响。试验研究表明:玄武岩纤维能有效提高轻骨料混凝土的抗压强度、劈裂抗拉强度和抗折强度;当在轻骨料混凝土中掺入橡胶颗粒后,抗压强度随着纤维掺量的增加呈递减趋势,劈裂抗拉强度随着纤维掺量的增加不显著变化,抗折强度随着纤维掺量的增加呈现先降低后增加的变化趋势;掺入橡胶颗粒的轻骨料混凝土的三项力学指标数值均低于对应的不掺橡胶颗粒的轻骨料混凝土。%The influence of chopped basalt fiber volume fraction on the compressive properties,the flexural properties and tensile split-ting strength of lightweight aggregate concrete and lightweight aggregate concrete with part of the fine aggregate replaced by rubber par-ticles were investigated by experiments.Results show that basalt fiber can effectively improve the compressive strength,splitting tensile strength and flexural strength of lightweight aggregate concrete After the rubber particles were added into lightweight aggregate con-crete,with the increase of fiber content,the compressive strength show a trend of decline,splitting tensile strength changed not signifi-cantly,and flexural strength showed an upward trend after the first drop.The three mechanics indicators of lightweight aggregate con-crete adding rubber particles are lower than lightweight aggregate concrete with no incorporation of rubber particles.

  17. 再生混凝土粗骨料物理性能的试验分析%Physical Properties Test Analysis of Recycled Concrete Coarse Aggregate

    Institute of Scientific and Technical Information of China (English)

    秦拥军; 付明阳; 崔思贤

    2012-01-01

    Advantages and disadvantages of the performance of concrete aggregate will directly affect the quality of concrete. Based on the basic physical performance test comparison analysis of the recycled concrete aggregate and natural aggregate , in comparison with the natural concrete aggregate, the recycled concrete aggregate has higher water absorption, smaller apparent density and bulk density, and larger crushed indicators. The paper can provide a reference to enable the recycled concrete made to meet the required working performance, which is favorable to the use of construction waste and the application of "green building" .%混凝土骨料工程性能的优劣将直接影响到混凝土的质量.通过对再生混凝土骨料和天然骨料的基本物理性能试验对比分析,得到再生混凝土骨料较天然卵石骨料的吸水率高、表观密度及堆积密度小、压碎指标大;为配制符合工程性能要求的再生混凝提供参考依据,促进建筑废料的利用和“绿色建材”的应用.

  18. 再生粗骨料混凝土耐久性试验研究%Experimental study on durability of recycled coarse aggregate concrete

    Institute of Scientific and Technical Information of China (English)

    霍艳华; 毛添钿; 熊进刚

    2012-01-01

    对再生混凝土进行了碳化、循环冻融、抗渗和复合因素下的耐久性试验研究,比较了再生混凝土和普通混凝土的碳化速度、抗冻、抗渗等耐久性能.对再生混凝土的冻融和抗渗复合耐久性能进行了初步试验研究,结果表明,再生混凝土对这种叠加损伤更为敏感,受到的破坏也更大.%The experiments on carbonation resistance, freezing-thawing cycle, impermeability and durability under multi-factors conditions of recycled aggregate concrete are researched, the carbonation speed, freezing-thawing resistance and impermeability durability of the recycled aggregate concrete and the ordinary concrete are compared. The preliminary experimental research of freeze- thaw and anti-permeability composite durability of recycled aggregate concrete has carried on, the results show that the superposition damage of recycled aggregate concrete is more sensitive,and the damage is greater.

  19. 再生火山岩骨料混凝土抗压强度及干缩性能试验%Experimental study on compressive strength and dry-shrinkage property of recycled volcanic rock coarse aggregate concrete

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    A recycled volcanic rock coarse aggregate concrete is developed,which the aggregate replacement rate is 100%. The compressive strength and dry-shrinkage performance of recycled volcanic rock aggregate concrete are studied. The results show that the compressive strength of recycled concrete after curing 28 days than that of normal concrete is reduced by about 13%,and the dry-shrinkage strain is about 1. 25 times of the reference concrete.%配置了骨料取代率为100%的再生火山岩粗骨料混凝土,并对其抗压强度和干缩性能进行试验研究,结果表明:再生火山岩混凝土28 d抗压强度比基准混凝土抗压强度降低约13%;干燥收缩应变约为基准混凝土的1.25倍。

  20. Application of Basalt Aggregate in the RCC of Jin'anqiao Hydropower Station%金安桥水电站玄武岩骨料碾压混凝土应用研究

    Institute of Scientific and Technical Information of China (English)

    康小春; 张改香

    2011-01-01

    金安桥水电站大坝为玄武岩骨料碾压混凝土重力坝.玄武岩骨料属火成岩,密度大、质地硬脆,造成碾压混凝土用水量、拌和物性能与石灰岩骨料碾压混凝土相比,差别很大.通过对玄武岩骨料碾压混凝土性能试验研究,配合比设计采取外掺石粉代砂、提高外加剂掺量、低VC值,施工过程中对VC值进行动态控制等技术措施,有效地改善了玄武岩骨料碾压混凝土的可碾性、液化泛浆和层间结合质量,方便大坝温度控制,提高抗裂性能.机口混凝土性能检测和钻孔取芯及压水检查表明,玄武岩骨料碾压混凝土的强度、变形性和耐久性均满足设计要求,整体抗渗性能良好.%The Jin'anqiao RCC gravity dam uses basalt as concrete aggregate. As the high density, hardness and brittleness of basalt, the water consumption and the mixture performance of RCC with basalt aggregate is different to the RCC with limestone aggregate. According to the experimental studies on RCC performance, the mix proportion design was improved by taking limestone powder instead of sand, increasing additive content and lowering VC value, and the VC value was also dynamically controlled in the construction. These measures effectively improve the compactibility, bleeding and interlayer bonding of RCC, and contribute to control the temperature rise and improve crack resistance of dam. The performance tests for concrete on the outlet of mixer, core samplings and water pressure tests show that the strength, deformation and durability of RCC meet design requirements and the overall impermeability is good.

  1. 利用营建剩余土石方开发冷压型再生粗骨料之可行性%Feasibility of Using Construction Residual Soils to Develop Cold-Pressing Recycling Coarse Aggregates

    Institute of Scientific and Technical Information of China (English)

    蔡志达; 张建智; 李隆盛; 张祖恩

    2012-01-01

    The cold-pressing technique, which incorporates the principles of cement chemistry and composite material was employed to produce the recycling coarse aggregates using B2-3, B3, B4, and B6 categories construction residual soils with extremely low utilization rate and poor properties so as to raise the utilization rate and value of the above-mentioned construction residual soils. The results show that the specific gravity of recycling coarse aggregate is about 1. 80 in the oven-dry(OD) state and 2. 05 in the saturated-surface-dry (SSD) state; the absorption capacity is approximately 15. 5%(by mass); the bulk density (I. E. Unit weight) is 1 103 to 1 216 kg/m3; the air void is about 35. 3% (by volume); the particle cylindrical crushing strength ranges from 17. 06 to 23. 33 Mpa; other characteristics meets reguirement set forth in ASTM C33. For this reason, the developed recycling cold-pressing coarse aggregates can not only meet the specifications for green building materials, but can also be used to reduce the energy consumption and CO2 emission resulted from producing the sintering recycling aggregates.%根据材料互制性,配合水泥化学,并导入复合材料的观念,采用冷压技术,开发以性质较差且再利用率或再生性甚低的B2-3,B3,B4,B6类营建剩余土石方为母材的再生粗骨料,期望提高其再利用率及经济价值,试验结果显示,采用冷压技术所制作的再生粗骨料性质为:烘干相对密度约1.80;面干内饱和相对密度约2.05;吸水率约15.5%(质量分数);堆积密度为1 103~1 216 kg/m3;空隙率约35.3%(体积分数);筒压强度为17.06~23.33MPa;其他性质亦符合ASTM C33规范要求.因此利用营建剩余土石方及冷压技术所开发的再生骨料,不仅符合再生绿色建材的精神,亦可降低生产烧结型再生骨料所消耗之能源与CO2排放.

  2. Self-assembly dynamics for the transition of a globular aggregate to a fibril network of lysozyme proteins via a coarse-grained Monte Carlo simulation

    Directory of Open Access Journals (Sweden)

    R. B. Pandey

    2015-09-01

    Full Text Available The self-organizing dynamics of lysozymes (an amyloid protein with 148 residues with different numbers of protein chains, Nc = 1,5,10, and 15 (concentration 0.004 – 0.063 is studied by a coarse-grained Monte Carlo simulation with knowledge-based residue-residue interactions. The dynamics of an isolated lysozyme (Nc = 1 is ultra-slow (quasi-static at low temperatures and becomes diffusive asymptotically on raising the temperature. In contrast, the presence of interacting proteins leads to concentration induced protein diffusion at low temperatures and concentration-tempering sub-diffusion at high temperatures. Variation of the radius of gyration of the protein with temperature shows a systematic transition from a globular structure (at low T to a random coil (high T conformation when the proteins are isolated. The crossover from globular to random coil becomes sharper upon increasing the protein concentration (i.e. with Nc = 5,10, with larger Rg at higher temperatures and concentration; Rg becomes smaller on adding more protein chains (e.g. Nc = 15 a non-monotonic response to protein concentration. Analysis of the structure factor (S(q provides an estimate of the effective dimension (D ≥ 3, globular conformation at low temperature, and D ∼ 1.7, random coil, at high temperatures of the isolated protein. With many interacting proteins, the morphology of the self-assembly varies with scale, i.e. at the low temperature (T = 0.015, D ∼ 2.9 on the scale comparable to the radius of gyration of the protein, and D ∼ 2.3 at the large scale over the entire sample. The global network of fibrils appears at high temperature (T = 0.021 with D ∼ 1.7 (i.e. a random coil morphology at large scale involving tenuous distribution of micro-globules (at small scales.

  3. 大草坝玄武岩料场砂石加工系统设计%Study on the Dacao Dam basalts quarry planning and aggregate processing system design

    Institute of Scientific and Technical Information of China (English)

    郭磊

    2015-01-01

    通过对料场的储量、需求量、剥采比等技术指标进行准确计算分析,经技术、经济等方面的优化,选择满足工程特性的大草坝玄武岩料场开采方案和砂石加工关键工艺。大草坝料场及砂石加工系统规划设计方案的科学布置和合理选择,满足工程施工建设高峰用料需求,为施工质量和进度控制奠定了夯实基础。%Based on accurate analysis and calculation for the quarry reserves, demand, stripping ratio and other technical indicators, and through the economic & technical comparisons, the Dacao Dam basalts quarry exploiting plan and the key technology of aggregate processing which can meet the engineering characteristics has been approved. Through the scientific layout planning and reasonable selection for the planning and design scheme , it can meet the engineering construction materials using peak demand, and provide a solid foundation for the construction quality and progress control.

  4. Study on the Dacao Dam basalts quarry planning and aggregate processing system design%大草坝玄武岩料场砂石加工系统设计

    Institute of Scientific and Technical Information of China (English)

    郭磊

    2015-01-01

    通过对料场的储量、需求量、剥采比等技术指标进行准确计算分析,经技术、经济等方面的优化,选择满足工程特性的大草坝玄武岩料场开采方案和砂石加工关键工艺。大草坝料场及砂石加工系统规划设计方案的科学布置和合理选择,满足工程施工建设高峰用料需求,为施工质量和进度控制奠定了夯实基础。%Based on accurate analysis and calculation for the quarry reserves, demand, stripping ratio and other technical indicators, and through the economic & technical comparisons, the Dacao Dam basalts quarry exploiting plan and the key technology of aggregate processing which can meet the engineering characteristics has been approved. Through the scientific layout planning and reasonable selection for the planning and design scheme , it can meet the engineering construction materials using peak demand, and provide a solid foundation for the construction quality and progress control.

  5. Investigation of the Interfacial Transition Zone between Aggregate-Cement Paste by AC Impedance Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    KONG Lijuan; HOU Lirong; WANG Yuhua; SUN Guowen

    2016-01-01

    Three different types and sizes of coarse aggregate were chosen, and the alternating current (AC) impedance of cement paste samples with and without aggregate was measured at different curing ages. Based on Song’s equivalent circuit model, the electrical properties from the AC impedance results were obtained, and the resistance of connected pores RCCP was used to characterize the microstructure of the interfacial transition zone (ITZ). The results show that the RCCP of concrete sample with aggregate is lower than that of cement paste sample, which indicates that the introduction of aggregate in cement paste makes the ITZ porous. Furthermore, for the same type of aggregate, an increase in particle size leads to a more porous ITZ, which accounts for the “water effect” and a larger aggregate would accumulate a thicker water iflm around it. In addition, for the same size of aggregate, the physical interaction between aggregate and cement paste is dominant in early age, and the microstructure of the ITZ around limestone aggregate is denser, which mainly depends on its rough surface and high water absorption. However, the microstructures of the ITZ around granite and basalt aggregates are denser in later age, which may be due to their higher chemical activity, and the chemical interaction between them and cement paste resulting in the generation of more hydrates. AC impedance spectroscopy thus proves to be powerful for evaluation of the microstructure of the ITZ.

  6. 机制砂再生粗骨料混凝土无腹筋梁抗剪性能研究%Experimental Research on Shear Capacity of Manufactured Sand and Recycled Coarse Aggregate Concrete Beams without Web Reinforcement

    Institute of Scientific and Technical Information of China (English)

    赵顺波; 赵兵; 李广欣; 潘丽云

    2015-01-01

    分析了不同剪跨比情况下机制砂再生粗骨料混凝土无腹筋梁的斜截面开裂形态与开裂剪力、斜截面破坏形态和受剪承载力.采用普通钢筋混凝土无腹筋梁斜截面开裂剪力和受剪承载力计算公式,对试验结果进行了预测分析.采用现行《混凝土结构设计规范》(GB 50010—2010)规定的钢筋混凝土梁受剪承载力计算公式,对试验结果进行了可靠性分析.结果表明,机制砂再生粗骨料混凝土无腹筋梁的斜截面开裂剪力和受剪承载力随剪跨比的增大而减小,可采用普通钢筋混凝土无腹筋梁的相应计算公式进行预测分析和设计计算.%The shear cracking state and shear force, and the shear failure state as well as the shear capacity of the manufactured sand and recycled coarse aggregate concrete ( MSRCAC) beams without web reinforcement in different status of shear-span ratio are ana-lyzed. The test results are forecasted by using the formulas of shear cracking force and shear capacity of ordinary reinforced concrete beams, and the reliability of shear capacities of test beams are analyzed by using the formulas specified in current design code for ordi-nary reinforced concrete beams. The results show that the shear cracking force and shear capacity of MSRCAC beams without web rein-forcement decrease with the increase of the shear-span ratio, which can be forecasted and designed by using the relevant formulas of or-dinary reinforced concrete beams without web reinforcement.

  7. Experiment of mix proportion and mechanical performance about concrete using steel slag coarse aggregates%钢渣代碎石混凝土配合性能及力学性能的试验

    Institute of Scientific and Technical Information of China (English)

    石东升; 冯倩; 丁晓宇; 王安

    2015-01-01

    对转炉钢渣代碎石混凝土和普通碎石混凝土做了对比试验研究,讨论了不同代碎石率及不同水胶比条件下钢渣粗骨料混凝土的配合性能和力学性能。试验结果表明:在相同配合比条件下,要配出与普通混凝土流动性相同的钢渣代碎石混凝土,需增大水和减水剂的用量;且随着水胶比的增大,所需水和减水剂用量逐渐增多;混凝土拌合物含气量随钢渣代碎石率的增加而增大。与普通混凝土相比,钢渣代碎石混凝土抗压强度早期增长率基本相同,龄期90 d 后钢渣代碎石率越高,抗压强度增长越快;且随着水胶比的降低,钢渣代碎石混凝土后期抗压强度增长率更高;钢渣代碎石混凝土龄期90 d 的劈裂抗拉强度与普通混凝土相比较没有明显的差异。%The mix proportion and mechanical performance of steel slag as coarse aggregates in the condition of different generation of gravel ratio and different water binder ratio was discussed,which did the contrast test researched between the converter steel slag con-crete and ordinary concrete.The results show that the amount of water and water reducing agent are needed to increase to produce the same flowing property as the ordinary concrete of steel slag concrete.And with the addition of the water binder ratio,the dosage of water and water reducing agent are gradually increasing.The concrete mixture air content increases with the increasing of the generation of gravel ratio.Compared with the ordinary concrete,the early stage compressive strength of steel slag concrete has the same rate and the higher the ratio of steel slag generation of rubble in 90 d,the compressive strength of the grow faster.With the reduction of water binder ratio,the compressive strength′s aigrowth rate is higher in the late stage.There are few significant differences in the 90d splitting tensile strength between steel slag concrete and ordinary concrete.

  8. 粗集料棱角性对水稳河滩料强度和干缩特性影响的试验研究%Experimental Study on Influences of Angularity of Coarse Aggregates on Strength and Dry-shrinkage Characteristic of Cement Stabilized Beach Materials

    Institute of Scientific and Technical Information of China (English)

    王火明; 杨敏; 符德省; 王秀

    2013-01-01

    针对粗集料棱角性对水稳混合料路用性能(强度和干缩特性)的影响展开试验研究.试验结果表明,粗集料不宜含有较多的浑圆状颗粒和针片状颗粒,其松装空隙率宜控制在43% ~45%,振装空隙率宜控制在41% ~43%.此外,全部破碎颗粒中混入不超过20%的浑圆状颗粒可以有效减少松(振)装空隙率和针片状含量,对提高混合料无侧限抗压强度有利;含有不超过20%浑圆状颗粒的粗集料与全部破碎的粗集料相比,其劈裂强度相差不大.干缩试验表明,拐点失水率与合成矿料骨架空隙率有一定关系,骨架空隙越大,拐点失水率也越大;当粗集料中含有较多的浑圆状颗粒时,其干缩系数拐点失水率相对较小.%This paper develops experimental study on influences of angularity of coarse aggregates on road performance (strength and dry-shrinkage characteristic) of cement stabilized mixtures. The results of experiment indicate that coarse aggregates should not contain many round, needle-like and flaky particles, the loose-packed voidage should be controlled in the range of 43% ~ 45% and the vibratory-packed voidage in the range of 41%~43%. In addition, mixture of no more than 20% round particles in all crushed particles can effectively reduce loose ( vibratory) -packed voidage and contents of needle-like and flaky particles, in favor of improving unconfined compressive strength of mixtures; in comparison with fully crushed coarse aggregates, the splitting strength of coarse aggregates with content of round particles no more than 20% is slightly different. The dry-shrinkage test shows that the knee-point rate of water loss is certainly related to framework voidage of composite mineral materials, the larger the framework voidage, the higher the knee-point rate of water loss; when coarse aggregates contain more round particles, the knee-point rate of water loss of its dry-shrinkage coefficient is relatively small.

  9. Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars.

    Science.gov (United States)

    Abdul-Majid, S; Othman, F

    1994-03-01

    Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples.

  10. Petrology of the Apollo 12 pigeonite basalt suite

    International Nuclear Information System (INIS)

    A comparative petrologic study of the Apollo 12 pigeonite basalt suite has been undertaken to answer the following questions: (1) What are the textural and petrologic variations within the pigeonite suite. (2) Are these variations consistent with the hypothesis that the pigeonite basalts are related by crystal fractionation to the olivine basalts. Texturally, the pigeonite basalts range from porphyritic samples with a very fine-grained variolitic groundmass to coarse-grained microgabbro samples with ophitic to graphic textures. The abundances of olivine and Cr-spinel continuously decrease with increasing grain size, whereas the abundances of plagioclase and ilmenite steadily increase. Petrologically, increasing grain size is accompanied by increased Ca in plagioclase, increased Fe in pyroxene, olivine, and spinel, and less Al, Ti, and Cr in pyroxene. All of these changes, including the differences in bulk chemistry can be explained by near-surface fractionation of olivine, pigeonite, and Cr-spinel with the compositions of the observed phenocryst phases

  11. Test on Bond Behavior of Concrete Filled Square Steel Tubes Between Steel and Recycled Coarse Aggregate Concrete%方钢管再生混凝土界面粘结性能试验

    Institute of Scientific and Technical Information of China (English)

    赵强

    2016-01-01

    对8根钢管再生混凝土柱界面粘结性能进行研究,探讨再生骨料取代率及再生混凝土强度对钢管再生混凝土界面粘结性能的影响。结果表明:钢管再生混凝土荷载-滑移曲线大致经历无滑移阶段、应力上升段、应力下降段等3个阶段,不同再生骨料取代率的钢管再生混凝土荷载-滑移曲线具有类似的特征;再生骨料的取代率对钢管与再生混凝土界面粘结强度影响显著,再生骨料取代率越高,界面粘结强度越低;再生混凝土强度对钢管再生混凝土强度有一定影响,随着再生混凝土强度提升,粘结强度逐渐增加,但增幅逐渐降低。%To investigate the influence of different ratio and strength grade of recycled aggregate concrete on interfacial bond performance of concrete filled steel tube,the bond behavior of eight pieces of recycled aggregate concrete-filled steel tube is studied.The results indicate that load-slip curve of recycled aggregate concrete-filled steel tube consists of three stages,including the no slip stage,stress increase stage and stress decrease stage.The load-slip curves steel with differ-ent recycled aggregate replacement ratios have similar characteristics.The replacement ratio of recycled aggregate has a significant negative effect on the bond strength.With the increase of the replacement ratio of recycled aggregate,the bond strength decreases gradually.The strength of recycled concrete has a certain effect on the bond strength.With the in-crease of the strength of recycled aggregate concrete,the bond strength increases gradually,but the increase percent re-duces gradually.

  12. Experimental investigation of coarse-grained particles in pipes

    OpenAIRE

    Vlasák, P.; Chára, Z.; Konfršt, J. (Jiří); Kysela, B. (Bohuš)

    2013-01-01

    The effect of solid concentration and mixture velocity on the flow behaviour and pressure drops of coarse-grained particle-water mixtures in the turbulent flow was experimentally investigated. Concentration distribution in the pipe cross-section was also studied. Graded basalt pebbles as a model of solid particles were studied on an experimental pipe loop with horizontal, vertical, and inclined sections of smooth stainless steel pipes of inner diameter D = 100 mm. The study revealed that the ...

  13. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    OpenAIRE

    Hisham Qasrawi; Iqbal Marie

    2013-01-01

    The effect of using recycled concrete aggregates (RCA) on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates...

  14. Experimental investigation of coarse particles-water mixture flow in horizontal and inclined pipes

    OpenAIRE

    Vlasák, Pavel; Chára, Zdeněk; Krupička, Jan; Konfršt, Jiří

    2014-01-01

    The effect of solid concentration and mixture velocity on the flow behaviour, pressure drops, and concentration distribution of coarse particle–water mixtures in horizontal, vertical, and inclined smooth stainless steel pipes of inner diameter D = 100 mm was experimentally investigated. Graded basalt pebbles were used as solid particles. The study revealed that the coarse-grained particle-water mixtures in the horizontal and inclined pipes were significantly stratified. The solid particle...

  15. Effect of Coarse Aggregate on Durability of C55 Concrete%粗骨料品种对 C55耐久混凝土性能的影响

    Institute of Scientific and Technical Information of China (English)

    苏祖平; 叶小吁; 陈露一; 欧阳华林

    2014-01-01

    The bridge on the Huangling-Hancheng-Houma Railway is a post-tensioned pres-tressed concrete simply supported T-shaped girder bridge .The main girder was prefabricated in the workshop ,the strength of concrete was required being C55 and the electric flux of the concrete aging 56 d being no less than 1 000 C .Given the technical indexes ,transportation distance and cost of the crushed stones ,the biotite granodiorite gravels and crystalline limestone gravels were con-sidered .In order to select out the type of gravels that can meet the requirements so as to prepare the concrete which suits the project demands ,the two kinds of aggregates aforementioned were used to prepare C55 concrete ,with the intention of testing the properties of the mixing materials , mechanical behavior and resistance to chloride ion penetration of the concrete .In addition the opti-cal microscope was used to analyze the microstructure of the two kinds of aggregates ,The results indicate that the elastic modulus and electric flux of the C55 concrete with biotite granodiorite gravels can not meet the railway code requirements ,but those of the C55 concrete with crystalline limestone gravels can meet the railway code requirements .%黄韩侯铁路上的桥梁设计为后张法预应力混凝土T形简支梁,主梁在制梁场预制,要求混凝土强度等级为C55,56 d混凝土的电通量≤1000 C。考虑碎石的技术指标、运距和成本因素,选取了黑云母花岗闪长岩碎石和结晶灰岩碎石2种粗骨料。为优选出满足要求的碎石,配制满足工程要求的混凝土,采用这2种粗骨料配制C55混凝土,对混凝土的拌合物工作性、力学性能及抗氯离子渗透性能等进行试验,并采用光学显微镜对2种粗骨料的微观结构进行了分析。结果表明:使用黑云母花岗闪长岩碎石配制的C55耐久混凝土的弹性模量及电通量不能满足铁路规范要求,而使用结晶灰岩碎石配制的C55耐久

  16. Coarse Grained Quantum Dynamics

    CERN Document Server

    Agon, Cesar; Kasko, Skyler; Lawrence, Albion

    2014-01-01

    We consider coarse graining a quantum system divided between short distance and long distance degrees of freedom, which are coupled by the Hamiltonian. Observations using purely long distance observables can be described by the reduced density matrix that arises from tracing out the short-distance observables. The dynamics of this density matrix is that of an open quantum system, and is nonlocal in time, on the order of some short time scale. We describe these dynamics in a model system with a simple hierarchy of energy gaps $\\Delta E_{UV} > \\Delta E_{IR}$, in which the coupling between high-and low-energy degrees of freedom is treated to second order in perturbation theory. We then describe the equations of motion under suitable time averaging, reflecting the limited time resolution of actual experiments, and find an expansion of the master equation in powers of $\\Delta E_{IR}/\\Delta E_{UV}$, in which the failure of the system to be Hamiltonian or even Markovian appears at higher orders in this ratio. We com...

  17. Why Hexagonal Basalt Columns?

    Science.gov (United States)

    Hofmann, Martin; Anderssohn, Robert; Bahr, Hans-Achim; Weiß, Hans-Jürgen; Nellesen, Jens

    2015-10-01

    Basalt columns with their preferably hexagonal cross sections are a fascinating example of pattern formation by crack propagation. Junctions of three propagating crack faces rearrange such that the initial right angles between them tend to approach 120°, which enables the cracks to form a pattern of regular hexagons. To promote understanding of the path on which the ideal configuration can be reached, two periodically repeatable models are presented here involving linear elastic fracture mechanics and applying the principle of maximum energy release rate. They describe the evolution of the crack pattern as a transition from rectangular start configuration to the hexagonal pattern. This is done analytically and by means of three-dimensional finite element simulation. The latter technique reproduces the curved crack path involved in this transition.

  18. Microcanonical thermostatistics of coarse-grained proteins with amyloidogenic propensity

    CERN Document Server

    Frigori, Rafael B; Alves, Nelson A

    2012-01-01

    The formation of fibrillar aggregates seems to be a common characteristic of polypeptide chains, although the observation of these aggregates may depend on appropriate experimental conditions. Partially folded intermediates seem to have an important role in the generation of protein aggregates, and a mechanism for this fibril formation considers that these intermediates also correspond to metastable states with respect to the fibrillar ones. Here, using a coarse-grained (CG) off-lattice model, we carry out a comparative analysis of the thermodynamic aspects characterizing the folding transition with respect to the propensity for aggregation of four different systems: two isoforms of the amyloid $\\beta$-protein, the Src SH3 domain, and the human prion proteins (hPrP). Microcanonical analysis of the data obtained from replica exchange method (REM) is conducted to evaluate the free-energy barrier and latent heat in these models. The simulations of the amyloid $\\beta$ isoforms and Src SH3 domain indicated that th...

  19. Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

    OpenAIRE

    Yuanchen Guo; Jueshi Qian; Xue Wang; Zhengyi Yan; Huadong Zhong

    2015-01-01

    The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggr...

  20. Basalt mine-tailings as raw-materials for Portland clinker Rejeitos da mineração de basalto como matérias-primas para clínquer Portland

    OpenAIRE

    F. R. D. Andrade; M Pecchio; D. P Bendoraitis; T. J Montanheiro; Y Kihara

    2010-01-01

    Large volumes of waste materials are produced by crushing of basaltic rocks for aggregate production, which is widely used in regions that lack rocks of granitic or gneissic composition. Two types of waste materials are produced (a) quarry fines, which are in part used as fine aggregates in concrete and (b) vesicular basalt, a porous variety of basalt that is useless as aggregate. This paper presents a procedure to use basaltic mine-tailings as raw-mixtures for Portland cement by adjusting th...

  1. Hanford basalt flow mineralogy

    International Nuclear Information System (INIS)

    Mineralogy of the core samples from five core wells was examined in some detail. The primary mineralogy study included an optical examination of polished mounts, photomicrographs, chemical analyses of feldspars, pyroxenes, metallic oxides and microcrystalline groundmasses and determination from the chemical analyses of the varieties of feldspars, pyroxenes and metallic oxides. From the primary mineralogy data, a firm understanding of the average Hanford basalt flow primary mineralogy emerged. The average primary feldspar was a laboradorite, the average pyroxene was an augite and the average metallic oxide was a solid solution of ilmenite and magnetite. Secondary mineralization consisted of vug filling and joint coating, chiefly with a nontronite-beidellite clay, several zeolites, quartz, calcite, and opal. Specific flow units also were examined to determine the possibility of using the mineralogy to trace flows between core wells. These included units of the Pomona, the Umatilla and a high chromium flow just below the Huntzinger. In the Umatilla, or high barium flow, the compositional variation of the feldspars was unique in range. The pyroxenes in the Pomona were relatively highly zoned and accumulated chromium. The high chromium flow contained chromium spinels that graded in chromium content into simple magnetites very low in chromium content. A study of the statistical relationships of flow unit chemical constituents showed that flow unit constituents could be roughly correlated between wells. The probable cause of the correlation was on-going physical-chemical changes in the source magma

  2. Using of Local Limestone as Aggregate in Concrete Mixture

    Directory of Open Access Journals (Sweden)

    Dr.Muyasser M. Jomaa'h

    2012-03-01

    Full Text Available This research deals with the field investigations and construction properties for using limestone as a lightweight course aggregate in concrete mixture in stead of normal coarse aggregate. Concrete cubes samples have been prepared with dimensions of 150*150*150 mm according to ASTM. For these samples the normal coarse aggregate was replaced by 100% coarse crushed limestone. Three types of limestone which were used (Al-Sinea, Makhool and Himreen, it was found that the Al-Sinea type of limestone gave a good combination (fcu =32.11MPa without admixtures. The obtained results showed a suitable reduction in dead loads of structural elements and cost. Accordingly, the usage of limestone will improve the structural applications and concrete mix properties to attain economic viability. These above results make limestone as a good alternative of normal coarse aggregate

  3. Topological Coarse Shape Homotopy Groups

    OpenAIRE

    Ghanei, Fateme; Mirebrahimi, Hanieh; Mashayekhy, Behrooz; Nasri, Tayyebe

    2016-01-01

    Uchillo-Ibanez et al. introduced a topology on the sets of shape morphisms between arbitrary topological spaces in 1999. In this paper, applying a similar idea, we introduce a topology on the set of coarse shape morphisms $Sh^*(X,Y)$, for arbitrary topological spaces $X$ and $Y$. In particular, we can consider a topology on the coarse shape homotopy group of a topological space $(X,x)$, $Sh^*((S^k,*),(X,x))=\\check{\\pi}_k^{*}(X,x)$, which makes it a Hausdorff topological group. Moreover, we st...

  4. Deriving Coarse-Grained Charges from All-Atom Systems: An Analytic Solution.

    Science.gov (United States)

    McCullagh, Peter; Lake, Peter T; McCullagh, Martin

    2016-09-13

    An analytic method to assign optimal coarse-grained charges based on electrostatic potential matching is presented. This solution is the infinite size and density limit of grid-integration charge-fitting and is computationally more efficient by several orders of magnitude. The solution is also minimized with respect to coarse-grained positions which proves to be an extremely important step in reproducing the all-atom electrostatic potential. The joint optimal-charge optimal-position coarse-graining procedure is applied to a number of aggregating proteins using single-site per amino acid resolution. These models provide a good estimate of both the vacuum and Debye-Hückel screened all-atom electrostatic potentials in the vicinity and in the far-field of the protein. Additionally, these coarse-grained models are shown to approximate the all-atom dimerization electrostatic potential energy of 10 aggregating proteins with good accuracy.

  5. Recycled aggregates concrete: aggregate and mix properties

    Directory of Open Access Journals (Sweden)

    González-Fonteboa, B.

    2005-09-01

    Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

    Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

  6. Evaluation of Colemanite Waste as Aggregate Hot Mix Asphalt Concrete

    Directory of Open Access Journals (Sweden)

    Nihat MOROVA

    2015-09-01

    Full Text Available In this study usability of waste colemanite which is obtained after cutting block colemanite for giving proper shape to blocks as an aggregate in hot mix asphalt. For this aim asphalt concrete samples were prepared with four different aggregate groups and optimum bitumen content was determined. First of all only limestone was used as an aggregate. After that, only colemanite aggregate was used with same aggregate gradation. Then, the next step of the study, Marshall samples were produced by changing coarse and fine aggregate gradation as limestone and colemanite and Marshall test were conducted. When evaluated the results samples which produced with only limestone aggregate gave the maximum Marshall Stability value. When handled other mixture groups (Only colemanite, colemanite as coarse aggregate-limestone as fine aggregate, colemanite as fine aggregate-limestone as coarse aggregate all groups were verified specification limits. As a result, especially in areas where there is widespread colemanite waste, if transportation costs did not exceed the cost of limestone, colemanite stone waste could be used instead of limestone in asphalt concrete mixtures as fine aggregate

  7. Performance of Light-Weight Concrete with Plastic Aggregate

    Directory of Open Access Journals (Sweden)

    Anju Ramesan

    2015-08-01

    Full Text Available This study is intended to explore the suitability of recycled plastics (high density polyethylene as coarse aggregate in concrete by conducting various tests like workability by slump test, compressive strength of cube and cylinder, splitting tensile strength test of cylinder, flexural strength of R.C.C as well as P.CC. beams to determine the properties and behaviour in concrete. Effect of replacement of coarse aggregate with various percentages (0% to 40% of plastic aggregate on behaviour of concrete was experimentally investigated and the optimum replacement of coarse aggregate was found out. The results showed that the addition of plastic aggregate to the concrete mixture improved the properties of the resultant mix.

  8. Bubble Growth in Lunar Basalts

    Science.gov (United States)

    Zhang, Y.

    2009-05-01

    Although Moon is usually said to be volatile-"free", lunar basalts are often vesicular with mm-size bubbles. The vesicular nature of the lunar basalts suggests that they contained some initial gas concentration. A recent publication estimated volatile concentrations in lunar basalts (Saal et al. 2008). This report investigates bubble growth on Moon and compares with that on Earth. Under conditions relevant to lunar basalts, bubble growth in a finite melt shell (i.e., growth of multiple regularly-spaced bubbles) is calculated following Proussevitch and Sahagian (1998) and Liu and Zhang (2000). Initial H2O content of 700 ppm (Saal et al. 2008) or lower is used and the effect of other volatiles (such as carbon dioxide, halogens, and sulfur) is ignored. H2O solubility at low pressures (Liu et al. 2005), concentration-dependent diffusivity in basalt (Zhang and Stolper 1991), and lunar basalt viscosity (Murase and McBirney 1970) are used. Because lunar atmospheric pressure is essentially zero, the confining pressure on bubbles is completely supplied by the overlying magma. Due to low H2O content in lunar basaltic melt (700 ppm H2O corresponds to a saturation pressure of 75 kPa), H2O bubbles only grow in the upper 16 m of a basalt flow or lake. A depth of 20 mm corresponds to a confining pressure of 100 Pa. Hence, vesicular lunar rocks come from very shallow depth. Some findings from the modeling are as follows. (a) Due to low confining pressure as well as low viscosity, even though volatile concentration is very low, bubble growth rate is extremely high, much higher than typical bubble growth rates in terrestrial melts. Hence, mm-size bubbles in lunar basalts are not strange. (b) Because the pertinent pressures are so low, bubble pressure due to surface tension plays a main role in lunar bubble growth, contrary to terrestrial cases. (c) Time scale to reach equilibrium bubble size increases as the confining pressure increases. References: (1) Liu Y, Zhang YX (2000) Earth

  9. Strength of Concrete Containing Basalt Fibre

    Directory of Open Access Journals (Sweden)

    Parvez Imraan Ansari

    2015-04-01

    Full Text Available This paper presents the comparative study of effect of basalt fibre on compressive and split tensile strength of M40 grade concrete. The basalt fibre was mixed in concrete by (0.5%, 1%, and 1.5% of its total weight of cement in concrete. Results indicated that the strength increases with increase of basalt fibre content up to 1.0% beyond that there is a reduction in strength on increasing basalt fibre. The results show that the concrete specimen with 1.0% of basalt fibre gives better performance when it compared with 0.5%and 1.5% basalt fibre mix in concrete specimens.

  10. Coarse-graining complex dynamics

    DEFF Research Database (Denmark)

    Sibani, Paolo

    2013-01-01

    Continuous Time Random Walks (CTRW) are widely used to coarse-grain the evolution of systems jumping from a metastable sub-set of their configuration space, or trap, to another via rare intermittent events. The multi-scaled behavior typical of complex dynamics is provided by a fat-tailed distribu......Continuous Time Random Walks (CTRW) are widely used to coarse-grain the evolution of systems jumping from a metastable sub-set of their configuration space, or trap, to another via rare intermittent events. The multi-scaled behavior typical of complex dynamics is provided by a fat......-law and logarithmic relaxation behaviors ubiquitous in complex dynamics, together with the sub-diffusive time dependence of the Mean Square Displacement characteristic of single particles moving in a complex environment....

  11. Continuous coarse ash depressurization system

    Science.gov (United States)

    Liu, Guohai; Peng, Wan Wang; Vimalchand, Pannalal

    2012-11-13

    A system for depressurizing and cooling a high pressure, high temperature dense phase solids stream having coarse solid particles with entrained gas therein. In one aspect, the system has an apparatus for at least partially depressurizing and cooling the high pressure, high temperature dense phase solids stream having gas entrained therein and a pressure letdown device for further depressurization and separating cooled coarse solid particles from a portion of the entrained gas, resulting in a lower temperature, lower pressure outlet of solid particles for downstream processing or discharge to a storage silo for future use and/or disposal. There are no moving parts in the flow path of the solids stream in the system.

  12. Temperature dependence of basalt weathering

    Science.gov (United States)

    Li, Gaojun; Hartmann, Jens; Derry, Louis A.; West, A. Joshua; You, Chen-Feng; Long, Xiaoyong; Zhan, Tao; Li, Laifeng; Li, Gen; Qiu, Wenhong; Li, Tao; Liu, Lianwen; Chen, Yang; Ji, Junfeng; Zhao, Liang; Chen, Jun

    2016-06-01

    The homeostatic balance of Earth's long-term carbon cycle and the equable state of Earth's climate are maintained by negative feedbacks between the levels of atmospheric CO2 and the chemical weathering rate of silicate rocks. Though clearly demonstrated by well-controlled laboratory dissolution experiments, the temperature dependence of silicate weathering rates, hypothesized to play a central role in these weathering feedbacks, has been difficult to quantify clearly in natural settings at landscape scale. By compiling data from basaltic catchments worldwide and considering only inactive volcanic fields (IVFs), here we show that the rate of CO2 consumption associated with the weathering of basaltic rocks is strongly correlated with mean annual temperature (MAT) as predicted by chemical kinetics. Relations between temperature and CO2 consumption rate for active volcanic fields (AVFs) are complicated by other factors such as eruption age, hydrothermal activity, and hydrological complexities. On the basis of this updated data compilation we are not able to distinguish whether or not there is a significant runoff control on basalt weathering rates. Nonetheless, the simple temperature control as observed in this global dataset implies that basalt weathering could be an effective mechanism for Earth to modulate long-term carbon cycle perturbations.

  13. The effect of aggregate density on pavement performance of SMA-13 asphalt mixture

    Directory of Open Access Journals (Sweden)

    Qiao Yinping

    2016-05-01

    Full Text Available This paper chooses the top layer SMA-13 asphalt mixture material as the research object. Basalt was selected as pavement material, and modified SBS asphalt was used as a cementing material. Two basalt aggregates with different densities were used to carry out standard Marshall test in the laboratory.Aimed at the volume parameters of the asphalt mixture carry on anaiysis,and obtian the effect of aggregate density on pavement performance of SMA-13 asphalt mixture, which is that the density of aggregate has a significant effect on the void ratio, saturation, and the gap rate of the aggregate, thus affecting the pavement performance of the asphalt mixture

  14. Aggregate productivity and aggregate technology

    OpenAIRE

    Susanto Basu; John G. Fernald

    1997-01-01

    Aggregate productivity and aggregate technology are meaningful but distinct concepts. We show that a slightly-modified Solow productivity residual measures changes in economic welfare, even when productivity and technology differ because of distortions such as imperfect competition. We then present a general accounting framework that identifies several new non-technological gaps between productivity and technology, gaps reflecting imperfections and frictions in output and factor markets. Empi...

  15. INVESTIGATIONS ON RECYCLED CONCRETE AGGREGATE AND MSAND AS AGGREGATE REPLACEMENT IN CONCRETE

    OpenAIRE

    Sridhar, U; Karthick, B

    2015-01-01

    Gigantic numbers of building and destruction trashes are produced in emerging countries like India. The clearance of these trashes is serious problem because it requires huge space. The present work is to study the properties of concrete with replacement of 50% of nature sand by manufactured sand and coarse aggregates by different proportions with recycled concrete aggregates (RCA). A mix proportion for M20 grade concrete is derived with standards confirming to IS codes. RCA was p...

  16. Waste polyethylene terephthalate as an aggregate in concrete

    Directory of Open Access Journals (Sweden)

    Nabajyoti Saikia

    2013-04-01

    Full Text Available This paper reports the strength behaviour of concrete containing three types of recycled polyethylene terephthalate (PET aggregate. Results are also analysed to determine the PET-aggregate's effect on the relationship between the flexural and splitting tensile strengths and compressive strength and to know whether the relationships between compressive strength and other strength characteristics given in European design codes are applicable to concrete made with PET-aggregates. The compressive strength development of concrete containing all types of PET-aggregate behaves like in conventional concrete, though the incorporation of any type of PET-aggregate significantly lowers the compressive strength of the resulting concrete. The PET-aggregate incorporation improves the toughness behaviour of the resulting concrete. This behaviour is dependent on PET-aggregate's shape and is maximised for concrete containing coarse, flaky PET-aggregate. The splitting tensile and flexural strength characteristics are proportional to the loss in compressive strength of concrete containing plastic aggregates.

  17. Application of Base Force Element Method to Mesomechanics Analysis for Recycled Aggregate Concrete

    OpenAIRE

    Yijiang Peng; Yinghua Liu; Jiwei Pu; Lijuan Zhang

    2013-01-01

    The base force element method (BFEM) on potential energy principle is used to analyze recycled aggregate concrete (RAC) on mesolevel. The model of BFEM with triangular element is derived. The recycled aggregate concrete is taken as five-phase composites consisting of natural coarse aggregate, new mortar, new interfacial transition zone (ITZ), old mortar, and old ITZ on meso-level. The random aggregate model is used to simulate the mesostructure of recycled aggregate concrete. The mechanics pr...

  18. The Effects of Different Fine Recycled Concrete Aggregates on the Properties of Mortar

    OpenAIRE

    Cheng-Chih Fan; Ran Huang; Howard Hwang; Sao-Jeng Chao

    2015-01-01

    The practical use of recycled concrete aggregate produced by crushing concrete waste reduces the consumption of natural aggregate and the amount of concrete waste that ends up in landfills. This study investigated two methods used in the production of fine recycled concrete aggregate: (1) a method that produces fine as well as coarse aggregate, and (2) a method that produces only fine aggregate. Mortar specimens were tested using a variety of mix proportions to determine how the characteristi...

  19. Recycled Concrete as Aggregate for Structural Concrete Production

    OpenAIRE

    Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

    2010-01-01

    A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycle...

  20. HIGH TEMPERATURE PERFORMANCE OF SUSTAINABLE CONCRETE WITH RECYCLED CONCRETE AGGREGATES

    OpenAIRE

    Gales, John; Parker, Thomas; Green, Mark F.; Cree, Duncan; Bisby, Luke

    2014-01-01

    The substitution of conventional aggregates in concrete with recycled concrete aggregates (RCA) can act to lower environmental impact. Applications of concrete with RCA are limited because of a lack of research providing clear design guidance. Specifically, the performance in fire must be considered. To address this need, three different concrete mixes were assessed for performance at high temperature with the only variable being the proportion of coarse aggregate substituted with RCA. For ea...

  1. Recycled Concrete as Aggregate for Structural Concrete Production

    Directory of Open Access Journals (Sweden)

    Mirjana Malešev

    2010-04-01

    Full Text Available A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate. Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.

  2. Characterization of reference Umtanum and Cohassett basalt

    Energy Technology Data Exchange (ETDEWEB)

    Allen, C.C.; Johnston, R.G.; Strope, M.B.

    1985-02-01

    The Basalt Waste Isolation Project (BWIP) Materials Testing Group (MTG) provides large quantities of reference basalt for testing waste package materials under repository conditions, site sorption characteristics and other experimental purposes. This document describes the reference rock materials currently used in testing, namely entablature and colonnade basalt from the Umtanum and Cohassett flows. The data include sampling locations, bulk chemical composition, modal percentages of major phases, and the chemical and mineralogical compositions of these phases. 8 refs., 17 figs., 15 tabs.

  3. The Use of Basalt, Basalt Fibers and Modified Graphite for Nuclear Waste Repository - 12150

    Energy Technology Data Exchange (ETDEWEB)

    Gulik, V.I. [Institute for Nuclear Research, pr. Nauky 47, Kyiv, 03680 (Ukraine); Biland, A.B. [HHK Technologies, 3535 Wilcreast Dr., Houston TX 77042 (United States)

    2012-07-01

    New materials enhancing the isolation of radioactive waste and spent nuclear fuel are continuously being developed.. Our research suggests that basalt-based materials, including basalt roving chopped basalt fiber strands, basalt composite rebar and materials based on modified graphite, could be used for enhancing radioactive waste isolation during the storage and disposal phases and maintaining it during a significant portion of the post-closure phase. The basalt vitrification process of nuclear waste is a viable alternative to glass vitrification. Basalt roving, chopped basalt fiber strands and basalt composite rebars can significantly increase the strength and safety characteristics of nuclear waste and spent nuclear fuel storages. Materials based on MG are optimal waterproofing materials for nuclear waste containers. (authors)

  4. Construction aggregates

    Science.gov (United States)

    Nelson, T.I.; Bolen, W.P.

    2007-01-01

    Construction aggregates, primarily stone, sand and gravel, are recovered from widespread naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size and sold loose or combined with portland cement or asphaltic cement to make concrete products to build roads, houses, buildings, and other structures. Much smaller quantities are used in agriculture, cement manufacture, chemical and metallurgical processes, glass production and many other products.

  5. Subseafloor basalts as fungal habitats

    Science.gov (United States)

    Ivarsson, M.; Bengtson, S.

    2013-12-01

    The oceanic crust makes up the largest potential habitat for life on Earth, yet next to nothing is known about the abundance, diversity and ecology of its biosphere. Our understanding of the deep biosphere of subseafloor crust is, with a few exceptions, based on a fossil record. Surprisingly, a majority of the fossilized microorganisms have been interpreted or recently re-interpreted as remnants of fungi rather than prokaryotes. Even though this might be due to a bias in fossilization the presence of fungi in these settings can not be neglected. We have examined fossilized microorganisms in drilled basalt samples collected at the Emperor Seamounts in the Pacific Ocean. Synchrotron-radiation X-ray tomography microscopy (SRXTM) studies has revealed a complex morphology and internal structure that corresponds to characteristic fungal morphology. Chitin was detected in the fossilized hyphae, which is another strong argument in favour of a fungal interpretation. Chitin is absent in prokaryotes but a substantial constituent in fungal cell walls. The fungal colonies consist of both hyphae and yeast-like growth states as well as resting structures and possible fruit bodies, thus, the fungi exist in vital colonies in subseafloor basalts. The fungi have also been involved in extensive weathering of secondary mineralisations. In terrestrial environments fungi are known as an important geobiological agent that promotes mineral weathering and decomposition of organic matter, and they occur in vital symbiosis with other microorganisms. It is probable to assume that fungi would play a similar role in subseafloor basalts and have great impact on the ecology and on biogeochemical cycles in such environments.

  6. Origin of the Grande Ronde Basalts, Columbia River Basalt Group

    Science.gov (United States)

    Durand, S. R.; Sen, G.; Reidel, S. P.

    2005-12-01

    The Columbia River basalts are generally thought to have formed by plume melting. Takahashi et al. (1998) suggested that the near-aphyric Grande Ronde Basalts (GR), which comprise ~63% of the CRBG, are essentially primary melts formed by nearly complete fusion of eclogite source rock in the plume and that such melting took place ~2.0 GPa. Durand and Sen (2002) examined phenocrysts and whole rock analyses and concluded that all the basalts are non-primary and, more importantly, that they underwent significant "processing" in shallow crustal magma chambers which erased their higher pressure geochemical signal, thus casting doubt on the validity of the eclogitic plume melting model. Here we report the results of our efforts to simulate the higher pressure histories of GR basalts using COMAGMAT and MELTS software. Our intent was to evaluate (1) whether such melts could be derived from primary melts formed by partial melting of a peridotite source as an alternative to the eclogite model, or if bulk melting of eclogite is required; and (2) at what pressure such primary melts could have been in equilibrium with the mantle. We carried out both forward and inverse modeling. In the forward models we chose different starting melt compositions, all produced in laboratory experiments, from peridotite vs. eclogitic sources. Our starting melts were produced by 6-17% partial melting of the peridotite KLB-1 (Hirose and Kushiro, 1993) and 18-40% melting of eclogites (77SL-582; CRB72-31; Keshav et al., 2004; Takahashi et al., 1998) at 1-3.0 GPa. In a second model, our starting melt composition was the most primitive GR lava with 6.5 wt. % MgO. We extrapolated a linear regression through the GR data to 8 wt. % MgO. We then assumed that such a melt was only olivine-equilibrated, and incrementally added olivine while maintaining equilibrium between olivine and melt using a Kd of 0.3, until a melt in equilibrium with the mantle olivine (Fo89) was found. This composition was fractionated

  7. Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

    Directory of Open Access Journals (Sweden)

    Yuanchen Guo

    2015-01-01

    Full Text Available The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggregates is also measured through a statistical method, and the contact angle of different coarse aggregates and concrete is calculated according to the linear fitting relationship. Research shows that concrete strength is determined by aggregate strength. Aggregate wettability is not directly correlated with concrete strength, but wettability significantly affects concrete drying shrinkage. In all types’ pores, the greatest impacts on wettability are capillary pores and gel pores, especially for the pores of the size locating 2.5–50 nm and 50–100 nm two ranges.

  8. Experimental investigation of coarse particles-water mixture flow in horizontal and inclined pipes

    Directory of Open Access Journals (Sweden)

    Vlasák Pavel

    2014-09-01

    Full Text Available The effect of solid concentration and mixture velocity on the flow behaviour, pressure drops, and concentration distribution of coarse particle-water mixtures in horizontal, vertical, and inclined smooth stainless steel pipes of inner diameter D = 100 mm was experimentally investigated. Graded basalt pebbles were used as solid particles. The study revealed that the coarse-grained particle-water mixtures in the horizontal and inclined pipes were significantly stratified. The solid particles moved principally in a layer close to the pipe invert; however for higher and moderate flow velocities, particle saltation became the dominant mode of particle conveyance. Frictional pressure drops in the horizontal pipe were found to be markedly higher than in the vertical pipe, while the frictional pressure drops in the ascending pipe increased with inclination angle up to about 30°.

  9. Basaltic cannibalism at Thrihnukagigur volcano, Iceland

    Science.gov (United States)

    Hudak, M. R.; Feineman, M. D.; La Femina, P. C.; Geirsson, H.

    2014-12-01

    Magmatic assimilation of felsic continental crust is a well-documented, relatively common phenomenon. The extent to which basaltic crust is assimilated by magmas, on the other hand, is not well known. Basaltic cannibalism, or the wholesale incorporation of basaltic crustal material into a basaltic magma, is thought to be uncommon because basalt requires more energy than higher silica rocks to melt. Basaltic materials that are unconsolidated, poorly crystalline, or palagonitized may be more easily ingested than fully crystallized massive basalt, thus allowing basaltic cannibalism to occur. Thrihnukagigur volcano, SW Iceland, offers a unique exposure of a buried cinder cone within its evacuated conduit, 100 m below the main vent. The unconsolidated tephra is cross-cut by a NNE-trending dike, which runs across the ceiling of this cave to a vent that produced lava and tephra during the ~4 Ka fissure eruption. Preliminary petrographic and laser ablation inductively coupled mass spectrometry (LA-ICP-MS) analyses indicate that there are two populations of plagioclase present in the system - Population One is stubby (aspect ratio 2.1), subhedral to euhedral, and has much higher Ba/Sr ratios. Population One crystals are observed in the cinder cone, dike, and surface lavas, whereas Population Two crystals are observed only in the dike and surface lavas. This suggests that a magma crystallizing a single elongate population of plagioclase intruded the cinder cone and rapidly assimilated the tephra, incorporating the stubbier population of phenocrysts. This conceptual model for basaltic cannibalism is supported by field observations of large-scale erosion upward into the tephra, which is coated by magma flow-back indicating that magma was involved in the thermal etching. While the unique exposure at Thrihnukagigur makes it an exceptional place to investigate basaltic cannibalism, we suggest that it is not limited to this volcanic system. Rather it is a process that likely

  10. Hardness of basaltic glass-ceramics

    DEFF Research Database (Denmark)

    Jensen, Martin; Smedskjær, Morten Mattrup; Estrup, Maja;

    2009-01-01

    The dependence of the hardness of basaltic glass-ceramics on their degree of crystallisation has been explored by means of differential scanning calorimetry, optical microscopy, x-ray diffraction, and Vickers indentation. Different degrees of crystallisation in the basaltic glasses were achieved...

  11. Differentiation mechanism of frontal-arc basalt magmas

    Science.gov (United States)

    Kuritani, T.; Yoshida, T.; Kimura, J.; Hirahara, Y.; Takahashi, T.

    2012-04-01

    In a cooling magma chamber, magmatic differentiation can proceed both by fractionation of crystals from the main molten part of the magma body (homogeneous fractionation) and by mixing of the main magma with fractionated melt derived from low-temperature mush zones (boundary layer fractionation) (Jaupart and Tait, 1995, and references therein). The geochemical path caused by boundary layer fractionation can be fairly different from a path resulting from homogeneous fractionation (e.g., Langmuir, 1989). Therefore, it is important to understand the relative contributions of these fractionation mechanisms in magma chambers. Kuritani (2009) examined the relative roles of the two fractionation mechanisms in cooling basaltic magma chambers using a thermodynamics-based mass balance model. However, the basaltic magmas examined in the work were alkali-rich (Na2O+K2O > 4 wt.%). In this study, to explore differentiation mechanisms of frontal-arc basalt magmas that are volumetrically much more important than rear-arc alkali basalt magmas, the relative roles of the two fractionation mechanisms are examined for low-K tholetiitic basalt magma from Iwate Volcano, NE Japan arc, using the same mass balance model. First, the water content and the temperature of the Iwate magma were estimated. The Iwate lavas are moderately porphyritic, consisting of ~8 vol.% olivine and ~20 vol.% plagioclase phenocrysts. The olivine and plagioclase phenocrysts show significant compositional variations, and the Mg# of olivine phenocrysts (Mg#78-81) correlates positively with the An content of coexisting plagioclase phenocrysts (An85-92). The olivine phenocrysts with Mg# > ~82 do not form crystal aggregates with plagioclase. It is inferred from these observations that the phenocrysts with variable compositions were derived from a common magma with variable temperature in a magma chamber, and the plagioclase phenocrysts were all derived from mushy boundary layers along the walls of the magma chamber. By

  12. Coarse Grained Molecular Dynamics Simulations of Transmembrane Protein-Lipid Systems

    Directory of Open Access Journals (Sweden)

    Peter Spijker

    2010-06-01

    Full Text Available Many biological cellular processes occur at the micro- or millisecond time scale. With traditional all-atom molecular modeling techniques it is difficult to investigate the dynamics of long time scales or large systems, such as protein aggregation or activation. Coarse graining (CG can be used to reduce the number of degrees of freedom in such a system, and reduce the computational complexity. In this paper the first version of a coarse grained model for transmembrane proteins is presented. This model differs from other coarse grained protein models due to the introduction of a novel angle potential as well as a hydrogen bonding potential. These new potentials are used to stabilize the backbone. The model has been validated by investigating the adaptation of the hydrophobic mismatch induced by the insertion of WALP-peptides into a lipid membrane, showing that the first step in the adaptation is an increase in the membrane thickness, followed by a tilting of the peptide.

  13. NEW RSW & Wall Coarse Mixed Element Grid

    Data.gov (United States)

    National Aeronautics and Space Administration — This is the Coarse Mixed Element Grid for the RSW with a viscous wall at the root. This grid is for a node-based unstructured solver. Quad Surface Faces= 9728 Tria...

  14. NEW RSW & Wall Coarse Tet Only Grid

    Data.gov (United States)

    National Aeronautics and Space Administration — This is the RSW Coarse Tet Only grid with the root viscous tunnel wall. This grid is for a node-based unstructured solver. Quad Surface Faces= 0 Tria Surface Faces=...

  15. Quasiclassical Coarse Graining and Thermodynamic Entropy

    CERN Document Server

    Gell-Mann, Murray; Gell-Mann, Murray; Hartle, James

    2006-01-01

    Our everyday descriptions of the universe are highly coarse-grained, following only a tiny fraction of the variables necessary for a perfectly fine-grained description. Coarse graining in classical physics is made natural by our limited powers of observation and computation. But in the modern quantum mechanics of closed systems, some measure of coarse graining is inescapable because there are no non-trivial, probabilistic, fine-grained descriptions. This essay explores the consequences of that fact: Quantum theory allows for various coarse-grained descriptions some of which are mutually incompatible. For most purposes, however, we are interested in the small subset of ``quasiclassical descriptions'' defined by ranges of values of averages over small volumes of densities of conserved quantities such as energy and momentum and approximately conserved quantities such as baryon number. The near-conservation of these quasiclassical quantities results in approximate decoherence, predictability, and local equilibriu...

  16. Coarse Thinking and Pricing a Financial Option

    OpenAIRE

    Siddiqi, Hammad

    2009-01-01

    Mullainathan et al [Quarterly Journal of Economics, May 2008] present a formalization of the concept of coarse thinking in the context of a model of persuasion. The essential idea behind coarse thinking is that people put situations into categories and the values assigned to attributes in a given situation are affected by the values of corresponding attributes in other co-categorized situations. We derive a new option pricing formula based on the assumption that the market consists of coars...

  17. Coarse graining lessons from simple examples

    CERN Document Server

    Akritas, P; Yarevsky, E

    2001-01-01

    We assess Coarse Graining by studying different partitions of the phase space of the Baker transformation and the periodic torus automorphisms. It turns out that the shape of autocorrelation functions for the Baker transformation is more or less reproduced. However, for certain partitions the decay rates turn out to be irrelevant, even decay may stop in a finite time. For the periodic torus automorphisms, Coarse Graining introduces artificial dumping.

  18. Effect of Chipped Rubber Aggregates on Performance of Concrete

    OpenAIRE

    Sunil N. Shah; Pradip D. Jadhao; S. M. Dumne

    2014-01-01

    Due to rapid growth in automobile industry, use of tyre increases day to day and there is no reuse of the same to decrease the environmental pollution. The decomposition and disposing of waste tyre rubber is harmful to environment. This research reflects the reuse of waste tyre rubber into concrete after observing their properties. In that experimental work chipped rubber aggregates replaced to the natural coarse aggregates by varying percentage of 3, 6, 9 and 12 with comparison of 0% repl...

  19. Durability Indicators in High Absorption Recycled Aggregate Concrete

    OpenAIRE

    Jiménez, Luis F.; Moreno, Eric I.

    2015-01-01

    The use of recycled aggregates in structural concrete production has the inconvenience of increasing the fluid transport properties, such as porosity, sorptivity, and permeability, which reduces the resistance against penetration of environmental loads such as carbon dioxide and chloride ion. In this paper, behavior of ten concrete mixtures with different percentages of coarse aggregate replacement was studied. The recycled material was recovered by crushing of concrete rubble and had high ab...

  20. Properties of high-workability concrete with recycled concrete aggregate

    OpenAIRE

    Safiuddin; Ubagaram Johnson Alengaram; Abdus Salam; Mohd Zamin Jumaat; Fahrol Fadhli Jaafar; Hawa Binti Saad

    2011-01-01

    This study presents the effects of recycled concrete aggregate (RCA) on the key fresh and hardened properties of concrete. RCA was used to produce high-workability concrete substituting 0-100% natural coarse aggregate (NCA) by weight. The slump and slump flow of fresh concretes were determined to ensure high workability. In addition, the compressive, flexural and splitting tensile strengths, modulus of elasticity, and permeable voids of hardened concretes were determined. The test results rev...

  1. Coarse-Grained Model for Colloidal Protein Interactions, B22, and Protein Cluster Formation

    OpenAIRE

    Blanco, Marco A.; Sahin, Eric; Robinson, Anne S.; Roberts, Christopher J.

    2013-01-01

    Reversible protein cluster formation is an important initial step in the processes of native and non-native protein aggregation, but involves relatively long time and length scales for detailed atomistic simulations and extensive mapping of free energy landscapes. A coarse-grained (CG) model is presented to semi-quantitatively characterize the thermodynamics and key configurations involved in the landscape for protein oligomerization, as well as experimental measures of interactions such as t...

  2. Asbestos Tailings as Aggregates for Asphalt Mixture

    Institute of Scientific and Technical Information of China (English)

    LIU Xinoming; XU Linrong

    2011-01-01

    To use many asbestos tailings collected in Ya-Lu highway, and to explore the feasibility of using asbestos tailings as aggregates in common asphalt mixtures, and properties of some asphalt mixtures were evaluated as well. X-ray diffraction (XRD), X-ray fluorescent (XRF), and atomic absorption spectrophotometry (AAS) were employed to determine the solid waste content of copper, zinc, lead, and cadmium. Volume properties and pavement performances of AC-25 asphalt mixture with asbestos tailings were also evaluated compared with those with basalt as aggregates.XRD and XRF measurement results infer that asbestos tailing is an excellent road material. Volume properties of AC-25 asphalt mixture with asbestos tailings satisfied the related specifications. No heavy metals and toxic pollution were detected in AAS test and the value of pH test is 8.23, which is help to the adhesion with asphalt in the asphalt concrete. When compared with basalt, high temperature property and the resistance to low temperature cracking of AC-25 asphalt mixture was improved by using asbestos tailings as aggregates. In-service AC-25 asphalt pavement with asbestos tailings also presented excellent performance and British Pendulum Number (BPN) coefficient of surface.

  3. Orthopyroxene fractionation in the Grande Ronde Basalt--Columbia River Basalt group

    International Nuclear Information System (INIS)

    Six orthopyroxenes were microprobed; five orthopyroxenes were from the Grande Ronde Basalt, and one was from the Buford flow of the Saddle Mountains Basalt. The orthopyroxenes are primarily bronzite in composition, but some analyses show that hypersthene is present. The reaction rims of all analyzed orthopyroxene crystals are pigeonite, while the groundmass pyroxene is both augite and pigeonite. Preliminary results from the least-squares linear modeling of the Grande Ronde Basalt indicate orthopyroxene is a necessary phase for mass balancing between flow compositions. Three models were tried in order to determine if selected mineral phases could be used to model the chemical compositions of the flows. These models suggest that orthopyroxene and plagioclase are phases common to the Grande Ronde Basalt. The similarity of orthopyroxene and plagioclase occurrences suggests that they are important intratelluric phases of the Grande Ronde Basalt which reacted out when the basaltic liquids were erupted at the surface

  4. An analysis of Apollo lunar soil samples 12070,889, 12030,187, and 12070,891: Basaltic diversity at the Apollo 12 landing site and implications for classification of small-sized lunar samples

    Science.gov (United States)

    Alexander, Louise; Snape, Joshua F.; Joy, Katherine H.; Downes, Hilary; Crawford, Ian A.

    2016-09-01

    Lunar mare basalts provide insights into the compositional diversity of the Moon's interior. Basalt fragments from the lunar regolith can potentially sample lava flows from regions of the Moon not previously visited, thus, increasing our understanding of lunar geological evolution. As part of a study of basaltic diversity at the Apollo 12 landing site, detailed petrological and geochemical data are provided here for 13 basaltic chips. In addition to bulk chemistry, we have analyzed the major, minor, and trace element chemistry of mineral phases which highlight differences between basalt groups. Where samples contain olivine, the equilibrium parent melt magnesium number (Mg#; atomic Mg/[Mg + Fe]) can be calculated to estimate parent melt composition. Ilmenite and plagioclase chemistry can also determine differences between basalt groups. We conclude that samples of approximately 1-2 mm in size can be categorized provided that appropriate mineral phases (olivine, plagioclase, and ilmenite) are present. Where samples are fine-grained (grain size basalts. Of the fragments analyzed here, three are found to belong to each of the previously identified olivine and ilmenite basalt suites, four to the pigeonite basalt suite, one is an olivine cumulate, and two could not be categorized because of their coarse grain sizes and lack of appropriate mineral phases. Our approach introduces methods that can be used to investigate small sample sizes (i.e., fines) from future sample return missions to investigate lava flow diversity and petrological significance.

  5. Influence of granitic aggregates from Northeast Brazil on the alkali-aggregate reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gomes Neto, David de Paiva; Santana, Rodrigo Soares de; Barreto, Ledjane Silva, E-mail: pvgomes@uol.com.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Ciencias dos Materiais e Engenharia; Conceicao, Herbert; Lisboa, Vinicios Anselmo Carvalho [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Geologia

    2014-08-15

    The alkali-aggregate reaction (AAR) in concrete structures is a problem that has concerned engineers and researchers for decades. This reaction occurs when silicates in the aggregates react with the alkalis, forming an expanded gel that can cause cracks in the concrete and reduce its lifespan. The aim of this study was to characterize three coarse granitic aggregates employed in concrete production in northeastern Brazil, correlating petrographic analysis with the kinetics of silica dissolution and the evolution of expansions in mortar bars, assisted by SEM/EDS, XRD, and EDX. The presence of grains showing recrystallization into individual microcrystalline quartz subgrains was associated with faster dissolution of silica and greater expansion in mortar bars. Aggregates showing substantial deformation, such as stretched grains of quartz with strong undulatory extinction, experienced slower dissolution, with reaction and expansion occurring over longer periods that could not be detected using accelerated tests with mortar bars. (author)

  6. Basaltic Soil of Gale Crater: Crystalline Component Compared to Martian Basalts and Meteorites

    Science.gov (United States)

    Treiman, A. H.; Bish, D. L.; Ming, D. W.; Morris, R. V.; Schmidt, M.; Downs, R. T.; Stolper, E. M.; Blake, D. F.; Vaniman, D. T.; Achilles, C. N.; Chipera, S. J.; Bristow, T. F.; Crisp, J. A.; Farmer, J. A.; Morookian, J. M.; Morrison, S. M.; Rampe, E. B.; Sarrazin, P.; Yen, A. S.; Anderosn, R. C.; DesMarais, D. J.; Spanovich, N.

    2013-01-01

    A significant portion of the soil of the Rocknest dune is crystalline and is consistent with derivation from unweathered basalt. Minerals and their compositions are identified by X-ray diffraction (XRD) data from the CheMin instrument on MSL Curiosity. Basalt minerals in the soil include plagioclase, olivine, low- and high-calcium pyroxenes, magnetite, ilmenite, and quartz. The only minerals unlikely to have formed in an unaltered basalt are hematite and anhydrite. The mineral proportions and compositions of the Rocknest soil are nearly identical to those of the Adirondack-class basalts of Gusev Crater, Mars, inferred from their bulk composition as analyzed by the MER Spirit rover.

  7. Noble Gases and Halogens in Icelandic Basalts

    OpenAIRE

    Weston, Bridget

    2013-01-01

    Noble gas and halogen data from a suite of Icelandic samples are presented. Iceland combines hotspot volcanism, a spreading ridge and abundant subglacially erupted samples. This combination allows for samples that erupted under high enough pressures to retain a measurable mantle volatile content, and also display signatures representing interaction between ocean island basalt (OIB) and mid-ocean ridge basalt (MORB) mantle sources.Erupted samples used to determine the mantle’s halogen and nobl...

  8. Hydrothermal evolution of repository groundwaters in basalt

    International Nuclear Information System (INIS)

    Groundwaters in the near field of a radioactive waste repository in basalt will change their chemical composition in response to reactions with the basalt. These reactions will be promoted by the heat generated by the decaying waste. It is important to predict both the rate and the extent of these reactions, and the secondary minerals produced, because the alteration process controls the chemical environment affecting the corrosion of the canister, the solubility and complexation of migrating radionuclides, the reactivity of the alteration products to radionuclides sorption, and the porosity and permeability of the host rock. A comprehensive review of the literature leads to the preliminary finding that hydrothermally altering basalts in geothermal regions such as Iceland lead to a secondary mineralogy and groundwater composition similar to that expected to surround a repository. Furthermore, laboratory experiments replicating the alteration conditions approximate those observed in the field and expected in a repository. Preliminary estimates were made of the rate of hydration and devitrification of basaltic glass and the zero-order dissolution rate of basaltic materials. The rates were compared with those for rhyolitic glasses and silicate minerals. Preliminary calculations made of mixed process alteration kinetics, involving pore diffusion and surface reaction suggest that at temperatures greater than 1500C, alteration proceeds so rapidly as to become pervasive in normally fractured basalt exposed to higher temperatures in the field. 70 references

  9. Fractal dimension and mechanism of aggregation of apple juice particles.

    Science.gov (United States)

    Benítez, E I; Lozano, J E; Genovese, D B

    2010-04-01

    Turbidity of freshly squeezed apple juice is produced by a polydisperse suspension of particles coming from the cellular tissue. After precipitation of coarse particles by gravity, only fine-colloidal particles remain in suspension. Aggregation of colloidal particles leads to the formation of fractal structures. The fractal dimension is a measure of the internal density of these aggregates and depends on their mechanism of aggregation. Digitized images of primary particles and aggregates of depectinized, diafiltered cloudy apple juice were obtained by scanning electron microscopy (SEM). Average radius of the primary particles was found to be a = 40 ± 11 nm. Maximum radius of the aggregates, R(L), ranged between 250 and 7750 nm. Fractal dimension of the aggregates was determined by analyzing SEM images with the variogram method, obtaining an average value of D(f) = 2.3 ± 0.1. This value is typical of aggregates formed by rapid flocculation or diffusion limited aggregation. Diafiltration process was found to reduce the average size and polydispersity of the aggregates, determined by photon correlation spectroscopy. Average gyration radius of the aggregates before juice diafiltration was found to be R(g) = 629 ± 87 nm. Average number of primary particles per aggregate was calculated to be N = 1174. PMID:21339133

  10. Modelling airborne dispersion of coarse particulate material

    International Nuclear Information System (INIS)

    Methods of modelling the airborne dispersion and deposition of coarse particulates are presented, with the emphasis on the heavy particles identified as possible constituents of releases from damaged AGR fuel. The first part of this report establishes the physical characteristics of the irradiated particulate in airborne emissions from AGR stations. The second part is less specific and describes procedures for extending current dispersion/deposition models to incorporate a coarse particulate component: the adjustment to plume spread parameters, dispersion from elevated sources and dispersion in conjunction with building effects and plume rise. (author)

  11. Influence of pH and sequence in peptide aggregation via molecular simulation

    International Nuclear Information System (INIS)

    We employ a recently developed coarse-grained model for peptides and proteins where the effect of pH is automatically included. We explore the effect of pH in the aggregation process of the amyloidogenic peptide KTVIIE and two related sequences, using three different pH environments. Simulations using large systems (24 peptides chains per box) allow us to describe the formation of realistic peptide aggregates. We evaluate the thermodynamic and kinetic implications of changes in sequence and pH upon peptide aggregation, and we discuss how a minimalistic coarse-grained model can account for these details

  12. Influence of mineral aggregates on the rheological properties of concrete mixture

    Science.gov (United States)

    Klovas, A.; Daukšys, M.

    2015-04-01

    The aim of this research was to determine how the change of concrete mixture constituents: concentration of fine and coarse aggregate as well as the amount of fine particles, not exceeding 0.25 mm, influence concrete mixture's rheological properties. Firstly, inner- concentration of fine aggregate (sand, fraction of 0/1 and 0/4) was changed. Secondly, coarse aggregate (gravel, fraction of 4/16) concentration was changed and finally, the amount of fine particles was changed. Results have shown that with the increase of sand (fraction of 0/1) quantity, the plastic viscosity also increased. On the other hand, yield stress, at the beginning decreased, but eventually - increased. The increase of coarse aggregate quantity acted differently: plastic viscosity and yield stress decreased. Finally, the increase of fine particles quantity decreased the plastic viscosity as well as yield stress of concrete mixture.

  13. Properties of Recycled Aggregate Concrete Reinforced with Polypropylene Fibre

    Directory of Open Access Journals (Sweden)

    Wan Mohammad Wan Nur Syazwani

    2016-01-01

    Full Text Available This research work is aimed to investigate how the addition of various proportion of polypropylene fibre affects the mechanical strength and permeability characteristics of recycled aggregate concrete (RAC which has been produced with treated coarse recycled concrete aggregate (RCA. Further research on RAC properties and their applications is of great importance as the scarcity of virgin aggregate sources in close proximity to major urban centers is becoming a worldwide problem. In this study, the hardened RAC properties at the curing age of 7 and 28 days such as compressive strength, flexural strength, ultrasonic pulse velocity (UPV, water absorption and total porosity were evaluated and compare with control specimens. Experimental result indicates that although the inclusion of the treated coarse RCA can enhance the mechanical strength and permeability properties of RAC, Further modification by addition of polypropylene fibre can optimize the results.

  14. Effect of Chipped Rubber Aggregates on Performance of Concrete

    Directory of Open Access Journals (Sweden)

    Sunil N. Shah

    2014-12-01

    Full Text Available Due to rapid growth in automobile industry, use of tyre increases day to day and there is no reuse of the same to decrease the environmental pollution. The decomposition and disposing of waste tyre rubber is harmful to environment. This research reflects the reuse of waste tyre rubber into concrete after observing their properties. In that experimental work chipped rubber aggregates replaced to the natural coarse aggregates by varying percentage of 3, 6, 9 and 12 with comparison of 0% replacement. Silica fume is replaced in 10% with cement for improving the bond properties between cement paste and rubber. In evaluation, test has been carried out to determine the properties of concrete such as workability, unit weight, flexural strength and split tensile strength. The workability of fresh concrete is observed with the help of compaction factor test. From the test of compaction factor, workability is decrease with increasing percentage of chipped rubber. The specific gravity of chipped rubber aggregates is lower as compared to natural aggregates therefore decrease the unit weight of rubber mix concrete. Increasing chipped rubber aggregates as partial replacement into concrete reduces compressive strength. So these can use in non-primary structural applications of medium to low strength requirements. The overall results of study show that it is possible to use recycled rubber tyre aggregates in concrete construction as partial replacement to natural coarse aggregates.

  15. Complex Formation History of Highly Evolved Basaltic Shergottite, Zagami

    Science.gov (United States)

    Niihara, T.; Misawa, K.; Mikouchi, T.; Nyquist, L. E.; Park, J.; Hirata, D.

    2012-01-01

    Zagami, a basaltic shergottite, contains several kinds of lithologies such as Normal Zagami consisting of Fine-grained (FG) and Coarse-grained (CG), Dark Mottled lithology (DML), and Olivine-rich late-stage melt pocket (DN). Treiman and Sutton concluded that Zagami (Normal Zagami) is a fractional crystallization product from a single magma. It has been suggested that there were two igneous stages (deep magma chamber and shallow magma chamber or surface lava flow) on the basis of chemical zoning features of pyroxenes which have homogeneous Mg-rich cores and FeO, CaO zoning at the rims. Nyquist et al. reported that FG has a different initial Sr isotopic ratio than CG and DML, and suggested the possibility of magma mixing on Mars. Here we report new results of petrology and mineralogy for DML and the Olivine-rich lithology (we do not use DN here), the most evolved lithology in this rock, to understand the relationship among lithologies and reveal Zagami s formation history

  16. Radionuclide reactions with groundwater and basalts from Columbia River basalt formations

    International Nuclear Information System (INIS)

    Chemical reactions of radionuclides with geologic materials found in Columbia River basalt formations were studied. The objective was to determine the ability of these formations to retard radionuclide migration from a radioactive waste repository located in deep basalt. Reactions that can influence migration are precipitation, ion-exchange, complexation, and oxidation-reduction. These reactions were studied by measuring the effects of groundwater composition and redox potential (Eh) on radionuclide sorption on fresh basalt surfaces, a naturally altered basalt, and a sample of secondary minerals associated with a Columbia River basalt flow. In addition, radionuclide sorption isotherms were measured for these materials and reaction kinetics were determined. The radionuclides studied were 137Cs, 85Sr, 75Se, /sup 95m/Tc, 237Np, 241Am, 226Ra and 237Pu. The Freundlich equation accurately describes the isotherms when precipitation of radionuclides does not occur. In general, sorption increased in the order: basalt < altered basalt < secondary minerals. This increase in sorption corresponds to increasing surface area and cation exchange capacity. The Eh of the system had a large effect on technetium, plutonium, and neptunium sorption. Technetium(VII), Pu(VI), and Np(V) are reduced to Tc(IV), Pu(IV), and Np(IV), respectively, under Eh conditions expected in deep basalt formations. The kinetics of radionuclide sorption and basalt-groundwater reactions were observed over a period of 18 weeks. Most sorption reactions stabilized after about four weeks. Groundwater composition changed the least in contact with altered basalt. Contact with secondary minerals greatly increased Ca, K, and Mg concentrations in the groundwater

  17. 粗集料的表面微观纹理的激光测量方法及分形性质研究%Research on Measurement of Surface Micro-texture of Aggregate Using Laser and Its Fractal Character

    Institute of Scientific and Technical Information of China (English)

    张肖宁; 孙杨勇

    2011-01-01

    研制了一种采用激光三角测量技术的微距测量系统,对路面常用的花岗岩、玄武岩等粗集料的表面微观纹理进行测量,并分析了系统各种误差等干扰因素.利用MATLAB平台,采用盒子计数法对各种表面曲线及其所对应的原始数据进行分析,得出表面纹理的分形维数.测量分析系统总体抗干扰能力较强,满足粗集料微观测量要求,系统总体可靠、可行.对比研究结果表明,粗集料表面微观纹理分维数越大则其粗糙程度越复杂,越有利于提高路面抗滑性能,所选样品的玄武岩,花岗岩和卵石的表面微观纹理分维数依次减小且分维数有明显差异,符合实际应用情况,因此本测量分析方法为沥青面层石料的优选提供了新的方法和指标.%A micro-distance measurement system was developed using laser triangulation technique, the surface micro-texture of granite, basalt and other coarse aggregates commonly used on the road was measured,and the system errors were analyzed. Using MATLAB platform, the curves and their original data of various surfaces were analysised by box-counting method, and the fractal dimension of surface texture was derived.The overall anti-interference ability of the measurement system is strong and meets the requirements of coarse aggregate micro-measurement, and the overall system is reliable and feasible. Comparative results show that (1) the larger the fractal dimension of surface micro-texture of coarse aggregate, the more complex its roughness, and more help to improve road skid resistance; (2) the fractal dimensions of surface microtexture of the selected samples of basalt, granite and pebble decrease in order and the fractal dimensions are significantly different, which in line with the actual application. Therefore, this measurement method provides a new approach and indicators for the stone preferred for asphalt surface.

  18. Influence of mixed recycled aggregate on the physical e mechanical properties of recycled concrete

    OpenAIRE

    Medina Martínez, César; Zhu, Wenzhong; Howind, Torsten; Sánchez de Rojas, María Isabel; Frías Rojas, Moisés

    2014-01-01

    This article discusses the findings of a feasibility study on the partial replacement of natural coarse aggregate with a poor quality recycled aggregate from construction and demolition waste in the manufacture of concrete of 30 MPa strength grade. The mixed recycled aggregate used had a high asphalt and floating material content. Workability, density, compressive and tensile strength, water absorption and sorptivity were studied in a series of concretes containing 25 or 50% of th...

  19. Effect of Fractal Dimension of Fine Aggregates on the Concrete Chloride Resistance

    OpenAIRE

    Xue, Wen; J. Chen

    2016-01-01

    The relationship between fractal dimension of fine aggregates and the chloride resistance of concrete was investigated in this study. Both concrete and mortar specimens were cast. Concrete specimens were in the same mix design as the mortar specimens except for the coarse aggregates. The specimens were divided into different groups based on the gradation of the fine aggregates. The chloride resistances of concrete specimens were tested by using the rapid chloride migration method. The results...

  20. Assessment Of Blending Local And Imported Aggregates On Properties Of Their Asphalt Concrete Mixtures

    OpenAIRE

    Noureldin, Magdy S.

    1995-01-01

    Environmental conditions in the State of Qatar together with lack of good-quality aggregates seem to severely reduce the service lives of constructed pavements. The current practice of road construction agencies in Qatar is to utilize Marshall method of mix design to arrive at the best combination of aggregates, commonly crushed local limestone or imported Gabbro as coarse and fine aggregates and a mineral filler, and the 60/70 pen. grade bitumen. Little effort was undertaken to investigate ...

  1. Can we identify source lithology of basalt?

    Science.gov (United States)

    Yang, Zong-Feng; Zhou, Jun-Hong

    2013-01-01

    The nature of source rocks of basaltic magmas plays a fundamental role in understanding the composition, structure and evolution of the solid earth. However, identification of source lithology of basalts remains uncertainty. Using a parameterization of multi-decadal melting experiments on a variety of peridotite and pyroxenite, we show here that a parameter called FC3MS value (FeO/CaO-3*MgO/SiO2, all in wt%) can identify most pyroxenite-derived basalts. The continental oceanic island basalt-like volcanic rocks (MgO>7.5%) (C-OIB) in eastern China and Mongolia are too high in the FC3MS value to be derived from peridotite source. The majority of the C-OIB in phase diagrams are equilibrium with garnet and clinopyroxene, indicating that garnet pyroxenite is the dominant source lithology. Our results demonstrate that many reputed evolved low magnesian C-OIBs in fact represent primary pyroxenite melts, suggesting that many previous geological and petrological interpretations of basalts based on the single peridotite model need to be reconsidered.

  2. Feasibility Study of Applying Recycled Aggregate from Building Debris in Concrete

    Institute of Scientific and Technical Information of China (English)

    PENG Yuzhu

    2011-01-01

    Coarse and fine aggregate constitutes an average of approximately 55% to 80% of the total volume of concrete materials.Concrete remains the most commonly-used building material worldwide.As a result,the massive use of aggregate will have a direct impact on the earth's natural resources if an appropriate replacement material is not found,violating the spirit of sustainable development.This study makes a preliminary examination of using coarse and fine aggregate produced from discarded construction materials in concrete.Results indicate that the compressive strength of densified mixture concrete at 28 days can reach 56.88MPa( recycled materials used as coarse aggregate,and natural sand used as fine aggregate)and 53.33 MPa (recycled materials used as both coarse and fine aggregate).While this type of material is not yet fully understood,further research into this area should enable feasible applications in concrete.However,unsuitable mixtures have serious impact on the durability and overall economy of concrete.Pending further research on suitable mixture designs,a complete application of recycled aggregate in concrete can be expected.

  3. Interplay between the hydrophobic effect and dipole interactions in peptide aggregation at interfaces.

    Science.gov (United States)

    Ganesan, Sai J; Matysiak, Silvina

    2016-01-28

    Protein misfolding is an intrinsic property of polypeptides, and misfolded conformations have a propensity to aggregate. In the past decade, the development of various coarse-grained models for proteins has provided key insights into the driving forces in folding and aggregation. We recently developed a low resolution Water Explicit Polarizable PROtein coarse-grained Model (WEPPROM) by adding oppositely charged dummy particles inside protein backbone beads. With this model, we were able to achieve significant α/β secondary structure content, without any added bias. We now extend the model to study peptide aggregation at hydrophobic-hydrophilic interfaces and draw comparisons to aggregation in explicit water solvent. Elastin-like octapeptides (GV)4 are used as a model system for this study. A condensation-ordering mechanism of aggregation is observed in water. Our results suggest that backbone interpeptide dipolar interactions, not hydrophobicity, plays a more significant role in fibril-like peptide aggregation. We observe a cooperative effect in hydrogen bonding or dipolar interactions, with an increase in aggregate size in water and at interfaces. Based on this cooperative effect, we provide a potential explanation for the observed nucleus size in peptide aggregation pathways. The presence of a hydrophobic-hydrophilic interface increases both (a) order of aggregates formed, and (b) rate of the aggregation process. Without dipolar particles, peptide aggregation is not observed at the hydrophilic-hydrophobic interface. Thus, the presence of dipoles, not hydrophobicity, plays a key role in aggregation observed at hydrophobic interfaces. PMID:26698374

  4. Study of crystallization of a basalt glass

    International Nuclear Information System (INIS)

    Basalt vitreous ceramics posses industrial importance by presenting high mechanical resistance to the abrasion. It was studied the obtention and the crystallization of a glass obtained from a basalt of Campinas, Sao Paulo, Brazil, aiming to develop a material with great abrasive resistance. Fusions were made at 1400 deg Celsius in electrical oven and in alumina crucible, of fine residues of basalt mining. The obtained glass was treated in a crystallization temperature of 880 deg Celsius, determined by DSC, by various time of treatment. The present main crystalline phases, detected by XRD, were the magnesium-ferrite (MgFe2O4) and the diopsid Ca(Mg,Fe,Al)(Si,Al)2O6. Analysing the density by the Archimedes methodology and the DRX it was possible to follow the crystallization kinetic up.

  5. Pressure grouting of fractured basalt flows

    International Nuclear Information System (INIS)

    This report describes a field trial of pressure grouting in basalt and presents the results of subsequent coring and permeability measurements. The trial shows that hydraulic conductivity of fractured basalt bedrock can be significantly reduced by pressure injection of cementitious materials. The effectiveness of the pressure grout procedure was evaluated by measuring the change in the hydraulic conductivity of the bedrock. The extent of grout penetration was determined by analyzing postgrout injection drilling chips for the presence of a tracer in the grout and also by examining cores of the treated basalt. Downhole radar mapping indicated major lava flow patterns and follow water movement during a surface infiltration test. A site called Box Canyon, which is northwest of the Idaho National Engineering Laboratory (INEL), was chosen for the study because its surface outcrop geology is similar to the underlying bedrock fracture system at the INEL's Radioactive Waste Management Complex (RWMC)

  6. Acoustic emission monitoring of recycled aggregate concrete under bending

    Science.gov (United States)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.

  7. CO2 sequestration in basalts: laboratory measurements

    Science.gov (United States)

    Otheim, L. T.; Adam, L.; van Wijk, K.; McLing, T. L.; Podgorney, R. K.

    2010-12-01

    Geologic sequestration of CO2 is proposed as the only promising large-scale method to help reduce CO2 gas emission by its capture at large point sources and subsequent long-term storage in deep geologic formations. Reliable and cost-effective monitoring will be important aspect of ensuring geological sequestration is a safe, effective, and acceptable method for CO2 emissions mitigation. Once CO2 injection starts, seismic methods can be used to monitor the migration of the carbon dioxide plume. To calibrate changes in rock properties from field observations, we propose to first analyze changes in elastic properties on basalt cores. Carbon dioxide sequestration in basalt rocks results in fluid substitution and mixing of CO2 with water and rock mineralizations. Carbon dioxide sequestration in mafic rocks creates reactions such as Mg2SiO 4 + CaMgSi2O 6 + 4CO2 = Mg 3Ca(CO 3) 4 + 3SiO2 whereby primary silicate minerals within the basalt react with carbonic acid laden water to creating secondary carbonate minerals and silicates. Using time-lapse laboratory scale experiments, such as laser generated ultrasonic wave propagation; it is possible to observe small changes in the physical properties of a rock. We will show velocity and modulus measurements on three basalt core samples for different saturation. The ultimate goal of the project is to track seismic changes due to fluid substitution and mineralization. The porosity of our basalts ranges from 8% to 12%, and the P-wave velocity increases by 20% to 40% from dry to water saturated conditions. Petrographic analysis (CT-scans, thin sections, XRF, XRf) will aid in the characterization of the mineral structure in these basalts and its correlation to seismic properties changes resulting from fluid substitution and mineralization.

  8. Unconstrained Structure Formation in Coarse-Grained Protein Simulations

    Science.gov (United States)

    Bereau, Tristan

    The ability of proteins to fold into well-defined structures forms the basis of a wide variety of biochemical functions in and out of the cell membrane. Many of these processes, however, operate at time- and length-scales that are currently unattainable by all-atom computer simulations. To cope with this difficulty, increasingly more accurate and sophisticated coarse-grained models are currently being developed. In the present thesis, we introduce a solvent-free coarse-grained model for proteins. Proteins are modeled by four beads per amino acid, providing enough backbone resolution to allow for accurate sampling of local conformations. It relies on simple interactions that emphasize structure, such as hydrogen bonds and hydrophobicity. Realistic alpha/beta content is achieved by including an effective nearest-neighbor dipolar interaction. Parameters are tuned to reproduce both local conformations and tertiary structures. By studying both helical and extended conformations we make sure the force field is not biased towards any particular secondary structure. Without any further adjustments or bias a realistic oligopeptide aggregation scenario is observed. The model is subsequently applied to various biophysical problems: (i) kinetics of folding of two model peptides, (ii) large-scale amyloid-beta oligomerization, and (iii) protein folding cooperativity. The last topic---defined by the nature of the finite-size thermodynamic transition exhibited upon folding---was investigated from a microcanonical perspective: the accurate evaluation of the density of states can unambiguously characterize the nature of the transition, unlike its corresponding canonical analysis. Extending the results of lattice simulations and theoretical models, we find that it is the interplay between secondary structure and the loss of non-native tertiary contacts which determines the nature of the transition. Finally, we combine the peptide model with a high-resolution, solvent-free, lipid

  9. Reusing recycled aggregates in structural concrete

    Science.gov (United States)

    Kou, Shicong

    The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

  10. Coarse Grid CFD for underresolved simulation

    Science.gov (United States)

    Class, Andreas G.; Viellieber, Mathias O.; Himmel, Steffen R.

    2010-11-01

    CFD simulation of the complete reactor core of a nuclear power plant requires exceedingly huge computational resources so that this crude power approach has not been pursued yet. The traditional approach is 1D subchannel analysis employing calibrated transport models. Coarse grid CFD is an attractive alternative technique based on strongly under-resolved CFD and the inviscid Euler equations. Obviously, using inviscid equations and coarse grids does not resolve all the physics requiring additional volumetric source terms modelling viscosity and other sub-grid effects. The source terms are implemented via correlations derived from fully resolved representative simulations which can be tabulated or computed on the fly. The technique is demonstrated for a Carnot diffusor and a wire-wrap fuel assembly [1]. [4pt] [1] Himmel, S.R. phd thesis, Stuttgart University, Germany 2009, http://bibliothek.fzk.de/zb/berichte/FZKA7468.pdf

  11. Application of Coarse Integration to Bacterial Chemotaxis

    CERN Document Server

    Setayeshgar, S; Othmer, H G; Kevrekidis, Yu G

    2003-01-01

    We have developed and implemented a numerical evolution scheme for a class of stochastic problems in which the temporal evolution occurs on widely-separated time scales, and for which the slow evolution can be described in terms of a small number of moments of an underlying probability distribution. We demonstrate this method via a numerical simulation of chemotaxis in a population of motile, independent bacteria swimming in a prescribed gradient of a chemoattractant. The microscopic stochastic model, which is simulated using a Monte Carlo method, uses a simplified deterministic model for excitation/adaptation in signal transduction, coupled to a realistic, stochastic description of the flagellar motor. We show that projective time integration of ``coarse'' variables can be carried out on time scales long compared to that of the microscopic dynamics. Our coarse description is based on the spatial cell density distribution. Thus we are assuming that the system ``closes'' on this variable so that it can be desc...

  12. Coarse-grained Modeling of DNA Curvature

    CERN Document Server

    Freeman, Gordon S; Lequieu, Joshua P; Whitmer, Jonathan K; de Pablo, Juan J

    2014-01-01

    Modeling of DNA-protein interactions is a complex process involving many important time and length scales. This can be facilitated through the use of coarse-grained models which reduce the number of degrees of freedom and allow efficient exploration of binding configurations. It is known that the local structure of DNA can significantly affect its protein-binding properties (i.e. intrinsic curvature in DNA-histone complexes). In a step towards comprehensive DNA-protein modeling, we expand the 3SPN.2 coarse-grained model to include intrinsic shape, and validate the refined model against experimental data including melting temperature, local flexibility, persistence length, and minor groove width profile.

  13. Lightweight, Low-Power Coarse Star Tracker

    OpenAIRE

    Zenick, Ray; McGuire, Thomas

    2003-01-01

    General industry research on spacecraft attitude determination and control components is focused on increasing accuracy to the exclusion of all else. This is contrary to the clear requirement for decreased complexity, mass, and power consumption to fit the needs of small, maneuverable, low-cost spacecraft. To address this need, AeroAstro and the Massachusetts Institute of Technology Space Systems Laboratory are developing a coarse star tracker, which strikes an appropriate balance between acc...

  14. Increased corrosion resistance of basalt reinforced cement compositions with nanosilica

    Directory of Open Access Journals (Sweden)

    URKHANOVA Larisa Alekseevna

    2014-08-01

    Full Text Available Disperse fiber reinforcement is used to improve deformation and shrinkage characteristics, flexural strength of concrete. Basalt roving and thin staple fiber are often used as mineral fibers. The paper considers the problems of using thin basalt fiber produced by centrifugal-blow method. Evaluation of the corrosion resistance of basalt fiber as part of the cement matrix was performed. Nanodispersed silica produced by electron beam accelerator was used to increase corrosion resistance of basalt fiber.

  15. Structural relaxation in annealed hyperquenched basaltic glasses

    DEFF Research Database (Denmark)

    Guo, Xiaoju; Mauro, John C.; Potuzak, M.;

    2012-01-01

    The enthalpy relaxation behavior of hyperquenched (HQ) and annealed hyperquenched (AHQ) basaltic glass is investigated through calorimetric measurements. The results reveal a common onset temperature of the glass transition for all the HQ and AHQ glasses under study, indicating that the primary...

  16. The biological consequences of flood basalt volcanism

    Science.gov (United States)

    Clapham, M.

    2012-12-01

    Flood basalt eruptions are among the largest environmental perturbations of the Phanerozoic. The rapid release of CO2 from a large igneous province would have triggered a chain of events that can include climate warming, ocean acidification, reduced seawater carbonate saturation, and expanded oceanic anoxia. Those stressors have widely negative impacts on marine organisms, especially on calcified taxa, by affecting their respiratory physiology and reducing energy available for growth and reproduction. Many Phanerozoic extinctions, most notably the end-Permian and end-Triassic mass extinctions, coincided with flood basalt eruptions and shared distinctive patterns of taxonomic and ecological selectivity. In these extinctions, highly active organisms were more likely to survive because they possess physiological adaptations for maintaining internal pH during activity, which also proves useful when buffering pH against ocean acidification. In contrast, species that did not move and had low metabolic rates, such as brachiopods and sponges, suffered considerable losses during these extinctions. Heavily-calcified organisms, especially corals, were particularly vulnerable; as a result, ocean acidification and saturation state changes from flood basalt eruptions often triggered crises in reef ecosystems. This characteristic pattern of selectivity during "physiological" extinctions that closely coincided with flood basalts provides a template for assessing the causes of other extinction events. Because these crises also provide deep time analogues for the ongoing anthropogenic crisis of warming, ocean acidification, and expanded anoxia, the selectivity patterns can also help constrain "winners" and "losers" over upcoming decades.

  17. Site identification presentation: Basalt Waste Isolation Project

    International Nuclear Information System (INIS)

    The final step in the site identification process for the Basalt Waste Isolation Project is described. The candidate sites are identified. The site identification methodology is presented. The general objectives which must be met in selecting the final site are listed. Considerations used in the screening process are also listed. Summary tables of the guidelines used are included

  18. Thermal models for basaltic volcanism on Io

    Science.gov (United States)

    Keszthelyil, L.; McEwen, A.

    1997-01-01

    We present a new model for the thermal emissions from active basaltic eruptions on Io. While our methodology shares many similarities with previous work, it is significantly different in that (1) it uses a field tested cooling model and (2) the model is more applicable to pahoehoe flows and lava lakes than fountain-fed, channelized, 'a'a flows. This model demonstrates the large effect lava porosity has on the surface cooling rate (with denser flows cooling more slowly) and provides a preliminary tool for examining some of the hot spots on Io. The model infrared signature of a basaltic eruption is largely controlled by a single parameter, ??, the average survival time for a lava surface. During an active eruption surfaces are quickly covered or otherwise destroyed and typical values of ?? for a basaltic eruption are expected to be on the order of 10 seconds to 10 minutes. Our model suggests that the Galileo SSI eclipse data are consistent with moderately active to quiescent basaltic lava lakes but are not diagnostic of such activity. Copyright 1997 by the American Geophysical Union.

  19. Effect of Chopped Basalt Fibers on the Mechanical Properties and Microstructure of High Performance Fiber Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Tehmina Ayub

    2014-01-01

    Full Text Available This paper presents the mechanical properties and the microstructure of the high performance fiber reinforced concrete (HPFRC containing up to 3% volume fraction of chopped Basalt fibers. Three types of the concrete were prepared, out of which, the first type was prepared by utilizing 100% cement content. The other two types of the concrete were prepared by replacing 10% cement content with silica fume and the locally produced metakaolin. Using each concrete type, four mixes were prepared in which Basalt fibers were added in the range of 0–3%; that is, total twelve mixes of the HPFRC concrete were prepared. From each of the twelve concrete mixes, total twelve specimens were cast to determine the mechanical properties of the HPFRC including compressive strength (cube and cylinder, splitting tensile strength, and the flexural strength. In this way, a total of 108 specimens were cast and tested in this study. Test results showed that the addition of the Basalt fibers significantly increased the tensile splitting strength and the flexural strength of the HPFRC, while there was slight improvement in the compressive strength with the addition of Basalt fibers. The microstructure of HPFRC was examined to determine the interfacial transition zone (ITZ between the aggregates and the paste by using field emission scanning electron microscope (FESEM, which showed the improvement of the ITZ due to the addition of the Basalt fibers.

  20. Coatings on Atacama Desert Basalt: A Possible Analog for Coatings on Gusev Plains Basalt

    Science.gov (United States)

    Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

    2007-01-01

    Surface coatings on Gusev Plains basalt have been observed and may contain hematite and nanophase Fe-oxides along with enrichments in P, S, Cl, and K relative to the underlying rock. The Gusev coatings may be derived from the dissolution of adhering soil and/or parent rock along with the addition of S and Cl from outside sources. Transient water for dissolution could be sourced from melting snow during periods of high obliquity, acid fog, and/or ground water (Haskin et al., 2005). Coatings on basalt in the hyper-arid (less than 2mm y(sup -1)) Atacama Desert may assist in understanding the chemistry, mineralogy and formation mechanisms of the Gusev basalt coatings. The Atacama Desert climate is proposed to be analogous to a paleo-Mars climate that was characterized by limited aqueous activity when the Gusev coatings could have formed. The objectives of this work are to (i) determine the chemical nature and extent of surface coatings on Atacama Desert basalt, and (ii) assess coating formation mechanisms in the Atacama Desert. Preliminary backscattered electron imaging of Atacama basalt thin-sections indicated that the coatings are as thick as 20 m. The boundary between the coating and the basalt labradorite, ilmenite, and augite grains was abrupt indicating that the basalt minerals underwent no chemical dissolution. The Atacama coatings have been added to the basalt instead of being derived from basalt chemical weathering. Semi-quantitative energy dispersive spectroscopy shows the coatings to be chemically homogeneous. The coating is depleted in Ca (0.9 wt% CaO) and enriched in K (1.3 wt.% K2O) and Si (69.1 wt.% SiO2) relative to the augite and labradorite grains. A dust source enriched in Si (e.g., poorly crystalline silica) and K and depleted in Ca appears to have been added to the basalt surface. Unlike the Gusev coatings, no P, S, and Cl enrichment was observed. However, Fe (3.2 wt.% FeO) was present in the Atacama coatings suggesting the present of Fe

  1. Determination of the dynamic elastic constants of recycled aggregate concrete

    Science.gov (United States)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    Nowadays, construction and demolition waste constitutes a major portion of the total solid waste production in the world. Due to both environmental and economical reasons, an increasing interest concerning the use of recycled aggregate to replace aggregate from natural sources is generated. This paper presents an investigation on the properties of recycled aggregate concrete. Concrete mixes are prepared using recycled aggregates at a substitution level between 0 and 100% of the total coarse aggregate. The influence of this replacement on strengthened concrete's properties is being investigated. The properties estimated are: density and dynamic modulus of elasticity at the age of both 7 and 28 days. Also, flexural strength of 28 days specimens is estimated. The determination of the dynamic elastic modulus was made using the ultrasonic pulse velocity method. The results reveal that the existence of recycled aggregates affects the properties of concrete negatively; however, in low levels of substitution the influence of using recycled aggregates is almost negligible. Concluding, the controlled use of recycled aggregates in concrete production may help solve a vital environmental issue apart from being a solution to the problem of inadequate concrete aggregates.

  2. A closed-loop life cycle assessment of recycled aggregate concrete utilization in China.

    Science.gov (United States)

    Ding, Tao; Xiao, Jianzhuang; Tam, Vivian W Y

    2016-10-01

    This paper studies the potential environmental impact of recycled coarse aggregate (RCA) for concrete production in China. According to the cradle-to-cradle theory, a closed-loop life cycle assessment (LCA) on recycled aggregate concrete (RAC) utilization in China with entire local life cycle inventory (LCI) is performed, regarding the environmental influence of cement content, aggregate production, transportation and waste landfilling. Special attention is paid on the primary resource and energy conservation, as well as climate protection induced by RAC applications. Environmental impact between natural aggregate concrete (NAC) and RAC are also compared. It is shown that cement proportion and transportation are the top two contributors for carbon dioxide (CO2) emissions and energy consumption for both NAC and RAC. Sensitivity analysis also proves that long delivery distances for natural coarse aggregate (NCA) leave a possible opportunity for lowering environmental impact of RAC in China. PMID:27297045

  3. Investigations on Fresh and Hardened Properties of Recycled Aggregate Self Compacting Concrete

    Science.gov (United States)

    Revathi, P.; Selvi, R. S.; Velin, S. S.

    2013-09-01

    In the recent years, construction and demolition waste management issues have attracted the attention from researchers around the world. In the present study, the potential usage of recycled aggregate obtained from crushed demolition waste for making self compacting concrete (SCC) was researched. The barriers in promoting the use of recycled material in new construction are also discussed. In addition, the results of an experimental study involving the use of recycled concrete aggregate as coarse aggregates for producing self-compacting concrete to study their flow and strength characteristics are also presented. Five series of mixture were prepared with 0, 25, 50, 75, and 100 % coarse recycled aggregate adopting Nan Su's mix proportioning method. The fresh concrete properties were evaluated through the slump flow, J-ring and V-funnel tests. Compressive and tensile strengths were also determined. The results obtained showed that SCC could be successfully developed by incorporating recycled aggregates.

  4. A closed-loop life cycle assessment of recycled aggregate concrete utilization in China.

    Science.gov (United States)

    Ding, Tao; Xiao, Jianzhuang; Tam, Vivian W Y

    2016-10-01

    This paper studies the potential environmental impact of recycled coarse aggregate (RCA) for concrete production in China. According to the cradle-to-cradle theory, a closed-loop life cycle assessment (LCA) on recycled aggregate concrete (RAC) utilization in China with entire local life cycle inventory (LCI) is performed, regarding the environmental influence of cement content, aggregate production, transportation and waste landfilling. Special attention is paid on the primary resource and energy conservation, as well as climate protection induced by RAC applications. Environmental impact between natural aggregate concrete (NAC) and RAC are also compared. It is shown that cement proportion and transportation are the top two contributors for carbon dioxide (CO2) emissions and energy consumption for both NAC and RAC. Sensitivity analysis also proves that long delivery distances for natural coarse aggregate (NCA) leave a possible opportunity for lowering environmental impact of RAC in China.

  5. H 2O in basalt and basaltic andesite glass inclusions from four subduction-related volcanoes

    Science.gov (United States)

    Sisson, T. W.; Layne, G. D.

    1993-06-01

    Total dissolved H 2O and major element abundances were measured in basalt and basaltic andesite glass inclusions in olivine phenocrysts from Quaternary eruptions of four subduction-related volcanoes to test the hypothesis that low-MgO high-alumina basalts contain high H 2O at depth [1] and to reveal any petrogenetically significant correlations between arc basalt compositions and H 2O contents. Total dissolved H 2O (combined molecular H 2O and OH groups) measured by ion microprobe in mafic glass inclusions from the 1974 eruption of Fuego, Guatemala, reaches 6.2 wt.%. Dissolved H 2O contents decrease in more evolved Fuego glasses. Correlations of H 2O with MgO, Na 2O, K 2O, S and Cl indicate that aqueous fluid exsolution during magma ascent forced crystallization and differentiation of residual liquids. Low-K 2O magnesian high-alumina basalt glass inclusions from the 3 ka eruption of Black Crater (Medicine Lake volcano, California) have low H 2O contents, near 0.2 wt.%, which are consistent with the MORB-like character of these and other primitive lavas of the Medicine Lake region. Basalt and basaltic andesite glass inclusions from Copco Cone and Goosenest volcano on the Cascade volcanic front north of Mt. Shasta have H 2O contents of up to 3.3 wt.%. The range of H 2O contents in Cascade mafic magmas is too large to have resulted solely from enrichment by crystallization and indicates the participation of an H 2O-rich component in magma generation or crustal-level modification. Whereas fluid-absent melting of amphibole-bearing peridotite can account for the H 2O in most mafic arc liquids, the very high H 2O/alkali ratios of the 1974 Fuego eruptives suggest that an aqueous fluid was involved in the generation of Fuego basalts.

  6. Sulfur isotope homogeneity of lunar mare basalts

    Science.gov (United States)

    Wing, Boswell A.; Farquhar, James

    2015-12-01

    We present a new set of high precision measurements of relative 33S/32S, 34S/32S, and 36S/32S values in lunar mare basalts. The measurements are referenced to the Vienna-Canyon Diablo Troilite (V-CDT) scale, on which the international reference material, IAEA-S-1, is characterized by δ33S = -0.061‰, δ34S ≡ -0.3‰ and δ36S = -1.27‰. The present dataset confirms that lunar mare basalts are characterized by a remarkable degree of sulfur isotopic homogeneity, with most new and published SF6-based sulfur isotope measurements consistent with a single mass-dependent mean isotopic composition of δ34S = 0.58 ± 0.05‰, Δ33S = 0.008 ± 0.006‰, and Δ36S = 0.2 ± 0.2‰, relative to V-CDT, where the uncertainties are quoted as 99% confidence intervals on the mean. This homogeneity allows identification of a single sample (12022, 281) with an apparent 33S enrichment, possibly reflecting cosmic-ray-induced spallation reactions. It also reveals that some mare basalts have slightly lower δ34S values than the population mean, which is consistent with sulfur loss from a reduced basaltic melt prior to eruption at the lunar surface. Both the sulfur isotope homogeneity of the lunar mare basalts and the predicted sensitivity of sulfur isotopes to vaporization-driven fractionation suggest that less than ≈1-10% of lunar sulfur was lost after a potential moon-forming impact event.

  7. Compression Dispersion Efficiency of Recycled Aggregate Concrete Struts At Different Load Concentration Ratios

    Directory of Open Access Journals (Sweden)

    Dr. Rakesh Kumar, Dr.P.K Mehta,Devbrat Singh, Anup Kumar Pandey, Sarvesh Kumar

    2014-06-01

    Full Text Available Infrastructure development activities in India have increased many folds in recent times. This has resulted in increase in the demand of construction materials like cement, coarse aggregate, fine aggregate etc. Huge quantities of concrete wastes are produced due to demolition of old structures. If recycled aggregate from this waste is used for construction purpose, it will not only make the structures economical and eco-friendly butwill also solve the problem of waste disposal.Recycling old waste concrete by crushing and grading into coarse aggregates for use in new structural concrete is drawing the attention of engineers, environmentalists and researchers since last three decades. In this paper, an attempt has been made to study the compression dispersion behaviour of struts of natural coarse aggregate (NCA and recycle coarse aggregate (RCA at different load concentration ratio and aspect ratio. For the study, struts of 450 mm height and 75mm thickness with varying widths starting from 75mm to 450mm, using NCA and RCA concrete, were cast. The testing of struts was carriedout on loading frame of capacity 500 kN. The struts were tested to failure under in-plane compressive load applied through symmetrically placed steel plate (75×75×10 mm at top andbottom of the struts.

  8. Aggregating Reputation Feedback

    OpenAIRE

    Garcin, Florent; Faltings, Boi; Jurca, Radu

    2009-01-01

    A fundamental task in reputation systems is to aggregate multiple feedback ratings into a single value that can be used to compare the reputation of different entities. Feedback is most commonly aggregated using the arithmetic mean. However, the mean is quite susceptible to outliers and biases, and thus may not be the most informative aggregate of the reports. We consider three criteria to assess the quality of an aggregator: the informativness, the robustness and the strategyproofness, and a...

  9. Geochemistry of apollo 15 basalt 15555 and soil 15531.

    Science.gov (United States)

    Schnetzler, C C; Philpotts, J A; Nava, D F; Schuhmann, S; Thomas, H H

    1972-01-28

    Major and trace element concentrations have been determined by atomic absorption spectrophotometry, colorimetry, and isotope dilution in Apollo 15 mare basalt 15555 from the Hadley Rille area; trace element concentrations have also been determined in plagioclase and pyroxene separates from basalt 15555 and in soil 15531 from the same area. Basalt 15555 most closely resembles in composition the Apollo 12 olivine-rich basalts. The concentrations of lithium, potassium, rubidium, barium, rare-earth elements, and zirconium in basalt 15555 are the lowest, and the negative europium anomaly is the smallest, reported for lunar basalts; this basalt might be the least differentiated material yet returned from the moon. Crystallization and removal of about 6 percent of plagioclase similar to that contained in the basalt would account for the observed europium anomaly; if plagioclase is not on the liquidus of this basalt, a multistage origin is indicated. Mineral data indicate that plagioclase and pyroxene approached quasi-equilibrium. Most of the chemical differences between basalt 15555 and soil 15531 would be accounted for if the soil were a mixture of 88 percent basalt, 6 percent KREEP (a component, identified in other Apollo soils, rich in potassium, rare-earth elements, and phosphorus) and 6 percent plagioclase (anorthosite?).

  10. The gravitational description of coarse grained microstates

    Energy Technology Data Exchange (ETDEWEB)

    Alday, Luis F. [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht (Netherlands); Boer, Jan de [Instituut voor Theoretische Fysica, Valckenierstraat 65, 1018XE Amsterdam (Netherlands); Messamah, Ilies [Instituut voor Theoretische Fysica, Valckenierstraat 65, 1018XE Amsterdam (Netherlands)

    2006-12-15

    In this paper we construct a detailed map from pure and mixed half-BPS states of the D1-D5 system to half-BPS solutions of type IIB supergravity. Using this map, we can see how gravity arises through coarse graining microstates, and we can explicitly confirm the microscopic description of conical defect metrics, the M = 0 BTZ black hole and of small black rings. We find that the entropy associated to the natural geometric stretched horizon typically exceeds that of the mixed state from which the geometry was obtained.

  11. An algebraic approach to coarse graining

    CERN Document Server

    Markopoulou, F

    2000-01-01

    We propose that Kreimer's method of Feynman diagram renormalization via a Hopf algebra of rooted trees can be fruitfully employed in the analysis of block spin renormalization or coarse graining of inhomogeneous statistical systems. Examples of such systems include spin foam formulations of non-perturbative quantum gravity as well as lattice gauge and spin systems on irregular lattices and/or with spatially varying couplings. We study three examples which are Z_2 lattice gauge theory on irregular 2-dimensional lattices, Ising/Potts models with varying bond strengths and (1+1)-dimensional spin foam models.

  12. Petrology, geochemistry, and age of low-Ti mare-basalt meteorite Northeast Africa 003-A: A possible member of the Apollo 15 mare basaltic suite

    Science.gov (United States)

    Haloda, Jakub; Týcová, Patricie; Korotev, Randy L.; Fernandes, Vera A.; Burgess, Ray; Thöni, Martin; Jelenc, Monika; Jakeš, Petr; Gabzdyl, Pavel; Košler, Jan

    2009-06-01

    Northeast Africa 003 (NEA 003) is a lunar meteorite found as a two paired stones (6 and 118 g) in Libya, 2000 and 2001. The main portion (˜75 vol%) of the 118 g meteorite, used for this study, (NEA 003-A) consists of mare-basalt and a smaller adjacent portion (˜25 vol%) is a basaltic breccia (NEA 003-B). NEA 003-A has a coarse-grained magmatic texture consisting mainly of olivine, pyroxene and plagioclase. The late-stage mineral association is composed mainly of elongated plagioclase, ilmenite, troilite, fayalite, Si-K-rich glass, apatite, and a rare SiO 2 phase. Other accessory minerals include ulvöspinel, chromite, and trace Fe-Ni metal. Olivine and pyroxene contain shock-induced fractures, and plagioclase is completely converted into maskelynite. The Fe/Mn values of the whole rock, olivines and pyroxenes, and the bulk-rock oxygen isotopic composition provide evidence for the lunar origin of NEA 003-A meteorite. This is further supported by the presence of Fe-Ni metal and the anhydrous mineral association. NEA 003-A is geochemically and petrographically distinct from previously described mare-basalt meteorites and is not paired with any of them. The petrography and major element composition of NEA 003-A is similar to the composition of low-Ti olivine mare basalts from Apollo 12 and olivine-normative basalts from Apollo 15. The NEA 003-A meteorite shows obvious geochemical similarities in trace elements contents with Apollo 15 olivine-normative basalts and could represent a yet unknown geochemically primitive member of the olivine-normative basalt series. The meteorite is depleted in rare earth elements (REE) and incompatible trace elements indicating a primitive character of the parental magma. The bulk-rock chemical composition demonstrates that the parent melt of NEA 003-A was not contaminated with KREEP components as a result of magma mixing or assimilation processes. Results of crystallization modelling and low minimum cooling rate estimates (˜0.07

  13. Northwest Africa 5298: A Basaltic Shergottite

    Science.gov (United States)

    Hui, Hejiu; Peslier, Anne; Lapen, Thomas J.; Brandon, Alan; Shafer, John

    2009-01-01

    NWA 5298 is a single 445 g meteorite found near Bir Gandouz, Morocco in March 2008 [1]. This rock has a brown exterior weathered surface instead of a fusion crust and the interior is composed of green mineral grains with interstitial dark patches containing small vesicles and shock melts [1]. This meteorite is classified as a basaltic shergottite [2]. A petrologic study of this Martian meteorite is being carried out with electron microprobe analysis and soon trace element analyses by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Oxygen fugacity is calculated from Fe-Ti oxides pairs in the sample. The data from this study constrains the petrogenesis of basaltic shergottites.

  14. Laboratory evaluation of cement treated aggregate containing crushed clay brick

    Directory of Open Access Journals (Sweden)

    Liqun Hu

    2014-10-01

    Full Text Available The waste clay bricks from debris of buildings were evaluated through lab tests as environmental friendly materials for pavement sub-base in the research. Five sets of coarse aggregates which contained 0, 25%, 50%, 75% and 100% crushed bricks, respectively, were blended with sand and treated by 5% cement. The test results indicated that cement treated aggregate which contains crushed clay brick aggregate had a lower maximum dry density (MDD and a higher optimum moisture content (OMC. Moreover, the unconfined compressive strength (UCS, resilience modulus, splitting strength, and frost resistance performance of the specimens decreased with increase of the amount of crushed clay brick aggregate. On the other hand, it can be observed that the use of crushed clay brick in the mixture decreased the dry shrinkage strain of the specimens. Compared with the asphalt pavement design specifications of China, the results imply that the substitution rate of natural aggregate with crushed clay brick aggregate in the cement treated aggregate sub-base material should be less than 50% (5% cement content in the mixture. Furthermore, it needs to be noted that the cement treated aggregate which contains crushed clay bricks should be cautiously used in the cold region due to its insufficient frost resistance performance.

  15. SOIL AGGREGATE AND ITS RESPONSE TO LAND MANAGEMENT PRACTICES

    Institute of Scientific and Technical Information of China (English)

    Chaofu Wei; Ming Gao; Jingan Shao; Deti Xie; Genxing Pan

    2006-01-01

    This paper provides a broad review of the existing study on soil aggregate and its responses to land management practices. Soil aggregate is used for structural unit, which is a group of primary soil particles that cohere to each other more strongly than other surrounding particles. The mechanism of soil particle aggregation may be expressed by a hierarchical model, which is based upon the hypothesis that macroaggregates (>250 μm) are collections of smaller microaggregates (<250 μm) held together with organic binding agents. Primary particles form microaggregates and then macroaggregates. Carbon (C)-rich young plant residues form and stabilize macroaggregates, whereas old organic C is occluded in the microaggregates. The interaction of aggregate dynamics with soil organic carbon (SOC) is complex and embraces a range of spatial and temporal processes within macroaggregates and microaggregates. The nature and properties of aggregates are determined by the quantity and quality of coarse residues and humic compounds and by the degree of their interaction with soil particles. The mechanisms resulting in the binding of primary soil particles into stable aggregates vary with soil parent material, climate, vegetation, and land management practices. Land management practices, including tillage methods, residue management, amendments, and soil fertility management, enhance soil aggregation. However, there is still much uncertainty in the dynamics of organic matter in macroaggregation and microaggregation, and research is still needed to understand further the mechanisms of aggregate formation and its responses to human activities.

  16. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    Hisham Qasrawi

    2013-01-01

    Full Text Available The effect of using recycled concrete aggregates (RCA on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates has an adverse effect on the workability and air content of fresh concrete. Depending on the water/cement ratio and on the percent of the normal aggregate replaced by RCA, the concrete strength is reduced by 5% to 25%, while the tensile strength is reduced by 4% to 14%. All results are compared with previous research. As new in this research, the paper introduces a simple formula for the prediction of the modulus of elasticity of RCA concrete. Furthermore, the paper shows the variation of the air content of RAC.

  17. Technical program plan, Basalt Waste Isolation Project

    International Nuclear Information System (INIS)

    The Basalt Waste Isolation Project (BWIP) program as administered by the DOE's Richland Operations Office and Rockwell Hanford Operations is described. The objectives, scope and scientific technologies are discussed. The work breakdown structure of the project includes: project management and support, systems integration, geosciences, hydrology, engineered barriers, test facility design and construction, engineering testing, repository studies, and schedules. The budget of the program including operating and capital cost control is also included

  18. Nanoparticulate mineral matter from basalt dust wastes.

    Science.gov (United States)

    Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

    2016-02-01

    Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region.

  19. Technical program plan, Basalt Waste Isolation Project

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-12-01

    The Basalt Waste Isolation Project (BWIP) program as administered by the DOE's Richland Operations Office and Rockwell Hanford Operations is described. The objectives, scope and scientific technologies are discussed. The work breakdown structure of the project includes: project management and support, systems integration, geosciences, hydrology, engineered barriers, test facility design and construction, engineering testing, repository studies, and schedules. The budget of the program including operating and capital cost control is also included. (DC)

  20. Nanoparticulate mineral matter from basalt dust wastes.

    Science.gov (United States)

    Dalmora, Adilson C; Ramos, Claudete G; Querol, Xavier; Kautzmann, Rubens M; Oliveira, Marcos L S; Taffarel, Silvio R; Moreno, Teresa; Silva, Luis F O

    2016-02-01

    Ultra-fine and nano-particles derived from basalt dust wastes (BDW) during "stonemeal" soil fertilizer application have been the subject of some concern recently around the world for their possible adverse effects on human health and environmental pollution. Samples of BDW utilized were obtained from companies in the mining district of Nova Prata in southern Brazil for chemical characterization and nano-mineralogy investigation, using an integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS and granulometric distribution analysis. The investigation has revealed that BDW materials are dominated by SiO2, Al2O3 and Fe2O3, with a complex micromineralogy including alkali feldspar, augite, barite, labradorite, hematite, heulandrite, gypsum, kaolinite, quartz, and smectite. In addition we have identified a number of trace metals such as Cd, Cu, Cr, Zn that are preferentially concentrated into the finer, inhalable, dust fraction and could so present a health hazard in the urban areas around the basalt mining zone. The implication of this observation is that use of these nanometric-sized particulates as soil fertilizer may present different health challenges to those of conventional fertilizers, inviting future work regarding the relative toxicities of these materials. Our investigation on the particle size distribution, nano-particle mineralogy and chemical composition in typical BDW samples highlights the need to develop cleaning procedures to minimise exposure to these natural fertilizing basalt dust wastes and is thus of direct relevance to both the industrial sector of basalt mining and to agriculture in the region. PMID:26551199

  1. Effects of maximum aggregate size on UPV of brick aggregate concrete.

    Science.gov (United States)

    Mohammed, Tarek Uddin; Mahmood, Aziz Hasan

    2016-07-01

    Investigation was carried out to study the effects of maximum aggregate size (MAS) (12.5mm, 19.0mm, 25.0mm, 37.5mm, and 50.0mm) on ultrasonic pulse velocity (UPV) of concrete. For investigation, first class bricks were collected and broken to make coarse aggregate. The aggregates were tested for specific gravity, absorption capacity, unit weight, and abrasion resistance. Cylindrical concrete specimens were made with different sand to aggregate volume ratio (s/a) (0.40 and 0.45), W/C ratio (0.45, 0.50, and 0.55), and cement content (375kg/m(3) and 400kg/m(3)). The specimens were tested for compressive strength and Young's modulus. UPV through wet specimen was measured using Portable Ultrasonic Non-destructive Digital Indicating Tester (PUNDIT). Results indicate that the pulse velocity through concrete increases with an increase in MAS. Relationships between UPV and compressive strength; and UPV and Young's modulus of concrete are proposed for different maximum sizes of brick aggregate. PMID:27085110

  2. Effects of maximum aggregate size on UPV of brick aggregate concrete.

    Science.gov (United States)

    Mohammed, Tarek Uddin; Mahmood, Aziz Hasan

    2016-07-01

    Investigation was carried out to study the effects of maximum aggregate size (MAS) (12.5mm, 19.0mm, 25.0mm, 37.5mm, and 50.0mm) on ultrasonic pulse velocity (UPV) of concrete. For investigation, first class bricks were collected and broken to make coarse aggregate. The aggregates were tested for specific gravity, absorption capacity, unit weight, and abrasion resistance. Cylindrical concrete specimens were made with different sand to aggregate volume ratio (s/a) (0.40 and 0.45), W/C ratio (0.45, 0.50, and 0.55), and cement content (375kg/m(3) and 400kg/m(3)). The specimens were tested for compressive strength and Young's modulus. UPV through wet specimen was measured using Portable Ultrasonic Non-destructive Digital Indicating Tester (PUNDIT). Results indicate that the pulse velocity through concrete increases with an increase in MAS. Relationships between UPV and compressive strength; and UPV and Young's modulus of concrete are proposed for different maximum sizes of brick aggregate.

  3. Coarse graining flow of spin foam intertwiners

    CERN Document Server

    Dittrich, Bianca; Seth, Cameron J; Steinhaus, Sebastian

    2016-01-01

    Simplicity constraints play a crucial role in the construction of spin foam models, yet their effective behaviour on larger scales is scarcely explored. In this article we introduce intertwiner and spin net models for the quantum group $\\text{SU}(2)_k \\times \\text{SU}(2)_k$, which implement the simplicity constraints analogous to 4D Euclidean spin foam models, namely the Barrett-Crane (BC) and the Engle-Pereira-Rovelli-Livine/Freidel-Krasnov (EPRL/FK) model. These models are numerically coarse grained via tensor network renormalization, allowing us to trace the flow of simplicity constraints to larger scales. In order to perform these simulations we have substantially adapted tensor network algorithms, which we discuss in detail. The BC and the EPRL/FK model behave very differently under coarse graining: While the unique BC intertwiner model is a fixed point and therefore constitutes a 2D topological phase, BC spin net models flow away from the initial simplicity constraints and converge to several different ...

  4. Coarse-Grain Modeling of Energetic Materials

    Science.gov (United States)

    Brennan, John

    2015-06-01

    Mechanical and thermal loading of energetic materials can incite responses over a wide range of spatial and temporal scales due to inherent nano- and microscale features. Many energy transfer processes within these materials are atomistically governed, yet the material response is manifested at the micro- and mesoscale. The existing state-of-the-art computational methods include continuum level approaches that rely on idealized field-based formulations that are empirically based. Our goal is to bridge the spatial and temporal modeling regimes while ensuring multiscale consistency. However, significant technical challenges exist, including that the multiscale methods linking the atomistic and microscales for molecular crystals are immature or nonexistent. To begin addressing these challenges, we have implemented a bottom-up approach for deriving microscale coarse-grain models directly from quantum mechanics-derived atomistic models. In this talk, a suite of computational tools is described for particle-based microscale simulations of the nonequilibrium response of energetic solids. Our approach builds upon recent advances both in generating coarse-grain models under high strains and in developing a variant of dissipative particle dynamics that includes chemical reactions.

  5. Equilibrium behavior of coarse-grained chaos

    Science.gov (United States)

    Egolf, David A.; Ballard, Christopher C.; Esty, C. Clark

    2015-03-01

    A wide variety of systems exhibiting spatiotemporal chaos have been shown to be extensive, in that their fractal dimensions grow linearly with volume. Ruelle argued that this extensivity is evidence that these systems can be viewed as a gas of weakly-interacting regions. We have tested this idea by performing large-scale computational studies of spatiotemporal chaos in the 1D complex Ginzburg-Landau equation, and we have found that aspects of the coarse-grained system are well-described not only as a gas, but as an equilibrium gas -- in particular, a Tonks gas (and variants) in the grand canonical ensemble. Furthermore, for small system sizes, the average number of particles in the corresponding Tonks gas exhibits oscillatory, decaying deviations from extensivity in agreement with deviations in the fractal dimension found by Fishman and Egolf. This result not only supports Ruelle's picture but also suggests that the coarse-grained behavior of this far-from-equilibrium system might be understood using equilibrium statistical mechanics.

  6. Effect of Glass Powder on Chloride Ion Transport and Alkali-aggregate Reaction Expansion of Lightweight Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi; SHI Caijun; SONG Jianming

    2009-01-01

    The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated.Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re-placement of cement with 25% glass powder slightly decreases the strengthes at 7 and 28 d, but shows no effect on 90 d's. Silica fume is very effective in improving both the strength and chloride penetra-tion resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete.

  7. Comparing non-parametric methods for ungrouping coarsely aggregated age-specific distributions

    DEFF Research Database (Denmark)

    Rizzi, Silvia; Thinggaard, Mikael; Vaupel, James W.;

    2016-01-01

    ., 2015). Recently a novel non-parametric method, based on the composite link model with a penalized likelihood, has been proposed (Rizzi et al., 2015). Here we aim to examine the performance of these different ungrouping methods in an empirical application with particular focus on the open-ended last...... interval. To do so we compare original NORDCAN data by single-year of age with the estimated distributions resulting from the models. We show that the penalized composite link model outperforms spline interpolation methods in presence of wide open-ended intervals....

  8. Comparison of non-parametric methods for ungrouping coarsely aggregated data

    DEFF Research Database (Denmark)

    Rizzi, Silvia; Thinggaard, Mikael; Engholm, Gerda;

    2016-01-01

    methods for ungrouping count data. We compare the performance of two spline interpolation methods, two kernel density estimators and a penalized composite link model first via a simulation study and then with empirical data obtained from the NORDCAN Database. All methods analyzed can be used to estimate...... differently shaped distributions; can handle unequal interval length; and allow stretches of 0 counts. Results The methods show similar performance when the grouping scheme is relatively narrow, i.e. 5-years age classes. With coarser age intervals, i.e. in the presence of open-ended age groups, the penalized...... composite link model performs the best. Conclusion We give an overview and test different methods to estimate detailed distributions from grouped count data. Health researchers can benefit from these versatile methods, which are ready for use in the statistical software R. We recommend using the penalized...

  9. Stratigraphical framework of basaltic lavas in Torres Syncline main valley, southern Parana-Etendeka Volcanic Province

    Science.gov (United States)

    Rossetti, Lucas M.; Lima, Evandro F.; Waichel, Breno L.; Scherer, Claiton M.; Barreto, Carla J.

    2014-12-01

    The Paraná-Etendeka Volcanic Province records the volcanism of the Early Cretaceous that precedes the fragmentation of the South-Gondwana supercontinent. Traditionally, investigations of these rocks prioritized the acquisition of geochemical and isotopic data, considering the volcanic stack as a monotonous succession of tabular flows. Torres Syncline is a tectonic structure located in southern Brazil and where the Parana-Etendeka basalts are well preserved. This work provides a detailed analysis of lithofacies and facies architecture, integrated to petrographic and geochemical data. We identified seven distinct lithofacies grouped into four facies associations related to different flow morphologies. The basaltic lava flows in the area can be divided into two contrasting units: Unit I - pahoehoe flow fields; and Unit II - simple rubbly flows. The first unit is build up by innumerous pahoehoe lava flows that cover the sandstones of Botucatu Formation. These flows occur as sheet pahoehoe, compound pahoehoe, and ponded lavas morphologies. Compound lavas are olivine-phyric basalts with intergranular pyroxenes. In ponded lavas and cores of sheet flows coarse plagioclase-phyric basalts are common. The first pahoehoe lavas are more primitive with higher contents of MgO. The emplacement of compound pahoehoe flows is related to low volume eruptions, while sheet lavas were emplaced during sustained eruptions. In contrast, Unit II is formed by thick simple rubbly lavas, characterized by a massive core and a brecciated/rubbly top. Petrographically these flows are characterized by plagioclase-phyric to aphyric basalts with high density of plagioclase crystals in the matrix. Chemically they are more differentiated lavas, and the emplacement is related to sustained high effusion rate eruptions. Both units are low TiO2 and have geochemical characteristics of Gramado magma type. The Torres Syncline main valley has a similar evolution when compared to other Large Igneous Provinces

  10. Compressive strength and resistance to chloride ion penetration and carbonation of recycled aggregate concrete with varying amount of fly ash and fine recycled aggregate.

    Science.gov (United States)

    Sim, Jongsung; Park, Cheolwoo

    2011-11-01

    Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members. PMID:21784626

  11. Making rhyolite in a basalt crucible

    Science.gov (United States)

    Eichelberger, John

    2016-04-01

    Iceland has long attracted the attention of those concerned with the origin of rhyolitic magmas and indeed of granitic continental crust, because it presents no alternative for such magmas other than deriving them from a basaltic source. Hydrothermally altered basalt has been identified as the progenitor. The fact that rhyolite erupts as pure liquid requires a process of melt-crustal separation that is highly efficient despite the high viscosity of rhyolite melt. Volcanoes in Iceland are foci of basaltic magma injection along the divergent plate boundary. Repeated injection produces remelting, digestion, and sometimes expulsion or lateral withdrawal of material resulting in a caldera, a "crucible" holding down-dropped and interlayered lava flows, tephras, and injected sills. Once melting of this charge begins, a great deal of heat is absorbed in the phase change. Just 1% change in crystallinity per degree gives a melt-present body an effective heat capacity >5 times the subsolidus case. Temperature is thus buffered at the solidus and melt composition at rhyolite. Basalt inputs are episodic ("fires") so likely the resulting generation of rhyolite by melting is too. If frequent enough to offset cooling between events, rhyolite melt extractions will accumulate as a rhyolite magma reservoir rather than as discrete crystallized sills. Evidently, such magma bodies can survive multiple firings without themselves erupting, as the 1875 eruption of Askja Caldera of 0.3 km3 of rhyolite equilibrated at 2-km depth without previous leakage over a ten-millennium period and the surprise discovery of rhyolite magma at 2-km depth in Krafla suggest. Water is required for melting; otherwise melting cannot begin at a temperature lower than that of the heat source. Because the solubility of water in melt is pressure-dependent and almost zero at surface pressure, there must be a minimum depth at which basalt-induced melting can occur and a rhyolite reservoir sustained. In practice, the

  12. Diffusion in aggregated soil.

    OpenAIRE

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consists of spherical, or cylindrical or plane aggregates, which do not represent the individual aggregates of the soil, however. The radii of the spheres, cylinders or plane sheets represent different le...

  13. Provenance for Aggregate Queries

    OpenAIRE

    Yael Amsterdamer; Daniel Deutch; Val Tannen

    2011-01-01

    We study in this paper provenance information for queries with aggregation. Provenance information was studied in the context of various query languages that do not allow for aggregation, and recent work has suggested to capture provenance by annotating the different database tuples with elements of a commutative semiring and propagating the annotations through query evaluation. We show that aggregate queries pose novel challenges rendering this approach inapplicable. Consequently, we propose...

  14. An Information-Theoretic Perspective on Coarse-Graining, Including the Transition from Micro to Macro

    Directory of Open Access Journals (Sweden)

    Kristian Lindgren

    2015-05-01

    Full Text Available An information-theoretic perspective on coarse-graining is presented. It starts with an information characterization of configurations at the micro-level using a local information quantity that has a spatial average equal to a microscopic entropy. With a reversible micro dynamics, this entropy is conserved. In the micro-macro transition, it is shown how this local information quantity is transformed into a macroscopic entropy, as the local states are aggregated into macroscopic concentration variables. The information loss in this transition is identified, and the connection to the irreversibility of the macro dynamics and the second law of thermodynamics is discussed. This is then connected to a process of further coarse-graining towards higher characteristic length scales in the context of chemical reaction-diffusion dynamics capable of pattern formation. On these higher levels of coarse-graining, information flows across length scales and across space are defined. These flows obey a continuity equation for information, and they are connected to the thermodynamic constraints of the system, via an outflow of information from macroscopic to microscopic levels in the form of entropy production, as well as an inflow of information, from an external free energy source, if a spatial chemical pattern is to be maintained.

  15. The Aggregate-Supply/Aggregate-Demand Model

    OpenAIRE

    BARRO, Robert J.

    1994-01-01

    The aggregate-supply/ aggregate-demand (AS-AD) model is popular in textbooks, but has problems with logical consistency. In one interpretation, the Keynesian underpinnings of the AD curve-derived from the IS/LM model with downward price stickiness-conflict with the determination of the price level at the intersection of the AS and AD curves. In another view, the model corresponds to rational-expectations theories in which Keynesian properties are absent. In a third interpretation, the model i...

  16. Virtual Screening for Dipeptide Aggregation: Toward Predictive Tools for Peptide Self-Assembly

    Science.gov (United States)

    2011-01-01

    Several short peptide sequences are known to self-assemble into supramolecular nanostructures with interesting properties. In this study, coarse-grained molecular dynamics is employed to rapidly screen all 400 dipeptide combinations and predict their ability to aggregate as a potential precursor to their self-assembly. The simulation protocol and scoring method proposed allows a rapid determination of whether a given peptide sequence is likely to aggregate (an indicator for the ability to self-assemble) under aqueous conditions. Systems that show strong aggregation tendencies in the initial screening are selected for longer simulations, which result in good agreement with the known self-assembly or aggregation of dipeptides reported in the literature. Our extended simulations of the diphenylalanine system show that the coarse-grain model is able to reproduce salient features of nanoscale systems and provide insight into the self-assembly process for this system. PMID:23795243

  17. Virtual Screening for Dipeptide Aggregation: Toward Predictive Tools for Peptide Self-Assembly.

    Science.gov (United States)

    Frederix, Pim W J M; Ulijn, Rein V; Hunt, Neil T; Tuttle, Tell

    2011-10-01

    Several short peptide sequences are known to self-assemble into supramolecular nanostructures with interesting properties. In this study, coarse-grained molecular dynamics is employed to rapidly screen all 400 dipeptide combinations and predict their ability to aggregate as a potential precursor to their self-assembly. The simulation protocol and scoring method proposed allows a rapid determination of whether a given peptide sequence is likely to aggregate (an indicator for the ability to self-assemble) under aqueous conditions. Systems that show strong aggregation tendencies in the initial screening are selected for longer simulations, which result in good agreement with the known self-assembly or aggregation of dipeptides reported in the literature. Our extended simulations of the diphenylalanine system show that the coarse-grain model is able to reproduce salient features of nanoscale systems and provide insight into the self-assembly process for this system. PMID:23795243

  18. Coarse graining in spin foam models

    Energy Technology Data Exchange (ETDEWEB)

    Markopoulou, Fotini

    2003-03-07

    We formulate the problem of finding the low-energy limit of spin foam models as a coarse-graining problem in the sense of statistical physics. This suggests that renormalization group methods may be used to find that limit. However, since spin foams are models of spacetime at the Planck scale, novel issues arise: these microscopic models are sums over irregular, background-independent lattices. We show that all of these issues can be addressed by the recent application of the Kreimer Hopf algebra for quantum field theory renormalization to non-perturbative statistical physics. The main difference from the standard renormalization group is that the Hopf algebra executes block transformations in parts of the lattice only but in a controlled manner so that the end result is a fully block-transformed lattice.

  19. Adaptive Coarse Graining, Environment, Strong Decoherence, and Quasiclassical Realms

    CERN Document Server

    Gell-Mann, Murray

    2013-01-01

    Three ideas are introduced that when brought together characterize the realistic quasiclassical realms of our quantum universe as particular kinds of sets of alternative coarse-grained histories defined by quasiclassical variables: (1) Branch dependent adaptive coarse grainings that can be close to maximally refined and can simplify calculation. (2) Narrative coarse grainings that describe how features of the universe change over time and allow the construction of an environment. (3) A notion of strong decoherence that characterizes realistic mechanisms of decoherence.

  20. An analysis of Apollo lunar soil samples 12070,889, 12030,187, and 12070,891: Basaltic diversity at the Apollo 12 landing site and implications for classification of small-sized lunar samples

    Science.gov (United States)

    Alexander, Louise; Snape, Joshua F.; Joy, Katherine H.; Downes, Hilary; Crawford, Ian A.

    2016-09-01

    Lunar mare basalts provide insights into the compositional diversity of the Moon's interior. Basalt fragments from the lunar regolith can potentially sample lava flows from regions of the Moon not previously visited, thus, increasing our understanding of lunar geological evolution. As part of a study of basaltic diversity at the Apollo 12 landing site, detailed petrological and geochemical data are provided here for 13 basaltic chips. In addition to bulk chemistry, we have analyzed the major, minor, and trace element chemistry of mineral phases which highlight differences between basalt groups. Where samples contain olivine, the equilibrium parent melt magnesium number (Mg#; atomic Mg/[Mg + Fe]) can be calculated to estimate parent melt composition. Ilmenite and plagioclase chemistry can also determine differences between basalt groups. We conclude that samples of approximately 1-2 mm in size can be categorized provided that appropriate mineral phases (olivine, plagioclase, and ilmenite) are present. Where samples are fine-grained (grain size <0.3 mm), a "paired samples t-test" can provide a statistical comparison between a particular sample and known lunar basalts. Of the fragments analyzed here, three are found to belong to each of the previously identified olivine and ilmenite basalt suites, four to the pigeonite basalt suite, one is an olivine cumulate, and two could not be categorized because of their coarse grain sizes and lack of appropriate mineral phases. Our approach introduces methods that can be used to investigate small sample sizes (i.e., fines) from future sample return missions to investigate lava flow diversity and petrological significance.

  1. The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

    OpenAIRE

    Hongying Dong; Wanlin Cao; Jianhui Bian; Jianwei Zhang

    2014-01-01

    In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were...

  2. Impact Behavior of Recycled Aggregate Concrete Based on Split Hopkinson Pressure Bar Tests

    OpenAIRE

    Yubin Lu; Xing Chen; Xiao Teng; Shu Zhang

    2013-01-01

    This paper presents the experimental results of recycled aggregate concrete (RAC) specimens prepared with five different amounts of recycled coarse aggregate (RCA) (i.e., 0, 25%, 50%, 75%, and 100%) subjected to impact loading based on split Hopkinson pressure bar tests. Strain-rate effects on dynamic compressive strength and critical strain of RAC were studied. Results show that the impact properties of RAC exhibit strong strain-rate dependency and increase approximately linearly with strain...

  3. Virtual Screening for Dipeptide Aggregation: Toward Predictive Tools for Peptide Self-Assembly

    OpenAIRE

    Frederix, Pim W. J. M.; Ulijn, Rein V.; Hunt, Neil T.; Tuttle, Tell

    2011-01-01

    Several short peptide sequences are known to self-assemble into supramolecular nanostructures with interesting properties. In this study, coarse-grained molecular dynamics is employed to rapidly screen all 400 dipeptide combinations and predict their ability to aggregate as a potential precursor to their self-assembly. The simulation protocol and scoring method proposed allows a rapid determination of whether a given peptide sequence is likely to aggregate (an indicator for the ability to sel...

  4. FOAM CONCRETE REINFORCEMENT BY BASALT FIBRES

    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich

    2012-10-01

    Full Text Available The authors demonstrate that the foam concrete performance can be improved by dispersed reinforcement, including methods that involve basalt fibres. They address the results of the foam concrete modeling technology and assess the importance of technology-related parameters. Reinforcement efficiency criteria are also provided in the article. Dispersed reinforcement improves the plasticity of the concrete mix and reduces the settlement crack formation rate. Conventional reinforcement that involves metal laths and rods demonstrates its limited application in the production of concrete used for thermal insulation and structural purposes. Dispersed reinforcement is preferable. This technology contemplates the infusion of fibres into porous mixes. Metal, polymeric, basalt and glass fibres are used as reinforcing components. It has been identified that products reinforced by polypropylene fibres demonstrate substantial abradability and deformability rates even under the influence of minor tensile stresses due to the low adhesion strength of polypropylene in the cement matrix. The objective of the research was to develop the type of polypropylene of D500 grade that would demonstrate the operating properties similar to those of Hebel and Ytong polypropylenes. Dispersed reinforcement was performed by the basalt fibre. This project contemplates an autoclave-free technology to optimize the consumption of electricity. Dispersed reinforcement is aimed at the reduction of the block settlement in the course of hardening at early stages of their operation, the improvement of their strength and other operating properties. Reduction in the humidity rate of the mix is based on the plasticizing properties of fibres, as well as the application of the dry mineralization method. Selection of optimal parameters of the process-related technology was performed with the help of G-BAT-2011 Software, developed at Moscow State University of Civil Engineering. The authors also

  5. Quantifying glassy and crystalline basalt partitioning in the oceanic crust

    Science.gov (United States)

    Moore, Rachael; Ménez, Bénédicte

    2016-04-01

    The upper layers of the oceanic crust are predominately basaltic rock, some of which hosts microbial life. Current studies of microbial life within the ocean crust mainly focus on the sedimentary rock fraction, or those organisms found within glassy basalts while the potential habitability of crystalline basalts are poorly explored. Recently, there has been recognition that microbial life develops within fractures and grain boundaries of crystalline basalts, therefore estimations of total biomass within the oceanic crust may be largely under evaluated. A deeper understanding of the bulk composition and fractionation of rocks within the oceanic crust is required before more accurate estimations of biomass can be made. To augment our understanding of glassy and crystalline basalts within the oceanic crust we created two end-member models describing basalt fractionation: a pillow basalt with massive, or sheet, flows crust and a pillow basalt with sheeted dike crust. Using known measurements of massive flow thickness, dike thickness, chilled margin thickness, pillow lava size, and pillow lava glass thickness, we have calculated the percentage of glassy versus crystalline basalts within the oceanic crust for each model. These models aid our understanding of textural fractionation within the oceanic crust, and can be applied with bioenergetics models to better constrain deep biomass estimates.

  6. Microbial colonization and alteration of basaltic glass

    Directory of Open Access Journals (Sweden)

    J. Einen

    2006-03-01

    Full Text Available Microorganisms have been reported to be associated with the alteration of the glassy margin of seafloor pillow basalts (Thorseth et al., 2001, 2003; Lysnes et al., 2004. The amount of iron and other biological important elements present in basalts and the vast abundance of basaltic glass in the earth's crust, make glass alteration an important process in global element cycling. To gain further insight into microbial communities associated with glass alteration, five microcosm experiments mimicking seafloor conditions were inoculated with seafloor basalt and incubated for one year. Mineral precipitations, microbial attachment to the glass and glass alteration were visualized by scanning electron microscopy (SEM, and the bacterial community composition was fingerprinted by PCR and denaturing gradient gel electrophoresis (DGGE in combination with sequencing. SEM analysis revealed a microbial community with low morphological diversity of mainly biofilm associated and prosthecate microorganisms. Approximately 30 nm thick alteration rims developed on the glass in all microcosms after one year of incubation; this however was also seen in non inoculated controls. Calcium carbonate precipitates showed parallel, columnar and filamentous crystallization habits in the microcosms as well as in the sterile controls. DGGE analysis showed an alteration in bacterial community profiles in the five different microcosms, as a response to the different energy and redox regimes and time. In all microcosms a reduction in number of DGGE bands, in combination with an increase in cell abundance were recorded during the experiment. Sequence analysis showed that the microcosms were dominated by four groups of organisms with phylogenetic affiliation to four taxa: The Rhodospirillaceae, a family containing phototrophic marine organisms, in which some members are capable of heterotrophic growth in darkness and N2 fixation; the family Hyphomicrobiaceae, a group

  7. Aggregates from mineral wastes

    Directory of Open Access Journals (Sweden)

    Baic Ireneusz

    2016-01-01

    Full Text Available The problem concerning the growing demand for natural aggregates and the need to limit costs, including transportation from remote deposits, cause the increase in growth of interest in aggregates from mineral wastes as well as in technologies of their production and recovery. The paper presents the issue related to the group of aggregates other than natural. A common name is proposed for such material: “alternative aggregates”. The name seems to be fully justified due to adequacy of this term because of this raw materials origin and role, in comparison to the meaning of natural aggregates based on gravel and sand as well as crushed stones. The paper presents characteristics of the market and basic application of aggregates produced from mineral wastes, generated in the mining, power and metallurgical industries as well as material from demolished objects.

  8. A NEW OLIGO-MIOCENE MAMMAL-BEARING SITE FROM A SEDIMENTARY INTERCALATION IN THE TRAP BASALTS OF CENTRAL ERITREA.

    Directory of Open Access Journals (Sweden)

    ERNESTO ABBATE

    2012-11-01

    Full Text Available We report the findings of two proboscideans from a sedimentary intercalation within the Central Eritrea Tertiary Trap basalt succession. These intertrappean sediments can be traced continuously between Tera’emni and Adi Quala in the Mendefera region, and are interbedded between the underlying Asmara/Aiba-Alaji basalts and the overlying Adi Ugri basalt. This intercalation is up to 50 m thick and consists of a predominant intensely pedogenized red, green and gray mudstone and siltstone with subordinate channelized pebbly sandstone. The newly discovered mammal remains come from the coarse-grained deposits in the Mai Gobro section.  Available radiometric datings of the host volcanic rocks constrain the age of the fossils between 24.6 and 22.1 Ma, i.e. at the transition between the Oligocene and the Miocene. The fossil vertebrate remains from Mai Gobro represent two proboscidean families, Deinotheriidae and Gomphotheriidae. The morphological grade of the two Mai Gobro proboscideans would suggest a more derived stage than that of representatives of the same families known from other Oligocene African sited (e.g. Chilga, Ethiopia, suggesting a possible Oligo-Miocene age. 

  9. East Mariana Basin tholeiites: Cretaceous intraplate basalts or rift basalts related to the Ontong Java plume?

    Science.gov (United States)

    Castillo, P.R.; Pringle, M.S.; Carlson, R.W.

    1994-01-01

    Studies of seafloor magnetic anomaly patterns suggest the presence of Jurassic oceanic crust in a large area in the western Pacific that includes the East Mariana, Nauru and Pigafetta Basins. Sampling of the igneous crust in this area by the Deep Sea Drilling Program (DSDP) and the Ocean Drilling Program (ODP) allows direct evaluation of the age and petrogenesis of this crust. ODP Leg 129 drilled a 51 m sequence of basalt pillows and massive flows in the central East Mariana Basin. 40Ar 39Ar ages determined in this study for two Leg 129 basalts average 114.6 ?? 3.2 Ma. This age is in agreement with the Albian-late Aptian paleontologic age of the overlying sediments, but is distinctively younger than the Jurassic age predicted by magnetic anomaly patterns in the basin. Compositionally, the East Mariana Basin basalts are uniformly low-K tholeiites that are depleted in highly incompatible elements compared to moderately incompatible ones, which is typical of mid-ocean ridge basalts (MORB) erupted near hotspots. The Sr, Nd and Pb isotopic compositions of the tholeiites ( 87Sr 86Srinit = 0.70360-0.70374; 143Nd 144Ndinit = 0.512769-0.512790; 206Pb 204Pbmeas = 18.355-18.386) also overlap with some Indian Ocean Ridge MORB, although they are distinct from the isotopic compositions of Jurassic basalts drilled in the Pigafetta Basin, the oldest Pacific MORB. The isotopic compositions of the East Mariana Basin tholeiites are also similar to those of intraplate basalts, and in particular, to the isotopic signature of basalts from the nearby Ontong Java and Manihiki Plateaus. The East Mariana Basin tholeiites also share many petrologic and isotopic characteristics with the oceanic basement drilled in the Nauru Basin at DSDP Site 462. In addition, the new 110.8 ?? 1.0 Ma 40Ar 39Ar age for two flows from the bottom of Site 462 in the Nauru Basin is indistinguishable from the age of the East Mariana Basin flows. Thus, while magnetic anomaly patterns predict that the igneous

  10. Comparative environmental assessment of natural and recycled aggregate concrete.

    Science.gov (United States)

    Marinković, S; Radonjanin, V; Malešev, M; Ignjatović, I

    2010-11-01

    Constant and rapid increase in construction and demolition (C&D) waste generation and consumption of natural aggregate for concrete production became one of the biggest environmental problems in the construction industry. Recycling of C&D waste represents one way to convert a waste product into a resource but the environment benefits through energy consumption, emissions and fallouts reductions are not certain. The main purpose of this study is to determine the potentials of recycled aggregate concrete (concrete made with recycled concrete aggregate) for structural applications and to compare the environmental impact of the production of two types of ready-mixed concrete: natural aggregate concrete (NAC) made entirely with river aggregate and recycled aggregate concrete (RAC) made with natural fine and recycled coarse aggregate. Based on the analysis of up-to-date experimental evidence, including own tests results, it is concluded that utilization of RAC for low-to-middle strength structural concrete and non-aggressive exposure conditions is technically feasible. The Life Cycle Assessment (LCA) is performed for raw material extraction and material production part of the concrete life cycle including transport. Assessment is based on local LCI data and on typical conditions in Serbia. Results of this specific case study show that impacts of aggregate and cement production phases are slightly larger for RAC than for NAC but the total environmental impacts depend on the natural and recycled aggregates transport distances and on transport types. Limit natural aggregate transport distances above which the environmental impacts of RAC can be equal or even lower than the impacts of NAC are calculated for the specific case study. PMID:20434898

  11. Crystal Stratigraphy of Two Basalts from Apollo 16: Unique Crystallization of Picritic Basalt 606063,10-16 and Very-Low-Titanium Basalt 65703,9-13

    Science.gov (United States)

    Donohue, P. H.; Neal, C. R.; Stevens, R. E.; Zeigler, R. A.

    2014-01-01

    A geochemical survey of Apollo 16 regolith fragments found five basaltic samples from among hundreds of 2-4 mm regolith fragments of the Apollo 16 site. These included a high-Ti vitrophyric basalt (60603,10-16) and one very-low-titanium (VLT) crystalline basalt (65703,9-13). Apollo 16 was the only highlands sample return mission distant from the maria (approx. 200 km). Identification of basaltic samples at the site not from the ancient regolith breccia indicates input of material via lateral transport by post-basin impacts. The presence of basaltic rocklets and glass at the site is not unprecedented and is required to satisfy mass-balance constraints of regolith compositions. However, preliminary characterization of olivine and plagioclase crystal size distributions indicated the sample textures were distinct from other known mare basalts, and instead had affinities to impact melt textures. Impact melt textures can appear qualitatively similar to pristine basalts, and quantitative analysis is required to distinguish between the two in thin section. The crystal stratigraphy method is a powerful tool in studying of igneous systems, utilizing geochemical analyses across minerals and textural analyses of phases. In particular, trace element signatures can aid in determining the ultimate origin of these samples and variations document subtle changes occurring during their petrogenesis.

  12. Crushed aggregates for roads and their properties for frost protection

    Science.gov (United States)

    Kuznetsova, Elena; Willy Danielsen, Svein

    2015-04-01

    of the road system. According to new specification; the size of large stones for this layer should be maximum 0.5 m (longest edge) or ½ layer thickness. And minimum 30% of stones should be less than 90 mm. Fines content (material less than 22.4 mm. Analysing these new requirements, several questions are arising. First of all how this materials size will affect heat exchange in the layer, secondly - if the allowable fines content will make the materials frost susceptible. For calculations of frost protection layer thickness the knowledge of thermal conductivity of the aggregate layers is required. Handbook for geotechnical investigations of the soils provides this data for natural gravel which is limited by 0.7 - 1.3 W/mK. But when it comes to the crushed rocks, it can be significantly increased due to the higher conductivity of minerals (especially if they contain high amount of quartz), as well as due to higher effective conductivity. In rock-fill materials, i.e. materials with large particles and low degree of saturation, convection and radiation are the predominant heat transfer mechanisms. Convection and radiation can increase the effective conductivity by factor 2-10. Lebeau and Konrad (2007) showed that convection heat transfer could lead to the formation of undesirable permafrost conditions in toe drains of embankment dams located in Northern Quebec, i.e. in areas where there are no naturally occurring permafrost soils. In a frost design method the required parameter values of crushed rock aggregates are thermal conductivity, density and water content. The heat transfer during the freezing of natural soils is assumed proportional to thermal conductivity of the material. In a coarse-grained material with abundant pore space, convective heat transfer and radiation may be a considerable factor, sometimes even more significant than conduction. Specifications used by pavement engineers in most countries are solely based on grain size distribution and allowable

  13. Application of Base Force Element Method to Mesomechanics Analysis for Recycled Aggregate Concrete

    Directory of Open Access Journals (Sweden)

    Yijiang Peng

    2013-01-01

    Full Text Available The base force element method (BFEM on potential energy principle is used to analyze recycled aggregate concrete (RAC on mesolevel. The model of BFEM with triangular element is derived. The recycled aggregate concrete is taken as five-phase composites consisting of natural coarse aggregate, new mortar, new interfacial transition zone (ITZ, old mortar, and old ITZ on meso-level. The random aggregate model is used to simulate the mesostructure of recycled aggregate concrete. The mechanics properties of uniaxial compression and tension tests for RAC are simulated using the BFEM, respectively. The simulation results agree with the test results. This research method is a new way for investigating fracture mechanism and numerical simulation of mechanics properties for recycled aggregate concrete.

  14. Airborne Measurements of Coarse Mode Aerosol Composition and Abundance

    Science.gov (United States)

    Froyd, K. D.; Murphy, D. M.; Brock, C. A.; Ziemba, L. D.; Anderson, B. E.; Wilson, J. C.

    2015-12-01

    Coarse aerosol particles impact the earth's radiative balance by direct scattering and absorption of light and by promoting cloud formation. Modeling studies suggest that coarse mode mineral dust and sea salt aerosol are the dominant contributors to aerosol optical depth throughout much of the globe. Lab and field studies indicate that larger aerosol particles tend to be more efficient ice nuclei, and recent airborne measurements confirm the dominant role of mineral dust on cirrus cloud formation. However, our ability to simulate coarse mode particle abundance in large scale models is limited by a lack of validating measurements above the earth's surface. We present airborne measurements of coarse mode aerosol abundance and composition over several mid-latitude, sub-tropical, and tropical regions from the boundary layer to the stratosphere. In the free troposphere the coarse mode constitutes 10-50% of the total particulate mass over a wide range of environments. Above North America mineral dust typically dominates the coarse mode, but biomass burning particles and sea salt also contribute. In remote environments coarse mode aerosol mainly consists of internally mixed sulfate-organic particles. Both continental and marine convection can enhance coarse aerosol mass through direct lofting of primary particles and by secondary accumulation of aerosol material through cloud processing.

  15. A STDY ON EFFECT OF SIZE OF AGGREGATE ON COMPRESSIVE STRENGHT OF CONCRETE AND STRENGHT CHARACTERSTICS BY UTILIZATIION OF WASTE MATERIALS AS COURSE AGGREGATE IN CONCRETE

    Directory of Open Access Journals (Sweden)

    SETTIUBATHULA RAMYA

    2015-05-01

    Full Text Available Depletion of natural resources is a common phenomenon in developing countries like India due to rapid urbanization and Industrialization involving construction of Infrastructure and other amenities. In view of this, searching for suitable other viable alternative materials for concrete so that the existing natural resources could be preserved to the possible extent, for the future generation. To investigate the effect of size of aggregate on the compressive strength of concrete an experimental program was carried out. Four different sizes of coarse aggregates were used while developing the mix design. The sizes of coarse aggregate were 25mm, 20mm, 10mm and 4.75mm. Natural sand with fineness modules of 3.48 was used as fine aggregate. Ordinary Portland cement of 43 Grade was used as binding material. Different trials of mixing of coarse aggregate were made (25 mm and 20mm, 20mm and 10mm, 10mm and 4.75mm to investigate the influence of size of aggregate on compressive strength of concrete. Cubes of size 150mmx150mmx150mm were cast in laboratory and tested in Compression Testing Machine. It was concluded that 10mm and 4.75mm aggregates showed higher compressive strength than other types of aggregates. The tests revealed that on the replacement of 20% of ceramic tiles had increased the compressive strength of 13% more than that of conventional concrete. And it was observed that optimum ceramic tiles content was 20%. It is observed that by using 10% of plastic waste in concrete ,the fatigue characteristics of modified concrete has increased than that of plain cement concrete

  16. A coarse-grained spectral signature generator

    Science.gov (United States)

    Lam, K. P.; Austin, J. C.; Day, C. R.

    2007-01-01

    This paper investigates the method for object fingerprinting in the context of element specific x-ray imaging. In particular, the use of spectral descriptors that are illumination invariant and viewpoint independent for pattern identification was examined in some detail. To improve generating the relevant "signature", the spectral descriptor constructed is enhanced with a differentiator which has built-in noise filtration capability and good localisation properties, thus facilitating the extraction of element specific features at a coarse-grained level. In addition to the demonstrable efficacy in identifying significant image intensity transitions that are associated with the underlying physical process of interest, the method has the distinct advantage of being conceptually simple and computationally efficient. These latter properties allow the descriptor to be further utilised by an intelligent system capable of performing a fine-grained analysis of the extracted pattern signatures. The performance of the spectral descriptor has been studied in terms of the quality of the signature vectors that it generated, quantitatively based on the established framework of Spectral Information Measure (SIM). Early results suggested that such a multiscale approach of image sequence analysis offers a considerable potential for real-time applications.

  17. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten;

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...... by tissue factor evaluated by means of impedance aggregometry. Citrated whole blood from healthy volunteers and haemophilia A patients with the addition of inhibitors of the contact pathway and fibrin polymerization was evaluated. In healthy persons, a second wave of platelet aggregation was found...

  18. Buchert coarse-graining and the classical energy conditions

    CERN Document Server

    Visser, Matt

    2015-01-01

    So-called "Buchert averaging" is actually a coarse-graining procedure, where fine detail is "smeared out" due to limited spatio-temporal resolution. For technical reasons, (to be explained herein), "averaging" is not really an appropriate term, and I shall consistently describe the process as a "coarse-graining". Because Einstein gravity is nonlinear the coarse-grained Einstein tensor is typically not equal to the Einstein tensor of the coarse-grained spacetime geometry. The discrepancy can be viewed as an "effective" stress-energy, and this "effective" stress-energy often violates the classical energy conditions. To keep otherwise messy technical issues firmly under control, I shall work with conformal-FLRW (CFLRW) cosmologies. These CFLRW-based models are particularly tractable, and are also particularly attractive observationally: the CMB is not distorted. In this CFLRW context one can prove some rigorous theorems regarding the interplay between Buchert coarse-graining, tracelessness of the effective stres...

  19. Aggregated Computational Toxicology Online Resource

    Data.gov (United States)

    U.S. Environmental Protection Agency — Aggregated Computational Toxicology Online Resource (AcTOR) is EPA's online aggregator of all the public sources of chemical toxicity data. ACToR aggregates data...

  20. ASSIMILATION OF COARSE-SCALEDATAUSINGTHE ENSEMBLE KALMAN FILTER

    KAUST Repository

    Efendiev, Yalchin

    2011-01-01

    Reservoir data is usually scale dependent and exhibits multiscale features. In this paper we use the ensemble Kalman filter (EnKF) to integrate data at different spatial scales for estimating reservoir fine-scale characteristics. Relationships between the various scales is modeled via upscaling techniques. We propose two versions of the EnKF to assimilate the multiscale data, (i) where all the data are assimilated together and (ii) the data are assimilated sequentially in batches. Ensemble members obtained after assimilating one set of data are used as a prior to assimilate the next set of data. Both of these versions are easily implementable with any other upscaling which links the fine to the coarse scales. The numerical results with different methods are presented in a twin experiment setup using a two-dimensional, two-phase (oil and water) flow model. Results are shown with coarse-scale permeability and coarse-scale saturation data. They indicate that additional data provides better fine-scale estimates and fractional flow predictions. We observed that the two versions of the EnKF differed in their estimates when coarse-scale permeability is provided, whereas their results are similar when coarse-scale saturation is used. This behavior is thought to be due to the nonlinearity of the upscaling operator in the case of the former data. We also tested our procedures with various precisions of the coarse-scale data to account for the inexact relationship between the fine and coarse scale data. As expected, the results show that higher precision in the coarse-scale data yielded improved estimates. With better coarse-scale modeling and inversion techniques as more data at multiple coarse scales is made available, the proposed modification to the EnKF could be relevant in future studies.

  1. High Modulus Asphalt Concrete with Dolomite Aggregates

    Science.gov (United States)

    Haritonovs, V.; Tihonovs, J.; Smirnovs, J.

    2015-11-01

    Dolomite is one of the most widely available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1,000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality, mainly, its LA index (The Los Angeles abrasion test). Therefore, mostly the imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used, which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue, and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance with EN 13108-1 standard.

  2. Het Zevengebergte als supergroeve. Drachenfels, Stenzelberger, Wolkenburger en basalt

    NARCIS (Netherlands)

    Nijland, T.G.

    2015-01-01

    Vanuit Nederlands perspectief kan het Zevengebergte aan de Rijn tegenover Bonn als één grote groeve worden beschouwd. In de middeleeuwen leverde het gebied de bekende Drachenfels trachiet. In de 19e eeuw stichten Nederlanders de Basalt AG in Linz om aan de grote vraag naar basalt voor waterbouwkundi

  3. On Linear Relationships between Trace Elements in Oceanic Basalts

    Institute of Scientific and Technical Information of China (English)

    万渝生

    1991-01-01

    On the basis of the batch melting model*,the author explains the linear relationships between the elements which are often recognized in oceanic basalts,has established mathematic models,discusses some relevant questions,and finally gives an example to show how to apply the method to research on basalts.

  4. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    Pleistocene times. These basalts mark the end of a period of shallow subduction of the Nazca slab beneath the Payenia province and volcanism in the Nevado volcanic field apparently followed the downwarping slab in a north-northwest direction ending in the Northern Segment. The northern Payenia basalts...

  5. Vesicularity of basalt erupted at Reykjanes Ridge crest

    Science.gov (United States)

    Duffield, W.A.

    1978-01-01

    Average vesicularity of basalt drilled at three sites on the west flank of the Reykjanes Ridge increases with decreasing age. This change apparently records concomitant decrease in water depth at the ridge crest where the basalt was erupted and suggests substantial upward growth of the crest during the past 35 Myr. ?? 1978 Nature Publishing Group.

  6. Hydrothermal interaction of a ceramic waste form with basalt

    International Nuclear Information System (INIS)

    The behavior of crystalline supercalcine-ceramic in the presence of basalt was investigated under mild hydrothermal conditions at 100, 200, and 3000C with a pressure of 300 bars. Both the solid phases and solution concentrations of the interaction products of basalt and supercalcine-ceramic were characterized. At 1000C, no alteration products could be detected in experiments involving supercalcine-ceramic and basalt. The solution analyses for elements specific to the supercalcine-ceramic did not indicate any significant differences between the treatments with and without basalt, suggesting little or no interaction between basalt and supercalcine-ceramic at this temperature. At 3000C, several solid alteration/interaction products were identified. These products included two phases, pollucite and scheelite, originally incorporated into the ceramic formulation but which reformed with different bulk chemical compositions. In addition, isolated crystals of unidentified K (+-Ba) aluminosilicate phases were observed. Solution analyses of these runs did not indicate any significant differences between the treatments of supercalcine-ceramic with and without basalt, except that the Sr concentration decreased in the presence of basalt. Similar behavior was noted earlier, when basalt and SrZrO3 experiments were conducted. Alteration products and solution concentrations at 2000C lie intermediate between the 1000 and 3000C results

  7. Hydrogeology of the basalts in the Uruguayan NW

    International Nuclear Information System (INIS)

    This work is about the hydrogeological aspects in the NW Uruguayan basaltic area. The results of this research are the main geological, morphological and hydrogeological aspects of the area as well as the characteristics and the color of the basalt and sandstones

  8. Protein Colloidal Aggregation Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J. (Compiler)

    2014-01-01

    To investigate the pathways and kinetics of protein aggregation to allow accurate predictive modeling of the process and evaluation of potential inhibitors to prevalent diseases including cataract formation, chronic traumatic encephalopathy, Alzheimer's Disease, Parkinson's Disease and others.

  9. [Determination of Total Iron and Fe2+ in Basalt].

    Science.gov (United States)

    Liu, Jian-xun; Chen, Mei-rong; Jian, Zheng-guo; Wu, Gang; Wu, Zhi-shen

    2015-08-01

    Basalt is the raw material of basalt fiber. The content of FeO and Fe2O3 has a great impact on the properties of basalt fibers. ICP-OES and dichromate method were used to test total Fe and Fe(2+) in basalt. Suitable instrument parameters and analysis lines of Fe were chosen for ICP-OES. The relative standard deviation (RSD) of ICP-OES is 2.2%, and the recovery is in the range of 98%~101%. The method shows simple, rapid and highly accurate for determination of total Fe and Fe(2+) in basalt. The RSD of ICP-OES and dichromate method is 0.42% and 1.4%, respectively.

  10. Origin of High-Alumina Basalt, Andesite, and Dacite Magmas.

    Science.gov (United States)

    Hamilton, W

    1964-10-30

    The typical volcanic rocks of most island arcs and eugeosynclines, and of some continental environments, are basalt, andesite, and dacite, of high alumina content. The high-alumina basalt differs from tholeiitic basalt primarily in having a greater content of the components of calcic plagioclase. Laboratory data indicate that in the upper mantle, below the level at which the basaltic component of mantle rock is transformed by pressure to eclogite or pyroxenite, the entire basaltic portion probably is melted within a narrow temperature range, but that above the level of that transformation plagioclase is melted selectively before pyroxene over a wide temperature range. The broad spectrum of high-alumina magmas may represent widely varying degrees of partial melting above the transformation level, whereas narrow-spectrum tholeiite magma may represent more complete melting beneath it.

  11. Control of oxidation potential for basalt repository simulation tests

    International Nuclear Information System (INIS)

    Borosilicate waste glass durability in simulated repository environments can be assessed by use of static tests in leach vessels fabricated of the representative geomedia. Control of the oxidation potential during the test simulates a basalt repository environment. Under very anoxic conditions (i.e. at negative Eh values), the interactions between basalt and SRP waste glass in silica-saturated basaltic groundwaters are the same as those of basalt and groundwater when no waste glass is present. The lack of significant leaching of ions from the waste glass and the lack of any significant changes in either the leached surfaces of glass or basalt under anoxic conditions suggests that the components of this system are at equilibrium when oxygen is absent. 11 refs., 4 figs

  12. Contrasting Sr isotope ratios in plagioclase from different formations of the mid-Miocene Columbia River Basalt Group

    Science.gov (United States)

    Starkel, W. A.; Wolff, J.; Eckberg, A.; Ramos, F.

    2008-12-01

    Many early Columbia River Basalt flows of the Steens and Imnaha Formations are characterized by abundant, texturally complex, coarse plagioclase phenocrysts. In Imnaha lavas, the feldspars typically have more radiogenic 87Sr/86Sr than whole rock and matrix, and may exhibit complex isotopic zoning that is not correlated with An content. Imnaha plagioclase grains are interpreted as variably-contaminated crystals produced when high-crystallinity mid-crustal basaltic intrusions exchanged interstitial melt with adjacent partly-melted crustal rock; this isotopically variable debris was then remobilized by subsequent intrusion of mantle-derived basalt and brought to the surface as an isotopically heterogeneous mixture. In contrast, plagioclase grains in the texturally very similar Steens lavas are isotopically near-homogeneous and 87Sr/86Sr is not significantly displaced from that of the bulk rock. This is consistent with magma- crust interaction at low degrees of crustal melting during the early stages of the Columbia River flood basalt episode, where Steens and Imnaha lavas were erupted from distinct magma systems hosted by different types of crust that exerted different degrees of isotopic leverage on the mantle-derived magmas [1]. Thermal input to the Steens system declined at the same time as the Imnaha magmatic flux increased to ultimately produce the huge outpouring of Grande Ronde lavas, which are mixtures of mantle- and crust-derived liquids, the latter produced during high degrees of crustal melting during the time of peak magmatic flux. [1] Wolff et al. (2008) Nature Geoscience 1, 177-180.

  13. Cell aggregation and sedimentation.

    Science.gov (United States)

    Davis, R H

    1995-01-01

    The aggregation of cells into clumps or flocs has been exploited for decades in such applications as biological wastewater treatment, beer brewing, antibiotic fermentation, and enhanced sedimentation to aid in cell recovery or retention. More recent research has included the use of cell aggregation and sedimentation to selectively separate subpopulations of cells. Potential biotechnological applications include overcoming contamination, maintaining plasmid-bearing cells in continuous fermentors, and selectively removing nonviable hybridoma cells from perfusion cultures.

  14. Decompression-Induced Crystallization of Hydrous Basalt

    Science.gov (United States)

    Teasdale, R.; Brooker, R. A.

    2014-12-01

    Decompression-induced crystallization of hydrous basalt during magma ascent from 1.5 kb (150 MPa) is quantified using isothermal decompression TZM experiments. The starting composition is a synthetic glass based on the 1921 Kilauea basalt, with 1% H2O added. In all cases, the liquidus phase is aluminous spinel, followed by clinopyroxene, then plagioclase. The plagioclase liquidus temperatures for isobaric (equilibrium) experiments range from 1175°C (at 1.5 kb) to 1217°C (at 200b), which are 35-75°C hotter than predicted by MELTS (Ghiorso & Sack 1995). Experiments were decompressed at 1kb/hr and quenched at 800, 400, 200, or 100b for three temperatures (1160°, 1150°, and 1140°C). Plagioclase crystals formed during decompression have long axes that range from less than 1 micron to 20 microns. Increasing decompression yields larger plagioclase crystal sizes and aspect ratios for experiments at equal temperatures. However, the number of crystals does not vary systematically, indicating that crystallization is dominated by growth rather than nucleation during decompression. Plagioclase compositions for experiments were measured with University of Bristol's Electron Microprobe and the Hyperprobe with Field Emission Gun. Plagioclase compositions from equilibrium experiments (An60-An80) span the range of those from decompression experiments (An60-An73). Equilibrium experiments generated higher An compositions at lower pressures (500b) than at higher pressure (1.5kb) but do not systematically vary with temperature. Variations in plagioclase compositions are minimal above H2O saturation (100-200°C, based on Papale et al., 2006). Below H2O saturation, An content decreases slightly, by approximately 4% An. One application of this work is better characterization of groundmass crystallization in hydrous basalt as it traverses the conduit during eruption. This work also provides a means of distinguishing groundmass plagioclase related to decompression from crystals

  15. Heavy minerals in basalt maares and diatremes of South-Slovak alkali basaltic volcanic field

    International Nuclear Information System (INIS)

    A heavy mineral is one with a density that is greater than 2.8 g/cm3. Heavy mineral suites are usually used for determination of provenance and history of sedimentary and metamorphic rocks. The present study is focused on heavy minerals from pyroclastic rocks collected in maars and diatremes from the South Slovakian alkali basalt volcanic field. Practical part describes sampling strategy and methods of heavy mineral separation. Heavy minerals association from maar Hodejov and Filakovo as well as from diatremes Surice and Tachty were studied. The results indicates, that the samples are suitable for further research like geochronology, definition of possible heavy minerals source rocks and sedimentology analyses. This work will help us to get new information about alkali basalt volcanism in Southern Slovakia. (author)

  16. Molecular Approaches to Understand Nutritional Potential of Coarse Cereals.

    Science.gov (United States)

    Singh, Amit Kumar; Singh, Rakesh; Subramani, Rajkumar; Kumar, Rajesh; Wankhede, Dhammaprakash P

    2016-06-01

    Coarse grains are important group of crops that constitutes staple food for large population residing primarily in the arid and semi-arid regions of the world. Coarse grains are designated as nutri-cereals as they are rich in essential amino acids, minerals and vitamins. In spite of having several nutritional virtues in coarse grain as mentioned above, there is still scope for improvement in quality parameters such as cooking qualities, modulation of nutritional constituents and reduction or elimination of anti-nutritional factors. Besides its use in traditional cooking, coarse grains have been used mainly in the weaning food preparation and other malted food production. Improvement in quality parameters will certainly increase consumer's preference for coarse grains and increase their demand. The overall genetic gain in quality traits of economic importance in the cultivated varieties will enhance their industrial value and simultaneously increase income of farmers growing these varieties. The urgent step for improvement of quality traits in coarse grains requires a detailed understanding of molecular mechanisms responsible for varied level of different nutritional contents in different genotypes of these crops. In this review we have discussed the progresses made in understanding of coarse grain biology with various omics tool coupled with modern breeding approaches and the current status with regard to our effort towards dissecting traits related to improvement of quality and nutritional constituents of grains. PMID:27252585

  17. Non-Galerkin Coarse Grids for Algebraic Multigrid

    Energy Technology Data Exchange (ETDEWEB)

    Falgout, Robert D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Schroder, Jacob B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-06-26

    Algebraic multigrid (AMG) is a popular and effective solver for systems of linear equations that arise from discretized partial differential equations. And while AMG has been effectively implemented on large scale parallel machines, challenges remain, especially when moving to exascale. Particularly, stencil sizes (the number of nonzeros in a row) tend to increase further down in the coarse grid hierarchy, and this growth leads to more communication. Therefore, as problem size increases and the number of levels in the hierarchy grows, the overall efficiency of the parallel AMG method decreases, sometimes dramatically. This growth in stencil size is due to the standard Galerkin coarse grid operator, $P^T A P$, where $P$ is the prolongation (i.e., interpolation) operator. For example, the coarse grid stencil size for a simple three-dimensional (3D) seven-point finite differencing approximation to diffusion can increase into the thousands on present day machines, causing an associated increase in communication costs. We therefore consider algebraically truncating coarse grid stencils to obtain a non-Galerkin coarse grid. First, the sparsity pattern of the non-Galerkin coarse grid is determined by employing a heuristic minimal “safe” pattern together with strength-of-connection ideas. Second, the nonzero entries are determined by collapsing the stencils in the Galerkin operator using traditional AMG techniques. The result is a reduction in coarse grid stencil size, overall operator complexity, and parallel AMG solve phase times.

  18. INCIPIENT MOTION OF COARSE PARTICLES IN HIGH GRADIENT RIVERS

    Institute of Scientific and Technical Information of China (English)

    Shengfa YANG; Jiang HU; Xingkui WANG

    2006-01-01

    In Northwest China, there are many inland rivers that are characterized by high a gradient, coarse particles, a thick pebble and gravel layer, and small discharge and shallow water depth during the flood season. In these rivers, the motion of coarse particles has an important influence on the construction of various structures related to these rivers. In this study, the law of the motion of coarse particles is investigated in high gradient rivers. First, according to the rolling mode of particle motion, the forces acting on coarse particles were analyzed, and a formula was deduced to represent the incipient drag force for uniform coarse particles in a high gradient river. The flow velocity near the river bed, resistance coefficient, and weight of a coarse particle were taken into account to obtain the formula, which indicated that the incipient drag force is not related to the sediment Reynolds number, but closely related to the Froude number, which was also true for the Maxwell formula. Next, after comparing the various criteria for incipient motion of sediment, experiments were done to obtain data and determine the incipient motion of coarse particles. Based on the experiments, it was concluded that the motion type of "embedded" coarse material belongs to the motion of contact load, and the nondimensional unit-width sediment transport rate, which was put forward by Taylor in 1971, was chosen as the criterion in this study. Finally, based on the experimental data, the drag force formula was calibrated. The computed drag force agreed well with the measured values. Moreover, the formula derived in this study was compared with the Maxwell formula, another formula to study the incipient motion of particles in step-shaped mountainous rivers. The comparison indicates that the slope is the key factor in the two formulas, and the weight is an important force on the incipient motion of coarse particles in the current formula, but not in the Maxwell formula.

  19. Shrinkage cracking of lightweight concrete made with cold-bonded fly ash aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Mehmet Gesoglu; Turan Ozturan; Erhan Guneyisi [Bogazici University, Istanbul (Turkey). Department of Civil Engineering

    2004-07-01

    Shrinkage cracking performance of lightweight concrete (LWC) has been investigated experimentally on ring-type specimens. LWCs with and without silica fume were produced at water-cementitious material ratios (w/cm) of 0.32 to 0.55 with cold-bonded fly ash coarse aggregates and natural sand. Coarse aggregate volume ratios were 30%, 45%, and 60% of the total aggregate volume in the mixtures. A total of 12 lightweight aggregate concrete mixtures was cast and tested for compressive strength, static elastic modulus, split-tensile strength, free shrinkage, weight loss, creep, and restrained shrinkage. It was found that the crack opening on ring specimens was wider than 2 mm for all concretes. Free shrinkage, weight loss, and maximum crack width increased, while compressive and split-tensile strengths, static elastic modulus, and specific creep decreased with increasing coarse aggregate content. The use of silica fume improved the mechanical properties but negatively affected the shrinkage performance of LWCs. Shrinkage cracking performance of LWCs was significantly poorer than normal weight concrete (NWC).

  20. Study on lithogeochemistry of Middle Jurassic basalts from southern China represented by the Fankeng basalts from Yongding of Fujian Province

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jincheng; JIANG Shaoyong; WANG Xiaolei; YANG Jinghong; ZHANG Mengqun

    2006-01-01

    There exists an E-W trending Middle Jurassic volcanic zone in southern China. The Fankeng basalts in the Yongding basin of Fujian Province are considered to be a typical example. The Fankeng basalts have TiO2 contents in the range of 1.92%-3.21%. They are classified as high-Ti basalts. They also have higher total Fe (averaging FeO*= 11.09%). The Middle Jurassic Fankeng basalts from southwestern Fujian have obvious distinctive lithogeochemical features from early Cretaceous basalts from southeastern coast of China. They have higher HFSE, such as Th, Nb, Ta, Zr and Ti. Their element ratios related with HFSE, such as Zr/Ba, La/Nb, La/Ta ,Zr/Y, Ti/Y, Ba/Nb, K/Ti and Rb/Zr are similar to those of OIB. The most samples have εNd(T) of -0.70-0.24, which are near chondrite. Some samples have higher εNd(T) of 1.87-3.55.Therefore, these basaltic magmas might be derived from depleted asthenospheric mantle. The lithogeochemical characteristics of the Fankeng basalts may be caused by interaction between asthenosphere and lithosphere at the time. The (Early-)Middle Jurassic basalts and gabbros from southeastern Hunan, southern Jiangxi and northern Guangdong provinces show similar geochemical features to those of the Fankeng basalts from the Yongding of Fujian. Occurrence of these OIB-type basalts in the area may be regarded as the petrological mark of upwelling of asthenosphere at the time. Upwelling of asthenosphere has led to tectonic extension and the formation of rifted basin in the area.

  1. Studying the possibility of dehairing coarse sheep wool

    Directory of Open Access Journals (Sweden)

    Murat Otynshiyev

    2013-03-01

    Full Text Available The article considers the development of complex technology of advanced processing of coarse and medium sheep wool that enables the production of new types of woolen products such as downy fiber and from downy fiber various semi-finished and finished products. Investigations of technological processes of primary and advanced processing of untrue coarse and medium wool are carried out and wool sorting, wool washing, and obtaining downy fiber from wool on the basis of coarse wool fiber pulling on carding machines are the stages of processing the wool.

  2. Adaptive coarse graining, environment, strong decoherence, and quasiclassical realms

    Science.gov (United States)

    Gell-Mann, Murray; Hartle, James B.

    2014-05-01

    Three ideas are introduced that when brought together characterize the realistic quasiclassical realms of our quantum universe as particular kinds of sets of alternative coarse-grained histories defined by quasiclassical variables: (i) branch-dependent adaptive coarse grainings that can be close to maximally refined and can simplify calculation, (ii) narrative coarse grainings that describe how features of the universe change over time and allow the construction of an environment, and (iii) a notion of strong decoherence that characterizes realistic mechanisms of decoherence.

  3. Influence of Fly Ash, Bottom Ash, and Light Expanded Clay Aggregate on Concrete

    Directory of Open Access Journals (Sweden)

    S. Sivakumar

    2015-01-01

    Full Text Available Invention of new methods in strengthening concrete is under work for decades. Developing countries like India use the extensive reinforced construction works materials such as fly ash and bottom ash and other ingredients in RCC construction. In the construction industry, major attention has been devoted to the use of fly ash and bottom ash as cement and fine aggregate replacements. In addition, light expanded clay aggregate has been introduced instead of coarse aggregate to make concrete have light weight. This paper presents the results of a real-time work carried out to form light weight concrete made with fly ash, bottom ash, and light expanded clay aggregate as mineral admixtures. Experimental investigation on concrete mix M20 is done by replacement of cement with fly ash, fine aggregate with bottom ash, and coarse aggregate with light expanded clay aggregate at the rates of 5%, 10%, 15%, 20%, 25%, 30%, and 35% in each mix and their compressive strength and split tensile strength of concrete were discussed for 7, 28, and 56 days and flexural strength has been discussed for 7, 28, and 56 days depending on the optimum dosage of replacement in compressive strength and split tensile strength of concrete.

  4. The Aggregate Gradation for the Porous Concrete Pervious Road Base Material

    Institute of Scientific and Technical Information of China (English)

    YANG Zhifeng; MA Wei; SHEN Weiguo; ZHOU Mingkai

    2008-01-01

    The effects of the proportion of fine aggregate, the maximum size of the aggregate and the proportion of the 9.5mm to 4.75mm particle in the coarse aggregate on the properties of the porous concrete are investigated. Results indicate that the porous concrete with a cement dosage only 150kg/m3 has high strength and satisfying permeability when the aggregate has a passing percentage of 4.75mm around 10% to 5%, with the increase of the maximum size of the aggregate, the strength of the porous concrete decreases and the permeability increases. When the proportion of the 9.5mm to 4.75mm particle in the coarse aggregate is about 20%, there are no interference among the particles by Weymouth theory, the strength of the pervious porous concrete reaches the peak value. The optimum continues gradation limit of the aggregate for porous concrete pervious road base material is recommended according to the theoretical calculation and experimental results.

  5. 40Ar/39Ar impact ages and time-temperature argon diffusion history of the Bunburra Rockhole anomalous basaltic achondrite

    Science.gov (United States)

    Jourdan, Fred; Benedix, Gretchen; Eroglu, Ela.; Bland, Phil. A.; Bouvier, Audrey.

    2014-09-01

    The Bunburra Rockhole meteorite is a brecciated anomalous basaltic achondrite containing coarse-, medium- and fine-grained lithologies. Petrographic observations constrain the limited shock pressure to between ca. 10 GPa and 20 GPa. In this study, we carried out nine 40Ar/39Ar step-heating experiments on distinct single-grain fragments extracted from the coarse and fine lithologies. We obtained six plateau ages and three mini-plateau ages. These ages fall into two internally concordant populations with mean ages of 3640 ± 21 Ma (n = 7; P = 0.53) and 3544 ± 26 Ma (n = 2; P = 0.54), respectively. Based on these results, additional 40Ar/39Ar data of fusion crust fragments, argon diffusion modelling, and petrographic observations, we conclude that the principal components of the Bunburra Rockhole basaltic achondrite are from a melt rock formed at ∼3.64 Ga by a medium to large impact event. The data imply that this impact generated high enough energy to completely melt the basaltic target rock and reset the Ar systematics, but only partially reset the Pb-Pb age. We also conclude that a complete 40Ar∗ resetting of pyroxene and plagioclase at this time could not have been achieved at solid-state conditions. Comparison with a terrestrial analog (Lonar crater) shows that the time-temperature conditions required to melt basaltic target rocks upon impact are relatively easy to achieve. Ar data also suggest that a second medium-size impact event occurred on a neighbouring part of the same target rock at ∼3.54 Ga. Concordant low-temperature step ages of the nine aliquots suggest that, at ∼3.42 Ga, a third smaller impact excavated parts of the ∼3.64 Ga and ∼3.54 Ga melt rocks and brought the fragments together. The lack of significant impact activity after 3.5 Ga, as recorded by the Bunburra Rockhole suggests that (1) either the meteorite was ejected in a small secondary parent body where it resided untouched by large impacts, or (2) it was covered by a porous heat

  6. Evaluation method of cracking resistance of lightweight aggregate concrete

    Institute of Scientific and Technical Information of China (English)

    季韬; 张彬彬; 陈永波; 庄一舟

    2014-01-01

    The cracking behavior of lightweight aggregate concrete (LWAC) was investigated by mechanical analysis, SEM and cracking-resistant test where a shrinkage-restrained ring with a clapboard was used. The relationship between the ceramsite type and the cracking resistance of LWAC was built up and compared with that of normal-weight coarse aggregate concrete (NWAC). A new method was proposed to evaluate the cracking resistance of concrete, where the concepts of cracking coefficient ζt(t) and the evaluation index Acr(t) were proposed, and the development of micro-cracks and damage accumulation were recognized. For the concrete with an ascending cracking coefficient curve, the larger Acr(t) is, the lower cracking resistance of concrete is. For the concrete with a descending cracking coefficient curve, the larger Acr(t) is, the stronger the cracking resistance of concrete is. The evaluation results show that in the case of that all the three types of coarse aggregates in concrete are pre-soaked for 24 h, NWAC has the lowest cracking resistance, followed by the LWAC with lower water absorption capacity ceramsite and the LWAC with higher water absorption capacity ceramsite has the strongest cracking resistance. The proposed method has obvious advantages over the cracking age method, because it can evaluate the cracking behavior of concrete even if the concrete has not an observable crack.

  7. Non-commutativity from coarse grained classical probabilities

    CERN Document Server

    Wetterich, C

    2010-01-01

    Non-commutative quantum physics at the atom scale can arise from coarse graining of a classical statistical ensemble at the Planck scale. Position and momentum of an isolated particle are classical observables which remain computable in terms of the coarse grained information. However, the commuting classical product of position and momentum observables is no longer defined in the coarse grained system, which is therefore described by incomplete statistics. The microphysical classical statistical ensemble at the Planck scale admits an alternative non-commuting product structure for position and momentum observables which is compatible with the coarse graining. Measurement correlations for isolated atoms are based on this non-commutative product structure. We present an explicit example for these ideas. It also realizes the discreteness of the spin observable within a microphysical classical statistical ensemble.

  8. Two-level method with coarse space size independent convergence

    Energy Technology Data Exchange (ETDEWEB)

    Vanek, P.; Brezina, M. [Univ. of Colorado, Denver, CO (United States); Tezaur, R.; Krizkova, J. [UWB, Plzen (Czech Republic)

    1996-12-31

    The basic disadvantage of the standard two-level method is the strong dependence of its convergence rate on the size of the coarse-level problem. In order to obtain the optimal convergence result, one is limited to using a coarse space which is only a few times smaller than the size of the fine-level one. Consequently, the asymptotic cost of the resulting method is the same as in the case of using a coarse-level solver for the original problem. Today`s two-level domain decomposition methods typically offer an improvement by yielding a rate of convergence which depends on the ratio of fine and coarse level only polylogarithmically. However, these methods require the use of local subdomain solvers for which straightforward application of iterative methods is problematic, while the usual application of direct solvers is expensive. We suggest a method diminishing significantly these difficulties.

  9. Mineral chemistry of Pangidi basalt flows from Andhra Pradesh

    Indian Academy of Sciences (India)

    P V Nageswara Rao; P C Swaroop; Syed Karimulla

    2012-04-01

    This paper elucidates the compositional studies on clinopyroxene, plagioclase, titaniferous magnetite and ilmenite of basalts of Pangidi area to understand the geothermometry and oxybarometry conditions. Petrographic evidence and anorthite content (up to 85%) of plagioclase and temperature estimates of clinopyroxene indicate that the clinopyroxene is crystallized later than or together with plagioclase. The higher An content indicates that the parent magma is tholeiitic composition. The equilibration temperatures of clinopyroxene (1110–1190°C) and titaniferous magnetite and ilmenite coexisting mineral phases (1063–1103°C) are almost similar in lower basalt flow and it is higher for clinopyroxene (900–1110°C) when compared to titaniferous magnetite and ilmenite coexisting mineral phases (748–898°C) in middle and upper basalt flows. From this it can be inferred that the clinopyroxene is crystallized earlier than Fe–Ti oxide phases reequilibration, which indicates that the clinopyroxene temperature is the approximate eruption temperature of the present lava flows. The wide range of temperatures (900–1190°C) attained by clinopyroxene may point out that the equilibration of clinopyroxene crystals initiated from depth till closer to the surface before the melt erupted. Pangidi basalts follow the QFM buffer curve which indicates the more evolved tholeiitic composition. This suggests the parent tholeiitic magma suffered limited fractionation at high temperature under increasing oxygen fugacity in lower basalt flow and more fractionation at medium to lower temperatures under decreasing oxygen fugacity conditions during cooling of middle and upper basalt flows. The variation of oxygen fugacity indicates the oxidizing conditions for lower basalt flow (9.48–10.3) and extremely reducing conditions for middle (12.1–15.5) and upper basalt (12.4–15.54) flows prevailed at the time of cooling. Temperature vs. (FeO+Fe2O3)/(FeO+Fe2O3+MgO) data plots for present

  10. High water content in primitive continental flood basalts

    Science.gov (United States)

    Xia, Qun-Ke; Bi, Yao; Li, Pei; Tian, Wei; Wei, Xun; Chen, Han-Lin

    2016-01-01

    As the main constituent of large igneous provinces, the generation of continental flood basalts (CFB) that are characterized by huge eruption volume (>105 km3) within short time span (basaltic melts and the partition coefficient of H2O between cpx and basaltic melt. The arc-like H2O content (4.82 ± 1.00 wt.%) provides the first clear evidence that H2O plays an important role in the generation of CFB. PMID:27143196

  11. Basaltic volcanic episodes of the Yucca Mountain region

    International Nuclear Information System (INIS)

    The purpose of this paper is to summarize briefly the distribution and geologic characteristics of basaltic volcanism in the Yucca Mountain region during the last 10--12 Ma. This interval largely postdates the major period of silicic volcanism and coincides with and postdates the timing of major extensional faulting in the region. Field and geochronologic data for the basaltic rocks define two distinct episodes. The patterns in the volume and spatial distribution of these basaltic volcanic episodes in the central and southern part of the SNVF are used as a basis for forecasting potential future volcanic activity in vicinity of Yucca Mountain. 33 refs., 2 figs

  12. Pliocene Basaltic Volcanism in The East Anatolia Region (EAR), Turkey

    Science.gov (United States)

    Oyan, Vural; Özdemir, Yavuz; Keskin, Mehmet

    2016-04-01

    East Anatolia Region (EAR) is one of the high Plateau which is occurred with north-south compressional regime formed depending on continent-continent collision between Eurasia and Arabia plates (Şengör and Kidd, 1979). Recent studies have revealed that last oceanic lithosphere in the EAR have completely depleted to 20 million years ago based on fission track ages (Okay et al. 2010). Our initial studies suggest that extensively volcanic activity in the EAR peaked in the Pliocene and continued in the same productivity throughout Quaternary. Voluminous basaltic lava plateaus and basaltic lavas from local eruption centers occurred as a result of high production level of volcanism during the Pliocene time interval. In order to better understand the spatial and temporal variations in Pliocene basaltic volcanism and to reveal isotopic composition, age and petrologic evolution of the basaltic volcanism, we have started to study basaltic volcanism in the East Anatolia within the framework of a TUBITAK project (project number:113Y406). Petrologic and geochemical studies carried out on the Pliocene basaltic lavas indicate the presence of subduction component in the mantle source, changing the character of basaltic volcanism from alkaline to subalkaline and increasing the amount of spinel peridotitic melts (contributions of lithospheric mantle?) in the mantle source between 5.5-3.5 Ma. FC, AFC and EC-AFC modelings reveal that the while basaltic lavas were no or slightly influenced by crustal contamination and fractional crystallization, to more evolved lavas such as bazaltictrachyandesite, basalticandesite, trachybasalt might have been important processes. Results of our melting models and isotopic analysis data (Sr, Nd, Pb, Hf, 18O) indicate that the Pliocene basaltic rocks were derived from both shallow and deep mantle sources with different melting degrees ranging between 0.1 - 4 %. The percentage of spinel seems to have increased in the mantle source of the basaltic

  13. Sustainable Concrete with Recycled Aggregate

    OpenAIRE

    Kara, P

    2012-01-01

    Concretes produced with recycled aggregates are the subject of several papers recently published in the technical literature. Substitution of natural aggregates can be one of possibilities to take care of landfills and increase of CO2 emissions into the atmosphere in Latvia. Recycled aggregate is a valuable resource; value-added consumption of recycled aggregate, as replacement for virgin aggregate in concrete, can yield significant energy and environmental benefits. In present study recycled...

  14. Generalization of the DLA process with different immiscible components by time-scale coarse graining

    Energy Technology Data Exchange (ETDEWEB)

    Postnikov, E B [Kursk State University, Theoretical Physics Department, Radishcheva st, 33, 305000, Kursk (Russian Federation); Ryabov, A B [MV Lomonosov Moscow State University, Physics Faculty, 119992 Moscow (Russian Federation); Loskutov, A [MV Lomonosov Moscow State University, Physics Faculty, 119992 Moscow (Russian Federation)

    2007-10-05

    In the framework of the mean-field approximation we propose a new approach to the description of the growth of fractal structures which are formed as a result of the process of diffusion limited aggregation. Our approach is based on the coarse graining of the time scale which takes into account the property of discreteness of such structures. The obtained system of partial differential equations allows us to evaluate numerically the fractal dimension and the cluster density depending on the distance from the cluster center. The results are in a quite good agreement with values found by the direct numerical simulations. The proposed approach is generalized for the case of the cluster description with different immiscible particles.

  15. Generalization of the DLA process with different immiscible components by time-scale coarse graining

    Science.gov (United States)

    Postnikov, E. B.; Ryabov, A. B.; Loskutov, A.

    2007-10-01

    In the framework of the mean-field approximation we propose a new approach to the description of the growth of fractal structures which are formed as a result of the process of diffusion limited aggregation. Our approach is based on the coarse graining of the time scale which takes into account the property of discreteness of such structures. The obtained system of partial differential equations allows us to evaluate numerically the fractal dimension and the cluster density depending on the distance from the cluster center. The results are in a quite good agreement with values found by the direct numerical simulations. The proposed approach is generalized for the case of the cluster description with different immiscible particles.

  16. Conveying of Coarse-Grained Particles in Pipes

    OpenAIRE

    Vlasák, P.; Chára, Z.; Konfršt, J. (Jiří); Sobota , J.; Kysela, B. (Bohuš)

    2013-01-01

    The effect of slurry velocity and concentration on the coarse-grained particle–water mixtures flow behavior and pressure drops was studied in horizontal and inclined pipes of inner diameter 100 mm. The study revealed that the coarse-grained particle-water mixtures were significantly stratified, the particles moved principally in a layer close to the pipe invert, for higher flow velocities particle saltation becomes dominant mode of conveying. Frictional pressure drops in vertical pipe ...

  17. Mechanical and Physical Properties of Polyester Polymer Concrete Using Recycled Aggregates from Concrete Sleepers

    OpenAIRE

    Francisco Carrión; Laura Montalbán; Real, Julia I.; Teresa Real

    2014-01-01

    Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate) and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strenght, flexural strength, modulus of elasticity,...

  18. Aggregation on heterogeneous surface

    Institute of Scientific and Technical Information of China (English)

    Lu Hang-Jun; Wu Feng-Min; Fang Yun-Zhang

    2004-01-01

    Chessboard-like substrates are introduced in this paper, in order to study the diffusion-limited aggregation (DLA)and the motion of poly-atoms on heterogeneous surfaces. The effect of morphology of such substrates upon the cluster aggregation is investigated using the Monte Carlo simulation. It is found that the growth process and the cluster morphology are governed by the energetic topography of the substrates. Our simulation also indicate that the island density and the fractal dimension of the clusters depend strongly on the substrate topography and the activation energy.

  19. Energy-conserving coarse-graining of complex molecules.

    Science.gov (United States)

    Español, Pep; Serrano, Mar; Pagonabarraga, Ignacio; Zúñiga, Ignacio

    2016-05-25

    Coarse-graining (CG) of complex molecules is a method to reach time scales that would be impossible to access through brute force molecular simulations. In this paper, we formulate a coarse-grained model for complex molecules using first principles caculations that ensures energy conservation. Each molecule is described in a coarse way by a thermal blob characterized by the position and momentum of the center of mass of the molecule, together with its internal energy as an additional degree of freedom. This level of description gives rise to an entropy-based framework instead of the usual one based on the configurational free energy (i.e. potential of mean force). The resulting dynamic equations, which account for an appropriate description of heat transfer at the coarse-grained level, have the structure of the dissipative particle dynamics with energy conservation (DPDE) model but with a clear microscopic underpinning. Under suitable approximations, we provide explicit microscopic expressions for each component (entropy, mean force, friction and conductivity coefficients) appearing in the coarse-grained model. These quantities can be computed directly using MD simulations. The proposed non-isothermal coarse-grained model is thermodynamically consistent and opens up a first principles CG strategy for the study of energy transport issues that are not accessible using current isothermal models. PMID:27127809

  20. Spreading and collapse of big basaltic volcanoes

    Science.gov (United States)

    Puglisi, Giuseppe; Bonforte, Alessandro; Guglielmino, Francesco; Peltier, Aline; Poland, Michael

    2016-04-01

    Among the different types of volcanoes, basaltic ones usually form the most voluminous edifices. Because volcanoes are growing on a pre-existing landscape, the geologic and structural framework of the basement (and earlier volcanic landforms) influences the stress regime, seismicity, and volcanic activity. Conversely, the masses of these volcanoes introduce a morphological anomaly that affects neighboring areas. Growth of a volcano disturbs the tectonic framework of the region, clamps and unclamps existing faults (some of which may be reactivated by the new stress field), and deforms the substratum. A volcano's weight on its basement can trigger edifice spreading and collapse that can affect populated areas even at significant distance. Volcano instability can also be driven by slow tectonic deformation and magmatic intrusion. The manifestations of instability span a range of temporal and spatial scales, ranging from slow creep on individual faults to large earthquakes affecting a broad area. In the frame of MED-SVU project, our work aims to investigate the relation between basement setting and volcanic activity and stability at three Supersite volcanoes: Etna (Sicily, Italy), Kilauea (Island of Hawaii, USA) and Piton de la Fournaise (La Reunion Island, France). These volcanoes host frequent eruptive activity (effusive and explosive) and share common features indicating lateral spreading and collapse, yet they are characterized by different morphologies, dimensions, and tectonic frameworks. For instance, the basaltic ocean island volcanoes of Kilauea and Piton de la Fournaise are near the active ends of long hotspot chains while Mt. Etna has developed at junction along a convergent margin between the African and Eurasian plates and a passive margin separating the oceanic Ionian crust from the African continental crust. Magma supply and plate velocity also differ in the three settings, as to the sizes of the edifices and the extents of their rift zones. These

  1. Calcium Sulfate in Atacama Desert Basalt: A Possible Analog for Bright Material in Adirondack Basalt, Gusev Crater

    Science.gov (United States)

    Sutter, B.; Golden, D. C.; Amundson, R.; Chong-Diaz, G.; Ming, D. W.

    2007-01-01

    The Atacama Desert in northern Chile is one of the driest deserts on Earth (calcium sulfate (Ca-SO4) which was later confirmed by SEM/EDS analysis. This work examines the Ca-SO4 of Atacama basalt in an effort to provide insight into the possible nature of the bright material in the Adirondack basalt of Gusev Crater. The objectives of this work are to (i) discuss variations in Ca-SO4 crystal morphology in the vesicles and (ii) examine the Ca-SO4 interaction(s) with the basalt interior.

  2. A note on incipient spilitisation of central Indian basin basalts

    Digital Repository Service at National Institute of Oceanography (India)

    Karisiddaiah, S.M.; Iyer, S.D.

    Rocks dredged in the vicinity of the 79 degrees E fracture zone, in the Central Indian Basin, are sub-alkaline basalts, which are regarded as precursors to spilites. The minerals identified are mainly albitic plagioclase, augite, olivine, and less...

  3. Alteration of basaltic glasses from the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Iyer, S.D.

    Textural, mineralogical and compositional characteristics of basaltic glasses from the Central Indian Ocean show them to be altered to varying extents through their interaction with the seawater, resulting in the formation of palagonite. The major...

  4. Two new basaltic asteroids in the Outer Main Belt

    CERN Document Server

    Duffard, R

    2007-01-01

    The identification of other basaltic objects in the asteroid belt is mandatory to explain the diversity in the collection of basaltic meteorites. This diversity requires more than one differentiated parent body, a fact that is consistent with the diversity of differentiated parent bodies implied by the iron meteorites. Based on a list of previously identified candidate basaltic (V-type) asteroids, two asteroids in the outer main belt, (7472) Kumakiri and (10537) 1991 RY16, were spectroscopically observed during an observational run in Calar Alto Observatory, Spain. We confirm the V-type character of these two asteroids that, together with (1459) Magnya, become the only known traces of basaltic found in the outer main belt up to now. We also demonstrate that the searching for candidate V-type asteroids using a photometric survey, like the Sloan Digital Sky Survey, produces reliable results.

  5. Petrography and chemistry of basalts from the Carlsberg ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Iyer, S.D

    The petrography of the basalts collected in dredge hauls from the Carlsberg Ridge (3 degrees 37'N and 64 degrees 07'E) show systematic variations in their textural and mineralogical assemblages, from an outermost vitreous glassy to a holocrystalline...

  6. Basaltic glass: alteration mechanisms and analogy with nuclear waste glasses

    International Nuclear Information System (INIS)

    A synthetic basaltic glass was dissolved experimentally at 90 deg. C under static conditions in initially pure water. The basaltic glass dissolution rates measured near and far from equilibrium were compared with those of SON 68 nuclear waste glass. Experimental and literature data notably suggested that the alteration mechanisms for the two glasses are initially similar. Under steady-state concentration conditions, the alteration rate decreased of four orders of magnitude below the initial rate (r0). The same alteration rate decrease was observed for basaltic and nuclear glass. These findings tend to corroborate the analogy of the two glasses alteration kinetics. The effect of dissolved silica in solution, observed through dynamic leach tests with silicon-rich solutions, cannot account for the significant drop in the basaltic glass kinetics. Hence, a protective effect of the glass alteration film was assumed and experimentally investigated. Moreover, modeling with LIXIVER argue for a significant effect of diffusion in the alteration gel

  7. Geochemical characterization of oceanic basalts using artificial neural network

    Digital Repository Service at National Institute of Oceanography (India)

    Das, P.; Iyer, S.D.

    method is specifically needed to identify the OFB as normal (N-MORB), enriched (E-MORB) and ocean island basalts (OIB). Artificial Neural Network (ANN) technique as a supervised Learning Vector Quantisation (LVQ) is applied to identify the inherent...

  8. Diffusion in aggregated soil.

    NARCIS (Netherlands)

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consist

  9. Basalt waste isolation project institutional activities

    International Nuclear Information System (INIS)

    The Basalt Waste Isolation Project (BWIP) was established in 1976 as part of the National Waste Terminal Storage Program, and characterization studies to evaluate the Hanford Site have been ongoing since that time. In early 1983, the Nuclear Waste Policy Act (NWPA) became law and established the Office of Civilian Radioactive Waste Management, which includes the BWIP as part of that program. This paper describes the interaction process required by the NWPA and has been ongoing for the past 3 to 4 yr with the State of Washington, Yakima Indian Nation, Confederated Tribes of the Umatilla Indian Reservation, Nez Perce Tribe, other federal agencies, city and county governments, the public and news media, and many other organizations. It identifies the issues that the state and the US Department of Energy (DOE) have noted during the consultation and cooperation (C and C) process. In addition, this paper covers the site recommendation/nomination process for the first repository, including number of sites, location, and types of media being investigated. It covers the site recommendation/nomination process for the second repository, including types of media and where those investigations are being performed. Discussion covering the OCRWM program strategy, which includes documentation being prepared for site recommendation/nomination, site investigations required to determine site suitability, the licensing process for the first repository, etc., are provided

  10. Radiolytic Hydrogen Production in the Subseafloor Basaltic Aquifer.

    Science.gov (United States)

    Dzaugis, Mary E; Spivack, Arthur J; Dunlea, Ann G; Murray, Richard W; D'Hondt, Steven

    2016-01-01

    Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium ((238)U, (235)U), thorium ((232)Th) and potassium ((40)K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th, and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt) concentrations (which can vary between eruptive events) and post-emplacement alteration. However, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma) basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may support as

  11. Tensile tests of basalt FRP rebars using chemical anchorages

    OpenAIRE

    Neagoe, Catalin Andrei; Gil Espert, Lluís

    2013-01-01

    In the current report are analyzed the experimental results of initial tensile tests of Basalt FRP (BFRP) rebars provided by VSL. The investigation was conducted in the laboratory of CER LITEM. Objectives of the study: to determine the tensile strengths of 6 mm and 8 mm basalt FRP rebars, and to determine what type of test setup and anchorage system is best suited for future tensile tests of BFRP bars.

  12. Tensile tests of basalt FRP rebars using mechanical anchorages

    OpenAIRE

    Neagoe, Catalin Andrei; Gil Espert, Lluís

    2013-01-01

    In the current report are analyzed the experimental results of initial tensile tests of Basalt FRP (BFRP) rebars provided by VSL. The investigation was conducted on the 19th of February 2013, in the laboratory of CER LITEM. Objectives of the study: to determine the tensile strengths of 6 mm and 8 mm basalt FRP rebars, and to determine what type of test setup and anchorage system is best suited for future tensile tests of BFRP bars.

  13. Radiolytic hydrogen production in the subseafloor basaltic aquifer

    Directory of Open Access Journals (Sweden)

    Mary E Dzaugis

    2016-02-01

    Full Text Available Hydrogen (H2 is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium (238U, 235U, thorium (232Th and potassium (40K. To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt concentrations (which can vary between eruptive events and post-emplacement alteration. In our samples, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may

  14. Radiolytic Hydrogen Production in the Subseafloor Basaltic Aquifer

    Science.gov (United States)

    Dzaugis, Mary E.; Spivack, Arthur J.; Dunlea, Ann G.; Murray, Richard W.; D’Hondt, Steven

    2016-01-01

    Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from radioactive decay of naturally occurring uranium (238U, 235U), thorium (232Th) and potassium (40K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we use radionuclide concentrations of 43 basalt samples from IODP Expedition 329 to calculate radiolytic H2 production rates in basement fractures. The samples are from three sites with very different basement ages and a wide range of alteration types. U, Th, and K concentrations vary by up to an order of magnitude from sample to sample at each site. Comparison of our samples to each other and to the results of previous studies of unaltered East Pacific Rise basalt suggests that significant variations in radionuclide concentrations are due to differences in initial (unaltered basalt) concentrations (which can vary between eruptive events) and post-emplacement alteration. However, there is no clear relationship between alteration type and calculated radiolytic yields. Local maxima in U, Th, and K produce hotspots of H2 production, causing calculated radiolytic rates to differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production, where microfractures are hotspots for radiolytic H2 production. For example, H2 production rates normalized to water volume are 190 times higher in 1 μm wide fractures than in fractures that are 10 cm wide. To assess the importance of water radiolysis for microbial communities in subseafloor basaltic aquifers, we compare electron transfer rates from radiolysis to rates from iron oxidation in subseafloor basalt. Radiolysis appears likely to be a more important electron donor source than iron oxidation in old (>10 Ma) basement basalt. Radiolytic H2 production in the volume of water adjacent to a square cm of the most radioactive SPG basalt may support as many as

  15. Basalt: Biologic Analog Science Associated with Lava Terrains

    Science.gov (United States)

    Lim, D. S. S.; Abercromby, A.; Kobs-Nawotniak, S. E.; Kobayashi, L.; Hughes, S. S.; Chappell, S.; Bramall, N. E.; Deans, M. C.; Heldmann, J. L.; Downs, M.; Cockell, C. S.; Stevens, A. H.; Caldwell, B.; Hoffman, J.; Vadhavk, N.; Marquez, J.; Miller, M.; Squyres, S. W.; Lees, D. S.; Fong, T.; Cohen, T.; Smith, T.; Lee, G.; Frank, J.; Colaprete, A.

    2015-12-01

    This presentation will provide an overview of the BASALT (Biologic Analog Science Associated with Lava Terrains) program. BASALT research addresses Science, Science Operations, and Technology. Specifically, BASALT is focused on the investigation of terrestrial volcanic terrains and their habitability as analog environments for early and present-day Mars. Our scientific fieldwork is conducted under simulated Mars mission constraints to evaluate strategically selected concepts of operations (ConOps) and capabilities with respect to their anticipated value for the joint human and robotic exploration of Mars. a) Science: The BASALT science program is focused on understanding habitability conditions of early and present-day Mars in two relevant Mars-analog locations (the Southwest Rift Zone (SWRZ) and the East Rift Zone (ERZ) flows on the Big Island of Hawai'i and the eastern Snake River Plain (ESRP) in Idaho) to characterize and compare the physical and geochemical conditions of life in these environments and to learn how to seek, identify, and characterize life and life-related chemistry in basaltic environments representing these two epochs of martian history. b) Science Operations: The BASALT team will conduct real (non-simulated) biological and geological science at two high-fidelity Mars analogs, all within simulated Mars mission conditions (including communication latencies and bandwidth constraints) that are based on current architectural assumptions for Mars exploration missions. We will identify which human-robotic ConOps and supporting capabilities enable science return and discovery. c) Technology: BASALT will incorporate and evaluate technologies in to our field operations that are directly relevant to conducting the scientific investigations regarding life and life-related chemistry in Mars-analogous terrestrial environments. BASALT technologies include the use of mobile science platforms, extravehicular informatics, display technologies, communication

  16. High water content in primitive continental flood basalts

    Science.gov (United States)

    Xia, Qun-Ke; Bi, Yao; Li, Pei; Tian, Wei; Wei, Xun; Chen, Han-Lin

    2016-05-01

    As the main constituent of large igneous provinces, the generation of continental flood basalts (CFB) that are characterized by huge eruption volume (>105 km3) within short time span (partition coefficient of H2O between cpx and basaltic melt. The arc-like H2O content (4.82 ± 1.00 wt.%) provides the first clear evidence that H2O plays an important role in the generation of CFB.

  17. Evaluation of basalt flows as a waste isolation medium

    International Nuclear Information System (INIS)

    The Basalt Waste Isolation Program within Rockwell Hanford Operations has the responsibility of conducting studies to determine the feasibility of using the basalt formations, which are in the Pacific Northwest and the Hanford Site, as a site for terminal storage of commercial nuclear waste. This program is divided into systems integration, geology, hydrology, engineered barrier studies, engineering testing, and the construction of a near-surface test facility. Brief descriptions of each task are presented

  18. Volume calculations of coarse woody debris; evaluation of coarse woody debris volume calculations and consequences for coarse woody debris volume estimates in forest reserves

    NARCIS (Netherlands)

    Wijdeven, S.M.J.; Vaessen, O.H.B.; Hees, van A.F.M.; Olsthoorn, A.F.M.

    2005-01-01

    Dead wood is recognized as one of the key indicators for sustainable forest management and biodiversity. Accurate assessments of dead wood volume are thus necessary. In this study New volume models were designed based on actual volume measurements of coarse woody debris. The New generic model accura

  19. Insulation from basaltic stamp sand. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Williams, F. D.

    1981-04-01

    A Midwest Appropriate Technology Grant was awarded to determine the technical and economic feasibility of producing mineral-fiber insulation directly from extensive deposits of basaltic sand produced during former mining and milling operations in the Keweenaw Peninsula region of Michigan's Upper Peninsula. The amounts of local basaltic sands available and representative chemical compositions were determined. The variation of viscosity with temperature and chemical composition was estimated. Samples were melted and either pulled or blown into fiber. In all cases fiber could be made with a reasonable tensile strength to ensure usefulness. It was concluded that it was technically feasible to produce fibers from basaltic stamp sands of the Upper Peninsula of Michigan. A technical feasibility study using published data, a cost and design analysis of a basalt fiber production plant, a market survey of fiber needs, and an economic analysis for investing in a basalt fiber venture was undertaken. These studies concluded that the local production of basaltic insulation was both feasible and economically reasonable. It was suggested that the plant be located in a region of greater population density with lower utility costs. A representative one-third of these studies is included as appendices A, B, C, and D.

  20. Geochemical characterization of oceanic basalts using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Iyer Sridhar D

    2009-12-01

    Full Text Available Abstract The geochemical discriminate diagrams help to distinguish the volcanics recovered from different tectonic settings but these diagrams tend to group the ocean floor basalts (OFB under one class i.e., as mid-oceanic ridge basalts (MORB. Hence, a method is specifically needed to identify the OFB as normal (N-MORB, enriched (E-MORB and ocean island basalts (OIB. We have applied Artificial Neural Network (ANN technique as a supervised Learning Vector Quantisation (LVQ to identify the inherent geochemical signatures present in the Central Indian Ocean Basin (CIOB basalts. A range of N-MORB, E-MORB and OIB dataset was used for training and testing of the network. Although the identification of the characters as N-MORB, E-MORB and OIB is completely dependent upon the training data set for the LVQ, but to a significant extent this method is found to be successful in identifying the characters within the CIOB basalts. The study helped to geochemically delineate the CIOB basalts as N-MORB with perceptible imprints of E-MORB and OIB characteristics in the form of moderately enriched rare earth and incompatible elements. Apart from the fact that the magmatic processes are difficult to be deciphered, the architecture performs satisfactorily.

  1. Sensitivity of geochemical monitoring for CO2 sequestration in basalt

    Science.gov (United States)

    Zakharova, N. V.; Goldberg, D.; Herron, M.; Grau, J.

    2010-12-01

    Continental flood basalts is a promising target for carbon dioxide (CO2) storage due to high storage capacity, presence of seals, and potential for geochemical trapping which results in binding CO2 into stable carbonate minerals. The success of long-term CO2 storage in igneous rocks highly depends on our ability to monitor mineralization under in situ conditions. The direct chemistry measurements on cores are costly and typically do not provide continuous coverage. In this study we investigate the potential of borehole geochemical logging for monitoring of CO2 mineralization in basalt. Neutron-induced capture gamma ray spectroscopy tools allow obtaining in-situ concentration logs for up to 10 major elements which can be used to construct a quantitative mineralogical model. While this usually provides good bulk mineralogy estimates, detecting small-volume mineral alteration in volcanic rocks remains challenging, especially if borehole conditions are poor. We analyze Schlumberger Elemental Capture Spectroscopy logs and chemical core analysis from the pilot CO2 sequestration project in the Columbia River flood basalt. We use the geochemical spectroscopy logs and quantitative modeling to quantify their sensitivity to secondary mineralization in basalt. We apply statistical analysis to explain the variance in elemental concentrations (and other logs) and establish detection limits for various mineral alteration products in basalt. We use these results to evaluate monitoring capabilities and limitations of geochemical logging for CO2 mineralization after underground injection in basalt and suggest areas for future research.

  2. A basalt trigger for the 1991 eruptions of Pinatubo volcano?

    Science.gov (United States)

    Pallister, J.S.; Hoblitt, R.P.; Reyes, A.G.

    1992-01-01

    THE eruptive products of calc-alkaline volcanos often show evidence for the mixing of basaltic and acid magmas before eruption (see, for example, refs 1, 2). These observations have led to the suggestion3 that the injection of basaltic magma into the base of a magma chamber (or the catastrophic overturn of a stably stratified chamber containing basaltic magma at its base) might trigger an eruption. Here we report evidence for the mixing of basaltic and dacitic magmas shortly before the paroxysmal eruptions of Pinatubo volcano on 15 June 1991. Andesitic scoriae erupted on 12 June contain minerals and glass with disequilibrium compositions, and are considerably more mafic than the dacitic pumices erupted on 15 June. Differences in crystal abundance and glass composition among the pumices may arise from pre-heating of the dacite magma by the underlying basaltic liquid before mixing. Degassing of this basaltic magma may also have contributed to the climatologically important sulphur dioxide emissions that accompanied the Pinatubo eruptions.

  3. The Distribution of Basaltic Asteroids in the Main Belt

    CERN Document Server

    Moskovitz, Nicholas A; Gaidos, Eric; Willman, Mark; Nesvorny, David; Fevig, Ronald; Ivezic, Zeljko

    2008-01-01

    We present the observational results of a survey designed to target and detect asteroids whose colors are similar to those of Vesta family members and thus may be considered as candidates for having a basaltic composition. Fifty basaltic candidates were selected with orbital elements that lie outside of the Vesta dynamical family. Optical and near-infrared spectra were used to assign a taxonomic type to 11 of the 50 candidates. Ten of these were spectroscopically confirmed as V-type asteroids, suggesting that most of the candidates are basaltic and can be used to constrain the distribution of basaltic material in the Main Belt. Using our catalog of V-type candidates and the success rate of the survey, we calculate unbiased size-frequency and semi-major axis distributions of V-type asteroids. These distributions, in addition to an estimate for the total mass of basaltic material, suggest that Vesta was the predominant contributor to the basaltic asteroid inventory of the Main Belt, however scattered planetesim...

  4. Water content of primitive low-K tholeiitic basalt magma from Iwate Volcano, NE Japan arc: implications for differentiation mechanism of frontal-arc basalt magmas

    Science.gov (United States)

    Kuritani, Takeshi; Yoshida, Takeyoshi; Kimura, Jun-Ichi; Hirahara, Yuka; Takahashi, Toshiro

    2014-02-01

    The water content of low-K tholeiitic basalt magma from Iwate volcano, which is located on the volcanic front of the NE Japan arc, was estimated using multi-component thermodynamic models. The Iwate lavas are moderately porphyritic, consisting of ~8 vol.% olivine and ~20 vol.% plagioclase phenocrysts. The olivine and plagioclase phenocrysts show significant compositional variations, and the Mg# of olivine phenocrysts (Mg#78-85) correlates positively with the An content of coexisting plagioclase phenocrysts (An85-92). The olivine phenocrysts with Mg# > ~82 do not form crystal aggregates with plagioclase phenocrysts. It is inferred from these observations that the phenocrysts with variable compositions were primarily derived from mushy boundary layers along the walls of a magma chamber. By using thermodynamic calculations with the observed petrological features of the lavas, the water content of the Iwate magma was estimated to be 4-5 wt.%. The high water content of the magma supports the recent consensus that frontal-arc magmas are remarkably hydrous. Using the estimated water content of the Iwate magma, the water content and temperature of the source mantle were estimated. Given that the Iwate magma was derived from a primary magma solely by olivine fractionation, the water content and temperature were estimated to be ~0.7 wt.% and ~1,310 °C, respectively. Differentiation mechanisms of low-K frontal-arc basalt magmas were also examined by application of a thermodynamics-based mass balance model to the Iwate magma. It is suggested that magmatic differentiation proceeds primarily through fractionation of crystals from the main molten part of a magma chamber when it is located at ~200 MPa.

  5. Estimates of olivine-basaltic melt electrical conductivity using a digital rock physics approach

    Science.gov (United States)

    Miller, Kevin J.; Montési, Laurent G. J.; Zhu, Wen-lu

    2015-12-01

    Estimates of melt content beneath fast-spreading mid-ocean ridges inferred from magnetotelluric tomography (MT) vary between 0.01 and 0.10. Much of this variation may stem from a lack of understanding of how the grain-scale melt geometry influences the bulk electrical conductivity of a partially molten rock, especially at low melt fraction. We compute bulk electrical conductivity of olivine-basalt aggregates over 0.02 to 0.20 melt fraction by simulating electric current in experimentally obtained partially molten geometries. Olivine-basalt aggregates were synthesized by hot-pressing San Carlos olivine and high-alumina basalt in a solid-medium piston-cylinder apparatus. Run conditions for experimental charges were 1.5 GPa and 1350 °C. Upon completion, charges were quenched and cored. Samples were imaged using synchrotron X-ray micro-computed tomography (μ-CT). The resulting high-resolution, 3-dimensional (3-D) image of the melt distribution constitutes a digital rock sample, on which numerical simulations were conducted to estimate material properties. To compute bulk electrical conductivity, we simulated a direct current measurement by solving the current continuity equation, assuming electrical conductivities for olivine and melt. An application of Ohm's Law yields the bulk electrical conductivity of the partially molten region. The bulk electrical conductivity values for nominally dry materials follow a power-law relationship σbulk = Cσmeltϕm with fit parameters m = 1.3 ± 0.3 and C = 0.66 ± 0.06. Laminar fluid flow simulations were conducted on the same partially molten geometries to obtain permeability, and the respective pathways for electrical current and fluid flow over the same melt geometry were compared. Our results indicate that the pathways for flow fluid are different from those for electric current. Electrical tortuosity is lower than fluid flow tortuosity. The simulation results are compared to existing experimental data, and the potential

  6. Influence of replacement rate of recycled coarse aggretrate on mechanical properties of recycled concrete%再生粗骨料替代率对再生混凝土力学性能影响

    Institute of Scientific and Technical Information of China (English)

    姚宇峰; 金宝宏; 章海刚; 兰宏伟

    2016-01-01

    为研究19~26.5 mm粒径范围内的再生粗骨料等质量替代同粒径范围内天然粗骨料的再生混凝土的力学性能影响,采用再生粗骨料替代率为0~100%等质量替代天然粗骨料拌制了11种C30混凝土,对不同替代率下的新拌混凝土进行了抗压和劈裂拉伸试验。结果表明:再生混凝土的抗压、劈裂拉伸破坏形态与普通混凝土基本一致。当再生粗骨料替代率分别为60%和0时,再生混凝土的抗压强度与劈裂拉伸强度分别达到最大。研究结果可为再生粗骨料应用于混凝土中提供指导和借鉴。%To study the influence of replacement rate of recycle coarse aggregate with the size of 19~26. 5 mm on the mechanical properties of recycle concrete when the natural coarse aggregate was re-placed by the recycle coarse aggregate with the same quality, 11 kinds of C30 recycled coarse aggre-gate concrete specimens, the replacement rate of which ranged from 0 to 100%, were subjected to compression and splitting tensile tests. Results showed that the failure modes of the recycle concrete and concrete made of natural coarse aggregate are almost the same. In particular, when the replace-ment rates of recycle coarse aggregate were 60% and 0 , the compressive strength and splitting ten-sile strength reached the maximum respectively, which could provide guidance and reference for the application of recycled coarse aggregate.

  7. Basaltic Lava Flow vs. Welded Basaltic Ignimbrite: Determining the Depositional Nature of a Volcanic Flow in the Akaroa Volcanic Complex

    Science.gov (United States)

    Sexton, E. A.; Hampton, S.

    2014-12-01

    Welded basaltic ignimbrites are one of the rarest forms of ignimbrites found on Earth and can often have characteristics that are indistinguishable from those of basaltic lava flows. This study evaluates a basaltic volcanic flow in a coastal cliff sequence in Raupo Bay, Akaroa Volcanic Complex, Banks Peninsula, New Zealand. The Raupo Bay coastal cliff sequence is comprised of 4 units, termed L1, L2, L3, and A, capped by loess. L1 and L2 are basaltic lavas, L3 proximal scoria deposits, which thin inland, and Unit A, a flow with unusual characteristics, which is the focus of this study. Field mapping, sampling, geochemical analysis and petrology were utilized to characterize units. Further detailed structural analysis of Unit A was completed, to determine the nature of the basal contact, variations in welding throughout the unit and the relationship of the layer to the underlying topography. From these analyses it was found: Unit A is thickest in a paleo-valley and thins and mantles higher topography, welding in the unit increases downwards forming topographic controlled columnar jointing, the top of the unit is brecciated and grades into the lower welded/jointed portion, the basal contact is sharp overlying a regional airfall deposit, the unit has a notably distinct geochemical composition from the underlying stratigraphic units, Unit A contains flattened and sheared scoria clasts, has aligned bubbles, and lava lithics. Further thin section analysis of Unit A identified flattened clast boundaries and microlite rimming around phenocrysts. In comparing these features to previous studies on basaltic lavas and ignimbrites it is hypothesized that Unit A is a welded basaltic ignimbrite that was channelized by paleo-topography on the outer flanks of the Akaroa Volcanic Complex. This study furthers the characterization of basaltic ignimbrites and is the first to recognize basaltic ignimbrites within the Akaroa Volcanic Complex.

  8. Properties of concrete blocks prepared with low grade recycled aggregates.

    Science.gov (United States)

    Poon, Chi-Sun; Kou, Shi-cong; Wan, Hui-wen; Etxeberria, Miren

    2009-08-01

    Low grade recycled aggregates obtained from a construction waste sorting facility were tested to assess the feasibility of using these in the production of concrete blocks. The characteristics of the sorted construction waste are significantly different from that of crushed concrete rubbles that are mostly derived from demolition waste streams. This is due to the presence of higher percentages of non-concrete components (e.g. >10% soil, brick, tiles etc.) in the sorted construction waste. In the study reported in this paper, three series of concrete block mixtures were prepared by using the low grade recycled aggregates to replace (i) natural coarse granite (10mm), and (ii) 0, 25, 50, 75 and 100% replacement levels of crushed stone fine (crushed natural granite concrete blocks. Test results on properties such as density, compressive strength, transverse strength and drying shrinkage as well as strength reduction after exposure to 800 degrees C are presented below. The results show that the soil content in the recycled fine aggregate was an important factor in affecting the properties of the blocks produced and the mechanical strength deceased with increasing low grade recycled fine aggregate content. But the higher soil content in the recycled aggregates reduced the reduction of compressive strength of the blocks after exposure to high temperature due probably to the formation of a new crystalline phase. The results show that the low grade recycled aggregates obtained from the construction waste sorting facility has potential to be used as aggregates for making non-structural pre-cast concrete blocks. PMID:19398196

  9. Long-term deflection and flexural behavior of reinforced concrete beams with recycled aggregate

    International Nuclear Information System (INIS)

    Highlights: • Long-term deformation of recycled aggregate concrete beams was examined. • Three beams were monitored for over 380 days. • Influence of recycled aggregate on the long-term performance. • Comparison of that between normal and recycled aggregate concrete beams. - Abstract: This paper presents experimental results on the long-term deformations of recycled aggregate concrete (RAC) beams for over 1 year (380 days) and flexural behavior of RAC beams after exposure to sustained loading. Three reinforced concrete (RC) beam specimens were fabricated with replacement percentage of aggregate (100% natural aggregate, 100% recycled coarse aggregate, and 50% recycled fine aggregate) and subjected to sustained loading that is 50% of the nominal flexural capacity. During the sustained loading period (380 days), the long-term deflection due to creep and shrinkage was recorded and compared with predicted behavior that was determined based on current specifications (ACI 318 Code). After measuring the long-term deflection for 380 days, four-point bending tests were conducted to investigate the flexural behavior of RC beams after exposure to sustained loading and determine any reduction in flexural capacity. A modified equation to predict the long-term deflection values for RC beams with recycled aggregate is proposed, and the experimental results are compared with the predictions calculated using the ACI 318 Code provisions

  10. NONLINEAR MULTIGRID SOLVER EXPLOITING AMGe COARSE SPACES WITH APPROXIMATION PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Max La Cour [Technical Univ. of Denmark, Lyngby (Denmark); Villa, Umberto E. [Univ. of Texas, Austin, TX (United States); Engsig-Karup, Allan P. [Technical Univ. of Denmark, Lyngby (Denmark); Vassilevski, Panayot S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-01-22

    The paper introduces a nonlinear multigrid solver for mixed nite element discretizations based on the Full Approximation Scheme (FAS) and element-based Algebraic Multigrid (AMGe). The main motivation to use FAS for unstruc- tured problems is the guaranteed approximation property of the AMGe coarse spaces that were developed recently at Lawrence Livermore National Laboratory. These give the ability to derive stable and accurate coarse nonlinear discretization problems. The previous attempts (including ones with the original AMGe method, [5, 11]), were less successful due to lack of such good approximation properties of the coarse spaces. With coarse spaces with approximation properties, our FAS approach on un- structured meshes should be as powerful/successful as FAS on geometrically re ned meshes. For comparison, Newton's method and Picard iterations with an inner state-of-the-art linear solver is compared to FAS on a nonlinear saddle point problem with applications to porous media ow. It is demonstrated that FAS is faster than Newton's method and Picard iterations for the experiments considered here. Due to the guaranteed approximation properties of our AMGe, the coarse spaces are very accurate, providing a solver with the potential for mesh-independent convergence on general unstructured meshes.

  11. Coarse particles and respiratory emergency department visits in California.

    Science.gov (United States)

    Malig, Brian J; Green, Shelley; Basu, Rupa; Broadwin, Rachel

    2013-07-01

    Although respiratory disease has been strongly connected to fine particulate air pollution (particulate matter effects of coarse particles (particulate matter from 2.5 to 10 μm in diameter), possibly because of the greater spatial heterogeneity of coarse particles. In this study, we evaluated the relationship between coarse particles and respiratory emergency department visits, including common subdiagnoses, from 2005 to 2008 in 35 California counties. A time-stratified case-crossover design was used to help control for time-invariant confounders and seasonal influences, and the study population was limited to those residing within 20 km of pollution monitors to mitigate the influence of spatial heterogeneity. Significant associations between respiratory emergency department visits and coarse particle levels were observed. Asthma visits showed associations (for 2-day lag, excess risk per 10 μg/m³ = 3.3%, 95% confidence interval: 2.0, 4.6) that were robust to adjustment by other common air pollutants (particles acute respiratory infection visits were not associated, although some suggestion of a relationship with chronic obstructive pulmonary disease visits was present. Our results indicate that coarse particle exposure may trigger asthma exacerbations requiring emergency care, and reducing exposures among asthmatic persons may provide benefits.

  12. Exploring energy landscapes of protein folding and aggregation.

    Science.gov (United States)

    Mousseau, Normand; Derreumaux, Philippe

    2008-05-01

    Human diseases, such as Alzheimer's and Creutzfeldt-Jakob's are associated with misfolding and aggregation of specific proteins into amyloid fibrils sharing a generic cross-beta structure. The self-assembly process is complex, but once a nucleus is formed, rapid fibril formation occurs. Insight into the structures of the oligomers during the lag phase, varying between hours and days, is very difficult experimentally because these species are transient, and numerically using all-atom molecular dynamics because the time scale explored is on the order of 10-100 ns. It is therefore important to develop simplified protein models and alternative methods to sample more efficiently the conformational space. In the past few years, we have developed the activation-relaxation technique (ART nouveau) coupled to the OPEP coarse-grained force field. This review reports the application of ART-OPEP on protein folding and aggregation.

  13. Vapor segregation and loss in basaltic melts

    Science.gov (United States)

    Edmonds, M.; Gerlach, T.M.

    2007-01-01

    Measurements of volcanic gases at Pu'u'O??'o??, Kilauea Volcano, Hawai'i, reveal distinct degassing regimes with respect to vapor segregation and loss during effusive activity in 2004-2005. Three styles of vapor loss are distinguished by the chemical character of the emitted volcanic gases, measured by open path Fourier transform infrared spectroscopy: 1 persistent continuous gas emission, 2 gas piston events, and 3 lava spattering. Persistent continuous gas emission is associated with magma ascent and degassing beneath the crater vents, then eruption of the degassed magma from flank vents. Gas piston events are the result of static gas accumulation at depths of 400-900 m beneath Pu'u'O??'o??. A CO2-rich gas slug travels up the conduit at a few meters per second, displacing magma as it expands. Lava spattering occurs due to dynamic bubble coalescence in a column of relatively stagnant magma. The Large gas bubbles are H2O rich and are generated by open-system degassing at depths of segregation in basaltic melts, but their implications differ. Accumulation and segregation of CO2-rich vapor at depth does not deplete the melt of H2O (required to drive lava fountains near to the surface) and therefore gas piston events can occur interspersed with lava fountaining activity. Lava spattering, however, efficiently strips H2O-rich vapor from magma beneath the crater vents; the magma must then erupt effusively from vents on the flank of the cone. ?? 2007 The Geological Society of America.

  14. Basalt Waste Isolation Project Reclamation Support Project:

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, C.A.; Rickard, W.H. Jr.; Cadoret, N.A.

    1992-06-01

    The Basalt Waste Isolation Project (BWIP) Reclamation Support Project began in the spring of 1988 by categorizing sites distributed during operations of the BWIP into those requiring revegetation and those to be abandoned or transferred to other programs. The Pacific Northwest Laboratory's role in this project was to develop plans for reestablishing native vegetation on the first category of sites, to monitor the implementation of these plans, to evaluate the effectiveness of these efforts, and to identify remediation methods where necessary. The Reclamation Support Project focused on three major areas: geologic hydrologic boreholes, the Exploratory Shaft Facility (ESF), and the Near-Surface Test Facility (NSTF). A number of BWIP reclamation sites seeded between 1989 and 1990 were found to be far below reclamation objectives. These sites were remediated in 1991 using various seedbed treatments designed to rectify problems with water-holding capacity, herbicide activity, surficial crust formation, and nutrient imbalances. Remediation was conducted during November and early December 1991. Sites were examined on a monthly basis thereafter to evaluate plant growth responses to these treatments. At all remediation sites early plant growth responses to these treatments. At all remediation sites, early plant growth far exceeded any previously obtained using other methods and seedbed treatments. Seeded plants did best where amendments consisted of soil-plus-compost or fertilizer-only. Vegetation growth on Gable Mountain was less than that found on other areas nearby, but this difference is attributed primarily to the site's altitude and north-facing orientation.

  15. A transferable coarse-grained model for diphenylalanine: How to represent an environment driven conformational transition

    International Nuclear Information System (INIS)

    One of the major challenges in the development of coarse grained (CG) simulation models that aim at biomolecular structure formation processes is the correct representation of an environment-driven conformational change, for example, a folding/unfolding event upon interaction with an interface or upon aggregation. In the present study, we investigate this transferability challenge for a CG model using the example of diphenylalanine. This dipeptide displays a transition from a trans-like to a cis-like conformation upon aggregation as well as upon transfer from bulk water to the cyclohexane/water interface. Here, we show that one can construct a single CG model that can reproduce both the bulk and interface conformational behavior and the segregation between hydrophobic/hydrophilic medium. While the general strategy to obtain nonbonded interactions in the present CG model is to reproduce solvation free energies of small molecules representing the CG beads in the respective solvents, the success of the model strongly depends on nontrivial decisions one has to make to capture the delicate balance between the bonded and nonbonded interactions. In particular, we found that the peptide's conformational behavior is qualitatively affected by the cyclohexane/water interaction potential, an interaction that does not directly involve the peptide at all but merely influences the properties of the hydrophobic/hydrophilic interface. Furthermore, we show that a small modification to improve the structural/conformational properties of the CG model could dramatically alter the thermodynamic properties

  16. A transferable coarse-grained model for diphenylalanine: How to represent an environment driven conformational transition

    Energy Technology Data Exchange (ETDEWEB)

    Dalgicdir, Cahit; Sensoy, Ozge; Sayar, Mehmet, E-mail: msayar@ku.edu.tr [College of Engineering, Koç University, 34450 Istanbul (Turkey); Peter, Christine [Max Planck Institute for Polymer Research, 55128 Mainz (Germany); Department of Chemistry, University of Konstanz, 78547 Konstanz (Germany)

    2013-12-21

    One of the major challenges in the development of coarse grained (CG) simulation models that aim at biomolecular structure formation processes is the correct representation of an environment-driven conformational change, for example, a folding/unfolding event upon interaction with an interface or upon aggregation. In the present study, we investigate this transferability challenge for a CG model using the example of diphenylalanine. This dipeptide displays a transition from a trans-like to a cis-like conformation upon aggregation as well as upon transfer from bulk water to the cyclohexane/water interface. Here, we show that one can construct a single CG model that can reproduce both the bulk and interface conformational behavior and the segregation between hydrophobic/hydrophilic medium. While the general strategy to obtain nonbonded interactions in the present CG model is to reproduce solvation free energies of small molecules representing the CG beads in the respective solvents, the success of the model strongly depends on nontrivial decisions one has to make to capture the delicate balance between the bonded and nonbonded interactions. In particular, we found that the peptide's conformational behavior is qualitatively affected by the cyclohexane/water interaction potential, an interaction that does not directly involve the peptide at all but merely influences the properties of the hydrophobic/hydrophilic interface. Furthermore, we show that a small modification to improve the structural/conformational properties of the CG model could dramatically alter the thermodynamic properties.

  17. A transferable coarse-grained model for diphenylalanine: How to represent an environment driven conformational transition

    Science.gov (United States)

    Dalgicdir, Cahit; Sensoy, Ozge; Peter, Christine; Sayar, Mehmet

    2013-12-01

    One of the major challenges in the development of coarse grained (CG) simulation models that aim at biomolecular structure formation processes is the correct representation of an environment-driven conformational change, for example, a folding/unfolding event upon interaction with an interface or upon aggregation. In the present study, we investigate this transferability challenge for a CG model using the example of diphenylalanine. This dipeptide displays a transition from a trans-like to a cis-like conformation upon aggregation as well as upon transfer from bulk water to the cyclohexane/water interface. Here, we show that one can construct a single CG model that can reproduce both the bulk and interface conformational behavior and the segregation between hydrophobic/hydrophilic medium. While the general strategy to obtain nonbonded interactions in the present CG model is to reproduce solvation free energies of small molecules representing the CG beads in the respective solvents, the success of the model strongly depends on nontrivial decisions one has to make to capture the delicate balance between the bonded and nonbonded interactions. In particular, we found that the peptide's conformational behavior is qualitatively affected by the cyclohexane/water interaction potential, an interaction that does not directly involve the peptide at all but merely influences the properties of the hydrophobic/hydrophilic interface. Furthermore, we show that a small modification to improve the structural/conformational properties of the CG model could dramatically alter the thermodynamic properties.

  18. Local Environmental Effects from Deposition of Basaltic Tephra

    Science.gov (United States)

    Ort, M. H.; Sheppard, P. R.; Anderson, K. C.; Elson, M. D.

    2012-12-01

    Basaltic tephra is produced by scoria cones and by composite and stratovolcanoes, which may cover 1000s-10,000's km2 with tephra to depths greater than 1 cm. This tephra changes the abiotic and biotic environment. The thickness of the tephra affects whether plants can send their seeds and roots to the soil underneath or grow through the tephra to reach the surface. More than 20 cm of tephra greatly inhibits most plant growth, as shown by agricultural experiments and observations of natural landscapes. At Sunset Crater in northern Arizona, incipient soil formation (after ~925 years) consists of eolian grains having sifted down to a depth of 10-20 cm, forming a finer grained layer that retains water. Plant roots concentrate at this level, helping to trap more fine grains and adding organic material to the layer. This then provides a more hospitable environment for further plant growth and the development of soil ecosystems. Fresh tephra, especially if coarse, allows water to pass through it to the underlying soil, reducing runoff, and slows subsequent evaporation. At Sunset Crater, increased water infiltration led to better plant growth in semiarid grasslands and forest and possibly to new springs and increased surface water. At Parícutin in Michoacán, México, flooding caused by abundant rain that saturated the tephra led to stream shifts and erosion. Tephra has available ions on the surface of grains and the volcanic glass may be easily altered. This, combined with increased water retention in the soil, can lead to changes in soil and groundwater chemistry underlying the tephra. Adhering sulfur, as well as HCl- and HNO3-rich rainfall, can lower pH in the water, dissolving soil ions as mineralogical phase changes occur in response to the lower pH. At three scoria cones (Sunset Crater, Paricutin, and Cinder Cone, which is in northeast California), tree-ring chemistry reflects changes in the soil-water composition. P and S increase for a few years to decades after

  19. Space-Time-Isotopic Trends of Snake River Plain Basalts

    Science.gov (United States)

    Jean, M. M.; Hanan, B. B.; Shervais, J. W.

    2010-12-01

    The Snake River Plain (SRP) volcanic province is an 800 km track of basalt extending from the Owyhee Plateau to its current terminus, the Yellowstone Plateau. It is one of several late-Tertiary magmatic terranes that also include the Cascades magmatic arc, the Columbia River basalts, and the Oregon Plateau basalts; all of which are adjacent to the Basin and Range Province extensional system (Hughes and McCurry, 2002). This province represents the track of the Yellowstone plume and consists of basalt that is compositionally similar to ocean-island basalt. This basalt overlies a series of rhyolitic eruptive centers (overlapping caldera complexes, ignimbrites, and caldera-filling eruptions) that signal the arrival of the plume head (Christiansen, 2001) and herald the onset of plume-related rhyolitic and basaltic volcanism (Pierce et al., 2002). Observed within the SRP are two basalt types: the dominant low-K olivine tholeiites and less common high-K alkaline basalts. We report new Sr-, Nd-, and Pb-isotopic analyses of these two basalt types from all three SRP provinces: eastern, central, and western. Low-K tholeiites are enriched in 143Nd/144Nd and 86Sr/87Sr and forms a quasi-linear array in Pb-isotope space, along with Craters of the Moon and eastern SRP basalts. High-K lavas are found largely in the western plain, and have a uniquely different isotopic signature. They are depleted in 143Nd/144Nd and 86Sr/87Sr, relative to the low-K tholeiites, and plot closer to the BSE component of Zindler and Hart (1986). They also share the same Pb-isotopic space with high-K basalts from Smith Prairie (Boise River Group 2 of Vetter and Shervais, 1992). One low-K tholeiite - Eureka North, plots with these high alkali basalts. Mass balance models have demonstrated an increasing plume component from the Yellowstone caldera in the east to the craton edge in the west. The lavas analyzed in this study conform remarkably to this model. The mass fraction of plume component in western

  20. Proteins aggregation and human diseases

    Science.gov (United States)

    Hu, Chin-Kun

    2015-04-01

    Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

  1. Surface oxidization-reduction reactions in Columbia Plateau basalts

    International Nuclear Information System (INIS)

    Results are presented which define principal oxidation-reduction reactions expected between ground water and iron in the Umtanum and Cohassett basalt flows of south central Washington. Data include kinetics of aqueous iron speciation, rates of O2 uptake and nature of oxyhydroxide precipitates. Such data are important in predicting behavior of radionuclides in basalt aquifers including determination of valence states, speciation, solubility, sorption, and coprecipitation on iron oxyhydroxide substrates and colloids. Analyses of the basalt by XPS indicates that ferrous iron is oxidized to ferric iron on the surface and that the total iron decreases as a function of pH during experimental weathering. Iron oxyhydroxide phases did not form surface coating on basalt surfaces but rather nucleated as separate plases in solution. No significant increases in Cs or Sr sorption were observed with increased weathering of the basalt. Concurrent increases in Fe(II) and decreases in Fe(III) in slightly to moderately acid solutions indicated continued oxidization of ferrous iron in the basalt. At neutral to basic pH, Fe(II) was strongly sorbed onto the basalt surface (Kd = 6.5 x 10-3 1 x m2) resulting in low dissolved concentrations even under anoxic conditions. The rate of O2 uptake increased with decreasing pH. Diffusion rates (-- 10-14 cm2 x s-1), calculated using a one-dimensional analytical model, indicate grain boundary diffusion. Comparisons of Eh values calculated by Pt electrode, dissolved O2 and Fe(II)/Fe(III) measurements showed considerable divergence, with the ferric-ferrous couple being the preferred method of estimating Eh

  2. Percent Coarse in wells in 15 meter increments and Texture Model Percent Coarse at Lattice Points for the Central Valley from Faunt (2009)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset contains the percentage of coarse-grained deposits in wells in 15 meter increments and the percentage of coarse-grained deposits in texture...

  3. Coarse-graining the Lin-Maldacena geometries

    International Nuclear Information System (INIS)

    The Lin-Maldacena geometries are nonsingular gravity duals to degenerate vacuum states of a family of field theories with SU(2|4) supersymmetry. In this note, we show that at large N, where the number of vacuum states is large, there is a natural 'macroscopic' description of typical states, giving rise to a set of coarse-grained geometries. For a given coarse-grained state, we can associate an entropy related to the number of underlying microstates. We find a simple formula for this entropy in terms of the data that specify the geometry. We see that this entropy function is zero for the original microstate geometries and maximized for a certain 'typical state' geometry, which we argue is the gravity dual to the zero-temperature limit of the thermal state of the corresponding field theory. Finally, we note that the coarse-grained geometries are singular if and only if the entropy function is non-zero

  4. Uplink coarse acquisition for a mobile user satellite system

    Science.gov (United States)

    Biederman, L.

    For the purpose of the present investigation, coarse time acquisition is defined as the time required to receive a successful acknowledgement from the satellite. This definition can be justified if the false alarm probability is selected to be relatively low. It is assumed that the ground platforms are mobile, the uplink signal is frequently hopped, and all users have a preassigned uplink time synchronization channel. Attention is given to acquisition algorithm and system concept, the optimum detector structure, aspects of optimum detector performance, and coarse acquisition performance tradeoffs. For the optimum choice, the detector performance is shown as a function of the number of hops accumulated by the video integrator. It is found that the coarse acquisition detector performance could be severely degraded if the uplink signal-to-noise ratio drops by more than 1 dB below the threshold requirement.

  5. Influence of Grain Size Coarse Soil on Shear Strength

    Directory of Open Access Journals (Sweden)

    Moulay smaîne Ghembaza

    2014-04-01

    Full Text Available The geo- mechanical behavior of coarse soils is difficult to grasp by geotechnical methods , mainly due to the presence of large elements that disrupt or prevent the tests . Our work presents a study of the mechanical behavior of two coarse soils of different types namely Tuff MEKKEDRA and crushed gravel SIDI ALI- Benyoub west of Algeria by observing the effect of the size of diameters of the grains on the shear strength. Two aspects are considered. The first relates to a state of the art parameters which have a direct influence on the shear strength of coarse material . The second part concerns a presentation and analysis of the results of direct shear tests of materials prepared for Optimum Proctor. It is noted that the grain size affects in a significant way the properties of the shear strength. The bigger the diameter, the greater the angle of friction is important. However, the cohesion decreases with increasing grain size.

  6. Coarse-graining two-dimensional turbulence via dynamical optimization

    CERN Document Server

    Turkington, Bruce; Thalabard, Simon

    2015-01-01

    A model reduction technique based on an optimization principle is employed to coarse-grain inviscid, incompressible fluid dynamics in two dimensions. In this reduction the spectrally-truncated vorticity equation defines the microdynamics, while the macroscopic state space consists of quasi-equilibrium trial probability densities on the microscopic phase space, which are parameterized by the means and variances of the low modes of the vorticity. A macroscopic path therefore represents a coarse-grained approximation to the evolution of a nonequilibrium ensemble of microscopic solutions. Closure in terms of the vector of resolved variables, namely, the means and variances of the low modes, is achieved by minimizing over all feasible paths the time integral of their mean-squared residual with respect to the Liouville equation. The equations governing the optimal path are deduced from Hamilton-Jacobi theory. The coarse-grained dynamics derived by this optimization technique contains a scale-dependent eddy viscosit...

  7. Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

    Science.gov (United States)

    Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

    2015-04-01

    intensity of WR in aggregates of different sizes. [ii] the intra-aggregate distribution of OC and the intensity of WR and [iii] the structural stability of soil aggregates relative to the OC content and the intensity of WR in soils under different crops (apricot, citrus and wheat) and different treatments (conventional tilling and mulching). Soil samples were collected from an experimental area (Luvic Calcisols and Calcic Luvisols) in the province of Sevilla (Southern Spain) under different crops (apricot, citrus and wheat) and different management types (conventional tillage with moldboard plow) and mulching (no-tilling and addition of wheat residues at rates varying between 5 and 8 Mg/ha/year). At each sampling site, soil blocks (50 cm long × 50 cm wide × 10 cm deep) were carefully collected to avoid disturbance of aggregates as much as possible and transported to the laboratory. At field moist condition, undisturbed soil aggregates were separated by hand. In order to avoid possible interferences due to disturbance by handling, aggregates broken during this process were discarded. Individual aggregates were arranged in paper trays and air-dried during 7 days under laboratory standard conditions. After air-drying, part of each sample was carefully divided for different analyses: [i] part of the original samples was sieved (2 mm) to eliminate coarse soil particles and homogenized for characterization of OC and N contents, C/N ratio and texture; [ii] part of the aggregates were dry-sieved (0.25-0.5, 0.5-1 and 1-2 mm) or measured with a caliper (2-5, 5-10 and 10-15 mm) and separated in different sieve-size classes for determination of WR and OC content; [iii] aggregates 10-15 mm in size were selected for obtaining aggregate layers using a soil aggregate erosion (SAE) apparatus and WR and OC content were determined at each layer; finally, [iv] in order to study the relation between stability to slaking, WR and OC, these properties were determined in 90 air-dried aggregates

  8. Discussion on “Malešev, M.; Radonjanin, V.; Marinković, S. Recycled Concrete as Aggregate for Structural Concrete Production. Sustainability, 2010, 2, 1204-1225”

    Directory of Open Access Journals (Sweden)

    Gholamreza Fathifazl

    2011-02-01

    Full Text Available The authors are to be congratulated for their comprehensive research work on the use of RCA as aggregate in structural grade concrete [1], but some of their conclusions with regard to the effect of aggregate type and RCA content on the fresh and hardened properties of concrete made with coarse RCA, termed RAC for brevity, need discussion.

  9. Basalt here, basalt there: Constraining the basaltic nature of eight Vp-type asteroids in the inner and outer main asteroid belt

    Science.gov (United States)

    Hardersen, Paul Scott; Reddy, Vishnu

    2016-10-01

    The distribution and abundance of basaltic material in the main asteroid belt has multiple implications that impact our understanding of the physical and thermal conditions that existed in the inner solar system during the formation epoch about 4.6 Gyr ago. Subjects impacted by a more accurate basaltic asteroid inventory include the efficacy of current inner solar system heating model predictions (Al-26 and T Tauri induction heating), the existence of differentiated parent bodies other than (4) Vesta, the dispersion efficiency of Vestoids by YORP forces, and the predictive ability of the V-taxonomy in predicting a basaltic surface composition. This work reports on a continuation of an effort to better constrain the basaltic asteroid population in the main asteroid belt with the goal of observing about 650 Vp-type asteroids. This work focuses on two populations: a) those Vp-classified asteroids (Carvano et al., 2010) in the spatial vicinity of (4) Vesta (candidate Vestoids) in the inner main belt, and b) Vp-classified asteroids in the outer main belt beyond 2.5 AU. Thus far, 23 Vp-type asteroids and candidate Vestoids have been observed and analyzed, which are all strongly suggestive of a basaltic surface composition (Hardersen et al., 2014, 2015, 2016 (in preparation)). However, unpublished work is beginning to show that the Vp taxonomic class is less accurate in its ability to identify basaltic surface compositions in outer-belt Vp-type asteroids. We report here on an additional set of Vp-type asteroids that were observed at the NASA Infrared Telescope Facility (IRTF) in December 2015 and January 2016. All observations were obtained with the SpeX spectrograph in prism mode with spectral range from 0.7 to 2.5 microns. They include (4900) Maymelou, (7302) 1993 CQ, (9064) Johndavies, (9531) Jean-Luc, (11341) Babbage, (17480) 1991 PE10, (20171) 1996 WC2, and (25849) 2000 ET107. We present average near-infrared (NIR) reflectance spectra of each asteroid, determine the

  10. Coarse-grained parallelism for full-core transport calculations

    International Nuclear Information System (INIS)

    In this paper we analyze the synergy between the Domain Decomposition Method and the Coarse-Mesh Finite Difference technique. In contrast to massively parallel computations, we construct a coarse-grained parallelism for daily run calculations on standard SIMD workstations based on shared memory architecture. We evaluate the effectiveness of the algorithm for several high-fidelity calculations spanning different types of color-sets up to the full-core. We show that CPU times for a best-estimate 2D calculation of the EPR can be reduced from several days to few hours using a standard workstation. (author)

  11. Coarse-grid selection for parallel algebraic multigrid

    Energy Technology Data Exchange (ETDEWEB)

    Cleary, A. J., LLNL

    1998-06-01

    The need to solve linear systems arising from problems posed on extremely large, unstructured grids has sparked great interest in parallelizing algebraic multigrid (AMG) To date, however, no parallel AMG algorithms exist We introduce a parallel algorithm for the selection of coarse-grid points, a crucial component of AMG, based on modifications of certain paallel independent set algorithms and the application of heuristics designed to insure the quality of the coarse grids A prototype serial version of the algorithm is implemented, and tests are conducted to determine its effect on multigrid convergence, and AMG complexity

  12. Effect of carbon nanotube addition on the wear behavior of basalt/epoxy woven composites.

    Science.gov (United States)

    Kim, M T; Rhee, K Y; Lee, B H; Kim, C J

    2013-08-01

    The effect of acid-treated carbon nanotube (CNT) addition on the wear and dynamic mechanical thermal properties of basalt/epoxy woven composites was investigated in this study. Basalt/CNT/epoxy composites were fabricated by impregnating woven basalt fibers into epoxy resin mixed with 1 wt% CNTs which were acid-treated. Wear and DMA (dynamic mechanical analyzer) tests were performed on basalt/epoxy composites and basalt/CNT/epoxy composites. The results showed that the addition of the acid-treated CNTs improved the wear properties of basalt/epoxy woven composites. Specifically, the friction coefficient of the basalt/epoxy composite was stabilized in the range of 0.5-0.6 while it fell in the range of 0.3-0.4 for basalt/CNT/epoxy composites. The wear volume loss of the basalt/CNT/epoxy composites was approximately 68% lower than that of the basalt/epoxy composites. The results also showed that the glass transition temperature of basalt/CNT/epoxy composites was higher than that of basalt/epoxy composites. The improvement of wear properties of basalt/epoxy composites by the addition of acid-treated CNTs was caused by the homogeneous load transfer between basalt fibers and epoxy matrix due to the reinforcement of CNTs.

  13. 再生骨料混凝土路面耐磨性的研究%Research on Abrasion Resistance of Recycled Aggregate Concrete by Response Surface Methodology

    Institute of Scientific and Technical Information of China (English)

    杨宁; 赵美霞

    2011-01-01

    采用单因素扫描法系统考察了再生粗骨料的取代率、水胶比、砂率、胶凝材料的总用量等因素对再生混凝土耐磨性能的影响,分析了其产生的原因.在单因素试验的基础上,通过响应面法对影响再生混凝土耐磨性能的显著因素进行了更进一步的研究,并建立了相应的预测模型.结果表明:再生骨料的取代率和水胶比对再生混凝土耐磨性影响最为显著,砂率和胶凝材料的总用量对再生混凝土耐磨性有一定的影响,且再生骨料取代率为43%、水胶比为0.38、砂率为35%时再生混凝土耐磨性能最佳,研究结果为再生混凝土耐磨性的深入研究提供了一定的借鉴和参考.%The single factor scanning method was used to analyze the effects of replacement ratio of recycled coarse aggregate, water-binder ratio, sand-coarse aggregate ratio, the total amount of gelled material on the wear resistance of recycled aggregate concrete, and its reasons were analyzed. On the basis of the single-factor test, the significant influence factors of the wear resistance of recycled aggregate concrete were further studied by the response surface methodology ( RSM ) , and a correlation model on the optimized wear resistance of recycled aggregate concrete was presented. The analysis results show that replacement ratio of recycled coarse aggregate, water-binder ratio exert tremendous influence on wear resistance of recycled aggregate concrete, sand-coarse aggregate ratio and the total amount of gelled material exert certain influence. Wear resistance of recycled aggregate concrete is best when replacement ratio of recycled coarse aggregate is 43% , water-binder ratio is 0. 38, sand-coarse aggregate ratio is 0. 35. The test results also can provide a reference for future further study on abrasion resistance of recycled aggregate concrete.

  14. Preliminary Hydrogeologic Characterization Results from the Wallula Basalt Pilot Study

    Energy Technology Data Exchange (ETDEWEB)

    B.P. McGrail; E. C. Sullivan; F. A. Spane; D. H. Bacon; G. Hund; P. D. Thorne; C. J. Thompson; S. P. Reidel; F. S. Colwell

    2009-12-01

    The DOE's Big Sky Regional Carbon Sequestration Partnership has completed drilling the first continental flood basalt sequestration pilot borehole to a total depth (TD) of 4,110 feet on the Boise White Paper Mill property at Wallula, Washington. Site suitability was assessed prior to drilling by the 2007-2008 acquisition, processing and analysis of a four-mile, five-line three component seismic swath, which was processed as a single data-dense line. Analysis of the seismic survey data indicated a composite basalt formation thickness of {approx}8,000 feet and absence of major geologic structures (i.e., faults) along the line imaged by the seismic swath. Drilling of Wallula pilot borehole was initiated on January 13, 2009 and reached TD on April 6, 2009. Based on characterization results obtained during drilling, three basalt breccia zones were identified between the depth interval of 2,716 and 2,910 feet, as being suitable injection reservoir for a subsequent CO2 injection pilot study. The targeted injection reservoir lies stratigraphically below the massive Umtanum Member of the Grande Ronde Basalt, whose flow-interior section possesses regionally recognized low-permeability characteristics. The identified composite injection zone reservoir provides a unique and attractive opportunity to scientifically study the reservoir behavior of three inter-connected reservoir intervals below primary and secondary caprock confining zones. Drill cuttings, wireline geophysical logs, and 31one-inch diameter rotary sidewall cores provided geologic data for characterization of rock properties. XRF analyses of selected rock samples provided geochemical characterizations of the rocks and stratigraphic control for the basalt flows encountered by the Wallula pilot borehole. Based on the geochemical results, the pilot borehole was terminated in the Wapshilla Ridge 1 flow of the Grande Ronde Basalt Formation. Detailed hydrologic test characterizations of 12 basalt interflow

  15. An ancient recipe for flood-basalt genesis.

    Science.gov (United States)

    Jackson, Matthew G; Carlson, Richard W

    2011-07-27

    Large outpourings of basaltic lava have punctuated geological time, but the mechanisms responsible for the generation of such extraordinary volumes of melt are not well known. Recent geochemical evidence suggests that an early-formed reservoir may have survived in the Earth's mantle for about 4.5 billion years (ref. 2), and melts of this reservoir contributed to the flood basalt emplaced on Baffin Island about 60 million years ago. However, the volume of this ancient mantle domain and whether it has contributed to other flood basalts is not known. Here we show that basalts from the largest volcanic event in geologic history--the Ontong Java plateau--also exhibit the isotopic and trace element signatures proposed for the early-Earth reservoir. Together with the Ontong Java plateau, we suggest that six of the largest volcanic events that erupted in the past 250 million years derive from the oldest terrestrial mantle reservoir. The association of these large volcanic events with an ancient primitive mantle source suggests that its unique geochemical characteristics--it is both hotter (it has greater abundances of the radioactive heat-producing elements) and more fertile than depleted mantle reservoirs-may strongly affect the generation of flood basalts.

  16. Stratigraphy of Oceanus Procellarum basalts - Sources and styles of emplacement

    Science.gov (United States)

    Whitford-Stark, J. L.; Head, J. W., III

    1980-01-01

    The basaltic fill of Oceanus Procellarum has been formally subdivided into four lithostratigraphic formations: The Repsold Formation, the Telemann Formation, the Hermann Formation, and the Sharp Formation. The Repsold Formation is composed of high-Ti basalts and pyroclastic deposits with an estimated age of 3.75 + or - 0.05 b.y. and an estimated volume of about 2.1 x 10 to the 5th cu km. This is overlain by the Telemann Formation composed of very low-Ti basalts and pyroclastic deposits with an estimated age of 3.6 + or - 0.2 b.y. and a volume of 4.2 x 10 to the 5th cu km. The Hermann Formation, composed of intermediate basalts with an estimated age of 3.3 + or - 0.3 b.y., represents the next youngest unit with an estimated volume of 2.2 x 10 to the 5th cu km. The youngest materials in Procellarum are the medium-to-high-Ti basalts comprising the Sharp Formation with an estimated age of 2.7 + or - 0.7 b.y. and a volume of 1.8 x 10 to the 4th cu km.

  17. Use of steel slag aggregate in asphalt concrete mixes

    Energy Technology Data Exchange (ETDEWEB)

    Asi, I.M.; Qasrawi, Y.; Shalabi, F.I. [Hashemite Univ., Zarqa (Jordan). Dept. of Civil Engineering

    2007-08-15

    The physical, chemical and mechanical properties of generated steel slag aggregates (SSA) were studied in order to investigate their potential use in asphalt concrete (AC) mixes. Five AC mixes were investigated, notably an AC mix with a 100 per cent limestone aggregate, and mixes comprised of 25, 50, 75, and 100 per cent SSA coarse aggregates. A superpave mix design was used to determine optimum asphalt content (OAC). Steps included the selection of a design aggregate structure, optimization of the asphalt content for the structure, and an evaluation of the moisture sensitivity of the design mixture. The effectiveness of the samples were assessed by their ability to improve indirect tensile strength (ITS); resilient and creep modulus; fatigue life; and stripping and rutting resistance. Various AC mixes containing the SSA were then evaluated. A gyratory compactor was used to compact the test samples, which were then subjected to comprehensive mechanical evaluations. Statistical analyses were then performed to examine the significance of the SSA percentage in the changing ITS values using analysis of variance (ANOVA) calculations. Results of the study indicated that SSA met both superpave consensus properties and Jordanian standards source properties. Chemical and toxic levels were within allowable limits. It was concluded that optimal the replacement percentage of SSA was 25 per cent. 18 refs., 9 tabs., 21 figs.

  18. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  19. Hydrophobic aggregation of ultrafine kaolinite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-ping; HU Yue-hua; LIU Run-Qing

    2008-01-01

    The hydrophobic aggregation of ultrafine kaolinite in cationic surfactant suspension was investigated by sedimentation test, zeta potential measurement and SEM observation. SEM images reveal that kaolinite particles show the self-aggregation of edge-face in acidic media, the aggregation of edge-face and edge-edge in neutral media, and the dispersion in alkaline media due to electrostatic repulsion. In the presence of the dodecylammonium acetate cationic surfactant and in neutral and alkaline suspension, the hydrophobic aggregation of face-face is demonstrated. The zeta potential of kaolinite increases with increasing the concentration of cationic surfactant. The small and loose aggregation at a low concentration but big and tight aggregation at a high concentration is presented At pH=7 alkyl quarterly amine salt CTAB has the best hydrophobic aggregation among three cationic surfactants, namely, dodecylammonium acetate, alkyl quarterly amine salts 1227 and CTAB.

  20. 混凝土配合比设计中骨料合理级配初探%On the Reasonable Aggregate Gradation in the Design Process of Concrete Mix Proportion

    Institute of Scientific and Technical Information of China (English)

    邵军

    2015-01-01

    This paper simply introduces the reasonable selection method of aggregate gradation and sand coarse aggregate ratio in the design process of concrete mix proportion, expounds the importance of the reasonable graduation and the selection of sand coarse aggregate ratio.%简要介绍混凝土配合比设计过程中粗骨料级配和砂率的合理选取方法,阐述了合理级配、砂率选取的重要性。

  1. Utilization of Six Sigma in Quality Improvement of Recycled Aggregates Concrete

    Directory of Open Access Journals (Sweden)

    Mohamad Terro

    2013-01-01

    Full Text Available The use of recycled demolished concrete in producing new concrete is an established method to improve sustainability through reducing the environmental impact of using virgin aggregates and through reducing construction waste. Six sigma is a set of tools and strategies for process improvement. In this paper, the six sigma DMAIC methodology is utilized to optimize the design parameters in order to improve and assure the quality of the resulting recycled aggregate concrete. The project aims to produce concrete with compressive strength of 25 MPa without using additives. Five parameters were used in the initial analysis that were reduced to three after refinement. The refined parameters are the ratio of recycled coarse aggregates, the ratio of recycled fine aggregates, and the water/cement ratio. It was concluded that the optimum values for the three parameters are 26%, 30%, and 0.5, in order.

  2. Aggregate Demand and Supply

    OpenAIRE

    Farmer, Roger E.A.

    2007-01-01

    This paper is part of a broader project that provides a microfoundation to the General Theory of J.M. Keynes. I call this project 'old Keynesian economics' to distinguish it from new-Keynesian economics, a theory that is based on the idea that to make sense of Keynes we must assume that prices are sticky. I describe a multi-good model in which I interpret the definitions of aggregate demand and supply found in the General Theory through the lens of a search theory of the labor market. I argue...

  3. REVLD: A coarse-grained model for polymers

    NARCIS (Netherlands)

    A.G. Bailey; C.P. Lowe; A.P. Sutton

    2009-01-01

    A new model for polymers is presented. REVLD (Rigid, Excluded Volume, Langevin Dynamics) is similar to the coarse-grained, bead spring model for linear chains except that the inter-bead distance is rigidly constrained instead of using an inter-bead potential to encapsulate the connectivity. Static a

  4. Organic matter dynamics in coarse sandy calcareous soils

    NARCIS (Netherlands)

    Pronk, A.A.; Reuler, van H.

    2011-01-01

    The decomposition of organic matter in coarse sandy calcareous soils (beach sand) is thought to be much higher than in acid fine sandy soils but relatively little research is performed on these soils. Laboratory incubation experiments in which the release of soil carbon (C) is determined may overest

  5. Coarse graining and scaling in dissipative particle dynamics

    DEFF Research Database (Denmark)

    Füchslin, Rudolf M; Fellermann, Harold; Eriksson, Anders;

    2009-01-01

    Dissipative particle dynamics (DPD) is now a well-established method for simulating soft matter systems. However, its applicability was recently questioned because some investigations showed an upper coarse-graining limit that would prevent the applicability of the method to the whole mesoscopic ...

  6. Improved Angle Potentials for Coarse-Grained Molecular Dynamics Simulations

    NARCIS (Netherlands)

    Bulacu, Monica; Goga, Nicolae; Zhao, Wei; Rossi, Giulia; Monticelli, Luca; Periole, Xavier; Tieleman, D. Peter; Marrink, Siewert J.

    2013-01-01

    Potentials routinely used in atomistic molecular dynamics simulations are not always suitable for modeling systems at coarse-grained resolution. For example, in the calculation of traditional torsion angle potentials, numerical instability is often encountered in the case of very flexible molecules.

  7. Martini Coarse-Grained Force Field : Extension to Carbohydrates

    NARCIS (Netherlands)

    Lopez, Cesar A.; Rzepiela, Andrzej J.; de Vries, Alex H.; Dijkhuizen, Lubbert; Huenenberger, Philippe H.; Marrink, Siewert J.; Hünenberger, Philippe H.

    2009-01-01

    We present an extension of the Martini coarse-grained force field to carbohydrates. The parametrization follows the same philosophy as was used previously for lipids and proteins, focusing on the reproduction of partitioning free energies of small compounds between polar and nonpolar phases. The car

  8. Coarse-graining stochastic biochemical networks: adiabaticity and fast simulations

    Energy Technology Data Exchange (ETDEWEB)

    Nemenman, Ilya [Los Alamos National Laboratory; Sinitsyn, Nikolai [Los Alamos National Laboratory; Hengartner, Nick [Los Alamos National Laboratory

    2008-01-01

    We propose a universal approach for analysis and fast simulations of stiff stochastic biochemical kinetics networks, which rests on elimination of fast chemical species without a loss of information about mesoscoplc, non-Poissonian fluctuations of the slow ones. Our approach, which is similar to the Born-Oppenhelmer approximation in quantum mechanics, follows from the stochastic path Integral representation of the cumulant generating function of reaction events. In applications with a small number of chemIcal reactions, It produces analytical expressions for cumulants of chemical fluxes between the slow variables. This allows for a low-dimensional, Interpretable representation and can be used for coarse-grained numerical simulation schemes with a small computational complexity and yet high accuracy. As an example, we derive the coarse-grained description for a chain of biochemical reactions, and show that the coarse-grained and the microscopic simulations are in an agreement, but the coarse-gralned simulations are three orders of magnitude faster.

  9. Free-energy coarse-grained potential for C60

    International Nuclear Information System (INIS)

    We propose a new deformable free energy method for generating a free-energy coarse-graining potential for C60. Potentials generated from this approach exhibit a strong temperature dependence and produce excellent agreement with benchmark fully atomistic molecular dynamics simulations. Parameter sets for analytical fits to this potential are provided at four different temperatures

  10. Dileptons in a coarse-grained transport approach

    CERN Document Server

    van Hees, H; Weil, J; Bleicher, M

    2015-01-01

    We calculate dilepton spectra in heavy-ion collisions using a coarse-graining approach to the simulation of the created medium with the UrQMD transport model. This enables the use of dilepton-production rates evaluated in equilibrium quantum-field theory at finite temperatures and chemical potentials.

  11. Terrain aided navigation for autonomous underwater vehicles with coarse maps

    Science.gov (United States)

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian

    2016-09-01

    Terrain aided navigation (TAN) is a form of geophysical localization technique for autonomous underwater vehicles (AUVs) operating in GPS-denied environments. TAN performance on sensor-rich AUVs has been evaluated in sea trials. However, many challenges remain before TAN can be successfully implemented on sensor-limited AUVs, especially with coarse maps. To improve TAN performance over coarse maps, a Gaussian process (GP) is proposed for the modeling of bathymetric terrain and integrated into the particle filter (GP-PF). GP is applied to provide not only the bathymetric value prediction through learning a set of bathymetric data from coarse maps but also the variance of the prediction. As a measurement update, calculated on bathymetric deviation is performed through the PF to obtain absolute and bounded positioning accuracy. Through the analysis of TAN performance on experimental data for two different terrains with map resolutions of 10–50 m, both the ability of the proposed model to represent the actual bathymetric terrain with accuracy and the effect of the GP-PF for TAN on sensor-limited systems in suited terrain are demonstrated. The experiment results further verify that there is an inverse relationship between the coarseness of the map and the overall TAN accuracy in rough terrains, but there is hardly any relationship between them in relatively flat terrains.

  12. On coarse projective integration for atomic deposition in amorphous systems

    Energy Technology Data Exchange (ETDEWEB)

    Chuang, Claire Y., E-mail: yungc@seas.upenn.edu, E-mail: meister@unm.edu, E-mail: zepedaruiz1@llnl.gov; Sinno, Talid, E-mail: talid@seas.upenn.edu [Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 South 33rd Street, 311A Towne Building, Philadelphia, Pennsylvania 19104 (United States); Han, Sang M., E-mail: yungc@seas.upenn.edu, E-mail: meister@unm.edu, E-mail: zepedaruiz1@llnl.gov [Department of Chemical and Biological Engineering, University of New Mexico, 1 University of New Mexico, MSC01 1120, Albuquerque, New Mexico 87131 (United States); Zepeda-Ruiz, Luis A., E-mail: yungc@seas.upenn.edu, E-mail: meister@unm.edu, E-mail: zepedaruiz1@llnl.gov [Lawrence Livermore National Laboratory, P.O. Box 808, L-367, Livermore, California 94550 (United States)

    2015-10-07

    Direct molecular dynamics simulation of atomic deposition under realistic conditions is notoriously challenging because of the wide range of time scales that must be captured. Numerous simulation approaches have been proposed to address the problem, often requiring a compromise between model fidelity, algorithmic complexity, and computational efficiency. Coarse projective integration, an example application of the “equation-free” framework, offers an attractive balance between these constraints. Here, periodically applied, short atomistic simulations are employed to compute time derivatives of slowly evolving coarse variables that are then used to numerically integrate differential equations over relatively large time intervals. A key obstacle to the application of this technique in realistic settings is the “lifting” operation in which a valid atomistic configuration is recreated from knowledge of the coarse variables. Using Ge deposition on amorphous SiO{sub 2} substrates as an example application, we present a scheme for lifting realistic atomistic configurations comprised of collections of Ge islands on amorphous SiO{sub 2} using only a few measures of the island size distribution. The approach is shown to provide accurate initial configurations to restart molecular dynamics simulations at arbitrary points in time, enabling the application of coarse projective integration for this morphologically complex system.

  13. Coarse-graining and scaling in dissipative particle dynamics

    DEFF Research Database (Denmark)

    Fuechslin, Rudolf; Fellermann, Harold; Eriksson, Anders;

    2009-01-01

    Dissipative particle dynamics (DPD) is now a well-established method for simulating soft matter systems. However, its applicability was recently questioned because some investigations showed an upper coarse-graining limit that would prevent the applicability of the method to the whole mesoscopic...

  14. Terrain aided navigation for autonomous underwater vehicles with coarse maps

    Science.gov (United States)

    Zhou, Ling; Cheng, Xianghong; Zhu, Yixian

    2016-09-01

    Terrain aided navigation (TAN) is a form of geophysical localization technique for autonomous underwater vehicles (AUVs) operating in GPS-denied environments. TAN performance on sensor-rich AUVs has been evaluated in sea trials. However, many challenges remain before TAN can be successfully implemented on sensor-limited AUVs, especially with coarse maps. To improve TAN performance over coarse maps, a Gaussian process (GP) is proposed for the modeling of bathymetric terrain and integrated into the particle filter (GP-PF). GP is applied to provide not only the bathymetric value prediction through learning a set of bathymetric data from coarse maps but also the variance of the prediction. As a measurement update, calculated on bathymetric deviation is performed through the PF to obtain absolute and bounded positioning accuracy. Through the analysis of TAN performance on experimental data for two different terrains with map resolutions of 10-50 m, both the ability of the proposed model to represent the actual bathymetric terrain with accuracy and the effect of the GP-PF for TAN on sensor-limited systems in suited terrain are demonstrated. The experiment results further verify that there is an inverse relationship between the coarseness of the map and the overall TAN accuracy in rough terrains, but there is hardly any relationship between them in relatively flat terrains.

  15. Non-Steady Oscillatory Flow in Coarse Granular Materials

    DEFF Research Database (Denmark)

    Andersen, O. H.; Gent, M. R. A. van; Meer, J. W. van der;

    1992-01-01

    Stationary and oscillatory flow through coarse granular materials have been investigated experimentally at Delft Hydraulics in their oscillating water tunnel with the objective of determining the coefficients of the extended Forchheimer equation. Cylinders, spheres and different types of rock have....... Further, for the non-stationary term, the virtual mass coefficient will be derived....

  16. Stationary and oscillatory flow through coarse porous media

    NARCIS (Netherlands)

    Van Gent, M.R.A.

    1993-01-01

    Measurements in a U-tube tunnel were carried out to study flow through coarse granular material. Tests with stationary flow and tests with oscillatory flow were done to study the differences between both. The coefficients from the extended Forchheimer equation, which is supposed to describe non-stat

  17. Notes on coarse grainings and functions of observables

    CERN Document Server

    Dvurecenskij, A; Pulmannova, S; Ylinen, K

    2004-01-01

    Using the Naimark dilation theory we investigate the question under what conditions an observable which is a coarse graining of another observable is a function of it. To this end, conditions for the separability and for the Boolean structure of an observable are given.

  18. Emanation-thermal analysis of basalt fiber adsorbents

    International Nuclear Information System (INIS)

    Complex emanation-thermal analysis is used for investigating structural changes in basalt adsorbents taking place during thermal affects on material. Adsorbent is prepared by two-stage treatment of staple basalt fibers by hydrochloric acid. Isotherms of sorption of liquid nitrogen vapors by new sorbents are measured. Areas of the open surface, porosity and pores size spectra of leached fibers are calculated. It is determined by the method of thermostimulated gassing that adsorbed water is in two energetically different states in porous basalt fiber: basic part of water vapors is desorbed at 90-110 Deg C, remained part -at 300-320 Deg C. Full regeneration of sorbent requires warming up to 550 Deg C

  19. Evidence against hydrogen-based microbial ecosystems in basalt aquifers

    Science.gov (United States)

    Anderson; Chapelle; Lovley

    1998-08-14

    It has been proposed that hydrogen produced from basalt-ground-water interactions may serve as an energy source that supports the existence of microorganisms in the deep subsurface on Earth and possibly on other planets. However, experiments demonstrated that hydrogen is not produced from basalt at an environmentally relevant, alkaline pH. Small amounts of hydrogen were produced at a lower pH in laboratory incubations, but even this hydrogen production was transitory. Furthermore, geochemical considerations suggest that previously reported rates of hydrogen production cannot be sustained over geologically significant time frames. These findings indicate that hydrogen production from basalt-ground-water interactions may not support microbial metabolism in the subsurface.

  20. Investigation of basalt plastic reinforcement and its Adhesion with Concrete

    Directory of Open Access Journals (Sweden)

    Kustikova Yulia Olegovna

    2014-03-01

    Full Text Available The load-bearing capacity and durability of concrete structures with metal or other reinforcement depends on their physical and mechanical properties and adhesion values with concrete. In this regard, there is an urgent need in the definition of adhesion of basalt reinforcement and concrete of various compositions and classes. One of the main problems with the use of basalt rods in concrete structures is - providing a high degree of load-carrying capacity in different conditions of stress-strain state of the structure, and the related amount of its adhesion with concrete. Meeting these requirements can be achieved with load-bearing capacity of individual rods, adhesion value, in general, of basalt reinforcement with concrete.

  1. Petrogenesis of pillow basalts from Baolai in southwestern Taiwan

    Science.gov (United States)

    Liu, Chih-Chun; Yang, Huai-Jen

    2016-04-01

    The pillow basalts from Baolai in southwestern Taiwan have been inferred to bear Dupal signautres based on their Th/Ce ratio, linking the Baolai basalts to the South China Sea (SCS) seamounts that are characterized by Dupal Pb isotope signatures (Smith and Lewis, 2007). In this study, thirty-two Baolai basalt samples were analyzed for abundances of major and trace elements as well as Pb and Nd isotope ratios to verify their Dupal characters and to constrain their petrogenesis significance. The Baolai basalts contain 4-10 % L.O.I.. Three stages of alteration are inferred from plots of L.O.I. abundance versus concentrations major oxides as well as mineral textures and compositions. The first alteration stage was characterized by albitization that converted Ca-rich plagioclase to albite. The second alteration stage was dominated by chloritization of olivine and augite, resulting in increases in L.O.I. abundance. The last alteration stage is represented by formation of secondary calcite in vesicles and cracks. These alteration processes reflect interaction with seawater and apparently did not affect the magmatic Pb isotope composition for the low Pb concentration in seawater. Relative to the North Hemisphere Reference Line (NHRL), the Baolai pillow basalts have higher 208Pb/204Pb ratios at a given 206Pb/204Pb value, showing Dupal anomaly. For their relatively higher 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb ratios, the Baolai basalts are distinct from majority of the Cenozoic basalts in the Hainan-Leizhou peninsula, the Indochina peninsula, and the SCS seamounts, for which derivation from the Hainan mantle plume has been recently proposed (Wang et al., 2013). In contrast, the Baolai basalts and the Cenozoic basalts from eastern Guangdong at southeastern China have similar Pb and Nd isotope compositions, indicating derivation from similar mantle sources. However, the Baolai basalts have lower abundance ratios of Zr/Hf (40.3-45.6 versus 46.5-50.5), La/Yb (12

  2. Effect of Aggregate Gradation with Fuller Distribution on Properties of Sulphoaluminate Cement Concrete

    Institute of Scientific and Technical Information of China (English)

    GONG Chenchen; ZHANG Jie; WANG Shoude; LU Lingchao

    2015-01-01

    Experimental investigations on mechanical property and durability of sulphoaluminate cement concrete with aggregate gradations according to Fuller distribution are presented in this paper. Compressive strength, water impermeability and resistance capability to sulfate attack of SACC have the same trend of concrete with fine aggregates of Fuller distribution gradationcoarse aggregates of Fuller distribution gradationaggregates of Fuller distribution gradation. The relationship between bulk density of aggregate and water penetration depth obeyed the second-order polynomialy=0.002x2-6.863 8x+5 862.3, and had a notable correlationR2=0.979 9. The sulphoaluminate cement concrete with total aggregate gradation with Fuller distribution forh=0.50 had the best resistance capability to sulfate attack. It was a second-order polynomial relationship between bulk density of aggregates and water penetration depth of y=0.002x2-6.863 8x+5 862.3 withR2=0.979 9, which indicated notable correlation. The iftting formula between bulk density of aggregates and sulfate resistance coefifcient of SACC wasy=0.000 5x+0.370 4 withR2=0.958 5.

  3. The Influence of Crushed Concrete Demolition Waste Aggregates on the Hardening Process of Concrete Mixtures

    Directory of Open Access Journals (Sweden)

    Olga FINOŽENOK

    2013-03-01

    Full Text Available Concrete – complex structure composite material consisting of the components with various structure and size. Not only coarse and fine aggregates are used in concrete production, but also filler aggregates. Aggregates of natural, man-made origin or aggregates, produced from recycled materials, can be utilised in concrete production. Aggregates can be produced from recycled materials by reprocessing of concrete and reinforced concrete waste. The influence of the filler aggregates produced from the crushed concrete waste on the characteristics of binder’s paste, when part of the binder (5; 10; 15; 20; 25; 30 % is replaced by such filler aggregate, is analysed in the research. Concrete mixtures with natural aggregates and crushed concrete waste were selected and concrete mixtures of required consistence were produced during the research. Exothermic reactions take place during the hardening of concrete mixture, at that time the heat is dissipated, which increases the temperature of the concrete sample. Thus the exothermic processes were investigated during the concrete’s mixture hardening period and the temperatures of exothermic reactions were determined.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3833

  4. Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst

    Directory of Open Access Journals (Sweden)

    Hebé Gurdián

    2014-04-01

    Full Text Available The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes.

  5. Basalt fiber reinforced polymer composites: Processing and properties

    Science.gov (United States)

    Liu, Qiang

    A high efficiency rig was designed and built for in-plane permeability measurement of fabric materials. A new data derivation procedure to acquire the flow fluid pattern in the experiment was developed. The measurement results of the in-plane permeability for basalt twill 31 fabric material showed that a high correlation exists between the two principal permeability values for this fabric at 35% fiber volume fraction. This may be the most important scientific contribution made in this thesis. The results from radial measurements corresponded quite well with those from Unidirectional (UD) measurements, which is a well-established technique. No significant differences in mechanical properties were found between basalt fabric reinforced polymer composites and glass composites reinforced by a fabric of similar weave pattern. Aging results indicate that the interfacial region in basalt composites may be more vulnerable to environmental damage than that in glass composites. However, the basalt/epoxy interface may have been more durable than the glass/epoxy interface in tension-tension fatigue because the basalt composites have significantly longer fatigue life. In this thesis, chapter I reviews the literature on fiber reinforced polymer composites, with concentration on permeability measurement, mechanical properties and durability. Chapter II discusses the design of the new rig for in-plane permeability measurement, the new derivation procedure for monitoring of the fluid flow pattern, and the permeability measurement results. Chapter III compares the mechanical properties and durability between basalt fiber and glass fiber reinforced polymer composites. Lastly, chapter IV gives some suggestions and recommendations for future work.

  6. Sulfate attack and reinforcement corrosion in concrete with recycled concrete aggregates and supplementary cementing materials

    OpenAIRE

    Corral Higuera, Ramón; Arredondo Rea, Susana Paola; Neri Flores, M.A.; Gómez Soberón, José Manuel Vicente; Almeraya Calderón, F.; Castorena González, J.H.; Almaral Sánchez, Jorge Luis

    2011-01-01

    As strategies to contribute to the concrete industry sustainability, reinforced concrete was fabricated using recycled concrete coarse aggregate and replacing partially portland cement with supplementary cementing materials as fly ash and silica fume. On test specimens, partially immersed in 3.5% Na2SO4 aqueous solution, the effect of the recycled and supplementary materials against sulfate attack and reinforcement corrosion was evaluated. For such aim, weight loss of concrete and corrosion p...

  7. Characterization of Concrete made with Recycled Aggregate from Ceramic Sanitary Ware

    Directory of Open Access Journals (Sweden)

    Medina, C.

    2011-12-01

    Full Text Available This study examined the possibility of reusing the ceramic wastes of sanitary ware as coarse aggregate, in partial substitution (15, 20 y 25 % of natural coarse aggregates. Firstly, the characterization of recycled coarse ceramic aggregate was carried out subsequently proceeded to establish the parameters of dosage and manufacture of different concretes. Lastly, tests were conducted using these mixes to characterize physical and mechanical, and a study was carried out to identify the crystalline phases. Results showed that as the substitution proportion increased, the mechanical properties of the concrete improved, whilst physical properties remained practically constant. In view of these results, we conclude that it is possible to use this type of ceramic waste as coarse aggregate when mixing concrete destined for structural purposes.

    En este estudio se plantea la posibilidad de reutilizar los residuos cerámicos de sanitarios como árido grueso sustituyendo de forma parcial (15, 20 y 25 % al árido grueso natural. Para ello, se llevó a cabo la caracterización del árido cerámico reciclado y posteriormente se procedió a establecer los parámetros de dosificación y fabricación de los distintos hormigones. Finalmente, se realizó sobre los mismos unos ensayos de caracterización de las propiedades físicas y mecánicas, y un estudio de las fases cristalinas. Los resultados indican que a medida que se aumenta el porcentaje de sustitución se ven mejoradas las propiedades mecánicas de estos, mientras que las propiedades físicas se mantienen prácticamente constantes. A la vista de estos resultados se puede concluir que es posible la utilización de este tipo de residuo cerámico como árido grueso en la elaboración de hormigones con fines estructurales.

  8. Effect of the aggregate grading on the concrete air permeability

    Directory of Open Access Journals (Sweden)

    Argiz, C.

    2014-09-01

    Full Text Available Great durability problems are being found in concrete structures related to the penetrability of aggressive agents through the concrete (ie. chloride penetration, sulphate attack, carbonation, freezing and thawing, and so on. Air permeability coefficient is used as an effective tool to estimate the potential durability of concrete structures due to its direct relation with the microstructure and the moisture content. This paper discusses the effect of the aggregate grading and water/cement ratio on the air permeability coefficient. An aggregate grading with more sand than coarse aggregates has resulted more beneficial from the point of view of concrete air permeability. This fact can be attributed to a denser skeleton formed by the finer aggregates. With fine aggregates, the higher water/cement ratio, the lower air permeability. However, the contrary was found with coarse aggregates. Overall, a temperature increase from 20 °C to 60 °C during preconditioning led to a Dair increase of 40–80%.Se han encontrado una gran cantidad de problemas de durabilidad de estructuras de hormigón relacionados con la penetración de agentes agresivos externos (es decir, penetración de cloruros, ataque por sulfatos, carbonatación, hielo-deshielo, etc.. El coeficiente de permeabilidad al aire se utiliza como una herramienta eficaz para estimar la durabilidad potencial de las estructuras de hormigón debido a su relación directa con su microestructura y contenido de humedad. Se discute el efecto de la gradación de los áridos y relación agua/cemento en el coeficiente de permeabilidad al aire. Con áridos más finos que gruesos, el resultado es más beneficioso, lo que se atribuye a que la arena forma un esqueleto más denso. Con áridos más finos, al aumentar la relación agua/cemento, disminuye la permeabilidad al aire; pero con áridos más gruesos se ha observado lo contrario. Cuando se pre-acondiciona de 20 °C a 60 °C, se produce un aumento del Dair

  9. Seismic wave propagation through an extrusive basalt sequence

    Science.gov (United States)

    Sanford, Oliver; Hobbs, Richard; Brown, Richard; Schofield, Nick

    2016-04-01

    Layers of basalt flows within sedimentary successions (e.g. in the Faeroe-Shetland Basin) cause complex scattering and attenuation of seismic waves during seismic exploration surveys. Extrusive basaltic sequences are highly heterogeneous and contain strong impedance contrasts between higher velocity crystalline flow cores (˜6 km s-1) and the lower velocity fragmented and weathered flow crusts (3-4 km s-1). Typically, the refracted wave from the basaltic layer is used to build a velocity model by tomography. This velocity model is then used to aid processing of the reflection data where direct determination of velocity is ambiguous, or as a starting point for full waveform inversion, for example. The model may also be used as part of assessing drilling risk of potential wells, as it is believed to constrain the total thickness of the sequence. In heterogeneous media, where the scatter size is of the order of the seismic wavelength or larger, scattering preferentially traps the seismic energy in the low velocity regions. This causes a build-up of energy that is guided along the low velocity layers. This has implications for the interpretation of the observed first arrival of the seismic wave, which may be a biased towards the low velocity regions. This will then lead to an underestimate of the velocity structure and hence the thickness of the basalt, with implications for the drilling of wells hoping to penetrate through the base of the basalts in search of hydrocarbons. Using 2-D acoustic finite difference modelling of the guided wave through a simple layered basalt sequence, we consider the relative importance of different parameters of the basalt on the seismic energy propagating through the layers. These include the proportion of high to low velocity material, the number of layers, their thickness and the roughness of the interfaces between the layers. We observe a non-linear relationship between the ratio of high to low velocity layers and the apparent velocity

  10. Age of the youngest Palaeogene flood basalts in East Greenland

    DEFF Research Database (Denmark)

    Heilmann-Clausen, C.; Piasecki, Stefan; Abrahamsen, Niels;

    2008-01-01

    Intra-basaltic sediments 50 m below the top of the Paleogene lava succession at Kap Dalton, East Greenland, contain dinoflagellate cysts of late Ypresian-earliest Lutetian age, while sediments immediately above the lavas contain an assemblage of early Lutetian age. Combined with paleomagnetic...... results, this constrains the termination of the East Greenland Paleogene Igneous Province to the Early-Middle Eocene transition (nannoplankton chronozones NP13-NP14/earliest NP15). This is 6-8 Ma younger than according to previous biostratigraphic age assignments. The new data show that flood basalt...

  11. Friction Joint Between Basalt-Reinforced Composite and Aluminum

    DEFF Research Database (Denmark)

    Costache, Andrei; Glejbøl, Kristian; Sivebæk, Ion Marius;

    2015-01-01

    The purpose of this study was to anchor basalt-reinforced polymers in an aluminum grip using dry friction. Dry friction clamping is considered the optimal solution for post-mounting of load-bearing terminations on composite structures. A new test method is presented for characterizing the frictio......The purpose of this study was to anchor basalt-reinforced polymers in an aluminum grip using dry friction. Dry friction clamping is considered the optimal solution for post-mounting of load-bearing terminations on composite structures. A new test method is presented for characterizing...

  12. Basaltic rocks analyzed by the Spirit Rover in Gusev Crater

    Science.gov (United States)

    McSween, H. Y.; Arvidson, R. E.; Bell, J. F., III; Blaney, D.; Cabrol, N. A.; Christensen, P. R.; Clark, B. C.; Crisp, J. A.; Crumpler, L. S.; DesMarais, D. J.; Farmer, J. D.; Gellert, R.; Ghosh, A.; Gorevan, S.; Graff, T.; Grant, J.; Haskin, L. A.; Herkenhoff, K. E.; Johnson, J. R.; Jolliff, B. L.; Klingelhoefer, G.; Morris, R. V.; Yen, A.

    2004-01-01

    The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and Mini-Thermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain Particle X-ray Spectrometer are consistent with picritic basalts, containing normative olivine, pyroxenes, plagioclase, and accessory FeTi oxides. Mossbauer, Pancam, and Mini-TES spectra confirm the presence of olivine, magnetite, and probably pyroxene. These basalts extend the known range of rock compositions composing the martian crust.

  13. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method.

    Science.gov (United States)

    Kim, Haseog; Park, Sangki; Kim, Hayong

    2016-01-01

    There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5. PMID:27483298

  14. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method

    Science.gov (United States)

    Kim, Haseog; Park, Sangki; Kim, Hayong

    2016-01-01

    There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5. PMID:27483298

  15. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method

    Directory of Open Access Journals (Sweden)

    Haseog Kim

    2016-07-01

    Full Text Available There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5.

  16. Magmatic evolution of the fresh basalts from the Ridge axis near Egaria Fracture Zone, Central Indian Ridge

    Digital Repository Service at National Institute of Oceanography (India)

    Mudholkar, A.V.

    the basalts under study. These gradual changes in the olivines and plagioclase point to a simple evolution of the basaltic magma by differentiating mineral phases from the parental basalt The resorption features observed in high forsteritic olivines (~ 89...

  17. Adaptive coarse-grained Monte Carlo simulation of reaction and diffusion dynamics in heterogeneous plasma membranes

    Directory of Open Access Journals (Sweden)

    Stamatakis Michail

    2010-04-01

    Full Text Available Abstract Background An adaptive coarse-grained (kinetic Monte Carlo (ACGMC simulation framework is applied to reaction and diffusion dynamics in inhomogeneous domains. The presented model is relevant to the diffusion and dimerization dynamics of epidermal growth factor receptor (EGFR in the presence of plasma membrane heterogeneity and specifically receptor clustering. We perform simulations representing EGFR cluster dissipation in heterogeneous plasma membranes consisting of higher density clusters of receptors surrounded by low population areas using the ACGMC method. We further investigate the effect of key parameters on the cluster lifetime. Results Coarse-graining of dimerization, rather than of diffusion, may lead to computational error. It is shown that the ACGMC method is an effective technique to minimize error in diffusion-reaction processes and is superior to the microscopic kinetic Monte Carlo simulation in terms of computational cost while retaining accuracy. The low computational cost enables sensitivity analysis calculations. Sensitivity analysis indicates that it may be possible to retain clusters of receptors over the time scale of minutes under suitable conditions and the cluster lifetime may depend on both receptor density and cluster size. Conclusions The ACGMC method is an ideal platform to resolve large length and time scales in heterogeneous biological systems well beyond the plasma membrane and the EGFR system studied here. Our results demonstrate that cluster size must be considered in conjunction with receptor density, as they synergistically affect EGFR cluster lifetime. Further, the cluster lifetime being of the order of several seconds suggests that any mechanisms responsible for EGFR aggregation must operate on shorter timescales (at most a fraction of a second, to overcome dissipation and produce stable clusters observed experimentally.

  18. Web-based computational chemistry education with CHARMMing II: Coarse-grained protein folding.

    Directory of Open Access Journals (Sweden)

    Frank C Pickard

    2014-07-01

    Full Text Available A lesson utilizing a coarse-grained (CG Gō-like model has been implemented into the CHARMM INterface and Graphics (CHARMMing web portal (www.charmming.org to the Chemistry at HARvard Macromolecular Mechanics (CHARMM molecular simulation package. While widely used to model various biophysical processes, such as protein folding and aggregation, CG models can also serve as an educational tool because they can provide qualitative descriptions of complex biophysical phenomena for a relatively cheap computational cost. As a proof of concept, this lesson demonstrates the construction of a CG model of a small globular protein, its simulation via Langevin dynamics, and the analysis of the resulting data. This lesson makes connections between modern molecular simulation techniques and topics commonly presented in an advanced undergraduate lecture on physical chemistry. It culminates in a straightforward analysis of a short dynamics trajectory of a small fast folding globular protein; we briefly describe the thermodynamic properties that can be calculated from this analysis. The assumptions inherent in the model and the data analysis are laid out in a clear, concise manner, and the techniques used are consistent with those employed by specialists in the field of CG modeling. One of the major tasks in building the Gō-like model is determining the relative strength of the nonbonded interactions between coarse-grained sites. New functionality has been added to CHARMMing to facilitate this process. The implementation of these features into CHARMMing helps automate many of the tedious aspects of constructing a CG Gō model. The CG model builder and its accompanying lesson should be a valuable tool to chemistry students, teachers, and modelers in the field.

  19. Glass and mineral chemistry of northern central Indian ridge basalts: Compositional diversity and petrogenetic significance

    Digital Repository Service at National Institute of Oceanography (India)

    Ray, Dwijesh; Banerjee, R.; Iyer, S.D.; Basavalingu, B.; Mukhopadhyay, S.

    The glass and mineral chemistry of basalts examined from the northern central Indian ridge (NCIR) provides an insight into magma genesis around the vicinity of two transform faults: Vityaz (VT) and Vema (VM). The studied mid-ocean ridge basalts...

  20. Preliminary feasibility study on storage of radioactive wastes in Columbia River basalts. Volume II

    Energy Technology Data Exchange (ETDEWEB)

    ,

    1976-11-01

    Volume II comprises four appendices: analytical data and sample locations for basalt flow type localities; Analytical data and sample locations for measured field sections in Yakima basalts; core hole lithology and analytical data; and geophysical logs. (LK)

  1. Clay mineral facies and lateritization in basalts of the southeastern Parana Basin, Brazil

    International Nuclear Information System (INIS)

    Seventeen samples from two lateritic profiles, each with five facies, were studied. These profiles occur on the old planation surface of the plateau basalts of the southern part of ParanáBasin, Brazil. Optical microscopy, X-ray diffraction, electron microprobe, Mössbauer spectroscopy and Fourier Transform Infrared Spectra were used to obtain information about the nature and chemical composition of each weathering facies. In addition, scanning electron microscopy and analyses of clay minerals were performed to detect microcrystalline environmental changes. Both profiles have two major parts: a loose red-clay latosol separated from an underlying mottled clay and an alterite facies; a stone line may or may not be present between the latosol and the underlying units. In both profiles the latosol consists principally of kaolinite, hematite and goethite. Two alterite facies, shaped by differential weathering, are also present in the lower profile: a halloysite–nontronite clayey matrix with a well developed fissure system occurs in the argillaceous alterite and a network of Al–goethite aggregates is typical of the highly porous cortex of the boulder alterite that is found in the stone line and below it. Gibbsite has crystallized in the large pores of porphyritic boulder alterite but is absent in the small pores of the subaphyric boulder alterite. Clay minerals observed in fissures include halloysite associated with goethite and manganese oxides. The basalt has hydrothermal green-clays (mixed layers and trioctahedral smectites) that formed between primary plagioclase, pyroxene and Ti–magnetite crystals while fresh corestones of the boulder alterite have cryptocrystalline iron-rich material. The study of these profiles shows one principal evolutionary trend for clay minerals. This trend is from smectite and mixed layers that form green clays in altered bedrock at the base of the profile to an intermediate association of nontronite and halloysite in the argillaceous

  2. Modifiers of mutant huntingtin aggregation

    OpenAIRE

    Teuling, Eva; Bourgonje, Annika; Veenje, Sven; Thijssen, Karen; Boer, Jelle de; van der Velde, Joeri; Swertz, Morris; Nollen, Ellen

    2011-01-01

    Protein aggregation is a common hallmark of a number of age-related neurodegenerative diseases, including Alzheimer’s, Parkinson’s, and polyglutamine-expansion disorders such as Huntington’s disease, but how aggregation-prone proteins lead to pathology is not known. Using a genome-wide RNAi screen in a C. elegans-model for polyglutamine aggregation, we previously identified 186 genes that suppress aggregation. Using an RNAi screen for human orthologs of these genes, we here present 26 human g...

  3. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.

    2014-01-01

    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

  4. Aggregation dynamics of rigid polyelectrolytes

    Science.gov (United States)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani

    2016-01-01

    Similarly charged polyelectrolytes are known to attract each other and aggregate into bundles when the charge density of the polymers exceeds a critical value that depends on the valency of the counterions. The dynamics of aggregation of such rigid polyelectrolytes are studied using large scale molecular dynamics simulations. We find that the morphology of the aggregates depends on the value of the charge density of the polymers. For values close to the critical value, the shape of the aggregates is cylindrical with height equal to the length of a single polyelectrolyte chain. However, for larger values of charge, the linear extent of the aggregates increases as more and more polymers aggregate. In both the cases, we show that the number of aggregates decrease with time as power laws with exponents that are not numerically distinguishable from each other and are independent of charge density of the polymers, valency of the counterions, density, and length of the polyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski coagulation equation with kernels determined from the molecular dynamics simulations and justify the numerically obtained value of the exponent. Our results suggest that once counterions condense, effective interactions between polyelectrolyte chains short-ranged and the aggregation of polyelectrolytes are diffusion-limited.

  5. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WUFeng-Min; WULi-Li; LUHang-Jun; LIQiao-Wen; YEGao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω; thefractal dimension decreases with increasing ω;, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  6. Fractal Aggregation Under Rotation

    Institute of Scientific and Technical Information of China (English)

    WU Feng-Min; WU Li-Li; LU Hang-Jun; LI Qiao-Wen; YE Gao-Xiang

    2004-01-01

    By means of the Monte Carlo simulation, a fractal growth model is introduced to describe diffusion-limited aggregation (DLA) under rotation. Patterns which are different from the classical DLA model are observed and the fractal dimension of such clusters is calculated. It is found that the pattern of the clusters and their fractal dimension depend strongly on the rotation velocity of the diffusing particle. Our results indicate the transition from fractal to non-fractal behavior of growing cluster with increasing rotation velocity, i.e. for small enough angular velocity ω the fractal dimension decreases with increasing ω, but then, with increasing rotation velocity, the fractal dimension increases and the cluster becomes compact and tends to non-fractal.

  7. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders;

    2014-01-01

    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  8. Notice of Release of NBR-1 Germplasm Basalt Milkvetch

    Science.gov (United States)

    Basalt milkvetch or threadstalk milkvetch (Astragalus filipes Torr. ex A. Gray) is a perennial legume that is widely distributed on rangelands in western North America and holds promise for rangeland revegetation and restoration programs. No germplasms or cultivars are commercially available for ba...

  9. Fire performance of basalt FRP mesh reinforced HPC thin plates

    DEFF Research Database (Denmark)

    Hulin, Thomas; Hodicky, Kamil; Schmidt, Jacob Wittrup;

    2013-01-01

    An experimental program was carried out to investigate the influence of basalt FRP (BFRP) reinforcing mesh on the fire behaviour of thin high performance concrete (HPC) plates applied to sandwich elements. Samples with BFRP mesh were compared to samples with no mesh, samples with steel mesh...

  10. Interpreting chemical compositions of small scale basaltic systems: A review

    Science.gov (United States)

    McGee, Lucy E.; Smith, Ian E. M.

    2016-10-01

    Small scale basaltic magmatic systems occur in all of the major tectonic environments of planet Earth and are characteristically expressed at the Earth's surface as fields of small monogenetic cones. The chemical compositions of the materials that make up these cones reflect processes of magma generation and differentiation that occur in their plumbing system. The volumes of magmas involved are very small and significantly their compositional ranges reveal remarkably complex processes which are overwhelmed or homogenized in larger scale systems. Commonly, compositions are basaltic, alkalic and enriched in light rare earth elements and large ion lithophile elements, although the spectrum extends from highly enriched nephelinites to subalkalic and tholeiitic basalts. Isotopic analyses of rocks from volcanic fields almost always display compositions which can only be explained by the interaction of two or more mantle sources. Ultimately their basaltic magmas originate by small scale melting of mantle sources. Compositional variety is testament to melting processes at different depths, a range of melting proportions, a heterogeneous source and fractionation, magma mixing and assimilation within the plumbing system that brings magmas to the surface. The fact that such a variety of compositions is preserved in a single field shows that isolation of individual melting events and their ascent is an important and possibly defining feature of monogenetic volcanism, as well as the window their chemical behavior provides into the complex process of melt generation and extraction in the Earth's upper mantle.

  11. [The dust factor in the manufacture of basalt fibers].

    Science.gov (United States)

    Gorban', L N; Riazanov, A V; Voloboeva, A A; Rybak, E A

    1996-01-01

    A study was made of the labour conditions of those workers engaged in the production of basalt fibre (BF). Morphological makeup is examined as is dispersity and cytotoxicity of the dust produced in the process of BF making. An issue is addressed of usefulness of setting special hygienic regulations for BF dust.

  12. Nuclear waste package materials testing report: basaltic and tuffaceous environments

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D.J.; Coles, D.G.; Hodges, F.N.; McVay, G.L.; Westerman, R.E.

    1983-03-01

    The disposal of high-level nuclear wastes in underground repositories in the continental United States requires the development of a waste package that will contain radionuclides for a time period commensurate with performance criteria, which may be up to 1000 years. This report addresses materials testing in support of a waste package for a basalt (Hanford, Washington) or a tuff (Nevada Test Site) repository. The materials investigated in this testing effort were: sodium and calcium bentonites and mixtures with sand or basalt as a backfill; iron and titanium-based alloys as structural barriers; and borosilicate waste glass PNL 76-68 as a waste form. The testing also incorporated site-specific rock media and ground waters: Reference Umtanum Entablature-1 basalt and reference basalt ground water, Bullfrog tuff and NTS J-13 well water. The results of the testing are discussed in four major categories: Backfill Materials: emphasizing water migration, radionuclide migration, physical property and long-term stability studies. Structural Barriers: emphasizing uniform corrosion, irradiation-corrosion, and environmental-mechanical testing. Waste Form Release Characteristics: emphasizing ground water, sample surface area/solution volume ratio, and gamma radiolysis effects. Component Compatibility: emphasizing solution/rock, glass/rock, glass/structural barrier, and glass/backfill interaction tests. This area also includes sensitivity testing to determine primary parameters to be studied, and the results of systems tests where more than two waste package components were combined during a single test.

  13. Nuclear waste package materials testing report: basaltic and tuffaceous environments

    International Nuclear Information System (INIS)

    The disposal of high-level nuclear wastes in underground repositories in the continental United States requires the development of a waste package that will contain radionuclides for a time period commensurate with performance criteria, which may be up to 1000 years. This report addresses materials testing in support of a waste package for a basalt (Hanford, Washington) or a tuff (Nevada Test Site) repository. The materials investigated in this testing effort were: sodium and calcium bentonites and mixtures with sand or basalt as a backfill; iron and titanium-based alloys as structural barriers; and borosilicate waste glass PNL 76-68 as a waste form. The testing also incorporated site-specific rock media and ground waters: Reference Umtanum Entablature-1 basalt and reference basalt ground water, Bullfrog tuff and NTS J-13 well water. The results of the testing are discussed in four major categories: Backfill Materials: emphasizing water migration, radionuclide migration, physical property and long-term stability studies. Structural Barriers: emphasizing uniform corrosion, irradiation-corrosion, and environmental-mechanical testing. Waste Form Release Characteristics: emphasizing ground water, sample surface area/solution volume ratio, and gamma radiolysis effects. Component Compatibility: emphasizing solution/rock, glass/rock, glass/structural barrier, and glass/backfill interaction tests. This area also includes sensitivity testing to determine primary parameters to be studied, and the results of systems tests where more than two waste package components were combined during a single test

  14. Basalt Waste Isolation Project. Annual report, fiscal year 1979

    International Nuclear Information System (INIS)

    This project is aimed at examining the feasibility and providing the technology to design and construct a radwaste repository in basalt formations beneath and within the Hanford Site. The project is divided into seven areas: systems integration, geosciences, hydrologic studies, engineered barriers, near-surface test facility, engineering testing, and repository engineering. This annual report summarizes key investigations in these seven areas

  15. Loading-unloading test analysis of anisotropic columnar jointed basalts

    Institute of Scientific and Technical Information of China (English)

    Zhi-gang SHAN; Sheng-jie DI

    2013-01-01

    To evaluate the columnar jointed basalts in the dam site of Baihetan hydropower station in southwest China,we developed a basic conceptual model of single jointed rock mass.Considering that the rock mass deformation consists of rock block deformation and joints deformation,the linear mechanical characteristics of the cell(including the elastic joints and the nonlinear mechanical behaviors of the cell)with a combined frictional-elastic interface were analyzed.We developed formulas to calculate the rock block deformation,which can be adapted for multiple jointed rock mass and columnar jointed basalts.The formulas are effective in calculating the equivalent modulus of multiple jointed rock mass,and precisely reveal the anisotropic properties of columnar jointed basalts.Furthermore,the in situ rigid bearing plate tests were analyzed and calculated,and the types of loading-unloading curves and the equivalent modulus along different directions of columnar jointed basalts were obtained.The analytical results are in close compliance with the test results.

  16. Basalt nuclear-waste repository remote sensing using electromagnetic techniques

    International Nuclear Information System (INIS)

    The electromagnetic permittivity and attenuation rate of basalt, from the Near Surface Test Facility of the Basalt Waste Isolation Project at Hanford, Washington, have been measured in the laboratory as a function of water content at frequencies from 25 MHz to 1000 MHz. Both the permittivity and the attenuation rate are strongly related to water content of basalt in this frequency range. Completely dehydrated, the rock has a frequency-independent relative permittivity of about 8 and attenuation rates (inverse skin depths) of 0.04 m-1 and 3.2 m-1 at 25 MHz and 1000 MHz, respectively. When completely saturated by tap water to 6% by volume, the relative permittivity ranges from 16.5 to 10.0 and the attenuation ranges from 0.3 m-1 to 5.5 m-1 between 25 MHz and 1000 MHz. The data indicate that high-frequency electromagnetic remote sensing techniques, such as those used in radar, cross-borehole tomography, and borehole logging, may be useful in characterizing proposed basalt repositories and monitoring established waste repositories. Electromagnetic methods are particularly suited to delineating water content of the rock and, when completely saturated, crack and pore porosity of the rock mass within a repository. 7 references, 3 figures

  17. Coarse Grainings and Irreversibility in Quantum Field Theory

    CERN Document Server

    Anastopoulos, C

    1997-01-01

    In this paper we are interested in the studying coarse-graining in field theories using the language of quantum open systems. Motivated by the ideas of Calzetta and Hu on correlation histories we employ the Zwanzig projection technique to obtain evolution equations for relevant observables in self-interacting scalar field theories. Our coarse-graining operation consists in concentrating solely on the evolution of the correlation functions of degree less than $n$, a treatment which corresponds to the familiar from statistical mechanics truncation of the BBKGY hierarchy at the n-th level. We derive the equations governing the evolution of mean field and two-point functions thus identifying the terms corresponding to dissipation and noise. We discuss possible applications of our formalism, the emergence of classical behaviour and the connection to the decoherent histories framework.

  18. Adaptive Genetic Algorithm for Sensor Coarse Signal Processing

    Directory of Open Access Journals (Sweden)

    Xuan Huang

    2014-03-01

    Full Text Available As with the development of computer technology and informatization, network technique, sensor technique and communication technology become three necessary components of information industry. As the core technique of sensor application, signal processing mainly determines the sensor performances. For this reason, study on signal processing mode is very important to sensors and the application of sensor network. In this paper, we introduce a new sensor coarse signal processing mode based on adaptive genetic algorithm. This algorithm selects crossover, mutation probability adaptively and compensates multiple operators commutatively to optimize the search process, so that we can obtain the global optimum solution. Based on the proposed algorithm, using auto-correlative characteristic parameter extraction method, it achieves smaller test error in sensor coarse signal processing mode of processing interference signal. We evaluate the proposed approach on a set of data. The experimental results show that, the proposed approach is able to improve the performance in different experimental setting

  19. A detection of the coarse water droplets in steam turbines

    Directory of Open Access Journals (Sweden)

    Bartoš Ondřej

    2014-03-01

    Full Text Available The aim of this paper is to introduce a novel method for the detection of coarse water droplets in a low pressure part of steam turbines. The photogrammetry method has been applied for the measurement of coarse droplets in the low-pressure part of a steam turbine. A new probe based on this measurement technique was developed and tested in the laboratory and in a steam turbine in the Počerady power-plant. The probe was equipped with state-of-the-art instrumentation. The paper contains results from laboratory tests and the first preliminary measurements in a steam turbine. Possible applications of this method have been examined.

  20. Maximal and reduced Roe algebras of coarsely embeddable spaces

    CERN Document Server

    Spakula, Jan

    2011-01-01

    Gong, Wang and Yu introduced a maximal, or universal, version of the Roe C*-algebra associated to a metric space. We study the relationship between this maximal Roe algebra and the usual version, in both the uniform and non-uniform cases. The main result is that if a (uniformly discrete, bounded geometry) metric space X coarsely embeds in a Hilbert space, then the canonical map between the maximal and usual (uniform) Roe algebras induces an isomorphism on K-theory. We also give a simple proof that if X has property A, then the maximal and usual (uniform) Roe algebras are the same. These two results are natural coarse-geometric analogues of certain well-known implications of a-T-menability and amenability for group C*-algebras. The techniques used are E-theoretic, building on work of Higson-Kasparov-Trout and Yu.

  1. A nucleotide-level coarse-grained model of RNA

    CERN Document Server

    Šulc, Petr; Ouldridge, Thomas E; Doye, Jonathan P K; Louis, Ard A

    2014-01-01

    We present a new, nucleotide-level model for RNA, oxRNA, based on the coarse-graining methodology recently developed for the oxDNA model of DNA. The model is designed to reproduce structural, mechanical and thermodynamic properties of RNA, and the coarse-graining level aims to retain the relevant physics for RNA hybridization and the structure of single- and double-stranded RNA. In order to explore its strengths and weaknesses, we test the model in a range of nanotechnological and biological settings. Applications explored include the folding thermodynamics of a pseudoknot, the formation of a kissing loop complex, the structure of a hexagonal RNA nanoring, and the unzipping of a hairpin motif. We argue that the model can be used for efficient simulations of the structure of systems with thousands of base pairs, and for the assembly of systems of up to hundreds of base pairs. The source code implementing the model is released for public use.

  2. Determination of the scale of coarse graining in earthquake network

    CERN Document Server

    Abe, Sumiyoshi

    2009-01-01

    In a recent paper [S. Abe and N. Suzuki, Europhys. Lett., 65 (2004) 581], the concept of earthquake network has been introduced in order to describe complexity of seismicity. There, the cell size, which is the scale of coarse graining needed for constructing an earthquake network, has remained as a free parameter. Here, a method is presented for determining it based on the scaling behavior of the network. Quite remarkably, both the exponent of the power-law connectivity distribution and the clustering coefficient are found to approach the respective universal values and remain invariant as the cell size becomes larger than a certain value, $l_*$, which depends on the number of events contained in the analysis, in general. This $l_*$ fixes the scale of coarse graining. Universality of the result is demonstrated for all of the networks constructed from the data independently taken from California, Japan and Iran.

  3. Vesicles and vesicle fusion: coarse-grained simulations

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2010-01-01

    Biological cells are highly dynamic, and continually move material around their own volume and between their interior and exterior. Much of this transport encapsulates the material inside phospholipid vesicles that shuttle to and fro, fusing with, and budding from, other membranes. A feature...... of vesicles that is crucial for this transport is their ability to fuse to target membranes and release their contents to the distal side. In industry, some personal care products contain vesicles to help transport reagents across the skin, and research on drug formulation shows that packaging active...... compounds inside vesicles delays their clearance from the blood stream. In this chapter, we survey the biological role and physico-chemical properties of phospholipids, and describe progress in coarse-grained simulations of vesicles and vesicle fusion. Because coarse-grained simulations retain only those...

  4. Coarse-to-fine region selection and matching

    KAUST Repository

    Yang, Yanchao

    2015-10-15

    We present a new approach to wide baseline matching. We propose to use a hierarchical decomposition of the image domain and coarse-to-fine selection of regions to match. In contrast to interest point matching methods, which sample salient regions to reduce the cost of comparing all regions in two images, our method eliminates regions systematically to achieve efficiency. One advantage of our approach is that it is not restricted to covariant salient regions, which is too restrictive under large viewpoint and leads to few corresponding regions. Affine invariant matching of regions in the hierarchy is achieved efficiently by a coarse-to-fine search of the affine space. Experiments on two benchmark datasets shows that our method finds more correct correspondence of the image (with fewer false alarms) than other wide baseline methods on large viewpoint change. © 2015 IEEE.

  5. Carbon fixation by basalt-hosted microbial communities

    Directory of Open Access Journals (Sweden)

    Beth N Orcutt

    2015-09-01

    Full Text Available Oceanic crust is a massive potential habitat for microbial life on Earth, yet our understanding of this ecosystem is limited due to difficulty in access. In particular, measurements of rates of microbial activity are sparse. We used stable carbon isotope incubations of crustal samples, coupled with functional gene analyses, to examine the potential for carbon fixation on oceanic crust. Both seafloor-exposed and subseafloor basalts were recovered from different mid-ocean ridge and hot spot environments (i.e., the Juan de Fuca Ridge, the Mid-Atlantic Ridge, and the Loihi Seamount and incubated with 13C-labeled bicarbonate. Seafloor-exposed basalts revealed incorporation of 13C-label into organic matter over time, though the degree of incorporation was heterogeneous. The incorporation of 13C into biomass was inconclusive in subseafloor basalts. Translating these measurements into potential rates of carbon fixation indicated that 0.1 – 10 nmol C g-1rock d-1 could be fixed by seafloor-exposed rocks. When scaled to the global production of oceanic crust, this suggests carbon fixation rates of 10^9 – 10^12 g C yr-1, which matches earlier predictions based on thermodynamic calculations. Functional gene analyses indicate that the Calvin cycle is likely the dominant biochemical mechanism for carbon fixation in basalt-hosted biofilms, although the reductive acetyl-CoA pathway and reverse TCA cycle likely play some role in net carbon fixation. These results provide empirical evidence for autotrophy in oceanic crust, suggesting that basalt-hosted autotrophy could be a significant contributor of organic matter in this remote and vast environment.

  6. Carbon fixation by basalt-hosted microbial communities.

    Science.gov (United States)

    Orcutt, Beth N; Sylvan, Jason B; Rogers, Daniel R; Delaney, Jennifer; Lee, Raymond W; Girguis, Peter R

    2015-01-01

    Oceanic crust is a massive potential habitat for microbial life on Earth, yet our understanding of this ecosystem is limited due to difficulty in access. In particular, measurements of rates of microbial activity are sparse. We used stable carbon isotope incubations of crustal samples, coupled with functional gene analyses, to examine the potential for carbon fixation on oceanic crust. Both seafloor-exposed and subseafloor basalts were recovered from different mid-ocean ridge and hot spot environments (i.e., the Juan de Fuca Ridge, the Mid-Atlantic Ridge, and the Loihi Seamount) and incubated with (13)C-labeled bicarbonate. Seafloor-exposed basalts revealed incorporation of (13)C-label into organic matter over time, though the degree of incorporation was heterogeneous. The incorporation of (13)C into biomass was inconclusive in subseafloor basalts. Translating these measurements into potential rates of carbon fixation indicated that 0.1-10 nmol C g(-1) rock d(-1) could be fixed by seafloor-exposed rocks. When scaled to the global production of oceanic crust, this suggests carbon fixation rates of 10(9)-10(12) g C year(-1), which matches earlier predictions based on thermodynamic calculations. Functional gene analyses indicate that the Calvin cycle is likely the dominant biochemical mechanism for carbon fixation in basalt-hosted biofilms, although the reductive acetyl-CoA pathway and reverse TCA cycle likely play some role in net carbon fixation. These results provide empirical evidence for autotrophy in oceanic crust, suggesting that basalt-hosted autotrophy could be a significant contributor of organic matter in this remote and vast environment.

  7. Simulation of Ionic Aggregation and Ion Dynamics in Model Ionomers

    Science.gov (United States)

    Frischknecht, Amalie L.

    2012-02-01

    Ionomers, polymers containing a small fraction of covalently bound ionic groups, are of interest as possible electrolytes in batteries. A single-ion conducting polymer electrolyte would be safer and have higher efficiency than the currently-used liquid electrolytes. However, to date ionomeric materials do not have sufficiently high conductivities for practical application. This is most likely because the ions tend to form aggregates, leading to slow ion transport. A key question is therefore how molecular structure affects the ionic aggregation and ion dynamics. To probe these structure-property relationships, we have performed molecular simulations of a set of recently synthesized poly(ethylene-co-acrylic acid) copolymers and ionomers, with a focus on the morphology of the ionic aggregates. The ionomers have a precise, constant spacing of charged groups, making them ideal for direct comparisons with simulations. Ab initio calculations give insight into the expected coordination of cations with fragments of the ionomers. All-atom molecular dynamics (MD) simulations of the ionomer melt show aggregation of the ionic groups into extended string-like clusters. An extensive set of coarse-grained molecular dynamics simulations extend the results to longer times and larger length scales. The structure factors calculated from the MD simulations compare favorably with x-ray scattering data. Furthermore, the simulations give a detailed picture of the sizes, shapes, and composition of the ionic aggregates, and how they depend on polymer architecture. Implications for ion transport will be discussed. [Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  8. Roman Coarse Ware from Bavaria, Austria and Northern Italy

    Energy Technology Data Exchange (ETDEWEB)

    Fluegel, Ch. [Landesstelle fuer die nichtstaatlichen Museen in Bayern (Germany); Fluegel, E. [Universitaet Erlangen-Nuernberg, Institut fuer Palaontologie (Germany); Haeusler, W. [Technische Universitaet Muenchen, Physik-Department E15 (Germany); Joachimski, M. [Universitaet Erlangen-Nuernberg, Institut fuer Geologie und Mineralogie (Germany); Koller, J.; Baumer, U. [Doerner-Institut (Germany); Wagner, U. [Technische Universitaet Muenchen, Physik-Department E15 (Germany)

    2004-06-15

    This interdisciplinary study focuses on a specific type of Roman coarse ware that was widely distributed in Bavaria, Austria and northern Italy during the 1st half of the 1st century AD. Various physical methods were applied to study the provenance of this characteristic marble tempered blackware and to assess its production techniques. The blackware found in large numbers on the Auerberg and at other sites in southern Germany can be identified as imported from East Tyrol, Austria.

  9. Fuel type characterization based on coarse resolution MODIS satellite data

    OpenAIRE

    Lasaponara R; Lanorte A

    2007-01-01

    Fuel types is one of the most important factors that should be taken into consideration for computing spatial fire hazard and risk and simulating fire growth and intensity across a landscape. In the present study, forest fuel mapping is considered from a remote sensing perspective. The purpose is to delineate forest types by exploring the use of coarse resolution satellite remote sensing MODIS imagery. In order to ascertain how well MODIS data can provide an exhaustive classification of fuel ...

  10. Coarse pointing mechanism assembly for satellite interlink experiment

    Science.gov (United States)

    Maeusli, P. A.; Ivorra, M. T.; Gass, V.; Berthoud, J. F.

    1996-01-01

    Since 1975, MECANEX S.A. has been manufacturing components for solar array drives and mechanisms used in space applications. In 1991, work was started in an early phase C (Engineering Model) on a Coarse Pointing Mechanism Assembly (CPMA) for the Semiconductor-laser Inter-satellite Link EXperiment (SILEX). This paper deals with the history, the evolution, and the lessons learned from taking over a pre-design in 1991 to the delivery of last flight models (FM 5 & 6) in 1995.

  11. Significance of coarse cereals in health and nutrition: a review

    OpenAIRE

    Kaur, Kiran Deep; Jha, Alok; Sabikhi, Latha; A. K. Singh

    2012-01-01

    This review assesses the nutritional attributes of coarse cereals and also their utilization as food and as formulated foods. These cereals are laden with phytochemicals including phenolic acids, tannins, anthocyanins, phytosterols, avenenathramides and policosanols. They possess high antioxidant properties in vitro than staple cereals and fruits by different purported pathways. There are also some anti-nutritional factors that may be reduced by certain processing treatments. Several epidemio...

  12. Crossing barriers in planetesimal formation: The growth of mm-dust aggregates with large constituent grains

    CERN Document Server

    Jankowski, Tim; Kelling, Thorben; Teiser, Jens; Sabolo, Walter; Gutiérrez, Pedro J; Bertini, Ivano; 10.1051/0004-6361/201218984

    2012-01-01

    Collisions of mm-size dust aggregates play a crucial role in the early phases of planet formation. We developed a laboratory setup to observe collisions of dust aggregates levitating at mbar pressures and elevated temperatures of 800 K. We report on collisions between basalt dust aggregates of from 0.3 to 5 mm in size at velocities between 0.1 and 15 cm/s. Individual grains are smaller than 25 \\mum in size. We find that for all impact energies in the studied range sticking occurs at a probability of 32.1 \\pm 2.5% on average. In general, the sticking probability decreases with increasing impact parameter. The sticking probability increases with energy density (impact energy per contact area). We also observe collisions of aggregates that were formed by a previous sticking of two larger aggregates. Partners of these aggregates can be detached by a second collision with a probability of on average 19.8 \\pm 4.0%. The measured accretion efficiencies are remarkably high compared to other experimental results. We at...

  13. Systematic and Simulation-Free Coarse Graining of Polymeric Systems: A Structure-based Study

    Science.gov (United States)

    Yang, Delian; Wang, Qiang

    2015-03-01

    We propose a systematic and simulation-free strategy for coarse graining of multicomponent polymeric systems, where we use the Polymer Reference Interaction Site Model theory, instead of many-chain molecular simulations, to calculate the structure and thermodynamic properties of both the original and coarse-grained (CG) models, and quantitatively examine how the effective CG pair potentials and properties of CG systems vary with the coarse-graining level. Our strategy is general and versatile, is much faster than those using many-chain simulations, and practically solves the transferability problem of coarse graining. As an example, here we apply it to structure-based coarse graining of homopolymer melts, which matches the structure correlations of CG segments between the original and CG systems. Our numerical results clearly show that structure-based coarse graining cannot give thermodynamic consistency between the original and CG systems at any coarse-graining level due to the information loss of coarse graining.

  14. Coarse-graining two-dimensional turbulence via dynamical optimization

    Science.gov (United States)

    Turkington, Bruce; Chen, Qian-Yong; Thalabard, Simon

    2016-10-01

    A model reduction technique based on an optimization principle is employed to coarse-grain inviscid, incompressible fluid dynamics in two dimensions. In this reduction the spectrally-truncated vorticity equation defines the microdynamics, while the macroscopic state space consists of quasi-equilibrium trial probability densities on the microscopic phase space, which are parameterized by the means and variances of the low modes of the vorticity. A macroscopic path therefore represents a coarse-grained approximation to the evolution of a nonequilibrium ensemble of microscopic solutions. Closure in terms of the vector of resolved variables, namely, the means and variances of the low modes, is achieved by minimizing over all feasible paths the time integral of their mean-squared residual with respect to the Liouville equation. The equations governing the optimal path are deduced from Hamilton-Jacobi theory. The coarse-grained dynamics derived by this optimization technique contains a scale-dependent eddy viscosity, modified nonlinear interactions between the low mode means, and a nonlinear coupling between the mean and variance of each low mode. The predictive skill of this optimal closure is validated quantitatively by comparing it against direct numerical simulations. These tests show that good agreement is achieved without adjusting any closure parameters.

  15. High capacitance of coarse-grained carbide derived carbon electrodes

    Science.gov (United States)

    Dyatkin, Boris; Gogotsi, Oleksiy; Malinovskiy, Bohdan; Zozulya, Yuliya; Simon, Patrice; Gogotsi, Yury

    2016-02-01

    We report exceptional electrochemical properties of supercapacitor electrodes composed of large, granular carbide-derived carbon (CDC) particles. Using a titanium carbide (TiC) precursor, we synthesized 70-250 μm sized particles with high surface area and a narrow pore size distribution. Electrochemical cycling of these coarse-grained powders defied conventional wisdom that a small particle size is strictly required for supercapacitor electrodes and allowed high charge storage densities, rapid transport, and good rate handling ability. The material showcased capacitance above 100 F g-1 at sweep rates as high as 250 mV s-1 in organic electrolyte. 250-1000 micron thick dense CDC films with up to 80 mg cm-2 loading showed superior areal capacitances. The material significantly outperformed its activated carbon counterpart in organic electrolytes and ionic liquids. Furthermore, large internal/external surface ratio of coarse-grained carbons allowed the resulting electrodes to maintain high electrochemical stability up to 3.1 V in ionic liquid electrolyte. In addition to presenting novel insights into the electrosorption process, these coarse-grained carbons offer a pathway to low-cost, high-performance implementation of supercapacitors in automotive and grid-storage applications.

  16. Moving Beyond Watson-Crick Models of Coarse Grained DNA

    Science.gov (United States)

    Dorfman, Kevin; Linak, Margaret; Tourdot, Richard

    2012-02-01

    DNA structure possesses several levels of complexity, ranging from the sequence of bases (primary structure) to base pairing (secondary structure) to its three-dimensional shape (tertiary structure) and can produce a wide variety of conformations in addition to canonical double stranded DNA. By including non-Watson-Crick interactions in a coarse-grained model, we developed a system that not only can capture the traditional B-form double helix, but also can adopt a wide variety of other DNA conformations. In our experimentally parameterized, coarse-grained DNA model we are able to reproduce the microscopic features of double-stranded DNA without the need for explicit constraints and capture experimental melting curves for a number of short DNA hairpins. We demonstrate the utility of the model by simulating more complex tertiary structures such as the folding of the thrombin aptamer, which includes G-quartets, and strand invasion during triplex formation. Our results highlight the importance of non-canonical interactions in DNA coarse- grained models.

  17. Geochemistry of Two Types of Basalts in the Emeishan Basaltic Province: Evidence for Mantle Plume-Lithosphere Interaction

    Institute of Scientific and Technical Information of China (English)

    张招崇; 王福生

    2002-01-01

    Based on the temporal-spatial distribution and geochemical characteristics, the Emeishan basalts can be divided into two types: high-P2O-TiO2 basalt (HPT) and low-P2O5-TiO2 basalt (LPT), which differ distinctly in geochemistry: the LPTs are characterized by relatively high abundances of MgO, total FeO and P2O5 and compatible elements (Cr, Ni, Sc), and relatively low contents of moderately compatible elements (V, Y, Yb, Co), LREE and other incompatible elements compared with the HPT. On the diagrams of trace element ratios, they are plotted on an approximately linear mixing line between depleted and enriched mantle sources, suggesting that these two types of basalts resulted from interactions of varying degrees between mantle plume and lithospheric mantle containing such volatile-rich minerals as amphibole and apatite. The source region of the LPT involves a smaller proportion of lithospheric components, while that of the HTP has a larger proportion of lithospheric components. Trachyte is generated by partial melting of the basic igneous rocks at the base of the lower continental crust. Both the two types of magmas underwent certain crystal fractionation and contamination of the lower crust at high-level magma chambers and en route to the surface.

  18. Eruption and emplacement of flood basalt. An example from the large-volume Teepee Butte Member, Columbia River Basalt Group

    Energy Technology Data Exchange (ETDEWEB)

    Reidel, S.P. (Washington State Univ., Pullman (United States)); Tolan, T.L. (Portland State Univ., OR (United States))

    1992-12-01

    Flows of the Teepee Butte Member, Grande Ronde Basalt, issued from a vent system in southeastern Washington, northeastern Oregon, and western Idaho. Three distinct basalt flows were erupted: the Limekiln Rapids flow, the Joseph Creek flow, and the Pruitt Draw flow. Together these mappable flows cover more than 52,000 km[sup 2] and have a volume exceeding 5,000 km[sup 3]. A portion of the vent system for the Joseph Creek flow is exposed in cross section in Joseph Canyon, Washington; it is one of the best preserved Columbia River Basalt Group vent complexes known. The vent complex is about 1 km in cross section, 30 m high, and composed of deposits characteristic of Hawaiian-type volcanism. The vent is asymmetrical; the eastern rampart consists of intercalated pyroclastic deposits and thin pahoehoe flows; the western rampart is composed wholly of pahoehoe flows. Flows of the Teepee Butte Member are compositionally homogeneous and were emplaced as sheet flows, each having several local flow units. Our study supports the importance of linear vent systems and the westward Palouse Slope, along with the large-volume lava flows, in controlling the distribution of Columbia River Basalt Group flows. Other factors, including the number of active fissure segments and topography, modified the shape of the flows and the number of flow units. 45 refs., 19 figs., 2 tabs.

  19. Zr and Nb partition coefficients - Implications for the genesis of mare basalts, KREEP, and sea floor basalts

    Science.gov (United States)

    Mccallum, I. S.; Charette, M. P.

    1978-01-01

    The distribution coefficients of Zr and Nb have been found between armalcolite, ilmenite, clinopyroxene, rutile, plagioclase, and a coexisting high-Ti mare basalt melt in the 1105-1128 C temperature range. Henry's Law is not broken over the compositional range evaluated. The distribution coefficients of clinopyroxene are strongly dependent on melt and crystal compositions. The Al2O3 activity in the melt is a strong controlling parameter. It is concluded that: (1) Apollo 11 (low K) and Apollo 17 high-Ti mare basalts may have been generated by the partial melting of an ilmenite-rich cumulate, (2) Apollo 11 (high K) basalts may have been generated by a small amount of partial melting of a more fractionated ilmenite-rich cumulate, (3) KREEP magmas may have been formed as residual melts produced by fractional crystallization of the lunar magma ocean, and (4) anomalous (type II) MOR basalts may have been generated by small degrees of partial melting of a relatively undepleted mantle with clinopyroxene remaining in the residium.

  20. Logical Constraints on Judgement Aggregation

    NARCIS (Netherlands)

    Hees, Martin van; Pauly, Marc

    2006-01-01

    Logical puzzles like the doctrinal paradox raise the problem of how to aggregate individual judgements into a collective judgement, or alternatively, how to merge collectively inconsistent knowledge bases. In this paper, we view judgement aggregation as a function on propositional logic valuations,

  1. Exciton dynamics in molecular aggregates

    NARCIS (Netherlands)

    Augulis, R.; Pugžlys, A.; Loosdrecht, P.H.M. van; Pugzlys, A

    2006-01-01

    The fundamental aspects of exciton dynamics in double-wall cylindrical aggregates of cyanine dyes are studied by means of frequency resolved femtosecond pump-probe spectroscopy. The collective excitations of the aggregates, resulting from intermolecular dipole-dipole interactions have the characteri

  2. Aggregate resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Gessel, S.F. van; Veldkamp, J.G.

    2005-01-01

    We have built a 3D lithological model of the Netherlands, for the purpose of mapping on-land aggregate resources down to 50 m below the surface. The model consists of voxel cells (1000 · 1000 · 1 m), with lithological composition and aggregate content estimates as primary attributes. These attribute

  3. Optical monitoring of particle aggregates

    Institute of Scientific and Technical Information of China (English)

    John Gregory

    2009-01-01

    Methods for monitoring particle aggregation are briefly reviewed. Most of these techniques are based on some form of light scattering and may be greatly dependent on the optical properties of aggregates, which are not generally known. As fractal aggregates grow larger their density can become very low and this has important practical consequences for light scattering. For instance, the scattering coefficient may be much less than for solid objects, which means that the aggregates can appear much smaller than their actual size by a light transmission method. Also, for low-density objects, a high proportion of the scattered light energy is within a small angle of the incident beam, which may also be relevant for measurements with aggregates.Using the 'turbidity fluctuation' technique as an example, it is shown how the apparent size of hydroxide flocs depends mainly on the included impurity particles, rather than the hydroxide precipitate itself. Results using clay suspensions with hydrolyzing coagulants and under are discussed.

  4. Molecular aggregation of humic substances

    Science.gov (United States)

    Wershaw, R. L.

    1999-01-01

    Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into amphiphilic molecules, that is, molecules that consist of separate hydrophobic (nonpolar) and hydrophilic (polar) parts. The nonpolar parts of the molecules are composed of relatively unaltered segments of plant polymers and the polar parts of carboxylic acid groups. These amphiphiles form membrane-like aggregates on mineral surfaces and micelle-like aggregates in solution. The exterior surfaces of these aggregates are hydrophilic, and the interiors constitute separate hydrophobic liquid-like phases.

  5. DRAG ON SUBMICRON NANOPARTICLE AGGREGATES

    Institute of Scientific and Technical Information of China (English)

    F.; Einar; Kruis

    2005-01-01

    A new procedure was developed for estimating the effective collision diameter of an aggregate composed of primary particles of any size. The coagulation coefficient of two oppositely charged particles was measured experimentally and compared with classic Fuchs theory, including a new method to account for particle non-sphericity. A second set of experiments were performed on well-defined nanoparticle aggregates at different stages of sintering, i.e. from the aggregate to the fully sintered stage. Here, electrical mobility was used to characterize the particle drag. The aggregates are being built from two different size-fractionated nanoparticle aerosols, the non-aggregated particles are discarded by an electrofilter and then they are passed through a furnace at concentrations low enough not to induce coagulation.

  6. Immunogenicity of Therapeutic Protein Aggregates.

    Science.gov (United States)

    Moussa, Ehab M; Panchal, Jainik P; Moorthy, Balakrishnan S; Blum, Janice S; Joubert, Marisa K; Narhi, Linda O; Topp, Elizabeth M

    2016-02-01

    Therapeutic proteins have a propensity for aggregation during manufacturing, shipping, and storage. The presence of aggregates in protein drug products can induce adverse immune responses in patients that may affect safety and efficacy, and so it is of concern to both manufacturers and regulatory agencies. In this vein, there is a lack of understanding of the physicochemical determinants of immunological responses and a lack of standardized analytical methods to survey the molecular properties of aggregates associated with immune activation. In this review, we provide an overview of the basic immune mechanisms in the context of interactions with protein aggregates. We then critically examine the literature with emphasis on the underlying immune mechanisms as they relate to aggregate properties. Finally, we highlight the gaps in our current understanding of this issue and offer recommendations for future research. PMID:26869409

  7. Dye Aggregation in Ink Jet

    Institute of Scientific and Technical Information of China (English)

    Thomas Paul; Sarfraz Hussain

    2004-01-01

    Dye aggregation has long been recognised as a key factor in performance, and this is no less so in ink jet applications. The aggregation state was shown to be important in many different areas ranging from the use of dyes in photodynamic therapies all the way to colorants for dying of fabrics. Therefore different methods to investigate dye association qualitatively and quantitatively were developed. A simple procedure to study aggregation could be a useful tool to characterise dyes for ink jet printing. It is critically reviewed the methods used to study dye aggregation, and discussed some of the main conclusions. This will be illustrated by examples of ink jet dye aggregation and its study in aqueous and ink systems. The results are used to correlate the solution behaviour of dyes with their print performance.

  8. Experimental Research on Compounding Concrete with Recycled Aggregates%用再生骨料配制混凝土的试验研究

    Institute of Scientific and Technical Information of China (English)

    张秀芳; 何更新; 赵霄龙

    2011-01-01

    Through the replacement of partial or the whole natural aggregates with recycled coarse aggregate and recycled fine aggregate, the influences of replacement ratios of recycled coarse aggregate and recycled fine aggregate on concrete performance have been investigated. The results showed that with the increasing of replacement ratio of recycled aggregate, the water demand increasing linearly, and the compressive strength and the bulk density reducing. It is pointed out that the replacement ratio of grade I recycled aggregate has no limit, but the replacement ratio of grade II and grade III recycled aggregate should be controlled in 50% for C30 and C40 concrete. Moreover the recycled coarse aggregate and recycled fine aggregate should not be used together in the concrete.%通过分别采用再生粗骨料和再生细骨料取代部分或全部天然砂石骨料,研究再生粗(细)骨料取代率对混凝土性能的影响.试验结果表明,随着再生粗(细)骨料取代率的提高,混凝土用水量呈线性增加,而抗压强度呈线性下降,表观密度也随之下降.最后指出Ⅰ类再生骨料取代率可不受限制,对于C30,C40混凝土Ⅱ,Ⅲ类宜在50%以内,且不宜同时掺再生粗骨料和再生细骨料.

  9. 再生骨料特性对再生混凝土强度和碳化性能的影响%Influence of Recycled Aggregate on Strength and Anti-carbonation Properties of Recycled Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    崔正龙; 路沙沙; 汪振双

    2012-01-01

    Influence of surface mortar strength and adhesive rate around coarse aggregate on recycled aggregate concrete(RAC) were investigated. Concrete of different strength were prepared with recycled aggregate of different surface mortar strength and adhesive rate to investigate their properties. It has been shown that, for low strength recycled aggregate concrete with higher strength ordinary concrete, the strength of recycled aggregate concrete and ordinary concrete are nearly the same, and the effect of surface mortar strength and adhesive rate around coarse aggregate on recycled aggregate concrete is low, while the carbonization depth of recycled aggregate concrete is higher than that of ordinary concrete; on the other hand, for recycled aggregate concrete prepared by low strength ordinary concrete, there are great differences between recycled aggregate concrete and ordinary concrete, the effect of surface mortar strength and adhesive rate around coarse aggregate on recycled aggregate concrete is significant and carbonization depth is increasing.%为了评价再生骨料表面砂浆的强度及附着率对再生混凝土性能的影响,以再生骨科表面不同的砂浆强度及附着率为变量,配制了不同强度等级的再生骨料混凝土,通过对比性强度试验和碳化试验评价了再生混凝土内部存在的2个界面过渡区与混凝土性能的关系.结果表明:以高强度原生混凝土为再生骨料配制相对较低强度等级的再生骨料混凝土时,其强度与普通混凝土几乎相同,再生骨料表面砂浆的强度及附着率对再生骨料混凝土强度影响不大,但碳化深度有所增大;以相对较低强度原生混凝土为再生骨料配制同强度等级以上的再生骨科混凝土时,其强度与普通混凝土相差较大,再生骨料表面砂浆的强度及附着率对再生混凝土强度影响较大,碳化深度也相应增大.

  10. Use of recycled fine aggregate in concretes with durable requirements.

    Science.gov (United States)

    Zega, Claudio Javier; Di Maio, Angel Antonio

    2011-11-01

    The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete. PMID:21775123

  11. Utilization of Recycled Concrete Aggregates in Stone Mastic Asphalt Mixtures

    Directory of Open Access Journals (Sweden)

    Mohammad Saeed Pourtahmasb

    2014-01-01

    Full Text Available Recycled concrete aggregate (RCA is considered as one of the largest wastes in the entire world which is produced by demolishing concrete structures such as buildings, bridges, and dams. It is the intention of scientists and researchers, as well as people in authority, to explore waste material recycling for environmental and economic advantages. The current paper presents an experimental research on the feasibility of reusing RCA in stone mastic asphalt (SMA mixtures as a partial replacement of coarse and fine aggregates. The engineering properties of SMA mixtures containing RCA have been evaluated for different percentages of binders based on the Marshall mix design method. The outcomes were statistically analyzed using two-factor analysis of variance (ANOVA. Test results revealed that the performance of SMA mixtures is affected by RCA due to higher porosity and absorption of RCA in comparison with virgin granite aggregates. However, the engineering properties of SMA mixtures containing a particular amount of RCA showed the acceptable trends and could satisfy the standard requirements. Moreover, to achieve desirable performance characteristics, more caution should be made on properties of SMA mixtures containing RCA.

  12. Magnetic mineralogy of pyroxenite xenoliths from Hannuoba basalts, northern North China Craton: Implications for magnetism in the continental lower crust

    Science.gov (United States)

    Li, Zhiyong; Zheng, Jianping; Zeng, Qingli; Liu, Qingsheng; Griffin, W. L.

    2014-02-01

    Studies of the petrology, mineral chemistry, and rock magnetic properties of nine pyroxenite xenoliths from Hannuoba basalts, northern North China Craton, have been made to determine the magnetization signature of the continental lower crust. These pyroxenites are weakly magnetic with low average susceptibility (χ) and saturation isothermal remanent magnetization (Mrs) of 39.59 × 10-8 m3 kg-1 and 12.05 × 10-3 Am2 kg-1, respectively. The magnetic minerals are mainly magnetite, pyrrhotite, and Fe-rich spinel, which significantly contribute to χ and natural remanent magnetization. Magnetite occurs as interstitial microcrystals together with zeolite aggregates, indicating a secondary origin in a supergene environment. In contrast, pyrrhotite and Fe-rich spinel were formed prior to the xenoliths' ascent to the surface, as evidenced by their dominant occurrence as tiny inclusions and thin exsolution lamellae in pyroxene. The Fe-rich spinel has ~ 50% mole fraction of Fe3O4 and corresponds to the strongest magnetization, and its coexistence with Mg-rich spinel implies a reheating event due to the underplating of basaltic magma. Besides, armalcolite and ilmenite were found in the reaction rims between xenoliths and the basalt, but they contribute little to the whole rock magnetization. However, these pyroxenite xenoliths would be nonmagnetic at in situ depths, as well as peridotite and mafic granulite xenoliths derived from the crust-mantle transition zone (~ 32-42 km). Therefore, we suggest the limiting depth of magnetization at the boundary between weakly magnetic deep-seated (lower crust and upper mantle) xenoliths and strongly magnetic Archean granulite facies rocks (~ 32 km) in Hannuoba, northern North China Craton.

  13. Efficient coarse simulation of a growing avascular tumor

    Science.gov (United States)

    Kavousanakis, Michail E.; Liu, Ping; Boudouvis, Andreas G.; Lowengrub, John; Kevrekidis, Ioannis G.

    2013-01-01

    The subject of this work is the development and implementation of algorithms which accelerate the simulation of early stage tumor growth models. Among the different computational approaches used for the simulation of tumor progression, discrete stochastic models (e.g., cellular automata) have been widely used to describe processes occurring at the cell and subcell scales (e.g., cell-cell interactions and signaling processes). To describe macroscopic characteristics (e.g., morphology) of growing tumors, large numbers of interacting cells must be simulated. However, the high computational demands of stochastic models make the simulation of large-scale systems impractical. Alternatively, continuum models, which can describe behavior at the tumor scale, often rely on phenomenological assumptions in place of rigorous upscaling of microscopic models. This limits their predictive power. In this work, we circumvent the derivation of closed macroscopic equations for the growing cancer cell populations; instead, we construct, based on the so-called “equation-free” framework, a computational superstructure, which wraps around the individual-based cell-level simulator and accelerates the computations required for the study of the long-time behavior of systems involving many interacting cells. The microscopic model, e.g., a cellular automaton, which simulates the evolution of cancer cell populations, is executed for relatively short time intervals, at the end of which coarse-scale information is obtained. These coarse variables evolve on slower time scales than each individual cell in the population, enabling the application of forward projection schemes, which extrapolate their values at later times. This technique is referred to as coarse projective integration. Increasing the ratio of projection times to microscopic simulator execution times enhances the computational savings. Crucial accuracy issues arising for growing tumors with radial symmetry are addressed by

  14. Investigating the explosivity of shallow sub-aqueous basaltic eruptions

    Science.gov (United States)

    Murtagh, R.; White, J. D. L.

    2009-04-01

    Volcanic eruptions produce pyroclasts containing vesicles, clearly implying exsolution of volatiles from the magma has occurred. Our aim is to understand the textural characteristics of vesiculated clasts as a quantitative indicator of the eruptive behaviour of a volcano. Assessing water's role in volatile degassing and outgassing has been and is being well documented for terrestrial eruptions; the same cannot be said, however, for their shallow subaqueous counterparts. The eruptive behaviour of Surtseyan volcanoes, which include both subaqueous and subaerial phases (for example, the type-location Surtsey, Iceland in 1963) is under investigation here and for good reason. Volcanic eruptions during which water and basaltic magma come into contact appear to ignite violent eruptions of many of the small "monogenetic" volcanoes so abundant on Earth. A key problem remains that detailed conditions of water-magma interactions are not yet fully understood. Field samples obtained from exposed sequences deposited originally in a subaqueous environment allow for the necessary analysis of lapilli. With the aid of experimental data, mathematical modelling and terrestrial analogues the ambition is to unravel volatile degassing, ascent histories and fragmentation processes, allowing us ultimately to identify both the role water plays in the explosivity of shallow subaqueous eruptions, and the rise history of magma to the point of interaction. The first site, Pahvant Butte is located in southwest Utah, U.S. It is a well preserved tuff cone overlying a subaqueously deposited mound of glassy ash composed of sideromelane and tachylite. It was erupted under ~85m of water into Lake Bonneville approximately 15,300 years ago. Our focus is on samples collected from a well-bedded, broadly scoured coarse ash and lapilli lithofacies on the eastern flank of the edifice. Vesicularity indices span from 52.6% - 60.8%, with very broad vesicularity ranges, 20.6% - 81.0% for one extreme sample. The

  15. Orthogonal flexible Rydberg aggregates

    CERN Document Server

    Leonhardt, K; Rost, J M

    2015-01-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable non-adiabatic effects. A joint exciton/motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of non-adiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K.~Leonhardt {\\it et al.}, Phys.~Rev.~Lett. {\\bf 113} 223001 (2014)]. In this article we discuss the underlying complex dynamics in detail, characterise the ...

  16. Perspectives on Preference Aggregation.

    Science.gov (United States)

    Regenwetter, Michel

    2009-07-01

    For centuries, the mathematical aggregation of preferences by groups, organizations, or society itself has received keen interdisciplinary attention. Extensive theoretical work in economics and political science throughout the second half of the 20th century has highlighted the idea that competing notions of rational social choice intrinsically contradict each other. This has led some researchers to consider coherent democratic decision making to be a mathematical impossibility. Recent empirical work in psychology qualifies that view. This nontechnical review sketches a quantitative research paradigm for the behavioral investigation of mathematical social choice rules on real ballots, experimental choices, or attitudinal survey data. The article poses a series of open questions. Some classical work sometimes makes assumptions about voter preferences that are descriptively invalid. Do such technical assumptions lead the theory astray? How can empirical work inform the formulation of meaningful theoretical primitives? Classical "impossibility results" leverage the fact that certain desirable mathematical properties logically cannot hold in all conceivable electorates. Do these properties nonetheless hold true in empirical distributions of preferences? Will future behavioral analyses continue to contradict the expectations of established theory? Under what conditions do competing consensus methods yield identical outcomes and why do they do so? PMID:26158988

  17. Eco-friendly porous concrete using bottom ash aggregate for marine ranch application.

    Science.gov (United States)

    Lee, Byung Jae; Prabhu, G Ganesh; Lee, Bong Chun; Kim, Yun Yong

    2016-03-01

    This article presents the test results of an investigation carried out on the reuse of coal bottom ash aggregate as a substitute material for coarse aggregate in porous concrete production for marine ranch applications. The experimental parameters were the rate of bottom ash aggregate substitution (30%, 50% and 100%) and the target void ratio (15%, 20% and 25%). The cement-coated granular fertiliser was substituted into a bottom ash aggregate concrete mixture to improve marine ranch applications. The results of leaching tests revealed that the bottom ash aggregate has only a negligible amount of the ten deleterious substances specified in the Ministry of Environment - Enforcement Regulation of the Waste Management Act of Republic Korea. The large amount of bubbles/air gaps in the bottom ash aggregate increased the voids of the concrete mixtures in all target void ratios, and decreased the compressive strength of the porous concrete mixture; however, the mixture substituted with 30% and 10% of bottom ash aggregate and granular fertiliser, respectively, showed an equal strength to the control mixture. The sea water resistibility of the bottom ash aggregate substituted mixture was relatively equal to that of the control mixture, and also showed a great deal of improvement in the degree of marine organism adhesion compared with the control mixture. No fatality of fish was observed in the fish toxicity test, which suggested that bottom ash aggregate was a harmless material and that the combination of bottom ash aggregate and granular fertiliser with substitution rates of 30% and 10%, respectively, can be effectively used in porous concrete production for marine ranch application. PMID:26687102

  18. Eco-friendly porous concrete using bottom ash aggregate for marine ranch application.

    Science.gov (United States)

    Lee, Byung Jae; Prabhu, G Ganesh; Lee, Bong Chun; Kim, Yun Yong

    2016-03-01

    This article presents the test results of an investigation carried out on the reuse of coal bottom ash aggregate as a substitute material for coarse aggregate in porous concrete production for marine ranch applications. The experimental parameters were the rate of bottom ash aggregate substitution (30%, 50% and 100%) and the target void ratio (15%, 20% and 25%). The cement-coated granular fertiliser was substituted into a bottom ash aggregate concrete mixture to improve marine ranch applications. The results of leaching tests revealed that the bottom ash aggregate has only a negligible amount of the ten deleterious substances specified in the Ministry of Environment - Enforcement Regulation of the Waste Management Act of Republic Korea. The large amount of bubbles/air gaps in the bottom ash aggregate increased the voids of the concrete mixtures in all target void ratios, and decreased the compressive strength of the porous concrete mixture; however, the mixture substituted with 30% and 10% of bottom ash aggregate and granular fertiliser, respectively, showed an equal strength to the control mixture. The sea water resistibility of the bottom ash aggregate substituted mixture was relatively equal to that of the control mixture, and also showed a great deal of improvement in the degree of marine organism adhesion compared with the control mixture. No fatality of fish was observed in the fish toxicity test, which suggested that bottom ash aggregate was a harmless material and that the combination of bottom ash aggregate and granular fertiliser with substitution rates of 30% and 10%, respectively, can be effectively used in porous concrete production for marine ranch application.

  19. Mechanical characteristics of fused cast basalt tube encased in steel pipe for protecting steel surface

    Institute of Scientific and Technical Information of China (English)

    Jee-Seok WANG; Jong-Do KIM; Hee-Jong YOON

    2009-01-01

    Because of the various excellent characteristics of cast basalt materials, such as, anti-corrosion, anti-wearing, good hardness, high chemical stability, of which steel may not possess, the steel-basalt composite pipes are used in severe environments for compensating the defects of steel. The limit of bending moment with which steel-basalt composite pipe may safely endure was calculated and the limit curvature of the composite pipe in the safe range was presented. The application temperature of steel-basalt pipe was examined due to a different coefficient among basalt, mortar and mild steel.

  20. Aqueous Alteration of Basalts: Earth, Moon, and Mars

    Science.gov (United States)

    Ming, Douglas W.

    2007-01-01

    The geologic processes responsible for aqueous alteration of basaltic materials on Mars are modeled beginning with our knowledge of analog processes on Earth, i.e., characterization of elemental and mineralogical compositions of terrestrial environments where the alteration and weathering pathways related to aqueous activity are better understood. A key ingredient to successful modeling of aqueous processes on Mars is identification of phases that have formed by those processes. The purpose of this paper is to describe what is known about the elemental and mineralogical composition of aqueous alteration products of basaltic materials on Mars and their implications for specific aqueous environments based upon our knowledge of terrestrial systems. Although aqueous alteration has not occurred on the Moon, it is crucial to understand the behaviors of basaltic materials exposed to aqueous environments in support of human exploration to the Moon over the next two decades. Several methods or indices have been used to evaluate the extent of basalt alteration/weathering based upon measurements made at Mars by the Mars Exploration Rover (MER) Moessbauer and Alpha Particle X-Ray Spectrometers. The Mineralogical Alteration Index (MAI) is based upon the percentage of total Fe (Fe(sub T)) present as Fe(3+) in alteration products (Morris et al., 2006). A second method is the evaluation of compositional trends to determine the extent to which elements have been removed from the host rock and the likely formation of secondary phases (Nesbitt and Young, 1992; Ming et al., 2007). Most of the basalts that have been altered by aqueous processes at the two MER landing sites in Gusev crater and on Meridiani Planum have not undergone extensive leaching in an open hydrolytic system with the exception of an outcrop in the Columbia Hills. The extent of aqueous alteration however ranges from relatively unaltered to pervasively altered materials. Several experimental studies have focused upon

  1. Investigation on mechanical properties of basalt composite fabrics (experiment study

    Directory of Open Access Journals (Sweden)

    Talebi Mazraehshahi H.

    2010-06-01

    Full Text Available To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1. Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2. Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3. Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4. Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one

  2. Investigation on mechanical properties of basalt composite fabrics (experiment study)

    Science.gov (United States)

    Talebi Mazraehshahi, H.; Zamani, H.

    2010-06-01

    To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced and mechanical behaviors of this material investigated from view point of testing. For this study two type of fabric with different thickness used. Comparison between this composite reinforcement with popular reinforcement as carbon, glass, kevlar performed. To determine mechanical properties of epoxy based basalt fabric following test procedure performed : 1). Tensile testing according to ASTM D3039 in 0° and 90° direction to find ultimate strength in tension and shear, modulus of elasticity, elangation and ultimate strain. 2). Compression testing according to EN 2850 ultimate compression strength and maximum deformation under compression loading. 3). Shear testing according to ASTM D3518-94 to find in plane shear response of polymer matrix composites materials. 4). Predict flexural properties of sandwich construction which manufactured from basalt facing with PVC foam core according to ASTM C393-94. Material strength properties must be based on enough tests of material to meet the test procedure specifications [1]. For this reason six specimens were manufactured for testing and the tests were performed on them using an INSTRON machine model 5582. In the study, the effect of percent of resin in basalt reinforced composite was investigated. Also the weights of the ballast based composites with different percent of resin were measured with conventional composites. As the weight is an important parameter in aerospace industry when the designer wants to replace one material with

  3. Similarities in basalt and rhyolite lava flow emplacement processes

    Science.gov (United States)

    Magnall, Nathan; James, Mike; Tuffen, Hugh; Vye-Brown, Charlotte

    2016-04-01

    Here we use field observations of rhyolite and basalt lava flows to show similarities in flow processes that span compositionally diverse lava flows. The eruption, and subsequent emplacement, of rhyolite lava flows is currently poorly understood due to the infrequency with which rhyolite eruptions occur. In contrast, the emplacement of basaltic lava flows are much better understood due to very frequent eruptions at locations such as Mt Etna and Hawaii. The 2011-2012 eruption of Cordón Caulle in Chile enabled the first scientific observations of the emplacement of an extensive rhyolite lava flow. The 30 to 100 m thick flow infilled a topographic depression with a negligible slope angle (0 - 7°). The flow split into two main channels; the southern flow advanced 4 km while the northern flow advanced 3 km before stalling. Once the flow stalled the channels inflated and secondary flows or breakouts formed from the flow front and margins. This cooling rather than volume-limited flow behaviour is common in basaltic lava flows but had never been observed in rhyolite lava flows. We draw on fieldwork conducted at Cordón Caulle and at Mt Etna to compare the emplacement of rhyolite and basaltic flows. The fieldwork identified emplacement features that are present in both lavas, such as inflation, breakouts from the flow font and margins, and squeeze-ups on the flow surfaces. In the case of Cordón Caulle, upon extrusion of a breakout it inflates due to a combination of continued lava supply and vesicle growth. This growth leads to fracturing and breakup of the breakout surface, and in some cases a large central fracture tens of metres deep forms. In contrast, breakouts from basaltic lava flows have a greater range of morphologies depending on the properties of the material in the flows core. In the case of Mt Etna, a range of breakout morphologies are observed including: toothpaste breakouts, flows topped with bladed lava as well as breakouts of pahoehoe or a'a lava. This

  4. Susceptibility of coarse-textured soils to soil erosion by water in the tropics

    International Nuclear Information System (INIS)

    The application of soil physics for the evaluation of factors of soil erosion in the tropics received considerable attention in the last four decades. In Nigeria, physical characteristics of rainfall such as drop size and drop-size distribution, rainfall intensity at short intervals and kinetic energy of rainfall were evaluated using different methods. Thus, compound erosivity indices were evaluated which showed a similar trend in annual rainfall erosivity with annual rainfall amounts. Attempts have also been made to use geostatistical tools and fractal theory to describe temporal variability in rainfall erosivity. High erosivity aggravates the vulnerability of coarse-textured soils to erosion. These soils, high in sand content were poorly aggregated and structurally weak. Thus, they were easily detached and transported by runoff. Long-term data are needed to describe factors of soil erosion in the tropics but quite often, equipment are not available or poorly maintained where available such that useful data are not collected. A greater cooperation of pure physicists, soil physicists and engineers in the developing nations is needed to improve or design equipment and methods for the characterization of factors of soil erosion in the tropics. (author)

  5. Surface modification of basalt with silane coupling agent on asphalt mixture moisture damage

    Energy Technology Data Exchange (ETDEWEB)

    Min, Yahong; Fang, Ying; Huang, Xiaojun; Zhu, Yinhui; Li, Wensheng [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Yuan, Jianmin [College of Materials Engineering, Hunan University, Changsha, 410082 (China); Tan, Ligang [College of Mechanical and Vehicle Engineering, Hunan University, Changsha, 410082 (China); Wang, Shuangyin [State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China); Wu, Zhenjun, E-mail: wooawt@163.com [College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082 (China)

    2015-08-15

    Graphical abstract: - Highlights: • A new silane coupling agent was synthesized based on KH570. • Basalt surface was modified using the new silane coupling agent. • Chemical bond between basalt and the new silane coupling agent was formed. • Asphalt mixture which used modified basalt show superior water stability. - Abstract: A new silane coupling agent was synthesized based on γ-(methacryloyloxy) propyltrimethoxysilane (KH570). The surface of basalt rocks was modified by KH570 and the new silane coupling agent (NSCA), and the interfacial interaction between silane coupling agent and basalt was also studied. Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis showed that the silane coupling agent molecule bound strongly with basalt rocks. Scanning electronic microscopy (SEM) observation showed that a thin layer of coupling agent was formed on the surface of modified basalt. The boiling test and immersion Marshall test confirmed that the moisture sensitivity of basalt modified with the new silane coupling agent increased more significantly than that untreated and treated with KH570. The Retained Marshall Strength of basalt modified with the new coupling agent increased from 71.74% to 87.79% compared with untreated basalt. The results indicated that the new silane coupling agent played an important role in improving the interfacial performance between basalt and asphalt.

  6. Automated interpretation of nuclear and electrical well loggings for basalt characterization (case study from southern Syria).

    Science.gov (United States)

    Asfahani, J; Abdul Ghani, B

    2012-10-01

    Nuclear well logging, including natural gamma ray, density and neutron-porosity techniques are used with electrical well logging of long and short normal techniques in order to characterize the large extended basaltic areas in southern Syria. Four kinds of basalt have been identified: hard massive basalt, hard basalt, pyroclastic basalt and the alteration basalt products, clay, based on a statistical analysis approach with the threshold concept. The statistical conditions for such basalt characterization have been programmed in the present research to automatically interpret the well logging data for establishing and predicting the lithological cross-section of the studied well. A specific computer program has been written in Delphi for such purposes. The program is flexible and it can be used for other well logging applications by changing the statistical conditions and the well logging parameters. The program has been successfully tested on the Kodanah well logging data in southern Syria.

  7. Basalt characterization by means of nuclear and electrical well logging techniques. Case study from Southern Syria.

    Science.gov (United States)

    Asfahani, Jamal

    2011-03-01

    Nuclear well logging, including natural gamma ray, density, and neutron-porosity techniques are used with electrical well logging of long and short normal techniques to characterize the basaltic areas largely extended in Southern Syria. Statistical analysis approach with the threshold concept has been adapted for such characterization, where four kinds of basalt have been identified: very hard basalt, hard basalt, fractured basalt, and basalt alteration products. The spectrometric gamma technique has also been applied on the retrieved rock samples in order to determine the radioactive content (eU, eTh, and K%) of the basaltic section in the study area. No radioactive anomalies have been detected, the radioactive values are normal and in the expected range.

  8. COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway

    Science.gov (United States)

    Cepuritis, Rolands; Willy Danielsen, Svein

    2014-05-01

    COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway Rolands Cepuritis, Norcem/NTNU and Svein Willy Danielsen, SINTEF Aggregate production is a mining operation where no purification of the "ore" is necessary. Still it is extremely rare that an aggregate production plant is operating on the basis of zero-waste concept. This is since historically the fine crushed aggregate (particles with a size of less than 2, 4 or sometimes 8 mm) has been regarded as a by-product or waste of the more valuable coarse aggregate production. The reason is that the crushed coarse aggregates can easily replace coarse rounded natural stones in almost any concrete composition; while, the situation with the sand is different. The production of coarse aggregate normally yields fine fractions with rough surface texture, flaky or elongated particles an inadequate gradation. When such a material replaces smooth and rounded natural sand grains in a concrete mix, the result is usually poor and much more water and cement has to be used to achieve adequate concrete flow. The consequences are huge stockpiles of the crushed fine fractions that can't be sold (mass balance problems) for the aggregate producers, sustainability problems for the whole industry and environmental issues for society due to dumping and storing of the fine co-generated material. There have been attempts of utilising the material in concrete before; however, they have mostly ended up in failure. There have been attempts to adjust the crushed sand to the properties of the natural sand, which would still give a lot of waste, especially if the grading would have to be adjusted and the high amounts of fines abundantly present in the crushed sand would have to be removed. Another fundamental reason for failure has been that historically such attempts have mainly ended up in a research carried out by people (both industrial and academic) with aggregate background (= parties willing to find market

  9. Rapid solubility and mineral storage of CO2 in basalt

    DEFF Research Database (Denmark)

    Gislason, Sigurdur R.; Broecker, W.S.; Gunnlaugsson, E.;

    2014-01-01

    The long-term security of geologic carbon storage is critical to its success and public acceptance. Much of the security risk associated with geological carbon storage stems from its buoyancy. Gaseous and supercritical CO2 are less dense than formation waters, providing a driving force...... for it to escape back to the surface. This buoyancy can be eliminated by the dissolution of CO2 into water prior to, or during its injection into the subsurface. The dissolution makes it possible to inject into fractured rocks and further enhance mineral storage of CO2 especially if injected into silicate rocks...... rich in divalent metal cations such as basalts and ultra-mafic rocks. We have demonstrated the dissolution of CO2 into water during its injection into basalt leading to its geologic solubility storage in less than five minutes and potential geologic mineral storage within few years after injection [1...

  10. Flood basalt volcanism during the past 250 million years

    Science.gov (United States)

    Rampino, Michael R.; Stothers, Richard B.

    1988-01-01

    A chronology of the initiation dates of major continental flood basalt volcanism is established from published potassium-argon (K-Ar) and argon-argon (Ar-Ar) ages of basaltic rocks and related basic intrusions. The dating is therefore independent of the biostratigraphic and paleomagnetic time scales. Estimated errors of the initiation dates of the volcanic episodes determined from the distributions of the radiometric ages are, approximately, + or - 4 percent. There were 11 distinct episodes during the past 250 million years. Sometimes appearing in pairs, the episodes have occurred quasi-periodically with a mean cycle time of 32 + or - 1 (estimated error of the mean) million years. The initiation dates of the episodes are close to the estimated dates of mass extinctions of marine organisms. Showers of impacting comets may be the cause.

  11. Transient β-hairpin formation in α-synuclein monomer revealed by coarse-grained molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Hang; Ma, Wen [Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Han, Wei [Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Schulten, Klaus, E-mail: kschulte@ks.uiuc.edu [Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2015-12-28

    Parkinson’s disease, originating from the intrinsically disordered peptide α-synuclein, is a common neurodegenerative disorder that affects more than 5% of the population above age 85. It remains unclear how α-synuclein monomers undergo conformational changes leading to aggregation and formation of fibrils characteristic for the disease. In the present study, we perform molecular dynamics simulations (over 180 μs in aggregated time) using a hybrid-resolution model, Proteins with Atomic details in Coarse-grained Environment (PACE), to characterize in atomic detail structural ensembles of wild type and mutant monomeric α-synuclein in aqueous solution. The simulations reproduce structural properties of α-synuclein characterized in experiments, such as secondary structure content, long-range contacts, chemical shifts, and {sup 3}J(H{sub N}H{sub C{sub α}})-coupling constants. Most notably, the simulations reveal that a short fragment encompassing region 38-53, adjacent to the non-amyloid-β component region, exhibits a high probability of forming a β-hairpin; this fragment, when isolated from the remainder of α-synuclein, fluctuates frequently into its β-hairpin conformation. Two disease-prone mutations, namely, A30P and A53T, significantly accelerate the formation of a β-hairpin in the stated fragment. We conclude that the formation of a β-hairpin in region 38-53 is a key event during α-synuclein aggregation. We predict further that the G47V mutation impedes the formation of a turn in the β-hairpin and slows down β-hairpin formation, thereby retarding α-synuclein aggregation.

  12. A new basaltic glass microanalytical reference material for multiple techniques

    Science.gov (United States)

    Wilson, Steve; Koenig, Alan; Lowers, Heather

    2012-01-01

    The U.S. Geological Survey (USGS) has been producing reference materials since the 1950s. Over 50 materials have been developed to cover bulk rock, sediment, and soils for the geological community. These materials are used globally in geochemistry, environmental, and analytical laboratories that perform bulk chemistry and/or microanalysis for instrument calibration and quality assurance testing. To answer the growing demand for higher spatial resolution and sensitivity, there is a need to create a new generation of microanalytical reference materials suitable for a variety of techniques, such as scanning electron microscopy/X-ray spectrometry (SEM/EDS), electron probe microanalysis (EPMA), laser ablation inductively coupled mass spectrometry (LA-ICP-MS), and secondary ion mass spectrometry (SIMS). As such, the microanalytical reference material (MRM) needs to be stable under the beam, be homogeneous at scales of better than 10–25 micrometers for the major to ultra-trace element level, and contain all of the analytes (elements or isotopes) of interest. Previous development of basaltic glasses intended for LA-ICP-MS has resulted in a synthetic basaltic matrix series of glasses (USGS GS-series) and a natural basalt series of glasses (BCR-1G, BHVO-2G, and NKT-1G). These materials have been useful for the LA-ICP-MS community but were not originally intended for use by the electron or ion beam community. A material developed from start to finish with intended use in multiple microanalytical instruments would be useful for inter-laboratory and inter-instrument platform comparisons. This article summarizes the experiments undertaken to produce a basalt glass reference material suitable for distribution as a multiple-technique round robin material. The goal of the analytical work presented here is to demonstrate that the elemental homogeneity of the new glass is acceptable for its use as a reference material. Because the round robin exercise is still underway, only

  13. Investigation on mechanical properties of basalt composite fabrics (experiment study)

    OpenAIRE

    Talebi Mazraehshahi H.; Zamani H.

    2010-01-01

    To fully appreciate the role and application of composite materials to structures, correct understanding of mechanical behaviors required for selection of optimum material. Fabric reinforced composites are composed of a matrix that is reinforced with pliable fabric, glass fabric is most popular reinforcement for different application specially in aircraft structure, although other fabric material are also used. At this study new fabric material called basalt with epoxy resin introduced ...

  14. Initial effects of vegetation on Hawaiian basalt weathering rates

    Energy Technology Data Exchange (ETDEWEB)

    Cochran, M.F.; Berner, R.A. (Yale Univ., New Haven, CT (United States))

    1992-01-01

    Weathering of Ca and Mg silicates on land and ensuing precipitation and burial of Ca and Mg carbonates in marine sediments is the principal sink for carbon dioxide from the atmosphere/ocean system on geologic time scales. Model calculations of ancient atmospheric CO[sub 2] partial pressure depend strongly on the authors assumptions about the enhancement of silicate weathering rates first by primitive terrestrial biota, then by the appearance and evolution of the vascular plants. Aa and pahoehoe basalts were collected from Mauna Loa and Kilauea volcanoes on the island of Hawaii. Flows ranged in age (one year to several thousand years) and in ambient climate. Where possible, each flow was sampled beneath a suite of current plant covers: none, lichens, and higher plants. Rocks were embedded in epoxy to preserve the plant-rock interface, then sectioned and subjected to electron probe microanalysis. During initial weathering, vascular plants appeared to promote congruent dissolution of minerals (particularly olivine and Ca-rich plagioclase) and glass near the surfaces of underlying basalts. In the neighborhood of roots, primary cracks widened with time into networks of open channels. This effect was observed prior to the formation of measurable leached zones in exterior grains and prior to the appearance of secondary minerals. As a result, initial mass loss from young, plant-covered basalts appeared to be up to one or more orders of magnitude greater than from bare-rock controls. Despite earlier reports of substantial enhancement of Hawaiian basalt weathering rates by the lichen Stereocaulon vulcani, weathering observed beneath this lichen was comparable to that of unvegetated rocks.

  15. Putative cryptoendolithic life in Devonian pillow basalt, Rheinisches Schiefergebirge, Germany.

    Science.gov (United States)

    Peckmann, J; Bach, W; Behrens, K; Reitner, J

    2008-03-01

    Middle Devonian (Givetian) pillow basalt and inter-pillow breccia from the Rheinisches Schiefergebirge in Germany were found to contain putative biogenic filaments that indicate that life once proliferated within these volcanic rocks. Mineralized filaments are found in carbonate amygdules (vesicles filled by carbonate cement) in the volcanic rock, where they started to form on the internal surface of the once water-filled vesicles. Biogenicity of the filaments is indicated by (1) their size and shape resembling modern microorganisms including a constant diameter along the length of curved filaments, (2) their independence of crystal faces or cleavage planes, (3) branching patterns reminiscent of modern microorganisms, and (4) their spatial clustering and preferential occurrence close to the margin of pillows and in the inter-pillow breccias. A time lag between the deposition of pillow basalt and the activity of endoliths is revealed by the sequence of carbonate cements filling the amygdules. The putative filamentous microorganisms thrived after the formation of early fibrous rim cement, but before later equant calcite spar filled most of the remaining porosity. Microbial clay authigenesis analogous to the encrustation of prokaryotes in modern iron-rich environments led to the preservation of filaments. The filaments predominantly consist of the clay minerals chamosite and illite. Having dwelled in water-filled vesicles, the Devonian basalt-hosted filaments apparently represent cryptoendoliths. This finding suggests that a previously unrecognized niche for life exists within volcanic rock.

  16. Basalt Pb isotope analysis and the prehistoric settlement of Polynesia.

    Science.gov (United States)

    Weisler, M I; Woodhead, J D

    1995-03-14

    The prehistoric settlement of the Pacific Ocean has intrigued scholars and stimulated anthropological debate for the past two centuries. Colonized over a few millennia during the mid to late Holocene, the islands of the Pacific--displaying a wide diversity of geological and biotic variability--provided the stage for endless "natural experiments" in human adaptation. Crucial to understanding the evolution and transformation of island societies is documenting the relative degree of interisland contacts after island colonization. In the western Pacific, ideal materials for archaeologically documenting interisland contact--obsidian, pottery, and shell ornaments--are absent or of limited geographic distribution in Polynesia. Consequently, archaeologists have relied increasingly on fine-grained basalt artifacts as a means for documenting colonization routes and subsequent interisland contacts. Routinely used x-ray fluorescence characterization of oceanic island basalt has some problems for discriminating source rocks and artifacts in provenance studies. The variation in trace and major element abundances is largely controlled by near-surface magma-chamber processes and is broadly similar between most oceanic islands. We demonstrate that Pb isotope analysis accurately discriminates rock source and is an excellent technique for charting the scale, frequency, and temporal span of imported fine-grained basalt artifacts found throughout Polynesia. The technique adds another tool for addressing evolutionary models of interaction, isolation, and cultural divergence in the eastern Pacific.

  17. Carbon dioxide sequestration in deep-sea basalt.

    Science.gov (United States)

    Goldberg, David S; Takahashi, Taro; Slagle, Angela L

    2008-07-22

    Developing a method for secure sequestration of anthropogenic carbon dioxide in geological formations is one of our most pressing global scientific problems. Injection into deep-sea basalt formations provides unique and significant advantages over other potential geological storage options, including (i) vast reservoir capacities sufficient to accommodate centuries-long U.S. production of fossil fuel CO2 at locations within pipeline distances to populated areas and CO2 sources along the U.S. west coast; (ii) sufficiently closed water-rock circulation pathways for the chemical reaction of CO2 with basalt to produce stable and nontoxic (Ca(2+), Mg(2+), Fe(2+))CO(3) infilling minerals, and (iii) significant risk reduction for post-injection leakage by geological, gravitational, and hydrate-trapping mechanisms. CO2 sequestration in established sediment-covered basalt aquifers on the Juan de Fuca plate offer promising locations to securely accommodate more than a century of future U.S. emissions, warranting energized scientific research, technological assessment, and economic evaluation to establish a viable pilot injection program in the future.

  18. Interim reclamation report, Basalt Waste Isolation project: Boreholes, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, C.A.; Rickard, W.H. Jr.; Hefty, M.G.

    1990-03-01

    In 1968, a program was started to assess the feasibility of storing Hanford Site defense waste in deep caverns constructed in basalt. This program was expanded in 1976 to include investigations of the Hanford Site as a potential location for a mined commercial nuclear waste repository. An extensive site characterization program was begun to determine the feasibility of using the basalts beneath the Hanford Site for the repository. Site research focused primarily on determining the direction and speed of groundwater movement, the uniformity of basalt layers, and tectonic stability. Some 98 boreholes were sited, drilled, deepened, or modified by BWIP between 1977 and 1988 to test the geologic properties of the Site. On December 22, 1987, President Reagan signed into law the Nuclear Waste Policy Amendments Act of 1987, which effectively stopped all repository-related activities except reclamation of disturbed lands at the Hanford Site. This report describes the development of the reclamation program for the BWIP boreholes, its implementation, and preliminary estimates of its success. The goal of the reclamation program is to return sites disturbed by the repository program as nearly as practicable to their original conditions using native plant species. 48 refs., 28 figs., 14 tabs.

  19. Interim reclamation report, Basalt Waste Isolation project: Boreholes, 1989

    International Nuclear Information System (INIS)

    In 1968, a program was started to assess the feasibility of storing Hanford Site defense waste in deep caverns constructed in basalt. This program was expanded in 1976 to include investigations of the Hanford Site as a potential location for a mined commercial nuclear waste repository. An extensive site characterization program was begun to determine the feasibility of using the basalts beneath the Hanford Site for the repository. Site research focused primarily on determining the direction and speed of groundwater movement, the uniformity of basalt layers, and tectonic stability. Some 98 boreholes were sited, drilled, deepened, or modified by BWIP between 1977 and 1988 to test the geologic properties of the Site. On December 22, 1987, President Reagan signed into law the Nuclear Waste Policy Amendments Act of 1987, which effectively stopped all repository-related activities except reclamation of disturbed lands at the Hanford Site. This report describes the development of the reclamation program for the BWIP boreholes, its implementation, and preliminary estimates of its success. The goal of the reclamation program is to return sites disturbed by the repository program as nearly as practicable to their original conditions using native plant species. 48 refs., 28 figs., 14 tabs

  20. Basalt Waste Isolation Project. Annual report, fiscal year 1980

    International Nuclear Information System (INIS)

    During this fiscal year the information available in the fields of geology and hydrology of the Columbia Plateau was consolidated and two reports were issued summarizing this information. In addition, the information on engineered barriers was consolidated and a report summarizing the research to date on waste package development and design of borehole seals was prepared. The waste package studies, when combined with the hydrologic integration, revealed that even under extreme disruptive conditions, a repository in basalt with appropriately designed waste packages can serve as an excellent barrier for containment of radionuclides for the long periods of time required for waste isolation. On July 1, 1980, the first two heater tests at the Near-Surface Test Facility were started and have been successfully operated to this date. The papers on the Near-Surface Test Facility section of this report present the results of the equipment installed and the preliminary results of the testing. In October 1979, the US Department of Energy selected the joint venture of Kaiser Engineers/Parsons Brinckerhoff Quade and Douglas, Inc., to be the architect-engineer to produce a conceptual design of a repository in basalt. During the year, this design has progressed and concept selection has now been completed. This annual report presents a summary of the highlights of the work completed during fiscal year 1980. It is intended to supplement and summarize the nearly 200 papers and reports that have been distributed to date as a part of the Basalt Waste Isolation Project studies

  1. Basalt Waste Isolation Project. Annual report, fiscal year 1980

    Energy Technology Data Exchange (ETDEWEB)

    1980-11-01

    During this fiscal year the information available in the fields of geology and hydrology of the Columbia Plateau was consolidated and two reports were issued summarizing this information. In addition, the information on engineered barriers was consolidated and a report summarizing the research to date on waste package development and design of borehole seals was prepared. The waste package studies, when combined with the hydrologic integration, revealed that even under extreme disruptive conditions, a repository in basalt with appropriately designed waste packages can serve as an excellent barrier for containment of radionuclides for the long periods of time required for waste isolation. On July 1, 1980, the first two heater tests at the Near-Surface Test Facility were started and have been successfully operated to this date. The papers on the Near-Surface Test Facility section of this report present the results of the equipment installed and the preliminary results of the testing. In October 1979, the US Department of Energy selected the joint venture of Kaiser Engineers/Parsons Brinckerhoff Quade and Douglas, Inc., to be the architect-engineer to produce a conceptual design of a repository in basalt. During the year, this design has progressed and concept selection has now been completed. This annual report presents a summary of the highlights of the work completed during fiscal year 1980. It is intended to supplement and summarize the nearly 200 papers and reports that have been distributed to date as a part of the Basalt Waste Isolation Project studies.

  2. Radiolytic Hydrogen Production in the South Pacific Subseafloor Basaltic Aquifer

    Science.gov (United States)

    Dzaugis, M. E.; Spivack, A. J.; Dunlea, A. G.; Murray, R. W.; D'Hondt, S.

    2015-12-01

    Hydrogen (H2) is produced in geological settings by dissociation of water due to radiation from natural radioactive decay of uranium (238U, 235U), thorium (232Th) and potassium (40K). To quantify the potential significance of radiolytic H2 as an electron donor for microbes within the South Pacific subseafloor basaltic aquifer, we calculate radiolytic H2 production rates in basement fractures utilizing measured radionuclide concentrations in 42 basalt samples from IODP Expedition 329. The samples are from three sites with very different basement ages and a wide range of alteration types. Major and trace element concentrations vary by up to an order of magnitude from sample to sample. Comparison of our samples to each other and to previous studies of fresh East Pacific Rise basalt suggests that between-sample variation in radionuclide concentrations is primarily due to differences in initial (pre-alteration) concentrations (which can vary between eruptive events), rather than to alteration type or extent. Local maxima in radionuclide (U, Th, and K) concentrations produce 'hotspots' of radiolytic H2 production; calculated radiolytic rates differ by up to a factor of 80 from sample to sample. Fracture width also greatly influences H2 production. Due to the low penetration distance of alpha radiation, microfractures are 'hotpots' for radiolytic H2 production. For example, radiolytic H2 production rates normalized to water volume are 170 times higher in 1μm-wide fractures than in 10cm-wide fractures.

  3. The consanguinity of the oldest Apollo 11 mare basalts

    Science.gov (United States)

    Gamble, R. P.; Coish, R. A.; Taylor, L. A.

    1978-01-01

    The textural, mineralogical, and chemical relationships between three of the oldest dates lunar mare basalt samples returned by Apollo 11 (10003, 10029 and 10062) were investigated. Very strong resemblances were noted between the modal minerologies of 10003 and 10029. Significantly more modal olivine and cristobalite was observed in 10062 than in the other basalt samples. A detailed examination of mineral-chemical relationships among the samples revealed similarities between 10003 and 10062 and differences between these two rocks and 10029, the most significant of which is the presence of akaganeite in 10029, implying that lawrencite was present in the pristine sample of 10029 but not in 10003 and 10062. Results of a Wright-Doherty mixing program used to test various fractional crystallization schemes show that 10062 can be derived from a liquid with the composition of either 10003 or 10029 by removing 2-5% ilmenite and 5% olivine. By removing about 6% plagioclase, 10003 can be derived from a liquid with the bulk composition of 10062. It is concluded that 10003 and 10029 may have come from different basaltic flows, whereas it is possible that 10003 and 10062 were derived from the same parental magma by near-surface fractionation of olivine plus ilmenite or of plagioclase plus or minus olivine.

  4. Organic matter dynamics in coarse sandy calcareous soils

    OpenAIRE

    Pronk, A.A.; Reuler, van, H.

    2011-01-01

    The decomposition of organic matter in coarse sandy calcareous soils (beach sand) is thought to be much higher than in acid fine sandy soils but relatively little research is performed on these soils. Laboratory incubation experiments in which the release of soil carbon (C) is determined may overestimate the release of the soil organic C, as part of the measured C may have been released from the soil carbonates. In addition, it is not clear if the contribution of organic applications to the s...

  5. A system for coarse-grained location-based synchronisation

    CERN Document Server

    Coelho, André; Silva, Mário; José, Rui

    2010-01-01

    This paper describes a system for supporting coarse-grained location-based synchronisation. This type of synchronisation may occur when people need only some awareness about the location of others within the specific context of an on-going activity. We have identified a number of reference scenarios for this type of synchronisation and we have implemented and deployed a prototype to evaluate the type of support provided. The results of the evaluation suggest a good acceptance of the overall concept, indicating that this might be a valuable approach for many of the indicated scenarios, possibly replacing or complementing existing synchronisation practices.

  6. Coarse fraction of soils from building rubble (WWII)

    Science.gov (United States)

    Mekiffer, Beate; Wessolek, Gerd; Scheytt, Traugott; Bussert, Robert; Nehls, Thomas

    2010-05-01

    Soils, resulting from building rubble of WWII are wide spread in whole Europe. The parent material for pedogenesis originates from different kinds of buildings, which where destroyed of different ways. Also the kind of sorting and disposing was varying for this material. So the most important feature of soils, resulting from building rubble of WWII, is their heterogeneity. We investigated samples of soils developed from building rubble to answer the following questions: ­ What are the amounts of coarse fraction and what are their main components? ­ What are the chemical properties and what is the crystalline mineral composition of technogenic components? ­ What is the release of ions from coarse technogenic components? We sieved and hand sorted the materials, used the X-ray diffractometry and X-ray fluorescence spectroscopy and measured the ions released in 1:2-extract. In most cases, the soils have a high amount of coarse fraction (> 2mm) (median 25% w/w, N=52). Dominating components in the coarse fraction are in the order of decreasing abundance: bricks, mortar (incl. plaster and stucco), slag, ashes and unburned coals. The analyzed components show alkalescent to alkaline pH-values. 75% of the samples show low electrical conductivities of up to 141 µS/cm. Bricks mainly consist of Si oxides, followed by oxides of Al, Ca, Fe, Mg and K. X-Ray-diffractometry of bricks showed, that most common minerals are clay minerals (Kaolinit, Illit, Montmorillonit and Chlorit), Quarz, and Carbonates (Calcite and Dolomite, Siderite). Bricks contain Fe-Oxides (Hematite, Goethite), Sulphates and Sulfides (Gypsum, Pyrite, Markasite) in lower amounts. 5-20 % of the minerals are x-ray-amorphous. Mortar is characterized by a high amount of silicates (nearby 80%). The samples showed a lower percentage of Al- and Ca-compounds than bricks. Chemical composition of ashes and slag varies in wide ranges, depending on their genesis. We found mainly ashes from stove heating. They contained

  7. Symmetry-based coarse-graining of evolved dynamical networks

    CERN Document Server

    Karalus, Steffen

    2015-01-01

    Networks with prescribed subdiffusive dynamical behavior can be generated by evolutionary optimization applied to the spectrum of the graph Laplacian. When the evolution algorithm is constrained to preserve degree-regularity, the evolved networks display an abundance of certain motifs arranged into loops and long linear segments. We use algebraic graph theory to construct the quotient networks induced by the symmetries underlying the motifs. The resulting coarse-grained networks display improved pectral properties and provide an intuitive view of how the anomalous diffusive properties are realized in the evolved structures.

  8. MICROTHREAD BASED (MTB) COARSE GRAINED FAULT TOLERANCE SUPERSCALAR PROCESSOR ARCHITECTURE

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Fault tolerance in microprocessor systems has become a popular topic of architecture research.Much work has been done at different levels to accomplish reliability against soft errors, and some fault tolerance architectures have been proposed. But little attention is paid to the thread level superscalar fault tolerance.This letter introduces microthread concept into superscalar processor fault tolerance domain, and puts forward a novel fault tolerance architecture, namely, MicroThread Based (MTB) coarse grained transient fault tolerance superscalar processor architecture, then discusses some detailed implementations.

  9. Coarsely Invariant Hilbert Spaces over Infinite Connected Graphs

    Institute of Scientific and Technical Information of China (English)

    WANG Qin

    2002-01-01

    We study in this paper a Hilbert space HV associated with the coarse geometry of an infinite connected graph X(V, E) with vertex set V and edge set E. We show that X(V,E) is uniformly expanding if and only ifl2(V)can be continuously included in HV as a closed subspace,and that the inner product structure of HV is topologically invariant under uniform coarsening of the graph. We also discuss the functorial properties of these Hilbert spaces.

  10. Flow behavior of coarse-grained slurries in pipes

    OpenAIRE

    Vlasák, P.; Chára, Z.; Kysela, B. (Bohuš); Sobota , J.

    2011-01-01

    The paper describes the experimental investigation of model coarse-grained slurry on a recirculation pipe loop with smooth stainless steel pipes. Graded pebble gravel and glass balls were used as a model for poly-metallic nodules, and very fine glass beads as a model for fine-grained sand. The investigation was focused on evaluating the effect of slurry velocity and particle concentration on pressure drops and the slurry flow behavior in the turbulent regime. Also the effect of fine-grained p...

  11. Realistic coarse-grained cosmic structure from Szekeres models

    CERN Document Server

    Sussman, Roberto A

    2015-01-01

    A systematic self-consistent procedure is provided to describe by means of the Szekeres dust models the evolution of multiple self-gravitating cold dark matter structures (over-densities and density voids), whose spatial location can be prescribed beforehand for all times by suitable initial conditions that define the free parameters of the models. Following this procedure makes it possible to obtain a fully relativistic non-perturbative coarse grained description of actually existing cosmic structure at various scales. We discuss possible astrophysical and cosmological applications.

  12. Studies on eco-friendly concrete incorporating industrial waste as aggregates

    Directory of Open Access Journals (Sweden)

    Nitendra Palankar

    2015-12-01

    Full Text Available The present day research is focussed on development of alternative binder materials to Ordinary Portland Cement (OPC due to huge emissions of green house gases associated with production of OPC. GGBFS-FA based geopolymer binders are an innovative alternative to OPC which can obtain high strengths apart from being eco-friendly; since its production does not involve high energy and also contributes to sustainability by using the industrial waste materials. Steel slag, an industrial by-product obtained from manufacture of steel can be identified as an alternative to natural aggregates for concrete production, since there is a possibility of acute shortage of natural aggregates in future. The present study is conducted to evaluate the performance of weathered steel slag coarse aggregates in GGBFS-FA based geopolymer concrete. GGBFS-FA geopolymer concrete with steel slag coarse aggregates are prepared by replacing natural granite aggregates at different replacement levels i.e. 0%, 25%, 50%, 75% and 100% (by volume and various fresh and mechanical properties are studied. The flexural fatigue behaviour of GGBFS-FA geopolymer concrete with steel slag is also studied in detail. Efforts are also made to model the probabilistic distribution of fatigue data of GGBFS-FA geopolymer concrete at different stress levels using two parameters Weibull distribution. The results indicated that incorporation of steel slag in GGBFS-FA geopolymer concrete resulted in slight reduction in mechanical strength. The water absorption and volume of permeable voids displayed higher values with inclusion of steel slag. Reduction in number of cycles for fatigue failure was observed in geopolymer concrete mixes containing steel slag as compared to granite aggregates. Overall, the performance of steel slag was found to be satisfactory for structural and pavement application and steel slag can be recognised as new construction material.

  13. Dependability in Aggregation by Averaging

    CERN Document Server

    Jesus, Paulo; Almeida, Paulo Sérgio

    2010-01-01

    Aggregation is an important building block of modern distributed applications, allowing the determination of meaningful properties (e.g. network size, total storage capacity, average load, majorities, etc.) that are used to direct the execution of the system. However, the majority of the existing aggregation algorithms exhibit relevant dependability issues, when prospecting their use in real application environments. In this paper, we reveal some dependability issues of aggregation algorithms based on iterative averaging techniques, giving some directions to solve them. This class of algorithms is considered robust (when compared to common tree-based approaches), being independent from the used routing topology and providing an aggregation result at all nodes. However, their robustness is strongly challenged and their correctness often compromised, when changing the assumptions of their working environment to more realistic ones. The correctness of this class of algorithms relies on the maintenance of a funda...

  14. Isolation and Aggregation in Economics

    OpenAIRE

    Schlicht, Ekkehart

    1985-01-01

    In explaining economic phenomena, economic analysis concentrates on selected influences and fixes the host of other factors under a ceteris paribus clause. This view, which goes back to Alfred Marshall (1842-1924), is developed in the first part of the book. Aggregation is viewed as a particular application of ceteris paribus analysis - isolation from "structural effects". This leads to an approach, called "closed aggregation", which was introduced by Kenneth May and is also implicit in Keyne...

  15. Mucin aggregation from a rod-like meso-scale model

    Science.gov (United States)

    Moreno, Nicolas; Perilla, Jairo E.; Colina, Coray M.; Lísal, Martin

    2015-05-01

    Dissipative particle dynamics, a meso-scale particle-based model, was used to study the aggregation of mucins in aqueous solutions. Concentration, strength of the mucin-water interactions, as well as the effects of size, shape, and composition of the model molecules were studied. Model proteins were represented as rod-like objects formed by coarse-grained beads. In the first model, only one type of beads formed the mucin. It was found that all the surfaces were available to form aggregates and the conformation of the aggregates was a function of the strength of the mucin-water interaction. With this model, the number of aggregates was unaffected by the initial position of the mucins in the simulation box, except for the lowest mucin concentration. In a more refined mucin model, two kinds of beads were used in the molecule in order to represent the existence of cysteine-like terminal groups in the actual molecule. With this new scheme, aggregation took place by the interaction of the terminal groups between model molecules. The kinetic analysis of the evolution of the number of aggregates with time was also studied for both mucin models.

  16. Carbonation Coefficients from Concrete Made with High-Absorption Limestone Aggregate

    Directory of Open Access Journals (Sweden)

    Eric I. Moreno

    2013-01-01

    Full Text Available Normal aggregates employed in concrete have absorption levels in the range of 0.2% to 4% for coarse aggregate and 0.2 to 2% for fine aggregate. However, some aggregates have absorption levels above these values. As the porosity of concrete is related to the porosity of both the cement paste and the aggregate and the carbonation rate is a function, among other things, of the porosity of the material, there is concern about the effect of this high porosity material in achieving good quality concrete from the durability point of view. Thus, the objective of this investigation was to study the carbonation rates of concrete specimens made with high-absorption limestone aggregate. Four different water/cement ratios were used, and cylindrical concrete specimens were exposed to accelerated carbonation. High porosity values were obtained for concrete specimens beyond the expected limits for durable concrete. However, carbonation coefficients related to normal quality concrete were obtained for the lowest water/cement ratio employed suggesting that durable concrete may be obtained with this material despite the high porosity.

  17. Physico-mechanical properties of solid cement bricks containing recycled aggregates

    Directory of Open Access Journals (Sweden)

    Dina M. Sadek

    2012-07-01

    Full Text Available Recycling and reuse of solid wastes as alternative building materials present interesting possibilities for economy on waste disposal sites and conservation of natural resources. This paper investigates the physical and mechanical properties of solid cement bricks manufactured with crushed clay bricks as recycled aggregates. Four series of mixtures with cement content 100, 150, 200 and 300 kg/m3 were prepared. In each series, either natural fine aggregate, coarse aggregate or both were replaced with crushed brick aggregates (CBA at 0%, 50% and 100% by volume. Compressive strength, unit weight and water absorption were determined and compared with the relevant national and international standards for load bearing and non-load bearing units, respectively. The experimental results showed that as the replacement level of natural aggregates increased, the unit weight and compressive strength of solid cement bricks decreased and the water absorption increased regardless of cement content. Furthermore, it is possible to manufacture different grades of solid cement bricks with CBA to be used as load bearing and non-load bearing units depending on the size of the crushed bricks and the replacement percentage of natural aggregates.

  18. Influence of recycled aggregate quality and proportioning criteria on recycled concrete properties.

    Science.gov (United States)

    López-Gayarre, F; Serna, P; Domingo-Cabo, A; Serrano-López, M A; López-Colina, C

    2009-12-01

    This paper presents the results of experimental research using concrete produced by substituting part of the natural coarse aggregates with recycled aggregates from concrete demolition. The influence of the quality of the recycled aggregate (amount of declassified and source of aggregate), the percentage of replacement on the targeted quality of the concrete to be produced (strength and workability) has been evaluated. The granular structure of concrete and replacement criteria were analyzed in this study, factors which have not been analyzed in other studies. The following properties of recycled concretes were analyzed: density, absorption, compressive strength, elastic modulus, amount of occluded air, penetration of water under pressure and splitting tensile strength. A simplified test program was designed to control the costs of the testing while still producing sufficient data to develop reliable conclusions in order to make the number of tests viable whilst guaranteeing the reliability of the conclusions. Several factors were analyzed including the type of aggregate, the percentage of replacement, the type of sieve curve, the declassified content, the strength of concrete and workability of concrete and the replacement criteria. The type of aggregate and the percentage of replacement were the only factors that showed a clear influence on most of the properties. Compressive strength is clearly affected by the quality of recycled aggregates. If the water-cement ratio is kept constant and the loss of workability due to the effect of using recycled aggregate is compensated for with additives, the percentage of replacement of the recycled aggregate will not affect the compressive strength. The elastic modulus is affected by the percentage of replacement. If the percentage of replacement does not exceed 50%, the elastic modulus will only change slightly. PMID:19709870

  19. Simulating Fiber Ordering and Aggregation In Shear Flow Using Dissipative Particle Dynamics

    Science.gov (United States)

    Stimatze, Justin T.

    We have developed a mesoscale simulation of fiber aggregation in shear flow using LAMMPS and its implementation of dissipative particle dynamics. Understanding fiber aggregation in shear flow and flow-induced microstructural fiber networks is critical to our interest in high-performance composite materials. Dissipative particle dynamics enables the consideration of hydrodynamic interactions between fibers through the coarse-grained simulation of the matrix fluid. Correctly simulating hydrodynamic interactions and accounting for fluid forces on the microstructure is required to correctly model the shear-induced aggregation process. We are able to determine stresses, viscosity, and fiber forces while simulating the evolution of a model fiber system undergoing shear flow. Fiber-fiber contact interactions are approximated by combinations of common pairwise forces, allowing the exploration of interaction-influenced fiber behaviors such as aggregation and bundling. We are then able to quantify aggregate structure and effective volume fraction for a range of relevant system and fiber-fiber interaction parameters. Our simulations have demonstrated several aggregate types dependent on system parameters such as shear rate, short-range attractive forces, and a resistance to relative rotation while in contact. A resistance to relative rotation at fiber-fiber contact points has been found to strongly contribute to an increased angle between neighboring aggregated fibers and therefore an increase in average aggregate volume fraction. This increase in aggregate volume fraction is strongly correlated with a significant enhancement of system viscosity, leading us to hypothesize that controlling the resistance to relative rotation during manufacturing processes is important when optimizing for desired composite material characteristics.

  20. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete

    Directory of Open Access Journals (Sweden)

    Antonio López-Uceda

    2016-02-01

    Full Text Available This research aims to produce non-structural concrete with mixed recycled aggregates (MRA in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%, using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors’ knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.