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Sample records for concrete filled double

  1. Axial Compression Properties Nonlinear Analysis on Square Double Skin Steel Stub Short Columns Filled with Recycled Concrete

    Directory of Open Access Journals (Sweden)

    Song Bing

    2016-01-01

    Full Text Available Taking the mixing amount of diatomite calcined and vitrified micro bubbles(VMB as the main changing parameters, experiment studies the properties of the vitrified micro bubbles recycled concrete blocks; then this paper adopts the finite element software ANSYS to analyze the square double skin steel stub short columns filled with recycled concrete under axial compression. According to the vertical stress distribution, strain and bearing capacity of the steel tube and core concrete, we make a contrastive axial compression properties analysis on the different hollow ratio χ(0,0.35and the VMB content(0%,100%,130% of square double skin steel stub short columns filled with recycled concrete. The result shows that: Compressive strength of VMB recycled concrete increases with the increase of diatomite calcined content, when mixing amount of diatomite calcined is 3%,the compressive strength of 130% VMB content test specimen can reach 32.45 MPa;Because of the inner circular steel tube is setted which strengthening component buckling capacity and improving the ductility of the component, stress distribution of hollow components is more balance than solid components, and their axial displacements decrease by 5.6% compared with the solid components when they reach ultimate bearing capacity; When the hollow ratio is same, ultimate bearing capacity of 130% VMB content test specimen compared with the content is 0% only reduces by about 3.5%; When the VMB content is same, ultimate bearing capacity of hollow components compared with solid components increases by about 2.5%, which reducing weight as well as improving the anti-seismic performance.

  2. Form Filling with Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2002-01-01

    This paper describes a newly started Ph.D. project with the aim of simulating the form filling ability of Self-Compacting Concrete (SCC) taking into account the form geometry, reinforcement configuration, casting technique, and the rheological properties of the concrete. Comparative studies...

  3. Application of concrete filled steel bearing wall to inner concrete structure fro PWR nuclear power plant

    International Nuclear Information System (INIS)

    Sekimoto, Hisashi; Tanaka, Mamoru; Inoue, Kunio; Fukihara, Masaaki; Akiyama, Hiroshi.

    1992-01-01

    'Concrete filled steel bearing wall', applied to the inner concrete structure for PWR nuclear power plant, was developed for rationalization of construction procedure at site. It was concluded through preliminary studies that this new type of wall, where concrete is placed between steel plates, is best suited for the strength members of the above structure, due to the high strength and ductility of surface steel plates and the confinement effect of filled concrete. To verify the behavior from the elastic range to the inelastic range, the ultimate strength and the failure mechanism, and to clarify experimentally the structural integrity of the inner concrete structure, which was composed of a concrete filled steel bearing wall, against seismic lateral loads, horizontal loading tests using a 1/10th scale model of the inner concrete structure for PWR nuclear power plant were conducted. As a result of the tests, the inner concrete structure composed of a concrete filled steel bearing wall appeared to have a larger load carrying capacity and a higher ductility as compared with that composed of a reinforced concrete wall. (author)

  4. Flexural Behavior of GFRP Tubes Filled with Magnetically Driven Concrete.

    Science.gov (United States)

    Xie, Fang; Chen, Ju; Dong, Xinlong; Feng, Bing

    2018-01-08

    Experimental investigation of GFRP (glass fiber reinforced polymer) tubes that were filled with magnetically driven concrete was carried out to study the flexural behavior of specimens under bending. Specimens having different cross section and lengths were tested. The test specimens were fabricated by filling magnetically driven concrete into the GFRP tubes and the concrete was vibrated using magnetic force. Specimens vibrated using vibrating tube were also tested for comparison. In addition, specimens having steel reinforcing bars and GFRP bars were both tested to study the effect of reinforcing bars on the magnetically driven concrete. The load-displacement curves, load-strain curves, failure mode, and ultimate strengths of test specimens were obtained. Design methods for the flexural stiffness of test specimens were also discussed in this study.

  5. Form Filling with Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2007-01-01

    to the prospects of improving the structural quality, working environment, productivity, and architectural appearance. However, especially in vertical applications there is a great unused potential. Controlling the casting process is important in many different industries such as the metal, plastic, and food...... the framework of Computational Fluid Dynamics (CFD). CFD is applied to simulate the homogeneous form filling characteristics, i.e. the form filling ability and flow patterns, taking into account the rheological properties and casting technique. It is assumed that the rheological properties of SCC follow...... dimensions. For the heterogeneous flow phenomena, this project focusses on the assessment of blocking, which is of special interest in relation to high quality and complicated structures with a dense reinforcement configuration. A phenomenological micro-mechanical model has been developed, which introduces...

  6. Concrete-Filled Steel Tube Arch Bridges in China

    Directory of Open Access Journals (Sweden)

    Jielian Zheng

    2018-02-01

    Full Text Available In the past 20 years, great progress has been achieved in China in the construction of concrete-filled steel tube (CFST arch bridges and concrete arch bridges with a CFST skeleton. The span of these bridges has been increasing rapidly, which is rare in the history of bridge development. The large-scale construction of expressways and high-speed railways demands the development of long-span arch bridges, and advances in design and construction techniques have made it possible to construct such bridges. In the present study, the current status, development, and major innovative technologies of CFST arch bridges and concrete arch bridges with a CFST skeleton in China are elaborated. This paper covers the key construction technologies of CFST arch bridges, such as the design, manufacture, and installation of steel tube arch trusses, the preparation and pouring of in-tube concrete, and the construction of the world’s longest CFST arch bridge—the First Hejiang Yangtze River Bridge. The main construction technologies of reinforced concrete arch bridges are also presented, which include cable-stayed fastening-hanging cantilever assembly, adjusting the load by means of stay cables, surrounding the concrete for arch rib pouring, and so forth. In addition, the construction of two CFST skeleton concrete arch bridges—the Guangxi Yongning Yong River Bridge and the Yunnan–Guangxi Railway Nanpan River Bridge—is discussed. CFST arch bridges in China have already gained a world-leading position; with the continuous innovation of key technologies, China will become the new leader in promoting the development of arch bridges. Keywords: Concrete-filled steel tube (CFST arch bridge, Steel-reinforced concrete arch bridge, Cable-stayed fastening-hanging cantilever assembly, Vacuum-assisted pouring in-tube concrete, Adjusting load by stay cables

  7. Fire Response of Concrete Filled Hollow Steel Sections

    DEFF Research Database (Denmark)

    Nyman, Simon; Virdi, Kuldeep

    2011-01-01

    Advanced and simplified methods of analysis and design for the fire resistance of structural elements and assemblages of structures have been developed in recent years. Some simplified methods for the fire design of concrete filled tubes have appeared in Eurocode 4 part 1.2. Experience to date in...... hollow sections....

  8. Steel hollow columns with an internal profile filled with self-compacting concrete under fire conditions

    OpenAIRE

    Chu, Thi Binh; Gernay, Thomas; Dotreppe, Jean-Claude; Franssen, Jean-Marc

    2016-01-01

    A detailed experimental and numerical investigation has been performed on the behavior under fire conditions of concrete filled steel hollow section (CFSHS) columns. In this study the internal reinforcement consists of another profile (tube or H section) being embedded with the concrete, and filling is realized by self-compacting concrete (SCC). Ten columns filled with self-compacting concrete embedding another steel profile have been tested in the Fire Testing Laboratory of the University of...

  9. Experimental investigation on temperature distribution of foamed concrete filled steel tube column under standard fire

    Science.gov (United States)

    Kado, B.; Mohammad, S.; Lee, Y. H.; Shek, P. N.; Kadir, M. A. A.

    2018-04-01

    Standard fire test was carried out on 3 hollow steel tube and 6 foamed concrete filled steel tube columns. Temperature distribution on the columns was investigated. 1500 kg/m3 and 1800 kg/m3 foamed concrete density at 15%, 20% and 25% load level are the parameters considered. The columns investigated were 2400 mm long, 139.7 mm outer diameter and 6 mm steel tube thickness. The result shows that foamed concrete filled steel tube columns has the highest fire resistance of 43 minutes at 15% load level and low critical temperature of 671 ºC at 25% load level using 1500 kg/m3 foamed concrete density. Fire resistance of foamed concrete filled column increases with lower foamed concrete strength. Foamed concrete can be used to provide more fire resistance to hollow steel column or to replace normal weight concrete in concrete filled columns. Since filling hollow steel with foamed concrete produce column with high fire resistance than unfilled hollow steel column. Therefore normal weight concrete can be substituted with foamed concrete in concrete filled column, it will reduces the self-weight of the structure because of its light weight at the same time providing the desired fire resistance.

  10. Numerical analysis of concrete-filled tubes with stiffening plates under large deformation axial loading

    OpenAIRE

    Albareda Valls, Albert

    2013-01-01

    Concrete-filled tubes have been increasingly used these recent decades thanks to their improved structural behavior, especially under compression.Concrete filling in these sections improves ¡ts compressive strength thanks to lateral pressure coming from confinement effect provided by the steel tube. At elevated percentages of loading,concrete suffers an important volumetric expansion, which is clearly restricted by the tube. Therefore, the core is subjected to a severe lateral pressure tha...

  11. Seismic behavior of conxl connections in concrete filled steel Tube ...

    African Journals Online (AJOL)

    This connection consists of collar flange, collar corner, and collar web extension. In this paper, the seismic behavior of these types of connections is investigated using the numerical method. For this purpose, three samples of ConXL connections without concrete filler, with concrete filler and with concrete filler and stiffener ...

  12. DOUBLE CURVED SURFACE (DCS) - Case study in reinforced concrete

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro; Henriques, Goncalo

    2007-01-01

    This paper deals with digital integration between design and fabrication in order to construct a complex double-curved concrete surface. This research focused on practical application of CNC technology to polyurethane (EPS), as an alternative to concrete formwork. The influence of specific EPS...

  13. Behavior of Hollow Thin Welded Tubes Filled with Sand Slag Concrete

    Directory of Open Access Journals (Sweden)

    Noureddine Ferhoune

    2016-01-01

    Full Text Available This paper presents the axial bearing capacity of thin welded rectangular steel stubs filled with concrete sand. A series of tests was conducted to study the behavior of short composite columns under axial compressive load; the cross section dimensions were 100 × 70 × 2 mm. A total of 20 stubs have been tested, as follows: 4 hollow thin welded tubes were tested to axial and eccentric load compression, 4 were filled with ordinary concrete appointed by BO columns, 6 were filled with concrete whose natural sand was completely substituted by a crystallized sand slag designated in this paper by BSI, and 6 were tucked in concrete whose natural sand was partially replaced by a crystallized sand slag called BSII. The main parameters studied are the height of the specimen (300 mm–500 mm, eccentricity of load and type of filling concrete. Based on test results obtained, it is confirmed that the length of the tubes has a considerable effect on the bearing capacity and the failure mode. In all test tubes, fracture occurred by the convex local buckling of steel section due to the outward thrust of the concrete; it was observed that the sand concrete improves the bearing capacity of tubes compounds compared to those filled with ordinary concrete.

  14. Behavior of FRP-Confined Concrete-Filled Steel Tube Columns

    Directory of Open Access Journals (Sweden)

    Yiyan Lu

    2014-05-01

    Full Text Available This paper presents the results of an experimental study into the behavior of concrete-filled steel tube columns confined by fiber-reinforced polymer (FRP. Eleven columns were tested to investigate the effects of the FRP layer number, the thickness of the steel tube and concrete strength on their load capacity and axial deformation capacity. The experimental results indicated that the FRP wrap can effectively confine the concrete expansion and delay the local buckling of the steel tube. Both the load capacity and the axial deformation capacity of concrete-filled steel tube columns can be substantially enhanced with FRP confinement. A model is proposed to predict the load capacity of the FRP-confined concrete-filled steel tube columns. The predicted results are generally in good agreement with the experimental ones obtained in this study and in the literature.

  15. Doubling the Life of Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Pesic, Batric [Univ. of Idaho, Moscow, ID (United States); Raja, Krishnan [Univ. of Idaho, Moscow, ID (United States); Xi, Yumping [Univ. of Colorado, Boulder, CO (United States); Jun, Jiheon [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-07-24

    Overall objective of the project was to study the fundamental properties of concrete (with and without steel reinforcement) with respect to chemical and physical parameters that can influence its structural integrity.

  16. Doubling the Life of Concrete Structures

    International Nuclear Information System (INIS)

    Pesic, Batric; Raja, Krishnan; Xi, Yumping; Jun, Jiheon

    2017-01-01

    Overall objective of the project was to study the fundamental properties of concrete (with and without steel reinforcement) with respect to chemical and physical parameters that can influence its structural integrity.

  17. Concrete Infill Monitoring in Concrete-Filled FRP Tubes Using a PZT-Based Ultrasonic Time-of-Flight Method.

    Science.gov (United States)

    Luo, Mingzhang; Li, Weijie; Hei, Chuang; Song, Gangbing

    2016-12-07

    Concrete-filled fiber-reinforced polymer tubes (CFFTs) have attracted interest for their structural applications in corrosive environments. However, a weak interfacial strength between the fiber-reinforced polymer (FRP) tube and the concrete infill may develop due to concrete shrinkage and inadequate concrete compaction during concrete casting, which will destroy the confinement effect and thereby reduce the load bearing capacity of a CFFT. In this paper, the lead zirconate titanate (PZT)-based ultrasonic time-of-flight (TOF) method was adopted to assess the concrete infill condition of CFFTs. The basic idea of this method is that the velocity of the ultrasonic wave propagation in the FRP material is about half of that in concrete material. Any voids or debonding created along the interface between the FRP tube and the concrete will delay the arrival time between the pairs of PZT transducers. A comparison of the arrival times of the PZT pairs between the intact and the defected CFFT was made to assess the severity of the voids or the debonding. The feasibility of the methodology was analyzed using a finite-difference time-domain-based numerical simulation. Experiments were setup to validate the numerical results, which showed good agreement with the numerical findings. The results showed that the ultrasonic time-of-flight method is able to detect the concrete infill condition of CFFTs.

  18. Concrete Infill Monitoring in Concrete-Filled FRP Tubes Using a PZT-Based Ultrasonic Time-of-Flight Method

    Science.gov (United States)

    Luo, Mingzhang; Li, Weijie; Hei, Chuang; Song, Gangbing

    2016-01-01

    Concrete-filled fiber-reinforced polymer tubes (CFFTs) have attracted interest for their structural applications in corrosive environments. However, a weak interfacial strength between the fiber-reinforced polymer (FRP) tube and the concrete infill may develop due to concrete shrinkage and inadequate concrete compaction during concrete casting, which will destroy the confinement effect and thereby reduce the load bearing capacity of a CFFT. In this paper, the lead zirconate titanate (PZT)-based ultrasonic time-of-flight (TOF) method was adopted to assess the concrete infill condition of CFFTs. The basic idea of this method is that the velocity of the ultrasonic wave propagation in the FRP material is about half of that in concrete material. Any voids or debonding created along the interface between the FRP tube and the concrete will delay the arrival time between the pairs of PZT transducers. A comparison of the arrival times of the PZT pairs between the intact and the defected CFFT was made to assess the severity of the voids or the debonding. The feasibility of the methodology was analyzed using a finite-difference time-domain-based numerical simulation. Experiments were setup to validate the numerical results, which showed good agreement with the numerical findings. The results showed that the ultrasonic time-of-flight method is able to detect the concrete infill condition of CFFTs. PMID:27941617

  19. Production and construction technology of C100 high strength concrete filled steel tube

    Science.gov (United States)

    Wu, Yanli; Sun, Jinlin; Yin, Suhua; Liu, Yu

    2017-10-01

    In this paper, the effect of the amount of cement, water cement ratio and sand ratio on compressive strength of C100 concrete was studied. The optimum mix ratio was applied to the concrete filled steel tube for the construction of Shenyang Huangchao Wanxin mansion. The results show that the increase of amount of cement, water cement ratio can improve the compressive strength of C100 concrete but increased first and then decreased with the increase of sand ratio. The compressive strength of C100 concrete can reach 110MPa with the amount of cement 600kg/m3, sand ratio 40% and water cement ratio 0.25.

  20. design chart procedures for polygonal concrete-filled steel columns

    African Journals Online (AJOL)

    ADMIN

    hexagonal and octagonal steel-concrete composite columns subjected to ... This paper also outlines procedures that will enable preparation of ... buildings and in a variety of large-span building ... Likewise, hot-rolled steel tubes are used while ... small moderate large. Fig. 2. Possible arrangement of composite polygonal ...

  1. High-impact concrete for fill in US Department of Transportation type shipping containers

    International Nuclear Information System (INIS)

    Greenhalgh, W.O.; Cash, R.J.

    1990-01-01

    This report describes the use of light-weight, high-impact concrete in U.S. Department of Transportation-type shipments. The formulations described are substantially lighter in weight (20 to 50 percent) than construction concrete, but product test specimens generally yield superior impact characteristics. The use of this specialty concrete for container fill, encapsulations, or liquid-waste solidification can be advantageous. Use of the material for container or cask construction has the advantage of lighter weight for easier handling, and the container consistently exhibits better performance on drop tests. High-impact concrete does have the disadvantage of less gamma radiation shielding per volume, but some formulation changes discussed in this report can be used to prepare better shielding concrete. Test characteristics of high-impact concrete are included. 3 refs., 6 figs., 7 tabs

  2. Numerical analysis on seismic behavior of reinforced concrete beam to concrete filled steel tubular column connections with ring-beam

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yi., E-mail: zhaoyi091218@163.com [School of Civil and Architectural Engineering, Zhongyuan University of Technology,Zhengzhou 450000 (China); Xu, Li. Hua. [School of Civil Engineering, Wuhan University, No.8, Donghu Road, WuHan 430072 (China)

    2016-06-08

    This paper presents numerical study of the seismic behavior of reinforced concrete beam to concrete filled steel tube column connections with ring-beam. The material stress-strain relations, element type and boundary condition are selected, which are consistent with actual situation. Then the seismic behavior of this type of joint are researched by ABAQUS, and finite element analyses are conducted under cyclic loading. Its parameters are discussed including thickness of steel tubular column wall, sectional dimension of the ring-beam and strength of the core concrete. The results show that the ultimate capacity of the connections is improved with sectional dimension of the ring-beam increased. In the meanwhile, the influence on skeleton curve of the joints is slight of which included thickness of steel tubular column wall and strength of the core concrete.

  3. PZT-Based Detection of Compactness of Concrete in Concrete Filled Steel Tube Using Time Reversal Method

    Directory of Open Access Journals (Sweden)

    Shi Yan

    2014-01-01

    Full Text Available A smart aggregate-based approach is proposed for the concrete compactness detection of concrete filled steel tube (CFST columns. The piezoceramic-based smart aggregates (SAs were embedded in the predetermined locations prior to the casting of concrete columns to establish a wave-based smart sensing system for the concrete compactness detection purpose. To evaluate the efficiency of the developed approach, six specimens of the CFST columns with the rectangular cross-section were produced by placing some artificial defects during casting of concrete for simulating various uncompacted voids such as cavities, cracks, and debond. During the test, the time reversal technology was applied to rebuild the received signals and launch the reversed signals again by SAs, to overcome the issue of the lack of the prototype. Based on the proposed nonprototype, two indices of time reversibility (TR and symmetry (SYM were applied to relatively evaluate the level of concrete compactness in the range of the two SAs. The experimental results show that the developed method can effectively detect the compactness of concrete in CFST columns.

  4. Concrete Cracking Prediction Including the Filling Proportion of Strand Corrosion Products

    Science.gov (United States)

    Wang, Lei; Dai, Lizhao; Zhang, Xuhui; Zhang, Jianren

    2016-01-01

    The filling of strand corrosion products during concrete crack propagation is investigated experimentally in the present paper. The effects of stirrups on the filling of corrosion products and concrete cracking are clarified. A prediction model of crack width is developed incorporating the filling proportion of corrosion products and the twisting shape of the strand. Experimental data on cracking angle, crack width, and corrosion loss obtained from accelerated corrosion tests of concrete beams are presented. The proposed model is verified by experimental data. Results show that the filling extent of corrosion products varies with crack propagation. The rust filling extent increases with the propagating crack until a critical width. Beyond the critical width, the rust-filling extent remains stable. Using stirrups can decrease the critical crack width. Stirrups can restrict crack propagation and reduce the rust filling. The tangent of the cracking angle increases with increasing corrosion loss. The prediction of corrosion-induced crack is sensitive to the rust-filling extent. PMID:28772367

  5. Organic geochemistry and stable isotope composition of New Zealand carbonate concretions and calcite fracture fills

    International Nuclear Information System (INIS)

    Pearson, M.J.; Nelson, C.S.

    2005-01-01

    Carbonate concretion bodies, representing a number of morphological types, and associated calcite fracture fills, mainly from New Zealand, have been studied both organically and inorganically. Extracted organic material is dominated by a complex polymeric dark brown highly polar fraction with a subordinate less polar and lighter coloured lipid fraction. The relative proportion of the two fractions is the principal control on the colour of fracture fill calcites. Concretions are classified mainly by reference to their carbonate stable carbon and oxygen isotope and cation composition. Typical subspherical calcitic septarian concretions, such as those in the Paleocene Moeraki and the Eocene Rotowaro Siltstones, contain carbon derived mainly by bacterial sulfate reduction in marine strata during early diagenesis. Other concretions, including a septarian calcitic type from the Northland Allochthon, have a later diagenetic origin. Siderite concretions, abundant in the nonmarine Waikato Coal Measures, are typically dominated by methanogenic carbon, whereas paramoudra-like structures from the Taranaki Miocene have the most extreme carbon isotope compositions, probably resulting from methane formation or oxidation in fluid escape conduits. Lipids from concretion bodies and most fracture fill calcites contain significant concentrations of fatty acids. Concretion bodies dominated by bimodally distributed n-fatty acids with strong even-over-odd preference, in which long chain n-acids are of terrestrial origin, have very low hydrocarbon biomarker maturities. Concretion bodies that lack long chain n-acids often have higher apparent biomarker maturity and prominent alpha-omega diacids. Such diacids are abundant in fracture fill calcites at Rotowaro, especially where calcite infills the septaria of a siderite concretion in the non-marine Waikato Coal Measures, and support the view that fluid transport resulted in carbonate entrapment of the fracture-hosted acids. Diacids also

  6. Processing method of radiation concrete waste and manufacturing method for radioactive waste solidifying filling mortar

    International Nuclear Information System (INIS)

    Sukekiyo, Mitsuaki; Okamoto, Masamichi

    1998-01-01

    Radioactive concrete wastes are crushed and pulverized. Fine solid granular materials caused by the pulverization are classified and the grain size is controlled so that the maximum grain size is 2.5mm, with the grains having a grain size of up to 0.15mm being up to 30% by weight to form fine aggregates. Separated and recovered fine concrete powders are classified and the size of the powder is controlled within a range of from 3,000 to 15,000cm 2 /g which is smaller than cement particles to form fine powders having a stable quality suitable as a mixing agent. The fine aggregates and the mixing agent are mixed to form a filling mortar (filler) for solidifying radioactive wastes. The filling mortar is filled together with other radioactive wastes in a drum to form a waste body in a drum. With such a constitution, crushed radioactive concrete wastes can be reutilized completely. (I.N.)

  7. Utilization of crushed radioactive concrete for mortar to fill waste container void space

    International Nuclear Information System (INIS)

    Ishikura, Takeshi; Ohnishi, Kazuhiko; Oguri, Daiichiro; Ueki, Hiroyuki

    2004-01-01

    Minimizing the volume of radioactive waste generated during dismantling of nuclear power plants is a matter of great importance. In Japan waste forms buried in a shallow burial disposal facility as low level radioactive waste must be solidified by cement or other materials with adequate strength and must provide no harmful opening. The authors have developed an improved method to minimize radioactive waste volume by utilizing radioactive concrete for fine aggregate for mortars to fill void space in waste containers. Tests were performed with pre-placed concrete waste and with filling mortar using recycled fine aggregate produced from concrete. It was estimated that the improved method substantially increases the waste fill ratio in waste containers, thereby decreasing the total volume of disposal waste. (author)

  8. Mini Seminar on Form Filling Ability of Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2005-01-01

    The Nordic mini-seminar “Form Filling Ability of Self-Compacting Concrete” took place on 3-4 November 2003 at the Danish Technological Institute in Taastrup, Denmark. The mini-seminar gathered 12 participants from Finland, Sweden, Norway and Denmark. The objective was to present and discuss recent...... developments of Self-Compacting Concrete in the Nordic countries. In general, the seminar included results and observations on the effect of fresh concrete behaviour, casting technique, and organisation on site on the filling ability, passing ability, and surface quality. The seminar had participants from...

  9. Comparison of the performance of concrete-filled steel tubular and hollow steel diagrid buildings

    Science.gov (United States)

    Peter, Minu Ann; S, Sajith A.; Nagarajan, Praveen

    2018-03-01

    In the recent construction scenario, diagrid structures are becoming a popular high-rise building structural system. Diagrid structures consist of diagonals in the perimeter and an interior core. The corner and interior vertical columns are not required due to the structural efficiency of diagrid structural systems. Steel and concrete are commonly used material for diagrid. An alternate material for diagrid is concrete-filled steel tube (CFST). CFST incorporates the advantages of both steel and concrete. In CFST, the inward buckling of the steel tube is effectively prevented by the filled concrete. The compressive strength of concrete increases due to the tri-axial state of stress in concrete induced by the steel tube. The longitudinal as well as lateral reinforcement to the concrete core is also provided by the steel tube. This paper compares the performance of CFST and steel diagrid buildings using linear static analysis. For this purpose, a 12 storey and 36 storey building are analysed using finite element method and CFST diagrid building is found to perform better.

  10. Investigation of Stress-Strain-Time Relationships of Concrete Filled Steel Tube Columns

    Directory of Open Access Journals (Sweden)

    Mutlu Seçer

    2010-01-01

    Full Text Available In this study, time dependent creep and shrinkage behaviors of concrete filled steel box section columns are investigated by using various methods. Time dependent behavior is examined by using effective modulus method, age-adjusted effective modulus method, creep rate method and Dischinger method. Shrinkage and creep strains are modeled using ACI 209 specification. In the study, in order to investigate time dependent behavior numerically, a concrete filled steel box section column is selected in a twenty story building and the time dependent stress decrease in concrete and stress increase in steel box section and the changes in strain components are calculated. Stress – time, strain – time and strain components – time graphics are shown and the advantages and the disadvantages of the numerical methods in modeling the time dependent behavior are revealed respectively.

  11. Testing refractory concretes and filling masses using laboratory gas dynamic bench

    International Nuclear Information System (INIS)

    Delkin, E.Ya.; Krasnikov, A.V.; Kurtepova, O.I.; Chubarov, Yu.I.

    1983-01-01

    Heat resistance of cylindrical models of refractory concretes on the base of different binding and filling masses at one-side heating is investigated. Heat resistance has been estimated by residual tensile strength. Concrete on the base of barium zirconate is shown to have the highest heat resistance. The effect of relation of the diameter and height of cylindrical samples on the value of thermal stresses arising at one-side heating is displayed on the example of concrete on phosphate binding. Tests of binding mass on the base of ZrO 2 reinforced with metallic honeycombs have revealed that use of copper honeycomb frame in elements of the design operating under the effect of strong thermal flows is rather effective

  12. Mechanical Behavior of Recycled Aggregate Concrete-Filled Steel Tubular Columns before and after Fire

    Directory of Open Access Journals (Sweden)

    Wenchao Liu

    2017-03-01

    Full Text Available Recycled aggregate concrete (RAC is an environmentally friendly building material. This paper investigates the mechanical behavior of recycled aggregate concrete filled steel tube (RACFST columns exposed to fire. Two groups of 12 columns were designed and tested, under axial compression, before and after fire, to evaluate the degradation of bearing capacity due to fire exposure. Six specimens were subjected to axial compression tests at room temperature and the other six specimens were subjected to axial compression tests after a fire exposure. The main parameters of the specimens include the wall thickness of the steel tube (steel content and the type of concrete materials. Several parameters as obtained from the experimental results were compared and analyzed, including the load-bearing capacity, deformation capacity, and failure characteristics of the specimens. Meanwhile, rate of loss of bearing capacity of specimens exposed to fire were calculated based on the standards EC4 and CECS28:90. The results show that concrete material has a large influence on the rate of loss of bearing capacity in the case of a relatively lower steel ratio. While steel content has little effect on the rate of loss of bearing capacity of concrete-filled steel tube (CFST columns after fire, it has a relatively large influence on the loss rate of bearing capacity of the RACFST columns. The loss of bearing capacity of the specimens from the experiment is more serious than that from the calculation. As the calculated values are less conservative, particular attention should be given to the application of recycled aggregate concrete in actual structures.

  13. Mechanical Behavior of Recycled Aggregate Concrete-Filled Steel Tubular Columns before and after Fire.

    Science.gov (United States)

    Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Wang, Ruwei; Ren, Lele

    2017-03-09

    Recycled aggregate concrete (RAC) is an environmentally friendly building material. This paper investigates the mechanical behavior of recycled aggregate concrete filled steel tube (RACFST) columns exposed to fire. Two groups of 12 columns were designed and tested, under axial compression, before and after fire, to evaluate the degradation of bearing capacity due to fire exposure. Six specimens were subjected to axial compression tests at room temperature and the other six specimens were subjected to axial compression tests after a fire exposure. The main parameters of the specimens include the wall thickness of the steel tube (steel content) and the type of concrete materials. Several parameters as obtained from the experimental results were compared and analyzed, including the load-bearing capacity, deformation capacity, and failure characteristics of the specimens. Meanwhile, rate of loss of bearing capacity of specimens exposed to fire were calculated based on the standards EC4 and CECS28:90. The results show that concrete material has a large influence on the rate of loss of bearing capacity in the case of a relatively lower steel ratio. While steel content has little effect on the rate of loss of bearing capacity of concrete-filled steel tube (CFST) columns after fire, it has a relatively large influence on the loss rate of bearing capacity of the RACFST columns. The loss of bearing capacity of the specimens from the experiment is more serious than that from the calculation. As the calculated values are less conservative, particular attention should be given to the application of recycled aggregate concrete in actual structures.

  14. Proposals for Calculation of Bucking Coefficient for Concrete-Filled Steel Tube Columns

    Science.gov (United States)

    Krishan, A. L.; Sagadatov, A. I.; Surovtsov, M. M.

    2017-11-01

    This paper demonstrates that the methodology currently standardized in Russia to factor in the flexibility of reinforced concrete components under extra-central compression produce results that satisfactorily match the experimental values; however, that only holds for the components with a flexibility of λ=40÷60. Given the complex stress state of the concrete core and the steel shell as well as due to the concrete-filled steel tube columns being prone to deformation, this method cannot be used to reliably calculate their load capacity. The literature review has revealed many researchers’ suggestions to factor in the flexibility of concrete-filled steel tubes by means of the buckling coefficient that reduces the limit value of longitudinal force a short compressed element can take. We have analyzed the methods currently standardized in Europe and China as well as more advanced methods proposed by Chinese scientists. Calculating by these methods led to the results that excessively deviated from experimental values. By statistically analyzing a large volume of own and third-party research data as well as the data obtained by non-linear deformation computing, we have derived a new formula to determine the bucking coefficient depending on the relative flexibility.

  15. An Experimental Study on Shrinkage Strains of Normal-and High-Strength Concrete-Filled Frp Tubes

    Science.gov (United States)

    Vincent, Thomas; Ozbakkaloglu, Togay

    2017-09-01

    It is now well established that concrete-filled fiber reinforced polymer (FRP) tubes (CFFTs) are an attractive construction technique for new columns, however studies examining concrete shrinkage in CFFTs remain limited. Concrete shrinkage may pose a concern for CFFTs, as in these members the curing of concrete takes place inside the FRP tube. This paper reports the findings from an experimental study on concrete shrinkage strain measurements for CFFTs manufactured with normal- and high-strength concrete (NSC and HSC). A total of 6 aramid FRP (AFRP)-confined concrete specimens with circular cross-sections were manufactured, with 3 specimens each manufactured using NSC and HSC. The specimens were instrumented with surface and embedded strain gauges to monitor shrinkage development of exposed concrete and concrete sealed inside the CFFTs, respectively. All specimens were cylinders with a 152 mm diameter and 305 mm height, and their unconfined concrete strengths were 44.8 or 83.2 MPa. Analysis of the shrinkage measurements from concrete sealed inside the CFFTs revealed that embedment depth and concrete compressive strength only had minor influences on recorded shrinkage strains. However, an analysis of shrinkage measurements from the exposed concrete surface revealed that higher amounts of shrinkage can occur in HSC. Finally, it was observed that shrinkage strains are significantly higher for concrete exposed at the surface compared to concrete sealed inside the CFFTs.

  16. Self-sensing concrete-filled FRP tube using FBG strain sensor

    Science.gov (United States)

    Yan, Xin; Li, Hui

    2007-01-01

    Concrete-filled fiber-reinforced polymer (FRP) tube is a type of newly developed structural column. It behaves brittle failure at its peak strength, and so the health monitoring on the hoop strain of the FRP tube is essential for the life cycle safety of the structure. Herein, the optic fiber Bragg grating (FBG) strain sensor was chosen as the strain measuring gauge and embedded in the inter-ply of fibers in the middle height and the hoop direction of the FRP tube. The compressive behaviors of the concrete-filled FRP tubes were experimentally studied. The hoop strain of the FRP tube was recorded in real time using the embedded FBG strain sensor as well as the embedded or surface electric resistance strain gauges. Results indicated that the FBG strain sensor can faithfully record the hoop strain ofthe concrete-filled FRP tubes in compression as compared with the embedded or surface electric resistance strain gauges, and the strain recorded can reach more than 7000μɛ.

  17. Biaxial bending of slender HSC columns and tubes filled with concrete under short- and long-term loads: I Theory

    Directory of Open Access Journals (Sweden)

    Jose A. Rodríguez-Gutiérrez

    2014-05-01

    Full Text Available An analytical method that calculates both the short- and long-term response of slender columns made of high-strength concrete (HSC and tubes filled with concrete with generalized end conditions and subjected to transverse loads along the span and axial load at the ends (causing a single or double curvature under uniaxial or biaxial bending is presented. The proposed method, which is an extension of a method previously developed by the authors, is capable of predicting not only the complete load-rotation and load-deflection curves (both the ascending and descending parts but also the maximum load capacity. The columns that can be analyzed include solid and hollow (rectangular, circular, oval, C-, T-, L-, or any arbitrary shape cross sections and columns made of circular and rectangular steel tubes filled with HSC. The fiber method is used to calculate the moment-curvature diagrams at different levels of the applied axial load (i.e., the M-P-φ curves, and the Gauss method of integration (for the sum of the contributions of the fibers parallel to the neutral axis is used to calculate the lateral rotations and deflections along the column span. Long-term effects, such as creep and shrinkage of the concrete, are also included. However, the effects of the shear deformations and torsion along the member are not included. The validity of the proposed method is presented in a companion paper and compared against the experimental results for over seventy column specimens reported in the technical literature by different researchers.

  18. On the performance of circular concrete-filled high strength steel columns under axial loading

    Directory of Open Access Journals (Sweden)

    Mohamed Mahmoud El-Heweity

    2012-06-01

    Full Text Available This work presents a numerical study to investigate the performance of circular high-strength steel tubes filled with concrete (CFT under monotonic axial loading. A model is developed to implement the material constitutive relationships and non-linearity. Calibration against previous experimental data shows good agreement. A parametric study is then conducted using the model and compared with codes provisions. Strength and ductility of confined concrete are of primary concern. Variables considered are yield stress of steel tube and column diameter. The assessment of column performance is based on axial load carrying capacities and enhancements of both strength and ductility due to confinement. Two parameters namely strength enhancement factor (Kf and ductility index (μ are clearly defined and introduced for assessment. Results indicate that both concrete strength and ductility of CFT columns are enhanced but to different extents. The ductile behaviors are significantly evident. The increase in yield stress of steel tube has a minimal effect on concrete strength but pronounced effect on concrete ductility. However, reduction in ductility is associated with using high-tensile steel of Grade 70. The overall findings indicate that the use of high-strength tube in CFT columns is not promising. This finding may seriously be considered in seismic design.

  19. The use of concrete-filled steel structures for modular construction of advanced reactors

    International Nuclear Information System (INIS)

    Braverman, J.; Morante, R.; Hofmayer, C.; Graves, H.

    1997-01-01

    Modular construction techniques have been successfully used in a number of industries, both domestically and internationally. Recently, the use of structural modules has been proposed for advanced nuclear power plants. This paper presents the results of a research program which evaluated the use of modular construction for safety-related structures in advanced nuclear power plant designs. The research program included review of current modular construction technology, development of licensing review criteria for modular construction, and initial validation of currently available analytical techniques applied to concrete-filled steel structural modules

  20. Parametric Study of Fire Performance of Concrete Filled Hollow Steel Section Columns with Circular and Square Cross-Section

    Science.gov (United States)

    Nurfaidhi Rizalman, Ahmad; Tahir, Ng Seong Yap Mahmood Md; Mohammad, Shahrin

    2018-03-01

    Concrete filled hollow steel section column have been widely accepted by structural engineers and designers for high rise construction due to the benefits of combining steel and concrete. The advantages of concrete filled hollow steel section column include higher strength, ductility, energy absorption capacity, and good structural fire resistance. In this paper, comparison on the fire performance between circular and square concrete filled hollow steel section column is established. A three-dimensional finite element package, ABAQUS, was used to develop the numerical model to study the temperature development, critical temperature, and fire resistance time of the selected composite columns. Based on the analysis and comparison of typical parameters, the effect of equal cross-sectional size for both steel and concrete, concrete types, and thickness of external protection on temperature distribution and structural fire behaviour of the columns are discussed. The result showed that concrete filled hollow steel section column with circular cross-section generally has higher fire resistance than the square section.

  1. Development and Substantiation of Parameters of Environmentally Friendly Technology for Filling the Vertical Mine Workings with Autoclaved Slag-Concrete

    Directory of Open Access Journals (Sweden)

    Uglyanitca Andrey

    2017-01-01

    Full Text Available The environmentally friendly technology for filling the vertical mine workings with autoclaved slag-concrete, prefabricated on the surface of the mine is presented in the article; the optimal parameters of filling technology are proposed. The developed technology for filling the abandoned vertical mine workings allows ensuring the environmental safety of the territories adjacent to the abandoned mine, utilizing slag dumps and providing the possibility of shaft recovery, if necessary, with minimal labor and material costs.

  2. Performance of Retrofitted Self-Compacting Concrete-Filled Steel Tube Beams Using External Steel Plates

    Directory of Open Access Journals (Sweden)

    Ahmed A. M. AL-Shaar

    2018-01-01

    Full Text Available Self-compacting concrete-filled steel tube (SCCFST beams, similar to other structural members, necessitate retrofitting for many causes. However, research on SCCFST beams externally retrofitted by bolted steel plates has seldom been explored in the literature. This paper aims at experimentally investigating the retrofitting performance of square self-compacting concrete-filled steel tube (SCCFST beams using bolted steel plates with three different retrofitting schemes including varied configurations and two different steel plate lengths under flexure. A total of 18 specimens which consist of 12 retrofitted SCCFST beams, three unretrofitted (control SCCFST beams, and three hollow steel tubes were used. The flexural behaviour of the retrofitted SCCFST beams was examined regarding flexural strength, failure modes, and moment versus deflection curves, energy absorption, and ductility. Experimental results revealed that the implemented retrofitting schemes efficiently improve the moment carrying capacity and stiffness of the retrofitted SCCFST beams compared to the control beams. The increment in flexural strength ranged from 1% to 46%. Furthermore, the adopted retrofitting schemes were able to restore the energy absorption and ductility of the damaged beams in the range of 35% to 75% of the original beam ductility. Furthermore, a theoretical model was suggested to predict the moment capacity of the retrofitted SCCFST beams. The theoretical model results were in good agreement with the test results.

  3. Experiment on interface separation detection of concrete-filled steel tubular arch bridge using accelerometer array

    Science.gov (United States)

    Pan, Shengshan; Zhao, Xuefeng; Zhao, Hailiang; Mao, Jian

    2015-04-01

    Based on the vibration testing principle, and taking the local vibration of steel tube at the interface separation area as the study object, a real-time monitoring and the damage detection method of the interface separation of concrete-filled steel tube by accelerometer array through quantitative transient self-excitation is proposed. The accelerometers are arranged on the steel tube area with or without void respectively, and the signals of accelerometers are collected at the same time and compared under different transient excitation points. The results show that compared with the signal of compact area, the peak value of accelerometer signal at void area increases and attenuation speed slows down obviously, and the spectrum peaks of the void area are much more and disordered and the amplitude increases obviously. whether the input point of transient excitation is on void area or not is irrelevant with qualitative identification results. So the qualitative identification of the interface separation of concrete-filled steel tube based on the signal of acceleration transducer is feasible and valid.

  4. Self-sensing concrete-filled FRP tubes using FBG strain sensors

    Science.gov (United States)

    Yan, Xin; Li, Hui

    2007-07-01

    Concrete-filled fiber-reinforced polymer (FRP) tube is a type of newly developed structural column. It behaves brittle failure at its peak strength, and so the health monitoring on the hoop strain of the FRP tube is essential for the life cycle safety of the structure. Herein, three types of FRP tubes including 5-ply tube, 2-ply tube with local reinforcement and FRP-steel composite tube were embedded with the optic fiber Bragg grating (FBG) strain sensors in the inter-ply of FRP or the interface between FRP and steel in the middle height and the hoop direction. The compressive behaviors of the concrete-filled FRP tubes were experimentally studied. The hoop strains of the FRP tubes were recorded in real time using the embedded FBG strain sensors as well as the embedded or surface electric resistance strain gauges. Results indicated that the FBG strain sensors can faithfully record the hoop strains of the FRP tubes in compression as compared with the embedded or surface electric resistance strain gauges, and the strains recorded can reach more than μɛ.

  5. Damage assessment for seismic response of recycled concrete filled steel tube columns

    Science.gov (United States)

    Huang, Yijie; Xiao, Jianzhuang; Shen, Luming

    2016-09-01

    A model for evaluating structural damage of recycled aggregate concrete filled steel tube (RCFST) columns under seismic effects is proposed in this paper. The proposed model takes the lateral deformation and the effect of repeated cyclic loading into account. Available test results were collected and utilized to calibrate the parameters of the proposed model. A seismic test for six RCFST columns was also performed to validate the proposed damage assessment model. The main test parameters were the recycled coarse aggregate (RCA) replacement percentage and the bond-slip property. The test results indicated that the seismic performance of the RCFST member depends on the RCA contents and their damage index increases as the RCA replacement percentage increases. It is also indicated that the damage degree of RCFST changes with the variation of the RCA replacement percentage. Finally, comparisons between the RCA contents, lateral deformation ratio and damage degree were implemented. It is suggested that an improvement procedure should be implemented in order to compensate for the performance difference between the RCFST and normal concrete filled steel tubes (CFST).

  6. Steel-reinforced concrete-filled steel tubular columns under axial and lateral cyclic loading

    Science.gov (United States)

    Farajpourbonab, Ebrahim; Kute, Sunil Y.; Inamdar, Vilas M.

    2018-03-01

    SRCFT columns are formed by inserting a steel section into a concrete-filled steel tube. These types of columns are named steel-reinforced concrete-filled steel tubular (SRCFT) columns. The current study aims at investigating the various types of reinforcing steel section to improve the strength and hysteresis behavior of SRCFT columns under axial and lateral cyclic loading. To attain this objective, a numerical study has been conducted on a series of composite columns. First, FEM procedure has been verified by the use of available experimental studies. Next, eight composite columns having different types of cross sections were analyzed. For comparison purpose, the base model was a CFT column used as a benchmark specimen. Nevertheless, the other specimens were SRCFT types. The results indicate that reinforcement of a CFT column through this method leads to enhancement in load-carrying capacity, enhancement in lateral drift ratio, ductility, preventing of local buckling in steel shell, and enhancement in energy absorption capacity. Under cyclic displacement history, it was observed that the use of cross-shaped reinforcing steel section causes a higher level of energy dissipation and the moment of inertia of the reinforcing steel sections was found to be the most significant parameter affecting the hysteresis behavior of SRCFT columns.

  7. Grout compactness monitoring of concrete-filled fiber-reinforced polymer tube using electromechanical impedance

    Science.gov (United States)

    Shi, Yaokun; Luo, Mingzhang; Li, Weijie; Song, Gangbing

    2018-05-01

    The concrete-filled fiber-reinforced polymer tube (CFFT) is a type of structural element widely used in corrosive environments. Poor grout compactness results in incomplete contact or even no contact between the fiber-reinforced polymer (FRP) tube and the concrete grout, which reduces the load bearing capacity of a CFFT. The monitoring of grout compactness for CFFTs is important. The piezoceramic-based electromechanical impedance (EMI) method has emerged as an efficient and low-cost structural health monitoring technique. This paper presents a feasibility study using the EMI method to monitor grout compactness of CFFTs. In this research, CFFT specimens with different levels of compactness (empty, 1/5, 1/3, 1/2, 2/3, and full compactness) were prepared and subjected to EMI measurement by using four piezoceramic patches that were bonded circumferentially along the outer surface of the CFFT. To analyze the correlation between grout compactness and EMI signatures, a compactness index (CI) was proposed based on the root-mean-square deviation (RMSD). The experimental results show that the changes in admittance signatures are able to determine the grout compactness qualitatively. The proposed CI is able to effectively identify the compactness of the CFFT, and provides location information of the incomplete concrete infill.

  8. A compression and shear loading test of concrete filled steel bearing wall

    International Nuclear Information System (INIS)

    Akiyama, Hiroshi; Sekimoto, Hisashi; Fukihara, Masaaki; Nakanishi, Kazuo; Hara, Kiyoshi.

    1991-01-01

    Concrete-filled steel bearing walls called SC structure which are the composite structure of concrete and steel plates have larger load-carrying capacity and higher ductility as compared with conventional RC structures, and their construction method enables the rationalization of construction procedures at sites and the shortening of construction period. Accordingly, the SC structures have become to be applied to the inner concrete structures of PWR nuclear power plants, and subsequently, it is planned to apply them to the auxiliary buildings of nuclear power plants. The purpose of this study is to establish a rational design method for the SC structures which can be applied to the auxiliary buildings of nuclear power plants. In this study, the buckling strength of surface plates and the ultimate strength of the SC structure were evaluated with the results of the compression and shear tests which have been carried out. The outline of the study and the tests, the results of the compression test and the shear test and their evaluation are reported. Stud bolts were effective for preventing the buckling of surface plates. The occurrence of buckling can be predicted analytically. (K.I.)

  9. Development of Lateral Prestress in High-Strength Concrete-Filled FRP Tubes

    Science.gov (United States)

    Vincent, T.; Ozbakkaloglu, T.

    2018-02-01

    This paper reports on an experimental investigation into the axial and lateral strain development of fiber reinforced polymer (FRP) confined high-strength concrete (HSC) with prestressed FRP shells. A total of 24 aramid FRP (AFRP)-confined concrete specimens were manufactured as concrete-filled FRP tubes (CFFTs) with instrumentation to measure the strain variations during application of prestress, removal of end constraints and progressive prestress losses. Prestressed CFFT specimens were prepared with three different dose rates of expansive mineral admixture to create a range of lateral prestress applied to AFRP tubes manufactured with sheet thicknesses of 0.2 or 0.3 mm/ply and referred to as lightly- or well-confined, respectively. In addition to these three levels of prestress, non-prestressed companion specimens were manufactured and tested to determine baseline performance. The experimental results from this study indicate that lateral prestressing of CFFTs manufactured with HSC can be achieved by varying the expansive mineral admixture dose rate with a lateral prestress of up to 7.3 MPa recorded in this study. Significant strain variations were measured during removal of the end constraints with up to 700 microstrain recorded in the axial direction. Finally, the measurement of prestress losses for the month following prestress application revealed minimal progressive losses, with only 250 and 100 με recorded for the axial and hoop strains, respectively.

  10. Finite Element Analysis and Crashworthiness Optimization of Foam-filled Double Circular under Oblique Loading

    Directory of Open Access Journals (Sweden)

    Fauzan Djamaluddin

    Full Text Available Abstract Finite element analysis and optimization design carry out for the quasi static responses of foam-filled double circular tube is presented in this paper. In the investigation of the crashworthiness capability, some aspects were considered for variations in geometry parameters of tubes and the loading condition to investigate the crashworthiness capability. Empty, foam-filled, and full foam-filled doublé tubes of thin walled structures were observed subjected to oblique impact (0˚ - 40˚. The numerical solution was used to determine the crashworthiness parameters. In addition, NSGA II and Radial Basis Function were used to optimize the crashworthiness capability of tubes. In conclution, the crash performaces of foam-filled double tube is better than the other structures in this work. The outcome that expected is the new design information of various kinds of cylindrical tubes for energy absorber application.

  11. STRESS-STRAIN STATE OF ROCKFILL DAM DOUBLE-LAYER FACE MADE OF REINFORCED CONCRETE AND SOIL-CEMENT CONCRETE

    Directory of Open Access Journals (Sweden)

    Sainov Mikhail Petrovich

    2017-05-01

    Full Text Available There was studied the stress-strain state of 215 m high rockfill dam where the seepage-control element is presented by a reinforced concrete face of soil-cement concrete placed on the under-face zone. Calculations were carried out for two possible variants of deformability of rock outline taking into account the non-linearity of its deformative properties. It was obtained that the reinforced concrete face and the soil-cement concrete under-face zone work jointly as a single construction - a double-layer face. As the face assembly resting on rock is made with a sliding joint the scheme of its static operation is similar to the that of the beam operation on the elastic foundation. At that, the upstream surface of the double-layer face is in the compressed zone and lower one is in the tensile zone. This protects the face against cracking on the upstream surface but threatens with structural failure of soil-cement concrete. In order to avoid appearance of cracks in soil-cement concrete part due to tension it is necessary to achieve proper compaction of rockfill and arrange transverse joints in the double-layer face.

  12. Construction Simulation Analysis of 60m-span Concrete Filled Steel Tube arch bridge

    Science.gov (United States)

    Shi, Jing Xian; Ding, Qing Hua

    2018-06-01

    The construction process of the CFST arch bridge is complicated. The construction process not only affects the structural stress in the installation, but also determines the form a bridge and internal force of the bridge. In this paper, a 60m span concrete filled steel tube tied arch bridge is taken as the background, and a three-dimensional finite element simulation model is established by using the MIDAS/Civil bridge structure analysis software. The elevation of the main arch ring, the beam stress, the forces in hanger rods and the modal frequency of the main arch during the construction stage are calculated, and the construction process is simulated and analyzed. Effectively and reasonably guide the construction and ensure that the line and force conditions of the completed bridge meet the design requirements and provides a reliable technical guarantee for the safe construction of the bridge.

  13. Empirical Approach for Determining Axial Strength of Circular Concrete Filled Steel Tubular Columns

    Science.gov (United States)

    Jayalekshmi, S.; Jegadesh, J. S. Sankar; Goel, Abhishek

    2018-03-01

    The concrete filled steel tubular (CFST) columns are highly regarded in recent years as an interesting option in the construction field by designers and structural engineers, due to their exquisite structural performance, with enhanced load bearing capacity and energy absorption capacity. This study presents a new approach to simulate the capacity of circular CFST columns under axial loading condition, using a large database of experimental results by applying artificial neural network (ANN). A well trained network is established and is used to simulate the axial capacity of CFST columns. The validation and testing of the ANN is carried out. The current study is focused on proposing a simplified equation that can predict the ultimate strength of the axially loaded columns with high level of accuracy. The predicted results are compared with five existing analytical models which estimate the strength of the CFST column. The ANN-based equation has good prediction with experimental data, when compared with the analytical models.

  14. Seismic performance of recycled concrete-filled square steel tube columns

    Science.gov (United States)

    Chen, Zongping; Jing, Chenggui; Xu, Jinjun; Zhang, Xianggang

    2017-01-01

    An experimental study on the seismic performance of recycled concrete-filled square steel tube (RCFST) columns is carried out. Six specimens were designed and tested under constant axial compression and cyclic lateral loading. Two parameters, replacement percentage of recycled coarse aggregate (RCA) and axial compression level, were considered in the test. Based on the experimental data, the hysteretic loops, skeleton curves, ductility, energy dissipation capacity and stiffness degradation of RCFST columns were analyzed. The test results indicate that the failure modes of RCFST columns are the local buckling of the steel tube at the bottom of the columns, and the hysteretic loops are full and their shapes are similar to normal CFST columns. Furthermore, the ductility coefficient of all specimens are close to 3.0, and the equivalent viscous damping coefficient corresponding to the ultimate lateral load ranges from 0.323 to 0.360, which demonstrates that RCFST columns exhibit remarkable seismic performance.

  15. Empirical Approach for Determining Axial Strength of Circular Concrete Filled Steel Tubular Columns

    Science.gov (United States)

    Jayalekshmi, S.; Jegadesh, J. S. Sankar; Goel, Abhishek

    2018-06-01

    The concrete filled steel tubular (CFST) columns are highly regarded in recent years as an interesting option in the construction field by designers and structural engineers, due to their exquisite structural performance, with enhanced load bearing capacity and energy absorption capacity. This study presents a new approach to simulate the capacity of circular CFST columns under axial loading condition, using a large database of experimental results by applying artificial neural network (ANN). A well trained network is established and is used to simulate the axial capacity of CFST columns. The validation and testing of the ANN is carried out. The current study is focused on proposing a simplified equation that can predict the ultimate strength of the axially loaded columns with high level of accuracy. The predicted results are compared with five existing analytical models which estimate the strength of the CFST column. The ANN-based equation has good prediction with experimental data, when compared with the analytical models.

  16. Discrimination of high-Z materials in concrete-filled containers using muon scattering tomography

    Science.gov (United States)

    Frazão, L.; Velthuis, J.; Thomay, C.; Steer, C.

    2016-07-01

    An analysis method of identifying materials using muon scattering tomography is presented, which uses previous knowledge of the position of high-Z objects inside a container and distinguishes them from similar materials. In particular, simulations were performed in order to distinguish a block of Uranium from blocks of Lead and Tungsten of the same size, inside a concrete-filled drum. The results show that, knowing the shape and position from previous analysis, it is possible to distinguish 5 × 5 × 5 cm3 blocks of these materials with about 4h of muon exposure, down to 2 × 2 × 2 cm3 blocks with 70h of data using multivariate analysis (MVA). MVA uses several variables, but it does not benefit the discrimination over a simpler method using only the scatter angles. This indicates that the majority of discrimination is provided by the angular information. Momentum information is shown to provide no benefits in material discrimination.

  17. Modeling of high-strength concrete-filled FRP tube columns under cyclic load

    Science.gov (United States)

    Ong, Kee-Yen; Ma, Chau-Khun; Apandi, Nazirah Mohd; Awang, Abdullah Zawawi; Omar, Wahid

    2018-05-01

    The behavior of high-strength concrete (HSC) - filled fiber-reinforced-polymer (FRP) tubes (HSCFFTs) column subjected to cyclic lateral loading is presented in this paper. As the experimental study is costly and time consuming, a finite element analysis (FEA) is chosen for the study. Most of the previous studies have focused on examining the axial load behavior of HSCFFT column instead of seismic behavior. The seismic behavior of HSCFFT columns has been the main interest in the industry. The key objective of this research is to develop a reliable numerical non-linear FEA model to represent the seismic behavior of such column. A FEA model was developed using the Concrete Damaged Plasticity Model (CDPM) available in the finite element software package (ABAQUS). Comparisons between experimental results from previous research and the predicted results were made based on load versus displacement relationships and ultimate strength of the column. The results showed that the column increased in ductility and able to deform to a greater extent with the increase of the FRP confinement ratio. With the increase of confinement ratio, HSCFFT column achieved a higher moment resistance, thus indicated a higher failure strength in the column under cyclic lateral load. It was found that the proposed FEA model can regenerate the experimental results with adequate accuracy.

  18. Study on Axial Compressive Capacity of FRP-Confined Concrete-Filled Steel Tubes and Its Comparisons with Other Composite Structural Systems

    Directory of Open Access Journals (Sweden)

    Jun Deng

    2017-01-01

    Full Text Available Concrete-filled steel tubular (CFST columns have been widely used for constructions in recent decades because of their high axial strength. In CFSTs, however, steel tubes are susceptible to degradation due to corrosion, which results in the decrease of axial strength of CFSTs. To further improve the axial strength of CFST columns, carbon fiber reinforced polymer (CFRP sheets and basalt fiber reinforced polymer (BFRP sheets are applied to warp the CFSTs. This paper presents an experimental study on the axial compressive capacity of CFRP-confined CFSTs and BFRP-confined CFSTs, which verified the analytical model with considering the effect of concrete self-stressing. CFSTs wrapped with FRP exhibited a higher ductile behavior. Wrapping with CFRP and BFRP improves the axial compressive capacity of CFSTs by 61.4% and 17.7%, respectively. Compared with the previous composite structural systems of concrete-filled FRP tubes (CFFTs and double-skin tubular columns (DSTCs, FRP-confined CFSTs were convenient in reinforcing existing structures because of softness of the FRP sheets. Moreover, axial compressive capacity of CFSTs wrapped with CFRP sheets was higher than CFFTs and DSTCs, while the compressive strength of DSTCs was higher than the retrofitted CFSTs.

  19. Thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes

    International Nuclear Information System (INIS)

    Yang Jian; Hu Yu; Zuo Zheng; Jin Feng; Li Qingbin

    2012-01-01

    Removal of hydration heat from mass concrete during construction is important for the quality and safety of concrete structures. In this study, a three-dimensional finite element program for thermal analysis of mass concrete embedded with double-layer staggered heterogeneous cooling water pipes was developed based on the equivalent equation of heat conduction including the effect of cooling water pipes and hydration heat of concrete. The cooling function of the double-layer staggered heterogeneous cooling pipes in a concrete slab was derived from the principle of equivalent cooling. To improve the applicability and precision of the equivalent heat conduction equation under small flow, the cooling function was revised according to its monotonicity and empirical formulas of single-phase forced-convection heat transfer in tube flow. Considering heat hydration of concrete at later age, a double exponential function was proposed to fit the adiabatic temperature rise curve of concrete. Subsequently, the temperature variation of concrete was obtained, and the outlet temperature of cooling water was estimated through the energy conservation principle. Comparing calculated results with actual measured data from a monolith of an arch dam in China, the numerical model was proven to be effective in sufficiently simulating accurate temperature variations of mass concrete. - Highlights: ► Three-dimensional program is developed to model temperature history of mass concrete. ► Massive concrete is embedded with double-layer heterogeneous cooling pipes. ► Double exponential function is proposed to fit the adiabatic temperature rise curve. ► Outlet temperature of cooling water is estimated. ► A comparison is made between the calculated and measured data.

  20. Experimental evaluation and design of unfilled and concrete-filled FRP composite piles : Task 7 : final report : thesis.

    Science.gov (United States)

    2015-05-01

    The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP composite piles for load-bearing in bridges. This report covers Task 7, Final Report - Thesis. : This final report covers Tasks 1, 2, 3, 5 ...

  1. Experimental analysis of energy absorption behaviour of Al-tube filled with pumice lightweight concrete under axial loading condition

    Science.gov (United States)

    Rajak, D. K.; Deshpande, P. G.; Kumaraswamidhas, L. A.

    2017-08-01

    This Paper aimed at experimental investigation of compressive behaviour of square tube filled with pumice lightweight concrete (PLC). Square section of 20×20×30 mm is investigated, which is the backbone structure. The compression deformation result shows the better folding mechanism, displacement value, and energy absorption. PLC concrete filled with aluminium thin-wall tubes has been revealed superior energy absorption capacity (EAC) under low strain rate at room temperature. Superior EAC resulted as a result of mutual deformation benefit between aluminium section and PLC is also analysed. PLC was characterised by Fourier Transform Infrared (FTIR) and Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray Spectrometry (EDX) analysis for better understanding of material behaviour. Individual and comparative load bearing graphs is logged for better prospective of analysing. Novel approach aimed at validation of porous lightweight concrete for better lightweight EA filler material.

  2. Integral procedure to assess crack filling and mechanical contribution of polymer-based healing agent in encapsulation-based self-healing concrete

    NARCIS (Netherlands)

    Gilabert Villegas, Francisco Antonio; Van Tittelboom, Kim; Van Stappen, J.; Cnudde, Veerle; De Belie, Nele; Van Paepegem, Wim

    2017-01-01

    This work presents an experimental and numerical study to analyze the crack filling process in encapsulation-based self-healing concrete. A specimen consisting of two small concrete blocks has been designed containing capsules filled with a polyurethane-based healing agent. This design enables to

  3. Thermoelectric properties of high pressure synthesized lithium and calcium double-filled CoSb3

    Directory of Open Access Journals (Sweden)

    Xiaohui Li

    2017-01-01

    Full Text Available Lithium and calcium are inefficient filling elements of CoSb3 at ambient pressure, but show nice filling behavior under high pressure. In this work, we synthesized Li/Ca double-filled CoSb3 with high pressure synthesis method. The products show the skutterudite structure of Im3¯ symmetry. Thermoelectric properties were effectively enhanced through Li and Ca co-filling. For the optimal Li0.08Ca0.18Co4Sb12 sample, the power factor maintains a relatively high value over the whole measurement temperature range and peaks at 4700μWm−1K−2, meanwhile the lattice thermal conductivity is greatly suppressed, leading to a maximal ZT of 1.18 at 700 K. Current work demonstrates high pressure synthesis as an effective method to produce multiple elemental filled CoSb3 skutterudites.

  4. Experimental Study on Superfine Sand Concrete Mixed by Double Mixing Technology

    OpenAIRE

    yuqing zhao

    2013-01-01

    Traditional concept thought that medium sand and fine sand can be used to mix concrete, superfine sand can not used to mix concrete. This makes the source of superfine sand limited. With the shortage of medium sand and fine sand, it is imperative to exploit the resource of superfine sand. Superfine sand concrete is mixed by means of Double-doped Technology-ultra-fine fly ash and super plasticizer. Primary factor influencing superfine sand concrete strength is studied by orthogonal test, the o...

  5. Concrete Instantiations of Mathematics: A Double-Edged Sword

    Science.gov (United States)

    Kaminski, Jennifer A.; Sloutsky, Vladimir M.; Heckler, Andrew F.

    2009-01-01

    What factors affect transfer of knowledge is a complex question. In recent research, the authors demonstrated that concreteness of the learning domain is one such factor (Kaminski, Sloutsky, & Heckler, 2008). Even when prompted and given no time delay, participants who learned a concrete instantiation of a mathematical concept failed to…

  6. Experimental Study of Concrete-filled Carbon Fiber Reinforced Polymer Tube with Internal Reinforcement under Axially Loading

    Directory of Open Access Journals (Sweden)

    Wenbin SUN

    2014-12-01

    Full Text Available Comparing with the circular concrete columns confined with fiber reinforced polymer (FRP wrap or tube, the rectilinear confined columns were reported much less. Due to the non-uniform distribution of confining pressure in the rectilinear confined columns, the FRP confinement effectiveness was significant reduced. This paper presents findings of an experimental program where nine prefabricated rectangular cross-section CFRP tubes with CFRP integrated crossties filled concrete to form concrete-filled FRP tube (CFFT short columns and three plain concrete control specimens were tested. All specimens were axially loaded until failure. The rest results showed that the stress-strain curves of CFFTs consisted of two distinct branches, an ascending branch before the concrete peak stress was reaches and a second branch that terminated when the tube ruptured, and that the CFFTs with integrated crossties experienced most uniform confinement pressure distribution. Test research also found that the stress-strain curves of CFFTs indicated an increase in ductility. These demonstrate that this confinement system can produce higher lateral confinement stiffness. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6035

  7. APPLICATION OF FLOW SIMULATION FOR EVALUATION OF FILLING-ABILITY OF SELF-COMPACTING CONCRETE

    Science.gov (United States)

    Urano, Shinji; Nemoto, Hiroshi; Sakihara, Kohei

    In this paper, MPS method was applied to fluid an alysis of self-compacting concrete. MPS method is one of the particle method, and it is suitable for the simulation of moving boundary or free surface problems and large deformation problems. The constitutive equation of self-compacting concrete is assumed as bingham model. In order to investigate flow Stoppage and flow speed of self-compacting concrete, numerical analysis examples of slump flow and L-flow test were performed. In addition, to evaluate verification of compactability of self-compacting concrete, numerical analys is examples of compaction at the part of CFT diaphragm were performed. As a result, it was found that the MPS method was suitable for the simulation of compaction of self-compacting concrete, and a just appraisal was obtained by setting shear strain rate of flow-limit πc and limitation point of segregation.

  8. Experimental evaluation and design of unfilled and concrete-filled FRP composite piles : Task 4B : material & construction specifications : final report.

    Science.gov (United States)

    2015-07-01

    The overall goal of this project is the experimental evaluation and design of unfilled and concrete-filled FRP composite piles for load-bearing in bridges. This report covers Task 4B, Materials and Construction Specifications. : This technical report...

  9. The influence of using accelerator addition on High strength self-compacting concrete (HSSCC) in case of enhancement early compressive strength and filling ability parameters

    Science.gov (United States)

    Wibowo; Fadillah, Y.

    2018-03-01

    Efficiency in a construction works is a very important thing. Concrete with ease of workmanship and rapid achievement of service strength will to determine the level of efficiency. In this research, we studied the optimization of accelerator usage in achieving performance on compressive strength of concrete in function of time. The addition of variation of 0.3% - 2.3% to the weight of cement gives a positive impact of the rapid achievement of hardened concrete, however the speed of increasing of concrete strength achievement in term of time influence present increasing value of filling ability parameter of self-compacting concrete. The right composition of accelerator aligned with range of the values standard of filling ability parameters of HSSCC will be an advantage guidance for producers in the ready-mix concrete industry.

  10. The 1500 MW fast breeder reactor the double envelope-vessel anchored in concrete

    International Nuclear Information System (INIS)

    Bolvin, M.

    1981-01-01

    This paper givers an account of EDF investigations to reduce the investment costs of the 1500 MW Fast Reactor (RNR 1500) without prejudice to the safety requirements. It deals with the double envelope-vessel, designed to minimize radiation consequences in the event of accidental leakage in the main vessel. In the Fast Reactors in operation (PHOENIX), under construction (CRYS-MALVILLE), and under project (NR 1500), the double envelope-steel vessel hangs down from the upper part of the reactor block, its weight being approximately 300 t. In the new design, the vessel is fixed into the concrete which supports the main vessel, by means of steel anchors. A thermal insulation isolates it from the main vessel. The installation of coils in the concrete, next to the lining, allows for water circulation to cool the concrete. (orig./GL)

  11. Optimization of the flexible mould process for the production of double-curved concrete elements

    NARCIS (Netherlands)

    Schipper, H.R.; Grunewald, S.; Eigenraam, P.; Raghunath, P.; Kok, M.

    2014-01-01

    Free-form buildings tend to be expensive. By optimizing the production process, economical and wellperforming concrete structures and elements can be manufactured. In this paper, an innovative method is presented that allows producing highly accurate double curved-elements without the need for

  12. Double-curved precast concrete elements : Research into technical viability of the flexible mould method

    NARCIS (Netherlands)

    Schipper, H.R.

    2015-01-01

    The production of precast, concrete elements with complex, double-curved geometry is expensive due to the high costcosts of the necessary moulds and the limited possibilities for mould reuse. Currently, CNC-milled foam moulds are the solution applied mostly in projects, offering good aesthetic

  13. Arch-Axis Coefficient Optimization of Long-Span Deck-Type Concrete-Filled Steel Tubular Arch Bridge

    Science.gov (United States)

    Liu, Q. J.; Wan, S.; Liu, H. C.

    2017-11-01

    This paper is based on Nanpuxi super major bridge which is under construction and starts from Wencheng Zhejiang province to Taishun highway. A finite element model of the whole bridge is constructed using Midas Civil finite element software. The most adverse load combination in the specification is taken into consideration to determine the method of calculating the arch-axis coefficient of long-span deck-type concrete-filled steel tubular arch bridge. By doing this, this paper aims at providing references for similar engineering projects.

  14. Pervious concrete fill in Pearl-Chain Bridges: Using small-scale results in full-scale implementation

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Truelsen, R.

    2016-01-01

    distribution and strength properties is determined for 800 mm high blocks cast in different numbers of layers, and (2) full-scale implementation in a 26 m long Pearl-Chain Bridge. With a layer thickness of 27 cm, the small-scale tests indicated homogenous results; however, for the full-scale implementation......Pearl-Chain Bridge technology is a new prefabricated arch solution for highway bridges. This study investigates the feasibility of pervious concrete as a filling material in Pearl-Chain Bridges. The study is divided into two steps: (1) small-scale tests where the variation in vertical void...

  15. Experimental Research on Seismic Performance of Four-Element Variable Cross-Sectional Concrete Filled Steel Tubular Laced Columns

    Science.gov (United States)

    Ou, Zhijing; Lin, Jianmao; Chen, Shengfu; Lin, Wen

    2017-10-01

    A total of 7 experimental tests were conducted to investigate seismic performance of four element variable cross-sectional Concrete Filled Steel Tubular (CFST) laced columns. The experimental parameters are longitudinal slope and arrangement type of lacing tubes. The rules on hysteresis loop, ductility, energy expenditure, and stiffness degradation of specimens are researched. Test results indicate that all specimens have good seismic performance; their hysteresis loops are full without obvious shrinkage. With the increase of longitudinal slope, the horizontal carrying capacity increases, energy dissipation capacity improve, and there is slightly increase in stiffness degradation. The influence of arrangement type of lacing tubes on displacement ductility of specimens is big.

  16. Development and Evaluation of Mould for Double Curved Concrete Elements

    DEFF Research Database (Denmark)

    Jepsen, Christian Raun; Kristensen, Mathias Kræmmergaard; Kirkegaard, Poul Henning

    2011-01-01

    freeform concrete formwork are available, and more are being developed [1-4]. The common way of producing moulds for unique elements today is to manufacture one mould for each unique element using CNC milling in cheaper materials, but since the method is still labour intensive and produces a lot of waste......Complex freeform architecture is one of the most striking trends in contemporary architecture. Architecture differs from traditional target industries of CAD/CAM technology in many ways including aesthetics, statics, structural aspects, scale and manufacturing technologies. Designing a piece...... of freeform architecture in a CAD program is fairly easy, but the translation to a real piece of architecture can be difficult and expensive and as traditional production methods for free-form architecture prove costly, architects and engineers are forced to simplify designs. Today, methods for manufacturing...

  17. Diffusion and Leaching Behavior of Radionuclides in Category 3 Waste Encasement Concrete and Soil Fill Material – Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Mattigod, Shas V.; Wellman, Dawn M.; Bovaird, Chase C.; Parker, Kent E.; Clayton, Libby N.; Powers, Laura; Recknagle, Kurtis P.; Wood, Marcus I.

    2011-08-31

    One of the methods being considered for safely disposing of Category 3 low-level radioactive wastes is to encase the waste in concrete. Such concrete encasement would contain and isolate the waste packages from the hydrologic environment and would act as an intrusion barrier. The current plan for waste isolation consists of stacking low-level waste packages on a trench floor, surrounding the stacks with reinforced steel, and encasing these packages in concrete. These concrete-encased waste stacks are expected to vary in size with maximum dimensions of 6.4 m long, 2.7 m wide, and 4 m high. The waste stacks are expected to have a surrounding minimum thickness of 15 cm of concrete encasement. These concrete-encased waste packages are expected to withstand environmental exposure (solar radiation, temperature variations, and precipitation) until an interim soil cover or permanent closure cover is installed, and to remain largely intact thereafter. Any failure of concrete encasement may result in water intrusion and consequent mobilization of radionuclides from the waste packages. The mobilized radionuclides may escape from the encased concrete by mass flow and/or diffusion and move into the surrounding subsurface environment. Therefore, it is necessary to assess the performance of the concrete encasement structure and the ability of the surrounding soil to retard radionuclide migration. The retardation factors for radionuclides contained in the waste packages can be determined from measurements of diffusion coefficients for these contaminants through concrete and fill material. Some of the mobilization scenarios include (1) potential leaching of waste form before permanent closure cover is installed; (2) after the cover installation, long-term diffusion of radionuclides from concrete waste form into surrounding fill material; (3) diffusion of radionuclides from contaminated soils into adjoining concrete encasement and clean fill material. Additionally, the rate of

  18. Double-diffusive natural convection in an enclosure filled with nanofluid using ISPH method

    Directory of Open Access Journals (Sweden)

    Abdelraheem M. Aly

    2016-12-01

    Full Text Available The double-diffusive natural convection in an enclosure filled with nanofluid is studied using ISPH method. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. In addition the thermal energy equations include regular diffusion and cross-diffusion terms. In ISPH algorithm, a semi implicit velocity correction procedure is utilized and the pressure is implicitly evaluated by solving pressure Poisson equation. The results are presented with flow configurations, isotherms, concentration and nanoparticle volume fraction contours and average Nusselt and Sherwood numbers for different cases. The results from this investigation are well validated and have favorable comparisons with previously published results. It is found that, among all cases, a good natural convection can be obtained by considering the double diffusive case. An increase in Soret number accompanied by a decrease in Dufour number results in an increase in average Nusselt number and a decrease in average Sherwood number.

  19. Diffusion of iodine and Technetium-99 through waste encasement concrete and unsaturated soil fill material

    International Nuclear Information System (INIS)

    Mattigod, Shas V.; Whyatt, Greg A.; Serne, R. JEFFREY; Wood, Marcus I.; Hanchar, John M.; Stores-Gascoyne, Simcha; Lauren Browning

    2004-01-01

    An assessment of long-term performance of low level waste-enclosing cement grouts requires diffusivity data for radionuclide species such as, 129I and 99Tc. The diffusivity of radionuclides in soil and concrete media was collected by conducting soil-soil and concrete-soil half-cell experiments. The soil diffusivity coefficients for iodide were 7.03 x 10-8 cm2/s and 2.42 x 10-7 cm2/s for soils at 4% and 7% moisture contents, respectively. Iodide diffusivity in soil is a function of moisture content and is about an order of magnitude slower at lower moisture content. The soil diffusivity coefficients for 99Tc were 5.89 ± 0.80 x 10-8 cm2/s (4% moisture content) and 2.04 ± 0.57 x 10-7 cm2/s (7% moisture content), respectively. The soil diffusivity of iodide and 99Tc were similar in magnitude at both water contents, indicating that these ions have similar diffusion mechanisms in unsaturated coarse-textured Hanford soil. The diffusivity of iodide in concrete ranged from 2.07 x 10-14 cm2/s (4% soil moisture content) to 1.31 x 10-12 cm2/s (7% soil moisture content), indicating that under unsaturated soil moisture conditions, iodide diffusivity is highly sensitive to changing soil moisture conditions. Depending on the soil moisture content, the diffusivity of 99Tc in concrete ranged from 4.54 x 10-13 cm2/s to 8.02 x 10-12 cm2/s. At 4% soil moisture content, iodide diffused about 20 times more slowly than 99Tc, and at 7% soil moisture content, iodide in concrete diffused about 6 times slower than 99Tc

  20. Optimum design of large span concrete filled steel tubular arch bridge based on static, stability and modal analysis

    Institute of Scientific and Technical Information of China (English)

    赵长军; 胡隽; 徐兴

    2002-01-01

    A three-dimensional finite element model was established for a large span concrete filled steel tubular (CFST) arch bridge which is currently under construction. The arch rib, the spandrel columns, the prestressed concrete box-beam, the cast-in-situ concrete plate of bridge deck, the steel box-beam and the crossbeams connecting the two pieces of arch ribs, were modeled by three-dimensional Timoshenko beam elements (3DTBE). The suspenders were modeled by three-dimensional cable elements (3DCE). Both geometric nonlinearity and prestress effect could be included in each kind of element. At the same time a second finite element model with the same geometric and material properties excepted for the sectional dimension of arch rib was set up. Static dynamic analyses were performed to determine the corresponding characteristics of the structure. The results showed that the arch rib's axial rigidity could be determined by static analysis. The stability and vibration of this system could be separated into in-plane modes, out-of-plane modes and coupled modes. The in-plane stability and dynamic characteristics are determined by the arch rib's vertical stiffness and that of out-of-plane is determined by the crossbeams' stiffness and arch rib's lateral stiffness mainly. The in-plane stiffness is much greater than that of out-of-plane for this kind of bridge . The effect of geometric nonlinearity and prestress effect on bridge behavior is insignificant.

  1. A PVDF-Based Sensor for Internal Stress Monitoring of a Concrete-Filled Steel Tubular (CFST) Column Subject to Impact Loads.

    Science.gov (United States)

    Du, Guofeng; Li, Zhao; Song, Gangbing

    2018-05-23

    Impact loads can have major adverse effects on the safety of civil engineering structures, such as concrete-filled steel tubular (CFST) columns. The study of mechanical behavior and stress analysis of CFST columns under impact loads is very important to ensure their safety against such loads. At present, the internal stress monitoring of the concrete cores CFST columns under impact loads is still a very challenging subject. In this paper, a PVDF (Polyvinylidene Fluoride) piezoelectric smart sensor was developed and successfully applied to the monitoring of the internal stress of the concrete core of a CFST column under impact loads. The smart sensor consists of a PVDF piezoelectric film sandwiched between two thin steel plates through epoxy. The protection not only prevents the PVDF film from impact damages but also ensures insulation and waterproofing. The smart sensors were embedded into the circular concrete-filled steel tube specimen during concrete pouring. The specimen was tested against impact loads, and testing data were collected. The time history of the stress obtained from the PVDF smart sensor revealed the evolution of core concrete internal stress under impact loads when compared with the impact force⁻time curve of the hammer. Nonlinear finite element simulations of the impact process were also carried out. The results of FEM simulations had good agreement with the test results. The results showed that the proposed PVDF piezoelectric smart sensors can effectively monitor the internal stress of concrete-filled steel tubular columns under impact loads.

  2. Simulation and Verification of Form Filling with Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2005-01-01

    This paper presents a form filling experiment and the corresponding 3D simulation. One side of the form is made of a transparent acrylic plate and to improve the visual observations of the flow behaviour, the first and second half of the form is cast with normal grey and red-pigmented SCC, respec...

  3. Visualizing and simulating flow conditions in concrete form filling using pigments

    DEFF Research Database (Denmark)

    Jacobsen, Stefan; Cepuritis, Rolands; Peng, Ya

    2013-01-01

    Flow variation at surfaces and reinforcement during form filling was visualized with grey and black SCC. The border between grey and black (pigmented) SCC was captured as frozen images on hardened sawn- and formwork surfaces in a flow box experiment. Maximum velocity occurred at the centre of the...

  4. Mechanical behavior of the reinforced concrete frame with masonry filling Comportement mécanique des portiques en béton armé avec remplissage en maçonnerie

    Directory of Open Access Journals (Sweden)

    Kettar Jalal

    2018-01-01

    The analysis of frames filled with masonry is very complex. This complexity is linked from one part to the difference in the nature of elements and its behavior that make up the masonry itself (brick and mortar and their interaction, and on the other part, for the large dispersion that characterizes the bricks as well as the execution's quality parameters which make it difficult to define reliable criteria for the masonry. The objective of this work is to experimentally highlight the influence of the hollow brick masonry filler, commonly used in Morocco, on reinforced concrete frames subject to lateral stresses, to deepen understanding the seismic behavior of the masonry structures by evaluating the structural performance of a specimen wall. These experimental results will be compared to those found by modeling prototypes, using SAP 2000 software, based on various approaches and models as well as other results deduced from the other researchers. The experimental study was carried out according to standard NF EN 1052-3 on two reinforced concrete frames, of dimensions (2m X 1.6m, the one with the masonry filling, and the other without filling in order to determine the initial characteristic resistance to the shearing of the masonry walls. The obtained results showed that a filling has a beneficial effect on rigidity which can be doubled compared to an empty frame. in the same way the lateral resistance. But this effect is much contrasted; it depends a lot on the characteristics essentially of the materials (bricks and concrete. This is the main reason, which justifies the divergence of the results deduced from the nine models that we used.

  5. Concrete

    DEFF Research Database (Denmark)

    2015-01-01

    Concrete is a component of coherent transition between a concrete base and a wooden construction. The structure is based on a quantity of investigations of the design possibilities that arise when combining digital fabrication tools and material capacities. Through tangible experiments the project...... specific for this to happen. And the knowledge and intention behind the drawing becomes specialised through the understanding of the fabrication processes and their affect on the materials.The structure Concrete is a result of a multi-angled kerf series in ash wood and a concrete base. The ash wood is cut...... using a 5-axis CNC router with a thin saw blade attached. The programming of the machining results in variations of kerfs that lets the ash wood twist into unique shapes.The shapes of the revolving ash ribbons continue into the concrete creating a cohesive shape. The form for the concrete itself is made...

  6. A method for filling in the cohesive ends of double-stranded DNA using Pfu DNA polymerase.

    Science.gov (United States)

    Yang, Shaohui; Li, Xin; Ding, Dongfeng; Hou, Jianhua; Jin, Zhaoxia; Yu, Xinchun; Bo, Tao; Li, Weidong; Li, Minggang

    2005-12-01

    The present paper reports a highly efficient method of making blunt ends from cohesive ends of double-stranded DNA. Klenow fragment and Pfu DNA polymerases were used to fill in the cohesive ends. Since the transformation efficiency can directly reflect the filling-in efficiency, similar ligation and transformation conditions were used, and the filling-in efficiency was compared with the corresponding transformation efficiency. The results indicate that the filling-in efficiency of Pfu DNA polymerase was 1.96 times that of Klenow fragment and its efficiency was markedly higher than that of Klenow fragment (P<0.01). The optimization experiments on reaction conditions indicate, when the pH is 8.5 and the temperature is 74 degrees C, that the filling-in efficiency was highest upon using a buffer containing 3 mM MgSO4 and 300 microM dNTP.

  7. Bridge-in-a-backpack(TM) task 3.3 : investigate soil-structure interaction-modeling and experimental results of concrete filled FRP tube arches.

    Science.gov (United States)

    2015-12-01

    This report includes fulfillment of Task 3.3 of a multi-task contract to further enhance concrete filled FRP tubes, or : the Bridge in a Backpack. Task 3 is an investigation of soil-structure interaction for the FRP tubes. Task 3.3 is the : modeling ...

  8. Investigation of in-plane moment connections of I-beams to square concrete-filled steel tube columns under gravity loads

    Directory of Open Access Journals (Sweden)

    Abdelrahim K. Dessouki

    2015-04-01

    Full Text Available This paper focuses on experimental and analytical behavior of the ultimate moment of the connections of steel I-beams to square concrete-filled steel tube columns. External stiffeners around the columns are used at the beam flange levels. Five specimens are tested monotonically. The test parameters are the column stiffener dimensions and filling the steel tube column with concrete. Two types of failure modes are observed; beam flange failure and stiffener failure. The experimental results show that the ultimate moment of the connection is increased by increasing stiffener’s dimensions and filling the steel tube column with concrete. ANSYS finite element program is used to simulate the behavior, taking into account both geometric and material nonlinearities. Analytical results that are in fair agreement with the experimental ones are then used to discuss the influence of the main geometric parameters on the connection behavior. The parameters are the stiffener and column dimensions as well as filling the steel tube column with concrete. Different square column cross sections are chosen to cover the three classes of section classifications according to Egyptian code of practice, which are: compact, non compact or slender. The increase in the ultimate moment of the connections is based upon both column cross sections’ compactness and stiffener dimensions while the maximum advantages occur with slender columns.

  9. Concrete

    OpenAIRE

    Kruse Aagaard, Anders

    2015-01-01

    Concrete is a component of coherent transition between a concrete base and a wooden construction. The structure is based on a quantity of investigations of the design possibilities that arise when combining digital fabrication tools and material capacities.Through tangible experiments the project discusses materiality and digitally controlled fabrications tools as direct expansions of the architect’s digital drawing and workflow. The project sees this expansion as an opportunity to connect th...

  10. Evaluating a steel beam’s rigid connection to a concrete filled tubular column when submitted to dynamic load

    Directory of Open Access Journals (Sweden)

    Maritza Uribe Vallejo

    2009-01-01

    Full Text Available Using prequalified connections during the structural design stage becomes increasingly necessary when developing structural en-gineering projects which include steel elements; this is so that the steel elements’ appropriate behavior can be ensured according to the structural system and seismic demand. Unfortunately, the international entities providing this type of information (i.e. FEMA only have a limit series of prequalified connections and such series do not include rigid connections between steel beams and concrete filled tubular (CFT columns having an extended end plate, which has become a very widespread building practice in Colombia. This paper describes the most important aspects of a study at the Universidad Nacional de Colombia concerning the behavior of a steel beam rigidly connected to a CFT-column, using six physical models having different width-thickness ratio (b/t columns. ANSYS v.10 software was used for studying theoretical models (finite elements analysis for comparative analysis of cyclic test theoretical and experimental results for each specimen presented for the qualification phase. The six tested specimens’ hysteretic curves are presented. Several conclusions are drawn concerning finite element validation for this type of connection and the influence of width-thickness ratio (b/t variation and design recommendations for suitable behavior under dynamic loads when this type of connection was used.

  11. 装填材料对PELE侵彻混凝土效能影响研究%Influence of filling material on penetration of PELE into concrete target

    Institute of Scientific and Technical Information of China (English)

    范少博; 陈智刚; 郭光全; 侯秀成; 陈冬梅

    2012-01-01

    为研究惰性装填物对PELE侵彻混凝土靶板效能影响,利用有限元软件LS-DYNA对不同惰性装填物的PELE侵彻混凝土靶板进行数值模拟.结果表明:与PELE侵彻混凝土靶板相比钢靶的形成破片质量较大、速度较慢;不同装填物对靶板的破坏效能不同;尼龙装填物比橡胶对靶板破坏的面积大,破片数量多.通过实验验证了模拟结果的正确性和可靠性.%Researches on the influence of inert fillings on penetration of PELE into concrete targets were carried out Penetration of PELE with different inert fillings into concrete targets was simulated by LS-DYNA. The results show that the fragments formed by penetration into concrete targets are larger and the velocity is lower than those into steel targets, and the different fillings have different damage efficiency. The damage area and the amount of fragments are larger for nylon filling material than for rubber. Correctness and reliability of the simulation results are verified by experiments.

  12. Long-Term and Seismic Performance of Concrete-Filled Steel Tube Columns with Conventional and High-Volume SCM Concrete

    Science.gov (United States)

    2012-06-01

    Production of Portland Cement for concrete is a major source of CO2 emission. Concrete can be made more sustainable by replacing a large volume of the cement with Supplementary Cementitous Materials (SCMs) such as fly ash and slag. The amount of ceme...

  13. Evaluating potential chlorinated methanes degradation mechanisms and treatments in interception trenches filled with concrete-based construction wastes

    Science.gov (United States)

    Rodríguez-Fernandez, Diana; Torrentó, Clara; Rosell, Mònica; Audí-Miró, Carme; Soler, Albert

    2014-05-01

    A complex mixture of chlorinated organic compounds is located in an unconfined carbonated bedrock aquifer with low permeability in a former industrial area next to Barcelona (NE Spain). The site exhibited an especially high complexity due to the presence of multiple contaminant sources, wide variety of pollutants (mainly chlorinated ethenes but also chlorinated methanes) and unknown system of fractures (Palau et al., 2014). Interception trenches were installed in the place of the removed pollution sources and were filled with construction wastes with the aim of retaining and treating the accumulated contaminated recharge water before reaching the aquifer. Recycled concrete-based aggregates from a construction and demolition waste recycling plant were used to maintain alkaline conditions in the water accumulated in the trenches (pH 11.6±0.3) and thus induce chloroform (CF) degradation by alkaline hydrolysis. An efficacy of around 30-40% CF degradation in the interception trenches was calculated from the significant and reproducible CF carbon isotopic fractionation (-53±3o obtained in batch experiments (Torrentó et al., 2014). Surprisingly, although hydrolysis of carbon tetrachloride (CT) is extremely slow, a significant CT carbon isotopic enrichment was also observed in the trenches. The laboratory experiments verified the low capability of concrete to hydrolyze the CT and showed the high adsorption of CT on the concrete particles (73% after 50 days) with invariability in its δ13C values. Therefore, the significant CT isotopic fractionation observed in the interception trenches could point out the occurrence of other degradation processes distinct than alkaline hydrolysis. Geochemical speciation modelling using the code PHREEQC showed that water collected at the trenches is supersaturated with respect to several iron oxy-hydroxides and therefore, CT degradation processes related to these iron minerals cannot be discarded. In addition, the combination of alkaline

  14. Analysis of radioactivity increase of rad waste filled in fibre-reinforced concrete container regarding external exposure of workers

    International Nuclear Information System (INIS)

    Baratova, D.; Hrncir, T.; Necas, V.

    2012-01-01

    The paper deals with the assessment of the external radiation exposure of workers performing the individual tasks associated with disposal of the fibre-reinforced concrete containers in the National Radioactive Waste Repository in Mochovce. Models for fibre-reinforced concrete containers with maximum activity allowable for transport and for fibre-reinforced concrete containers contained radionuclides at the common level of activity concentration were created in order to analyze the option of fibre-reinforced concrete containers radioactivity increase. Calculations of individual effective doses have been carried out for three workers who work in the control area of the waste disposal facility dosimetrist, assistant and crane worker. (Authors)

  15. Enhancement of thermoelectric efficiency of CoSb3-based skutterudites by double filling with K and Tl

    Directory of Open Access Journals (Sweden)

    Ken eKurosaki

    2014-10-01

    Full Text Available The high-temperature thermoelectric properties of thallium (Tl and potassium (K double-filled cobalt antimonide (CoSb3-based skutterudites with nominal compositions TlxK0.3Co4Sb12 (x = 0.1–0.3 were investigated. The filling fraction of Tl in CoSb3 was enhanced by co-filling with K, which resulted in all of the samples showing the filled-skutterudite single phase. Owing to the high filling ratio, the carrier concentration in the sample with x = 0.3 was as high as 4.3 × 1020 cm−3 at room temperature. Furthermore, quite low lattice thermal conductivity (as low as 0.9 W m−1 K−1 was obtained for the sample with x = 0.3, probably because of strong phonon scattering by the Tl and K co-rattling effect, which resulted in a maximum zT of around one at 773 K.

  16. Maximum credibly yield for deuteriuim-filled double shell imaging targets meeting requirements for yield bin Category A

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Douglas Carl [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Loomis, Eric Nicholas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-08-17

    We are anticipating our first NIF double shell shot using an aluminum ablator and a glass inner shell filled with deuterium shown in figure 1. The expected yield is between a few 1010 to a few 1011 dd neutrons. The maximum credible yield is 5e+13. This memo describes why, and what would be expected with variations on the target. This memo evaluates the maximum credible yield for deuterium filled double shell capsule targets with an aluminum ablator shell and a glass inner shell in yield Category A (< 1014 neutrons). It also pertains to fills of gas diluted with hydrogen, helium (3He or 4He), or any other fuel except tritium. This memo does not apply to lower z ablator dopants, such as beryllium, as this would increase the ablation efficiency. This evaluation is for 5.75 scale hohlraum targets of either gold or uranium with helium gas fills with density between 0 and 1.6 mg/cc. It could be extended to other hohlraum sizes and shapes with slight modifications. At present only laser pulse energies up to 1.5 MJ were considered with a single step laser pulse of arbitrary shape. Since yield decreases with laser energy for this target, the memo could be extended to higher laser energies if desired. These maximum laser parameters of pulses addressed here are near the edge of NIF’s capability, and constitute the operating envelope for experiments covered by this memo. We have not considered multiple step pulses, would probably create no advantages in performance, and are not planned for double shell capsules. The main target variables are summarized in Table 1 and explained in detail in the memo. Predicted neutron yields are based on 1D and 2D clean simulations.

  17. Is Detrusor Contraction during Rapid Bladder Filling Caused by Cold or Warm Water? A Randomized, Controlled, Double-Blind Trial.

    Science.gov (United States)

    Kozomara, Marko; Mehnert, Ulrich; Seifert, Burkhardt; Kessler, Thomas M

    2018-01-01

    We investigated whether detrusor contraction during rapid bladder filling is provoked by cold or warm water. Patients with neurogenic lower urinary tract dysfunction were included in this randomized, controlled, double-blind trial. At the end of a standard urodynamic investigation patients underwent 2 bladder fillings using a 4C ice water test or a 36C warm water test saline solution at a filling speed of 100 ml per minute. The order was randomly selected, and patients and investigators were blinded to the order. The primary outcome measure was detrusor overactivity, maximum detrusor pressure and maximum bladder filling volume during the ice and warm water tests. Nine women and 31 men were the subject of data analysis. Neurogenic lower urinary tract dysfunction was caused by spinal cord injury in 33 patients and by another neurological disorder in 7. Irrespective of test order detrusor overactivity occurred significantly more often during the ice water test than during the warm water test (30 of 40 patients or 75% vs 25 of 40 or 63%, p = 0.02). When comparing the ice water test to the warm water test, maximum detrusor pressure was significantly higher and maximum bladder filling volume was significantly lower during the ice water test (each p warm water first) had no effect on the parameters. Our findings imply that the more frequent detrusor overactivity, higher maximum detrusor pressure and lower bladder filling volume during the ice water test compared to the warm water test were caused by cold water. This underlies the theory of a C-fiber mediated bladder cooling reflex in humans. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  18. Layered double hydroxide-like materials: nanocomposites for use in concrete

    International Nuclear Information System (INIS)

    Raki, L.; Beaudoin, J.J.; Mitchell, L.

    2004-01-01

    Nitrobenzoic acid (NBA), naphthalene-2, 6-disulfonic acid (26NS), and naphthalene-2 sulfonic acid (2NS) salts were intercalated into a layered double hydroxide-like host material (LDH). The intercalation process was achieved by anion exchange of nitrates in the host material, Ca 2 Al(OH) 6 NO 3 , nH 2 O (CaAl LDH), which was prepared by a coprecipitation technique. The resulting organo derivatives CaAlNBA LDH, CaAl26NS LDH, and CaAl2NS LDH produced a tilted orientation of NBA and 26NS anions in the interlayer space, while 2NS anions induced a perpendicular bilayer arrangement. Materials characterization was carried out using X-ray diffraction (XRD), IR-spectroscopy, thermal analysis, and scanning electron microscopy (SEM). These preliminary results open up a new direction towards the synthesis of nanocomposites using polymeric entities and layered materials for future applications in cement and concrete science, e.g., control of the effect of admixtures on the kinetics of cement hydration by programming their temporal release

  19. Quantitative evaluation of compactness of concrete-filled fiber-reinforced polymer tubes using piezoceramic transducers and time difference of arrival

    Science.gov (United States)

    Xu, Yang; Luo, Mingzhang; Hei, Chuang; Song, Gangbing

    2018-03-01

    Owing to its light weight and corrosion resistance, the concrete-filled fiber-reinforced polymer tube (CFFT) structure has a broad application prospect; the concrete compactness is key to the strength of CFFTs. To meet the urgent requirement of compactness monitoring of CFFTs, a quantitative method, which uses an array of four equally spaced piezoceramic patches and an ultrasonic time difference of arrival (TDOA) algorithm, is developed. Since the velocity of the ultrasonic wave propagation in fiber-reinforced polymer (FRP) material is about half of that in concrete material, the compactness condition of CFFT impacts the piezoceramic-induced wave propagation in the CFFT, and differentiates the TDOA for different receivers. An important condition is the half compactness, which can be judged by the Half Compactness Indicator (HCI) based on the TDOAs. To characterize the difference of stress wave propagation durations from the emitter to different receivers, which can be utilized to calculate the concrete infill compactness, the TDOA ratio (TDOAR) is introduced. An innovative algorithm is developed in this paper to estimate the compactness of the CFFT using HCI and TDOAR values. Analytical, numerical, and experimental studies based on a CFFT with seven different states of compactness (empty, 1/10, 1/3, 1/2, 2/3, 9/10, and full) are carried out in this research. Analyses demonstrate that there is a good agreement among the analytical, numerical, and experimental results of the proposed method, which employs a piezoceramic transducer array and the TDOAR for quantitative estimating the compactness of concrete infill in a CFFT.

  20. A Study on Load Carrying Capacity of Fly Ash Based Polymer Concrete Columns Strengthened Using Double Layer GFRP Wrapping

    Directory of Open Access Journals (Sweden)

    S. Nagan

    2014-01-01

    Full Text Available This paper investigates the suitability of glass fiber reinforced polymer (GFRP sheets in strengthening of fly ash based polymer members under compression. Experimental results revealed that load carrying capacity of the confined columns increases with GFRP sheets wrapping. Altogether 18 specimens of M30 and G30 grade short columns were fabricated. The G30 specimens were prepared separately in 8 molarity and 12 molarity of sodium hydroxide concentration. Twelve specimens for low calcium fly ash based reinforced polymer concrete and six specimens of ordinary Portland cement reinforced concrete were cast. Three specimens from each molarity fly ash based reinforced polymer concrete and ordinary Portland cement reinforced concrete were wrapped with double layer of GFRP sheets. The load carrying capacity of fly ash based polymer concrete was tested and compared with control specimens. The results show increase in load carrying capacity and ductility index for all strengthened elements. The maximum increase in load carrying capacity was 68.53% and is observed in strengthened G30 specimens.

  1. Comparison of the design rules for the end of the prestressed concrete double tee component between China and the United States

    Directory of Open Access Journals (Sweden)

    Meng Xian Hong

    2016-01-01

    Full Text Available Precast prestressed concrete double tee is an economic bearing component which can be made into a large span, large coverage area .From the angle of the design for the end of the precast prestressed concrete double tee component, flexure and axial tension in extended end, direct shear, diagonal tension at re-entrant corner, diagonal tension in extended end and the connection of the end of precast prestressed double tee component in China and the United States are compared. The comparative study provide the direction for the future development of China in the double tee,including strengthening the end reinforcement and increasing end connections.

  2. Double exchange model on triangular lattice: Non-coplanar spin configuration and phase transition near quarter filling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, G.P., E-mail: bugubird_zhang@hotmail.com [Department of Physics, Renmin University of China, Beijing 100872 (China); Zhang, Jian [3M Company, 3M Corporate Headquarters, 3M Center, St. Paul, MN 55144-1000 (United States); Zhang, Qi-Li [Data Center for High Energy Density Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Zhou, Jiang-Tao [College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060 (China); Shangguan, M.H. [Department of Physics, Renmin University of China, Beijing 100872 (China)

    2013-05-15

    Unconventional anomalous Hall effect in frustrated pyrochlore oxides is originated from spin chirality of non-coplanar localized spins, which can also be induced by the competition between ferromagnetic (FM) double exchange interaction J{sub H} and antiferromagnetic superexchange interaction J{sub AF}. Here truncated polynomial expansion method and Monte Carlo simulation are adopted to investigate the above model on two-dimensional triangular lattice. We discuss the influence of the range of FM-type spin–spin correlation and strong electron–spin correlation on the truncation error of spin–spin correlation near quarter filling. Two peaks of the probability distribution of spin–spin correlation in non-coplanar spin configuration clearly show that non-coplanar spin configuration is an intermediate phase between FM and 120° spin phase. Near quarter filling, there is a phase transition from FM into non-coplanar and further into 120° spin phase when J{sub AF} continually increases. Finally the effect of temperature on the magnetic structure is discussed.

  3. Determination of chlorine, sulfur and carbon in reinforced concrete structures by double-pulse laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Labutin, Timur A., E-mail: timurla@laser.chem.msu.ru [Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory 1-3, Moscow 119991 (Russian Federation); Popov, Andrey M.; Zaytsev, Sergey M.; Zorov, Nikita B. [Lomonosov Moscow State University, Department of Chemistry, Leninskie Gory 1-3, Moscow 119991 (Russian Federation); Belkov, Mikhail V.; Kiris, Vasilii V.; Raikov, Sergey N. [B.I. Stepanov Institute of Physics, Nezavisimosti Ave. 68, Minsk 220072 (Belarus)

    2014-09-01

    Accurate and reliable quantitative determination of non-metal corrosion agents in concrete is still an actual task of analytical use of LIBS. Two double-pulse LIBS systems were tested as a tool for the determination of chlorine, sulfur and carbon in concretes. Both systems had collinear configuration; a laboratory setup was equipped with an ICCD and two lasers (355/532 nm + 540 nm), but a CCD was a detector for a mobile system with one laser (1064 nm). Analytical lines of Cl I at 837.59 nm, S I at 921 nm and C I at 247.86 nm were used to plot calibration curves. Optimal interpulse delays for the laboratory setup were 4 μs for chlorine and 2.8 μs for carbon, while an interpulse delay of 2 μs was optimal for chlorine and sulfur determination with the mobile system. We suggested the normalization of the Cl I line at 837.59 nm to the Mg II line at 279.08 nm (visible at 837.23 nm in the third order) to compensate for pulse-to-pulse fluctuations of chlorine lines. It provided the decrease of the detection limit of chlorine from 400 ppm to 50 ppm. Therefore, we reported that LIBS can be used to determine main corrosive active substances under ambient conditions in concrete below critical threshold values. Moreover, the application of the mobile system for in-situ qualitative assessment of corrosion way of a steel cage of a swimming pool dome was also demonstrated. It was found that chloride corrosion due to the disinfection of water was the main way for corrosion of the open part steel and the steel rebar inside the concrete. - Highlights: • Determination of chlorine, sulfur and carbon in concrete in the air. • Comparison of mobile and laboratory LIBS systems. • LOD by double-pulse LIBS under ambient conditions: for sulfur 1500 ppm, for chlorine — 50 ppm. • Background level of carbon content in concrete is about 0.27% wt.

  4. Investigation on the fiber based approach to estimate the axial load carrying capacity of the circular concrete filled steel tube (CFST)

    Science.gov (United States)

    Piscesa, B.; Attard, M. M.; Suprobo, P.; Samani, A. K.

    2017-11-01

    External confining devices are often used to enhance the strength and ductility of reinforced concrete columns. Among the available external confining devices, steel tube is one of the most widely used in construction. However, steel tube has some drawbacks such as local buckling which needs to be considered when estimating the axial load carrying capacity of the concrete-filled-steel-tube (CFST) column. To tackle this problem in design, Eurocode 4 provided guidelines to estimate the effective yield strength of the steel tube material. To study the behavior of CFST column, in this paper, a non-linear analysis using a fiber-based approach was conducted. The use of the fiber-based approach allows the engineers to predict not only the axial load carrying capacity but also the complete load-deformation curve of the CFST columns for a known confining pressure. In the proposed fiber-based approach, an inverse analysis is used to estimate the constant confining pressure similar to design-oriented models. This paper also presents comparisons between the fiber-based approach model with the experimental results and the 3D non-linear finite element analysis.

  5. Determination of chlorine, sulfur and carbon in reinforced concrete structures by double-pulse laser-induced breakdown spectroscopy

    Science.gov (United States)

    Labutin, Timur A.; Popov, Andrey M.; Zaytsev, Sergey M.; Zorov, Nikita B.; Belkov, Mikhail V.; Kiris, Vasilii V.; Raikov, Sergey N.

    2014-09-01

    Accurate and reliable quantitative determination of non-metal corrosion agents in concrete is still an actual task of analytical use of LIBS. Two double-pulse LIBS systems were tested as a tool for the determination of chlorine, sulfur and carbon in concretes. Both systems had collinear configuration; a laboratory setup was equipped with an ICCD and two lasers (355/532 nm + 540 nm), but a CCD was a detector for a mobile system with one laser (1064 nm). Analytical lines of Cl I at 837.59 nm, S I at 921 nm and C I at 247.86 nm were used to plot calibration curves. Optimal interpulse delays for the laboratory setup were 4 μs for chlorine and 2.8 μs for carbon, while an interpulse delay of 2 μs was optimal for chlorine and sulfur determination with the mobile system. We suggested the normalization of the Cl I line at 837.59 nm to the Mg II line at 279.08 nm (visible at 837.23 nm in the third order) to compensate for pulse-to-pulse fluctuations of chlorine lines. It provided the decrease of the detection limit of chlorine from 400 ppm to 50 ppm. Therefore, we reported that LIBS can be used to determine main corrosive active substances under ambient conditions in concrete below critical threshold values. Moreover, the application of the mobile system for in-situ qualitative assessment of corrosion way of a steel cage of a swimming pool dome was also demonstrated. It was found that chloride corrosion due to the disinfection of water was the main way for corrosion of the open part steel and the steel rebar inside the concrete.

  6. Dynamic Response of a Long-Span Concrete-Filled Steel Tube Tied Arch Bridge and the Riding Comfort of Monorail Trains

    Directory of Open Access Journals (Sweden)

    Hongye Gou

    2018-04-01

    Full Text Available In this study, a dynamic response analysis procedure is proposed and applied to investigate the dynamic responses of a straddle-type concrete-filled steel tube tied arch bridge under train and truck loadings. A numerical model of the coupled monorail train–bridge system is established to investigate the dynamic behaviors of the bridge under moving trains. A refined three-dimensional finite element model is built for the bridge and a 15 degrees-of-freedom vehicle model is presented for the train. The numerical model is validated using in-situ test results and then used to analyze the dynamic displacement and acceleration of the bridge and the trains on the bridge. Based on the simulation results, the impact factor of the bridge is investigated and the riding comfort of the trains is evaluated. The investigation results show that the impact factor of vehicle loads reaches the maximum value when the resonance of the bridge is induced by the moving vehicles. The effect of train braking predominates the longitudinal vibration of the bridge but is negligible in the transverse and vertical directions. The vehicle speed is the dominating factor for the riding comfort of the train.

  7. Comportement des poteaux composites en profils creux en acier remplis de béton Behavior of composite columns in hollow steel section filled with concrete

    Directory of Open Access Journals (Sweden)

    Othmani N.

    2012-09-01

    Full Text Available Le but de cet article, est la determination des rigidites flexionnelles EIx et EIy d’fune section mixte acier beton et plus precisement d’fun poteau en tube d’facier de section rectangulaire, remplie de beton, sollicitee a la flexion bi-axiale (N, Mx et My. L’festimation des rigidites sera faite a partir d’fune approche theorique par une analyse du poteau en elements finis (element barre a 4 degres de liberte, basee sur les conditions d’fequilibres a mi-portee en utilisant la relation moment-courbure (M–Φ de l’felement deforme par application de l’fequation suivante: EI=M/Φ. Le comportement des materiaux est celui comme adopte par les reglements Eurocode 2 et 3, respectivement pour le beton et l’facier. Afin de valider l’fapproche theorique utilisee dans cette etude, deux comparaisons ont ete faites : une premiere permettant de comparer les resultats des rigidites determinees par les relations moments courbures et celles calculees par l’fEurocode 4 et une deuxieme comparaison entre les charges de ruines de deux poteaux de grandeurs natures avec ceux testes au laboratoire [2]. Au vu des resultats obtenus, nous pouvons conclure que l’approche théorique utilisée dans cette étude ainsi que les modèles de comportement des matériaux sont adéquats pour ce genre de problèmes. The purpose of this paper is the determination of flexural stiffness EIx and EIy of a concrete filled rectangular cross section of a composite steel column, under biaxial bending (N, Mx and My. The rigidities will be estimated from a theoretical approach using a finite element analysis (element bar with 4 degrees of freedom, based on the equilibrium conditions at mid-span using the moment-curvature relationships (M–Φ of the deformed element by applying the following equation: EI=M/Φ. The material behavior is the one adopted by Eurocode 2 and 3, respectively, for concrete and steel. To validate the theoretical approach used, two comparisons

  8. Effect of iron and carbonation on the diffusion of iodine and rhenium in waste encasement concrete and soil fill material under hydraulically unsaturated conditions

    International Nuclear Information System (INIS)

    Wellman, Dawn M.; Parker, Kent E.; Powers, Laura; Whyatt, Greg A.; Clayton, Libby N.; Mattigod, Shas V.; Wood, Marcus I.

    2008-01-01

    Assessing long-term performance of Category 3 cement wasteforms and accurate prediction for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e. sorption or precipitation). A set of sediment-concrete half-cell diffusion experiments was conducted under unsaturated conditions (4% and 7% by weight moisture content) using carbonated and non-carbonated concrete-soil half cells. Results indicate the behavior of Re and I release was comparable within a given half-cell test. Diffusivity in soil is a function of moisture content; a 3% increase in moisture content affords a one to two order of magnitude increase in diffusivity. Release of I and Re was 1-3 orders of magnitude less from non-carbonated, relative to carbonated, concrete monoliths. Inclusion of Fe in non-carbonate monoliths resulted in the lowest concrete diffusivity values for both I and Re. This suggests that in the presence of Fe, I and Re are converted to reduced species, which are less soluble and better retained within the concrete monolith. The release of I and Re was greatest from Fe-bearing, carbonated concrete monoliths, suggesting carbonation negates the effect of Fe on the retention of I and Re within concrete monoliths. This is likely due to enhanced formation of microcracks in the presence of Fe, which provide preferential paths for contaminant migration. Although the release of I and Re were greatest from carbonated concrete monoliths containing Fe, the migration of I and Re within a given half cell is dependent on the moisture content, soil diffusivity, and diffusing species

  9. [Therapeutic effect of double fill nine tastes soup in treating recurrent respiratory infection (RRI) and change of immune function in children].

    Science.gov (United States)

    Wang, Youcheng; Zhang, Lijuan; Hu, Guohua; Wang, Menghe; Tang, Xiaoyuan; Guo, Hui; Shi, Yimei; Chen, Shufang; Shi, Changchun

    2012-04-01

    To investigate the therapeutic effect of double fill nine tastes soup in treating children recurrent respiratory infection (RRTI) and the change of immune function. 77 RRTI patients were randomly selected into observation and control groups. The observation group was treated with Chinese medicine- double fill nine tastes soup,water frying points 2 times oral. The control was treated with transfer factor oral liquid,every 10 mL,2 times daily oral. Treatment periods were both two months. IgA, IgG, IgM and IL-12, TNF-alpha, INF-gamma were detected before and after treatment to assess the clinical effects and the changes of immune factors, meanwhile, a health group was established. Before treatment, compared with the health group, the serum IgA, IgG, IgM, IgE, IL-12, TNF-alpha, IFN-gamma in both groups were significantly different (P soup has significant effects in treating recurrent respiratory infection (RRI) and enhance the immune function in children.

  10. Subatmospheric double containment system

    International Nuclear Information System (INIS)

    Gans, D. Jr.; Noble, J.H.

    1978-01-01

    A reinforced concrete double wall nuclear containment structure with each wall including an essentially impervious membrane or liner and porous concrete filling the annulus between the two walls is described. The interior of the structure is maintained at subatmospheric pressure, and the annulus between the two walls is maintained at a subatmospheric pressure intermediate between that of the interior and the surrounding atmospheric pressure, during normal operation. In the event of an accident within the containment structure the interior pressure may exceed atmospheric pressure, but leakage from the interior to the annulus between the double walls will not result in the pressure of the annulus exceeding atmospheric pressure so that there is no net outleakage from the containment structure

  11. The impact of altering filling pressures in diagnostic outpatient hysteroscopy on the procedure completion rates and associated pain: a randomised double-blind controlled trial.

    Science.gov (United States)

    Haggag, Hisham M; Hassan, AbdelGany M A

    2016-02-01

    Several studies have compared different distension media and analgesics to optimise the efficiency of outpatient hysteroscopy. However, studies comparing different uterine filling pressures are scarce. The objective of this study was to evaluate and compare different uterine filling pressures during diagnostic outpatient hysteroscopy in an attempt to find the optimal pressure allowing adequate visualisation while minimising pain and increasing patient satisfaction. This was a double-blind randomised controlled trial. A total of 240 women who had diagnostic outpatient hysteroscopy were randomly divided into three equal groups: the uterine filling pressure was 30 mm Hg in group 1, 50 mm Hg in group 2 and 80 mm Hg in group 3. The primary outcome was adequate visualisation, and secondary outcomes were the proportion of completed procedures, pain perceived during the procedure, immediately after the procedure and 30 min later. Adequate visualisation was lower in group 1 (88.7% vs 97.5% and 98.7%; P = 0.009), but was not different between groups 2 and 3 (P > 0.999). The proportion of completed procedures was not different among the groups. There was a progressive increase in pain scores from the lower to the higher pressure groups during the procedure, immediately after the procedure and 30 min after completing the procedure. Uterine filling pressure of 50 mm Hg was associated with better visualisation than 30 mm Hg and lower pain scores than that of 80 mmHg with no difference in the proportion of completed procedures. © 2015 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

  12. Steel plates and concrete filled composite shear walls related nuclear structural engineering: Experimental study for out-of-plane cyclic loading

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaohu [The College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124 (China); Li, Xiaojun, E-mail: beerli@vip.sina.com [The College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124 (China); Institute of Geophysics, China Earthquake Administration, Beijing 100081 (China)

    2017-04-15

    Based on the program of CAP1400 nuclear structural engineering, the out-of-plane seismic behavior of steel plate and concrete infill composite shear walls (SCW) was investigated. 6 1/5 scaled specimens were conducted which consist of 5 SCW specimens and 1 reinforced concrete (RC) specimen. The specimens were tested under out-of-plane cyclic loading. The effect of the thickness of steel plate, vertical load and the strength grade of concrete on the out-of-plane seismic behavior of SCW were analyzed. The results show that the thickness of steel plate and vertical load have great influence on the ultimate bearing capacity and lateral stiffness, however, the influence of the strength grade of concrete was little within a certain range. SCW is presented to have a better ultimate capacity and lateral stiffness but have worse ductility in failure stage than that of RC. Based on the experiment, the cracking load of concrete infill SCW was analyzed in theory. The modified calculation formula of the cracking load was made, the calculated results showed good agreement with the test results. The formula can be used as the practical design for the design of cracking loads.

  13. Steel plates and concrete filled composite shear walls related nuclear structural engineering: Experimental study for out-of-plane cyclic loading

    International Nuclear Information System (INIS)

    Li, Xiaohu; Li, Xiaojun

    2017-01-01

    Based on the program of CAP1400 nuclear structural engineering, the out-of-plane seismic behavior of steel plate and concrete infill composite shear walls (SCW) was investigated. 6 1/5 scaled specimens were conducted which consist of 5 SCW specimens and 1 reinforced concrete (RC) specimen. The specimens were tested under out-of-plane cyclic loading. The effect of the thickness of steel plate, vertical load and the strength grade of concrete on the out-of-plane seismic behavior of SCW were analyzed. The results show that the thickness of steel plate and vertical load have great influence on the ultimate bearing capacity and lateral stiffness, however, the influence of the strength grade of concrete was little within a certain range. SCW is presented to have a better ultimate capacity and lateral stiffness but have worse ductility in failure stage than that of RC. Based on the experiment, the cracking load of concrete infill SCW was analyzed in theory. The modified calculation formula of the cracking load was made, the calculated results showed good agreement with the test results. The formula can be used as the practical design for the design of cracking loads.

  14. Evaluation of self-healing ability in protective coatings modified with combinations of layered double hydroxides and cerium molibdate nanocontainers filled with corrosion inhibitors

    International Nuclear Information System (INIS)

    Montemor, M.F.; Snihirova, D.V.; Taryba, M.G.; Lamaka, S.V.; Kartsonakis, I.A.; Balaskas, A.C.; Kordas, G.C.; Tedim, J.; Kuznetsova, A.; Zheludkevich, M.L.; Ferreira, M.G.S.

    2012-01-01

    Nowadays, there is a strong demand on the search of thinner, but more effective organic coatings for corrosion protection of metallic substrates, like galvanised steel, used in the automotive industry. In order to guarantee effective corrosion protection of these coatings, and because chromate-based pigments cannot be used, one of the most attractive strategies consists on the modification of the organic matrix with nano-additives filled with corrosion inhibitors, which can be released to the active sites. In this work, two different nano-additives are explored as potential self-healing materials for the development of active protective coatings. These additives are layered double hydroxides and cerium molybdate hollow nanospheres loaded with mercaptobenzothiazole, as a corrosion inhibitor. These additives were added to epoxy primers, individually, or combining the two nanoadditives in the same layer. The electrochemical behaviour and the potential of self-healing ability were studied by electrochemical impedance spectroscopy, scanning vibrating electrode technique and scanning ion-selective electrode technique. The results reveal that both types of nanocontainers can provide effective corrosion inhibition on artificial induced defects, at different stages of the degradation process. Moreover, the results also show that there is a synergistic effect concerning corrosion inhibition and self-healing potential when a mixture of the two nanocontainers is used. The mechanism of self healing is presented and discussed in terms of effect of organic inhibitor and role of the nanocontainers, including effect of cerium ions released from cerium molibdate nanoparticles.

  15. Self-Consolidating Concrete for Prestressed Bridge Girders : Research Brief

    Science.gov (United States)

    2017-08-01

    Self-consolidating concrete (SCC) is commonly used as an alternative to conventional concrete (CC) in precast, prestressed concrete (PSC) bridge girders. The high strength, highly workable mixture can flow through dense reinforcement to fill formwork...

  16. Anti-aging and filling efficacy of six types hyaluronic acid based dermo-cosmetic treatment: double blind, randomized clinical trial of efficacy and safety.

    Science.gov (United States)

    Nobile, Vincenzo; Buonocore, Daniela; Michelotti, Angela; Marzatico, Fulvio

    2014-12-01

    Human skin aging is a multifactorial and complex biological process affecting the different skin constituents. Even if the skin aging mechanism is not yet fully unravelled is evident that epidermis loses the principal molecule responsible for binding and retaining water molecules, resulting in loss of skin moisture and accounting for some of the most striking alterations of the aged skin. This Study investigated the cosmetic filling efficacy of Fillerina® in decreasing the skin aging signs and in improving facial volume deficiencies. A placebo-controlled, double-blind, randomized clinical trial was carried out on 40 healthy female subjects showing mild to moderate clinical signs of skin aging. The effect of the treatment on skin surface and on face volumes was assessed both in the short-term (3 h after a single product application) and in the long-term (7, 14, and 30 days after continuative daily use). Three hours after a single application and after 7, 14, and 30 days of treatment the lips volume was increased by 8.5%, 11.3%, 12.8%, and 14.2%. After 7, 14, and 30 days: (1) skin sagging of the face contours was decreased by -0.443 ± 0.286, -1.124 ± 0.511, and -1.326 ± 0.649 mm, respectively; (2) skin sagging of the cheekbones contours was decreased by -0.989 ± 0.585, -2.500 ± 0.929, and -2.517 ± 0.927 mm, respectively; (3) cheekbones volume was increased by 0.875 ± 0.519, 2.186 ± 0.781, and 2.275 ± 0.725 mm, respectively; (4) wrinkle volume was decreased by -11.3%, -18.4%, and -26.3%, respectively; and (5) wrinkle depth was decreased by -8.4%, -14.5%, and -21.8% respectively. This study demonstrated the positive filling effect of Fillerina® in decreasing the clinical signs of skin aging and in improving the face volumes. © 2014 Wiley Periodicals, Inc.

  17. How Concrete Is Concrete?

    Science.gov (United States)

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  18. Displacement response of a concrete arch dam to seasonal temperature fluctuations and reservoir level rise during the first filling period: evidence from geodetic data

    Directory of Open Access Journals (Sweden)

    Cemal Ozer Yigit

    2016-07-01

    Full Text Available The present study evaluates the dynamic behaviour of the Ermenek Dam, the second highest dam in Turkey, based on conventional geodetic measurements and Finite Element Model (FEM analyses during its first filling period. In total, eight periods of measured deformation are considered from the end of construction until the reservoir reached its full capacity. The displacement response of the dam to the reservoir level and to seasonal temperature variations is examined in detail. Time series of apparent total displacements at the middle of the crest of the dam exhibits periodicity and linear trends. Correlation analysis revealed that periodic and linear displacement responses of the dam are related to variations of seasonal temperature and linearly increased reservoir level, respectively, indicating a relation between temperature, water load and dam deformation. It is also concluded that measured deformations based on geodetic data show good agreement with the predicted deformation obtained by the FEM analysis.

  19. Spectral Induced Polarization of Low-pH Concrete. Influence of the Electrical Double Layer and Pore Size

    Science.gov (United States)

    Leroy, P. G.; Gaboreau, S.; Zimmermann, E.; Hoerdt, A.; Claret, F.; Huisman, J. A.; Tournassat, C.

    2017-12-01

    Low-pH concretes are foreseen to be used in nuclear waste disposal. Understanding their reactivity upon the considered host-rock is a key point. Evolution of mineralogy, porosity, pore size distribution and connectivity can be monitored in situ using geophysical methods such as induced polarization (IP). This electrical method consists of injecting an alternating current and measuring the resulting voltage in the porous medium. Spectral IP (SIP) measurements in the 10 mHz to 10 kHz frequency range were carried out on low-pH concrete and cement paste first in equilibrium and then in contact with a CO2 enriched and diluted water. We observed a very high resistivity of the materials (> 10 kOhm m) and a strong phase shift between injected current and measured voltage (superior to 40 mrad and above 100 mrad for frequencies > 100 Hz). These observations were modelled by considering membrane polarization with ion exclusion in nanopores whose surface electrical properties were computed using a basic Stern model of the cement/water interface. Pore size distribution was deduced from SIP and was compared to the measured ones. In addition, we observed a decrease of the material resistivity due to the dissolution of cement in contact with external water. Our results show that SIP may be a valuable method to monitor the mineralogy and the petrophysical and transport properties of cements.

  20. Experimental study of a foam concrete based on local Tunisian materials

    Directory of Open Access Journals (Sweden)

    Ellouze Dorra

    2018-01-01

    Full Text Available The building sector in Tunisia is very energy-intensive, the largest share of energy consumption comes from factories of building materials namely brick and cement plants. This work is part of the reduction of the energy bill in the building envelope. Indeed, the foam concrete can be walls in single or double wall with better insulating power. This paper presents an experimental study on the technical problems related to the formulation and manufacture of a new cellular concrete in Tunisia, called "foam" concrete, from Tunisian local materials. Indeed, six varieties of sand of different provenance and grain size will be analyzed, the "good" sand is the one that is best suited for the manufacture of foam concrete. Two clean, fine-grained (0/2mm rolled grain sands were retained. Then four foam concretes were formulated using each time a single type of sand and varying the density namely 0.8 and 1. These four formulations were tested mechanically and thermally. The results found showed that compressive strengths do not exceed 1.5 MPa at 28 days. Thus, the foam concrete can be used only as a filling concrete in non-load bearing elements such as partition walls. The guarded hot plate method was used to determine the thermal conductivities of the four foamed concretes studied. A low thermal conductivity was found of the order of 0.22 W/m°K which prove the insulating power of foam concrete.

  1. TRANSPARENT CONCRETE

    OpenAIRE

    Sandeep Sharma*, Dr. O.P. Reddy

    2017-01-01

    Transparent concrete is the new type of concrete introduced in todays world which carries special property of light transmitting due to presence of light Optical fibres. Which is also known as translucent concrete or light transmitting concrete, it is achieved by replacing coarse aggregates with transparent alternate materials (Optical fibres). The binding material in transparent concrete may be able to transmit light by using clear resins the concrete mix. The concrete used in industry in pr...

  2. Double containment shell for nuclear power plants

    International Nuclear Information System (INIS)

    Sykora, D.

    1977-01-01

    A double containment shell is proposed for nuclear power plants, especially those equipped with pressurized water reactors. The shell offers increased environmental protection from primary circuit accidents. The inner shell is built of steel or concrete while the outer shell is always built of concrete. The space between the two shells is filled with water and is provided with several manholes and with stiffeners designed for compensation for load due to the water hydrostatic pressure. Water serves the airtight separation of the containment shell inside from the environment and the absorption of heat released in a primary circuit accident. In case the inner shell is made of concrete, it is provided with heat-removal tubes in-built in its walls ensuring rapid heat transfer from the inside of the containment to the water in the interwall space. (Z.M.)

  3. Experimental study of columns partially filled with concrete under compressive axial loads Etude expérimentale des colonnes partiellement remplis par le béton sous charge axiale

    Directory of Open Access Journals (Sweden)

    Achoura D.

    2012-09-01

    Full Text Available Dans cette étude, on présente les résultats expérimentaux obtenus sur des poteaux mixtes béton-acier mince réalisés par soudures. Un total de 24 profilés en acier, et en forme de I a été testé sous charge de compression uni-axiale à l’âge de 28 jours. les spécimens ont été réparties comme suit: 4 à vides, 4 partiellement remplies avec un béton ordinaire sans l’addition des connecteurs, 4 renforcés par des connecteurs de cisaillements de type cornière en U, 4 autres l’ont été avec des connecteurs de cisaillements type goujons et 8 restants ont été renforcés avec des liens transversaux d’espacement 100mm, 50mm, soudés aux bouts des ailes opposées. Les principaux paramètres étudiés sont: l’élancement du profilé, le type de connecteur de renforcement. A partir des résultats d’essais obtenus, il est confirmé que les parois minces sont plus sensibles de l’apparition au voilement et la longueur des profilés a un effet considérable sur la capacité portante et le mode de rupture. L’addition des connecteurs de renforcement a confirmé l’augmentation de la charge ultime par rapport aux profilés sans connecteurs. In the present work, results of tests conducted on thin welded steel-concrete stubs are presented. A total of 24 stubs an I steel section were tested under axial compression at 28 days after the date of casting, 4 were empty, 4 filled with normal concrete, 8 columns had shear connecters welded along the centreline of the web, and 8 columns had steel rods welded between the tips of opposing flanges on both sides of the spacing of the transverse link 100 mm and 50 mm. The main parameters studied were: the heel height, and type of connector strengthening. From the test results, it is confirmed that the thin walls are more sensitive to the appearance local buckling and the length of the profiles has a significant effect on the bearing capacity and failure mode. The bearing capacity was increased

  4. How Concrete is Concrete

    OpenAIRE

    Koeno Gravemeijer

    2010-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two diff...

  5. How Concrete is Concrete

    Directory of Open Access Journals (Sweden)

    Koeno Gravemeijer

    2010-07-01

    Full Text Available If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two different ways of making things concrete. Next another role of manipulatives, will be discussed, namely that of means for scaffolding and communication. In this role, manipulatives may function as means of support in a process that aims at helping students to build on their own thinking while constructing more sophisticated mathematics

  6. Interfacial pH-gradient induced micro-capillary filling with the aid of transverse electrodes arrays in presence of electrical double layer effects

    International Nuclear Information System (INIS)

    Jain, Avi; Chakraborty, Suman

    2010-01-01

    In the present work, we outline the design and analysis of a micro-capillary filling mechanism through the aid of interfacial pH gradients (and hence interfacial tension gradients) generated by employing arrays of transverse electrodes inducing step changes in voltages, in a natural buffer system that requires low power and no synthetic ampholytes. The capillary transport is modulated by a dynamic and non-trivial coupling between the interfacial tension and viscous resistances, as a consequence of the underlying intermolecular interactions. The competing effects of the driving and the retarding forces effectively determine the displacement, velocity and acceleration characteristics of the capillary front, in a dynamically evolving manner. A comprehensive theoretical model of capillary dynamics is developed here to address these issues in details, thereby revealing the combined influence of the interfacial electrochemistry and the applied transverse voltages, as guided by the pertinent fundamental thermodynamic principles governed by free energy considerations and the physico-chemical phenomena over interfacial scales. Non-trivial implications of the pH-gradient driven micro-capillary transport are aptly emphasized, so as to offer significant physical insights on the adopted strategy as a guiding principle for facilitating capillary filling processes by inducing a modulation in the effective interfacial energy. Particular implications on the capillary filling time are also pinpointed, revealing the effectiveness of the adopted design strategy. Finally, a universal scaling relationship of the capillary filling time as a function of the pertinent operating parameters is derived, so as to provide a generalized guideline for implementing the design scheme. A non-dimensional parameter, depending simultaneously on the inter-electrode pitch and the transverse voltage, is identified, which may be kept to a minimal limit within the other operating constraints of the chosen

  7. How Concrete is Concrete?

    Directory of Open Access Journals (Sweden)

    Koeno Gravemeijer

    2011-01-01

    Full Text Available If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two different ways of making things concrete. Next another role of manipulatives, will be discussed, namely that of means for scaffolding and communication. In this role, manipulatives may function as means of support in a process that aims at helping students to build on their own thinking while constructing more sophisticated mathematics.Key words:  Conceret Learning Materials, School Math, Common Sense, Scaffolding, Communication DOI: http://dx.doi.org/10.22342/jme.2.1.780.1-14

  8. Pervious Concrete

    OpenAIRE

    Torsvik, Øyvind André Hoff

    2012-01-01

    Pervious concrete is a material with a high degree of permeability but generally low strength. The material is primarily used for paving applications but has shown promise in many other areas of usage. This thesis investigates the properties of pervious concrete using normal Norwegian aggregates and practices. An overview of important factors when it comes to designing and producing pervious concrete is the result of this investigation. Several experiments have been performed in the concrete ...

  9. Elliptical As2Se3 filled core ultra-high-nonlinearity and polarization-maintaining photonic crystal fiber with double hexagonal lattice cladding

    Science.gov (United States)

    Li, Feng; He, Menghui; Zhang, Xuedian; Chang, Min; Wu, Zhizheng; Liu, Zheng; Chen, Hua

    2018-05-01

    A high birefringence and ultra-high nonlinearity photonic crystal fiber (PCF) is proposed, which is composed of an elliptical As2Se3-doped core and an inner cladding with hexagonal lattice. Optical properties of the PCF are simulated by the full-vector finite element method. The simulation results show that the high birefringence of ∼0.33, ultra-high-nonlinearity coefficient of 300757 W-1km-1 and the low confinement loss can be achieved in the proposed PCF simultaneously at the wavelength of 1.55 μm. Furthermore, by comparison with the other two materials (80PbO•20Ga2O3, As2S3) filled in the core, the As2Se3-doped PCF is found to have the highest birefringence and nonlinearity due to its higher refractive index and nonlinear refractive index. The flattened dispersion feature, as well as the low confinement loss of the proposed PCF structure make it suitable as a wide range of applications, such as the coherent optical communications, polarization-maintaining and nonlinear optics, etc.

  10. Half-metallic and insulating natures in Ru-based ordered double perovskite oxides Ba_2X"I"I"IRu"VO_6 (X = V, Cr) induced by 3d-t_2_g"n orbital filling

    International Nuclear Information System (INIS)

    Saad, H.-E.M. Musa; Althoyaib, S.S.

    2017-01-01

    In this paper, we present results of a comprehensive systemic study of the crystal, electronic and magnetic structures on two members of Ru-based ordered double perovskite oxides Ba_2XRuO_6 (X = V, Cr). For the corporate compound, the analysis of density of states (DOS) results suggests that the 3d-t_2_g orbital filling plays a major role in governing the conduction mechanism in these systems. The DOS and magnetic results show that Ba_2XRuO_6 exhibits half-metallic (HM) nature as X = V, where the electronic structure of Ba_2V"I"I"IRu"VO_6 with 3d-t_2_g"2 behaves like that of HM ferrimagnetic (FI), switches to compensate FI insulating behavior as X = Cr, with an extra electron filled 3d-t_2_g"3 in Ba_2Cr"I"I"IRu"VO_6. We find, on consideration of electron correlation (LSDA+U) and spin-orbital coupling (SOC) effects that the electronic structure of Ba_2XRuO_6 takes a HM nature, whereas it is completely transformed to insulating nature once an extra electron filled the 3d-t_2_g orbitals in X = Cr case. Such tuning is accompanied by spin-state hopping of one electron from half-filled spin-state in Ru"V (t_2_g"3 e_g"0) to two and three occupied spin-state in V"I"I"I (t_2_g"2 e_g"0) and Cr"I"I"I (t_2_g"3 e_g"0), respectively. The charge distribution results show that this extra electron occupies chiefly the spin-down of conduction orbitals and plays a major role in determining the electronic and magnetic structures of Ba_2XRuO_6 system. - Highlights: • Half-metallic and insulating natures are observed in Ba_2XRuO_6 (X = V, Cr). • 3d-t_2_g"n orbitals filling plays a major role in governing the conduction mechanism. • LSDA+U method under density functional theory (DFT) is considered. • HM ferrimagnetic (FI) (X = V) switch to compensate FI insulating (X = Cr).

  11. Structural Precast Concrete Handbook

    DEFF Research Database (Denmark)

    Kjærbye, Per Oluf H

    Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly.......Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly....

  12. Water Entrainment in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

    This report gives a survey of different techniques for incorporation of designed, water-filled cavities in concrete: Water entrainment. Also an estimate of the optimum size of the water inclusions is given. Water entrainment can be used to avoid self-desiccation and self-desiccation shrinkage...... during hydration [1,26]. What is needed is some sort of container which retains the shape of the water when mixed into the concrete. The container may function based on several different physical or chemical principles. Cells and gels are examples of containers found in nature. A cell membrane provides...... a boundary to water, whereas a polymer network incorporates water in its intersticious space with its affinity due to interaction energy and polymer entropy. Such containers allow water to be stored as an entity. In relation to concrete the water encapsulation may be accomplished either before or after start...

  13. Study of technological features of tubular compressed concrete members in concreting

    Directory of Open Access Journals (Sweden)

    Voskobiinyk Olena

    2017-01-01

    Full Text Available The technological features of core concreting were analyzed as the main factor in ensuring of strength and reliability of compressed concrete-filled steel tubular (CFST members. We have conducted the analysis of existing concreting methods of CFST members. In this respect, the most dangerous types of possible technological defects of concrete core of CFST members are inhomogeneity along the height, voids, caverns, and concrete “weak spots”. The authors considered the influence of such technological factors of concreting: placeability, time, concrete mixture compaction method, concreting height on the concrete core strength of CFST members. Based on the experimental studies conducted we suggested the regression correlations for determining the concrete strength of CFST members of different length depending on the movability of concrete mixture and a time for its compaction. The authors performed the correlation analysis of technological factors of concreting on the strength of the concrete core. We carried out the comparison of data on the concrete core strength of CFST members, that were determined by non-destructive methods (sclerometer test results, ultrasonic method and direct compression strength tests. We experimentally proved that using movable mixtures with the slump of about 4 – 9 cm the overall variation coefficient of concrete core strength of CFST members along the height reaches nearly 13%. Based on the experimental studies conducted we suggested the guidelines on optimal regimes of concrete compaction during manufacturing CFST members at a construction site environment.

  14. Glazed Concrete

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

    Why glazed concrete? Concrete hardens and finds its strength at room temperature whereas clay products must first be fired before they achieve this strength. They are stronger and three times as durable as clay products, which is a weighty reason for choosing concrete.5 Another reason, which....... If this succeeds, it will be possible to manufacture thin, large-scale glazed concrete panels comparable in size to concrete sandwich construction and larger which, with or without back-casting, can work as load-bearing construction elements....

  15. Concrete Hinges

    DEFF Research Database (Denmark)

    Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

    2014-01-01

    In the first part of the 20th century concrete hinges developed by Freyssinet and Mesnager were widely tested and implemented in concrete structures. The concrete hinges were used a great deal in closed-spandrel arch bridges. Since such a bridge type has not been competitive for the past 40 years......, the research in concrete hinges has not evolved significantly in that period. But introducing a new state-of-the-art concrete arch bridge solution (Pearl-Chain arches invented at the Technical University of Denmark) creates a necessity of a concrete hinge research based on modern standards. Back when research...... in concrete hinges was more common different designs were proposed for the geometry and reinforcement. Previous research focused on fatigue, multi-axial stresses around the hinge throat, and the relation between rotation- and moment. But many different test-setups were proposed by different researchers...

  16. Concrete structures

    CERN Document Server

    Setareh, Mehdi

    2017-01-01

    This revised, fully updated second edition covers the analysis, design, and construction of reinforced concrete structures from a real-world perspective. It examines different reinforced concrete elements such as slabs, beams, columns, foundations, basement and retaining walls and pre-stressed concrete incorporating the most up-to-date edition of the American Concrete Institute Code (ACI 318-14) requirements for the design of concrete structures. It includes a chapter on metric system in reinforced concrete design and construction. A new chapter on the design of formworks has been added which is of great value to students in the construction engineering programs along with practicing engineers and architects. This second edition also includes a new appendix with color images illustrating various concrete construction practices, and well-designed buildings. The ACI 318-14 constitutes the most extensive reorganization of the code in the past 40 years. References to the various sections of the ACI 318-14 are pro...

  17. Concrete Fibrations

    OpenAIRE

    Pagnan, Ruggero

    2017-01-01

    As far as we know, no notion of concrete fibration is available. We provide one such notion in adherence to the foundational attitude that characterizes the adoption of the fibrational perspective in approaching fundamental subjects in category theory and discuss it in connection with the notion of concrete category and the notions of locally small and small fibrations. We also discuss the appropriateness of our notion of concrete fibration for fibrations of small maps, which is relevant to a...

  18. NANOMODIFIED CONCRETE

    Directory of Open Access Journals (Sweden)

    B. M. Khroustalev

    2015-01-01

    Full Text Available One of the main directions in construction material science is the development of  next generation concrete that is ultra-dense, high-strength, ultra-porous, high heat efficient, extra corrosion-resistant. Selection of such direction is caused by extreme operational impacts on the concrete, namely: continuously increasing load on the concrete and various dynamics of such loads; the necessity in operation of concrete products in a wide temperature range and their exposure to various chemical and physical effects.The next generation concrete represents high-tech concrete mixtures with additives that takes on and retain the required properties when hardening and being used under any operational conditions. A differential characteristic of the next generation concrete is its complexity that presumes usage of various mineral dispersed components, two- and three fractional fine and coarse aggregates, complex chemical additives, combinations of polymer and iron reinforcement.Design strength and performance properties level of the next generation concrete is achieved by high-quality selection of the composition, proper selection of manufacturing techniques, concrete curing, bringing the quality of concrete items to the required level of technical condition during the operational phase. However, directed formation of its structure is necessary in order to obtain high-tech concrete.Along with the traditional methods for regulation of the next generation concrete structure, modification of concrete while using silica nanoparticles is also considered as a perspective one because the concrete patterning occurs due to introduction of a binder in a mineral matrix. Due to this it is possible to obtain nano-modified materials with completely new properties.The main problem with the creation of nano-modified concrete is a uniform distribution of nano-materials in the volume of the cement matrix which is particularly important in the cases of adding a modifier in

  19. Effectiveness of Horizontal Rebar on Concrete Block Retaining Wall Strength

    OpenAIRE

    Krishpersad Manohar; Rikhi Ramkissoon

    2016-01-01

    The effectiveness of including a horizontal rebar compared to only a vertical rebar in concrete filled core interlocking concrete block retaining wall sections was investigated with respect to the horizontal retaining force. Experimental results for three specimens of interlocking blocks with vertical rebar and concrete filled cores showed an average horizontal retaining force of 24546 N ± 5.7% at an average wall deflection of 13.3 mm. Experimental results for three wall specimens of interloc...

  20. Lattice modeling of aggregate interlocking in concrete

    DEFF Research Database (Denmark)

    Eliáš, Jan; Stang, Henrik

    2012-01-01

    roughness, i.e.what is termed aggregate interlocking. We demonstrate this enhancement via the simulation of mixed-mode experiments on concrete performed at a laboratory at the Technical University of Denmark. Double notched concrete specimens were initially pre-cracked in tension. Then, various combinations...

  1. About Dental Amalgam Fillings

    Science.gov (United States)

    ... and Medical Procedures Dental Devices Dental Amalgam About Dental Amalgam Fillings Share Tweet Linkedin Pin it More ... should I have my fillings removed? What is dental amalgam? Dental amalgam is a dental filling material ...

  2. Concrete domains

    OpenAIRE

    Kahn, G.; Plotkin, G.D.

    1993-01-01

    This paper introduces the theory of a particular kind of computation domains called concrete domains. The purpose of this theory is to find a satisfactory framework for the notions of coroutine computation and sequentiality of evaluation.

  3. Benign gastric filling defect

    International Nuclear Information System (INIS)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y.

    1979-01-01

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  4. Benign gastric filling defect

    Energy Technology Data Exchange (ETDEWEB)

    Oh, K. K.; Lee, Y. H.; Cho, O. K.; Park, C. Y. [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  5. Benign gastric filling defect

    Energy Technology Data Exchange (ETDEWEB)

    Oh, K K; Lee, Y H; Cho, O K; Park, C Y [Yonsei University College of Medicine, Seoul (Korea, Republic of)

    1979-06-15

    The gastric lesion is a common source of complaints to Orientals, however, evaluation of gastric symptoms and laboratory examination offer little specific aid in the diagnosis of gastric diseases. Thus roentgenography of gastrointestinal tract is one of the most reliable method for detail diagnosis. On double contract study of stomach, gastric filling defect is mostly caused by malignant gastric cancer, however, other benign lesions can cause similar pictures which can be successfully treated by surgery. 66 cases of benign causes of gastric filling defect were analyzed at this point of view, which was verified pathologically by endoscope or surgery during recent 7 years in Yensei University College of Medicine, Severance Hospital. The characteristic radiological picture of each disease was discussed for precise radiologic diagnosis. 1. Of total 66 cases, there were 52 cases of benign gastric tumor 10 cases of gastric varices, 5 cases of gastric bezoar, 5 cases of corrosive gastritis, 3 cases of granulomatous disease and one case of gastric hematoma. 2. The most frequent causes of benign tumors were adenomatous polyp (35/42) and the next was leiomyoma (4/42). Others were one of case of carcinoid, neurofibroma and cyst. 3. Characteristic of benign adenomatous polyp were relatively small in size, smooth surface and were observed that large size, benign polyp was frequently type IV lesion with a stalk. 4. Submucosal tumors such as leiomyoma needed differential diagnosis with polypoid malignant cancer. However, the characteristic points of differentiation was well circumscribed smooth margined filling defect without definite mucosal destruction on surface. 5. Gastric varices showed multiple lobulated filling defected especially on gastric fundus that changed its size and shape by respiration and posture of patients. Same varices lesions on esophagus and history of liver disease were helpful for easier diagnosis. 6. Gastric bezoar showed well defined movable mass

  6. Photocatalyticpaving concrete

    OpenAIRE

    Lyapidevskaya Ol'ga Borisovna; Fraynt Mikhail Aleksandrovich

    2014-01-01

    Today bituminous concrete is a conventional paving material. Among its advantages one can name dustlessness and noiselessness, fine wear (up to 1 mm a year) and fine maintainability. As the main disadvantages of this material one can name high slipperiness under humidification, low durability and weather resistance. Besides that, during placement of the bituminous concrete a lot of different air pollutants are emitted, which are harmful for environment and human’s health (they are listed in t...

  7. Photocatalyticpaving concrete

    Directory of Open Access Journals (Sweden)

    Lyapidevskaya Ol'ga Borisovna

    2014-02-01

    Full Text Available Today bituminous concrete is a conventional paving material. Among its advantages one can name dustlessness and noiselessness, fine wear (up to 1 mm a year and fine maintainability. As the main disadvantages of this material one can name high slipperiness under humidification, low durability and weather resistance. Besides that, during placement of the bituminous concrete a lot of different air pollutants are emitted, which are harmful for environment and human’s health (they are listed in the paper according to the US Environmental Protection Agency materials. As an alternative, one can use cement-concrete pavement, which is in many ways more efficient than the bituminous concrete. It is proposed to enhance environmental performance of the cement-concrete pavement via usage of photocatalysis. The mechanism of different photocatalytic reactions is described in the paper, namely heterogeneous and homogeneous photocatalysis, photo-induces, photoactivated catalysis and catalytical photoreactions. It is pro-posed to use heterogeneous photocatalysis with titanium dioxide as a photocatalyst. The mechanism of photo oxidation of air contaminants, with the usage of titanium dioxide is2described. The paper sets problems, connected with the sensibilization of TiOto thevisible light (it is proposed to use titanium dioxide, doped with the atoms of certain elements to increase its sensibility to the visible light and with the development of a new photocatalytic paving concrete, which will meet the requirements, specified for paving in the climatic and traffic conditions of the Russian Federation.

  8. Self-Placing Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Certain concrete pours have areas where the congestion of reinforcing bars make placement of concrete almost impossible. Using conventional placing and vibration techniques, the resulting concrete can have considerable honeycombing due to the development of voids. Self-placing concrete is a possible solution to the problem. Also known as self-compactable concrete, self-consolidating concrete, flowable concrete, and non-vibration concrete. These concretes eliminate the need for vibration in a ...

  9. Flow conditions of fresh mortar and concrete in different pipes

    International Nuclear Information System (INIS)

    Jacobsen, Stefan; Haugan, Lars; Hammer, Tor Arne; Kalogiannidis, Evangelos

    2009-01-01

    The variation in fresh concrete flow rate over the pipe cross section was investigated on differently coloured and highly flowable concrete mixes flowing through pipes of different materials (rubber, steel, acryl). First, uncoloured (gray) concrete was poured through the pipe and the pipe blocked. Similar but coloured (black) concrete was then poured into the pipe filled with gray concrete, flowing after the gray concrete for a while before being blocked and hardened. The advance of the colouring along the pipe wall (showing boundary flow rate) was observed on the moulded concrete surface appearing after removing the pipe from the hardened concrete. The shapes of the interfaces between uncoloured and coloured concrete (showing variation of flow rate over the pipe cross section) were observed on sawn surfaces of concrete half cylinders cut along the length axes of the concrete-filled pipe. Flow profiles over the pipe cross section were clearly seen with maximum flow rates near the centre of the pipe and low flow rate at the pipe wall (typically rubber pipe with reference concrete without silica fume and/or stabilizers). More plug-shaped profiles, with long slip layers and less variation of flow rate over the cross section, were also seen (typically in smooth acrylic pipes). Flow rate, amount of concrete sticking to the wall after flow and SEM-images of pipe surface roughness were observed, illustrating the problem of testing full scale pumping.

  10. Concrete durability

    OpenAIRE

    Gaspar Tébar, Demetrio

    1991-01-01

    The evidence that the concrete is not a material for ever was noticed from the beginning of its industrial use. In the present work, the author describes the studies carried out during the last century and the early ages of the present one, mainly devoted to the study of the durability in sea water. At the present days, and in spite of the numerous papers published from then, the study of the concrete durability continues focusing the research priorities and economical resources of rese...

  11. Historic Concrete : From Concrete Repair to Concrete Conservation

    NARCIS (Netherlands)

    Heinemann, H.A.

    2013-01-01

    Concrete like materials were already applied during the Roman Empire. After the decline of the Roman Empire, a wide scale application of concrete only reappeared in the 19th century. Here lies also the origin of modern (reinforced) concrete. Since then, both concrete application and composition have

  12. Experimental investigation of photocatalytic effects of concrete in air purification adopting entire concrete waste reuse model.

    Science.gov (United States)

    Xu, Yidong; Chen, Wei; Jin, Ruoyu; Shen, Jiansheng; Smallbone, Kirsty; Yan, Chunyang; Hu, Lei

    2018-07-05

    This research investigated the capacities of recycled aggregate concrete adopting entire concrete waste reuse model in degrading NO 2. Two major issues within environmental sustainability were addressed: concrete waste reuse rate and mitigation of hazards substances in the polluted air. The study consisted of two stages: identification of proper replacement rates of recycled concrete wastes in new concrete mixture design, and the evaluation of photocatalytic performance of recycled aggregate concrete in degrading NO 2 . It was found that replacement rates up to 3%, 30%, and 50% for recycled power, recycled fine aggregate, and recycled coarse aggregate respectively could be applied in concrete mixture design without deteriorating concrete strength. Recycled aggregates contained both positive attributes ("internal curing") and negative effects (e.g., lower hardness) to concrete properties. It was found that 30%-50% of natural coarse aggregate replaced by recycled coarse aggregates coated with TiO 2 would significantly improve the photocatalytic performance of concrete measured by degradation rate of NO 2 . Micro-structures of recycled aggregates observed under microscope indicated that soaking recycled aggregates in TiO 2 solution resulted in whiskers that filled the porosity within recycled aggregates which enhanced concrete strength. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Bond behavior of self compacting concrete

    Directory of Open Access Journals (Sweden)

    Ponmalar S.

    2018-03-01

    Full Text Available The success of an optimum design lies in the effective load transfer done by the bond forces at the steel-concrete interface. Self Compacting Concrete, is a new innovative concrete capable of filling intrinsic reinforcement and gets compacted by itself, without the need of external mechanical vibration. For this reason, it is replacing the conventional vibrated concrete in the construction industry. The present paper outlays the materials and methods adopted for attaining the self compacting concrete and describes about the bond behavior of this concrete. The bond stress-slip curve is similar in the bottom bars for both SCC and normal concrete whereas a higher bond stress and stiffness is experienced in the top and middle bars, for SCC compared to normal concrete. Also the interfacial properties revealed that the elastic modulus and micro-strength of interfacial transition zone [ITZ] were better on the both top and bottom side of horizontal steel bar in the SCC mixes than in normal vibrated concrete. The local bond strength of top bars for SCC is about 20% less than that for NC. For the bottom bars, however, the results were almost the same.

  14. Bond behavior of self compacting concrete

    Science.gov (United States)

    Ponmalar, S.

    2018-03-01

    The success of an optimum design lies in the effective load transfer done by the bond forces at the steel-concrete interface. Self Compacting Concrete, is a new innovative concrete capable of filling intrinsic reinforcement and gets compacted by itself, without the need of external mechanical vibration. For this reason, it is replacing the conventional vibrated concrete in the construction industry. The present paper outlays the materials and methods adopted for attaining the self compacting concrete and describes about the bond behavior of this concrete. The bond stress-slip curve is similar in the bottom bars for both SCC and normal concrete whereas a higher bond stress and stiffness is experienced in the top and middle bars, for SCC compared to normal concrete. Also the interfacial properties revealed that the elastic modulus and micro-strength of interfacial transition zone [ITZ] were better on the both top and bottom side of horizontal steel bar in the SCC mixes than in normal vibrated concrete. The local bond strength of top bars for SCC is about 20% less than that for NC. For the bottom bars, however, the results were almost the same.

  15. High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Traian Oneţ

    2009-01-01

    Full Text Available The paper presents the last studies and researches accomplished in Cluj-Napoca related to high performance concrete, high strength concrete and self compacting concrete. The purpose of this paper is to raid upon the advantages and inconveniences when a particular concrete type is used. Two concrete recipes are presented, namely for the concrete used in rigid pavement for roads and another one for self-compacting concrete.

  16. Sodium fill of FFTF

    International Nuclear Information System (INIS)

    Waldo, J.B.; Greenwell, R.K.; Keasling, T.A.; Collins, J.R.; Klos, D.B.

    1980-02-01

    With construction of the Fast Flux Test Facility (FFTF) completed, the first major objective in the startup program was to fill the sodium systems. A sodium fill sequence was developed to match construction completion, and as systems became available, they were inerted, preheated, and filled with sodium. The secondary sodium systems were filled first while dry refueling system testing was in progress in the reactor vessel. The reactor vessel and the primary loops were filled last. This paper describes the methods used and some of the key results achieved for this major FFTF objective

  17. Concrete spirituality

    OpenAIRE

    Kritzinger, Johannes N.J.

    2014-01-01

    This article reflects on a number of liturgical innovations in the worship of Melodi ya Tshwane, an inner-city congregation of the Uniting Reformed Church in Southern Africa (URCSA). The focus of the innovations was to implement the understanding of justice in Article 4 of the Confession of Belhar, a confessional standard of the URCSA. The basic contention of the article is that well designed liturgies that facilitate experiences of beauty can nurture a concrete spirituality to mobilise urba...

  18. A Blocking Criterion for Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm; Stang, Henrik; Geiker, Mette Rica

    2005-01-01

    To benefit from the full potential of Self-Compacting Concrete (SCC) prediction tools for the form filling ability of SCC are needed. This paper presents a theoretical concept for assessment of the blocking resistance of SCC. A critical concrete flow rate above which no blocking occurs...... is introduced. The critical flow rate takes into account the mix design, the rheological properties of the matrix and concrete, and the geometry of the flow domain....

  19. EXPERIMENTAL STUDY ON HYBRID FIBER SELF COMPACTING CONCRETE

    OpenAIRE

    S. M. Leela Bharathi

    2017-01-01

    Self-Compacting Concrete is a recently developed concept in which the ingredients of the concrete mix are proportioned in such a way that it can flow under its own weight to completely fill the formwork and passes through the congested reinforcement without segregation and self-consolidate without any mechanical vibration. Several studies in the past have revealed the usefulness of fibres to improve the structural properties of concrete like ductility, post crack resistance, energy absorption...

  20. Containers, particularly prestressed concrete pressure vessels for nuclear reactor plants

    International Nuclear Information System (INIS)

    Schoening, J.; Schwiers, H.G.; Mitterbacher, P.

    1986-01-01

    Pressure and temperature changes act on the liner, which cause differential expansion between the liner and the prestressed concrete. So that there will be no overload or damage to the liner, its anchoring or the concrete structure, cutouts are provided in the concrete at deflection positions of the steel cladding, connections and penetrations. These cut-outs are filled with inserts made of elastic or plastic material. (DG) [de

  1. Phase 2 microwave concrete decontamination results

    International Nuclear Information System (INIS)

    White, T.L.; Foster, D. Jr.; Wilson, C.T.; Schaich, C.R.

    1995-01-01

    The authors report on the results of the second phase of a four-phase program at Oak Ridge National Laboratory to develop a system to decontaminate concrete using microwave energy. The microwave energy is directed at the concrete surface through the use of an optimized wave guide antenna, or applicator, and this energy rapidly heats the free water present in the interstitial spaces of the concrete matrix. The resulting steam pressure causes the surface to burst in much the same way popcorn pops in a home microwave oven. Each steam explosion removes several square centimeters of concrete surface that are collected by a highly integrated wave guide and vacuum system. The authors call this process the microwave concrete decontamination, or MCD, process. In the first phase of the program the principle of microwaves concrete removal concrete surfaces was demonstrated. In these experiments, concrete slabs were placed on a translator and moved beneath a stationary microwave system. The second phase demonstrated the ability to mobilize the technology to remove the surfaces from concrete floors. Area and volume concrete removal rates of 10.4 cm 2 /s and 4.9 cm 3 /S, respectively, at 18 GHz were demonstrated. These rates are more than double those obtained in Phase 1 of the program. Deeper contamination can be removed by using a longer residence time under the applicator to create multiple explosions in the same area or by taking multiple passes over previously removed areas. Both techniques have been successfully demonstrated. Small test sections of painted and oil-soaked concrete have also been removed in a single pass. Concrete with embedded metal anchors on the surface has also been removed, although with some increased variability of removal depth. Microwave leakage should not pose any operational hazard to personnel, since the observed leakage was much less than the regulatory standard

  2. Refractory concretes

    International Nuclear Information System (INIS)

    Holcombe, C.E. Jr.

    1979-01-01

    Novel concrete compositions comprise particles of aggregate material embedded in a cement matrix, said cement matrix produced by contacting an oxide selected from the group of Y 2 O 3 , La 2 O 3 , Nd 2 O 3 , Sm 2 O 3 , Eu 2 O 3 and Gd 2 O 3 with an aqueous solution of a salt selected from the group of NH 4 HO 3 , NH 4 Cl, YCl 3 and Mg(NO 3 ) 2 to form a fluid mixture; and allowing the fluid mixture to harden

  3. Concrete construction engineering handbook

    CERN Document Server

    Nawy, Edward G

    2008-01-01

    Provides coverage of concrete construction engineering and technology. This work features discussions focusing on: the advances in engineered concrete materials; reinforced concrete construction; specialized construction techniques; and, design recommendations for high performance.

  4. Recycled concrete aggregate in portland cement concrete.

    Science.gov (United States)

    2013-01-01

    Aggregates can be produced by crushing hydraulic cement concrete and are known as recycled concrete : aggregates (RCA). This report provides results from a New Jersey Department of Transportation study to identify : barriers to the use of RCA in new ...

  5. Optimizing of the recycling of contaminated concrete debris. Final report

    International Nuclear Information System (INIS)

    Kloeckner, J.; Rasch, H.; Schloesser, K.H.; Schon, T.

    1999-01-01

    1. Latest research: So far concrete debris from nuclear facilities has been free released or was treated as radioactive waste. 2. Objective: The objective of this study is to develop solutions and methods for recycling concrete debris. The amount of materials used in nuclear facilities should be limited and the contamination of new materials should be avoided. 3. Methods: The status of recycling was presented using examples of operating or completed decommissioning as well as available studies and literature. The quality requirements for the production of new concrete products using recycled materials has been discussed. The expected amounts of concrete debris for the next 12 years was estimated. For the proposed recycling examples, radiological and economic aspects have been considered. 4. Results: The production of qualified concrete products from concrete debris is possible by using modified receptions. Technical regulations to this are missing. There is no need for the utilization of large amounts of concrete debris for shielding walls. For the production of new shielding-containers for radioactive waste, concrete debris can be applied. Regarding the distance to a central recycling facility the use of mobile equipment can be economical. By using the concrete for filling the cavity or space in a final storage, it is possible to dispose the whole radioactive debris. 5. Application possibilities: The use of concrete debris as an inner concrete shielding in waste-containers today is already possible. For the manufacture of qualified concrete products by using recycling products, further developments and regulations are necessary. (orig.) [de

  6. The Future Concrete: Self-Compacting Concrete

    Directory of Open Access Journals (Sweden)

    Liana Iureş

    2010-01-01

    Full Text Available The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

  7. The Future Concrete: Self-Compacting Concrete

    OpenAIRE

    Iureş, Liana; Bob, Corneliu

    2010-01-01

    The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

  8. Concrete durability

    Directory of Open Access Journals (Sweden)

    Gaspar Tébar, Demetrio

    1991-03-01

    Full Text Available The evidence that the concrete is not a material for ever was noticed from the beginning of its industrial use. In the present work, the author describes the studies carried out during the last century and the early ages of the present one, mainly devoted to the study of the durability in sea water. At the present days, and in spite of the numerous papers published from then, the study of the concrete durability continues focusing the research priorities and economical resources of researchers and industries related with this material. Moreover, the new laboratory techniques are allowing to understand old problems and even to open again the discussion on reaction mechanisms which were believed to be completely understood. The article finalizes with a brief description of the numerous studies carried out at the Institute Eduardo Torroja on concrete durability, mainly those related with the resistance against gypsum attack (so abundant in our country land and against sea water attack.

    La realidad de que el hormigón no es un material eterno y es susceptible de sufrir ataques por agentes químicos, fue constatada desde el comienzo mismo de su uso industrial. En el presente trabajo el autor enumera los estudios realizados el siglo pasado y a comienzos del presente sobre la durabilidad del hormigón en agua de mar. En la actualidad y a pesar de los numerosos trabajos desarrollados desde entonces, el estudio de la durabilidad del hormigón sigue centrando la atención prioritaria y los recursos económicos de los investigadores e industrias relacionadas con este material. Además las nuevas técnicas de estudio están permitiendo comprender antiguos problemas e incluso reabrir la discusión sobre mecanismos de reacción que se creían completamente explicados. Finaliza el artículo con una descripción somera de los múltiples trabajos realizados en el Instituto Eduardo Torreja sobre la materia, en especial los estudios realizados sobre

  9. Concrete Memories

    DEFF Research Database (Denmark)

    Wiegand, Frauke Katharina

    2015-01-01

    This article traces the presence of Atlantikwall bunkers in amateur holiday snapshots and discusses the ambiguous role of the bunker site in visual cultural memory. Departing from my family’s private photo collection from twenty years of vacationing at the Danish West coast, the different mundane...... and poetic appropriations and inscriptions of the bunker site are depicted. Ranging between overlooked side presences and an overwhelming visibility, the concrete remains of fascist war architecture are involved in and motivate different sensuous experiences and mnemonic appropriations. The article meets...... the bunkers’ changing visuality and the cultural topography they both actively transform and are being transformed by through juxtaposing different acts and objects of memory over time and in different visual articulations....

  10. Processing and discarding method for contaminated concrete wastes

    International Nuclear Information System (INIS)

    Yamamoto, Kazuo; Konishi, Masao; Matsuda, Atsuo; Iwamoto, Yoshiaki; Yoshikane, Toru; Koie, Toshio; Nakajima, Yoshiro

    1998-01-01

    Contaminated concrete wastes are crashed into granular concrete wastes having a successive grain size distribution. They are filled in a contamination processing vessel and made hardenable in the presence of a water-hardenable material in the granular concrete wastes. When underground water intrudes into the contamination processing vessel filled with the granular concrete wastes upon long-term storage, the underground water reacts with the water-hardenable material to be used for the solidification effect. Accordingly, leaching of contaminated materials due to intrusion of underground water can be suppressed. Since the concrete wastes have a successive grain size distribution, coarse grains can be used as coarse aggregates, medium grains can be used as fine aggregates and fine grains can be used as a solidifying material. Accordingly, the amount of wastes after processing can be remarkably reduced, with no supply of a solidifying material from outside. (T.M.)

  11. Development of recycling techniques on decommissioning concrete waste

    International Nuclear Information System (INIS)

    Ishikura, Takeshi; Oguri, Daiichiro; Sukekiyo, Mitsuaki

    2000-01-01

    Nuclear Power Engineering Corporation (NUPEC) has been developing decommissioning techniques, implemented under a contract with the Ministry of International Trade and Industry (MITI), to verify and improve the performance of the key decommissioning techniques. One of main themes is on concrete recycling techniques, which deals with high quality aggregate retrieval from concrete waste, high efficient usage of the by-product powder to recycling products, and effective usage of radioactive concrete to filling material for waste form. This paper describes progress and accomplishment on the concrete recycling technique development which started in 1996. (author)

  12. Shear transfer in concrete reinforced with carbon fibers

    Science.gov (United States)

    El-Mokadem, Khaled Mounir

    2001-10-01

    Scope and method of study. The research started with preliminary tests and studies on the behavior and effect of carbon fibers in different water solutions and mortar/concrete mixes. The research work investigated the use of CF in the production of concrete pipes and prestressed concrete double-tee sections. The research then focused on studying the effect of using carbon fibers on the direct shear transfer of sand-lightweight reinforced concrete push-off specimens. Findings and conclusions. In general, adding carbon fibers to concrete improved its tensile characteristics but decreased its compressive strength. The decrease in compressive strength was due to the decrease in concrete density as fibers act as three-dimensional mesh that entrapped air. The decrease in compressive strength was also due to the increase in the total surface area of non-cementitious material in the concrete. Sand-lightweight reinforced concrete push-off specimens with carbon fibers had lower shear carrying capacity than those without carbon fibers for the same cement content in the concrete. Current building codes and specifications estimate the shear strength of concrete as a ratio of the compressive strength. If applying the same principals then the ratio of shear strength to compressive strength for concrete reinforced with carbon fibers is higher than that for concrete without carbon fibers.

  13. Self-Compacting Concrete

    OpenAIRE

    Okamura, Hajime; Ouchi, Masahiro

    2003-01-01

    Self-compacting concrete was first developed in 1988 to achieve durable concrete structures. Since then, various investigations have been carried out and this type of concrete has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mix-design method and self-compactability testing methods have been carried out from the viewpoint of making self-compacting concrete a standard concrete.

  14. Filling a Conical Cavity

    Science.gov (United States)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  15. Hypothesis of Lithocoding: Origin of the Genetic Code as a "Double Jigsaw Puzzle" of Nucleobase-Containing Molecules and Amino Acids Assembled by Sequential Filling of Apatite Mineral Cellules.

    Science.gov (United States)

    Skoblikow, Nikolai E; Zimin, Andrei A

    2016-05-01

    The hypothesis of direct coding, assuming the direct contact of pairs of coding molecules with amino acid side chains in hollow unit cells (cellules) of a regular crystal-structure mineral is proposed. The coding nucleobase-containing molecules in each cellule (named "lithocodon") partially shield each other; the remaining free space determines the stereochemical character of the filling side chain. Apatite-group minerals are considered as the most preferable for this type of coding (named "lithocoding"). A scheme of the cellule with certain stereometric parameters, providing for the isomeric selection of contacting molecules is proposed. We modelled the filling of cellules with molecules involved in direct coding, with the possibility of coding by their single combination for a group of stereochemically similar amino acids. The regular ordered arrangement of cellules enables the polymerization of amino acids and nucleobase-containing molecules in the same direction (named "lithotranslation") preventing the shift of coding. A table of the presumed "LithoCode" (possible and optimal lithocodon assignments for abiogenically synthesized α-amino acids involved in lithocoding and lithotranslation) is proposed. The magmatic nature of the mineral, abiogenic synthesis of organic molecules and polymerization events are considered within the framework of the proposed "volcanic scenario".

  16. Concrete spent fuel storage casks dose rates

    International Nuclear Information System (INIS)

    Bace, M.; Jecmenica, R.; Trontl, K.

    1998-01-01

    Our intention was to model a series of concrete storage casks based on TranStor system storage cask VSC-24, and calculate the dose rates at the surface of the casks as a function of extended burnup and a prolonged cooling time. All of the modeled casks have been filled with the original multi-assembly sealed basket. The thickness of the concrete shield has been varied. A series of dose rate calculations for different burnup and cooling time values have been performed. The results of the calculations show rather conservative original design of the VSC-24 system, considering only the dose rate values, and appropriate design considering heat rejection.(author)

  17. Fibre Concrete 2017

    Science.gov (United States)

    2017-09-01

    9th international conference on fibre reinforced concretes (FRC), textile reinforced concretes (TRC) and ultra-high performance concretes (UHPC) Preface The Fibre Concrete Conference series is held biennially to provide a platform to share knowledge on fibre reinforced concretes, textile concretes and ultra-high performance concretes regarding material properties and behaviour, technology procedures, topics of long-term behaviour, creep, durability; sustainable aspects of concrete including utilisation of waste materials in concrete production and recycling of concrete. The tradition of Fibre Concrete Conferences started in eighties of the last century. Nowadays the conference is organized by the Department of Concrete and Masonry Structures of the Czech Technical University in Prague, Faculty of Civil Engineering. The 9th International Conference Fibre Concrete 2017 had 109 participants from 27 countries all over the world. 55 papers were presented including keynote lectures of Professor Bažant, Professor Bartoš and Dr. Broukalová. The conference program covered wide range of topics from scientific research to practical applications. The presented contributions related to performance and behaviour of cement based composites, their long-term behaviour and durability, sustainable aspects, advanced analyses of structures from these composites and successful applications. This conference was organized also to honour Professor Zděnek P. Bažant on the occasion of his jubilee and to appreciate his merits and discoveries in the field of fibre reinforced composites, structural mechanics and engineering.

  18. Physical and mechanical properties of self-compacting concrete containing superplasticizer and metakaolin

    Science.gov (United States)

    Shahidan, Shahiron; Tayeh, Bassam A.; Jamaludin, A. A.; Bahari, N. A. A. S.; Mohd, S. S.; Zuki Ali, N.; Khalid, F. S.

    2017-11-01

    The development of concrete technology shows a variety of admixtures in concrete to produce special concrete. This includes the production of self-compacting concrete which is able to fill up all spaces, take formwork shapes and pass through congested reinforcement bars without vibrating or needing any external energy. In this study, the main objective is to compare the physical and mechanical properties of self-compacting concrete containing metakaolin with normal concrete. Four types of samples were produced to study the effect of metakaolin towards the physical and mechanical properties of self-compacting concrete where 0%, 5%, 10% and 15% of metakaolin were used as cement replacement. The physical properties were investigated using slump test for normal concrete and slump flow test for self-compacting concrete. The mechanical properties were tested for compressive strength and tensile strength. The findings of this study show that the inclusion of metakaolin as cement replacement can increase both compressive and tensile strength compared to normal concrete. The highest compressive strength was found in self-compacting concrete with 15% metakaolin replacement at 53.3 MPa while self-compacting concrete with 10% metakaolin replacement showed the highest tensile strength at 3.6 MPa. On top of that, the finishing or concrete surface of both cube and cylinder samples made of self-compacting concrete produced a smooth surface with the appearance of less honeycombs compared to normal concrete.

  19. Control de la tenacidad de los hormigones reforzados con fibras usando el ensayo de doble punzonamiento (ensayo barcelona Quality control of fiber reinforced concretes by mean of double punshing test (barcelona test

    Directory of Open Access Journals (Sweden)

    Sergio Carmona Malatesta

    2009-08-01

    Full Text Available Tradicionalmente, se utiliza el ensayo de vigas prismáticas sometidas a flexión para caracterizar la resistencia y el comportamiento en el régimen post fisuración del hormigón reforzado con fibras (HRF. Sin embargo, estos ensayos presentan una alta dispersión en sus resultados cuestionando su empleo para el control sistemático del HRF en obras; tienen, además el inconveniente de tratarse de ensayos complejos que requieren de probetas pesadas y de personal de laboratorio altamente calificado. Alternativamente, se ha propuesto el uso de otros ensayos normalizados de tracción directa e indirecta para realizar la caracterización de propiedades de los HRF, pero éstos han resultado ser muy complejos de ejecutar, sin obtener grandes mejoras en relación a la alta dispersión de los resultados. Con la finalidad de solucionar esta serie de inconvenientes, se ha propuesto el uso de un ensayo de tracción indirecta basado en una configuración del ensayo de doble punzonamiento, al que se ha denominado "Ensayo Barcelona". Este ensayo requiere de probetas de pequeñas dimensiones, con una alta superficie específica de fractura, permitiendo obtener valores representativos de la resistencia y de la tenacidad del material, con un coeficiente de variación de los resultados inferior al 13%, valor que es considerablemente menor a los alcanzados con otras metodologías experimentales. En este artículo se presentan los resultados de diferentes campañas experimentales, que permiten validar el uso del ensayo Barcelona como una metodología experimental adecuada para la sistemática caracterización del HRF en obras.Traditionally, flexural testing of prismatic beams is used to characterize the strength and behavior in post - cracking regime of fiber - reinforced concretes (FRC. These tests exhibit a high dispersion in their results, and therefore invalidate the use of such tests for the systematic control of FRCs works. Also, they have the disadvantage

  20. Tension-filled Governance?

    DEFF Research Database (Denmark)

    Celik, Tim Holst

    on the statesituated tension-filled functional relationship between legitimation and accumulation, the study both historically and theoretically reworks this approach and reapplies it for the post-1970s/1990s governance period. It asks whether and to what extent governance has served as a distinctive post- 1970s/1990s...

  1. filled neutron detectors

    Indian Academy of Sciences (India)

    Boron trifluoride (BF3) proportional counters are used as detectors for thermal neutrons. They are characterized by high neutron sensitivity and good gamma discriminating properties. Most practical BF3 counters are filled with pure boron trifluoride gas enriched up to 96% 10B. But BF3 is not an ideal proportional counter ...

  2. Gas filled detectors

    International Nuclear Information System (INIS)

    Stephan, C.

    1993-01-01

    The main types of gas filled nuclear detectors: ionization chambers, proportional counters, parallel-plate avalanche counters (PPAC) and microstrip detectors are described. New devices are shown. A description of the processes involved in such detectors is also given. (K.A.) 123 refs.; 25 figs.; 3 tabs

  3. Sustainable Concrete Technology

    Directory of Open Access Journals (Sweden)

    Sim J.

    2015-12-01

    Full Text Available The growing concern over global warming and significant ecological changes requires sustainable development in all fields of science and technology. Concrete not only consumes huge amount of energy and natural sources, but also emits large amount of CO2, mainly due to the production of cement. It is evident that such large amount of concrete production has put significant impact on the energy, resource, environment, and ecology of the society. Hence, how to develop the concrete technology in a sustainable way has become a significant issue. In this paper, some of Korean researches for sustainable development of concrete are presented. These are sustainable strengthening for deteriorated concrete structure, sustainable reinforcement of new concrete structure, sustainable concrete using recycled aggregate and supplementary cementing materials and finally application of each technique to precast concrete.

  4. Concrete pavement joint deterioration.

    Science.gov (United States)

    2015-12-01

    Concrete pavements are an important part of our national infrastructure. In recent years the relatively small number of reported joints deteriorating prematurely in concrete pavements around Indiana has increased. Changes over the past 45 years in IN...

  5. Concrete aggregate durability study.

    Science.gov (United States)

    2009-06-01

    There are many factors that affect the durability of Portland cement concrete (PCC), including the mix design and the : materials used, the quality of construction, and the environment. Durability is not an intrinsic property of the concrete, but : i...

  6. Half-metallic and insulating natures in Ru-based ordered double perovskite oxides Ba{sub 2}X{sup III}Ru{sup V}O{sub 6} (X = V, Cr) induced by 3d-t{sub 2g}{sup n} orbital filling

    Energy Technology Data Exchange (ETDEWEB)

    Saad, H.-E.M. Musa, E-mail: musa.1964@gmail.com; Althoyaib, S.S.

    2017-04-01

    In this paper, we present results of a comprehensive systemic study of the crystal, electronic and magnetic structures on two members of Ru-based ordered double perovskite oxides Ba{sub 2}XRuO{sub 6} (X = V, Cr). For the corporate compound, the analysis of density of states (DOS) results suggests that the 3d-t{sub 2g} orbital filling plays a major role in governing the conduction mechanism in these systems. The DOS and magnetic results show that Ba{sub 2}XRuO{sub 6} exhibits half-metallic (HM) nature as X = V, where the electronic structure of Ba{sub 2}V{sup III}Ru{sup V}O{sub 6} with 3d-t{sub 2g}{sup 2} behaves like that of HM ferrimagnetic (FI), switches to compensate FI insulating behavior as X = Cr, with an extra electron filled 3d-t{sub 2g}{sup 3} in Ba{sub 2}Cr{sup III}Ru{sup V}O{sub 6}. We find, on consideration of electron correlation (LSDA+U) and spin-orbital coupling (SOC) effects that the electronic structure of Ba{sub 2}XRuO{sub 6} takes a HM nature, whereas it is completely transformed to insulating nature once an extra electron filled the 3d-t{sub 2g} orbitals in X = Cr case. Such tuning is accompanied by spin-state hopping of one electron from half-filled spin-state in Ru{sup V} (t{sub 2g}{sup 3} e{sub g}{sup 0}) to two and three occupied spin-state in V{sup III} (t{sub 2g}{sup 2} e{sub g}{sup 0}) and Cr{sup III} (t{sub 2g}{sup 3} e{sub g}{sup 0}), respectively. The charge distribution results show that this extra electron occupies chiefly the spin-down of conduction orbitals and plays a major role in determining the electronic and magnetic structures of Ba{sub 2}XRuO{sub 6} system. - Highlights: • Half-metallic and insulating natures are observed in Ba{sub 2}XRuO{sub 6} (X = V, Cr). • 3d-t{sub 2g}{sup n} orbitals filling plays a major role in governing the conduction mechanism. • LSDA+U method under density functional theory (DFT) is considered. • HM ferrimagnetic (FI) (X = V) switch to compensate FI insulating (X = Cr).

  7. Lunar concrete for construction

    Science.gov (United States)

    Cullingford, Hatice S.; Keller, M. Dean

    1988-01-01

    Feasibility of using concrete for lunar-base construction has been discussed recently without relevant data for the effects of vacuum on concrete. Experimental studies performed earlier at Los Alamos have shown that concrete is stable in vacuum with no deterioration of its quality as measured by the compressive strength. Various considerations of using concrete successfully on the moon are provided in this paper along with specific conclusions from the existing data base.

  8. Reinforced sulphur concrete

    NARCIS (Netherlands)

    2014-01-01

    Reinforced sulphur concrete wherein one or more metal reinforcing members are in contact with sulphur concrete is disclosed. The reinforced sulphur concrete comprises an adhesion promoter that enhances the interaction between the sulphur and the one or more metal reinforcing members.

  9. Deterioration of Concrete Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Chloride ingress is a common cause of deterioration of reinforced concrete bridges. Concrete may be exposed to chloride by seawater or de-icing salts. The chloride initiates corrosion of the reinforcement, which through expansion disrupts the concrete. In addition, the corrosion reduces the cross...

  10. concrete5 for developers

    CERN Document Server

    Uzayr, Sufyan bin

    2014-01-01

    Whether you have had some previous experience with concrete5 or are entirely new to it, this book will help you understand all that you need to know in order to get started with concrete5 development. A background in PHP is required; some knowledge of HTML/CSS is needed in order to fully grasp the concepts underlying concrete5 theme development.

  11. Systolic ventricular filling.

    Science.gov (United States)

    Torrent-Guasp, Francisco; Kocica, Mladen J; Corno, Antonio; Komeda, Masashi; Cox, James; Flotats, A; Ballester-Rodes, Manel; Carreras-Costa, Francesc

    2004-03-01

    The evidence of the ventricular myocardial band (VMB) has revealed unavoidable coherence and mutual coupling of form and function in the ventricular myocardium, making it possible to understand the principles governing electrical, mechanical and energetical events within the human heart. From the earliest Erasistratus' observations, principal mechanisms responsible for the ventricular filling have still remained obscured. Contemporary experimental and clinical investigations unequivocally support the attitude that only powerful suction force, developed by the normal ventricles, would be able to produce an efficient filling of the ventricular cavities. The true origin and the precise time frame for generating such force are still controversial. Elastic recoil and muscular contraction were the most commonly mentioned, but yet, still not clearly explained mechanisms involved in the ventricular suction. Classical concepts about timing of successive mechanical events during the cardiac cycle, also do not offer understandable insight into the mechanism of the ventricular filling. The net result is the current state of insufficient knowledge of systolic and particularly diastolic function of normal and diseased heart. Here we summarize experimental evidence and theoretical backgrounds, which could be useful in understanding the phenomenon of the ventricular filling. Anatomy of the VMB, and recent proofs for its segmental electrical and mechanical activation, undoubtedly indicates that ventricular filling is the consequence of an active muscular contraction. Contraction of the ascendent segment of the VMB, with simultaneous shortening and rectifying of its fibers, produces the paradoxical increase of the ventricular volume and lengthening of its long axis. Specific spatial arrangement of the ascendent segment fibers, their interaction with adjacent descendent segment fibers, elastic elements and intra-cavitary blood volume (hemoskeleton), explain the physical principles

  12. A new technology for air-entrainment of concrete

    DEFF Research Database (Denmark)

    Laustsen, Sara; Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2008-01-01

    This paper describes a new technology for air-entrainment of concrete. The technology is based on the addition of dry superabsorbent polymers (SAP) to the concrete. A large amount of small internal water reservoirs are formed during mixing when SAP absorbs water and swells. The internal water......-entrainment include stability of the air void system and improved control of both the amount of added air and the air void size. The new technology based on SAP has been tested in freeze-thaw experiments, where the amount of surface scaling was measured. The results clearly show that SAP is beneficial for frost...... reservoirs are distributed throughout the concrete. During the hydration process the cement paste imbibes water from the water-filled SAP voids. Thereby the water-filled SAP voids turn into partly air-filled voids. The advantages of the SAP-based technology compared to traditional chemical air...

  13. Transport Through Cracked Concrete: Literature Review

    International Nuclear Information System (INIS)

    Langton, C.

    2012-01-01

    Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

  14. TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C.

    2012-05-11

    Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

  15. Modified pavement cement concrete

    Science.gov (United States)

    Botsman, L. N.; Ageeva, M. S.; Botsman, A. N.; Shapovalov, S. M.

    2018-03-01

    The paper suggests design principles of pavement cement concrete, which covers optimization of compositions and structures at the stage of mixture components selection due to the use of plasticizing agents and air-retaining substances that increase the viability of a concrete mixture. It also demonstrates advisability of using plasticizing agents together with air-retaining substances when developing pavement concrete compositions, which provides for the improvement of physical and mechanical properties of concrete and the reduction of cement binding agent consumption thus preserving strength indicators. The paper shows dependences of the main physical-mechanical parameters of concrete on cement consumption, a type and amount of additives.

  16. Material properties characterization - concrete

    International Nuclear Information System (INIS)

    England, G.L.; MacLeod, J.S.

    1978-01-01

    A review is presented of the six contributions in the SMiRT 4 conference to Session H5 on structural analysis of prestressed concrete reactor pressure vessels. These relate to short term stress-strain aspects of concrete loaded beyond the linear range in uniaxial and biaxial stress fields, to some time and temperature dependent properties of concrete at working stress levels, and to a programme of strain-gauge testing for the assessment of concrete properties. From the information discussed, it is clear that there are difficulties in determining material properties for concrete, and these are summarised. (UK)

  17. Autogenous Deformation of Concrete

    DEFF Research Database (Denmark)

    Autogenous deformation of concrete can be defined as the free deformation of sealed concrete at a constant temperature. A number of observed problems with early age cracking of high-performance concretes can be attributed to this phenomenon. During the last 10 years , this has led to an increased...... focus on autogenous deformation both within concrete practice and concrete research. Since 1996 the interest has been significant enough to hold international, yearly conferences entirely devoted to this subject. The papers in this publication were presented at two consecutive half-day sessions...... at the American Concrete Institute’s Fall Convention in Phoenix, Arizona, October 29, 2002. All papers have been reviewed according to ACI rules. This publication, as well as the sessions, was sponsored by ACI committee 236, Material Science of Concrete. The 12 presentations from 8 different countries indicate...

  18. 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...

  19. Preplaced aggregate concrete application on Fort St. Vrain PCRV construction

    International Nuclear Information System (INIS)

    Ople, F.S. Jr.

    1976-01-01

    Two distinct concreting methods were employed in the construction of the prestressed concrete reactor vessel (PCRV) of the Fort St. Vrain (FSV) Nuclear Generating Station, a 330 MW(e) High Temperature Gas-Cooled Reactor installation near Denver, Colorado. Preplaced aggregate concrete (PAC) techniques were employed in the PCRV bottom head and the core support floor; conventional job-mixed concrete was used in the PCRV sidewall and top head regions. This paper describes the successful application of PAC techniques utilized primarily in solving construction difficulties associated with confined and heavily congested regions of the PCRV. The PAC technique consists of placing coarse aggregate inside the forms, followed by injection of grout under pressure through embedded pipes to fill the interstices in the aggregate mass. Details of the PAC construction method including grout mix development, grouting equipment, grout pipe layout, grouting sequence, grout level monitoring, concrete temperature control, and pre-construction mockups are described. (author)

  20. Self-Compacting Concrete in Precast Elements Industry

    Directory of Open Access Journals (Sweden)

    Corneliu Bob

    2005-01-01

    Full Text Available In this paper the authors present information about the Self-Compacting Concrete and experimental results regarding the use of them into precast element industry. This type of concrete does not require vibration for placing and compaction; it is able to flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement. The experimental programme has take into account two prestressed beams which were prefabricated and tested on a special stands. The beams of Self-Compacting Concrete with the length of 24 m were prepared at „Beton-Star” Kft, Kecsekenet, Hungary, and used at the CASCO, Satu-Mare.

  1. Measurement of neutron diffusion length in heavy concrete

    International Nuclear Information System (INIS)

    Krejci, D.

    2007-04-01

    Using an aluminium sampler filled with heavy concrete the neutron diffusion length was determined, measuring thermal and fast neutrons over the whole beam hole with various threshold detectors using gold samples. These calculations should describe the neutron distribution in the whole concrete shield of the reactor and contribute to the investigation of the activation of the concrete shield using reactor parameters like operating time, power and neutron flux. Instrumentation, activation and positioning of the samples in the beam hole of the TRIGA Mark II reactor are described. (nevyjel)

  2. Experimental investigations on steel-concrete composite columns for varying parameters

    Science.gov (United States)

    Aparna, V.; Vivek, D.; Neelima, Kancharla; Karthikeyan, B.

    2017-07-01

    In this study, the experimental investigations on steel tubes filled with different types of concrete are presented. Steel tubes filled with fibre reinforced concrete using lathe waste and steel tube with concerned confined with steel mesh were investigated. The combinations were compared with steel tubes with conventional concrete. A total of 4 concrete filled steel tube (CFST) combinations were made with tubes of diameter 100 mm with wall thickness 1.6 mm and a height of 300 mm. Axial compression test to examine the resisting capacity of the columns and push-out test for noting the bond strength were performed. Coupon tests were also conducted to determine the mechanical properties of steel. The structural behaviour of the composite columns was evaluated from on the test results. It was observed that steel tube filled fibre reinforced possessed better bond strength and resistance to axial load.

  3. Dye filled security seal

    International Nuclear Information System (INIS)

    Wilson, D.C.

    1982-01-01

    A security seal for providing an indication of unauthorized access to a sealed object includes an elongate member to be entwined in the object such that access is denied unless the member is removed. The elongate member has a hollow, pressurizable chamber extending throughout its length that is filled with a permanent dye under greater than atmospheric pressure. Attempts to cut the member and weld it together are revealed when dye flows through a rupture in the chamber wall and stains the outside surface of the member

  4. Concrete laying laboratory

    International Nuclear Information System (INIS)

    Bastlova, K.

    1986-01-01

    The task of the concrete laying laboratory established within a special department for quality control and assurance at the Dukovany nuclear power plant, is to check the composition of concrete mixes produced by the central concrete production plant on the site, and the shipment, laying and processing of concrete. The composition is given of special barite and serpentinite concretes designed for biological shields. The system of checks and of filing the results is briefly described. Esperience is summed up from the operation of the concrete laying laboratory, and conclusions are formulated which should be observed on similar large construction sites. They include the precise definition of the designer's requirements for the quality of concrete, the surface finish of concrete surfaces, the method of concreting specific structures around bushings, increased density reinforcements and various technological elements, and requirements for shipment to poorly accessible or remote places. As for the equipment of the laboratory, it should be completed with an instrument for the analysis of fresh concrete mixes, a large capacity drying kiln, etc. (Z.M.)

  5. Special protective concretes

    International Nuclear Information System (INIS)

    Bouniol, P.

    2001-01-01

    Concrete is the most convenient material when large-scale radiation protection is needed. Thus, special concretes for nuclear purposes are used in various facilities like reactors, reprocessing centers, storage sites, accelerators, hospitals with nuclear medicine equipment, food ionization centers etc.. The recent advances made in civil engineering for the improvement of concrete durability and compactness are for a large part transposable to protection concretes. This article presents the basic knowledge about protection concretes with the associated typological and technological aspects. A large part is devoted to the intrinsic properties of concretes and to their behaviour in irradiation and temperature conditions: 1 - definition and field of application of special protective concretes; 2 - evolution of concepts and technologies (durability of structures, techniques of formulation, new additives, market evolution); 3 - design of protective structures (preliminary study, radiation characteristics, thermal constraints, damping and dimensioning, mechanical criteria); 4 - formulation of special concretes (general principles, granulates, hydraulic binders, pulverulent additives, water/cement ratio, reference composition of some special concretes); 5 - properties of special concretes (damping and thermo-mechanical properties); 6 - induced-irradiation and temperature phenomena (activation, radiolysis, mineralogical transformations, drying, shrinking, creep, corrosion of reinforcement). (J.S.)

  6. Double Tracks closure report

    International Nuclear Information System (INIS)

    1997-06-01

    This report describes the remediation activities performed and the results of postremediation radiation surveys conducted at the Double Tracks site, located on Range 71 North, of the Nellis Air Force Range (NAFR) in southern Nevada. This remediation was conducted from June to August 1996 in accordance with the Interim Corrective Action Plan (ICAP) to remediate the site to an acceptable risk to human health and the environment. Soil with a total transuranic activity greater than 200 picoCuries per gram (pCi/g) was excavated, shipped to the Nevada Test Site (NTS), and disposed at the Area 3 Radioactive Waste Management Site (RWMS). A total of 52.3 grams of plutonium (Pu) with an activity of 5.12 Curies was disposed. The concrete pad at ground zero (GZ) was broken up, placed in a Sealand reg-sign container, and shipped to the NTS Area 6 decontamination pad. Additionally, approximately 10 m 3 (350 ft 3 ) of soil containing small chips of concrete was shipped to the NTS Area 6 decontamination pad. The concrete and soil/concrete mixture will be further characterized prior to disposal. At the time this report was written, characterization samples were being collected, with analytical results expected in January 1997. It is anticipated that the material will be disposed in mid-1997. This remediation is an interim action because final cleanup levels have not been established

  7. Hydrogen Filling Station

    Energy Technology Data Exchange (ETDEWEB)

    Boehm, Robert F; Sabacky, Bruce; Anderson II, Everett B; Haberman, David; Al-Hassin, Mowafak; He, Xiaoming; Morriseau, Brian

    2010-02-24

    future. Project partners also conducted a workshop on hydrogen safety and permitting. This provided an opportunity for the various permitting agencies and end users to gather to share experiences and knowledge. As a result of this workshop, the permitting process for the hydrogen filling station on the Las Vegas Valley Water District’s land was done more efficiently and those who would be responsible for the operation were better educated on the safety and reliability of hydrogen production and storage. The lessons learned in permitting the filling station and conducting this workshop provided a basis for future hydrogen projects in the region. Continuing efforts to increase the working pressure of electrolysis and efficiency have been pursued. Research was also performed on improving the cost, efficiency and durability of Proton Exchange Membrane (PEM) hydrogen technology. Research elements focused upon PEM membranes, electrodes/catalysts, membrane-electrode assemblies, seals, bipolar plates, utilization of renewable power, reliability issues, scale, and advanced conversion topics. Additionally, direct solar-to-hydrogen conversion research to demonstrate stable and efficient photoelectrochemistry (PEC) hydrogen production systems based on a number of optional concepts was performed. Candidate PEC concepts included technical obstacles such as inefficient photocatalysis, inadequate photocurrent due to non-optimal material band gap energies, rapid electron-hole recombination, reduced hole mobility and diminished operational lifetimes of surface materials exposed to electrolytes. Project Objective 1: Design, build, operate hydrogen filling station Project Objective 2: Perform research and development for utilizing solar technologies on the hydrogen filling station and convert two utility vehicles for use by the station operators Project Objective 3: Increase capacity of hydrogen filling station; add additional vehicle; conduct safety workshop; develop a roadmap for

  8. Effect of lung deflation with indacaterol plus glycopyrronium on ventricular filling in patients with hyperinflation and COPD (CLAIM): a double-blind, randomised, crossover, placebo-controlled, single-centre trial.

    Science.gov (United States)

    Hohlfeld, Jens M; Vogel-Claussen, Jens; Biller, Heike; Berliner, Dominik; Berschneider, Korbinian; Tillmann, Hanns-Christian; Hiltl, Simone; Bauersachs, Johann; Welte, Tobias

    2018-02-21

    Pulmonary hyperinflation in chronic obstructive pulmonary disease (COPD) is associated with reduced biventricular end-diastolic volumes and increased morbidity and mortality. The combination of a long-acting β agonist (LABA) and a muscarinic antagonist (LAMA) is more effective in reducing hyperinflation than LABA-inhaled corticosteroid combination therapy but whether dual bronchodilation improves cardiac function is unknown. We did a double-blind, randomised, two-period crossover, placebo-controlled, single-centre study (CLAIM) at the Fraunhofer Institute of Toxicology and Experimental Medicine (Hannover, Germany), a specialty clinic. Eligible participants were patients aged at least 40 years with COPD, pulmonary hyperinflation (defined by a baseline residual volume >135% of predicted), a smoking history of at least ten pack-years, and airflow limitation (FEV 1 <80% predicted and post-bronchodilator FEV 1 : forced vital capacity <0·7). Patients with stable cardiovascular disease were eligible, but those with arrhythmias, heart failure, unstable ischaemic heart disease, or uncontrolled hypertension were not. We randomly assigned participants (1:1) to either receive a combined inhaled dual bronchodilator containing the LABA indacaterol (110 μg as maleate salt) plus the LAMA glycopyrronium (50 μg as bromide salt) once per day for 14 days, followed by a 14-day washout, then a matched placebo for 14 days, or to receive the same treatments in reverse order. The randomisation was done using lists and was concealed from patients and investigators. The primary endpoint was the effect of indacaterol-glycopyrronium versus placebo on left-ventricular end-diastolic volume measured by MRI done on day 1 (visit 4) and day 15 (visit 5) in treatment period 1 and on day 29 (visit 6) and day 43 (visit 7) in treatment period 2 in the per-protocol population. Left-ventricular end-diastolic volume was indexed to body surface area. Safety was assessed in all participants who received

  9. Nanostructured silicate polymer concrete

    Directory of Open Access Journals (Sweden)

    Figovskiy Oleg L'vovich

    2014-03-01

    Full Text Available It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18~20 %, low strength and insufficient water resistance. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block superficial pores and reduce concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. The experiments showed, that the strength and density of silicate polymer concrete increase in case of decreasing liquid glass content. The authors obtained optimal content of silicate polymer concrete, which possesses increased strength, durability, density and crack-resistance. Diffusive permeability of concrete and its chemical resistance has been investigated in various corroding media.

  10. Evaluation of recycled concrete as aggregate in new concrete pavements.

    Science.gov (United States)

    2014-04-01

    This study evaluated the use of recycled concrete as coarse aggregate in new concrete pavements. : Recycled concrete aggregate (RCA) produced from demolished pavements in three geographically dispersed locations in Washington state were used to perfo...

  11. Concrete portable handbook

    CERN Document Server

    Woodson, R Dodge

    2011-01-01

    Whether or not, you are on the job site or back in the office, this book will help you to avoid mistakes, code violations, and wasted time and money. The book's four part treatment begins with constituent materials followed by self contained parts on Concrete Properties, Processes, and Concrete Repair and Rehabilitation. Designed to be an ""all in one"" reference, the author includes a wealth information for the most popular types of testing. This includes: Analysis of Fresh Concrete; Testing Machines; Accelerated Testing Methods; Analysis of Hardened Concrete and Mortar; Core Sampl

  12. Preparing for faster filling

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Following the programmed technical stop last week, operators focussed on preparing the machine for faster filling, which includes multibunch injection and a faster pre-cycle phase.   The LHC1 screen shot during the first multibunch injection operation. The LHC operational schedule incorporates a technical stop for preventive maintenance roughly every six weeks of stable operation, during which several interventions on the various machines are carried out. Last week these included the replacement of a faulty magnet in the SPS pre-accelerator, which required the subsequent re-setting of the system of particle extraction and transfer to the LHC. At the end of last week, all the machines were handed back for operation and work could start on accommodating all the changes made into the complex systems in order for normal operation to be resumed. These ‘recovery’ operations continued through the weekend and into this week. At the beginning of this week, operators succeeded in pro...

  13. Durability Properties of Palm Oil Fuel Ash Self Compacting Concrete

    Directory of Open Access Journals (Sweden)

    T. Ofuyatan

    2015-02-01

    Full Text Available Self Compacting Concrete (SCC is a new innovation in technology that can flow readily into place under its own self weight and fill corner areas of reinforcement structures without the need to vibrate and without segregation of its constitute. The problem of durability of concrete structures due to inadequate compaction by skilled workers has become a source of concern globally. The shortage of skilled manpower, noise and vibration of equipment on construction sites has led to the development of self compacting concrete. This paper presents an experimental study on the durability properties of Self Compacting Concrete with partial placement of Palm Oil Fuel Ash (POFA. Twelve POFA self-compacting concretes of various strength grades were designed at varying percentages of 0, 5, 10, 15, 20, 25 and 30%. The concrete with no placement of ash served as control. Conplast SP432MS was used as superplasticiser in the mix. The experiments are carried out by adopting a water-powder ratio of 0.36. Workability of the fresh concrete is determined by using tests such as: slump flow, T50, V-funnel and L-Box tests. The durability of concrete is tested by acid resistance, sulphate attack and saturated water absorption at the age of 14, 28, 56 and 90 days.

  14. LIGHTWEIGHT CONCRETE BASED GRANSHLAK

    Directory of Open Access Journals (Sweden)

    NETESA M. I.

    2016-02-01

    Full Text Available Raising of problem. Concrete advisable to obtain a low strength with local secondary resources for recycling and reduce the environmental burden on the environment. But it is important to design such concrete compositions with a reduced flow of cement. It is known that the coefficient of efficiency of use of cement in the concrete of the heavy and B10 is less than about 0.5, which is almost two times smaller than in class B15 concrete and above. Even lower coefficient of efficiency in light concrete cement low strength. Therefore, it is important to find patterns determining the composition of lightweight concrete based on local-products industry with more efficient use of cement in them. Purpose.. Based on the analysis of earlier research results, including with the use of methods of mathematical planning of experiments to determine the concrete contents, which can provide the requirements for the underlying layers of the floor, the compressive strength of which should correspond to the class B5. It is important to provide the required strength at minimum flow of the cement, which is the most expensive and energy-intensive part of concrete. Conclusion. Analysis of the test results of control samples of concrete in 28-day-old, the following laws. The required tensile strength of concrete compressive strength of 7.0 MPa can be obtained in the test range when used in formulations as a filler as the Dnieper hydroelectric power station fly ash and tailings Krivoy Rog iron ore YuGOK. To ensure providing the required characteristic strength of the concrete in the underlying layers of the floor is advisable to use a nominal composition per cubic meter of concrete: cement 160 kg granshlaka Plant named after Petrovsky, 675 kg of fly ash Dnieper HPP 390 kg, 400 kg of sand, 230 liters of water. Thus, while ensuring rational grain composition components can obtain the desired strength lightweight concrete based granshlaka plant Petrovsky, using as fillers

  15. Bulk-Fill Resin Composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

    2015-01-01

    the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

  16. Improvement of performance of ultra-high performance concrete based composite material added with nano materials

    Directory of Open Access Journals (Sweden)

    Pang Jinchang

    2016-03-01

    Full Text Available Ultra-high performance concrete (UHPC, a kind of composite material characterized by ultra high strength, high toughness and high durability. It has a wide application prospect in engineering practice. But there are some defects in concrete. How to improve strength and toughness of UHPC remains to be the target of researchers. To obtain UHPC with better performance, this study introduced nano-SiO2 and nano-CaCO3 into UHPC. Moreover, hydration heat analysis, X-Ray Diffraction (XRD, mercury intrusion porosimetry (MIP and nanoindentation tests were used to explore hydration process and microstructure. Double-doped nanomaterials can further enhance various mechanical performances of materials. Nano-SiO2 can promote early progress of cement hydration due to its high reaction activity and C-S-H gel generates when it reacts with cement hydration product Ca(OH2. Nano-CaCO3 mainly plays the role of crystal nucleus effect and filling effect. Under the combined action of the two, the composite structure is denser, which provides a way to improve the performance of UHPC in practical engineering.

  17. Application of concrete to the treatment and disposal of radioactive waste in Japan

    International Nuclear Information System (INIS)

    Maki, Yasuro; Ohnuma, Hiroshi

    1992-01-01

    The paper presents the present state of application of concrete to treatment, storage and disposal of low level radioactive waste in Japan. In the 2nd section, the electric power supply and the kinds and volumes of radioactive waste from nuclear power plants in Japan are described. In the 3rd section, the applications of concrete to the treatment of radioactive waste are described. These are solidification with cement and containers made by various mortars and concretes. The application of concrete to disposal structures are presented in the 4th section; these are research on the durabity of concrete under disposal site condition, research on the filling the concrete pit with 200 l drum packed cement solidified wastes by prepacked concreting methods, and so on. And this section describes also the outlines of the low level radioactive disposal system at the Rokkasho site. (orig./DG)

  18. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    The durability of MOC concrete compositions against extreme environmental conditions viz. heating–cooling, freezing–thawing, wetting–drying and penetration and deposition of salts etc were investigated. The results reveal that MOC concrete has high compressive strength associated with high flexural strength and the ...

  19. Radiographic testing of concrete

    International Nuclear Information System (INIS)

    Porter, James F.

    1997-01-01

    The increase in construction activity in the Philippines, reinforced concrete building is still a favorite among designers, because it is much cheaper to build and it requires qualified welders, etc. and extensive nondestructive testing and inspection of metals, welds and castings. Of all the techniques radiography is widely used for concrete

  20. Concrete deck material properties.

    Science.gov (United States)

    2009-01-01

    The two-fold focus of this study was (a) to develop an understanding of the mechanisms responsible for causing : cracking in the concrete; and (b) to study the influence of the local materials on the performance of NYSDOTs HP : concrete mixture. R...

  1. Concrete-Design

    Directory of Open Access Journals (Sweden)

    Leczovics Péter

    2014-12-01

    Full Text Available Present paper introduces a new interpretation of concrete, demonstrating some extreme possibilities of this rigid material such as a design element. In the first part a brief overview of the previous achievements are shown. The second part of this paper focuses on the relationship between concrete and fashion.

  2. Danish High Performance Concretes

    DEFF Research Database (Denmark)

    Nielsen, M. P.; Christoffersen, J.; Frederiksen, J.

    1994-01-01

    In this paper the main results obtained in the research program High Performance Concretes in the 90's are presented. This program was financed by the Danish government and was carried out in cooperation between The Technical University of Denmark, several private companies, and Aalborg University...... concretes, workability, ductility, and confinement problems....

  3. Concrete, hardened: Self desiccation

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Persson, Bertil

    1999-01-01

    The test method covers the determination of internal relative humidity (RH) in hardened concrete and cement mortar using RH instruments. The determination of RH is done on crushed samples of concrete or cement motar. This test method is only for measuring equipment which gives off or takes up...

  4. concrete5 Beginner's Guide

    CERN Document Server

    Laubacher, Remo

    2011-01-01

    This book is part of Packt's Beginner's Guide series. You will be guided through the set up of a Concrete5 site with step-by-step practical examples. This book is ideal for developers who would like to build their first site with Concrete5. Some k

  5. Short steel and concrete columns under high temperatures

    Directory of Open Access Journals (Sweden)

    A. E. P. G. A. Jacintho

    Full Text Available The growing demand for knowledge about the effect of high temperatures on structures has stimulated increasing research worldwide. This article presents experimental results for short composite steel and concrete columns subjected to high temperatures in ovens with or without an axial compression load, numerically analyzes the temperature distribution in these columns after 30 and 60 minutes and compares them with experimental results. The models consist of concrete-filled tubes of three different thicknesses and two different diameters, and the concrete fill has conventional properties that remained constant for all of the models. The stress-strain behavior of the composite columns was altered after exposure to high temperatures relative to the same columns at room temperature, which was most evident in the 60-minute tests due to the higher temperatures reached. The computational analysis adopted temperature rise curves that were obtained experimentally.

  6. Radiation shielding concrete

    International Nuclear Information System (INIS)

    Kunishima, Shigeru.

    1990-01-01

    The radiation shielding concretes comprise water, cement, fine aggregates consisting of serpentines and blown mist slags, coarse aggregates consisting of serpentines and kneading materials. Since serpentines containing a relatively great amount of water of crystallization in rocks as coarse aggregates and fine aggregates, the hydrogen content in the radiation shielding concretes is increased and the neutron shielding effect is improved. In addition, since serpentines are added as the fine aggregates and blown mists slags of a great specific gravity are used, the specific gravity of the shielding concretes is increased to improve the γ-ray shielding effect. Further, by the use of the kneading material having a water reducing effect and fluidizing effect, and by the bearing effect of the spherical blown mist slags used as the fine aggregates, concrete fluidity can be increased. Accordingly, workability of the radiation shielding concretes can be improved. (T.M.)

  7. Concrete quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Holz, N. [Harza Engineering Company, Chicago, IL (United States)

    2000-08-01

    This short article reports on progress at the world's largest civil construction project, namely China's Three Gorges hydro project. Work goes on around the clock to put in place nearly 28 M m{sup 3} of concrete. At every stage of the work there is strong emphasis on quality assurance (QA) and concrete is no exception. The US company Harza Engineering has been providing QA since the mid-1980s and concrete QA has been based on international standards. Harza personnel work in the field with supervisors developing educational tools for supervising concrete construction and quality, as well as providing training courses in concrete technology. Some details on flood control, capacity, water quality and environmental aspects are given..

  8. Application of the fluid dynamics model to the field of fibre reinforced self-compacting concrete

    DEFF Research Database (Denmark)

    Svec, Oldrich; Skocek, Jan; Stang, Henrik

    Ability to properly simulate a form filling process with steel fibre reinforced self-compacting concrete is a challenging task. Such simulations may clarify the evolution of fibre orientation and distribution which in turn significantly influences final mechanical properties of the cast body. We...... have developed such a computational model and briefly introduce it in this paper. The main focus of the paper is towards validation of the ability of the model to properly mimic the flow of the fibre reinforced self-compacting concrete. An experiment was conducted where a square slab was filled...... behaviour of the self-compacting fibre reinforced concrete....

  9. Application of Crushed Concrete in Geotechnical Engineering - Selected Issues

    Science.gov (United States)

    Kawalec, Jacek; Kwiecien, Slawomir; Pilipenko, Anton; Rybak, Jarosław

    2017-12-01

    The reuse of building materials becomes an important issue in sustainable engineering. As the technical requirements for civil engineering structures changes with time and the life time is limited, the need of building new objects meets the necessity of recycling of the existing ones. In the case of steel structures, the possibility of recycling is obvious, also in the case of wooden constructions, the possibility of “burning” solves the problem. The concrete waste is generated mainly as a result of the demolition and reconstruction of residential and industrial buildings. These types of waste are basically made from crushed rocks and cement minerals and contain non-hydrated cement particles in its composition. Concrete poses a lot of problems mainly for two reasons. It is difficult to crush, heavy and hard to transport and demanding in reuse. Different fractions (particle sizes) may be used for different purposes. Starting from very fine particles which can be used in concrete production, through regular 16-300 mm fractions used to form new fills and fill the mats, up to very irregular mixtures used to form stone columns by means of Impulse Compaction or in Dynamic Replacement. The presented study juxtaposes authors experience with crushed concrete used in civil engineering, mainly in geotechnical projects. Authors’ experiences comprise the application of crushed concrete in the new concrete production in Russia, changing pulverized bridge into the fill of mesh sacks, or mattresses used as an effective way to protect the shoreline and the New Orleans East land bridge after Katrina storm (forming a new shoreline better able to withstand wave actions), and finally the use of very irregular concrete fractions to form stone columns in week soils on the example of railway and road projects in Poland. Selected case studies are presented and summarized with regard to social, technical and economic issues including energy consumption needed for proposed technologies

  10. Concrete sample point: 304 Concretion Facility

    International Nuclear Information System (INIS)

    Rollison, M.D.

    1995-01-01

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis

  11. Performance of Waterless Concrete

    Science.gov (United States)

    Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

    2010-01-01

    The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

  12. Electrokinetic decontamination of concrete

    International Nuclear Information System (INIS)

    Lomasney, H.L.; SenGupta, A.K.; Yachmenev, V.

    1996-01-01

    ELECTROSORB Electrokinetic Extraction Technology, developed by ISOTRON Corp., offers a cost-effective approach to treating contaminated concrete. Heavy metals/radionuclides trapped in concrete can be extracted using this process if they are chemically solubilized; solubilizers used are citric acid alone and a mixture of citric and nitric acids. A DC electric field is applied across the contaminated concrete to electrokinetically transport the solubilized contaminants from the concrete pores to a collector on the concrete surface. The collector is an extraction pad laid on the surface. The pad provides confinement for a planar electrode and solubilizer solution; it is operated under a vacuum to hold the pad against the concrete surface. Operation requires little attendance, reducing the workers' health hazards. The process incorporates a mechanism for recycling the solubilizer solution. A field demonstration of the process took place in Building 21 of DOE's Mound facility in Miamisburg, OH, over 12 days in June 1996. The thorium species present in this building's concrete floors included ThO 2 and thorium oxalate. The nitric acid was found to facilitate Th extraction

  13. Steel fiber reinforced concrete

    International Nuclear Information System (INIS)

    Baloch, S.U.

    2005-01-01

    Steel-Fiber Reinforced Concrete is constructed by adding short fibers of small cross-sectional size .to the fresh concrete. These fibers reinforce the concrete in all directions, as they are randomly oriented. The improved mechanical properties of concrete include ductility, impact-resistance, compressive, tensile and flexural strength and abrasion-resistance. These uniqlte properties of the fiber- reinforcement can be exploited to great advantage in concrete structural members containing both conventional bar-reinforcement and steel fibers. The improvements in mechanical properties of cementitious materials resulting from steel-fiber reinforcement depend on the type, geometry, volume fraction and material-properties of fibers, the matrix mix proportions and the fiber-matrix interfacial bond characteristics. Effects of steel fibers on the mechanical properties of concrete have been investigated in this paper through a comprehensive testing-programme, by varying the fiber volume fraction and the aspect-ratio (Lid) of fibers. Significant improvements are observed in compressive, tensile, flexural strength and impact-resistance of concrete, accompanied by marked improvement in ductility. optimum fiber-volume fraction and aspect-ratio of steel fibers is identified. Test results are analyzed in details and relevant conclusions drawn. The research is finally concluded with future research needs. (author)

  14. Evaluation and Comparison of Freeze-Thaw Tests and Air Void Analysis of Pervious Concrete

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Kevern, John T.

    2016-01-01

    Pearl-Chain Bridge technology is an innovative precast arch bridge solution which uses pervious concrete as fill material. To ensure longevity of the bridge superstructure it is necessary that the per-vious concrete fill is designed to be freeze-thaw durable; however, no standards exist on how...... to eval-uate the freeze-thaw resistance of fresh or hardened pervious concrete and correspondingly what constitutes acceptable freeze-thaw durability. A greater understanding of the correlation between the freeze-thaw performance and the air void structure of pervious concrete is needed. In the present...... study six pervious concrete mixes were exposed to freeze-thaw testing, and their air void structure was analyzed using an automated linear-traverse method. It was found that there is a miscorrelation between these two test methods in their assumption of whether or not the large interconnected voids...

  15. Effect of insulating concrete forms in concrete compresive strength

    Science.gov (United States)

    Martinez Jerez, Silvio R.

    The subject presented in this thesis is the effect of Insulating Concrete Forms (ICF's) on concrete compressive strength. This work seeks to identify if concrete cured in ICF's has an effect in compressive strength due to the thermal insulation provided by the forms. Modern construction is moving to energy efficient buildings and ICF's is becoming more popular in new developments. The thesis used a concrete mixture and a mortar mixture to investigate the effects of ICF's on concrete compressive strength. After the experimentations were performed, it was concluded that the ICF's do affect concrete strength. It was found that the forms increase concrete strength without the need for additional curing water. An increase of 50% in strength at 56 days was obtained. It was concluded that the longer concrete cures inside ICF's, the higher strength it reaches, and that ICF's effect on concrete strength is proportional to volume of concrete.

  16. Concrete and criticality

    International Nuclear Information System (INIS)

    Carter, R.D.

    1978-01-01

    Concrete is a widely used structural material which occurs frequently in systems requiring criticality analyses. Ordinarily, we give little thought to what its actual composition is (as compared to reference compositions), yet in criticality safety, differences in composition can cause large changes in k-effective and it may not be easy to predict in which direction the change will occur. Concrete composition is quite variable with differences in the aggregate used in the concrete in various parts of the country providing relative large differences in k-effective. The water content of concrete can also strongly affect the reactivity of a system in which it acts as a reflector or is interspersed between fissile units. Because concrete is so common and is often (but not always) a better reflector than water, one must know the concrete compositions or be prepared to use a ''worst case'' composition. It may be a problem, however, to determine just what is the worst case. At the Hanford Plant, the aggregate normally used is basalt, which gives a composition very low in carbon as opposed to those areas (e.g., Oak Ridge) where the use of limestone aggregate will result in concrete with a high carbon content. The data presented show some of the effects found in situations using ''Hanford'' concrete, but similar effects might be found with other compositions. In some cases, the use of concrete may be incidental to the effects shown. While the numbers shown are those for actual systems, the primary intent is to alert the reader that these effects can occur. In applying this information, the analyst should use material specific to the systems being analyzed

  17. Biodecontamination of concrete

    International Nuclear Information System (INIS)

    Hamilton, M.A.; Rogers, R.D.; Benson, J.

    1996-01-01

    A novel technology for biologically decontaminating concrete is being jointly developed by scientists at the Idaho National Engineering Laboratory (INEL) and British Nuclear Fuels plc (BNFL). The technology exploits a naturally occurring phenomenon referred to as microbially influenced degradation (MID) in which bacteria produce acids that dissolve the cement matrix of concrete. Most radionuclide contamination of concrete is fixed in the outer few mm of the concrete surface. By capturing and controlling this natural process, a biological method of removing the surface of concrete to depths up to several mm is being developed. Three types of bacteria are known to be important in MID of concrete: nitrifying bacteria that produce nitric acid, sulfur oxidizing bacteria that produce sulfuric acid, and certain heterotrophic bacteria that produce organic acids. An investigation of natural environments demonstrated with scanning electron microscopy the presence of bacteria on concrete surfaces of a variety of structures, such as bridges and dams, where corrosion is evident. Enumeration of sulfur oxidizing and nitrifying bacteria revealed their presence and activity on structures to varying degrees in different environments. Under ideal conditions, Thiobacillus thiooxidans, a sulfur oxidizing bacteria, attached to and colonized the surface of concrete specimens. Over 1mm depth of material from a 10 cm x 10 cm square surface was removed in 68 days in the Thiobacillus treated specimen compared to a sterile control. Laboratory and field demonstrations are currently being conducted using experimental chambers designed to be mounted directly to concrete surfaces where radionuclide contamination exists. Data is being obtained in order to determine actual rates of surface removal and limitations to the system. This information will be used to develop a full scale decontamination technology

  18. concrete5 cookbook

    CERN Document Server

    Strack, David

    2013-01-01

    The Cookbook-style recipes allow you to go both directly to your topic of interest or follow topics throughout a chapter to gain in-depth knowledge. This practical Cookbook will cater to the needs of both intermediate and advanced concrete5 developers.This book is geared towards intermediate to advanced PHP developers who would like to learn more about the concrete5 content management system. Developers already familiar with concrete5 will learn new time-saving tricks and will find the book to be a great reference tool.

  19. Concrete = aggregate, cement, water?

    International Nuclear Information System (INIS)

    Jelinek, J.

    1990-01-01

    Concrete for the Temelin nuclear power plant is produced to about 70 different formulae. For quality production, homogeneous properties of aggregates, accurate proportioning devices, technological discipline and systematic inspections and tests should be assured. The results are reported of measuring compression strength after 28 days for different concrete samples. The results of such tests allow reducing the proportion of cement, which brings about considerable savings. Reduction in cement quantities can also be achieved by adding ash to the concrete mixes. Ligoplast, a plasticizer addition is used for improving workability. (M.D). 8 figs

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

    OpenAIRE

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

    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. COMPARATIVE STUDY OF GLASS FIBRE CONCRETE AND NORMAL CONCRETE

    OpenAIRE

    Mr.Yogesh S.Lanjewar*

    2018-01-01

    Concrete is basically the most important material concerning with the construction and infrastructural procedures, for which it should be of good strength and durability. Many researches are being conducted to make concrete more sustainable and of more strength and durability. Therefore keeping this in mind i have chosen to do the comparative study regarding the strength of normal concrete with the glass fibre added concrete using mix design procedure as per IS 10262-2009 for concrete. As w...

  2. Electrokenitic Corrosion Treatment of Concrete

    Science.gov (United States)

    Cardenas, Henry E (Inventor)

    2015-01-01

    A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

  3. Electrokinetic Strength Enhancement of Concrete

    Science.gov (United States)

    Cardenas, Henry E. (Inventor)

    2016-01-01

    A method and apparatus for strengthening cementitious concrete by placing a nanoparticle carrier liquid in contact with a first surface of a concrete section and inducing a current across the concrete section at sufficient magnitude and for sufficient time that nanoparticles in the nanoparticle carrier liquid migrate through a significant depth of the concrete section.

  4. Shrinkage Reducing Admixture for Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Concrete shrinkage cracking is a common problem in all types of concrete structures, especially for structures and environments where the cracks are prevalent and the repercussions are most severe. A liquid shrinkage reducing admixture for concrete, developed by GRACE Construction Products and ARCO Chemical Company, that reduces significantly the shrinkage during concrete drying and potentially reduces overall cracking over time.

  5. A historical examination of concrete

    International Nuclear Information System (INIS)

    Mallinson, L.G.; Li Davies, I.

    1987-01-01

    The requirement that concrete in radioactive waste repositories be stable physically and chemically for very long times has initiated studies of ancient and old concretes. This report is a contribution to this effort. After a description of the history of cement and concrete, the published literature relating to the analysis of old and ancient concrete is reviewed. A series of samples spanning the history of concrete has been obtained; a variety of physical and chemical techniques have been employed to characterize these samples. Reasons for survival of ancient concretes, and for durability of early, reinforced concretes are identified. Recommendations for further studies are given. 132 refs

  6. Gas-filled hohlraum fabrication

    International Nuclear Information System (INIS)

    Salazar, M.A.; Gobby, P.L.; Foreman, L.R.; Bush, H. Jr.; Gomez, V.M.; Moore, J.E.; Stone, G.F.

    1995-01-01

    Los Alamos National Laboratory (LANL) researchers have fabricated and fielded gas-filled hohlraums at the Lawrence Livermore National Laboratory (LLNL) Nova laser. Fill pressures of 1--5 atmospheres have been typical. We describe the production of the parts, their assembly and fielding. Emphasis is placed on the production of gas-tight polyimide windows and the fielding apparatus and procedure

  7. Anchorage in concrete construction

    CERN Document Server

    Eligehausen, Rolf; Silva, John F

    2013-01-01

    A comprehensive treatment of current fastening technology using inserts (anchor channels, headed stud), anchors (metal expansion anchor, undercut anchor, bonded anchor, concrete screw and plastic anchor) as well as power actuated fasteners in concrete. It describes in detail the fastening elements as well as their effects and load-bearing capacities in cracked and non-cracked concrete. It further focuses on corrosion behaviour, fire resistance and characteristics with earthquakes and shocks. It finishes off with the design of fastenings according to the European Technical Approval Guideline (ETAG 001), the Final Draft of the CEN Technical Specification 'Design of fastenings for use in concrete' and the American Standards ACI 318-05, Appendix D and ACI 349-01, Appendix B.

  8. Concrete Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This is a 20,000-sq ft laboratory that supports research on all aspects of concrete and materials technology. The staff of this facility offer wide-ranging expertise...

  9. Prestressed concrete design

    CERN Document Server

    Hurst, MK

    1998-01-01

    This edition provides up-to-date guidance on the detailed design of prestressed concrete structures. All major topics are dealt with, including prestressed flat slabs, an important and growing application in the design of buildings.

  10. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    TECS

    exposure to water and salt attack by replacing 10% magnesium chloride solution by magnesium sulphate solution ... Having tremendous load bearing capacity, it can withstand .... retention coefficients for similar concrete compositions.

  11. Improving concrete overlay construction.

    Science.gov (United States)

    2010-03-01

    Several road construction projects involving concrete overlays at the state and county levels in Iowa in 2009 were studied for : construction techniques and methods. The projects that were evaluated consisted of sites in four Iowa counties: Osceola, ...

  12. Concrete decontamination scoping tests

    International Nuclear Information System (INIS)

    Archibald, K.E.

    1995-01-01

    This report details the research efforts and scoping tests performed at the Idaho Chemical Process Plant using scabbling, chemical, and electro-osmotic decontamination techniques on radiologically contaminated concrete

  13. Modeling reinforced concrete durability.

    Science.gov (United States)

    2014-06-01

    This project developed a next-generation modeling approach for projecting the extent of : reinforced concrete corrosion-related damage, customized for new and existing Florida Department of : Transportation bridges and suitable for adapting to broade...

  14. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.; Cachim, P.B.; Da Costa, Pedro M. F. J.

    2014-01-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  15. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.

    2014-04-01

    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  16. Prototype steel-concrete LEP dipole magnet

    CERN Multimedia

    1981-01-01

    The magnetic field needed in the LEP dipole magnets was rather low, of a fraction of tesla. This lead to the conception of a novel yoke structure consisting of stacks of 1.5 mm thick low-carbon steel laminations spaced by 4.1 mm with the spaces filled with concrete. The excitation coils were also very simple: aluminium bars insulated by polyester boxes in this prototype, by glass-epoxy in the final magnets. For details see LEP-Note 118,1978 and LEP-Note 233 1980. See also 8111529,7908528X.

  17. Recycling of concrete

    International Nuclear Information System (INIS)

    Halaszovich, S.

    1988-01-01

    The paper reviews potentials and problems of disposal or recycling of concrete removed from nuclear installations. Due to the difficulties in determining radioactivity limits that are compatible with utilization of recycled material in practice, a method is proposed that takes into account inhalation of dusts, as occurring during the reprocessing or recycling of the concrete, for instance in road building. This method is based on the maximum permissible radioactivity uptake by inhalation of a nuclide mixture of unknown composition. (RB) [de

  18. Sulfur polymer cement concrete

    International Nuclear Information System (INIS)

    Weber, H.H.; McBee, W.C.

    1990-01-01

    Sulfur-based composite materials formulated using sulfur polymer cement (SPC) and mineral aggregates are described and compared with conventional portland cement based materials. Materials characteristics presented include mechanical strength, chemical resistance, impact resistance, moisture permeation, and linear shrinkage during placement and curing. Examples of preparation and placement of sulfur polymer cement concrete (SC) are described using commercial scale equipment. SC applications presented are focused into hostile chemical environments where severe portland cement concrete (PCC) failure has occurred

  19. ADVANCEMENTS IN CONCRETE TECHNOLOGY

    OpenAIRE

    Shri Purvansh B. Shah; Shri Prakash D. Gohil; Shri Hiren J. Chavda; Shri Tejas D. Khediya

    2015-01-01

    Developing and maintaining world’s infrastructure to meet the future needs of industrialized and developing countries is necessary to economically grow and improve the quality of life. The quality and performance of concrete plays a key role for most of infrastructure including commercial, industrial, residential and military structures, dams, power plants. Concrete is the single largest manufactured material in the world and accounts for more than 6 billion metric tons of materials annual...

  20. Performance of "Waterless Concrete"

    Science.gov (United States)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  1. Fracture Mechanics of Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, Jens Peder

    Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...... and the goveming equations are explicit and simple. These properties of the model make it a very powerful tool, which is applicable for the designing engineer. The method is also extended to reinforced concrete, where the results look very promising. The large experimental investigation on high-strength concrete...

  2. Fibre-concrete container

    International Nuclear Information System (INIS)

    2000-01-01

    In this leaflet the fibre-concrete container for radioactive wastes is described. The fibre container is made of fibre-concrete that contains cement, aggregate, sand, filter, flame-silica, super-plastificator, water and scattered metal fibres. The fibre-concrete container has a dice shape with outer dimension 1.7 x 1.7 x 1.7 m. It is mounted of a container body, a container cover and two caps. Total weight of container is 4,240 kg, maximum weight of loaded container do not must exceed 15,000 kg. The physical and mechanical properties of the fibre-concrete container are described in detail. The fibre-concrete container manufactured for storing of low and intermediate radioactive wastes. A fibre-concrete container utilization to store of radioactive wastes solves these problems: increase of stability of stored packages of radioactive waste; watertightness within 300 years at least; static stability of bearing space; better utilization of bearing spaces; insulation of radioactive waste in a case of seismic and geological event; increase of fire resistance; and transport of radioactive waste

  3. Concrete radiation shielding

    International Nuclear Information System (INIS)

    Kaplan, M.F.

    1989-01-01

    The increased use of nuclear energy has given rise to a growth in the amount of artificially produced radiation and radioactive materials. The design and construction of shielding to protect people, equipment and structures from the effects of radiation has never been more important. Experience has shown that concrete is an effective, versatile and economical material for the construction of radiation shielding. This book provides information on the principles governing the interaction of radiation with matter and on relevant nuclear physics to give the engineer an understanding of the design and construction of concrete shielding. It covers the physical, mechanical and nuclear properties of concrete; the effects of elevated temperatures and possible damage to concrete due to radiation; basic procedures for the design of concrete radiation shields and finally the special problems associated with their construction and cost. Although written primarily for engineers concerned with the design and construction of concrete shielding, the book also reviews the widely scattered data and information available on this subject and should therefore be of interest to students and those wishing to research further in this field. (author)

  4. Separation of contaminated concrete

    International Nuclear Information System (INIS)

    Bakiewicz, J.L.; Reymer, A.P.S.

    1990-01-01

    Separating the contaminated parts from the non-contaminated parts from decommissioned nuclear facilities may strongly reduce the amount of contaminated concrete. The reduction in volume of the radioactive contaminated concrete is dependent on how much cementstone is in the concrete. This research program shows that the radioactive contamination is mostly in the cementstone. However the choice that the cementstone parts, (or better said the radioactive parts) are smaller than 1 mm may not always be true. Normally the cementstone takes about 30% of the total concrete volume. A separation procedure composed by a combination of milling and thermal shock has been assessed. Both the cold and hot thermal shock in combination with milling are not able to separate the cementstone from the larger aggregates completely. However, the cementstone from the concrete with a low nominal grain size seems to be almost completely removed by the combination cold thermal shock/milling, while the cementstone from the concrete with a high nominal grain size seems to be almost completely removed by the combination hot thermal shock/milling. After both methods a layer of cementstone was still visible on the aggregates. Washing followed by a nitric acid treatment removed each 2 wt% of cementstone

  5. Egalité filles-garçons : un objectif à l’épreuve du double usage des dispositifs d’accompagnement à la scolarité Girl-boy equality: an objective against specific help project’s dual-use

    Directory of Open Access Journals (Sweden)

    Cyrille Morin

    2011-10-01

    Full Text Available Cet article propose un regard sur l’égalité scolaire filles-garçons par le biais des dispositifs d’accompagnement à la scolarité en collectif, c'est-à-dire en équipements de quartier. Basé sur une recherche ethnographique, il s’interroge plus précisément sur la manière dont les enfants s’approprient les dispositifs d’accompagnement proposés. Les premiers résultats montrent qu’ils en ont un « double usage » de soutien scolaire et d’aide aux devoirs, mais aussi de socialisation et d’apprentissages des rôles parentaux, notamment par les filles. Les enfants sont « libres » de fréquenter l’un ou l’autre des dispositifs du quartier. Cette « liberté » s’exerce dans une logique d’appropriation sexuée du quartier comme territoire de jeux et de socialisation qui entre en correspondance avec les spécialisations de l’offre d’accompagnement scolaire locale. Cette correspondance n’est pas sans rappeler les rapports socio-sexués au savoir, qui sont construits au sein de l’école. Ainsi, on constate d’une part que l’appropriation est genrée et d’autre part qu’elle reflète les scolarités proposées aux filles et aux garçons. En ne tenant pas compte de la socialisation sexuée et des rapports socio-sexués au savoir, les dispositifs vont dans le sens des inégalités de genre en construction chez les jeunes.This article looks at gender inequality in specific help projects for students. In French city suburbs, children are offered to get some extra homework help. These projects are implemented by associations in order to help students who need to be explained how to learn and do their homework. Based on an ethnographic approach, this research tried to determine how children appropriate themselves this help. First results indicate that children have a “dual use” of homework help projects. The first use is about homework, but there is another use for girls who have to learn parental

  6. Offshore concrete structures

    International Nuclear Information System (INIS)

    Lamas Pardo, M.; Carral Couce, L. M.

    2011-01-01

    In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shiphuidling industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

  7. 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.

  8. Radiopacity of root filling materials

    International Nuclear Information System (INIS)

    Beyer-Olsen, E.M.

    1983-01-01

    A method for measuring the radiopacity of root filling materials is described. Direct measurements were made of the optic density values of the materials in comparison with a standard curve relating optic density to the thickness of an aluminium step wedge exposed simultaneously. By proper selection of film and conditions for exposure and development, it was possible to obtain a near-linear standard curve which added to the safety and reproducibility of the method. The technique of radiographic assessment was modified from clinical procedures in evaluating the obturation in radiographs, and it was aimed at detecting slits or voids between the dental wall and the filling material. This radiographic assessment of potensial leakage was compared with actual in vitro lekage of dye (basic fuchsin) into the roots of filled teeth. The result of the investigation show that root filling materials display a very wide range of radiopacity, from less than 3 mm to more than 12 mm of aluminium. It also seem that tooth roots that appear to be well obturated by radiographic evaluation, stand a good chance of beeing resistant to leakage in vitro, and that the type of filling material rather than its radiographic appearance, determines the susceptibility of the filled tooth to leakage in vitro. As an appendix the report contains a survey of radiopaque additives in root filling materials

  9. Quantifying movements of corrosion products in reinforced concrete using x-ray attenuation measurements

    DEFF Research Database (Denmark)

    Pease, Bradley Justin; Michel, Alexander; Stang, Henrik

    2011-01-01

    Corrosion of steel reinforcement, embedded in concrete, may substantially degrade concrete structures due to the expansive nature of corrosion products. Expansion of corrosion products cause tensile stresses to develop and cracks to form in concrete. Extensive research has focused on corrosion...... of corrosion products move into the concrete without generating tensile stresses and cracks in the concrete. Typically, corrosion products are thought to occupy pores, interfacial defects, and/or air voids located near the concrete-steel interface and stresses develop only after filling of these pores. Further....... X-ray attenuation measurements are also capable of detecting cracks. Therefore, this approach provides a direct measurement of the amount and location of reinforcement corrosion products required to induce cracking. Results of a parametric investigation on the impact of water-to-cement ratio (0...

  10. Usage of Crushed Concrete Fines in Decorative Concrete

    Science.gov (United States)

    Pilipenko, Anton; Bazhenova, Sofia

    2017-10-01

    The article is devoted to the questions of usage of crushed concrete fines from concrete scrap for the production of high-quality decorative composite materials based on mixed binder. The main problem in the application of crushed concrete in the manufacture of decorative concrete products is extremely low decorative properties of crushed concrete fines itself, as well as concrete products based on them. However, crushed concrete fines could have a positive impact on the structure of the concrete matrix and could improve the environmental and economic characteristics of the concrete products. Dust fraction of crushed concrete fines contains non-hydrated cement grains, which can be opened in screening process due to the low strength of the contact zone between the hydrated and non-hydrated cement. In addition, the screening process could increase activity of the crushed concrete fines, so it can be used as a fine aggregate and filler for concrete mixes. Previous studies have shown that the effect of the usage of the crushed concrete fines is small and does not allow to obtain concrete products with high strength. However, it is possible to improve the efficiency of the crushed concrete fines as a filler due to the complex of measures prior to mixing. Such measures may include a preliminary mechanochemical activation of the binder (cement binder, iron oxide pigment, silica fume and crushed concrete fines), as well as the usage of polycarboxylate superplasticizers. The development of specific surface area of activated crushed concrete fines ensures strong adhesion between grains of binder and filler during the formation of cement stone matrix. The particle size distribution of the crushed concrete fines could achieve the densest structure of cement stone matrix and improve its resistance to environmental effects. The authors examined the mechanisms of structure of concrete products with crushed concrete fines as a filler. The results of studies of the properties of

  11. Ultrasonic imaging in concrete

    International Nuclear Information System (INIS)

    Ribay, G.; Paris, O.; Rambach, J.M.

    2009-01-01

    The third and final protection barrier confining nuclear reactors is usually a concrete containment structure. Monitoring the structural integrity of these barriers is critical in ensuring the safety of nuclear power plants. The Institute for Radiological Protection and Nuclear Safety (IRSN) in France in collaboration with the French Atomic commission (CEA/LIST) has developed an ultrasonic phased-array technique capable of inspecting thick concrete walls. The non-destructive method is dedicated to detect cracks and bulk defects. Given the thickness of the structure (1.2 m) undergoing inspection and the heterogeneity of the concrete, the optimal frequency lies in the 50-300 kHz range. At these frequencies, the ultrasonic beam profiles are widespread (non-directive) with poor signal-to-noise ratio. Previous studies have shown the potential of using phased-array techniques (i.e., beam focusing and beam steering) in order to improve detection resolution and sizing accuracy. In this paper we present experimental studies performed with array up to 16 transducers working at 200 kHz. Experiments are carried out on representative concrete blocks containing artificial defects. One is a reinforced mock-up representative of the first reinforcing mesh of wall containment. Experimental results show that in spite of the reinforcement, artificial defects deep as half a meter can be detected. Reconstructed images resulting from phased array acquisitions on an artificial crack embedded in a concrete block are also presented and discussed. The presented method allows detecting oriented defects in concrete with improved signal to noise ratio and sensibility. A simulation model of the interaction of ultrasound with a heterogeneous medium like concrete is briefly commented. (authors)

  12. Removal of root filling materials.

    LENUS (Irish Health Repository)

    Duncan, H.F. Chong, B.S.

    2011-05-01

    Safe, successful and effective removal of root filling materials is an integral component of non-surgical root canal re-treatment. Access to the root canal system must be achieved in order to negotiate to the canal terminus so that deficiencies in the original treatment can be rectified. Since a range of materials have been advocated for filling root canals, different techniques are required for their removal. The management of commonly encountered root filling materials during non-surgical re-treatment, including the clinical procedures necessary for removal and the associated risks, are reviewed. As gutta-percha is the most widely used and accepted root filling material, there is a greater emphasis on its removal in this review.

  13. Better building of valley fills

    Energy Technology Data Exchange (ETDEWEB)

    Chironis, N.P.

    1980-03-01

    Current US regulations for building valley fills or head of hollow fills to hold excess spoil resulting from contour mining are meeting with considerable opposition, particularly from operators in steep-slope areas. An alternative method has been submitted to the Office of Surface Mining by Virgina. Known as the zoned concept method, it has already been used successfully in building water-holding dams and coal refuse embankments on sloping terrain. The ways in which drainage and seepage are managed are described.

  14. Let’s Get Concrete!

    DEFF Research Database (Denmark)

    Jones, Candace; Boxenbaum, Eva

    whereas in the United States market and professional logics interacted: manufacturers cooperated to create standards for concrete and appealed to architects as consumers. Our findings also illuminate that concrete was legitimated initially by imitation of stone, but this strategy soon de......-legitimated not only concrete but also stone. Concrete was perceived as merely imitative and thus inauthentic. For concrete to become a legitimate and widely adopted material, architects had to theorize concrete as unique material with distinctive aesthetic possibilities, which led to new kinds of buildings and new...... architectural styles. Our study illuminates the key role that materials and aesthetics played within architects’ professional logic and shaped processes of institutional change....

  15. Studies of historic concrete

    International Nuclear Information System (INIS)

    Jull, S.P.; Lees, T.P.

    1990-01-01

    Underground concrete repositories for nuclear waste will have to maintain their integrity for hundreds of years. This study examines ancient concretes and assesses the suitability of equivalent modern materials for underground storage. Thirty four ancient samples have been obtained from Great Britain, Austria and Italy. One 19th century sample was also collected. The samples were examined using a variety of analytical techniques (including scanning electron microscopy, optical microscopy, chemical analysis and pH determination). The samples were also subjected to a range of physical tests. Most of the samples examined were very weak and porous although they had retained full structural integrity. With the exception of the 19th century sample, none of the concretes had maintained pH alkaline enough to immobilize radionuclides. Hydrated calcium silicates have been detected in some samples which are similar to those observed in modern Portland cement concretes. These stable cementitious species have endured for almost two thousand years. All the ancient concretes and mortars examined contained natural pozzolanic material or crushed burnt clay. This may have had some effect on the reduction in alkalinity although the main reason was full carbonation of calcium hydroxide

  16. Preliminary Study on Impact Resistances of Fiber Reinforced Concrete Applied Nuclear Power Plants

    International Nuclear Information System (INIS)

    Jin, Byeong Moo; Kim, Young Jin; Jeon, Se Jin

    2013-01-01

    Studies to improve the impact resistance depending upon design parameters for fiber reinforced concrete, such as type of fibers and application ratio, are in progress. Authors assessed first the impact resistance of concrete walls depending upon fiber types and missile impact velocities. The safety assessment of nuclear power plants against large civil aircraft crashes have been accomplished for normal concrete and fiber reinforced concretes in this study. Studies on the safety assessments on the nuclear power plants against large civil aircraft crashes are ongoing actively. As a step of evaluating the applicability of fiber reinforced concrete in means of ensuring more structural safety of the nuclear power plants against impact, the impact resistance for the 1% steel and 2% polyamide fiber reinforced concretes have been evaluated. For reactor containment building structures, it seem there is no impact resistance enhancement of fiber reinforced concrete applied to reactor containment building in the cases of impact velocity 150 m/sec considered in this study. However this results from the pre-stressing forces which introduce compressive stresses in concrete wall and dome section of reactor containment building. Nonetheless there may be benefits to apply fiber reinforced concrete to nuclear power plants. For double containment type reactor containment building, the outer structure is a reinforced concrete structure. The impact resistances for non pre-stressed cylindrical reactor containment buildings are enhanced by 23 to 47 % for 2 % polyamide fiber reinforced concretes and 1 % steel fiber reinforced concretes respectively. For other buildings such as auxiliary building, compound building and fuel storage building surrounding the reactor containment building, there are so many reinforced concrete walls which are anticipated some enhancements of impact resistance by using fiber reinforced concretes. And heavier or faster large civil aircraft impacts produce higher

  17. Preliminary Study on Impact Resistances of Fiber Reinforced Concrete Applied Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Byeong Moo; Kim, Young Jin; Jeon, Se Jin [Daewoo E and C Co. Ltd., Suwon (Korea, Republic of)

    2013-10-15

    Studies to improve the impact resistance depending upon design parameters for fiber reinforced concrete, such as type of fibers and application ratio, are in progress. Authors assessed first the impact resistance of concrete walls depending upon fiber types and missile impact velocities. The safety assessment of nuclear power plants against large civil aircraft crashes have been accomplished for normal concrete and fiber reinforced concretes in this study. Studies on the safety assessments on the nuclear power plants against large civil aircraft crashes are ongoing actively. As a step of evaluating the applicability of fiber reinforced concrete in means of ensuring more structural safety of the nuclear power plants against impact, the impact resistance for the 1% steel and 2% polyamide fiber reinforced concretes have been evaluated. For reactor containment building structures, it seem there is no impact resistance enhancement of fiber reinforced concrete applied to reactor containment building in the cases of impact velocity 150 m/sec considered in this study. However this results from the pre-stressing forces which introduce compressive stresses in concrete wall and dome section of reactor containment building. Nonetheless there may be benefits to apply fiber reinforced concrete to nuclear power plants. For double containment type reactor containment building, the outer structure is a reinforced concrete structure. The impact resistances for non pre-stressed cylindrical reactor containment buildings are enhanced by 23 to 47 % for 2 % polyamide fiber reinforced concretes and 1 % steel fiber reinforced concretes respectively. For other buildings such as auxiliary building, compound building and fuel storage building surrounding the reactor containment building, there are so many reinforced concrete walls which are anticipated some enhancements of impact resistance by using fiber reinforced concretes. And heavier or faster large civil aircraft impacts produce higher

  18. Concrete and prestressing process, container made with this concrete

    International Nuclear Information System (INIS)

    Gerard, M.

    1992-01-01

    Shape memory alloy fibers or heat shrinking fibers are encapsulated in a standard concrete. Prestressed concrete is obtained by heat treatment. Application is made to the fabrication of radioactive waste containers

  19. Concrete with onyx waste aggregate as aesthetically valued structural concrete

    Science.gov (United States)

    Setyowati E., W.; Soehardjono, A.; Wisnumurti

    2017-09-01

    The utillization of Tulungagung onyx stone waste as an aggregate of concrete mixture will improve the economic value of the concrete due to the brighter color and high aesthetic level of the products. We conducted the research of 75 samples as a test objects to measure the compression stress, splits tensile stress, flexural tensile stress, elasticity modulus, porosity modulus and also studied 15 test objects to identify the concrete micro structures using XRD test, EDAX test and SEM test. The test objects were made from mix designed concrete, having ratio cement : fine aggregate : coarse aggregate ratio = 1 : 1.5 : 2.1, and W/C ratio = 0.4. The 28 days examination results showed that the micro structure of Tulungagung onyx waste concrete is similar with normal concrete. Moreover, the mechanical test results proved that Tulungagung onyx waste concretes also have a qualified level of strength to be used as a structural concrete with higher aesthetic level.

  20. Durability of lightweight concrete : Phase I : concrete temperature study.

    Science.gov (United States)

    1968-08-01

    This report describes a study conducted to determine the temperature gradient throughout the depth of a six inch concrete bridge deck. The bridge deck selected for study was constructed using lightweight concrete for the center spans and sand and gra...

  1. Experimental results on salt concrete for barrier elements made of salt concrete in a repository for radioactive waste in a salt mine

    International Nuclear Information System (INIS)

    Gutsch, Alex-W.; Preuss, Juergen; Mauke, Ralf

    2012-01-01

    The Bartensleben rock salt mine in Germany was used as a repository for low and intermediate level radioactive waste from 1971 to 1991 and from 1994 to 1998. The repository with an overall volume of about 6 million m 3 has to be closed. Salt concrete is used for the refill of the voids of the repository. The concrete mixtures contain crushed salt instead of natural aggregates as the void filling material should be as similar to the salt rock as possible. Very high requirements regarding low heat development and little or even no cracking during concrete hardening had to be fulfilled even for the barrier elements made from salt concrete which separate the radioactive waste from the environment. Requirements for the salt concrete were set up with regard to the fluidity of the fresh concrete during the hardening process and its durability. In the view of a comprehensive numerical calculations of the temperature development and thermal stresses in the massive salt concrete elements of the backfill of the voids, experimental results for material properties of the salt concrete are presented: mixture of the salt concrete, thermodynamic properties (adiabatic heat release, thermal dilatation, thermal conductivity and heat capacity), mechanical short term properties, creep (under tension, under compression), autogenous shrinkage

  2. Self compacting concrete incorporating high-volumes of fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Bouzoubaa, N. [Natural Resources Canada, Ottawa, ON (Canada). International Centre for Sustainable Development of Cement and Concrete; Lachemi, M. [Ryerson Polytechnic Univ., Toronto, ON (Canada). Dept. of Civil Engineering

    2004-07-01

    Self-compacting concrete (SCC) is now widely used in reinforced concrete structures. Fine materials such as fly ash ensure that the concrete has the necessary properties of high fluidity and cohesiveness. An experimental study was conducted in which 9 SCC mixtures and one control concrete were produced in order to evaluate SCC made with high-volumes of fly ash. The content of the cementitious materials remained constant at 400 kg/cubic metre, but the ratio of water to cementitious material ranged from 0.35 to 0.45. The viscosity and stability of the fresh concrete was determined for self-compacting mixtures of 40, 50 and 60 per cent Class F fly ash. The compressive strength and drying shrinkage were also determined for the hardened concretes. Results showed that the SCCs developed a 28-day compressive strength ranging from 26 to 48 MPa. It was concluded that high-volumes of Class F fly ash could offer the following advantages to an SCC: reduced construction time and labour cost; eliminate the need for vibration; reduce noise pollution; improve the filling capacity of highly congested structural members; and, ensure good structural performance. 19 refs., 8 tabs., 2 figs.

  3. Strength and Microstructure of Concrete with Iron Ore Tailings as Replacement for River Sand

    Science.gov (United States)

    Umara Shettima, Ali; Ahmad, Yusof; Warid Hussin, Mohd; Zakari Muhammad, Nasiru; Eziekel Babatude, Ogunbode

    2018-03-01

    River Sand is one of the basic ingredients used in the production of concrete. Consequently, continuous consumption of sand in construction industry contributes significantly to depletion of natural resources. To achieve more sustainable construction materials, this paper reports the use of iron ore tailings (IOT) as replacement for river sand in concrete production. IOT is a waste product generated from the production of iron ore and disposed to land fill without any economic value. Concrete mixtures containing different amount of IOT were designed for grade C30 with water to cement ratio of 0.60. The percentage ratios of the river sand replacements by IOT were 25%, 50%, 75% and 100%. Concrete microstructure test namely, XRD and Field Emission Scanned Electron Microscopic/Energy dispersive X-ray Spectroscopy (FESEM/EDX) were conducted for control and IOT concretes in order to determine the interaction and performance of the concrete containing IOT. Test results indicated that the slump values of 130 mm and 80 to 110 mm were recorded for the control and IOT concretes respectively. The concrete sample of 50% IOT recorded the highest compressive strength of 37.7 MPa at 28 days, and the highest flexural strength of 5.5 MPa compared to 4.7 MPa for reference concrete. The texture of the IOT is rough and angular which was able to improve the strength of the concrete.

  4. Strength and Microstructure of Concrete with Iron Ore Tailings as Replacement for River Sand

    Directory of Open Access Journals (Sweden)

    Umara Shettima Ali

    2018-01-01

    Full Text Available River Sand is one of the basic ingredients used in the production of concrete. Consequently, continuous consumption of sand in construction industry contributes significantly to depletion of natural resources. To achieve more sustainable construction materials, this paper reports the use of iron ore tailings (IOT as replacement for river sand in concrete production. IOT is a waste product generated from the production of iron ore and disposed to land fill without any economic value. Concrete mixtures containing different amount of IOT were designed for grade C30 with water to cement ratio of 0.60. The percentage ratios of the river sand replacements by IOT were 25%, 50%, 75% and 100%. Concrete microstructure test namely, XRD and Field Emission Scanned Electron Microscopic/Energy dispersive X-ray Spectroscopy (FESEM/EDX were conducted for control and IOT concretes in order to determine the interaction and performance of the concrete containing IOT. Test results indicated that the slump values of 130 mm and 80 to 110 mm were recorded for the control and IOT concretes respectively. The concrete sample of 50% IOT recorded the highest compressive strength of 37.7 MPa at 28 days, and the highest flexural strength of 5.5 MPa compared to 4.7 MPa for reference concrete. The texture of the IOT is rough and angular which was able to improve the strength of the concrete.

  5. Drying of Concrete

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Geiker, Mette Rica; Nygaard, Peter Vagn

    2002-01-01

    Estimated and measured relative humidity (RH) change during drying are compared for two concretes, 1: w/c=0.46 and 2: w/(c+0.5fa+2sf)=0.50. The estimations were undertaken by means of the Swedish program TorkaS 1.0. Measurements were performed by RH-sensors type Humi-Guard. Drying of 150 mm thick...... samples from sides at 60% RH and 22 °C took place from 4 to 56 days after casting. At the end of the drying period the measured RH was about 4% lower than the estimated RH at 1/5th depth from the exposed surface for both concretes. In the middle of the samples, the measured RH of concretes 1 and 2 were 2...

  6. Use of fiber reinforced concrete for concrete pavement slab replacement.

    Science.gov (United States)

    2014-03-01

    Unlike ordinary concrete pavement, replacement concrete slabs need to be open to traffic within 24 hours (sooner in : some cases). Thus, high early-strength concrete is used; however, it frequently cracks prematurely as a result of high : heat of hyd...

  7. Design of double containment canister cask storage system

    International Nuclear Information System (INIS)

    Asami, M.; Matsumoto, T.; Oohama, T.; Kuriyama, K.; Kawakami, K.

    2004-01-01

    Spent fuels discharged from Japanese LWR will be stored as recycled-fuel-resources in interim storage facilities. The concrete cask storage system is one of important forms for the spent fuel interim storage. In Japan, the interim storage facility will be located near the coast, therefore it is important to prevent SCC (Stress Corrosion Cracking) caused by sea salt particles and to assure the containment integrity of the canister which contains spent fuels. KEPCO, NFT and OCL have designed the double containment canister cask storage system that can assure the long-term containment integrity and monitor the containment performance without storage capacity decrease. Major features of the combined canister cask system are shown as follows: This system can survey containment integrity of dual canisters by monitoring the pressure of the gap between canisters. The primary canister has dual lids sealed by welding. The secondary canister has single lid tightened by bolts and sealed by metallic gaskets. The primary canister is contained in the transport cask during transportation, and the gap between the primary canister and the transport cask is filled with He gas. Under storage condition in the concrete cask, the primary canister is contained in the secondary canister, and the gap between these canisters is filled with helium gas. Hence this system can prevent the primary canister to contact sea salt particle in the air and from SCC. Decrease of cooling performance because of the double canister is compensated by fins fitted on the secondary canister surface. Then, this system can prevent the decrease of storage capacity determined by the fuel temperature limit. This system can assure that the primary canister will keep intact for long term storage. Therefore, in the case of pressure down of the gap between canisters, it can be considered that the secondary canister containment is damaged, and the primary canister will be transferred to another secondary canister at the

  8. Concentrated loads on concrete

    DEFF Research Database (Denmark)

    Lorenzen, Karen Grøndahl; Nielsen, Mogens Peter

    1997-01-01

    This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas are devel......This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas...

  9. Sprayed concrete linings

    Energy Technology Data Exchange (ETDEWEB)

    Hindle, D.

    1999-12-01

    Sprayed concrete, or shotcrete, was invented in the 1920s for preserving dinosaur skeletons and was used underground initially in coalmines for the preservation and fine proofing of timber supports. Its use as a support lining in rock tunnelling was developed in the 1950s and 60s. The article surveys equipment available from major manufacturers and suppliers of concrete spraying equipment (Aliva, Cifa, GIA, Industri, Ingersoll Rand, etc.), specialist cement and additive manufacturers (Castle, Cement, Moria Carbotech). manufacturers of lattice girders and fibre reinforcement, and manufacturers of instrumentation for tunnel linings. 5 tabs., 9 photos.

  10. Electrokinetic decontamination of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Lomasney, H. [ISOTRON Corp., New Orleans, LA (United States)

    1995-10-01

    The U.S. Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. This report discusses the technology and use at the Oak Ridge k-25 plant.

  11. Structural Materials: 95. Concrete

    International Nuclear Information System (INIS)

    Naus, Dan J.

    2012-01-01

    Nuclear power plant concrete structures and their materials of construction are described, and their operating experience noted. Aging and environmental factors that can affect the durability of the concrete structures are identified. Basic components of a program to manage aging of these structures are identified and described. Application of structural reliability theory to devise uniform risk-based criteria by which existing facilities can be evaluated to achieve a desired performance level when subjected to uncertain demands and to quantify the effects of degradation is outlined. Finally, several areas are identified where additional research is desired.

  12. Improved concretes for corrosion resistance

    Science.gov (United States)

    1997-07-01

    The deterioration of various reinforced concrete bridge components containing conventional black steel reinforcement is the most important problem facing U.S. highway agencies. A major cause of this concrete deterioration (cracking, delamination, and...

  13. Modeling reinforced concrete durability : [summary].

    Science.gov (United States)

    2014-06-01

    Many Florida bridges are built of steel-reinforced concrete. Floridas humid and marine : environments subject steel in these structures : to corrosion once water and salt penetrate the : concrete and contact the steel. Corroded steel : takes up mo...

  14. Advance Organizers: Concret Versus Abstract.

    Science.gov (United States)

    Corkill, Alice J.; And Others

    1988-01-01

    Two experiments examined the relative effects of concrete and abstract advance organizers on students' memory for subsequent prose. Results of the experiments are discussed in terms of the memorability, familiarity, and visualizability of concrete and abstract verbal materials. (JD)

  15. Nonlocal Peridynamic Modeling and Simulation on Crack Propagation in Concrete Structures

    Directory of Open Access Journals (Sweden)

    Dan Huang

    2015-01-01

    Full Text Available An extended peridynamic approach for crack propagation analysis in concrete structures was proposed. In the peridynamic constitutive model, concrete material was described as a series of interacting particles, and the short-range repulsive force and anisotropic behavior of concrete were taken into account in the expression of the interactive bonding force, which was given in terms of classical elastic constants and peridynamic horizon. The damage of material was defined locally at the level of pairwise bond, and the critical stretch of material bond was described as a function of fracture strength in the classical concrete failure theory. The efficiency and accuracy of the proposed model and algorithms were validated by simulating the propagation of mode I and I-II mixed mode cracks in concrete slabs. Furthermore, crack propagation in a double-edge notched concrete beam subjected to four-point load was simulated, in which the experimental observations are captured naturally as a consequence of the solution.

  16. Applications of Foamed Lightweight Concrete

    Directory of Open Access Journals (Sweden)

    Mohd Sari Kamarul Aini

    2017-01-01

    Full Text Available Application of foamed concrete is increasing at present due to high demand on foamed concrete structures with good mechanical and physical properties. This paper discusses on the use of basic raw materials, their characteristics, production process, and their application in foamed lightweight concrete with densities between 300 kg/m3 and 1800 kg/m3. It also discusses the factors that influence the strengths and weaknesses of foamed concrete based on studies that were conducted previously.

  17. TEXTILE TECHNOLOGIES IN CONCRETE ENVIRONMENTS."

    OpenAIRE

    Morrow, Ruth; Belford, Patricia

    2007-01-01

    Girli Concrete is a cross disciplinary funded research project based in the University of Ulster involving a textile designer/ researcher, an architect/ academic and a concrete manufacturing firm.Girli Concrete brings together concrete and textile technologies, testing ideas ofconcrete as textile and textile as structure. It challenges the perception of textiles as only the ‘dressing’ to structure and instead integrates textile technologies into the products of building products. Girli Concre...

  18. Statistical and Detailed Analysis on Fiber Reinforced Self-Compacting Concrete Containing Admixtures- A State of Art of Review

    Science.gov (United States)

    Athiyamaan, V.; Mohan Ganesh, G.

    2017-11-01

    Self-Compacting Concrete is one of the special concretes that have ability to flow and consolidate on its own weight, completely fill the formwork even in the presence of dense reinforcement; whilst maintaining its homogeneity throughout the formwork without any requirement for vibration. Researchers all over the world are developing high performance concrete by adding various Fibers, admixtures in different proportions. Various different kinds Fibers like glass, steel, carbon, Poly propylene and aramid Fibers provide improvement in concrete properties like tensile strength, fatigue characteristic, durability, shrinkage, impact, erosion resistance and serviceability of concrete[6]. It includes fundamental study on fiber reinforced self-compacting concrete with admixtures; its rheological properties, mechanical properties and overview study on design methodology statistical approaches regarding optimizing the concrete performances. The study has been classified into seven basic chapters: introduction, phenomenal study on material properties review on self-compacting concrete, overview on fiber reinforced self-compacting concrete containing admixtures, review on design and analysis of experiment; a statistical approach, summary of existing works on FRSCC and statistical modeling, literature review and, conclusion. It is so eminent to know the resent studies that had been done on polymer based binder materials (fly ash, metakaolin, GGBS, etc.), fiber reinforced concrete and SCC; to do an effective research on fiber reinforced self-compacting concrete containing admixtures. The key aim of the study is to sort-out the research gap and to gain a complete knowledge on polymer based Self compacting fiber reinforced concrete.

  19. Constitutive model for reinforced concrete

    NARCIS (Netherlands)

    Feenstra, P.H.; Borst, de R.

    1995-01-01

    A numerical model is proposed for reinforced-concrete behavior that combines the commonly accepted ideas from modeling plain concrete, reinforcement, and interaction behavior in a consistent manner. The behavior of plain concrete is govern by fracture-energy-level-based formulation both in tension

  20. Porous Concrete and Its Application

    Directory of Open Access Journals (Sweden)

    V. V. Opekunov

    2005-01-01

    Full Text Available Some aspects of resource saving problem in the process of mass construction and operation of heated construction installations are considered in the paper. A special attention is paid to necessary application of porous concrete products in the process of the housing construction. The preference is given to the products made of autoclave cellular concrete and cement hydrophobisized cement perlite concrete.

  1. Concrete produced with recycled aggregates

    Directory of Open Access Journals (Sweden)

    J. J. L. Tenório

    Full Text Available This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW, which were divided into recycled sand (fine and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW. The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.

  2. Structural Concrete, Science into Practice

    NARCIS (Netherlands)

    Bruggeling, A.S.G.

    1987-01-01

    There is a need for a more rational and unified approach to all types of concrete structure, reinforced of prestressed. The first chapter explains in a historical review why the approach of reinforced concrete and that of prestressed concrete have hitherto been very different. In outlining the

  3. Radiodense concretions in maxillary sinus aspergillosis: pathogenesis and the role of CT densitometry

    International Nuclear Information System (INIS)

    Lenglinger, F.X.; Krennmair, G.; Mueller-Schelken, H.; Artmann, W.

    1996-01-01

    The purpose of this study was to investigate by CT the origin of radiodense maxillary sinus concretions and whether CT densitometry is effective in the prediction of maxillary sinus aspergillosis and in the differentiation of the origin of these concretions. In a prospective study in 21 patients with radiodense maxillary sinus concretions detected by radiography, a preoperative CT study of the paranasal sinuses and the concretions was undertaken. Additional scans of the upper alveolar ridge were also performed. Radiological findings were compared with clinical symptoms and with CT findings, especially CT densitometry of the sinus concretions and dental root-filling material. All patients underwent a functional Caldwell-Luc operation; histological and microbiological examinations were performed. Fifteen of the 21 patients (71.4%) with radiodense concretions had a histological and microbiological diagnosis of sinus aspergillosis. The sinus concretions had CT densities higher than 2000 HU (Housfield units) in 15 patients and lower than 2000 HU in 6. Fourteen of 15 patients (93.3%) with concretions ahving CT densities higher than 2000 HU had a postoperative diagnosis of maxillary sinus aspergillosis. The mean CT density of the sinus concretions in patients with maxillary sinus aspergillosis was 2868 HU (range 1870-3070 HU), and in patients without aspergiollosis was 778 HU (range 228-2644 HU). The mean CT density of the dental root-filling material was 2866 HU (range 2156-3070 HU). Paranasal sinus CT with CT densitometry of a sinus concretion has a higher accuracy than standard radiogrpahy and clinical findings in the prediction of maxillary sinus aspergillosis (93.3% vs 71.4%). CT densitometry helps to confirm the dental origin of maxillary sinus concretions and to explain a possible dental pathogenesis of maxillary sinus aspergillosis. (orig.)

  4. Large scale particle image velocimetry with helium filled soap bubbles

    Energy Technology Data Exchange (ETDEWEB)

    Bosbach, Johannes; Kuehn, Matthias; Wagner, Claus [German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Goettingen (Germany)

    2009-03-15

    The application of particle image velocimetry (PIV) to measurement of flows on large scales is a challenging necessity especially for the investigation of convective air flows. Combining helium filled soap bubbles as tracer particles with high power quality switched solid state lasers as light sources allows conducting PIV on scales of the order of several square meters. The technique was applied to mixed convection in a full scale double aisle aircraft cabin mock-up for validation of computational fluid dynamics simulations. (orig.)

  5. Large scale particle image velocimetry with helium filled soap bubbles

    Science.gov (United States)

    Bosbach, Johannes; Kühn, Matthias; Wagner, Claus

    2009-03-01

    The application of Particle Image Velocimetry (PIV) to measurement of flows on large scales is a challenging necessity especially for the investigation of convective air flows. Combining helium filled soap bubbles as tracer particles with high power quality switched solid state lasers as light sources allows conducting PIV on scales of the order of several square meters. The technique was applied to mixed convection in a full scale double aisle aircraft cabin mock-up for validation of Computational Fluid Dynamics simulations.

  6. Double Trouble

    NARCIS (Netherlands)

    Elsaesser, Thomas; Kievit, Robert; Simons, Jan

    1994-01-01

    Double Trouble highlights the career of Dutch scriptwriter and television producer Chiem van Houweninge, well-known for his long-running TV comedy series and as author of episodes for TV detective series. Double Trouble gives Van Houweninge's own views on writing and filming in television prime

  7. Forterra Concrete Products, Inc.

    Science.gov (United States)

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Forterra Concrete Products, Inc., a business located at 511 E. John Carpenter Freeway, Irving, TX, 75062, for alleged violations at its facility located at 23600 W. 40th St

  8. Teaching concrete structures

    DEFF Research Database (Denmark)

    Goltermann, Per

    2014-01-01

    The teaching of concrete structures has been revised and a number of new approaches have been developed, implemented and evaluated. Inductive teaching, E-learning and “patches” have been found to be improvements and may be an inspiration and help for others development of the teaching and learning...

  9. Anisotropic Concrete Compressive Strength

    DEFF Research Database (Denmark)

    Gustenhoff Hansen, Søren; Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2017-01-01

    When the load carrying capacity of existing concrete structures is (re-)assessed it is often based on compressive strength of cores drilled out from the structure. Existing studies show that the core compressive strength is anisotropic; i.e. it depends on whether the cores are drilled parallel...

  10. Continuous Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1996-01-01

    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...

  11. Hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.

    1996-01-01

    As part of the maintenance policy of the Dutch Ministry of Transport, Civil Engineering Division, hydrophobic treatment of concrete was considered as an additional protective measure against penetration of aggressive substances, for instance deicing salts in bridge decks. A set of tests was designed

  12. Concrete longevity overview

    International Nuclear Information System (INIS)

    Chang, W.; Morreale, B.

    1991-01-01

    A number of compact host states and unaffiliated states are currently selecting appropriate disposal technology and construction materials for their planned low-level radioactive waste (LLW) disposal facilities. Concrete is one of the candidate materials under consideration for the construction of LLW disposal facilities because of its strength, durability, abundant availability, and relatively low cost. The LLW disposal facilities must maintain intruder barrier integrity for up to 500 years, without active maintenance after the first 100 years. The ability of concrete to survive for such a long time as a construction material is a critical issue. This report provides a basic understanding of the composition and workings of concrete as a structural material in LLW disposal facilities and a description of degradation factors and state-of-the-art mitigative measures available to preserve the durability and longevity of concrete. Neither the paper nor the report is intended to be a design guidance document, and neither addresses using cement as a waste solidification agent. 5 refs., 1 tab

  13. Fracture Mechanics of Concrete

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    the international workshop on concrete fracture, organised by A Carpinteri, at Torino ... The next question is how to bring the size effect into codes of practice on the ... analysis of the recent collapse of the World Trade Center in New York by Z P ...

  14. Contaminated soil concrete blocks

    NARCIS (Netherlands)

    de Korte, A.C.J.; Brouwers, Jos; Limbachiya, Mukesh C.; Kew, Hsein Y.

    2009-01-01

    According to Dutch law the contaminated soil needs to be remediated or immobilised. The main focus in this article is the design of concrete blocks, containing contaminated soil, that are suitable for large production, financial feasible and meets all technical and environmental requirements. In

  15. Electrical pulses protect concrete

    NARCIS (Netherlands)

    Koleva, D.; Fraaij, A.; Van Kasteren, J.

    2006-01-01

    Even concrete is not as hard as it looks. Sea water, salt on icy roads, and indirectly even carbon dioxide from the air can corrode the steel of the reinforcing bars and so threaten the strength and integrity of a bridge pier, jetty, or viaduct. Dessi Koleva, a chemical engineer from Bulgaria, spent

  16. CONCRETE REACTOR CONTAINMENT

    Energy Technology Data Exchange (ETDEWEB)

    Lumb, Ralph F.; Hall, William F.; Fruchtbaum, Jacob

    1963-06-15

    The results of various leak-rate tests demonstrate the practicality of concrete as primary containment for the maximum credible accident for a research reactor employing plate-type fuel and having a power in excess of one megawatt. Leak-test time was shortened substantially by measuring the relaxation time for overpressure decay, which is a function of leak rate. (auth)

  17. Electroosmotic decontamination of concrete

    International Nuclear Information System (INIS)

    Bostick, W.D.; Bush, S.A.; Marsh, G.C.; Henson, H.M.; Box, W.D.; Morgan, I.L.

    1993-03-01

    A method is described for the electroosmotic decontamination of concrete surfaces, in which an electrical field is used to induce migration of ionic contaminants from porous concrete into an electrolyte solution that may be disposed of as a low-level liquid radioactive waste (LLRW); alternately, the contaminants from the solution can be sorbed onto anion exchange media in order to prevent contaminant buildup in the solution and to minimize the amount of LLRW generated. We have confirmed the removal of uranium (and infer the removal of 99 Tc) from previously contaminated concrete surfaces. In a typical experimental configuration, a stainless steel mesh is placed in an electrolyte solution contained within a diked cell to serve as the negative electrode (cathode) and contaminant collection medium, respectively, and an existing metal penetration (e.g., piping, conduit, or rebar reinforcement within the concrete surface) serves as the positive electrode (anode) to complete the cell. Typically we have achieved 70 to >90% reductions in surface activity by applying 2 )

  18. Polyester polymer concrete overlay.

    Science.gov (United States)

    2013-01-01

    Polyester polymer concrete (PPC) was used in a trial application on a section of pavement that suffers from extensive studded tire wear. The purpose of the trial section is to determine if PPC is a possible repair strategy for this type of pavement d...

  19. Concrete. Connecting Creative Technologists

    NARCIS (Netherlands)

    Bakker, T.P.; Huijboom, N.M.; Koops, R.; Kotterink, B.; Nieuwenhuis, O.A.; Seiffert, L.; Siem, R.; Zee, F.A. van der

    2015-01-01

    Kruisbestuiving tussen de creatieve en high-tech sector biedt enorme kansen, bijvoorbeeld op het gebied van Smart Industry. Desondanks blijven deze kansen in de praktijk vaak onderbenut. In het project 'CONCRETE' heeft TNO op basis van een aantal case studies onderzocht welke succesfactoren tot een

  20. Lightweight self-compacting concrete reinforced with fibres for slab rehabilitation

    International Nuclear Information System (INIS)

    Klein, N. S.; Fuente, A. de la; Aguado, A.; Maso, D.

    2011-01-01

    The slabs of some buildings in Barcelona are formed by unidirectional beams, with a ceramic arch in between, which are filled with broken pottery or construction waste. These structures often present problems such as displacement of the tiles arranged over it due to the lack of stiffness of the filling material. This supposes a risk to the user and could also cause durability problems. In order to rehabilitate it, a lightweight self-compacting concrete reinforced with fibres (HLACF) has been designed to be used as a filling material, improving the stiffness of the structure. This paper presents a structural analysis of a standard case and the results of an experimental campaign. The concrete showed a density of 1665 kg/m3, a slump flow of 605 mm and a compressive strength of 22.3 MPa, at 28 days. These results are in agreement with the requirements, overcoming common lightweight concrete segregation problems. (Author) 24 refs.

  1. QENS investigation of filled rubbers

    CERN Document Server

    Triolo, A; Desmedt, A; Pieper, J K; Lo Celso, F; Triolo, R; Negroni, F; Arrighi, V; Qian, H; Frick, B

    2002-01-01

    The polymer segmental dynamics is investigated in a series of silica-filled rubbers. The presence of inert fillers in polymers greatly affects the mechanical and physical performance of the final materials. For example, silica has been proposed as a reinforcing agent of elastomers in tire production. Results from quasielastic neutron scattering and Dynamic Mechanical Thermal Analysis (DMTA) measurements are presented on styrene-ran-butadiene rubber filled with silica. A clear indication is obtained of the existence of a bimodal dynamics, which can be rationalized in terms of the relaxation of bulk rubber and the much slower relaxation of the rubber adsorbed on the filler surface. (orig.)

  2. Gas-Filled Capillary Model

    International Nuclear Information System (INIS)

    Steinhauer, L. C.; Kimura, W. D.

    2006-01-01

    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration -- Laser Wakefield (STELLA-LW) experiment

  3. Influence of reinforcement mesh configuration for improvement of concrete durability

    Science.gov (United States)

    Pan, Chong-gen; Jin, Wei-liang; Mao, Jiang-hong; Zhang, Hua; Sun, Li-hao; Wei, Dong

    2017-10-01

    Steel bar in concrete structures under harsh environmental conditions, such as chlorine corrosion, seriously affects its service life. Bidirectional electromigration rehabilitation (BIEM) is a new method of repair technology for reinforced concrete structures in such chloride corrosion environments. By applying the BIEM, chloride ions can be removed from the concrete and the migrating corrosion inhibit can be moved to the steel surface. In conventional engineering, the concrete structure is often configured with a multi-layer steel mesh. However, the effect of the BIEM in such structures has not yet been investigated. In this paper, the relevant simulation test is carried out to study the migration law of chloride ions and the migrating corrosion inhibitor in a concrete specimen with complex steel mesh under different energizing modes. The results show that the efficiency of the BIEM increases 50% in both the monolayer steel mesh and the double-layer steel mesh. By using the single-sided BIEM, 87% of the chloride ions are removed from the steel surface. The different step modes can affect the chloride ion removal. The chloride ions within the range of the reinforcement protective cover are easier to be removed than those in the concrete between the two layers of steel mesh. However, the amount of migrating corrosion inhibitor is larger in the latter circumstances.

  4. 111-B Metal Examination Facility Concrete Tanks Characterization Plan

    International Nuclear Information System (INIS)

    Encke, D.B.

    1997-08-01

    The 111-B Metal Examination Facility was a single-story, wood frame 'L'-shaped building built on a concrete floor slab. The facility served as a fuel failure inspection facility. Irradiated fuel pieces were stored and examined in two below grade concrete storage tanks filled with water. The tanks have been filled with grout to stabilize the contamination they contained, and overall dimensions are 5 ft 9 in. (1.5 m 22.8 cm ) wide, 9 ft 1 in. (2.7 m 2.54 cm ) deep, and 10 ft 8 in. (3.0 m 20.32 cm) long, and are estimated to weigh 39 tons. The tanks were used to store and examine failed fuel rods, using water as a radiation shield. The tanks were lined with stainless steel; however, drawings show the liner has been removed from at least one tank (south tank) and was partially filled with grout. The south tank was used to contain the Sample Storage Facility, a multi-level metal storage rack for failed nuclear fuel rods (shown in drawings H-1-2889 and -2890). Both tanks were completely grouted sometime before decontamination and demolition (D ampersand D) of the above ground facility in 1984. The 111-B Metal Examination Facility contained two concrete tanks located below floor level for storage and examination of failed fuel. The tanks were filled with concrete as part of decommissioning the facility prior to 1983 (see Appendix A for description of previous work). Funding for removal and disposal of the tanks ran out before they could be properly disposed

  5. Crumb Rubber-Concrete Panels Under Blast Loads

    Science.gov (United States)

    2010-05-01

    and the samples were labeled. Samples were picked up with an overhead crane and a form spreader connected to two points on the sample, each outside...uniform loading. Shortly after test started 8 to 9 cracks developed within quarter points and 2 cracks developed through pick points where form spreader ...dynamic behaviour of recycled tyre rubber-filled concrete.” Cem. Concr. Res., 32, 1587–1596. Huang, B., Li, G., Pang, S. S., and Eggers, J. (2004

  6. Pouring concrete to form a model LEP dipole yoke

    CERN Multimedia

    1979-01-01

    The magnetic field needed in the LEP dipole magnets was rather low, of a fraction of tesla. This lead to the conception of a novel yoke structure consisting of stacks of 1.5 mm thick low-carbon steel laminations spaced by 4.1 mm with the spaces filled with concrete. For details see LEP-Note 118,1978 and LEP-Note 233,1980. See also 8111529, 8111710X, 7901023X,7908294

  7. Self-compacting concrete (SCC)

    DEFF Research Database (Denmark)

    Geiker, Mette Rica

    2008-01-01

    In many aspects Self-Compacting Concrete (SCC, “Self-Consolidating Concrete” in North America) can be considered the concrete of the future. SCC is a family of tailored concretes with special engineered properties in the fresh state. SCC flows into the formwork and around even complicated...... reinforcement arrangements under its own weight. Thus, SCC is not vibrated like conventional concrete. This drastically improves the working environment during construction, the productivity, and potentially improves the homogeneity and quality of the concrete. In addition SCC provides larger architectural...

  8. Early Property Development in Concrete

    DEFF Research Database (Denmark)

    Normann, Gitte; Munch-Petersen, Christian

    The Freiesleben Maturity function is widely used for planning of execution. We tested if for concrete with and without fly ash. The test showed surprisingly that the maturity function in general is not valid. We found that curing at high temperature gave a significant decrease in strength. Fly ash...... appears to reduce this decrease somewhat. We also examined the resistance against chloride penetration for the different concrete types. The resistance was reduced at high temperatures for concrete without fly ash. For concrete with fly ash, it was the opposite; concrete with fly ash obtained higher...

  9. Estimating Durability of Reinforced Concrete

    Science.gov (United States)

    Varlamov, A. A.; Shapovalov, E. L.; Gavrilov, V. B.

    2017-11-01

    In this article we propose to use the methods of fracture mechanics to evaluate concrete durability. To evaluate concrete crack resistance characteristics of concrete directly in the structure in order to implement the methods of fracture mechanics, we have developed special methods. Various experimental studies have been carried out to determine the crack resistance characteristics and the concrete modulus of elasticity during its operating. A comparison was carried out for the results obtained with the use of the proposed methods and those obtained with the standard methods for determining the concrete crack resistance characteristics.

  10. An historical examination of concrete

    International Nuclear Information System (INIS)

    Mallinson, L.G.

    1986-03-01

    The requirement that concrete in nuclear waste repositories be stable physically and chemically for hundreds, if not thousands, of years has initiated studies of ancient and old concretes. The history of cement and concrete is described. The oldest know concrete, from Yugoslavia, is ca. 7,500 years old. Concrete was used in many ancient civilisations, including those of Egypt, Greece and Rome. Ancient concretes were usually based upon lime, but sometimes gypsum was used. Pure lime concretes hardened by atomospheric carbonation but the Ancients, in particular the Romans, also employed hydraulic limes and discovered pozzolanas to make superior concretes which, upon hardening, contained complex cementitious hydrates including calcium-silicate-hydrate (CSH), the principal binding element in Portland cement concrete. Portland cement was not invented until 1824 or later and consists principally of calcium silicates formed by clinkerisation of a mixture of limestone and clay in carefully measured proportions. The cement sets hydraulically to form, principally, calcium hydroxide and CSH, the latter being an amorphous or semi-amorphous substance of variable composition. The published literature relating to the analysis of old and ancient cements and concretes is reviewed. A suite of samples spanning the history of concrete has been obtained. A variety of physical and chemical techniques have been employed to characterise these samples. (author)

  11. Life Cycle Assessment of Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Sjunnesson, Jeannette

    2005-09-15

    This is an environmental study on concrete that follows the standard protocol of life cycle assessment (LCA). The study is done for two types of concrete, ordinary and frost-resistant concrete, and has an extra focus on the superplasticizers used as admixtures. The utilization phase is not included in this study since the type of construction for which the concrete is used is not defined and the concrete is assumed to be inert during this phase. The results show that it is the production of the raw material and the transports involved in the life cycle of concrete that are the main contributors to the total environmental load. The one single step in the raw material production that has the highest impact is the production of cement. Within the transportation operations the transportation of concrete is the largest contributor, followed by the transportation of the cement. The environmental impact of frost-resistant concrete is between 24-41 % higher than that of ordinary concrete due to its higher content of cement. Superplasticizers contribute with approximately 0.4-10.4 % of the total environmental impact of concrete, the least to the global warming potential (GWP) and the most to the photochemical ozone creation potential (POCP). Also the toxicity of the superplasticizers is investigated and the conclusion is that the low amount of leakage of superplasticizers from concrete leads to a low risk for the environment and for humans.

  12. Filling of charged cylindrical capillaries

    NARCIS (Netherlands)

    Das, Siddhartha; Chanda, Sourayon; Eijkel, J.C.T.; Tas, N.R.; Chakraborty, Suman; Mitra, Sushanta K.

    2014-01-01

    We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because

  13. Space-filling polyhedral sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Haaland, Peter

    2016-06-21

    Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

  14. Modified composite material developed on the basis of no-fines asphalt concrete

    Directory of Open Access Journals (Sweden)

    Mikhasek Andrey

    2017-01-01

    Full Text Available Being a composite material, asphalt concrete is widely used in hydraulic engineering and road construction. The paper proves one of asphalt concrete modification, which includes first creating a skeleton of no-fines concrete and then its washing-down with bituminous materials by a hot procedure, can be successfully used in hydraulic structures Modified composite material based on no-fines asphalt concrete has a harder skeleton because of links from cement stone and has a technological advantage, as through the proposed technology it allows to reduce the cost of filling porous spaces. This technology allows to conclude that concrete aggregate with size fractions of 120 mm or less and frost resistance of 50 cycles and less can be recommended for fastening of slopes.

  15. Concrete - Opalinus clay interaction: in-situ experiment and technique for coring undisturbed interfaces

    International Nuclear Information System (INIS)

    Maeder, U.; Dolder, F.; Jenni, A.; Schwyn, B.; Frieg, B.; Eul, A.

    2012-01-01

    undisturbed samples of the different interfaces with concrete. A first sampling campaign in 2009 used a simple stabilisation technique with a central anchor rod that was glued in before coring. It was impossible to retrieve completely undisturbed samples. A new technique was developed for the drilling campaign during February 2012, and it was successfully applied in all four sampling boreholes carried out, retrieving a total of 150 kg of core and 10 physically and chemically undisturbed interface samples. The technique comprised intersection drilling at 45 deg. inclination and 220 mm OD to within 50 cm of the vertical concrete pile. The base was reamed planar, and templates were installed to drill a circular arrangement of 6 boreholes with 46 mm OD, three at a time. These small boreholes extended across the entire pile (1.4-1.6 m), and anchor rods made of fibre glass and filled with cement were embedded with epoxy resin. A different template was subsequently used to over-core (131 mm OD / 101 mm core DM, double-barrel, acrylic liner) cutting through the reinforcements. Stabilized composite cores of 1.4-1.6 m length could be retrieved in this manner. (authors)

  16. Advantage of using high strength self compacting concrete for precast product

    Science.gov (United States)

    Murdono, Ferryandy; Agustin, Winda; Soeprapto, Gambiro; Sunarso, Mukhlis

    2017-11-01

    According to the development in the world of construction, the need for precast concrete also increases. Now the day there are many products with narrow range reinforcement and difficult dimensions. The ordinary concrete is difficult to pour in a mold with narrow range reinforcement inside without vibrator because the concrete can't fill in the gaps between the bars. SCC (Self Compacting Concrete) is a concrete that precast concrete industry needs to. The using of SCC also supports the green construction through the cement reducing and reducing the use of vibrator that requires not less energy. This research is using EFNARC standard as a condition of admission SCC (filling ability, passing ability, segregation resistance), and performed well against the application of the product by the production of Railway Sleeper without using a vibrator. The results of this study, the LB-2 and LB-3 qualified as SCC and compressive strength is expected that greater than 70 MPa, as well as products quality, is equal to standard and can be mass produced with the efficiency of the price of concrete up to 11%.

  17. Investigation of the existence of self compacting properties in high performance concrete through experimental tests

    Directory of Open Access Journals (Sweden)

    Heitor H. Yoshida

    2007-03-01

    Full Text Available The self compacting concrete is characterized by its capacity to flow inside the formwork filling it exclusively by the force of the gravity with adequate cohesion and viscosity in such a way that segregation does not occur. One of its characteristic is the presence of fines which provide the necessary cohesion,and grains with maximum diameter of 20 mm. This work presents some procedures and experimental methods that make it possible to evaluate self compacting properties of high performance concrete. First, a bibliographical review on the subject was carried out, and later, the equipment used for the accomplishment of the assays were manufactured, in order to verify the properties related to the self compacting concrete: cohesion, viscosity and segregation. As for the work, two concretes were produced with Portland ARI Cement, thick sand, stone powder, sand 0, superplasticizer made of ether-carboxilate chains that differentiate from each other for the presence of active silica in one of them and fly ash in the other. Based on the results, it was verified whether the high performance concrete had self compacting characteristics. In this case, both were considered positive. It was also analyzed the behavior of these concretes in their hardened state by means of the compressive strength test. The Self Compacting Concrete has many advantages such as: reduction in the number of employees, shorter construction period, the non-use of the vibrator and the filling of formworks with high density of… or of complex geometry.

  18. Quality inspection of concrete

    International Nuclear Information System (INIS)

    Mellmann, G.

    1983-01-01

    The testing instruction named in the pertinent standards for concrete vary considerably. They can best be judged through comparing their operating characteristic curves. Here it is noticed for the proof of the solidity of the building, that with the compressive resistances derived from the impact test, method-related severe variations influence the evaluation of the results. In the scope of tests carried out by the Federal Institute for Material Testing, through non destructive, ultrasonic echo return measurements and impact tests as well as through combined evaluation with the aid of a multiple linear regression analysis, it could be proven that a greater confidence level can be achieved and thus a more appropriate judgement of the quality of the concrete of a building is possible. (orig.) [de

  19. Drilling waste makes concrete

    International Nuclear Information System (INIS)

    Rosfjord, A.

    1993-01-01

    The article deals with a method of drilling waste reclamation by utilizing the converted oil-containing cuttings from the North Sea in the concrete production in Norway. The oil content is to be removed in an incineration process by heating the cuttings to about 800 o C. The output capacity from the exhaust gas water cooling system is 7500 kW/hour, and is to be used in different industrial heating processes. The remaining content of pollutants in the cleaned exhaust gas outlet corresponds to the required limits with the exception of SO 2 and HCl. In addition, an exhaust gas washing plant is to be installed in the near future designed for the further reduction of pollutants by 90%. The converted raw materials are used as a supplement for lessening the demand of sand and cement in the production of concrete-made pipes. 1 fig

  20. Reinforced concrete tomography

    International Nuclear Information System (INIS)

    Mariscotti, M.A.J.; Morixe, M.; Tarela, P.A.; Thieberger, P.

    1997-01-01

    In this paper we describe the technique of reinforced concrete tomography, its historical background, recent technological developments and main applications. Gamma radiation sensitive plates are imprinted with radiation going through the concrete sample under study, and then processed to reveal the presence of reinforcement and defects in the material density. The three dimensional reconstruction, or tomography, of the reinforcement out of a single gammagraphy is an original development alternative to conventional methods. Re-bar diameters and positions may be determined with an accuracy of ± 1 mm 0.5-1 cm, respectively. The non-destructive character of this technique makes it particularly attractive in cases of inhabited buildings and diagnoses of balconies. (author) [es

  1. Hypervelocity impact of concrete

    International Nuclear Information System (INIS)

    Watson, A.J.; Anderson, W.F.; Archer, B.

    1982-01-01

    Blocks of concrete and various other materials were impacted by high speed copper jets at the centre of one face, the resulting transient phenomena were measured using ultra high speed photography and various electrical signal transducers. Measurements were made of the jet velocity, penetration rate, crack velocity and initiation time, and strain pulse propagation. Post test measurements were made using electron microscopy, ultra sonics and stereoscopic photography. (orig.) [de

  2. Design of ultra-lightweight concrete: towards monolithic concrete structures

    Directory of Open Access Journals (Sweden)

    Yu Qing Liang

    2014-04-01

    Full Text Available This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K; and moderate mechanical properties, with 28-day compressive strengths of about 10-12 N/mm . This combination of values exceeds, to the researchers’ knowledge, the performance of all other lightweight building materials. Furthermore, the developed lightweight concrete possesses excellent durability properties.

  3. Hard-to-fill vacancies.

    Science.gov (United States)

    Williams, Ruth

    2010-09-29

    Skills for Health has launched a set of resources to help healthcare employers tackle hard-to-fill entry-level vacancies and provide sustainable employment for local unemployed people. The Sector Employability Toolkit aims to reduce recruitment and retention costs for entry-level posts and repare people for employment through pre-job training programmes, and support employers to develop local partnerships to gain access to wider pools of candidates and funding streams.

  4. Operational features of decorative concrete

    Science.gov (United States)

    Bazhenova, Olga; Kotelnikov, Maxim

    2018-03-01

    This article deals with the questions of creation and use of decorative and finishing concrete and mortar. It has been revealed that the most effective artificial rock-imitating stone materials are those made of decorative concrete with the opened internal structure of material. At the same time it is important that the particles of decorative aggregate should be distributed evenly in the concrete volume. It can be reached only at a continuous grain-size analysis of the aggregate from the given rock. The article tackles the necessity of natural stone materials imitation for the cement stone color to correspond to the color of the rock. The possibility of creation of the decorative concrete imitating rocks in the high-speed turbulent mixer is considered. Dependences of durability and frost resistance of the studied concrete on the pore size and character and also parameters characterizing crack resistance of concrete are received.

  5. Concrete workability and fibre content

    OpenAIRE

    Vikan, Hedda

    2007-01-01

    Research report Parameters influencing the workability of fibre concrete and maximum fibre content are given in this state of the art report along with the range of fibre types available on today’s market. The study reveales that new placing techniques and production methods are crucial in order to increase fibre content and concrete strength. Achieving the same mechanical properties as traditionally reinforced concrete will probably also demand changes of the matrix. Finally, reco...

  6. Inspection Strategies for Concrete Bridges

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    1989-01-01

    In this paper an optimal inspection strategy for concrete bridges based on periodic routine and detailed inspections is presented. The failure mode considered is corrosion of the reinforcement due to chlorides. A simple modelling of the corrosion and of the inspection strategy is presented....... The optimal inspection strategy is determined from an optimization problem, where the design variables are time intervals between detailed inspections and the concrete cover. The strategy is illustrated on a simple structure, namely a reinforced concrete beam....

  7. Towards improved modeling of steel-concrete composite wall elements

    International Nuclear Information System (INIS)

    Vecchio, Frank J.; McQuade, Ian

    2011-01-01

    Highlights: → Improved analysis of double skinned steel concrete composite containment walls. → Smeared rotating crack concept applied in formulation of new analytical model. → Model implemented into finite element program; numerically stable and robust. → Models behavior of shear-critical elements with greater ease and improved accuracy. → Accurate assessments of strength, deformation and failure mode of test specimens. - Abstract: The Disturbed Stress Field Model, a smeared rotating crack model for reinforced concrete based on the Modified Compression Field Theory, is adapted to the analysis of double-skin steel-concrete wall elements. The computational model is then incorporated into a two-dimensional nonlinear finite element analysis algorithm. Verification studies are undertaken by modeling various test specimens, including panel elements subject to uniaxial compression, panel elements subjected to in-plane shear, and wall specimens subjected to reversed cyclic lateral displacements. In all cases, the analysis model is found to provide accurate calculations of structural load capacities, pre- and post-peak displacement responses, post-peak ductility, chronology of damage, and ultimate failure mode. Minor deficiencies are found in regards to the accurate portrayal of faceplate buckling and the effects of interfacial slip between the faceplates and the concrete. Other aspects of the modeling procedure that are in need of further research and development are also identified and discussed.

  8. Selection and specification criteria for fills for cut-and-fill mining

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, E. G.

    1980-05-15

    Because of significant differences in placement and loading conditions, the ideal fill material for a cut-and-fill operation has different characteristics to those for a fill for a filled open stoping operation. The differing requirements of the two mining operations must be understood and accounted for in establishing fill selection and specification criteria. Within the paper, aspects of the particular requirements of cut-and-fill mining are analyzed and related to the specific fill tests and properties required. Emphasis is placed upon the role of fill in ground support, though this cannot be isolated from overall fill performance. Where appropriate, test data are introduced and areas requiring continuing research highlighted.

  9. Another Concrete In the Wall

    OpenAIRE

    Meric, Asli Duru

    2015-01-01

    concrete has a memory. It stores the construction sequences. It shows what it is made of and how it is made. The texture of the formwork, the color difference of the pours, and the shadows of the metal ties combine to layer the beauty of concrete. The aim of this study is to explore the instruments of a concrete surface in order to enhance this multi-sensory experience. This study began with the design of a concrete wall and evolved into the design of a single-family home. MARCH

  10. Condition Assessment of PC Tendon Duct Filling by Elastic Wave Velocity Mapping

    Directory of Open Access Journals (Sweden)

    Kit Fook Liu

    2014-01-01

    Full Text Available Imaging techniques are high in demand for modern nondestructive evaluation of large-scale concrete structures. The travel-time tomography (TTT technique, which is based on the principle of mapping the change of propagation velocity of transient elastic waves in a measured object, has found increasing application for assessing in situ concrete structures. The primary aim of this technique is to detect defects that exist in a structure. The TTT technique can offer an effective means for assessing tendon duct filling of prestressed concrete (PC elements. This study is aimed at clarifying some of the issues pertaining to the reliability of the technique for this purpose, such as sensor arrangement, model, meshing, type of tendon sheath, thickness of sheath, and material type as well as the scale of inhomogeneity. The work involved 2D simulations of wave motions, signal processing to extract travel time of waves, and tomography reconstruction computation for velocity mapping of defect in tendon duct.

  11. Build-up Factor Calculation for Ordinary Concrete, Baryte Concrete and Blast-furnace Slugges Concrete as γ Radiation Shielding

    International Nuclear Information System (INIS)

    Isman MT; Elisabeth Supriatni; Tochrul Binowo

    2002-01-01

    Calculation of build up factor ordinary concrete, baryte concrete and blast-furnace sludge concrete have been carried out. The calculations have been carried out by dose rate measurement of Cs 137 source before and after passing through shielding. The investigated variables were concrete type, thickness of concrete and relative possession of concrete. Concrete type variables are ordinary concrete, baryte concrete and blast sludge furnace concrete. The thickness variables were 6, 12, 18, 24, 30 and 36 cm. The relative position variables were dose to the source and close to detector. The result showed that concrete type and position did not have significant effect to build-up factor value, while the concrete thickness (r) and the attenuation coefficient (μ) were influenced to the build-up factor. The higher μr value the higher build-up factor value. (author)

  12. Potential of scrap tire rubber as lightweight aggregate in flowable fill.

    Science.gov (United States)

    Pierce, C E; Blackwell, M C

    2003-01-01

    Flowable fill is a self-leveling and self-compacting material that is rapidly gaining acceptance and application in construction, particularly in transportation and utility earthworks. When mixed with concrete sand, standard flowable fill produces a mass density ranging from 1.8 to 2.3 g/cm(3) (115-145 pcf). Scrap tires can be granulated to produce crumb rubber, which has a granular texture and ranges in size from very fine powder to coarse sand-sized particles. Due to its low specific gravity, crumb rubber can be considered a lightweight aggregate. This paper describes an experimental study on replacing sand with crumb rubber in flowable fill to produce a lightweight material. To assess the technical feasibility of using crumb rubber, the fluid- and hardened-state properties of nine flowable fill mixtures were measured. Mixture proportions were varied to investigate the effects of water-to-cement ratio and crumb rubber content on fill properties. Experimental results indicate that crumb rubber can be successfully used to produce a lightweight flowable fill (1.2-1.6 g/cm(3) [73-98 pcf]) with excavatable 28-day compressive strengths ranging from 269 to 1194 kPa (39-173 psi). Using a lightweight fill reduces the applied stress on underlying soils, thereby reducing the potential for bearing capacity failure and minimizing soil settlement. Based on these results, a crumb rubber-based flowable fill can be used in a substantial number of construction applications, such as bridge abutment fills, trench fills, and foundation support fills.

  13. 30 CFR 817.72 - Disposal of excess spoil: Valley fill/head-of-hollow fills.

    Science.gov (United States)

    2010-07-01

    ... STANDARDS-UNDERGROUND MINING ACTIVITIES § 817.72 Disposal of excess spoil: Valley fill/head-of-hollow fills.... Uncontrolled surface drainage may not be directed over the outslope of the fill. (2) Runoff from areas above the fill and runoff from the surface of the fill shall be diverted into stabilized diversion channels...

  14. Judgement of properties and function of concrete in connection with final disposal of nuclear fuel wastes in rock

    International Nuclear Information System (INIS)

    Bergstroem, S.G.; Fagerlund, G.; Romben, L.

    1977-06-01

    This report deals with the possibility of using concrete in conjuction with the permanent storage of nuclear fuel waste in rock storage facilities. The emphasis has been placed on properties such as strength and tightness and how these may be affected by internal and external causes of destruction during a filling stage of approximately 100 years and during the final storage stage of 1 000 - 100 000 years. It is established that spontaneous structural changes, which lead to a certain increase in porosity, cannot be precluded during the filling stage and uring the final storage stage. It is deemed possible to avoid cracking during the manufacture and during the filling stage if the concrete is kept moist. The risk for cracking during the final storage stage is difficult to assess. Attempts are made to estimate the tightness of aged concrete during the various stages. The tightness during the final storage stage is difficult to assess due to the fact that the scope of the cracking cannot be estimated. Chemical attacks during the filling stage are deemed to be small and can be repaired. The risk for destruction due to radioactive radiation is extremely small. Reinforcement, if any, can be protected during the filling stage on condition that the concrete is kep saturated but all reinforcement will be destroyed during the final storage stage. By way of conclusion, a number of general views on the choice of concrete and work methods are provided. (author)

  15. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    KAUST Repository

    Yoon, Seyoon; Moon, Juhyuk; Bae, Sungchul; Duan, Xiaonan; Giannelis, Emmanuel P.; Monteiro, Paulo M.

    2014-01-01

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had

  16. Technology of hardening fills for mined spaces

    International Nuclear Information System (INIS)

    Simek, P.; Holas, M.; Chyla, A.; Pech, P.

    1985-01-01

    The technology is described of hardening fills for mined spaces of uranium deposits in North Bohemian chalk. A special equipment was developed for the controlled preparation of a hardening mixture. The composition of the fill is determined by the strength of the filled rock, expecially by the standard strength, i.e., the minimal strength of the filling under uniaxial pressure. The said parameter determines the consumption of binding materials and thereby the total costs of the filling. A description is presented of the filling technology, including rabbit tube transport of the mixture and quality control. (Pu)

  17. Utilization of Construction Waste Composite Powder Materials as Cementitious Materials in Small-Scale Prefabricated Concrete

    Directory of Open Access Journals (Sweden)

    Cuizhen Xue

    2016-01-01

    Full Text Available The construction and demolition wastes have increased rapidly due to the prosperity of infrastructure construction. For the sake of effectively reusing construction wastes, this paper studied the potential use of construction waste composite powder material (CWCPM as cementitious materials in small-scale prefabricated concretes. Three types of such concretes, namely, C20, C25, and C30, were selected to investigate the influences of CWCPM on their working performances, mechanical properties, and antipermeability and antifrost performances. Also the effects of CWCPM on the morphology, hydration products, and pore structure characteristics of the cement-based materials were analyzed. The results are encouraging. Although CWCPM slightly decreases the mechanical properties of the C20 concrete and the 7 d compressive strengths of the C25 and C30 concretes, the 28 d compressive strength and the 90 d flexural strength of the C25 and C30 concretes are improved when CWCPM has a dosage less than 30%; CWCPM improves the antipermeability and antifrost performances of the concretes due to its filling and pozzolanic effects; the best improvement is obtained at CWCPM dosage of 30%; CWCPM optimizes cement hydration products, refines concrete pore structure, and gives rise to reasonable pore size distribution, therefore significantly improving the durability of the concretes.

  18. The characterization of cement waste form for final disposal of decommissioned concrete waste

    International Nuclear Information System (INIS)

    Lee, K.W.; Lee, Y.J.; Hwang, D.S.; Moon, J.K.

    2015-01-01

    Since the decommissioning of nuclear plants and facilities, large quantities of slightly contaminated concrete waste have been generated. In Korea, the decontamination and decommissioning of the KRR-1, 2 at the KAERI have been under way. In addition, 83 drums of 200 l, and 41 containers of 4 m 3 of concrete waste were generated. Conditioning of concrete waste is needed for final disposal. Concrete waste is conditioned as follows: mortar using coarse and fine aggregates is filled into a void space after concrete rubble pre-placement into 200 l drums. Thus, this research developed an optimizing mixing ratio of concrete waste, water, and cement, and evaluated the characteristics of a cement waste form to meet the requirements specified in the disposal site specific waste acceptance criteria. The results obtained from compressive strength test, leaching test, and thermal cycling test of cement waste forms conclude that the concrete waste, water, and cement have been suggested to have 75:15:10 as the optimized mixing ratio. In addition, the compressive strength of cement waste form was satisfied, including fine powder up to a maximum 40 wt% in concrete debris waste of about 75%. (authors)

  19. Study on the Utilization of Paper Mill Sludge as Partial Cement Replacement in Concrete

    Directory of Open Access Journals (Sweden)

    Nazar A.M. Md

    2014-03-01

    Full Text Available A major problem arising from the widespread use of forestry biomass and processed timber waste as fuel is related to the production of significant quantities of ash as a by-product from the incineration of such biomasses. A major portion (approximately 70% of the wood waste ash produced is land-filled as a common method of disposal. If the current trend continues with waste products, such as paper mill sludge landfills, a large amount of space would be required by 2020. A revenue study was conducted as a result of investigations into the use of paper mill sludge as recycled materials and additives in concrete mixes for use in construction projects. The study had to provide the assurance that the concrete produced had the correct mechanical strength. Concrete mixes containing paper mill sludge were prepared, and their basic strength characteristics such as the compressive strength, flexural strength, ultra pulse velocity and dynamic modulus elasticity were tested. Four concrete mixes, i.e. a control mix, and a 10%, 20%, and 30% mix of paper mill sludge as cement replacement for concrete were prepared with a DoE mix design by calculating the weight of cement, sand and aggregate. The performance of each concrete specimen was compared with the strength of the control mix. As a result, when the percentage of paper mill sludge in the concrete increased, the strength decreased. Overall, a high correlation was observed between density and strength of the concrete containing paper mill sludge.

  20. Utilization of fly ash and ultrafine GGBS for higher strength foam concrete

    Science.gov (United States)

    Gowri, R.; Anand, K. B.

    2018-02-01

    Foam concrete is a widely accepted construction material, which is popular for diverse construction applications such as, thermal insulation in buildings, lightweight concrete blocks, ground stabilization, void filling etc. Currently, foam concrete is being used for structural applications with a density above 1800kg/m3. This study focuses on evolving mix proportions for foam concrete with a material density in the range of 1200 kg/m3 to 1600 kg/m3, so as to obtain strength ranges that will be sufficient to adopt it as a structural material. Foam concrete is made lighter by adding pre-formed foam of a particular density to the mortar mix. The foaming agent used in this study is Sodium Lauryl Sulphate and in order to densify the foam generated, Sodium hydroxide solution at a normality of one is also added. In this study efforts are made to make it a sustainable construction material by incorporating industrial waste products such as ultrafine GGBS as partial replacement of cement and fly ash for replacement of fine aggregate. The fresh state and hardened state properties of foam concrete at varying proportions of cement, sand, water and additives are evaluated. The proportion of ultrafine GGBS and fly ash in the foam concrete mix are varied aiming at higher compressive strength. Studies on air void-strength relationship of foam concrete are also included in this paper.

  1. Charge balancing fill rate monitor

    International Nuclear Information System (INIS)

    Rothman, J.L.; Blum, E.B.

    1995-01-01

    A fill rate monitor has been developed for the NSLS storage rings to allow machine tuning over a very large dynamic range of beam current. Synchrotron light, focused on a photodiode, produces a signal proportional to the beam current. A charge balancing circuit processes the diode current, creating an output signal proportional to the current injected into the ring. The unit operates linearly over a dynamic range of 120 dB and can resolve pulses of injected beam as small as 1 μA

  2. Characterisation and management of concrete grinding residuals.

    Science.gov (United States)

    Kluge, Matt; Gupta, Nautasha; Watts, Ben; Chadik, Paul A; Ferraro, Christopher; Townsend, Timothy G

    2018-02-01

    Concrete grinding residue is the waste product resulting from the grinding, cutting, and resurfacing of concrete pavement. Potential beneficial applications for concrete grinding residue include use as a soil amendment and as a construction material, including as an additive to Portland cement concrete. Concrete grinding residue exhibits a high pH, and though not hazardous, it is sufficiently elevated that precautions need to be taken around aquatic ecosystems. Best management practices and state regulations focus on reducing the impact on such aquatic environment. Heavy metals are present in concrete grinding residue, but concentrations are of the same magnitude as typically recycled concrete residuals. The chemical composition of concrete grinding residue makes it a useful product for some soil amendment purposes at appropriate land application rates. The presence of unreacted concrete in concrete grinding residue was examined for potential use as partial replacement of cement in new concrete. Testing of Florida concrete grinding residue revealed no dramatic reactivity or improvement in mortar strength.

  3. The influence of using volcanic ash and lime ash as filler on compressive strength in self compacting concrete

    Science.gov (United States)

    Karolina, Rahmi; Panatap Simanjuntak, Murydrischy

    2018-03-01

    Self Compacting Concrete (SCC) is a technology which is developing today in which concrete solidifies by itself without using vibrator. Casting conventional concrete which has a lot of reinforcement bars sometimes finds difficulty in achieving optimal solidity. The method used to solve this problem is by using SCC technology. SCC was made by using filler, volcanic ash, and lime ash as the filling materials so that the concrete became more solid and hollow space could be filled up. The variation of using these two materials was 10%, 15%, 20%, and 25% of the cementitious mass and using 1% of superplasticizer from cementitious material. The supporting testing was done by using the test when the concrete was still fluid and when it was solid. Malleable concrete was tested by using EFNARC 2002 standard in slump flow test, v-funnel test, l-shaped box test, and j-ring test to obtain filling ability and passing ability. In this malleable lime concrete test, there was the decrease, compared with normal SCC concrete without adding volcanic ash and lime ash. Testing was also done in solid concrete in compressive strength, tensile strength, and concrete absorption. The result of the testing showed that the optimum tensile strength in Variation 1, without volcanic ash and lime ash – with 1% of superplasticizer was 39.556 MPa, the optimum tensile strength in Variation 1, without volcanic ash and lime ash- with 1% of super-plasticizer was 3.563 MPa, while the value of optimum absorption which occurred in Variation 5 (25% of volcanic ash + 25% of lime ash + 50% of cement + 1% of superplasticizer) was 1.313%. This was caused by the addition of volcanic ash and lime ash which had high water absorption.

  4. The influence of recycled concrete aggregates in pervious concrete

    Directory of Open Access Journals (Sweden)

    L. M. TAVARES

    Full Text Available The expansion of urban areas under constant changes in the hydrological cycle directly affects the drainage of rainwater. The problems of urban drainage become major engineering problems to be solved in order to avoid negative consequences for local populations. Another urban problem is the excessive production of construction and demolition waste (CDW, in which , even with a increasingly policy of waste management , have been an end up being thrown in inappropriate disposal sites. Alternatively aiming to a minimization of the problems presented, we propose the study of permeable concrete using recycled concrete aggregate. In this study, there were evaluated the performance of concrete by means of permeability, consistency, strength, and interface conditions of the materials . Satisfactory relationships of resistance/permeability of concrete with recycled aggregate in relation to the concrete with natural aggregates was obtained, showing their best potential.

  5. Nuclear radiation and the properties of concrete

    International Nuclear Information System (INIS)

    Kaplan, M.F.

    1983-08-01

    Concrete is used for structures in which the concrete is exposed to nuclear radiation. Exposure to nuclear radiation may affect the properties of concrete. The report mentions the types of nuclear radiation while radiation damage in concrete is discussed. Attention is also given to the effects of neutron and gamma radiation on compressive and tensile strength of concrete. Finally radiation shielding, the attenuation of nuclear radiation and the value of concrete as a shielding material is discussed

  6. Multi objective optimization of foam-filled circular tubes for quasi-static and dynamic responses

    Directory of Open Access Journals (Sweden)

    Fauzan Djamaluddin

    Full Text Available AbstractFuel consumption and safety are currently key aspects in automobile design. The foam-filled thin-walled aluminium tube represents a potentially effective material for use in the automotive industry, due to its energy absorption capability and light weight. Multi-objective crashworthiness design optimization for foam-filled double cylindrical tubes is presented in this paper. The double structures are impacted by a rigid wall simulating quasi-static and dynamic loadings. The optimal parameters under consideration are the minimum peak crushing force and maximum specific energy absorption, using the non-dominated sorting genetic algorithm-II (NSGA-II technique. Radial basis functions (RBF and D-Optimal are adopted to determine the more complex crashworthiness functional objectives. The comparison is performed by finite element analysis of the impact crashworthiness characteristics in tubes under static and dynamic loads. Finally, the optimum crashworthiness performance of empty and foam-filled double tubes is investigated and compared to the traditional single foam-filled tube. The results indicate that the foam-filled double aluminium circular tube can be recommended for crashworthy structures.

  7. Bio-inspired dental fillings

    Science.gov (United States)

    Deyhle, Hans; Bunk, Oliver; Buser, Stefan; Krastl, Gabriel; Zitzmann, Nicola U.; Ilgenstein, Bernd; Beckmann, Felix; Pfeiffer, Franz; Weiger, Roland; Müller, Bert

    2009-08-01

    Human teeth are anisotropic composites. Dentin as the core material of the tooth consists of nanometer-sized calcium phosphate crystallites embedded in collagen fiber networks. It shows its anisotropy on the micrometer scale by its well-oriented microtubules. The detailed three-dimensional nanostructure of the hard tissues namely dentin and enamel, however, is not understood, although numerous studies on the anisotropic mechanical properties have been performed and evaluated to explain the tooth function including the enamel-dentin junction acting as effective crack barrier. Small angle X-ray scattering (SAXS) with a spatial resolution in the 10 μm range allows determining the size and orientation of the constituents on the nanometer scale with reasonable precision. So far, only some dental materials, i.e. the fiber reinforced posts exhibit anisotropic properties related to the micrometer-size glass fibers. Dental fillings, composed of nanostructures oriented similar to the natural hard tissues of teeth, however, do not exist at all. The current X-ray-based investigations of extracted human teeth provide evidence for oriented micro- and nanostructures in dentin and enamel. These fundamental quantitative findings result in profound knowledge to develop biologically inspired dental fillings with superior resistance to thermal and mechanical shocks.

  8. The concrete canister program

    International Nuclear Information System (INIS)

    Ohta, M.M.

    1978-02-01

    In the spring of 1974, WNRE began development and demonstration of a dry storage concept, called the concrete canister, as a possible alternative to storage of irradiated CANDU fuel in water pools. The canister is a thick-walled concrete monolith containing baskets of fuel in the dry state. The decay heat from the fuel is dissipated to the environment by natural heat transfer. Four canisters were designed and constructed. Two canisters containing electric heaters have been subjected to heat loads of 2.5 times the design, ramp heat-load cycling, and simulated weathering tests. The other two canisters were loaded with irradiated fuel, one containing fuel bundles of uniform decay heat and the other containing bundles of non-uniform decay heat in a non-symmetrical radial and axial array. The collected data were used to verify the analytical tools for prediction of effectiveness of heat transfer and radiation shielding and to verify the design of the basket and canisters. The demonstration canisters have shown that this concept is a viable alternative to water pools for the storage of irradiated CANDU fuel. (author)

  9. Simulation of the Test Method "L-Box" for Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm; Szabo, Peter; Geiker, Mette Rica

    2004-01-01

    Both filling and passing ability are important properties to be considered for self-compacting concrete. This paper presents simulations of the L-box test and corresponding experiments. The assumption of a continuum mechanical approach, where the fluid rheology is described by the Bingham model...

  10. The Concrete and Pavement Challenge

    Science.gov (United States)

    Roman, Harry T.

    2012-01-01

    The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

  11. Revised Rules for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.

    This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

  12. Proportioning of light weight concrete

    DEFF Research Database (Denmark)

    Palmus, Lars

    1996-01-01

    Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory......Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory...

  13. Fatigue of Concrete Armour Units

    DEFF Research Database (Denmark)

    Sørensen, N. B.; Burcharth, H. F.; Liu, Z.

    1995-01-01

    In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed.......In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed....

  14. Concrete for γ radiation shielding

    International Nuclear Information System (INIS)

    Azevedo e Souza, A.C. de; Rogers, John Douglas

    1980-01-01

    The attenuation characteristics of γ radiation in concrete slabs, considering their mechanical resistence and densities were determined. One heavy concrete which was used, was prepared using as additives iron ore and Fe 2 O 3 pellets in various grain sizes. Fortran programs were used for analysing data and determining the absorption coefficients and attenuation factors. (Author) [pt

  15. Radiographic testing in concrete structures

    International Nuclear Information System (INIS)

    Oliveira, D. de

    1987-01-01

    The radiographic testing done in concrete structures is used to analyse the homogeneity, position and corrosion of armatures and to detect discontinuity in the concrete such as: gaps, cracks and segregations. This work develops a Image quality Indicator (IQI) with an adequated sensibility to detect discontinuites based on BS4408 norm. (E.G.) [pt

  16. Wood and concrete polymer composites

    International Nuclear Information System (INIS)

    Singer, K.

    1974-01-01

    There are several ways to prepare and use wood and concrete polymer composites. The most important improvements in the case of concrete polymer composites are obtained for compressive and tensile strengths. The progress in this field in United States and other countries is discussed in this rview. (M.S.)

  17. Concrete for. gamma. radiation shielding

    Energy Technology Data Exchange (ETDEWEB)

    de Azevedo e Souza, A.C. (Rio de Janeiro Univ. (Brazil). Inst. de Quimica); Rogers, J D [Rio de Janeiro Univ. (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1980-06-01

    The attenuation characteristics of ..gamma.. radiation in concrete slabs, considering their mechanical resistence and densities were determined. One heavy concrete which was used, was prepared using as additives iron ore and Fe/sub 2/ O/sub 3/ pellets in various grain sizes. Fortran programs were used for analysing data and determining the absorption coefficients and attenuation factors.

  18. Concrete shielding exterior to iron

    International Nuclear Information System (INIS)

    Yurista, P.; Cossairt, D.

    1983-08-01

    A rule of thumb at Fermilab has been to use 3 feet of concrete exterior to iron shielding. A recent design of a shield with a severe dimensional constraint has prompted a re-evaluation of this rule of thumb and has led to the following calculations of the concrete thickness required to nullify this problem. 4 references, 4 figures

  19. Urban heritage, building maintenance : Concrete

    NARCIS (Netherlands)

    Verhoef, L.G.W.

    1999-01-01

    Concrete as a conglomerate of sand, stone and a binder, is a very old material indeed. In the Roman period earth from Puozzoli, together with lime and water could bind the sand and the stones to form a conglomerate that has an affmity to our modem concrete. Later, in the more northem areas of

  20. Concrete Operations and Attentional Capacity.

    Science.gov (United States)

    Chapman, Michael; Lindenberger, Ulman

    1989-01-01

    To test predictions regarding the attentional capacity requirements of Piaget's stage of concrete operations, a battery of concrete operational tasks and two measures of attentional capacity were administered to 120 first-, second-, and third-graders. Findings concern class inclusion, transitivity of length and weight, and multiplication of…

  1. Shear reinforced beams in autoclaved aerated concrete

    DEFF Research Database (Denmark)

    Cornelius, Thomas

    2010-01-01

    Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different combinat....... Codes for designing prefabricated reinforced components of aircrete structures have adopted these recently developed approaches.......Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different...

  2. FINITE ELEMENT ANALYSIS OF CONCRETE FILLER INFLUENCE ON DYNAMIC RIGIDITY OF HEAVY MACHINE TOOL PORTAL

    Directory of Open Access Journals (Sweden)

    Yu. V. Vasilevich

    2016-01-01

    Full Text Available Virtual testing of portal machine tool has been carried out with the help of finite elements method (FEM. Static, modal and harmonic analyses have been made for a heavy planer. The paper reveals influence of concrete filler on machine tool dynamic flexibility. A peculiar feature of the simulation is concrete filling of a high-level transverse beam. Such approach oes look a typical one for machine-tool industry. Concrete has been considered as generalized material in two variants. It has been established that concrete application provides approximately 3-fold increase in machine tool rigidity per each coordinate. In this regard it is necessary to arrange closure of rigidity contour by filling all the cavities inside of the portal. Modal FEA makes it possible to determine that concrete increases comparatively weakly (1.3–1.4-fold frequencies of resonance modes. Frequency of the lowest mode rises only from 30.25 to 42.86 Hz. The following most active whole-machine eigenmodes have been revealed in the paper: “Portal pecking”, “Parallelogram” and “Traverse pecking”. In order to restrain the last mode it is necessary to carry out concrete filling of the traverse, in particular. Frequency-response characteristics and curves of dynamic rigidity for a spindle have been plotted for 0–150 Hz interval while using harmonic FEM. It has been determined that concrete increases dynamic machine tool rigidity by 2.5–3.5-fold. The effect is obtained even in the case when weakly damping concrete (2 % is used. This is due to distribution of vibrational energy flow along concrete and along cast iron as well. Thus energy density and vibration amplitudes must decrease. The paper shows acceptability for internal reinforcement of high-level machine tool parts (for example, portal traverses and fillers are applied for this purpose. Traverse weighting is compensated by additional torsional, shear and bending rigidity. The machine tool obtains the

  3. Vertical Scan-Conversion for Filling Purposes

    OpenAIRE

    Hersch, R. D.

    1988-01-01

    Conventional scan-conversion algorithms were developed independently of filling algorithms. They cause many problems, when used for filling purposes. However, today's raster printers and plotters require extended use of filling, especially for the generation of typographic characters and graphic line art. A new scan-conversion algorithm, called vertical scan-conversion has been specifically designed to meet the requirements of parity scan line fill algorithms. Vertical scan-conversion ensures...

  4. Strength and related properties of concrete: A quantitative approach

    Energy Technology Data Exchange (ETDEWEB)

    Popovics, S. [Drexel Univ., Philadelphia, PA (United States). Dept. of Civil Engineering

    1998-12-31

    The science and technology of concrete have been based almost exclusively on empirical knowledge. The description of concrete properties and behavior was therefore by necessity mostly of qualitative nature. The author, a recognized expert in the field, has attempted to present a very special state-of-the-art report in such a way that it can point in the direction of rationalizing the theory. The overall goal can be stated as follows: Given the properties of the various components of concrete, the mix proportions, etc., can one compute important properties, such as strength, of the end product? The quantitative approach mentioned in the subtitle is meant to assist in achieving this objective. It is so ambitious an undertaking that it could not succeed. In fact, judging from the preface, it can be assumed that the author himself did not expect to succeed, but rather be content with setting the stage for other researchers to take off from. The book fills an important void in the specialized concrete literature. The lack of rational relationships in this empirical science makes it very difficult to teach to students and to present it in an interesting manner. Yet, it is not written with the undergraduate student in mind. The enormous collection of data from the literature makes it a treasure trove for researchers and, to a lesser extent, for practicing engineers. For simple relationships such as those between cube strength and cylinder strength, this is the book to look for. The 75-page bibliography is impressive. The intentional limitation of the book`s scope to concrete limits its applicability, especially since it is now being recognized that properties of concrete other than strength may be equally if not more important than strength.

  5. Novel techniques for concrete curing

    DEFF Research Database (Denmark)

    Kovler, Konstantin; Jensen, Ole Mejlhede

    2005-01-01

    It is known that some high-strength/high-performance concretes (HSC/HPC) are prone to cracking at an early age unless special precautions are taken. The paper deals with the methods of curing as one of the main strategies to ensure good performance of concrete. Curing by both external (conventional......) and internal methods is reviewed and analyzed, among other methods of mitigating shrinkage and cracking of concrete. The focus is on the mitigation of autogenous shrinkage of low water to binder ratio (w/b) concrete by means of internal curing. The concepts of internal curing are based on using lightweight...... aggregate, superabsorbent polymers or water-soluble chemicals, which reduce water evaporation (so called "internal sealing"). These concepts have been intensively researched in the 90s, but still are not widespread among contractors and concrete suppliers. The differences between conventional methods...

  6. Basic principles of concrete structures

    CERN Document Server

    Gu, Xianglin; Zhou, Yong

    2016-01-01

    Based on the latest version of designing codes both for buildings and bridges (GB50010-2010 and JTG D62-2004), this book starts from steel and concrete materials, whose properties are very important to the mechanical behavior of concrete structural members. Step by step, analysis of reinforced and prestressed concrete members under basic loading types (tension, compression, flexure, shearing and torsion) and environmental actions are introduced. The characteristic of the book that distinguishes it from other textbooks on concrete structures is that more emphasis has been laid on the basic theories of reinforced concrete and the application of the basic theories in design of new structures and analysis of existing structures. Examples and problems in each chapter are carefully designed to cover every important knowledge point. As a basic course for undergraduates majoring in civil engineering, this course is different from either the previously learnt mechanics courses or the design courses to be learnt. Compa...

  7. Sodium concrete reaction - Structural considerations

    International Nuclear Information System (INIS)

    Ferskakis, G.N.

    1984-01-01

    An overview of the sodium concrete reaction phenomenon, with emphasis on structural considerations, is presented. Available test results for limestone, basalt, and magnetite concrete with various test article configurations are reviewed. Generally, tests indicate reaction is self limiting before all sodium is used. Uncertainties, however, concerning the mechanism for penetration of sodium into concrete have resulted in different theories about a reaction model. Structural behavior may be significant in the progression of the reaction due to thermal-structuralchemical interactions involving tensile cracking, compressive crushing, or general deterioration of concrete and the exposure of fresh concrete surfaces to react with sodium. Structural behavior of test articles and potential factors that could enhance the progression of the reaction are discussed

  8. Concrete poetry in three languages

    Directory of Open Access Journals (Sweden)

    Aleksandra Kremer

    2013-01-01

    Full Text Available This paper analyzes different paths of the development of both the movement and the notion of concrete poetry in three linguistic regions. The German-language konkrete Dichtung turns out to usually denote the original, historical shape of the movement, which was partly created in German- speaking countries and which has been treated as a literary phenomenon. The Englishlanguage term concrete poetry is a much broader category which also encompasses visual poetry and avant-garde texts that are distant from the sources of concretism in its early form. The Polish understanding of ‘poezja konkretna’ [concrete poetry] was influenced by both German- and English- language books and by the movement’s regional version, which appeared in Poland as late as in the 1970s. The selected linguistic areas allowed the author to show three basic ways of thinking about concretism, i.e. about its initial, international, and regional versions.

  9. Concrete-Opalinus clay interaction

    International Nuclear Information System (INIS)

    Jenni, A.; Maeder, U.; Lerouge, C.; Gaboreau, S.; Schwyn, B.

    2012-01-01

    Document available in extended abstract form only. Designs for deep geologic disposal of radioactive waste foresee cementitious materials as structural elements, backfill or waste matrix. Therefore, studies of interactions between cement and all other materials involved are important. Interactions are mostly driven by chemical gradients in pore water and might lead to mineralogical alterations in the barrier system, which in turn influence properties like swelling pressure, permeability, or specific retention in case of clay materials. Existing laboratory and in-situ studies using clay-stone revealed significant alteration in both cement and clay-stone. Phase dissolution, precipitation, and carbonation, were found to cause an overall porosity increase in the cement with a possible decrease close to the interface, and clogging in the clay-stone [2]. Most of the work was done on cement pastes rather than concretes to avoid analytical complications caused by aggregates, and the scale of investigation was chosen in the range of centimetres rather than micrometers. The Cement-Clay Interaction (CI) experiment at the Mont Terri Underground Laboratory (St. Ursanne, Switzerland) aims at replicating some of the processes at interfaces to be expected.For this purpose, two vertical cylindrical boreholes (384 mm diameter, up to 10 m length) in Opalinus Clay (OPA) were filled with layers of three different concretes and bentonite. The concrete formulations are based on common aggregate content and grain size distributions, combined with three different cements: Portland cement (OPC), ESDRED cement especially designed for repository applications (40% of cement substituted with silica fume), and low alkali cement (LAC, containing slag and nano-silica).In this study, we present a characterisation of the three concrete-OPA interfaces after two years of alteration and deduce possible mechanisms. Backscattered electron (BE) imaging and energy dispersive spectrum (EDX) element mapping

  10. 7 CFR 58.923 - Filling containers.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Filling containers. 58.923 Section 58.923 Agriculture... Procedures § 58.923 Filling containers. (a) The filling of small containers with product shall be done in a sanitary manner. The containers shall not contaminate or detract from the quality of the product in any way...

  11. Nuclear Power Plant Concrete Structures

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Prabir [International Atomic Energy Agency (IAEA); Labbe, Pierre [Electricity of France (EDF); Naus, Dan [Oak Ridge National Laboratory (ORNL)

    2013-01-01

    A nuclear power plant (NPP) involves complex engineering structures that are significant items of the structures, systems and components (SSC) important to the safe and reliable operation of the NPP. Concrete is the commonly used civil engineering construction material in the nuclear industry because of a number of advantageous properties. The NPP concrete structures underwent a great degree of evolution, since the commissioning of first NPP in early 1960. The increasing concern with time related to safety of the public and environment, and degradation of concrete structures due to ageing related phenomena are the driving forces for such evolution. The concrete technology underwent rapid development with the advent of chemical admixtures of plasticizer/super plasticizer category as well as viscosity modifiers and mineral admixtures like fly ash and silica fume. Application of high performance concrete (HPC) developed with chemical and mineral admixtures has been witnessed in the construction of NPP structures. Along with the beneficial effect, the use of admixtures in concrete has posed a number of challenges as well in design and construction. This along with the prospect of continuing operation beyond design life, especially after 60 years, the impact of extreme natural events ( as in the case of Fukushima NPP accident) and human induced events (e.g. commercial aircraft crash like the event of September 11th 2001) has led to further development in the area of NPP concrete structures. The present paper aims at providing an account of evolution of NPP concrete structures in last two decades by summarizing the development in the areas of concrete technology, design methodology and construction techniques, maintenance and ageing management of concrete structures.

  12. POROUS STRUCTURE OF ROAD CONCRETE

    Directory of Open Access Journals (Sweden)

    M. K. Pshembaev

    2016-01-01

    Full Text Available Having a great number of concrete structure classifications it is recommended to specify the following three principal types: microstructure – cement stone structure; mesostructure – structure of cement-sand mortar in concrete; macrostucture – two-component system that consists of mortar and coarse aggregate. Every mentioned-above structure has its own specific features which are related to the conditions of their formation. Thus, microstructure of cement stone can be characterized by such structural components as crystal intergrowth, tobermorite gel, incompletely hydrated cement grains and porous space. The most important technological factors that influence on formation of cement stone microstructure are chemical and mineralogical cement composition, its grinding fineness, water-cement ratio and curing condition. Specific cement stone microstructure is formed due to interrelation of these factors. Cement stone is a capillary-porous body that consists of various solid phases represented predominantly by sub-microcrystals of colloidal dispersion. The sub-microcrystals are able adsorptively, osmotically and structurally to withhold (to bind some amount of moisture. Protection of road concrete as a capillary-porous body is considered as one of the topical issues. The problem is solved with the help of primary and secondary protection methods. Methods of primary protection are used at the stage of designing, preparation and placing of concrete. Methods of secondary protection are applied at the operational stage of road concrete pavement. The paper considers structures of concrete solid phase and characteristics of its porous space. Causes of pore initiation, their shapes, dimensions and arrangement in the concrete are presented in the paper. The highest hazard for road concrete lies in penetration of aggressive liquid in it and moisture transfer in the cured concrete. Water permeability of concrete characterizes its filtration factor which

  13. Structures-of-the-Whole: Is There Any Glue to Hold the Concrete-Operational "Stage" Together?

    Science.gov (United States)

    Brainerd, Charles J.

    Studies concerned with the synchronous emergence prediction of Piaget's structures-of-the-whole principle are discussed in conjunction with three groups of concrete-operational skills: (1) transitivity/conservation/class inclusion; (2) double classification/double seriation; and (3) ordinal, cardinal, and natural number concepts. Findings show…

  14. Properties of concretes produced with waste concrete aggregate

    International Nuclear Information System (INIS)

    Topcu, Ilker Bekir; Sengel, Selim

    2004-01-01

    An environmentally friendly approach to the disposal of waste materials, a difficult issue to cope with in today's world, would only be possible through a useful recycling process. For this reason, we suggest that clearing the debris from destroyed buildings in such a way as to obtain waste concrete aggregates (WCA) to be reused in concrete production could well be a partial solution to environmental pollution. For this study, the physical and mechanical properties along with their freeze-thaw durability of concrete produced with WCAs were investigated and test results presented. While experimenting with fresh and hardened concrete, mixtures containing recycled concrete aggregates in amounts of 30%, 50%, 70%, and 100% were prepared. Afterward, these mixtures underwent freeze-thaw cycles. As a result, we found out that C16-quality concrete could be produced using less then 30% C14-quality WCA. Moreover, it was observed that the unit weight, workability, and durability of the concretes produced through WCA decreased in inverse proportion to their endurance for freeze-thaw cycle

  15. Double Chooz

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Christian [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

    2006-05-15

    The goal of the Double Chooz reactor neutrino experiment is to search for the neutrino mixing parameter {theta}{sub 13}. Double Chooz will use two identical detectors at 150 m and 1.05 km distance from the reactor cores. The near detector is used to monitor the reactor {nu}-bar {sub e} flux while the second is dedicated to the search for a deviation from the expected (1/distance){sup 2} behavior. This two detector concept will allow a relative normalization systematic error of ca. 0.6 %. The expected sensitivity for sin{sup 2}2{theta}{sub 13} is then in the range 0.02 - 0.03 after three years of data taking. The antineutrinos will be detected in a liquid scintillator through the capture on protons followed by a gamma cascade, produced by the neutron capture on Gd.

  16. Double supergeometry

    Energy Technology Data Exchange (ETDEWEB)

    Cederwall, Martin [Division for Theoretical Physics, Department of Physics, Chalmers University of Technology,SE 412 96 Gothenburg (Sweden)

    2016-06-27

    A geometry of superspace corresponding to double field theory is developed, with type I I supergravity in D=10 as the main example. The formalism is based on an orthosymplectic extension OSp(d,d|2s) of the continuous T-duality group. Covariance under generalised super-diffeomorphisms is manifest. Ordinary superspace is obtained as a solution of the orthosymplectic section condition. A systematic study of curved superspace Bianchi identities is performed, and a relation to a double pure spinor superfield cohomology is established. A Ramond-Ramond superfield is constructed as an infinite-dimensional orthosymplectic spinor. Such objects in minimal orbits under the OSp supergroup (“pure spinors”) define super-sections.

  17. Double ambidexterity

    DEFF Research Database (Denmark)

    Kaulio, Matti; Thorén, Kent; Rohrbeck, René

    2017-01-01

    We leverage the business model innovation and ambidexterity literature to investigate a contradictory case, the Swedish-Finnish Telecom operator TeliaSonera. Despite being challenged by three major disruptions, the company not only still exists but also enjoys remarkably good financial performance....... Building on extant archival data and interviews, we carefully identify and map 26 organizational responses during 1992–2016. We find that the firm has overcome three critical phases by experimenting and pioneering with portfolios of business models and/or technological innovations. We describe...... this behaviour as double ambidexterity. We use an in-depth case study to conceptualize double ambidexterity and discuss its impact on the business's survival and enduring success....

  18. SIMULATION MODELS OF RESISTANCE TO CONCRETE MOVEMENT IN THE CONCRETE CONVEYING PIPE OF THE AUTOCONCRETE PUMP

    OpenAIRE

    Anofriev, P. G.

    2015-01-01

    Purpose. In modern construction the placing of concrete is often performed using distribution equipment of concrete pumps. Increase of productivity and quality of this construction work requires improvement of both concrete pumps and their tooling. The concrete pumps tooling consists of standardized concrete conveying pipes and connector bends radius of up to 2 m. A promising direction of tooling improvement is the reduce of resistance to movement of the concrete in the concrete conveying pip...

  19. Lightweight self-compacting concrete reinforced with fibres for slab rehabilitation; Hormigon ligero autocompactante con fibras para rehabilitacion de forjados

    Energy Technology Data Exchange (ETDEWEB)

    Klein, N. S.; Fuente, A. de la; Aguado, A.; Maso, D.

    2011-07-01

    The slabs of some buildings in Barcelona are formed by unidirectional beams, with a ceramic arch in between, which are filled with broken pottery or construction waste. These structures often present problems such as displacement of the tiles arranged over it due to the lack of stiffness of the filling material. This supposes a risk to the user and could also cause durability problems. In order to rehabilitate it, a lightweight self-compacting concrete reinforced with fibres (HLACF) has been designed to be used as a filling material, improving the stiffness of the structure. This paper presents a structural analysis of a standard case and the results of an experimental campaign. The concrete showed a density of 1665 kg/m3, a slump flow of 605 mm and a compressive strength of 22.3 MPa, at 28 days. These results are in agreement with the requirements, overcoming common lightweight concrete segregation problems. (Author) 24 refs.

  20. ASSESSMENT OF RELEASE RATES FOR RADIONUCLIDES IN ACTIVATED CONCRETE.

    Energy Technology Data Exchange (ETDEWEB)

    SULLIVAN,T.M.

    2003-08-23

    The Maine Yankee (MY) nuclear power plant is undergoing the process of decontamination and decommissioning (D&D). Part of the process requires analyses that demonstrate that any radioactivity that remains after D&D will not cause exposure to radioactive contaminants to exceed acceptable limits. This requires knowledge of the distribution of radionuclides in the remaining material and their potential release mechanisms from the material to the contacting groundwater. In this study the concern involves radionuclide contamination in activated concrete in the ICI Sump below the containment building. Figures 1-3 are schematic representations of the ICI Sump. Figure 2 and 3 contain the relevant dimensions needed for the analysis. The key features of Figures 2 and 3 are the 3/8-inch carbon steel liner that isolates the activated concrete from the pit and the concrete wall, which is between 7 feet and 7 feet 2 inches thick. During operations, a small neutron flux from the reactor activated the carbon steel liner and the concrete outside the liner. Current MY plans call for filling the ICI sump with compacted sand.

  1. Waste-Based Pervious Concrete for Climate-Resilient Pavements.

    Science.gov (United States)

    Ho, Hsin-Lung; Huang, Ran; Hwang, Lih-Chuan; Lin, Wei-Ting; Hsu, Hui-Mi

    2018-05-27

    For the sake of environmental protection and circular economy, cement reduction and cement substitutes have become popular research topics, and the application of green materials has become an important issue in the development of building materials. This study developed green pervious concrete using water-quenched blast-furnace slag (BFS) and co-fired fly ash (CFFA) to replace cement. The objectives of this study were to gauge the feasibility of using a non-cement binder in pervious concrete and identify the optimal binder mix design in terms of compressive strength, permeability, and durability. For filled percentage of voids by cement paste (FPVs) of 70%, 80%, and 90%, which mixed with CFFA and BFS as the binder (40 + 60%, 50 + 50%, and 60 + 40%) to create pervious concrete with no cement. The results indicate that the complete (100%) replacement of cement with CFFA and BFS with no alkaline activator could induce hydration, setting, and hardening. After a curing period of 28 days, the compressive strength with different FPVs could reach approximately 90% that of the control cement specimens. The cementless pervious concrete specimens with BFS:CFFA = 7:3 and FPV = 90% presented better engineering properties and permeability.

  2. A Novel Passive Wireless Sensor for Concrete Humidity Monitoring.

    Science.gov (United States)

    Zhou, Shuangxi; Deng, Fangming; Yu, Lehua; Li, Bing; Wu, Xiang; Yin, Baiqiang

    2016-09-20

    This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. The sensor interface converts the humidity capacitance into a digital signal in the frequency domain. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture. The clock generator employs a novel structure to reduce the internal voltage swing. The measurement results show that our proposed wireless humidity can achieve a high linearity with a normalized sensitivity of 0.55% %RH at 20 °C. Despite the high losses of concrete, the proposed wireless humidity sensor achieves reliable communication performances in passive mode. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at the depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods.

  3. Reaction products of densified silica fume agglomerates in concrete

    International Nuclear Information System (INIS)

    Diamond, Sidney; Sahu, Sadananda; Thaulow, Niels

    2004-01-01

    Most silica fume currently used in concrete is in the dry densified form and consists of agglomerates of sizes between 10 μm and several millimeters. Many of these agglomerates may break down only partially in normal concrete mixing. Examination of various mature silica-fume-bearing concretes using backscatter mode scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis shows that such agglomerates have reacted in situ and given rise to recognizable types of reaction products filling the space within the original outline of the agglomerate. One type is 'quiescent', and usually shows no evidence of volume instability. EDX spectra indicate that the product formed within such grains is C-S-H of very low Ca/Si ratio, with modest alkali contents. Other silica fume agglomerates may undergo a distinct alkali-silica-type reaction (ASR), with the reaction product found within the original outline of the agglomerate having significantly less calcium and usually much higher alkali contents than the quiescent type. Such reacted agglomerates show evidence of local expansion, shrinkage cracking (on drying), and other features common to ASR. Both types may be found within the same concrete, sometimes in close proximity. It further appears that exposure to seawater may convert previously formed reaction products of silica fume agglomerates to magnesium silicate hydrates

  4. A Novel Passive Wireless Sensor for Concrete Humidity Monitoring

    Directory of Open Access Journals (Sweden)

    Shuangxi Zhou

    2016-09-01

    Full Text Available This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF Radio Frequency Identification (RFID technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. The sensor interface converts the humidity capacitance into a digital signal in the frequency domain. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture. The clock generator employs a novel structure to reduce the internal voltage swing. The measurement results show that our proposed wireless humidity can achieve a high linearity with a normalized sensitivity of 0.55% %RH at 20 °C. Despite the high losses of concrete, the proposed wireless humidity sensor achieves reliable communication performances in passive mode. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at the depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods.

  5. Experimental and Numerical Study of FRP Encased Composite Concrete Columns

    Directory of Open Access Journals (Sweden)

    Mohsen Ishaghian

    2017-02-01

    Full Text Available A new type of composite column is presented and assessed through experimental testing and numerical modeling. The objective of this research is to investigate design options for a composite column without the use of ferrous materials. This is to avoid the current problem of deterioration of concrete due to expansion of rusting reinforcement members. Such a target can be achieved by replacing the steel reinforcement of concrete columns with pultruded I-shape glass FRP structural sections. The composite column utilizes a glass FRP tube that surrounds a pultruded I-section glass FRP, which is subsequently filled with concrete. The GFRP tube acts as a stay-in-place form in addition to providing confinement to the concrete. A total of four composite columns were tested under monotonic axial loading. The experimental ultimate capacity of each of the tested composite column was compared to the predicted numerical capacity using ANSYS program. The comparison showed that the predicted numerical values were in good agreement with the experimental ones.

  6. A Novel Passive Wireless Sensor for Concrete Humidity Monitoring

    Science.gov (United States)

    Zhou, Shuangxi; Deng, Fangming; Yu, Lehua; Li, Bing; Wu, Xiang; Yin, Baiqiang

    2016-01-01

    This paper presents a passive wireless humidity sensor for concrete monitoring. After discussing the transmission of electromagnetic wave in concrete, a novel architecture of wireless humidity sensor, based on Ultra-High Frequency (UHF) Radio Frequency Identification (RFID) technology, is proposed for low-power application. The humidity sensor utilizes the top metal layer to form the interdigitated electrodes, which were then filled with polyimide as the humidity sensing layer. The sensor interface converts the humidity capacitance into a digital signal in the frequency domain. A two-stage rectifier adopts a dynamic bias-voltage generator to boost the effective gate-source voltage of the switches in differential-drive architecture. The clock generator employs a novel structure to reduce the internal voltage swing. The measurement results show that our proposed wireless humidity can achieve a high linearity with a normalized sensitivity of 0.55% %RH at 20 °C. Despite the high losses of concrete, the proposed wireless humidity sensor achieves reliable communication performances in passive mode. The maximum operating distance is 0.52 m when the proposed wireless sensor is embedded into the concrete at the depth of 8 cm. The measured results are highly consistent with the results measured by traditional methods. PMID:27657070

  7. New model of universal gas-filled neutron tube

    International Nuclear Information System (INIS)

    Bespalov, D.F.; Bessarabskii, I.G.; Voitsik, L.R.; Mints, A.Z.

    1985-01-01

    The UNG-1 gas-filled neutron tube is serially produced. In type UNG neutron generators, the tube operates in the pulsed mode in the high voltage doubling circuit arrangement. During extended operation, its advantages were discovered: long operating time, fairly stable neutron yield, and simplicity of use and operation. However, the mean neutron yield (approx.10 7 s -1 ) generated by the tube in the optimal mode at the present time proved to be inadequate in solving numerous geophysical problems. So a model of a neutron tube, model UNG-2, was designed, ensuring an enhanced neutron yield of 10 8 s -1 in the continuous-operating mode. When the tube is connected to the high voltage doubling circuit, the mean neutron yield is only somewhat in excess of the neutron yield from the UNG-1 tube

  8. Application of super workable concrete to main tower of cable-stayed prestressed concrete bridge. ; Kiba park grand bridge. PC shachokyo no shuto eno tekiyo. ; Kiba koen ohashi

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Y.; Shindo, T.; Sakamoto, A. (Taisei Corp., Tokyo (Japan))

    1993-08-01

    The Kiba Park Grand Bridge is a cable-stayed prestressed concrete (PC) bridge with a length of 186m. The main tower of this PC cable-stayed bridge consists of a pair of vertical columns with height of 60m and a beam connecting the columns. For the purpose of the advanced efficiency of construction without formwork and removal work and the improvement of durability, the precast buried formwork made of polymer impregnated concrete formwork was adopted. Approximate 650 cubic meter of super workable concrete was placed for the upper part ranging from 7th to 17th blocks of vertical columns and the beam. Blast furnace cement B and fly ash were used as binder. Naphthalenesulfonic acid type high performance water reducing agent and lignosulfonic acid type AE (air-entraining) water reducing agent were used as admixtures. Super workable concrete was mixed using forced double-axle mixers in the ready-mixed concrete plant. Satisfactory quality of the fresh concrete and strength of the hardened concrete were obtained. 2 refs., 11 figs., 3 tabs.

  9. Microhardness of bulk-fill composite materials

    OpenAIRE

    Kelić, Katarina; Matić, Sanja; Marović, Danijela; Klarić, Eva; Tarle, Zrinka

    2016-01-01

    The aim of the study was to determine microhardness of high- and low-viscosity bulk-fill composite resins and compare it with conventional composite materials. Four materials of high-viscosity were tested, including three bulk-fills: QuiXfi l (QF), x-tra fil (XTF) and Tetric EvoCeram Bulk Fill (TEBCF), while nanohybrid composite GrandioSO (GSO) served as control. The other four were low-viscosity composites, three bulk-fill materials: Smart Dentin Replacement (SDR), Venus Bulk Fill (VBF) and ...

  10. Locomotion and claw disorders in Norwegian dairy cows housed in freestalls with slatted concrete, solid concrete, or solid rubber flooring in the alleys.

    Science.gov (United States)

    Fjeldaas, T; Sogstad, A M; Osterås, O

    2011-03-01

    This study was part of a cross-sectional project on freestall housing, and the aim was to compare locomotion and claw disorders in freestall dairy cattle herds with slatted concrete, solid concrete, or solid rubber flooring in the alleys. The final population for studying claw disorders consisted of 66 dairy herds with 2,709 dry or lactating cows, whereas the population for studying locomotion consisted of 54 herds with 2,216 cows. All herds used Norwegian Red as the main breed. The herds were visited by 15 trained claw trimmers one time during the period from the beginning of February to summer let-out onto pasture in 2008. The trimmers assessed locomotion scores (LocS) of all cows before trimming. At trimming, claw disorders were diagnosed and recorded in the Norwegian Claw Health Card. Estimates describing locomotion and claw disorders in the hind feet were identified by use of multivariable models fit with LocS and each claw disorder as dependent variables, respectively. Herd nested within claw trimmer was included in the model as random effects. The odds ratio (OR) of having LocS >2 and LocS >3 was 1.9 and 2.1, respectively, on slatted concrete compared with solid concrete. Fewer cases of dermatitis were found on slatted than solid concrete (OR=0.70) and a tendency was observed for fewer heel horn erosions on slatted concrete than solid rubber (OR=0.47). Hemorrhages of the white line and sole were more prevalent in herds housed on slatted and solid concrete than in those housed on solid rubber (OR=2.6 and OR=2.1, respectively). White line fissures were also more prevalent in herds housed on slatted and solid concrete than in those housed on solid rubber (OR=2.1 and OR=2.0, respectively). Double soles were more prevalent on solid concrete than solid rubber (OR=4.4). However, sole ulcers were less prevalent in herds with slatted and solid concrete than solid rubber (OR=0.39 and OR=0.53, respectively). Fewer corkscrewed claws were found on slatted concrete than

  11. Review of fill mining technology in Canada

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K. H.; Hedley, D. G.F.

    1980-05-15

    The Canadian mining industry has a long history of being in the fore-front in developing new technology in underground hardrock mines. Examples include the development of hydraulic and cemented fills, undercut-and-fill, mechanized cut-and-fill, post pillar, vertical retreat and blasthole mining methods. The evolution of this technology is briefly described in an historical review. Backfill serves many functions, although it is generally considered in terms of its support capabilities. These functions, mainly related to the mining method used, are evaluated in regard to regional support, pillar support, fill roof, working floor, dilution control and waste disposal. With the advent of blasthole and vertical retreat methods for pillar recovery operations, the freestanding height of backfill walls has assumed greater importance. Consequently, more attention is being given to what fill properties are required to achieve fill wall exposures up to 25 m wide by 90 m high. With the large increases in energy costs, alternatives to partially replace Portland cement in fill are being examined. The validation of mining concepts and the interaction of backfill is perhaps best evaluated by in-situ measurements. Examples are given of stress, deformation and fill pressure measurements in longitudinal cut-and-fill, post pillar mining and blasthole stoping with delayed fill which were taken in several mines in Canada. Finally, the overall design procedure used in deciding mining method, stope and pillar dimensions, sequence of extraction, fill properties and support systems at a new mine is described.

  12. Durability of Self Compacting Concrete

    International Nuclear Information System (INIS)

    Benmarce, A.; Boudjehem, H.; Bendjhaiche, R.

    2011-01-01

    Self compacting concrete (SCC) seem to be a very promising materials for construction thanks to their properties in a fresh state. Studying of the influence of the parameters of specific designed mixes to their mechanical, physical and chemical characteristics in a state hardened is an important stage so that it can be useful for new-to-the-field researchers and designers (worldwide) beginning studies and work involving self compacting concrete. The objective of this research is to study the durability of self compacting concrete. The durability of concrete depends very much on the porosity; the latter determines the intensity of interactions with aggressive agents. The pores inside of concrete facilitate the process of damage, which began generally on the surface. We are interested to measure the porosity of concrete on five SCC with different compositions (w/c, additives) and vibrated concrete to highlight the influence of the latter on the porosity, thereafter on the compressive strength and the transfer properties (oxygen permeability, chloride ion diffusion, capillary absorption). (author)

  13. Monitoring device for reinforced concrete

    International Nuclear Information System (INIS)

    Matsuzaki, Tetsuo; Saito, Koichi; Furukawa, Hideyasu.

    1994-01-01

    A reactor container made of reinforced concretes is monitored for the temperature at each of portions upon placing concretes under construction of a plant, upon pressure-proof test and during plant operation. That is, optical fibers are uniformly laid spirally throughout the inside of the concretes. Pulses are injected from one end of the optical fibers, and the temperature at a reflection point can be measured by measuring specific rays (Raman scattering rays) among lights reflected after a predetermined period of time. According to the present invention, measurement for an optional position within a range where one fiber cable is laid can be conducted. Accordingly, it is possible to conduct temperature control upon concrete placing and apply temperature compensation for the measurement for stresses of the concretes and the reinforcing steels upon container pressure-proof. Further, during plant operation, if the temperature of the concretes rises due to thermal conduction of the temperature in the container, integrity of the concretes can be ensured by a countermeasures such as air conditioning. (I.S.)

  14. The characterization of cement waste form for final disposal of decommissioning concrete wastes

    International Nuclear Information System (INIS)

    Lee, Yoon-ji; Lee, Ki-Won; Min, Byung-Youn; Hwang, Doo-Seong; Moon, Jei-Kwon

    2015-01-01

    Highlights: • Decommissioning concrete waste recycling and disposal. • Compressive strength of cement waste form. • Characteristic of thermal resistance and leaching of cement waste form. - Abstract: In Korea, the decontamination and decommissioning of KRR-1, 2 at KAERI have been under way. The decommissioning of the KRR-2 was finished completely by 2011, whereas the decommissioning of KRR-1 is currently underway. A large quantity of slightly contaminated concrete waste has been generated from the decommissioning projects. The concrete wastes, 83ea of 200 L drums, and 41ea of 4 m 3 containers, were generated in the decommissioning projects. The conditioning of concrete waste is needed for final disposal. Concrete waste is conditioned as follows: mortar using coarse and fine aggregates is filled with a void space after concrete rubble pre-placement into 200 L drums. Thus, this research developed an optimizing mixing ratio of concrete waste, water, and cement, and evaluated the characteristics of a cement waste form to meet the requirements specified in the disposal site specific waste acceptance criteria. The results obtained from a compressive strength test, leaching test, and thermal cycling test of cement waste forms conclude that the concrete waste, water, and cement have been suggested as an optimized mixing ratio of 75:15:10. In addition, the compressive strength of the cement waste form was satisfied, including a fine powder up to a maximum of 40 wt% in concrete debris waste of about 75%. According to the scale-up test, the mixing ratio of concrete waste, water, and cement is 75:10:15, which meets the satisfied compressive strength because of an increase in the particle size in the waste

  15. Feasibility of atomic and molecular laser induced breakdown spectroscopy (LIBS) to in-situ determination of chlorine in concrete : final report.

    Science.gov (United States)

    2016-10-01

    Laser-induced breakdown spectroscopy (LIBS) has been studied as a fast method of detecting chlorine in concrete samples. Both single pulse (SP) and double pulse (DP) experiments have been tested. Several combinations of lasers (Neodymium-Yttrium Alum...

  16. Long-life concrete : how long will my concrete last?

    Science.gov (United States)

    2013-10-01

    There is an ongoing discussion about moving toward performance-based specifications for concrete pavements. This document seeks to : move the discussion forward by outlining the needs and the challenges, and proposing some immediate actions. However,...

  17. Urban Experiments and Concrete Utopias

    DEFF Research Database (Denmark)

    Andersson, Lasse

    2009-01-01

    The paper explores how concrete urban experiments can challenge the pecuniary version of the experience city and stimulate a locally rooted and democratic version of an experience based city using heterotopias and concrete utopias as the link between top down planning and bottom up experiments...... administrations with public participation in order to shape a cultural agenda. The second part of the paper looks at two cases: NDSM in Amsterdam and Platform4 in Aalborg suggesting that it is concrete urban experiments like these that can create a link between visions and local reality in the Experience city...

  18. PCM Concrete. [Phase Change Materials

    Energy Technology Data Exchange (ETDEWEB)

    Juul Andersen, T. [Danish Technological Institute, Taastrup (Denmark); Poulsen, H.-H. [BASF A/S, Roedekro (Denmark); Passov, F. [Spaencom A/S, Hedehusene (Denmark); Heiselberg, P. [Aalborg Univ..Aalborg (Denmark)

    2013-04-01

    PCM-Concrete was a research and development project launched in 2009 and finished in 2012. The project, which was funded by The Danish National Advanced Technology Foundation, had a total budget of 1.7 million Euros and included 4 partners: Danish Technological Institute (project manager), Aalborg University, BASF A/S and Spaencom A/S. The overall vision of the project was to reduce energy consumption for heating and cooling in buildings by developing high-performance concrete structures microencapsulated Phase Change Materials (PCM). The PCM used in the project was Micronal produced by BASF A/S. Micronal is small capsules with an acrylic shell and inside a wax with a melting point at approx. 23 deg. C equal to a comfortable indoor temperature. During the melting process thermal energy is transferred to chemical reaction (melting/solidification) depending on PCM being heated up or cooled down. Adding Micronal to concrete would theoretically increase the thermal mass of the concrete and improve the diurnal heat capacity which is the amount of energy that can be stored and released during 24 hours. Nevertheless, it is a relatively new technology that has not received much attention, yet. In the PCM-Concrete project 5 main investigations were carried out: 1) Development of concrete mix design with PCM. 2) Investigation of thermal properties of the PCM concrete: thermal conductivity, specific heat capacity, density. 3) Up-scaling the research to industrial production of PCM-concrete structures. 4) Testing energy efficiency in full scale. 5) Confronting aesthetic and acoustic barriers to full exploitation of the potential of PCM-concrete structures. The results from the test program showed: 1) That the diurnal heat storage capacity is higher for all 4 hollow core decks with tiles attached compared to the reference hollow core deck. 2) The hollow core decks with concrete tiles without PCM performs slightly better than the tiles with PCM. 3) That is was impossible to

  19. Review of concrete properties for prestressed concrete pressure vesssels

    International Nuclear Information System (INIS)

    Nanstad, R.K.

    1976-10-01

    The desire for increasing power output along with safety requirements has resulted in consideration of the prestressed concrete pressure vessel (PCPV) for most current nuclear reactor systems, as well as for the very-high-temperature reactor for process heat and as primary pressure vessels for coal conversion systems. Results are presented of a literature review to ascertain current knowledge regarding plain concrete properties under conditions imposed by a mass concrete structure such as PCRV. The effects of high temperature on such properties as strength, elasticity, and creep are discussed, as well as changes in thermal properties, multiaxial behavior, and the mechanisms thought to be responsible for the observed behavior. In addition, the effects of radiation and moisture migration are discussed. It is concluded that testing results found in the technical literature show much disagreement as to the effects of temperature on concrete properties. The variations in concrete mixtures, curing and testing procedures, age at loading, and moisture conditions during exposure and testing are some of the reasons for such disagreement. Test results must be limited, in most cases, to the materials and conditions of a given test rather than applied to such a general class of materials such as concrete. It is also concluded that sustained exposure of normal concretes to current PCRV operating conditions will not result in any significant loss of properties. However, lack of knowledge regarding effects of temperatures exceeding 100 0 C (212 0 F), moisture migration, and multiaxial behavior precludes a statement advocating operation beyond current design limits. The report includes recommendations for future research on concrete for PCPVs

  20. Betonreparationers holdbarhed (Durability of Concrete Repairs)

    DEFF Research Database (Denmark)

    Brimnes, Eydbjørn; Dali, Bogi í; Larsen, Erik Stoklund

    1999-01-01

    Concrete repairs on 11 pillars on bridges built in the sixties and repaired 8 to 9 years ago have been examined. Especially the chloride penetration in the repair concrete have been measured. Chloride penetration in the repair concrete is much lower than in the original concrete....

  1. Biaxial Stress Tests of Plain Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.K.; Cho, M.S.; Song, Y.C. [Korea Electric Power Research Institute, Taejon (Korea)

    2001-07-01

    Containment concrete specimens(4000, 5000psi) were tested under biaxial stress and presented basic physical properties and biaxial failure envelops for the concrete specimens. Failure behaviors of concrete under biaxial stress were assessed with stress-strain responses and failure modes. Here provided real test data to develop nonlinear finite element concrete models. (author). 15 refs., 46 figs., 4 tabs.

  2. Durability of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

    1996-01-01

    The planned research will indicate, whether fibre reinforced concrete has better or worse durability than normal concrete. Durability specimens will be measured on cracked as well as uncracked specimens. Also the pore structure in the concrete will be characterized.Keywords: Fibre reinforced...... concrete, durability, pore structure, mechanical load...

  3. Rotational Capacity of Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Ulfkjær, J. P.; Henriksen, M. S.; Brincker, Rune

    1995-01-01

    programme where 120 reinforced concrete beams, 54 plain concrete beams and 324 concrete cylinders are tested. For the reinforced concrete beams four different parar meters are varied. The slenderness is 6, 12 and 18, the beam depth is 100 mm, 200 mm and 400 mm giving nine different geometries, five...

  4. Effect of Coating Palm Oil Clinker Aggregate on the Engineering Properties of Normal Grade Concrete

    Directory of Open Access Journals (Sweden)

    Fuad Abutaha

    2017-10-01

    Full Text Available Palm oil clinker (POC is a waste material generated in large quantities from the palm oil industry. POC, when crushed, possesses the potential to serve as an aggregate for concrete production. Experimental investigation on the engineering properties of concrete incorporating POC as aggregate and filler material was carried out in this study. POC was partially and fully used to replace natural coarse aggregate. The volumetric replacements used were 0%, 20%, 40%, 60%, 80%, and 100%. POC, being highly porous, negatively affected the fresh and hardened concrete properties. Therefore, the particle-packing (PP method was adopted to measure the surface and inner voids of POC coarse aggregate in the mixtures at different substitution levels. In order to enhance the engineering properties of the POC concrete, palm oil clinker powder (POCP was used as a filler material to fill up and coat the surface voids of POC coarse, while the rest of the mix constituents were left as the same. Fresh and hardened properties of the POC concrete with and without coating were determined, and the results were compared with the control concrete. The results revealed that coating the surface voids of POC coarse with POCP significantly improved the engineering properties as well as the durability performance of the POC concrete. Furthermore, using POC as an aggregate and filler material may reduce the continuous exploitation of aggregates from primary sources. Also, this approach offers an environmental friendly solution to the ongoing waste problems associated with palm oil waste material.

  5. Preliminary investigation on the suitablity of using fiber reinforced concrete in the construction of a hazardous waste disposal vessel

    International Nuclear Information System (INIS)

    Ramey, M.R.; Daie-e, G.

    1988-07-01

    There are certain hazardous wastes that must be contained in an extremely secure vessel for transportation and disposal. The vessel, among other things, must be able to withstand relatively large impacts without rupturing. Such containment vessels therefore must be able to absorb substantial amounts of energy during an impact and still perform their function. One of the impacts that the vessel must withstand is a 30-foot fall onto an unyielding surface. For some disposal scenarios it is proposed to encase the waste in a steel enclosure which is to be surrounded by a thick layer of concrete which, in turn, is encased by a relatively thin steel shell. Tests on concrete in compression and flexure, including static, dynamic and impact tests, have shown that low modulus concretes tend to behave in a less brittle manner than higher modulus concretes. Tests also show that fiber reinforced concretes have significantly greater ductility, crack propagation resistance and toughness than conventional concretes. Since it is known that concrete is a reasonably brittle material, it is necessary to do impact tests on sample containment structures consisting of thin-walled metal containers having closed ends which are filled with concrete, grout, or fiber reinforced concrete. This report presents the results of simple tests aimed at observing the behavior of sample containment structures subjected to impacts due to a fall from 30 feet. 8 figs., 4 tabs

  6. A multifunctional design approach for sustainable concrete : with application to concrete mass products

    NARCIS (Netherlands)

    Hüsken, G.

    2010-01-01

    This thesis provides a multifunctional design approach for sustainable concrete, particularly earth-moist concrete (EMC), with application to concrete mass products. EMC is a concrete with low water content and stiff consistency that is used for the production of concrete mass products, such as

  7. 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.

  8. Temperature Measurement and Damage Detection in Concrete Beams Exposed to Fire Using PPP-BOTDA Based Fiber Optic Sensors.

    Science.gov (United States)

    Bao, Yi; Hoehler, Matthew S; Smith, Christopher M; Bundy, Matthew; Chen, Genda

    2017-10-01

    In this study, distributed fiber optic sensors based on pulse pre-pump Brillouin optical time domain analysis (PPP-BODTA) are characterized and deployed to measure spatially-distributed temperatures in reinforced concrete specimens exposed to fire. Four beams were tested to failure in a natural gas fueled compartment fire, each instrumented with one fused silica, single-mode optical fiber as a distributed sensor and four thermocouples. Prior to concrete cracking, the distributed temperature was validated at locations of the thermocouples by a relative difference of less than 9 %. The cracks in concrete can be identified as sharp peaks in the temperature distribution since the cracks are locally filled with hot air. Concrete cracking did not affect the sensitivity of the distributed sensor but concrete spalling broke the optical fiber loop required for PPP-BOTDA measurements.

  9. Concrete density estimation by rebound hammer method

    International Nuclear Information System (INIS)

    Ismail, Mohamad Pauzi bin; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri; Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin; Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin

    2016-01-01

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite

  10. Operation feedback of hydrogen filling station

    International Nuclear Information System (INIS)

    Pregassame, S.; Barral, K.; Allidieres, L.; Charbonneau, T.; Lacombe, Y.

    2004-01-01

    One of the technical challenges of hydrogen technology is the development of hydrogen infrastructures which satisfy either safety requirements and reliability of filling processes. AIR LIQUIDE realized an hydrogen filling station in Sassenage (France) operational since September 2003. This station is able to fill 3 buses a day up to 350bar by equilibrium with high pressure buffers. In parallel with commercial stations, the group wanted to create a testing ground in real conditions running with several objectives: validate on a full scale bench a simulation tool able to predict the temperature of both gas and cylinder's materials during filling processes; define the best filling procedures in order to reach mass, temperature and filling time targets; analyse the temperature distribution and evolution inside the cylinder; get a general knowledge about hydrogen stations from safety and reliability point of view; operate the first full scale refuelling station in France. The station is also up-graded for 700bar filling from either a liquid hydrogen source or a gas booster, with cold filling possibility. This paper presents the results concerning 350bar filling : thermal effects, optimal filling procedures and influence of parameters such as climatic conditions are discussed. (author)

  11. Dielectric-filled radiofrequency linacs

    Energy Technology Data Exchange (ETDEWEB)

    Faehl, R J; Keinigs, R K; Pogue, E W [Los Alamos National Lab., NM (United States)

    1997-12-31

    High current, high brightness electron beam accelerators promise to open up dramatic new applications. Linear induction accelerators are currently viewed as the appropriate technology for these applications. A concept by Humphries and Hwang may permit radiofrequency accelerators to fulfill the same functions with greater simplicity and enhanced flexibility. This concept involves the replacement of vacuum rf cavities with dielectric filled ones. Simple analysis indicates that the resonant frequencies are reduced by a factor of ({epsilon}{sub 0}/{epsilon}){sup 1/2} while the stored energy is increased by {epsilon}/{epsilon}{sub 0}. For a high dielectric constant like water, this factor can approach 80. A series of numerical calculations of simple pill-box cavities was performed. Eigenfunctions and resonant frequencies for a full system configuration, including dielectric material, vacuum beamline, and a ceramic window separating the two have been computed. These calculations are compared with the results of a small experimental cavity which have been constructed and operated. Low power tests show excellent agreement. (author). 4 figs., 8 refs.

  12. Nondestructive testing of concrete structures

    International Nuclear Information System (INIS)

    Rufino, Randy R.; Relunia, Estrella

    1999-01-01

    Nondestructive testing of concrete is highly inhomogeneous which makes it cumbersome to setup experimental procedures and analyze experimental data. However, recent research and development activities have discovered the different methods of NDT, like the electromagnetic method, ultrasonic pulse velocity test, pulse echo/impact echo test, infrared thermography, radar or short pulse radar techniques, neutron and gamma radiometry, radiography, carbonation test and half-cell potential method available for NDT of concrete structures. NDT of concrete is emerging as a useful tool for quality control and assurance. This papers also describes the more common NDT methods discussed during the two-week course on 'Nondestructive Testing of Concrete Structures', held at the Malaysian Institute for Nuclear Technology Research (MINT) in Malaysia, which was jointly organized by MINT and the International Atomic Energy Agency (IAEA)

  13. Tests on standard concrete samples

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Compression and tensile tests on standard concrete samples. The use of centrifugal force in tensile testing has been developed by the SB Division and the instruments were built in the Central workshops.

  14. Sustainable concretes for transportation infrastructure.

    Science.gov (United States)

    2010-07-01

    performance in concrete for structural and transportation applications. Based on the challenges associated with coal ash (including SDA) and the economic costs linked to cement production, this research seeks to develop an environmentally friendly an...

  15. Monitoring water loss form fresh concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2006-01-01

    Desiccation of concrete before or during setting may lead to detrimental plastic shrinkage cracking in the concrete surface zone. Cracking due to plastic shrinkage is a major technological problem for any concrete, however, modern high-performance concretes are especially susceptible to this...... determination of the evaporation loss from hardening concrete and thus better possibility for preventing curing problems, including detrimental crack damage due to plastic shrinkage....

  16. An international data base of nuclear concrete containment ageing

    International Nuclear Information System (INIS)

    Seni, C.; Ianko, L.

    1994-01-01

    The ageing of nuclear structures is of special interest because of the extended service life expected of these structures, and the potential impact of their deterioration on safety and reliability. Although there are databases about concrete, they address properties in general, not performance. In 1992, the IAEA, in collaboration with AECL, set out to create a new database that would fill the gap. Functional ageing, i.e. deterioration of leak-tightness, was to be included, not just structural ageing, i.e. deterioration of load-bearing capacity. This paper outlines the project of creating the database

  17. A Study on the Properties and Chloride Resistance of Modified Sulfur Concrete for Nuclear Power Plant and Marine Structures

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Soon Myun; Chang, Hyun Young; Park, Heung Bae [KEPCO EnC, Seongnam (Korea, Republic of)

    2015-05-15

    The mechanical, physical and chemical properties of concrete with modified sulfur have been compared and assessed against ordinary concrete. As its excellent chloride resistance and extended service life have been verified, the technology to apply modified sulfur to the construction of nuclear power plant and marine structures has been developed and secured. Recently, modified sulfur concrete has been applied for road pavement and repair works in more than 20 sites including highway and airport in Korea. Also, in the U.S., Federal Highway Administration and Virginia Department of Transportation are implementing tests to apply modified sulfur to bridge road pavement, and the modified sulfur concrete has been recognized for its good performance. Based on these cases, this study carried out tests on physical, mechanical and chemical properties of concrete after adding modified sulfur by building concrete specimens based on the concrete mix design employed to construct the Shin-Kori Units 3 and 4 containment building. Multiple tests were performed particularly for chemical resistance, a factor directly related to concrete service life. As a result, it has been verified that concrete with 5% modified sulfur content relative to cement weight has equal mechanical properties (compressive strength, tensile strength, etc.) and much better workability (slump change) and chemical resistance (resistance to chloride ion penetration, concrete carbonation) compared with ordinary concrete. Based on this, it has been concluded that an addition of modified sulfur can double the service life of concrete. In general, studies demonstrate that a significant amount of slag should be mixed into concrete to raise chemical resistance (but with decreasing mechanical properties). Considering this, this study is unparalleled.

  18. A Study on the Properties and Chloride Resistance of Modified Sulfur Concrete for Nuclear Power Plant and Marine Structures

    International Nuclear Information System (INIS)

    Wang, Soon Myun; Chang, Hyun Young; Park, Heung Bae

    2015-01-01

    The mechanical, physical and chemical properties of concrete with modified sulfur have been compared and assessed against ordinary concrete. As its excellent chloride resistance and extended service life have been verified, the technology to apply modified sulfur to the construction of nuclear power plant and marine structures has been developed and secured. Recently, modified sulfur concrete has been applied for road pavement and repair works in more than 20 sites including highway and airport in Korea. Also, in the U.S., Federal Highway Administration and Virginia Department of Transportation are implementing tests to apply modified sulfur to bridge road pavement, and the modified sulfur concrete has been recognized for its good performance. Based on these cases, this study carried out tests on physical, mechanical and chemical properties of concrete after adding modified sulfur by building concrete specimens based on the concrete mix design employed to construct the Shin-Kori Units 3 and 4 containment building. Multiple tests were performed particularly for chemical resistance, a factor directly related to concrete service life. As a result, it has been verified that concrete with 5% modified sulfur content relative to cement weight has equal mechanical properties (compressive strength, tensile strength, etc.) and much better workability (slump change) and chemical resistance (resistance to chloride ion penetration, concrete carbonation) compared with ordinary concrete. Based on this, it has been concluded that an addition of modified sulfur can double the service life of concrete. In general, studies demonstrate that a significant amount of slag should be mixed into concrete to raise chemical resistance (but with decreasing mechanical properties). Considering this, this study is unparalleled

  19. Modelling reinforcement corrosion in concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, Mette Rica; Stang, Henrik

    2012-01-01

    A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

  20. Electrically conductive polymer concrete coatings

    Science.gov (United States)

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  1. Annotated Bibliography: Polymers in Concrete.

    Science.gov (United States)

    1982-10-01

    Berka , L., "Determination of the Creeping and Relaxation Functions . from the Results of the Creeping and Relaxation Tests," RILE. Symposium on Synthetic...However, for both foamed glass and . Mearlcrete concretes the agreement between prediction and experiment is not too bad . The reason for the serious...chemical resistance of various concretes is in the following order: (good) PIAC > AC > WCC ( bad ). The aggressive chemical agents that attack markedly

  2. Concrete with supplementary cementitious materials

    OpenAIRE

    Jensen, Ole M; Kovler, Konstantin; De Belie, Nele

    2016-01-01

    This volume contains the proceedings of the MSSCE 2016 conference segment on “Concrete with Supplementary Cementitious Materials” (SCM). The conference segment is organized by the RILEM technical committee TC 238-SCM: Hydration and microstructure of concrete with supplementary cementitious materials. TC 238-SCM started activities in 2011 and has about 50 members from all over the world. The main objective of the committee is to support the increasing utilisation of hydraulic...

  3. Porous Structure of Road Concrete

    OpenAIRE

    Пшембаев, М. К.; Гиринский, В. В.; Ковалев, Я. Н.; Яглов, В. Н.; Будниченко, С. С.

    2016-01-01

    Having a great number of concrete structure classifications it is recommended to specify the following three principal types: microstructure – cement stone structure; mesostructure – structure of cement-sand mortar in concrete; macrostucture – two-component system that consists of mortar and coarse aggregate. Every mentioned-above structure has its own specific features which are related to the conditions of their formation. Thus, microstructure of cement stone can be characterized by such st...

  4. Chlorine signal attenuation in concrete.

    Science.gov (United States)

    Naqvi, A A; Maslehuddin, M; Ur-Rehman, Khateeb; Al-Amoudi, O S B

    2015-11-01

    The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Concrete waste reduction of 50%

    International Nuclear Information System (INIS)

    Vos, R.M. de; Van der Wagt, K.M.; Van der Kruk, E.; Meeussen, H.W.

    2016-01-01

    During decommissioning quite a volume of concrete waste is produced. The degree of activation of the waste can range from clearly activated material to slightly activated or contaminated concrete. The degree of activation influences the applicable waste management processes that can be applied. The subsequent waste management processes can be identified for concrete waste are; disposal, segregation, re-use, conditional release and release. With each of these steps, the footprint of radioactive decommissioning waste is reduced. Future developments for concrete waste reduction can be achieved by applying smart materials in new build facilities (i.e. fast decaying materials). NRG (Nuclear Research and consultancy Group) has investigated distinctive waste management processes to reduce the foot-print of concrete waste streams resulting from decommissioning. We have investigated which processes can be applied in the Netherlands, both under current legislation and with small changes in legislation. We have also investigated the separation process in more detail. Pilot tests with a newly patented process have been started in 2015. We expect that our separation methods will reduce the footprint reduction of concrete waste by approximately 50% due to release or re-use in the nuclear sector or in the conventional industry. (authors)

  6. Numerical Study on the Behaviour of Reduced Beam Section Presence in Rectangular Concrete Filled Tubes Connection

    Science.gov (United States)

    Amalia, A. R.; Suswanto, B.; Kristijanto, H.; Irawan, D.

    2018-01-01

    This paper discusses about the behaviour of two types of RCFT column connections with steel beams due to cyclic loads using software based on finite element method ABAQUS 6.14. This comparison involves modelling RCFT connections with rigid connection that do not allow any deformation and rotation in the joint. There are two types of model to be compared: BB and BRBS which include RCFT connections to ordinary beam without RBS (BB) and to Reduce Beam Section Beam (BRBS). The models behaviour can be discussed in this study are stress value, von misses stress pattern and rotational degree of each model. From the von misses stress pattern value, it found that the highest regions of stress occurs in vicinity of beam flange near column face for connection without RBS (BB). For earthquake resistant building, that behaviour needs to be avoided because sudden collapse often happen in that joint connection. Moreover, the connection with the presence of RBS (BRBS), the highest regions of stress occurs in reduced beam section of the beam, it means that the failure might be happen as proposed plan. The ultimate force that can be restrained by BB model (402 kN) is higher than BRBS model (257,18 kN) because of reducing of flange area. BRBS model has higher rotation angle (0,057 rad) than BB model (0,045 rad). The analysis results also observed that cyclic performances of the moment connection with RBS (BRBS) were more ductile than the connection with ordinary beam (BB).

  7. Iron filled carbon nanostructures from different precursors

    International Nuclear Information System (INIS)

    Costa, S.; Borowiak-Palen, E.; Bachmatiuk, A.; Ruemmeli, M.H.; Gemming, T.; Kalenczuk, R.J.

    2008-01-01

    Here, we present a study on the synthesis of different nanostructures with one single-step in situ filling (encapsulation) via carbon vapor deposition (CVD). Ferrocene, acetylferrocene and iron (II) nitrate as iron precursors were explored. The application of each of these compounds resulted in different carbon nanomaterials such as: iron filled multiwalled carbon nanotubes with a low filling ratio (Fe-MWCNT), iron filled nanocapsules and unfilled MWCNT. The as-produced samples were purified by high temperature annealing and acid treatment. The purified materials were characterised using transmission electron microscopy (TEM) and Raman spectroscopy

  8. Characterization of Low Density Glass Filled Epoxies

    National Research Council Canada - National Science Library

    Quesenberry, Matthew

    2003-01-01

    This report discusses the experimental determination and modeling of several thermophysical and mechanical properties of glass filled epoxy composite systems for potential use as electronic potting compounds...

  9. Optimum concrete compression strength using bio-enzyme

    OpenAIRE

    Bagio Tony Hartono; Basoeki Makno; Tistogondo Julistyana; Pradana Sofyan Ali

    2017-01-01

    To make concrete with high compressive strength and has a certain concrete specifications other than the main concrete materials are also needed concrete mix quality control and other added material is also in line with the current technology of concrete mix that produces concrete with specific characteristics. Addition of bio enzyme on five concrete mixture that will be compared with normal concrete in order to know the optimum level bio-enzyme in concrete to increase the strength of the con...

  10. Corrosion of the reinforcing steel in the inhibited sawdust concrete construction

    International Nuclear Information System (INIS)

    Kobuliev, Z.V.

    2005-01-01

    In the article described the way of protection of the reinforcing steel in sawdust concrete construction by adding to inhibited sawdust concrete mixture containing nitrate-nitride calcium chloride (NNCC) and (NH 4 ) 2 Cr 2 O 7 , also NaNO 2 + NaNO 3 +NH 4 Cl and CaCl 2 +(NH 4 ) 2 +Cr 2 . There is determined, that the use of these additives increase strength properties of sawdust concrete at 28 day to 40-55% in comparison with sawdust concrete containing CaCl 2 , and decrease its corrosion-resistance activity, and provided reliability under condition of double excess of inhibitor ions (NO 2- , Cr 2 O 7- ) in comparison with ions (Cl-)

  11. Activated carbon as a pseudo-reference electrode for electrochemical measurement inside concrete

    NARCIS (Netherlands)

    Abbas, Yawar; Olthuis, Wouter; van den Berg, Albert

    2015-01-01

    The application of Kynol based activated carbon (KAC) as a pseudo-reference electrode for potentiometric measurement inside concrete is presented. Due to its high surface area the activated carbons has a large electrical double layer capacitance (EDLC > 50 F g(-1)) and are used as electrode material

  12. Assessment of concrete characteristics during the deliberate deformation of a flexible mould after casting

    NARCIS (Netherlands)

    Schipper, H.R.; Grunewald, S.; Troian, S.; Raghunath, P.; Schlangen, H.E.J.G.; Copuroglu, O.; Pecur, I.B.; Baricevic, A.; Stirmer, N; Bjegovic, D.

    2017-01-01

    Expensive CNC (computer numerical controlled)-milled formwork is required for the production of double-curved precast concrete elements for cladding or shell structures. The innovative flexible mould method for economically efficient and sustainable production of such elements, developed at Delft

  13. Evaluating a Prefabricated Submerged Breakwater and Double-T Sill for Beach Erosion Prevention, Cape May Point, NJ

    National Research Council Canada - National Science Library

    Stauble, Donald K; Giovannozzi, Michael A

    2003-01-01

    ...) and a linear prefabricated concrete sill called the Double-T across the seaward end of two adjacent groin compartments, in order to assess the effectiveness of these structures in retaining sand...

  14. Characterization of mixed mode crack opening in concrete

    DEFF Research Database (Denmark)

    Jacobsen, Jonas Sejersbøl; Poulsen, Peter Noe; Olesen, John Forbes

    2012-01-01

    components of the mixed mode displacement are measured using a custom made orthogonal gauge, and the measurements are used directly as the closed loop control signals. A double notch, concrete specimen is used for the crack investigation. The tests are divided into two steps, a pure Mode I opening step......In real concrete structures cracks often open in mixed mode after their initiation. To capture the direct material behavior of a mixed mode crack opening a stiff biaxial testing machine, capable of imposing both normal and shear loads on a given crack area, has been applied. The opening and sliding......, where a macro crack is initiated in the specimen followed by the mixed mode opening step. The high stiffness of the set-up together with the closed control loop ensures a stable crack initiation followed by a controllable mixed mode opening. The deep notches result in a plane crack, only influenced...

  15. Retrofitting of Reinforced Concrete Beams using Reactive Powder Concrete (RPC)

    Science.gov (United States)

    Karthik, S.; Sundaravadivelu, Karthik

    2017-07-01

    Strengthening of existing damaged structures is one of the leading studies in civil engineering. The purpose of retrofitting is to structurally treat the member with an aim to restore the structure to its original strength. The focus of this project is to study the behaviour of damaged Reinforced Concrete beam retrofitted with Reactive Powder Concrete (RPC) Overlay. Reinforced concrete beams of length 1200 mm, width 100 mm and depth 200 mm were casted with M30 grade of concrete in the laboratory and cured for 28 days. One beam is taken as control and are tested under two point loading to find out ultimate load. Remaining beams are subjected to 90 % ultimate load of control beams. The partially damaged beams are retrofitted with Reactive Powder Concrete Overlay at the full tension face of the beam and side overlay depends upon the respectable retrofitting techniques with 10 mm and 20 mm thick layer to find optimum. Materials like steel fibres are added to enhance the ductility by eliminating coarse particle for homogeneity of the structure. Finally, the modes of failure for retrofitted beams are analysed experimentally under two point loading & compared the results with Control beam.

  16. Development of a concrete placement device for support of abandoned mines

    International Nuclear Information System (INIS)

    Burnett, M.; Burnett, J.M.; El-Korchi, T.

    1994-01-01

    Burnett Associates, Inc. (BAI), under contract to the US Bureau of Mines, has developed a reliable and cost effective method of remote placement of point support columns in abandoned mines through boreholes to provide local support, especially under surface structures in subsidence prone areas. The development of the system to remotely build a concrete support cylinder in an abandoned mine required the coordination of mechanical system and concrete design. The mechanical system was designed to remote place concrete in a cylindrical shape. The concrete was designed to meet the requirements of low slump with high enough strength to resist the forces applied by the ground above mine. The support cylinder is fabricated through an 8-inch borehole by pumping concrete through a second 4-in pipe inside the borehole. The 4-in pipe has a flexible trunk on the lower end that is bent from the surface when it is inside the mine void. When pumping starts, the 4-in pipe is rotated and a spiral of concrete is placed on the mine floor. Operation continues until the concrete seals at the roof. A normal weight concrete as recommended by ACI 211 having a maximum slump of 1--2 in, a maximum coarse aggregate size of 1/2 in, and a minimum compressive strength of 5,000 psi was used. Cylinders have been fabricated to roof heights of 6 ft. There does not appear to be a technical height limitation. The concrete cylinder can support up to 40 x 10 6 lbs when fully cured and filled with gravel, depending on cylinder diameter

  17. Prediction of concrete strength in massive structures

    International Nuclear Information System (INIS)

    Sakamoto, T.; Makino, H.; Nakane, S.; Kawaguchi, T.; Ohike, T.

    1989-01-01

    Reinforced concrete structures of a nuclear power plant are mostly of mass concrete with cross-sectional dimensions larger than 1.0 m. The temperature of concrete inside after placement rises due to heat of hydration of cement. It is well known that concrete strengths of mass concrete structure subjected to such temperature hysteresis are generally not equal to strengths of cylinders subjected to standard curing. In order to construct a mass concrete structure of high reliability in which the specified concrete strength is satisfied by the specified age, it is necessary to have a thorough understanding of the strength gain property of concrete in the structure and its relationships with the water-cement ratio of the mix, strength of standard-cured cylinders and the internal temperature hysteresis. This report describes the result of studies on methods of controlling concrete strength in actual construction projects

  18. ASTM STANDARD GUIDE FOR EVALUATING DISPOSAL OPTIONS FOR REUSE OF CONCRETE FROM NUCLEAR FACILITY DECOMMISSIONING

    International Nuclear Information System (INIS)

    Phillips, Ann Marie; Meservey, Richard H.

    2003-01-01

    Within the nuclear industry, many contaminated facilities that require decommissioning contain huge volumes of concrete. This concrete is generally disposed of as low-level waste at a high cost. Much of the concrete is lightly contaminated and could be reused as roadbed, fill material, or aggregate for new concrete, thus saving millions of dollars. However, because of the possibility of volumetric contamination and the lack of a method to evaluate the risks and costs of reusing concrete, reuse is rarely considered. To address this problem, Argonne National Laboratory-East (ANL-E) and the Idaho National Engineering and Environmental Laboratory teamed to write a ''concrete protocol'' to help evaluate the ramifications of reusing concrete within the U.S. Department of Energy (DOE). This document, titled the Protocol for Development of Authorized Release Limits for Concrete at U.S. Department of Energy Site (1) is based on ANL-E's previously developed scrap metal recycle protocols; on the 10-step method outlined in DOE's draft handbook, Controlling Release for Reuse or Recycle of Property Containing Residual Radioactive Material (2); and on DOE Order 4500.5, Radiation Protection of the Public and the Environment (3). The DOE concrete protocol was the basis for the ASTM Standard Guide for Evaluating Disposal Options for Concrete from Nuclear Facility Decommissioning, which was written to make the information available to a wider audience outside DOE. The resulting ASTM Standard Guide is a more concise version that can be used by the nuclear industry worldwide to evaluate the risks and costs of reusing concrete from nuclear facility decommissioning. The bulk of the ASTM Standard Guide focuses on evaluating the dose and cost for each disposal option. The user calculates these from the detailed formulas and tabulated data provided, then compares the dose and cost for each disposal option to select the best option that meets regulatory requirements. With this information

  19. HYDRAULIC AND PHYSICAL PROPERTIES OF SALTSTONE GROUTS AND VAULT CONCRETES

    International Nuclear Information System (INIS)

    Dixon, K.; Harbour, J.; Phifer, M.

    2008-01-01

    The Saltstone Disposal Facility (SDF), located in the Z-Area of the Savannah River Site (SRS), is used for the disposal of low-level radioactive salt solution. The SDF currently contains two vaults: Vault 1 (6 cells) and Vault 4 (12 cells). Additional disposal cells are currently in the design phase. The individual cells of the saltstone facility are filled with saltstone. Saltstone is produced by mixing the low-level radioactive salt solution, with blast furnace slag, fly ash, and cement (dry premix) to form a dense, micro-porous, monolithic, low-level radioactive waste form. The saltstone is pumped into the disposal cells where it subsequently solidifies. Significant effort has been undertaken to accurately model the movement of water and contaminants through the facility. Key to this effort is an accurate understanding of the hydraulic and physical properties of the solidified saltstone. To date, limited testing has been conducted to characterize the saltstone. The primary focus of this task was to estimate the hydraulic and physical properties of three types of saltstone and two vault concretes. The saltstone formulations included saltstone premix batched with (1) Deliquification, Dissolution, and Adjustment (DDA) salt simulant (w/pm 0.60), (2) Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) salt simulant (w/pm 0.60), and (3) Salt Waste Processing Facility (SWPF) salt simulant (w/pm 0.60). The vault concrete formulations tested included the Vault 1/4 concrete and two variations of the Vault 2 concrete (Mix 1 and Mix 2). Wet properties measured for the saltstone formulations included yield stress, plastic viscosity, wet unit weight, bleed water volume, gel time, set time, and heat of hydration. Hydraulic and physical properties measured on the cured saltstone and concrete samples included saturated hydraulic conductivity, moisture retention, compressive strength, porosity, particle density, and dry bulk density. These properties

  20. Effect of Silica Fume on two-stage Concrete Strength

    Science.gov (United States)

    Abdelgader, H. S.; El-Baden, A. S.

    2015-11-01

    Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

  1. Preparation and Mechanical Properties of Pressed Straw Concrete Brick

    Science.gov (United States)

    Sumarni, S.; Wijanarko, W.

    2018-03-01

    Rice straws have been widely used as wall filler material in China, Australia, and United States, by spinning them into hays with an approximate dimension of 40 cm of height, 40cm of thickness and 60 cm of width, using a machine. Then, the hays are placed into a wall frame until they fill it completely. After that, the wall frame is covered with wire mesh and plastered. In this research, rice straws are to be used as concrete brick fillers, by pressing the straws into hays and then putting them into the concrete brick mold along with mortar. The objective of this research is to investigate the mechanical properties of concrete brick, namely: compressive strength, specific gravity, and water absorption power. This research used experimental research method. It was conducted by using concrete bricks which had 400 cm of width, 200 cm of height, and 100 cm of thickness, made from rice straws, cement, sand, and water as the test sample. The straws were each made different by their volume. The mortars used in this research were made from cement, sand, and water, with the ratio of 1:7:0.5. The concrete bricks were made by pressing straws mixed with glue into hays, and then cut by determined variations of volume. The variations of hays volume were 0 m3, 0.000625 m3, 0.00075 m3, 0.000875 m3, 0.00125 m3, 0.0015 m3, 0.00175 m3, 0.001875 m3, 0.00225 m3, and 0.002625 m3. There were 3 samples for each volumes of hays. The result shows that the straw concrete bricks reached the maximum compressive strength of 1.92 MPa, specific gravity of 1,702 kg/m3, and water absorption level of 3.9 %. Based on the provided measurements of products in the Standar Nasional Indonesia (Indonesian product standardization), the concrete bricks produced attained the prescribed standard quality.

  2. 7 CFR 58.730 - Filling containers.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Filling containers. 58.730 Section 58.730 Agriculture... Procedures § 58.730 Filling containers. Hot fluid cheese from the cookers may be held in hotwells or hoppers... shall effectively measure the desired amount of product into the pouch or container in a sanitary manner...

  3. Selective filling of Photonic Crystal Fibres

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Noordegraaf, Danny; Sørensen, Thorkild

    2005-01-01

    A model for calculating the time necessary for filling one or more specific holes in a photonic crystal fibre is made. This model is verified for water, and its enabling potential is illustrated by a polymer application. Selective filling of the core in an air-guide photonic crystal fibre...

  4. Current state of knowledge on the behavior of steel liners in concrete containments subjected to overpressurization loads

    International Nuclear Information System (INIS)

    von Riesemann, W.A.; Parks, M.B.

    1993-01-01

    In the United States, concrete containment buildings for commercial nuclear power plants have steel liners that act as the intemal pressure boundary. The liner abuts the concrete, acting as the interior concrete form. The liner is attached to the concrete by either studs or by a continuous structural shape (such as a T-section or channel) that is either continuously or intermittently welded to the liner. Studs are commonly used in reinforced concrete containments, while prestressed containments utilize a structural element as the anchorage. The practice in some countries follows the US practice, while in other countries the containment does not have a steel liner. In this latter case, there is a true double containment, and the annular region between the two containments is vented. This paper will review the practice of design of the liner system prior to the consideration of severe accident loads (overpressurization loads beyond the design conditions)

  5. Raman spectra of filled carbon nanotubes

    International Nuclear Information System (INIS)

    Bose, S.M.; Behera, S.N.; Sarangi, S.N.; Entel, P.

    2004-01-01

    The Raman spectra of a metallic carbon nanotube filled with atoms or molecules have been investigated theoretically. It is found that there will be a three way splitting of the main Raman lines due to the interaction of the nanotube phonon with the collective excitations (plasmons) of the conduction electrons of the nanotube as well as its coupling with the phonon of the filling material. The positions and relative strengths of these Raman peaks depend on the strength of the electron-phonon interaction, phonon frequency of the filling atom and the strength of interaction of the nanotube phonon and the phonon of the filling atoms. Careful experimental studies of the Raman spectra of filled nanotubes should show these three peaks. It is also shown that in a semiconducting nanotube the Raman line will split into two and should be observed experimentally

  6. Use of rubber crumbs in cement concrete

    Science.gov (United States)

    Longvinenko, A. A.

    2018-03-01

    Rubber crumb obtained from worn out tires has been increasingly used over the last 15-20 years, especially in manufacture of asphalt and cement concrete mixtures. This review pays principal attention to application of the rubber crumb to cement concrete mixtures. Use of the rubber crumb in cement concrete is not as successful as in asphalt concrete mixtures, due to incompatibility problems linked to chemical composition and a significant difference in rigidity between the rubber crumb and concrete mixture aggregates. Different methods are proposed and studied to mitigate the adverse influence and increase the beneficial effects of the rubber crumb when added to cement concrete.

  7. A study on sodium-concrete reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jae Heum; Min, Byong Hun [Suwon University, Suwon (Korea, Republic of)

    1997-07-01

    A small sodium-concrete reaction facility was designed, manufactured and installed. this facility has been operated under inert gas(N{sub 2}) with different experimental variables such as sodium injection temperature, injection amount of sodium, aging period of concrete, sodium reservoir temperature. As a result, it was found that sodium injection temperature and injected amount of sodium has little effect on sodium-concrete reaction. However, sodium reservoir temperature and aging period of concrete has relatively high impact on sodium-concrete reaction. Sodium-concrete reaction model has also been developed and compared with experimental results. (Author) 51 refs., 16 tabs., 64 figs.

  8. Large Scale Glazed Concrete Panels

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

    Today, there is a lot of focus on concrete surface’s aesthitic potential, both globally and locally. World famous architects such as Herzog De Meuron, Zaha Hadid, Richard Meyer and David Chippenfield challenge the exposure of concrete in their architecture. At home, this trend can be seen...... in the crinkly façade of DR-Byen (the domicile of the Danish Broadcasting Company) by architect Jean Nouvel and Zaha Hadid’s Ordrupgård’s black curved smooth concrete surfaces. Furthermore, one can point to initiatives such as “Synlig beton” (visible concrete) that can be seen on the website www.......synligbeton.dk and spæncom’s aesthetic relief effects by the designer Line Kramhøft (www.spaencom.com). It is my hope that the research-development project “Lasting large scale glazed concrete formwork,” I am working on at DTU, department of Architectural Engineering will be able to complement these. It is a project where I...

  9. 304 Concretion facility closure plan

    International Nuclear Information System (INIS)

    1990-04-01

    The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium Zircaloy-2 and copper silicon alloy, uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets in the 304 Concretion Facility, located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Concretion Facility (304 Facility). Clean closure of the 304 Facility is the proposed method for closure of the facility. Justification for this proposal is presented. 15 refs., 22 figs., 4 tabs

  10. The Tectonic Potentials of Concrete

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2013-01-01

    Contemporary techniques for concrete casting in an architectural context are challenged by demands of increased individualization in our built environment, reductions in the use of resources and waste generation. In recent years, new production technologies and strategies that break with the indu......Contemporary techniques for concrete casting in an architectural context are challenged by demands of increased individualization in our built environment, reductions in the use of resources and waste generation. In recent years, new production technologies and strategies that break...... with the industrial paradigm of standardization, have been put forward. This development is carried forward by computers and digital fabrication, but has yet to find its way into the production of building components. With regards to concrete casting, however, existing research do offer advancement towards...... an increased customisation of casting moulds. The hypothesis of this research is that the techniques used in this research do not fully address the tectonic potentials of concrete which gives rise to the primary research question: Is it possible to enhance existing or develop new concrete casting techniques...

  11. Nanogranular origin of concrete creep.

    Science.gov (United States)

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-06-30

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate ( approximately 1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years.

  12. Carbonation around near aggregate regions of old hardened concrete cement paste

    International Nuclear Information System (INIS)

    Tam, Vivian W.Y.; Gao, X.F.; Tam, C.M.

    2005-01-01

    Analogous with most modern cities, waste disposal is a pressing issue due to limited landfill and public filling (land reclamation) areas in Hong Kong in which construction and demolition (C and D) waste forms the major source. Concrete, apportioning the largest portion of C and D waste, has the greatest potential for recycling. However, the knowledge on micro-structural behavior of concrete waste is immature to give adequate details on the macro-behavior of concrete waste. This paper attempts to examine the problems of recycling old concrete by investigating the microstructure and phase transformation of the concrete samples collected from buildings with 46 and 37 years of services. From the results of Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) examination, it is found that there are a lot of pores at the near layers of aggregate where carbonation of the hardened cement paste (HCP) is high. The pores may be generated as a result of poor workmanship such as insufficient concrete mixing time, trapping of air voids beneath coarse aggregate, inappropriate water to cement ratio, and the microclimate conditions such as humidity that affects the demand on water from the aggregate during mixing

  13. Mock-up experiments for the project of high dose irradiation on the RPV concrete

    International Nuclear Information System (INIS)

    Zdarek, J.; Brabec, P.; Frybort, O.; Lahodova, Z.; Vit, J.; Stemberk, P.

    2015-01-01

    Aging of NPP's concrete structures comes into growing interest in connection with solution of life extension programmes of operated units. Securing continued safe operation of NPPs calls for additional proofs of suitable long term behaviour of loaded reinforced concrete structures. An irradiation test of concrete samples was performed in the core of the LVR-15 reactor. The irradiation capsule was hung in the irradiation channel and the cooling of the capsule was ensured through direct contact of the capsule wall with the primary circuit water. Cylindrical, serpentine concrete samples (50 mm in diameter and 100 mm in length), representing composition of WWER RPV cavity, was chosen as a compromise of mechanical properties testing needs and dimension limitations of reactor irradiation channel. Heating during irradiation test was maintained under 93 Celsius degrees by cooling and was controlled by embedded thermocouple. Design of the cooling management was supported by computational analysis. The dependencies of heated concrete samples to the neutron fluence and the gamma heating were obtained by changing the thermal power of the reactor and by changing the vertical position of the sample in the irradiation channel. The irradiation capsule was filled with inert gas (helium) to allow the measurement of generated gas. The determination of concrete samples activity for long-term irradiation was performed on the principles of the Neutron Activation Analysis. Preliminary mock-up tests have proved the ability to fulfill technical needs for planned high dose irradiation experiment

  14. Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete

    Directory of Open Access Journals (Sweden)

    Wu-Jian Long

    2014-10-01

    Full Text Available With the extensive use of self-consolidating concrete (SCC worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration.

  15. Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete.

    Science.gov (United States)

    Long, Wu-Jian; Khayat, Kamal Henri; Lemieux, Guillaume; Hwang, Soo-Duck; Xing, Feng

    2014-10-10

    With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration.

  16. HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

    Directory of Open Access Journals (Sweden)

    O. M. Pshinko

    2015-08-01

    Full Text Available Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic–viscous–plastic bodies. The system of canonical equations consists of the equations for concrete strength, absolute volume, concrete mix consistency as well as the equation for optimal concrete saturation with aggregates while minimizing cement content. The joint solution of these four equations related to composition allows determining for the materials the concrete composition of required strength, concrete workability with minimum cement content. The procedure for calculation of hydraulic concrete composition according to the physico-analytical method consists of two parts: 1 physical, which is laboratory testing of concrete mix components in different concrete compositions; 2 analytical, which represents the calculation algorithm for concrete compositions equivalent in concrete strength and workability that comply with the specific conditions of concrete placing. Findings. To solve the problem of designing the concrete composition with the desired properties for railway structures and buildings it was proposed to use the information technology in the form of a developed computer program whose algorithm includes the physico-analytical method for hydraulic concrete composition determination. Originality. The developed concrete composition design method takes into account the basic properties of raw materials, concrete mix and concrete, which are pre-determined. The distinctive feature of physico-analytical method is obtaining of a set of equivalent compositions with a certain concrete mix

  17. Bending characteristics of resin concretes

    Directory of Open Access Journals (Sweden)

    Ribeiro Maria Cristina Santos

    2003-01-01

    Full Text Available In this research work the influence of composition and curing conditions in bending strength of polyester and epoxy concrete is analyzed. Various mixtures of resin and aggregates were considered in view of an optimal combination. The Taguchi methodology was applied in order to reduce the number of tests, and in order to evaluate the influence of various parameters in concrete properties. This methodology is very useful for the planning of experiments. Test results, analyzed by this methodology, shown that the most significant factors affecting bending strength properties of resin concretes are the type of resin, resin content and charge content. An optimal formulation leading to a maximum bending strength was achieved in terms of material parameters.

  18. The bacterial corrosion of concretes

    International Nuclear Information System (INIS)

    Tache, G.

    1998-01-01

    Concrete is a material very sensitive to aging effects and to permanent aggressions. It is an evolutive material in which internal hydration reactions and exchange reactions with the external medium are produced. Moreover, its characteristics tightly depends on factors which are bound to its formulation, to the appropriate choice of materials in which it is constituted, to their qualities and to the conditions of its use. Its aging depends then in a large extent of these different factors and of the adequation between its final characteristics and the solicitations in which it is submitted: physical, mechanical, thermal.. or environmental. This chapter deals particularly with the influence of the bacterial phenomena on concrete. Some recalls are at first given on the principles which govern the concrete durability. Then are approached the phenomena mechanisms. (O.M.)

  19. The Tectonic Potentials of Concrete

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2013-01-01

    . However, a single concrete casting material, given the use of the right technique that is able to address all these problems, has not been identified, neither in state-of-the-art nor in the case studies. It follows that due to today’s demands for resource optimization and competitiveness it is unlikely......Contemporary techniques for concrete casting in an architectural context are challenged by demands of increased individualization in our built environment, reductions in the use of resources and waste generation. In recent years, new production technologies and strategies that break...... with the industrial paradigm of standardization, have been put forward. This development is carried forward by computers and digital fabrication, but has yet to find its way into the production of building components. With regards to concrete casting, however, existing research do offer advancement towards...

  20. Design of buried concrete encasements

    International Nuclear Information System (INIS)

    Drake, R.M.

    1989-01-01

    The operation of many Department of Energy (DOE) sites requires the transfer of radioactive liquid products from one location to another. DOE Order 6430.1A requires that the transfer pipelines be designed and constructed so that any leakage can be detected and contained before it reaches the environment. One design option often considered to meet this requirement is to place the pipeline in a stainless steel-lined, buried concrete encasement. This provides the engineer with the design challenge to integrate standard structural design principles with unique DOE requirements. The complete design of a buried concrete encasement must consider seismic effects, leak detection, leak confinement, radiation shielding, thermal effects, pipe supports, and constructability. This paper contains a brief discussion of each of these design considerations, based on experience gained during the design of concrete encasements for the Process Facilities Modifications (PFM) project at Hanford

  1. Effect of Penetron Admix on the Properties of Concrete

    African Journals Online (AJOL)

    2012r

    2014-07-02

    Jul 2, 2014 ... reducing the emission of greenhouse gases and in increasing the life cycle of concrete structures ..... Reuse of Concrete Block Debris in Concrete. Dissertation (BEng). ... Use of Recycled Concrete Aggregate in. Structural ...

  2. Design of Ultra High Performance Fiber Reinforced Concrete Shells

    DEFF Research Database (Denmark)

    Jepsen, Michael S.; Lambertsen, Søren Heide; Damkilde, Lars

    2013-01-01

    Fiber Reinforced Concrete shell. The major challenge in the design phase has been securing sufficient stiffness of the structure while keeping the weight at a minimum. The weight/stiffness issue has been investigated by means of the finite element method, to optimize the structure regarding overall......The paper treats the redesign of the float structure of the Wavestar wave energy converter. Previously it was designed as a glass fiber structure, but due to cost reduction requirements a redesign has been initiated. The new float structure will be designed as a double curved Ultra High Performance...

  3. Double inflation

    International Nuclear Information System (INIS)

    Silk, J.; Turner, M.S.

    1986-04-01

    The Zel'dovich spectrum of adiabatic density perturbations is a generic prediction of inflation. There is increasing evidence that when the spectrum is normalized by observational data on small scales, there is not enough power on large scales to account for the observed large-scale structure in the Universe. Decoupling the spectrum on large and small scales could solve this problem. As a means of decoupling the large and small scales we propose double inflation (i.e., two episodes of inflation). In this scenario the spectrum on large scales is determined by the first episode of inflation and those on small scales by a second episode of inflation. We present three models for such a scenario. By nearly saturating the large angular-scale cosmic microwave anisotropy bound, we can easily account for the observed large-scale structure. We take the perturbations on small scales to be very large, deltarho/rho approx. = 0.1 to 0.01, which results in the production of primordial black holes (PBHs), early formation of structure, reionization of the Universe, and a rich array of astrophysical events. The Ω-problem is also addressed by our scenario. Allowing the density perturbations produced by the second episode of inflation to be large also lessens the fine-tuning required in the scalar potential and makes reheating much easier. We briefly speculate on the possibility that the second episode of inflation proceeds through the nucleation of bubbles, which today manifest themselves as empty bubbles whose surfaces are covered with galaxies. 37 refs., 1 fig

  4. Neutron diffraction and thermoelectric properties of indium filled In{sub x}Co{sub 4}Sb{sub 12} (x = 0.05, 0.2) and indium cerium filled Ce{sub 0.05}In{sub 0.1}Co{sub 4}Sb{sub 12} skutterudites

    Energy Technology Data Exchange (ETDEWEB)

    Sesselmann, Andreas [Institute of Materials Research, German Aerospace Center (DLR), Linder Hoehe, 51147 Koeln (Germany); Klobes, Benedikt [Juelich Centre for Neutron Science JCNS und Peter Gruenberg Institute PGI, JARA-FIT, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Dasgupta, Titas [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology, Mumbai (India); Gourdon, Olivier [Los Alamos National Laboratory, LANSCE, Los Alamos, New Mexico 87545 (United States); Hermann, Raphael [Juelich Centre for Neutron Science JCNS und Peter Gruenberg Institute PGI, JARA-FIT, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Faculte des Sciences, Universite de Liege, 4000 Liege (Belgium); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Mueller, Eckhard [Institute of Materials Research, German Aerospace Center (DLR), Linder Hoehe, 51147 Koeln (Germany); Institute of Inorganic and Analytical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 58, 35392 Giessen (Germany)

    2016-03-15

    The thermoelectric properties on polycrystalline single (In) and double filled (Ce, In) skutterudites are characterized between 300 and 700 K. Powder neutron diffraction measurements of the skutterudite compositions In{sub x}Co{sub 4}Sb{sub 12} (x = 0.05, 0.2) and Ce{sub 0.05}In{sub 0.1}Co{sub 4}Sb{sub 12} as a function of temperature (12-300 K) were carried out, which gives more insight into the structural data of single and double-filled skutterudites. Results show that due to the annealing treatment, a Sb deficiency is detectable and thus verifies defects at the Sb lattice site of the skutterudite. Furthermore, we show by electron microprobe analysis that a considerable amount of indium is lost during synthesis and post-processing for the single indium filled samples, but not for the double cerium and indium skutterudite sample. In our experiments, the double-filled skutterudite is superior to the single-filled skutterudite composition due to a higher charge carrier density, a comparable lattice thermal resistivity, and a higher density of states effective mass. Furthermore, we obtained a significantly higher Einstein temperature for the double-filled skutterudite composition in comparison to the single-filled species, which reflects the high sensitivity due to filling of the void lattice position within the skutterudite crystal. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Reliability Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Middleton, C. R.

    This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the details of a methodology which can be used to generate Whole Life (WL) reliability...... profiles. These WL reliability profiles may be used to establish revised rules for concrete bridges. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

  6. A Failure Criterion for Concrete

    DEFF Research Database (Denmark)

    Ottosen, N. S.

    1977-01-01

    A four-parameter failure criterion containing all the three stress invariants explicitly is proposed for short-time loading of concrete. It corresponds to a smooth convex failure surface with curved meridians, which open in the negative direction of the hydrostatic axis, and the trace in the devi......A four-parameter failure criterion containing all the three stress invariants explicitly is proposed for short-time loading of concrete. It corresponds to a smooth convex failure surface with curved meridians, which open in the negative direction of the hydrostatic axis, and the trace...

  7. Concrete structures under projectile impact

    CERN Document Server

    Fang, Qin

    2017-01-01

    In this book, the authors present their theoretical, experimental and numerical investigations into concrete structures subjected to projectile and aircraft impacts in recent years. Innovative approaches to analyze the rigid, mass abrasive and eroding projectile penetration and perforation are proposed. Damage and failure analyses of nuclear power plant containments impacted by large commercial aircrafts are numerically and experimentally analyzed. Ultra-high performance concrete materials and structures against the projectile impact are developed and their capacities of resisting projectile impact are evaluated. This book is written for the researchers, engineers and graduate students in the fields of protective structures and terminal ballistics.

  8. Quality assurance of polymer concrete

    International Nuclear Information System (INIS)

    Schulz, H.

    1984-01-01

    With polymer concrete, a whole range of organisational and functional measures have to be met in order to assure the required quality with an economic expenditure. Quality assurance begins in the design and does not end in the production, rather includes all fields of the enterprise. The following deals with a particular range of the total complex, the inspection methods for assuring the quality of machine components of polymer concrete, particularly machine tool bases, this being through the control of the raw material, the production and the finished product. (orig.) [de

  9. The steel–concrete interface

    DEFF Research Database (Denmark)

    Angst, Ueli M.; Geiker, Mette Rica; Michel, Alexander

    2017-01-01

    Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics....... It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between...

  10. Construction of concrete hot cells

    International Nuclear Information System (INIS)

    1981-12-01

    The standard is to be applied to rooms (hot cells) which are enclosed by a concrete shield and in which radioactive material is handled by remote control. The rooms may be in facilities for experimental purposes (e.g. development of fuel elements and materials or of chemical processes) or in facilities for production purposes (e.g. reprocessing of nuclear fuel or treatment of radioactive wastes). The standard is to give a design hasis for concrete hot cells and their installations which is to be applied by designers, constructors, future users and competent authorities as well as independent experts. (orig.) [de

  11. Construction of concrete hot cells

    International Nuclear Information System (INIS)

    1980-09-01

    The standard is to be applied to rooms (hot cells) which are enclosed by a concrete shield and in which radioactive material is handled by remote control. The rooms may be in facilities for experimental purposes (e.g. development of fuel elements and materials or of chemical processes) or in facilities for production purposes (e.g. reprocessing of nuclear fuel or treatment of radioactive wastes). The standard is to give a design basis for concrete hot cells and their installations which is to be applied by designers, constructors, future users and competent authorities as well as independent experts. (orig.) [de

  12. Double Outlet Right Ventricle

    Science.gov (United States)

    ... Right Ventricle Menu Topics Topics FAQs Double Outlet Right Ventricle Double outlet right ventricle (DORV) is a rare form of congenital heart disease. En español Double outlet right ventricle (DORV) is a rare form of congenital ...

  13. Surface Chloride Levels in Colorado Structural Concrete

    Science.gov (United States)

    2018-01-01

    This project focused on the chloride-induced corrosion of reinforcing steel in structural concrete. The primary goal of this project is to analyze the surface chloride concentration level of the concrete bridge decks throughout Colorado. The study in...

  14. Modeling damage in concrete pavements and bridges.

    Science.gov (United States)

    2010-09-01

    This project focused on micromechanical modeling of damage in concrete under general, multi-axial loading. A : continuum-level, three-dimensional constitutive model based on micromechanics was developed. The model : accounts for damage in concrete by...

  15. Advances in the material science of concrete

    National Research Council Canada - National Science Library

    Ideker, Jason H; Radlinska, Aleksandra

    2010-01-01

    ... Committee 236, Material Science of Concrete. The session focused on material science aspects of concrete with an emphasis placed on advances in understanding the fundamental scientific topics of cement-based materials, as well as the crucial...

  16. Long-life slab replacement concrete.

    Science.gov (United States)

    2015-03-01

    This research was initiated following reports of high incidence of cracking on FDOT concrete pavement replacement : slab projects. Field slabs were instrumented for data acquisition from high-early-strength concrete pavement : replacement slabs place...

  17. Recycled materials in Portland cement concrete

    Science.gov (United States)

    2000-06-01

    This report pertains to a comprehensive study involving the use of recycled materials in Portland cement concrete. Three different materials were studied including crushed glass (CG), street sweepings (SS), and recycled concrete (RC). Blast furnace s...

  18. Concrete performance using low-degradation aggregates.

    Science.gov (United States)

    2012-06-01

    The durability of Portland cement concrete (PCC) has long been identified as a concern by transportation communities around the United States. In this study, the long-term performance of two batches of concrete incorporating either low-degradation (L...

  19. Influence of processing factors over concrete strength.

    Science.gov (United States)

    Kara, K. A.; Dolzhenko, A. V.; Zharikov, I. S.

    2018-03-01

    Construction of facilities of cast in-situ reinforced concrete poses additional requirements to quality of material, peculiarities of the construction process may sometimes lead to appearance of lamination planes and inhomogeneity of concrete, which reduce strength of the material and structure as a whole. Technology compliance while working with cast in-situ concrete has a significant impact onto the concrete strength. Such process factors as concrete curing, vibration and compaction of the concrete mixture, temperature treatment, etc., when they are countered or inadequately followed lead to a significant reduction in concrete strength. Here, the authors experimentally quantitatively determine the loss of strength in in-situ cast concrete structures due to inadequate following of process requirements, in comparison with full compliance.

  20. Softening behaviour of concrete : numerical research

    NARCIS (Netherlands)

    Bongers, J.P.W.; Rutten, H.S.; Fijneman, H.J.

    1994-01-01

    Experimental research shows, apart from the influence of multiaxial loading conditions, that softening of concrete loaded in compression is accompanied by localization of deformations. Therefore, numerical modelling of concrete material behaviour has to take this effect into account. This implies