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Sample records for high compressive strength

  1. Strength Regularity and Failure Criterion of High-Strength High-Performance Concrete under Multiaxial Compression

    Institute of Scientific and Technical Information of China (English)

    HE Zhen-jun; SONG Yu-pu

    2008-01-01

    Multiaxial compression tests were performed on 100 mm × 100 mm × 100 nun high-strength high-performance concrete (HSHPC) cubes and normal strength concrete (NSC) cubes. The failure modes of specimens were presented, the static compressive strengths in principal directions were measured, the influence of the stress ratios was analyzed. The experimental results show that the ultimate strengths for HSHPC and NSC under multiaxial compression are greater than the uniaxial compressive strengths at all stress ratios, and the multiaxial strength is dependent on the brittleness and stiffness of concrete, the stress state and the stress ratios. In addition, the Kupfer-Gerstle and Ottosen's failure criteria for plain HSHPC and NSC under multiaxial compressive loading were modified.

  2. TRIAXIAL COMPRESSIVE STRENGTH OF ULTRA HIGH PERFORMANCE CONCRETE

    Directory of Open Access Journals (Sweden)

    Radoslav Sovják

    2013-12-01

    Full Text Available The aim of this work is to describe the strength of Ultra High Performance Concrete (UHPC under triaxial compression. The main goal is to find a trend in the triaxial compressive strength development under various values of confinement pressure. The importance of triaxial tests lies in the spatial loading of the sample, which simulates the real loading of the material in the structure better than conventional uniaxial strength tests. In addition, the authors describe a formulation process for UHPC that has been developed without using heat treatment, pressure or a special mixer. Only ordinary materials available commercially in the Czech Republic were utilized throughout the material design process.

  3. Design of High Compressive Strength Concrete Mix without Additives

    Directory of Open Access Journals (Sweden)

    Akasha, N, M

    2017-02-01

    Full Text Available In this paper, the crashed Basalt and uncrushed granite is used in concrete mixes as coarse aggregate. The selected materials, with high specification using special production techniques, the properties ,the mix design procedure and mix proportion of the high strength concrete (HSC were discussed. Different proportions of Ordinary Portland cement (410,430 and 450 kg/m3 with different crashed Basalt and uncrushed Granite coarse aggregate amount (1120 and 1050 kg/m3 and fine aggregate with fine modulus of 3.65 were used. Eight concrete mixes were prepared: two as control mix for crashed Basalt and uncrushed Granite, three with crashed Basalt and three with uncrushed Granite coarse aggregate with mix amount(410:680:1120,430:610:1050 and 450:550:1050 kg/m3,(cement: fine aggregate: coarse aggregaterespectively. The study showed that the use of granite coarse aggregate in concrete mixes has a clear effect in mix proportion. The compressive strength of concrete was measured at ages of 7, 28 and 56 days and it was found that the granite (Mix3 of (450:550:1050 kg/m3 with w/c of 0.46 give the highest of strength in 28 and 56 days among the abovementioned mixes its 56 and 64 N/mm2 respectively. The paper shows that good results of compressive strength and workability of concrete were obtained when using granite coarse aggregate.

  4. Compressive mechanical of high strength concrete (HSC) after different high temperature history

    Science.gov (United States)

    Zhao, Dongfu; Liu, Yuchen; Gao, Haijing; Han, Xiao

    2017-08-01

    The compression strength test of high strength concrete under different high-temperature conditions was carried out by universal testing machine. The friction surface of the pressure bearing surface of the specimen was composed of three layers of plastic film and glycerol. The high temperature working conditions were the combination of different heating temperature and different constant temperature time. The characteristics of failure modes and the developments of cracks were observed; the residual compressive strength and stress-strain curves were measured; the effect of different temperature and heating time on the strength and deformation of high strength concrete under uniaxial compression were analyzed; the failure criterion formula of the high strength concrete after high temperature under uniaxial compression was established. The formula of the residual compressive strength of high strength concrete under the influence of heating temperature and constant temperature time was put forward. The relationship between the residual elastic modulus and the peak strain and residual compressive strength of high strength concrete and different high temperature conditions is established. The quantitative relationship that the residual compressive strength decreases the residual elastic modulus decreases and the peak strain increases with the increase of heating temperature and the constant temperature time was given, which provides a reference for the detection and evaluation of high strength concrete structures after fire.

  5. Effect of Curing Temperature Histories on the Compressive Strength Development of High-Strength Concrete

    Directory of Open Access Journals (Sweden)

    Keun-Hyeok Yang

    2015-01-01

    Full Text Available This study examined the relative strength-maturity relationship of high-strength concrete (HSC specifically developed for nuclear facility structures while considering the economic efficiency and durability of the concrete. Two types of mixture proportions with water-to-binder ratios of 0.4 and 0.28 were tested under different temperature histories including (1 isothermal curing conditions of 5°C, 20°C, and 40°C and (2 terraced temperature histories of 20°C for an initial age of individual 1, 3, or 7 days and a constant temperature of 5°C for the subsequent ages. On the basis of the test results, the traditional maturity function of an equivalent age was modified to consider the offset maturity and the insignificance of subsequent curing temperature after an age of 3 days on later strength of concrete. To determine the key parameters in the maturity function, the setting behavior, apparent activation energy, and rate constant of the prepared mixtures were also measured. This study reveals that the compressive strength development of HSC cured at the reference temperature for an early age of 3 days is insignificantly affected by the subsequent curing temperature histories. The proposed maturity approach with the modified equivalent age accurately predicts the strength development of HSC.

  6. Development of K-Basin High-Strength Homogeneous Sludge Simulants and Correlations Between Unconfined Compressive Strength and Shear Strength

    Energy Technology Data Exchange (ETDEWEB)

    Onishi, Yasuo; Baer, Ellen BK; Chun, Jaehun; Yokuda, Satoru T.; Schmidt, Andrew J.; Sande, Susan; Buchmiller, William C.

    2011-02-20

    K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and

  7. Fracture Energy of High-Strength Concrete in Compression

    DEFF Research Database (Denmark)

    Dahl, H.; Brincker, Rune

    1989-01-01

    is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical properties of concrete in compression. Including the measurement and study of the descending branch, a new experimental...

  8. Fatigue of concrete under compression: Database and proposal for high strength concrete

    NARCIS (Netherlands)

    Lantsoght, E.O.L.

    2014-01-01

    The compressive strength of concrete decreases as an element is subjected to cycles of loading. In a typical fatigue test for the concrete compressive strength, a concrete specimen (typically a cylinder) is loaded between a lower and upper stress limit. These limits are expressed as a fraction of th

  9. Fatigue of concrete under compression: Database and proposal for high strength concrete

    NARCIS (Netherlands)

    Lantsoght, E.O.L.

    2014-01-01

    The compressive strength of concrete decreases as an element is subjected to cycles of loading. In a typical fatigue test for the concrete compressive strength, a concrete specimen (typically a cylinder) is loaded between a lower and upper stress limit. These limits are expressed as a fraction of

  10. The Effects of Design Strength, Fly Ash Content and Curing Method on Compressive Strength of High Volume Fly Ash Concrete: A Design of Experimental

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    Solikin Mochamad

    2017-01-01

    Full Text Available High volume fly ash concrete becomes one of alternatives to produce green concrete as it uses waste material and significantly reduces the utilization of Portland cement in concrete production. Although using less cement, its compressive strength is comparable to ordinary Portland cement (hereafter OPC and the its durability increases significantly. This paper reports investigation on the effect of design strength, fly ash content and curing method on compressive strength of High Volume Fly Ash Concrete. The experiment and data analysis were prepared using minitab, a statistic software for design of experimental. The specimens were concrete cylinder with diameter of 15 cm and height of 30 cm, tested for its compressive strength at 56 days. The result of the research demonstrates that high volume fly ash concrete can produce comparable compressive strength which meets the strength of OPC design strength especially for high strength concrete. In addition, the best mix proportion to achieve the design strength is the combination of high strength concrete and 50% content of fly ash. Moreover, the use of spraying method for curing method of concrete on site is still recommended as it would not significantly reduce the compressive strength result.

  11. The Compressive Strength of High-Performance Concrete and Ultrahigh-Performance

    Directory of Open Access Journals (Sweden)

    E. H. Kadri

    2012-01-01

    Full Text Available The compressive strength of silica fume concretes was investigated at low water-cementitious materials ratios with a naphthalene sulphonate superplasticizer. The results show that partial cement replacement up to 20% produce, higher compressive strengths than control concretes, nevertheless the strength gain is less than 15%. In this paper we propose a model to evaluate the compressive strength of silica fume concrete at any time. The model is related to the water-cementitious materials and silica-cement ratios. Taking into account the author's and other researchers’ experimental data, the accuracy of the proposed model is better than 5%.

  12. Prediction of compression strength of high performance concrete using artificial neural networks

    Science.gov (United States)

    Torre, A.; Garcia, F.; Moromi, I.; Espinoza, P.; Acuña, L.

    2015-01-01

    High-strength concrete is undoubtedly one of the most innovative materials in construction. Its manufacture is simple and is carried out starting from essential components (water, cement, fine and aggregates) and a number of additives. Their proportions have a high influence on the final strength of the product. This relations do not seem to follow a mathematical formula and yet their knowledge is crucial to optimize the quantities of raw materials used in the manufacture of concrete. Of all mechanical properties, concrete compressive strength at 28 days is most often used for quality control. Therefore, it would be important to have a tool to numerically model such relationships, even before processing. In this aspect, artificial neural networks have proven to be a powerful modeling tool especially when obtaining a result with higher reliability than knowledge of the relationships between the variables involved in the process. This research has designed an artificial neural network to model the compressive strength of concrete based on their manufacturing parameters, obtaining correlations of the order of 0.94.

  13. Research on compressive strength of recycled cement mortar after high temperature

    Science.gov (United States)

    Zhang, Xianggang; Yang, Jianhui; Deng, Dapeng

    2017-01-01

    In order to study cube compressive strength of recycled fine aggregate cement mortar after different temperatures, with the affect parameters between replacement rate of recycled fine aggregate and temperature, 45 standard cube test blocks were designed and produced to carry out compressive strength test. The failure process and failure mode of test blocks were observed. Ultimate compressive strength of cube blocks were measured, the relations between cube compressive strength and the replacement rates of recycled fine aggregate under different temperatures as well as the relations between cube compressive strength and temperatures under different replacement rates were all analyzed, the influence change parameters made on cube compressive strength was discussed. The results showed: the failure process and the failure mode of recycled fine aggregate cement mortar and the failure process and the failure mode of nature is similar; when the temperature reached 400°C, the block has no burst phenomenon, but the colour of block into a dark pink; with the increase of recycled fine aggregate, the mass lose rate of block is increase; effect different temperature make on cube compressive strength of test block is not obvious when temperature keeps same for 3h.

  14. A Study of the Efficiency of High-strength, Steel, Cellular-core Sandwich Plates in Compression

    Science.gov (United States)

    Johnson, Aldie E , Jr; Semonian, Joseph W

    1956-01-01

    Structural efficiency curves are presented for high-strength, stainless-steel, cellular-core sandwich plates of various proportions subjected to compressive end loads for temperatures of 80 F and 600 F. Optimum proportions of sandwich plates for any value of the compressive loading intensity can be determined from the curves. The efficiency of steel sandwich plates of optimum proportions is compared with the efficiency of solid plates of high-strength steel and aluminum and titanium alloys at the two temperatures.

  15. Influence of curing regimes on compressive strength of ultra high performance concrete

    Indian Academy of Sciences (India)

    Prabhat Ranjan Prem; B H Bharatkumar; Nagesh R Iyer

    2013-12-01

    The present paper is aimed to identify an efficient curing regime for ultra high performance concrete (UHPC), to achieve a target compressive strength more than 150 MPa, using indigenous materials. The thermal regime plays a vital role due to the limited fineness of ingredients and low water/binder ratio. By activation of the reaction kinetics, the effectiveness of the binder is enhanced which leads to improvements in mechanical as well as durability properties. The curing cycle employed are ambient air curing, water curing and hot air curing. The specimens were exposed to thermal regime at (90°C/150°C/200°C) for duration of 24, 48 or 72 hours at the age of 3rd and 7th day followed with air curing or water curing till 28 days. The results showed a marked difference in compressive strength ranging from 217 to 142 MPa with change in curing regimes. The samples when thermally cured at the age of 3rd and 7th day produced an average ultimate strength of 217–152 MPa and 196–150 MPa, respectively.

  16. Development of ultra-lightweight slurries with high compressive strength for use in oil wells

    Energy Technology Data Exchange (ETDEWEB)

    Suzart, J. Walter P. [Halliburton Company, Houston, TX (United States); Farias, A.C. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil); Ribeiro, Danilo; Fernandes, Thiago; Santos, Reened [Halliburton Energy Services Aberdeen, Scotland (United Kingdom)

    2008-07-01

    Formations with low fracture gradients or depleted reservoirs often lead to difficult oil well cementing operations. Commonly employed cement slurries (14.0 to 15.8 lb/gal), generate an equivalent circulating density (ECD) higher than the fracture gradient and ultimately lead to formation damage, lost circulation and a decreased top of cement. Given the high price of oil, companies are investing in those and other wells that are difficult to explore. Naturally, lightweight cement slurries are used to reduce the ECD (10.0 to 14.0 lb/gal), using additives to trap water and stabilize the slurry. However, when the density reaches 11.0 lb/gal, the increase in water content may cause a change in characteristics. The focus of this study is extreme cases where it is necessary to employ ultra-lightweight cement slurries (5.5 to 10.0 lb/gal). Foamed slurries have been widely used, and the objective is to set an alternative by developing cement slurries containing uncompressible microspheres, aiming for a density of 7.5 lb/gal as well as high compressive strength. Another benefit in contrast to preparing foamed cement slurries is that there is no requirement for special equipment in the field. Routine laboratory tests such as fluid-loss control, sedimentation, thickening time, free water, compressive strength, and rheology (at room and high temperatures) were performed. Thus, it was concluded that the proposed cement slurries can be used in oil wells. (author)

  17. In-Situ Welding Carbon Nanotubes into a Porous Solid with Super-High Compressive Strength and Fatigue Resistance

    OpenAIRE

    2015-01-01

    Carbon nanotube (CNT) and graphene-based sponges and aerogels have an isotropic porous structure and their mechanical strength and stability are relatively lower. Here, we present a junction-welding approach to fabricate porous CNT solids in which all CNTs are coated and welded in situ by an amorphous carbon layer, forming an integral three-dimensional scaffold with fixed joints. The resulting CNT solids are robust, yet still highly porous and compressible, with compressive strengths up to 72...

  18. Compressive Strength of Hydrostatic-Stress-Sensitive Materials at High Strain-Rates

    Institute of Scientific and Technical Information of China (English)

    LI Q M; LU Y B

    2008-01-01

    Many engineering materials demonstrate dynamic enhancement of their compressive strength with the increase of strain-rate.which have been included in material models to improve the reliability of numerical Simulations of the material and structural responses Under impact and biasl tcads,The strain-rate effects on the dynamic Compressive strength of a range of engineering materials which behave in hydrostatic-stress-sensitive manner were investigated.It is concluded that the dynamic enhancement of the compressive strength of a hydrostatic-stress-sensitive material may include inertia-induced lateral confinement effects,which,as a non-strain-rate factor,may greatly enhance the compressive strength of these materials.Some empirical formulae based on the dynamic stress-strain measurements over-predict the strain-rate effects on the compressive strength of these hydrostatic-stress-sensitive materials,and thus may over-estimate the structural resistance to impact and blast lgads.leading fo non-conservative design of protective structures.

  19. Compressive and flexural strength of expanded perlite aggregate mortar subjected to high temperatures

    Science.gov (United States)

    Zulkifeli, Muhamad Faqrul Hisham bin Mohd; Saman@Hj Mohamed, Hamidah binti Mohd

    2017-08-01

    Work on thermal resistant of outer structures of buildings is one of the solution to reduce death, damages and properties loss in fire cases. Structures protected with thermal resistant materials can delay or avoid failure and collapse during fire. Hence, establishment of skin cladding with advance materials to protect the structure of buildings is a necessary action. Expanded perlite is a good insulation material which can be used as aggregate replacement in mortar. This study is to study on mortar mechanical properties of flexural and compressive strength subjected to elevated temperatures using expanded perlite aggregate (EPA). This study involved experimental work which was developing mortar with sand replacement by volume of 0%, 10%, 20%, 30% and 40% of EPA and cured for 56 days. The mortars then exposed to 200°C, 400 °C, 700 °C and 1000 °C. Flexural and compressive strength of the mortar were tested. The tests showed that there were increased of flexural and compressive strength at 200°C, and constantly decreased when subjected to 400°C, 700°C and 1000 °C. There were also variation of strengths at different percentages of EPA replacement. Highest compressive strength and flexural strength recorded were both at 200 °C with 65.52 MPa and 21.34 MPa respectively. The study conclude that by using EPA as aggregate replacement was ineffective below elevated temperatures but increased the performance of the mortar at elevated temperatures.

  20. In-Situ Welding Carbon Nanotubes into a Porous Solid with Super-High Compressive Strength and Fatigue Resistance

    Science.gov (United States)

    Lin, Zhiqiang; Gui, Xuchun; Gan, Qiming; Chen, Wenjun; Cheng, Xiaoping; Liu, Ming; Zhu, Yuan; Yang, Yanbing; Cao, Anyuan; Tang, Zikang

    2015-06-01

    Carbon nanotube (CNT) and graphene-based sponges and aerogels have an isotropic porous structure and their mechanical strength and stability are relatively lower. Here, we present a junction-welding approach to fabricate porous CNT solids in which all CNTs are coated and welded in situ by an amorphous carbon layer, forming an integral three-dimensional scaffold with fixed joints. The resulting CNT solids are robust, yet still highly porous and compressible, with compressive strengths up to 72 MPa, flexural strengths up to 33 MPa, and fatigue resistance (recovery after 100,000 large-strain compression cycles at high frequency). Significant enhancement of mechanical properties is attributed to the welding-induced interconnection and reinforcement of structural units, and synergistic effects stemming from the core-shell microstructures consisting of a flexible CNT framework and a rigid amorphous carbon shell. Our results provide a simple and effective method to manufacture high-strength porous materials by nanoscale welding.

  1. STRUCTURAL ASPECTS OF PLASTICITY LOWERING OF HIGH-STRENGTH WIRE AT BIG CUMULATIVE COMPRESSIONS

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    V. P. Fetisov

    2012-01-01

    Full Text Available It is shown that decrease of plasticity of high-strength wire at big total cobbings is connected with reduction of mobility of dislocations in the substructure formed at loss of perlite lamellar structure.

  2. Neural network modeling to evaluate the dynamic flow stress of high strength armor steels under high strain rate compression

    Institute of Scientific and Technical Information of China (English)

    Ravindranadh BOBBILI; V. MADHU; A.K. GOGIA

    2014-01-01

    An artificial neural network (ANN) constitutive model is developed for high strength armor steel tempered at 500 ?C, 600 ?C and 650 ?C based on high strain rate data generated from split Hopkinson pressure bar (SHPB) experiments. A new neural network configuration consisting of both training and validation is effectively employed to predict flow stress. Tempering temperature, strain rate and strain are considered as inputs, whereas flow stress is taken as output of the neural network. A comparative study on JohnsoneCook (JeC) model and neural network model is performed. It was observed that the developed neural network model could predict flow stress under various strain rates and tempering temperatures. The experimental stressestrain data obtained from high strain rate compression tests using SHPB, over a range of tempering temperatures (500e650 ?C), strains (0.05e0.2) and strain rates (1000e5500/s) are employed to formulate JeC model to predict the high strain rate deformation behavior of high strength armor steels. The J-C model and the back-propagation ANN model were developed to predict the high strain rate deformation behavior of high strength armor steel and their predictability is evaluated in terms of correlation coefficient (R) and average absolute relative error (AARE). R and AARE for the JeC model are found to be 0.7461 and 27.624%, respectively, while R and AARE for the ANN model are 0.9995 and 2.58%, respectively. It was observed that the predictions by ANN model are in consistence with the experimental data for all tempering temperatures.

  3. Effect of high temperature curing on the compressive strength of concrete incorporating large volumes of fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Villarreal, R. [Universidad Autonoma de Nuevo Leon, Monterrey (Mexico)

    2001-07-01

    The effect of using different types of heat treatment on the compressive strength of concrete with and without large volumes of fly ash was studied. Curing of concrete is important to obtain a good quality concrete, but it is important to keep concrete from drying until the originally water-filled space in fresh cement paste has been filled to the desired extent by the products of hydration. In hot weather, high temperature promotes faster drying of concrete so a given degree of hydration is reached more rapidly than at lower temperatures. The provision of moist curing is advantageous because of a gradual gain in strength and because of reduced plastic shrinkage and drying shrinkage-cracking. The portland cement content in all the mixtures used in this study was 200 kg per cubic metre and the amount of fly ash varied from 0 to 33, 43, 50 and 56 per cent by mass of the total binder. A superplasticizer was used to obtain 200-220 mm slump. The compressive strength was tested at 3, 7, 14, 28, 56 days and at 6 months. Results showed that, using ASTM standard curing, the compressive strength of portland cement concrete made at 35 degrees C was reduced by about 12 per cent at 28 days compared to that of the concrete made at 23 degrees C. The AASHTO curing strength was found to be a bit higher than with the ASTM curing. The concrete made at 35 degrees C showed no loss of strength when continuous moist-curing was applied. The fly ash concrete mixtures that were cast at 35 degrees C were cured by covering them with membrane curing compounds and placed under ambient conditions. It was crucial to allow enough curing water to promote the pozzolanic reaction. The membrane curing did not allow the ingress of water to the concrete mass. 6 refs., 4 tabs., 13 figs.

  4. FAILURE MODE AND CONSTITUTIVE MODEL OF PLAIN HIGH-STRENGTH HIGH-PERFORMANCE CONCRETE UNDER BIAXIAL COMPRESSION AFTER EXPOSURE TO HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    Zhenjun He; Yupu Song

    2008-01-01

    An orthotropic constitutive relationship with temperature parameters for plain highstrength high-performance concrete (HSHPC) under biaxial compression is developed. It is based on the experiments performed for characterizing the strength and deformation behavior at two strength levels of HSHPC at 7 different stress ratios including α = σ2 : σ3 = 0.00 : -1, -0.20 : -1, -0.30 : -1, -0.40 : -1, -0.50 : -1, -0.75 : -1, -1.00 : -1, after the exposure to normal and high temperatures of 20, 200, 300, 400, 500 and 600℃, and using a large static-dynamic true triaxial machine. The biaxial tests were performed on 100 mm × 100 mm × 100 mm cubic specimens, and friction-reducing pads were used consisting of three layers of plastic membrane with glycerine in-between for the compressive loading plane. Based on the experimental results, failure modes of HSHPC specimens were described. The principal static compressive strengths, strains at the peak stress and stress-strain curves were measured; and the influence of the temperature and stress ratios on them was also analyzed. The experimental results showed that the uniaxial compressive strength of plain HSHPC after exposure to high temperatures does not decrease dramatically with the increase of temperature. The ratio of the biaxial to its uniaxial compressive strength depends on the stress ratios and brittleness-stiffness of HSHPC after exposure to different temperature levels. Comparison of the stress-strain results obtained from the theoretical model and the experimental data indicates good agreement.

  5. Size effect on compressive strength of reactive powder concrete

    Institute of Scientific and Technical Information of China (English)

    AN Ming-zhe; ZHANG Li-jun; YI Quan-xin

    2008-01-01

    In this paper the coefficient and law of the size effect of RPC were studied through experiments and theoretical analysis. The size-effect coefficients for the compressive strength of RPC are deduced through experiments. They indicate that RPC without fiber behaves quite the same as normal or high strength concrete. The size effect on compressive strength is more prominent in RPC containing fiber. Bazant's size effect formula of compressive strength applies to RPC. A formula is given to predict the compressive strength of cubic RPC specimens 100 mm on a side where the fiber dosage ranges from 0-2%.

  6. Shape memory and transformation behavior of high strength 60NiTi in compression

    Science.gov (United States)

    Kaya, I.

    2016-12-01

    This study investigates the transformation behavior of highly Ni-rich 60NiTi alloys after aging at 600 °C for 3 h. After 600 °C-3h aging, R-phase disappeared and alloy transformed in one step. The latent heats of austenite to martensite and martensite to austenite transformations were 13 Jg-1 and 16.4 Jg-1, respectively, for 600 °C-3h aged alloy. The elastic strain energy of 0.75 Jg-1 was obtained in aged alloy. The maximum recoverable transformation strain of 1.7% is obtained under 500 MPa in compression. The superelastic behavior was observed accompanied with a recoverable strain of 1.4%, even high stress level of 1000 MPa is applied.

  7. The Effect of High Temperature on Compression Strength of Geopolymer Paste

    Directory of Open Access Journals (Sweden)

    Bayuaji Ridho

    2017-01-01

    Full Text Available This research has a purpose to confirm the resistance of geopolymer concrete towards high temperature. This high temperature becomes the issues in material structure defense due to the danger of fire. Therefore, this research is done on geopolymer paste, the main binding ingredient from fly ash as local industry waste material. The method that is used in order to achieve the objective is done experimentally in laboratory with the geopolymer testing paste constructed of type C fly ash. Fly ash was obtained from PT. Petrokimia Gresik. The activator alkali sodium hydroxide (NaOH was designed 6, 10, and 14 Molar. The dimension of specimen shape was cylinder 2.5 cm × 5 cm. The maintenance of specimen done in a room temperature (27±3°C until testing period 28 days and proceeded by test item burning process on 200°C and 600°C for 4 hours. The testing of the test item that is done includes the pressure strength test according to SNI-1974-1990. The result of this research shows that the pressure strength of geopolymer paste with NaOH 6, 10, and 14 molar at 200°C temperature has a better pressure strength than room temperature geopolymer paste.

  8. Compressive strength of continuous fiber unidirectional composites

    Science.gov (United States)

    Thompson, Ronald H.

    Dow and Rosen's work in 1965 formed an intellectual framework for compressive strength of unidirectional composites. Compressive strength was explained in terms of micro-buckling, in which filaments are beams on an elastic foundation. They made simplifying assumptions, with a two dimensional idealization and linearized material properties. This study builds on their model, recognizing that the shear mode of instability drives unidirectional compressive strength. As a necessary corollary, the predictive methods developed in this study emphasize correct representation of composite shear stiffness. Non-linear effects related to matrix material properties, fiber misalignment, three dimensional representation, and thermal prestrains are taken into account. Four work streams comprise this study: first, development of a closed form analytical model; second, empirical methods development and model validation; third, creation and validation of a unit cell finite element model; and fourth, a patent application that leverages knowledge gained from the first three work streams. The analytical model characterizes the non-linearity of the matrix both with respect to shear and compressive loading. This improvement on existing analyses clearly shows why fiber modulus affects composite shear instability. Accounting for fiber misalignment in the model and experimental characterization of the fiber misalignment continuum are important contributions of this study. A simple method of compressive strength measurement of a small diameter monofilament glass-resin composite is developed. Sample definition and preparation are original, and necessary technologies are easily assessable to other researchers in this field. This study shows that glass fiber composites have the potential for high compressive strength. This potential is reached with excellent fiber alignment and suitable matrix characteristics, and results are consistent with model predictions. The unit cell three dimensional

  9. Effect of High-Temperature Curing Methods on the Compressive Strength Development of Concrete Containing High Volumes of Ground Granulated Blast-Furnace Slag

    Directory of Open Access Journals (Sweden)

    Wonsuk Jung

    2017-01-01

    Full Text Available This paper investigates the effect of the high-temperature curing methods on the compressive strength of concrete containing high volumes of ground granulated blast-furnace slag (GGBS. GGBS was used to replace Portland cement at a replacement ratio of 60% by binder mass. The high-temperature curing parameters used in this study were the delay period, temperature rise, peak temperature (PT, peak period, and temperature down. Test results demonstrate that the compressive strength of the samples with PTs of 65°C and 75°C was about 88% higher than that of the samples with a PT of 55°C after 1 day. According to this investigation, there might be optimum high-temperature curing conditions for preparing a concrete containing high volumes of GGBS, and incorporating GGBS into precast concrete mixes can be a very effective tool in increasing the applicability of this by-product.

  10. Novel tricalcium silicate/magnesium phosphate composite bone cement having high compressive strength, in vitro bioactivity and cytocompatibility.

    Science.gov (United States)

    Liu, Wenjuan; Zhai, Dong; Huan, Zhiguang; Wu, Chengtie; Chang, Jiang

    2015-07-01

    Although inorganic bone cements such as calcium phosphate cements have been widely applied in orthopaedic and dental fields because of their self-setting ability, development of high-strength bone cement with bioactivity and biodegradability remains a major challenge. Therefore, the purpose of this study is to prepare a tricalcium silicate/magnesium phosphate (C3S/MPC) composite bone cement, which is intended to combine the excellent bioactivity of C3S with remarkable self-setting properties and mechanical strength of MPC. The self-setting and mechanical properties, in vitro induction of apatite formation and degradation behaviour, and cytocompatibility of the composite cements were investigated. Our results showed that the C3S/MPC composite cement with an optimal composition had compressive strength up to 87 MPa, which was significantly higher than C3S (25 MPa) and MPC (64 MPa). The setting time could be adjusted between 3 min and 29 min with the variation of compositions. The hydraulic reaction products of the C3S/MPC composite cement were composed of calcium silicate hydrate (CSH) derived from the hydration of C3S and gel-like amorphous substance. The C3S/MPC composite cements could induce apatite mineralization on its surface in SBF solution and degraded gradually in Tris-HCl solution. Besides, the composite cements showed good cytocompatibility and stimulatory effect on the proliferation of MC3T3-E1 osteoblast cells. Our results indicated that the C3S/MPC composite bone cement might be a new promising high-strength inorganic bioactive material which may hold the potential for bone repair in load-bearing site.

  11. Properties of Compressive Strength and Heating Value of Compressed Semi-Carbonized Sugi thinning

    Science.gov (United States)

    Sawai, Toru; Kajimoto, Takeshi; Akasaka, Motofumi; Kaji, Masuo; Ida, Tamio; Fuchihata, Manabu; Honjyo, Takako; Sano, Hiroshi

    Sugi thinnings with small diameter that are not suitable for lumber can be considered as important domestic energy resources. To utilize Sugi thinnings as alternative fuel of coal cokes, properties of compressive strength and heating value of compressed semi-carbonized wood fuel are investigated. To enhance the heating value, "semi-carbonization", that is the pyrolysis in the temperature range between 200 and 400 degree, is conducted. From the variation of heating value and energy yield of char with pyrolysis temperature, the semi-carbonization pyrolysis is found to be the upgrading technology to convert the woody biomass into the high energy density fuel at high energy yield. To increase the compressive strength, "Cold Isostatic Pressing" method is adopted. The compressive strength of the compressed wood fuel decreases with pyrolysis temperature, while the heating value increases. The drastic decrease in the compressive strength is observed at temperature of 250 degree. The increase in the hydrostatic compression pressure improves the compressive strength for an entire range of semi-carbonization pyrolysis. The alternative fuel with high heating value and high compressive strength can be produced by the semi-carbonization processing at temperature of 280 degree for wood fuel compressed at hydrostatic pressure of 200MPa.

  12. Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions

    Directory of Open Access Journals (Sweden)

    Othuman Mydin M.A.

    2014-01-01

    Full Text Available Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder.

  13. Compressive Strength of Compacted Clay-Sand Mixes

    Directory of Open Access Journals (Sweden)

    Faseel Suleman Khan

    2014-01-01

    Full Text Available The use of sand to improve the strength of natural clays provides a viable alternative for civil infrastructure construction involving earthwork. The main objective of this note was to investigate the compressive strength of compacted clay-sand mixes. A natural clay of high plasticity was mixed with 20% and 40% sand (SP and their compaction and strength properties were determined. Results indicated that the investigated materials exhibited a brittle behaviour on the dry side of optimum and a ductile behaviour on the wet side of optimum. For each material, the compressive strength increased with an increase in density following a power law function. Conversely, the compressive strength increased with decreasing water content of the material following a similar function. Finally, the compressive strength decreased with an increase in sand content because of increased material heterogeneity and loss of sand grains from the sides during shearing.

  14. optimizing compressive strength characteristics of hollow building ...

    African Journals Online (AJOL)

    eobe

    This paper evaluates the compressive strength of sandcrete hollow building blocks when its sand fraction is partially replaced ... defines sandcrete blocks as composite materials made .... industry as well as the economy of Nigeria, if there is no.

  15. Hybrid microscaffold-based 3D bioprinting of multi-cellular constructs with high compressive strength: A new biofabrication strategy

    Science.gov (United States)

    Tan, Yu Jun; Tan, Xipeng; Yeong, Wai Yee; Tor, Shu Beng

    2016-01-01

    A hybrid 3D bioprinting approach using porous microscaffolds and extrusion-based printing method is presented. Bioink constitutes of cell-laden poly(D,L-lactic-co-glycolic acid) (PLGA) porous microspheres with thin encapsulation of agarose-collagen composite hydrogel (AC hydrogel). Highly porous microspheres enable cells to adhere and proliferate before printing. Meanwhile, AC hydrogel allows a smooth delivery of cell-laden microspheres (CLMs), with immediate gelation of construct upon printing on cold build platform. Collagen fibrils were formed in the AC hydrogel during culture at body temperature, improving the cell affinity and spreading compared to pure agarose hydrogel. Cells were proven to proliferate in the bioink and the bioprinted construct. High cell viability up to 14 days was observed. The compressive strength of the bioink is more than 100 times superior to those of pure AC hydrogel. A potential alternative in tissue engineering of tissue replacements and biological models is made possible by combining the advantages of the conventional solid scaffolds with the new 3D bioprinting technology. PMID:27966623

  16. Compressive strength of thick composite panels

    DEFF Research Database (Denmark)

    Branner, Kim; Berring, Peter

    2011-01-01

    The aim of this study is to investigate how much the compressive strength of thick composite panels is reduced due to delaminations and to investigate under which conditions a delamination will grow. Understanding of this is essential in order to move forward the design limits used in the structu......The aim of this study is to investigate how much the compressive strength of thick composite panels is reduced due to delaminations and to investigate under which conditions a delamination will grow. Understanding of this is essential in order to move forward the design limits used...

  17. PREPARATION OF BIOACTIVE NANOSTRUCTURE SCAFFOLD WITH IMPROVED COMPRESSIVE STRENGTH

    Directory of Open Access Journals (Sweden)

    R. EMADI

    2011-03-01

    Full Text Available Highly porous scaffolds with open structure are today the best candidates for bone substitution to ensure bone oxygenation and angiogenesis. In this study, we developed a new route to enhance the compressive strength of porous hydroxyapatite scaffold made of natural bone. Briefly, the spongy bone of an adult bovine was extracted, annealed, and coated by a nanostructure bioactive glass layer to be subsequently sintered at different temperatures. The apatite formation ability on the surfaces of the coated scaffolds was investigated by standard procedures. Our results showed that the scaffold and coating microstructure consisted of the grains smaller than 100 nm. These nanostructures improved the compressive strength and bioactivity of highly porous scaffold. The results showed that with increasing the sintering temperature, the compressive strength of scaffolds increased while their in vitro bioactivity decreased.

  18. models for predicting compressive strength and water absorption of ...

    African Journals Online (AJOL)

    user

    combine laterite and quarry dust in sandcrete blocks or concrete are few. One of ... model for optimization of compressive strength of sand- laterite blocks using ..... compressive strength of Pulverise fuel Ash-Cement concrete''. IOSR Journal of ...

  19. Compressive strength of delaminated aerospace composites.

    Science.gov (United States)

    Butler, Richard; Rhead, Andrew T; Liu, Wenli; Kontis, Nikolaos

    2012-04-28

    An efficient analytical model is described which predicts the value of compressive strain below which buckle-driven propagation of delaminations in aerospace composites will not occur. An extension of this efficient strip model which accounts for propagation transverse to the direction of applied compression is derived. In order to provide validation for the strip model a number of laminates were artificially delaminated producing a range of thin anisotropic sub-laminates made up of 0°, ±45° and 90° plies that displayed varied buckling and delamination propagation phenomena. These laminates were subsequently subject to experimental compression testing and nonlinear finite element analysis (FEA) using cohesive elements. Comparison of strip model results with those from experiments indicates that the model can conservatively predict the strain at which propagation occurs to within 10 per cent of experimental values provided (i) the thin-film assumption made in the modelling methodology holds and (ii) full elastic coupling effects do not play a significant role in the post-buckling of the sub-laminate. With such provision, the model was more accurate and produced fewer non-conservative results than FEA. The accuracy and efficiency of the model make it well suited to application in optimum ply-stacking algorithms to maximize laminate strength.

  20. Modelling the effect of shear strength on isentropic compression experiments

    Science.gov (United States)

    Thomson, Stuart; Howell, Peter; Ockendon, John; Ockendon, Hilary

    2017-01-01

    Isentropic compression experiments (ICE) are a way of obtaining equation of state information for metals undergoing violent plastic deformation. In a typical experiment, millimetre thick metal samples are subjected to pressures on the order of 10 - 102 GPa, while the yield strength of the material can be as low as 10-2 GPa. The analysis of such experiments has so far neglected the effect of shear strength, instead treating the highly plasticised metal as an inviscid compressible fluid. However making this approximation belies the basic elastic nature of a solid object. A more accurate method should strive to incorporate the small but measurable effects of shear strength. Here we present a one-dimensional mathematical model for elastoplasticity at high stress which allows for both compressibility and the shear strength of the material. In the limit of zero yield stress this model reproduces the hydrodynamic models currently used to analyse ICEs. Numerical solutions of the governing equations will then be presented for problems relevant to ICEs in order to investigate the effects of shear strength compared with a model based purely on hydrodynamics.

  1. Non-Uniform Compressive Strength of Debonded Sandwich Panels

    DEFF Research Database (Denmark)

    Nøkkentved, Alexandros; Lundsgaard-Larsen, Christian; Berggreen, Carl Christian

    2005-01-01

    debonds show a considerable strength reduction with increasing debond diameter, with failure mechanisms varying between fast debond propagation and wrinkling-introduced face compression failure for large and small debonds, respectively. Residual strength predictions are based on intact panel testing...

  2. Empirical Formula for the Relationship between Compressive Strength and Test Temperature of Carbon/Polyimide Composites

    OpenAIRE

    濱口, 泰正; Hamaguchi, Yasumasa

    2002-01-01

    T800H/PMR-15 carbon/polyimide composite possesses good specific strength and specific rigidity in the high-temperature region around 300C. This material is an advanced structural composite for use in elevons and other secondary structures of the unmanned space reentry vehicle HOPE-X. The author carried out basic strength evaluation tests on this material. Compressive strength data is especially important for structural design using composite materials. Compressive strength data was therefore ...

  3. 49 CFR 238.405 - Longitudinal static compressive strength.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Longitudinal static compressive strength. 238.405 Section 238.405 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... II Passenger Equipment § 238.405 Longitudinal static compressive strength. (a) To form an...

  4. The uniaxial compressive strength of the Arctic summer sea ice

    Institute of Scientific and Technical Information of China (English)

    HAN Hongwei; LI Zhijun; HUANG Wenfeng; LU Peng; LEI Ruibo

    2015-01-01

    The results on the uniaxial compressive strength of Arctic summer sea ice are presented based on the sam-ples collected during the fifth Chinese National Arctic Research Expedition in 2012 (CHINARE-2012). Exper-imental studies were carried out at different testing temperatures (−3, −6 and −9°C), and vertical samples were loaded at stress rates ranging from 0.001 to 1 MPa/s. The temperature, density, and salinity of the ice were measured to calculate the total porosity of the ice. In order to study the effects of the total porosity and the density on the uniaxial compressive strength, the measured strengths for a narrow range of stress rates from 0.01 to 0.03 MPa/s were analyzed. The results show that the uniaxial compressive strength decreases linearly with increasing total porosity, and when the density was lower than 0.86 g/cm3, the uniaxial com-pressive strength increases in a power-law manner with density. The uniaxial compressive behavior of the Arctic summer sea ice is sensitive to the loading rate, and the peak uniaxial compressive strength is reached in the brittle-ductile transition range. The dependence of the strength on the temperature shows that the calculated average strength in the brittle-ductile transition range, which was considered as the peak uniaxial compressive strength, increases steadily in the temperature range from −3 to −9°C.

  5. Compressive strength of brick masonry made with weak mortars

    DEFF Research Database (Denmark)

    Pedersen, Erik Steen; Hansen, Klavs Feilberg

    2013-01-01

    The use of weak mortar has a number of advantages (e.g. prevention of expansion joints, environmental issues). However, according to EC6, the strength of masonry vanishes when the compressive strength of the mortar approaches zero. In reality the presence of even unhardened mortar kept in place...... (fm≈6 N/mm2) compression tests of masonry with perforated bricks show that the EC6 expression is not always safe for Danish masonry. This is probably because the tensile strength of the bricks also has an effect on the compressive strength of masonry when the mortar is stronger than weak lime mortar...

  6. 欧特克发布基于BIM的概念设计软件--Autodesk Infrastructure Modeler 2012%Investigation of Stability of Axial Compressed Member of High Strength Steel

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    One of the research emphases of application and investigation of high strength steel are laid on stability of axial compressed member. After analyzing stability of high strength steel and limitations of design method for stability of high strength steel analyzed, combined with the function of stability analysis of large finite element analysis software ANSYS and model test, stability for axial compressed members of high strength steel are researched, and formulae which parameter includes yield strength of material and slenderness ratio of member is put forward for calculation stability coefficient of axial compressed member of high strength steel. Some important conclusions are arrived at. The research is significant for application and investigation of high strength steel in future.%欧特克有限公司宣布,欧特克建筑信息模型(BIM)基础设施产品组合新增面向概念设计的Autodesk Infrastructure Modeler 2012软件。基于BIM的基础设施产品组合主要用于规划、设计、建设和管理更具可持续性的基础设施。新产品将与2012版欧特克基础设施设计套件配套,可帮助业内专业人士提高效率,并消除工作过程中产生的浪费。

  7. Application of size effect to compressive strength of concrete members

    Indian Academy of Sciences (India)

    Jin-Keun Kim; Seong-Tae Yi

    2002-08-01

    It is important to consider the effect of size when estimating the ultimate strength of a concrete member under various loading conditions. Well known as the size effect, the strength of a member tends to decrease when its size increases. Therefore, in view of recent increased interest in the size effect of concrete this research focuses on the size effect of two main classes of compressive strength of concrete: pure axial compressive strength and flexural compressive strength. First, fracture mechanics type size effect on the compressive strength of cylindrical concrete specimens was studied, with the diameter, and the height/diameter ratio considered as the main parameters. Theoretical and statistical analyses were conducted, and a size effect equation was proposed to predict the compressive strength specimens. The proposed equation showed good agreement with the existing test results for concrete cylinders. Second, the size, length, and depth variations of a flexural compressive member have been studied experimentally. A series of -shaped specimens subjected to axial compressive load and bending moment were tested. The shape of specimens and the test procedures used were similar to those by Hognestad and others. The test results are curve-fitted using Levenberg-Marquardt’s least squares method (LSM) to obtain parameters for the modified size effect law (MSEL) by Kim and co workers. The results of the analysis show that the effect of specimen size, length, and depth on ultimate strength is significant. Finally, more general parameters for MSEL are suggested.

  8. Effect of Metakaolin on Compressive Strength of Concrete

    Directory of Open Access Journals (Sweden)

    Satyendra Dubey

    2015-06-01

    Full Text Available Metakaolin is a cementitious materials used as an admixture to produce high strength concrete and is used for maintaining the consistency of concrete. In the case where insufficient or poor curing concrete structure like the underground structure which undergo serve loss of compressive strength, use of metakaolin proves to be very useful to modify the properties of concrete. This paper deals with the properties of concrete with varying percentage replacement of metakaolin in M-25 greade of concrete. The mix M1,M2,M3 and M4 were obtained by replacing 0,5,10 and 15 percent mass of cement by Metakaolin. The test results indicated that admixture metakaolin when used at optimum quantity tend to increase the strength of the concrete mix when compared with conventional concrete.

  9. Compressive Strength Development and Microstrueture of Cement.asphalt Mortar

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; YAN Peiyu; KONG Xiangming; YANG Jinbo

    2011-01-01

    The compressive strength developing process and the microstructure of cement-asphalt mortar (CA mortar) were investigated.The fluidity of CA mortar has a great influence on its strength.The optimum value of spread diameter of slump flow test is in the range of 300 to 400 mm.The compressive strength of CA mortar keeps a relatively high growth rate in 56 days and grows slowly afterwards.The residual water of hydration in CA mortar freezes under minus environmental temperature which can lead to a significant reduction of the strength of CA mortar.Increasing A/C retards asphalt emulsion splitting and thus prolongs the setting process of CA mortar.The hydration products of cement form the major structural framework of hardened CA mortar and asphalt is a weak phase in the framework but improves the viscoelastic behavior of CA mortar.Therefore,asphalt emulsion should be used as much as possible on the condition that essential performance criterions of CA mortar are satisfied.

  10. Influence of fly ash and desert Sand content on the compressive strength of high strength concrete%掺粉煤灰、沙漠砂高强混凝土抗压强度研究

    Institute of Scientific and Technical Information of China (English)

    陈云龙; 马菊荣; 刘海峰; 宋建夏

    2014-01-01

    The orthogonal experiment was designed to analyze the influence of water-binder ratio,fly ash content,sand ratio and desert sand replacement ratio on the compressive strength of high strength concrete at the different age.The optimum mix ratio of desert sand high-strength concrete was also given out.Experimental result showed that it is practical to use the desert sand from Mu Us desert sand to mix high strength concrete,the optimum mix ratio of which was that water-binder ratio,fly ash dosage,sand ratio and desert sand replace-ment ratio were 0.24,10%,30% and 30%,respectively.%通过正交试验,分析了水胶比、粉煤灰掺量、砂率、沙漠砂取代率对不同龄期高强混凝土抗压强度影响,并给出了配制高强混凝土的最优配合比。研究结果表明:用沙漠砂替代中砂配制高强混凝土是可行的;综合考虑各阶段的抗压强度,高强混凝土的最优配合比为水胶比0.24、粉煤灰掺量10%、砂率30%、沙漠砂取代率30%。

  11. Prediction of concrete compressive strength due to long term sulfate attack using neural network

    Directory of Open Access Journals (Sweden)

    Ahmed M. Diab

    2014-09-01

    Full Text Available This work was divided into two phases. Phase one included the validation of neural network to predict mortar and concrete properties due to sulfate attack. These properties were expansion, weight loss, and compressive strength loss. Assessment of concrete compressive strength up to 200 years due to sulfate attack was considered in phase two. The neural network model showed high validity on predicting compressive strength, expansion and weight loss due to sulfate attack. Design charts were constructed to predict concrete compressive strength loss. The inputs of these charts were cement content, water cement ratio, C3A content, and sulfate concentration. These charts can be used easily to predict the compressive strength loss after any certain age and sulfate concentration for different concrete compositions.

  12. Effect of Banana Fibers on the Compressive and Flexural Strength of Compressed Earth Blocks

    Directory of Open Access Journals (Sweden)

    Marwan Mostafa

    2015-03-01

    Full Text Available Sustainable development of the built environment in developing countries is a major challenge in the 21st century. The use of local materials in construction of buildings is one of the potential ways to support sustainable development in both urban and rural areas. Building with Compressed Earthen Blocks (CEBs is becoming more popular due to their low cost and relative abundance of materials. The proposed Green-Compressed Earth Block (GCEB consists of ordinary CEB ingredients plus Banana fibers, which will be the focus of this study. Banana fibers are widely available worldwide as agricultural waste from Banana cultivation. Banana fibers are environmentally friendly and present important attributes, such as low density, light weight, low cost, high tensile strength, as well as being water and fire resistant. This kind of waste has a greater chance of being utilized for different application in construction and building materials. This focused on the use of banana fiber and its effect on the compressive and flexural strength in CEB. The deflection at the mid-span of the blocks studied was calculated using the Linear Variable Differential Transformer (LVDT. The results of this study will highlight general trends in the strength properties of different soil mixes for CEBs. These efforts are necessary to ensure that GCEB technology becomes more widely accepted in the world of building materials and is considered a reliable option for providing low-cost housing.

  13. Filler effect of fine particle sand on the compressive strength of mortar

    Science.gov (United States)

    Jaturapitakkul, Chai; Tangpagasit, Jatuphon; Songmue, Sawang; Kiattikomol, Kraiwood

    2011-04-01

    The river sand, which is a non-pozzolanic material, was ground into 3 different particle sizes. Portland cement type I was replaced by the ground river sands at 10wt%-40wt% of binder to cast mortar. Compressive strengths of mortar were investigated and the filler effect of different fine particles of sand on the compressive strength of mortar was evaluated. The results show that the compressive strength of mortar contributed from the filler effect of smaller particles is higher than that of the coarser ones. The difference in compressive strength of mortar tends to be greater as the difference in ground river sand fineness increases. The results also suggest that ASTM C618 specification is not practically suitable for specifying pozzolan in concrete since the strength activity index of mortar containing ground river sand (high crystalline phase) with 33.8wt% of particles retained on a 45-μm sieve can pass the strength requirement.

  14. effect of crude oil contamination on the compressive strength of ...

    African Journals Online (AJOL)

    hp

    This revealed clearly that crude oil is a compressive strength inhibitor in the production of concrete. ... the near shore community. ... the resulting emulsified water, affect aquatic life [3]. 2. ... impacts. Large areas of the mangrove ecosystem have.

  15. damaging effects of dieldrex-20 on the compressive strength of ...

    African Journals Online (AJOL)

    Dr Obe

    termite resistant concrete, as dosage in excess of this could adversely affect the compressive strength of concrete. ... There is a great need to reduce and limit damages ... aqueous solution (one litre or dieldrex-20 to 39 .... tropical climate, proc.

  16. Compressive strength of brick masonry made with weak mortars

    DEFF Research Database (Denmark)

    Pedersen, Erik Steen; Hansen, Klavs Feilberg

    2013-01-01

    The use of weak mortar has a number of advantages (e.g. prevention of expansion joints, environmental issues). However, according to EC6, the strength of masonry vanishes when the compressive strength of the mortar approaches zero. In reality the presence of even unhardened mortar kept in place...... in the joint will ensure a certain level of load-carrying capacity. This is due to the interaction between compression in the weak mortar and tension in the adjacent bricks. This paper proposes an expression for the compressive strength of masonry made with weak lime mortars (fm... of masonry depends only on the strength of the bricks. A compression failure in masonry made with weak mortars occurs as a tension failure in the bricks, as they seek to prevent the mortar from being pressed out of the joints. The expression is derived by assuming hydrostatic pressure in the mortar joints...

  17. Compressive strength and rheology of environmentally-friendly binders

    Directory of Open Access Journals (Sweden)

    Juan Manuel Lizarazo Marriaga

    2010-07-01

    Full Text Available Ordinary Portland cement production accounts for 9% of worldwide greenhouse gas emissions. This paper summarises the results of research aimed at developing environmentally-friendly binders which can be used as an alternative in civil construction, aimed at generating alternatives and sustainable materials. Mixes of the combination of granulated ground blast furnace slag, basic oxygen slag, cement kiln dust and plasterboard gypsum were used for optimising the binders, according to their compressive strength, to obtain 5 concrete mixtures made partially or completely with industrial waste. The results showed that the compressive strength of mixtures of Portland cement and industrial waste were suitable for different civil construction applications and, although mixtures formed entirely from industrial waste had a significant decrease in their compressive strength, the results sho- wed great potential for specific industrial applications. In addition to compressive strength, the rheological properties of these mixtures were determined for defining flow and workability characteristics.

  18. The Compressive Strength of Carbon Fibre Reinforced Plastics.

    Science.gov (United States)

    1982-08-01

    and resin properties . Therefore, throughout this Report the term compressive failure will imply a microbuckling failure mode. A microbuckling failure...Compressive strength of fibre reinforced composite materials. ASTM STP 580, pp 364-377 (1975) 16 D.B.S. Berry Handbook of resin properties . Part A - cast

  19. Evaluation of adhesive and compressive strength of glass ionomer cements.

    Science.gov (United States)

    Ramashanker; Singh, Raghuwar D; Chand, Pooran; Jurel, Sunit Km; Tripathi, Shuchi

    2011-12-01

    The aim of the study was to assess, compare and evaluate the adhesive strength and compressive strength of different brands of glass ionomer cements to a ceramometal alloy. (A) Glass ionomer cements: GC Fuji II (GC Corporation, Tokyo), Chem Flex (Dentsply DeTrey, Germany), Glass ionomer FX (Shofu-11, Japan), MR dental (MR dental suppliers Pvt Ltd, England). (B) Ceramometal alloy (Ni-Cr: Wiron 99; Bego, Bremen, Germany). (C) Cold cure acrylic resin. (E) Temperature cum humidity control chamber. (F) Instron Universal Testing Machine. Four different types of Glass ionomer cements were used in the study. From each type of the Glass ionomer cements, 15 specimens for each were made to evaluate the compressive strength and adhesive strength, respectively. The 15 specimens were further divided into three subgroups of five specimens. For compressive strength, specimens were tested at 2, 4 and 12 h by using Instron Universal Testing Machine. To evaluate the adhesive strength, specimens were surface treated with diamond bur, silicone carbide bur and sandblasting and tested under Instron Universal Testing Machine. It was concluded from the study that the compressive strength as well as the adhesive bond strength of MR dental glass ionomer cement with a ceramometal alloy was found to be maximum compare to other glass ionomer cements. Sandblasting surface treatment of ceramometal alloy was found to be comparatively more effective for adhesive bond strength between alloy and glass ionomer cement.

  20. Compressive Strength of Longitudinally Stiffened GRP Panels

    DEFF Research Database (Denmark)

    Böhme, J.; Noury, P.; Riber, Hans Jørgen

    1996-01-01

    A structural analysis of a cross stiffened orthotropic GRP panel subjected to uniaxial compressive loads is carried out. Analytical solutions to the buckling of such structures are proposed and validated by a finite element analysis. Both analytical and finite element approaches confirm an identi...

  1. Compressive Strength of Longitudinally Stiffened GRP Panels

    DEFF Research Database (Denmark)

    Böhme, J.; Noury, P.; Riber, Hans Jørgen

    1996-01-01

    A structural analysis of a cross stiffened orthotropic GRP panel subjected to uniaxial compressive loads is carried out. Analytical solutions to the buckling of such structures are proposed and validated by a finite element analysis. Both analytical and finite element approaches confirm an identi...

  2. Prediction of Splitting Tensile Strength from Cylinder Compressive Strength of Concrete by Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Kezhen Yan

    2013-01-01

    Full Text Available Compressive strength and splitting tensile strength are both important parameters that are utilized for characterization concrete mechanical properties. This paper aims to show a possible applicability of support vector machine (SVM to predict the splitting tensile strength of concrete from compressive strength of concrete, a SVM model was built, trained, and tested using the available experimental data gathered from the literature. All of the results predicted by the SVM model are compared with results obtained from experimental data, and we found that the predicted splitting tensile strength of concrete is in good agreement with the experimental data. The splitting tensile strength results predicted by SVM are also compared to those obtained by using empirical results of the building codes and various models. These comparisons show that SVM has strong potential as a feasible tool for predicting splitting tensile strength from compressive strength.

  3. Static strength of gold compressed up to 127 GPa

    Institute of Scientific and Technical Information of China (English)

    Jing Qiu-Min; Wu Qiang; Liu Lei; Bi Yan; Zhang Yi; Liu Sheng-Gang; Xu Ji-An

    2012-01-01

    Gold powder is compressed non-hydrostatically up to 127 GPa in a diamond anvil cell (DAC),and its angle dispersive X-ray diffraction patterns are recorded.The compressive strength of gold is investigated in a framework of the lattice strain theory by the line shift analysis.The result shows that the compressive strength of gold increases continuously with the pressure up to 106 GPa and reaches 2.8 GPa at the highest experimental pressure (127 GPa) achieved in our study.This result is in good agreement with our previous experimental result in a relevant pressure range.The compressive strength of gold may be the major source of the error in the equation-of-state measurement in various pressure environments.

  4. Prediction of 28-day Compressive Strength of Concrete from Early Strength and Accelerated Curing Parameters

    OpenAIRE

    T.R. Neelakantan; S. Ramasundaram; Shanmugavel, R.; R. Vinoth

    2013-01-01

    Predicting 28-day compressive strength of concrete is an important research task for many years. In this study, concrete specimens were cured in two phases, initially at room temperature for a maximum of 30 h and later at a higher temperature for accelerated curing for a maximum of 3 h. Using the early strength obtained after the two-phase curing and the curing parameters, regression equations were developed to predict the 28-day compressive strength. For the accelerated curing (higher temper...

  5. Compressive strength and hydrolytic stability of fly ash based geopolymers

    Directory of Open Access Journals (Sweden)

    Nikolić Irena

    2013-01-01

    Full Text Available The process of geopolymerization involves the reaction of solid aluminosilicate materials with highly alkaline silicate solution yielding an aluminosilicate inorganic polymer named geopolymer, which may be successfully applied in civil engineering as a replacement for cement. In this paper we have investigated the influence of synthesis parameters: solid to liquid ratio, NaOH concentration and the ratio of Na2SiO3/NaOH, on the mechanical properties and hydrolytic stability of fly ash based geopolymers in distilled water, sea water and simulated acid rain. The highest value of compressive strength was obtained using 10 mol dm-3 NaOH and at the Na2SiO3/NaOH ratio of 1.5. Moreover, the results have shown that mechanical properties of fly ash based geopolymers are in correlation with their hydrolytic stability. Factors that increase the compressive strength also increase the hydrolytic stability of fly ash based geopolymers. The best hydrolytic stability of fly ash based geopolymers was shown in sea water while the lowest stability was recorded in simulated acid rain. [Projekat Ministarstva nauke Republike Srbije, br. 172054 i Nanotechnology and Functional Materials Center, funded by the European FP7 project No. 245916

  6. Reliability of using nondestructive tests to estimate compressive strength of building stones and bricks

    Directory of Open Access Journals (Sweden)

    Ali Abd Elhakam Aliabdo

    2012-09-01

    Full Text Available This study aims to investigate the relationships between Schmidt hardness rebound number (RN and ultrasonic pulse velocity (UPV versus compressive strength (fc of stones and bricks. Four types of rocks (marble, pink lime stone, white lime stone and basalt and two types of burned bricks and lime-sand bricks were studied. Linear and non-linear models were proposed. High correlations were found between RN and UPV versus compressive strength. Validation of proposed models was assessed using other specimens for each material. Linear models for each material showed good correlations than non-linear models. General model between RN and compressive strength of tested stones and bricks showed a high correlation with regression coefficient R2 value of 0.94. Estimation of compressive strength for the studied stones and bricks using their rebound number and ultrasonic pulse velocity in a combined method was generally more reliable than using rebound number or ultrasonic pulse velocity only.

  7. STRENGTH OF NANOMODIFIED HIGH-STRENGTH LIGHTWEIGHT CONCRETES

    Directory of Open Access Journals (Sweden)

    NOZEMTСEV Alexandr Sergeevich

    2013-02-01

    Full Text Available The paper presents the results of research aimed at development of nanomodified high-strength lightweight concrete for construction. The developed concretes are of low average density and high ultimate compressive strength. It is shown that to produce this type of concrete one need to use hollow glass and aluminosilicate microspheres. To increase the durability of adhesion between cement stone and fine filler the authors offer to use complex nanodimensinal modifier based on iron hydroxide sol and silica sol as a surface nanomodifier for hollow microspheres. It is hypothesized that the proposed modifier has complex effect on the activity of the cement hydration and, at the same time increases bond strength between filler and cement-mineral matrix. The compositions for energy-efficient nanomodified high-strength lightweight concrete which density is 1300…1500 kg/m³ and compressive strength is 40…65 MPa have been developed. The approaches to the design of high-strength lightweight concrete with density of less than 2000 kg/m³ are formulated. It is noted that the proposed concretes possess dense homogeneous structure and moderate mobility. Thus, they allow processing by vibration during production. The economic and practical implications for realization of high-strength lightweight concrete in industrial production have been justified.

  8. Calcite-forming bacteria for compressive strength improvement in mortar.

    Science.gov (United States)

    Park, Sung-Jin; Park, Yu-Mi; Chun, Woo-Young; Kim, Wha-Jung; Ghim, Sa-Youl

    2010-04-01

    Microbiological calcium carbonate precipitation (MCP) has been investigated for its ability to improve the compressive strength of concrete mortar. However, very few studies have been conducted on the use of calcite-forming bacteria (CFB) to improve compressive strength. In this study, we discovered new bacterial genera that are capable of improving the compressive strength of concrete mortar. We isolated 4 CFB from 7 environmental concrete structures. Using sequence analysis of the 16S rRNA genes, the CFB could be partially identified as Sporosarcina soli KNUC401, Bacillus massiliensis KNUC402, Arthrobacter crystallopoietes KNUC403, and Lysinibacillus fusiformis KNUC404. Crystal aggregates were apparent in the bacterial colonies grown on an agar medium. Stereomicroscopy, scanning electron microscopy, and x-ray diffraction analyses illustrated both the crystal growth and the crystalline structure of the CaCO3 crystals. We used the isolates to improve the compressive strength of concrete mortar cubes and found that KNUC403 offered the best improvement in compressive strength.

  9. Prediction of Concrete Compressive Strength by Evolutionary Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Mehdi Nikoo

    2015-01-01

    Full Text Available Compressive strength of concrete has been predicted using evolutionary artificial neural networks (EANNs as a combination of artificial neural network (ANN and evolutionary search procedures, such as genetic algorithms (GA. In this paper for purpose of constructing models samples of cylindrical concrete parts with different characteristics have been used with 173 experimental data patterns. Water-cement ratio, maximum sand size, amount of gravel, cement, 3/4 sand, 3/8 sand, and coefficient of soft sand parameters were considered as inputs; and using the ANN models, the compressive strength of concrete is calculated. Moreover, using GA, the number of layers and nodes and weights are optimized in ANN models. In order to evaluate the accuracy of the model, the optimized ANN model is compared with the multiple linear regression (MLR model. The results of simulation verify that the recommended ANN model enjoys more flexibility, capability, and accuracy in predicting the compressive strength of concrete.

  10. The impact of water content and ionic diffusion on the uniaxial compressive strength of shale

    OpenAIRE

    Talal AL-Bazali

    2013-01-01

    Experimental data showed that water content has a profound influence on the uniaxial compressive strength of shale. Testing has shown a great decrease in the uniaxial compressive strength as the water content increases. Regression analysis was used in this work to develop a general equation for predicting uniaxial compressive strength of shale from the available information on its water content and dry uniaxial compressive strength. The impact of ionic diffusion on the compressive strength...

  11. Shear Reinforcement Requirements for High-Strength Concrete Bridge Girders

    OpenAIRE

    Ramirez, J. A.; Aguilar, Gerardo

    2005-01-01

    A research program was conducted on the shear strength of high-strength concrete members. The objective was to evaluate the shear behavior and strength of concrete bridge members with compressive strengths in the range of 10 000 to 15 000 psi. The goal was to determine if the current minimum amount of shear reinforcement together with maximum spacing limits in the 2004 AASHTO LRFD Specifications, and the upper limit on the nominal shear strength were applicable to concrete compressive strengt...

  12. Effect of Pelletized Coconut Fibre on the Compressive Strength of Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Mohd Jaini Zainorizuan

    2016-01-01

    Full Text Available Foamed concrete is a controlled low density ranging from 400kg/m3 to 1800kg/m3, and hence suitable for the construction of buildings and infrastructures. The uniqueness of foamed concrete is does not use aggregates in order to retain low density. Foamed concrete contains only cement, sand, water and foam agent. Therefore, the consumption of cement is higher in producing a good quality and strength of foamed concrete. Without the present of aggregates, the compressive strength of foamed concrete can only achieve as high as 15MPa. Therefore, this study aims to introduce the pelletized coconut fibre aggregate to reduce the consumption of cement but able to enhance the compressive strength. In the experimental study, forty-five (45 cube samples of foamed concrete with density 1600kg/m3 were prepared with different volume fractions of pelletized coconut fibre aggregate. All cube samples were tested using the compression test to obtain compressive strength. The results showed that the compressive strength of foamed concrete containing 5%, 10%, 15% and 20% of pelletized coconut fibre aggregate are 9.6MPa, 11.4MPa, 14.6MPa and 13.4MPa respectively. It is in fact higher than the controlled foamed concrete that only achieves 9MPa. It is found that the pelletized coconut fibre aggregate indicates a good potential to enhance the compressive strength of foamed concrete.

  13. High strength alloys

    Science.gov (United States)

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  14. High strength alloys

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  15. Evaluation of Concrete Compressive Strength by incorporating Used Foundry Sand

    Directory of Open Access Journals (Sweden)

    Khuram Rashid

    2016-07-01

    Full Text Available The main objective of this study was to evaluate the compressive strength of concrete by utilizing three types of used foundry sand; with bentonite clay, with sodium silicate & with phenolic resin as partial replacement of fine aggregates. To accomplish the research an experimental program was conducted in which ten concrete mixtures were casted, by keeping all other parameters for concrete proportioning as constant and only change made was in the amount of fine aggregates. Ten, Twenty and Thirty percent replacement level of river sand by used foundry sands was maintained in this study. All fine aggregates were selected after achieving desired physical and chemical tests. Work ability, compressive strength and modulus of elasticity were measured and compared with the conventional concrete termed as control mixture. It was observed that work ability increased with replacement levels. The cubes were crushed at 7, 28 and 63 days of standard moist curing. The compressive strength of all concrete specimens increased with increase in curing age. With exception to foundry sand with phenolic resin, compressive strength of concrete mixtures was decreased with increase in replacement level at all ages. Similar trends were observed in modulus of elasticity of concrete.

  16. comparative analysis of the compressive strength of hollow ...

    African Journals Online (AJOL)

    user

    2016-04-02

    Apr 2, 2016 ... 1,2,3 DEPARTMENT OF CIVIL ENGINEERING, UNIVERSITY OF NIGERIA, NSUKKA, ENUGU STATE, NIGERIA ... This research performed a comparative analysis of the compressive strength ... Print ISSN: 0331-8443, Electronic ISSN: 2467-8821 ..... Journal. of Engineering Project and Production.

  17. comparative analysis of the compressive strength of concrete with ...

    African Journals Online (AJOL)

    2013-03-01

    Mar 1, 2013 ... in compression than in tension, for structures required to carry only ... properties determine the quality of concrete [1]. Concrete is one of the .... strength concrete made with crushed brick as coarse aggregate and ... aggregates that have been produced from demolition and construction waste. According to ...

  18. effect of curing methods on the compressive strength of concrete

    African Journals Online (AJOL)

    ods on the compressive strength as well as the density of concrete. A total of 72 cubes of ... Review of Related Literatures. In concrete ... and plastic sheet is essential in order to pro- .... This is due to improved pore structure and lower porosity.

  19. Effect Of Bulk Density Variation On The Compression Strength Of ...

    African Journals Online (AJOL)

    Effect Of Bulk Density Variation On The Compression Strength Of ... or their mixture (1 wt % each). was added to first, second and third portion respectively. ... namely, the number of sand-grain-to-sand-grain contact and the number of pores in ...

  20. Effect of thickness of bonded composite resin on compressive strength

    NARCIS (Netherlands)

    Hamburger, J.T.; Opdam, N.J.; Bronkhorst, E.M.; Roeters, J.; Huysmans, M.C.

    2014-01-01

    OBJECTIVE: The aim of this study was to investigate the compressive strength of composites with different physical properties bonded as a restoration to dentin in layers of varying thicknesses. METHODS: Four types of direct composite materials: a midway-filled (Tetric EvoCeram); a compact-filled (Cl

  1. Cement paste compressive strength estimation using nondestructive microwave reflectometry

    Science.gov (United States)

    Zoughi, Reza; Gray, S.; Nowak, Paul S.

    1994-09-01

    Microwave reflection properties of four cement paste samples with various water-cement (w/c) ratios were measured daily for 28 days using microwave frequencies of 5, 9, and 13 GHz. The dielectric properties of these samples, and hence their reflection coefficients, were measured daily and shown to decrease as a function of increasing w/c ratio. This is as a direct result of curing (no chemical interaction or hydration). The presence of curing as indicated by this result indicates that microwaves could be used to monitor the amount of curing in a concrete member. The variation in the reflection coefficient of these samples as a function of w/c ratio followed a trend similar to the variation of compressive strength as a function of w/c ratio. Subsequently, a correlation between the measured compressive strength and reflection coefficient of these blocks was obtained. The early results indicated that lower frequencies are more sensitive to compressive strength variations. However, further investigations showed that there may be a frequency around 5 GHz which is the optimum measurement frequency. This result can be used to directly and nondestructively estimate the compressive strength of a cement paste and mortar blocks.

  2. Forecast Jointed Rock Mass Compressive Strength Using a Numerical Model

    Directory of Open Access Journals (Sweden)

    Protosenya Anatoliy

    2016-01-01

    Full Text Available The method of forecasting the strength of the jointed rock mass by numerical modeling of finite element method in ABAQUS was described. The paper presents advantages of this method to solve the problem of determining the mechanical characteristics of jointed rock mass and the basic steps of creating a numerical geomechanical model of jointed rock mass and numerical experiment. Numerical simulation was carried out with jointed rock mass in order to obtain the ratio of strain and stress while loading the numerical model, determining parameters of quantitative assessment of the impact of the discontinuities orientation on the value of the compressive strength, compressive strength anisotropy. The results of the numerical experiment are compared with the data of experimental studies investigations. Innovative materials and structures are analyzed in this paper. The results that were obtained by calculation show qualitative agreement with the results of laboratory experiments of jointed rock mass.

  3. Predicting The Compression Strength Of Impact-Damaged Sandwich Panels

    Science.gov (United States)

    Ratcliffe, James; Jackson, Wade; Schaff, Jeffery

    1990-01-01

    The objective of this work was to develop a technique for predicting the residual compression strength of sandwich panels containing impact damage in one facesheet. The technique was tailored to predict the strength of specimens that exhibit a failure mode involving the formation of kink bands at locations of peak strain in the region of impact damage. Under continued compression loading, the kink bands propagate in a stable manner perpendicular to the applied load. When a critical kink-band length is reached, growth becomes unstable corresponding to panel failure. The analysis follows in two sections. The first section calculates the far-field stress required for stable kink-band growth and the second calculates that required for unstable growth. The residual strength prediction is made when the stress for stable growth becomes equal to that for unstable kink-band growth. Initial comparisons between analysis and experiment show good agreement.

  4. Compressive Strength of Concrete Containing Palm Kernel Shell Ash

    Directory of Open Access Journals (Sweden)

    FADELE Oluwadamilola A

    2016-12-01

    Full Text Available This study examined the influence of varying palm kernel shell ash content, as supplementary cementitious material (SCM at specified water/cement ratios and curing ages on the compressive strength of concrete cubes samples. Palm kernel shell ash was used as a partial replacement for ordinary Portland cement (OPC up to 30% at 5% intervals using mix ratio 1:2:4. River sand with particles passing 4.75mmBS sieve and crushed aggregate of 20mm maximum size were used while the palm kernel shell ash used was ofparticles passing through 212μm BS sieve. The compressive strength of the test cubes (100mm were tested at 5 different curing ages of 3, 7, 14, 28 and 56 days. The result showed that test cube containing Palm kernel shell ash gained strength over a longer curing period compared with ordinary Portlandcement concrete samples and the strength varies with percentagePKSAcontent in the cube samples. The results showed that at 28 days test cubes containing 5%, 10%, 15%, 20%, 25% and 30% PKSA content achieved compressive strength of 26.1 MPa, 22.53MPa, 19.43 MPa, 20.43 MPa, 16.97 MPa and 16.5MPa compared to 29MPa of Ordinary Portland cement concrete cubes. It was concluded that for structural concrete works requiring a characteristic strength of 25Mpa,5% palm kernel shell ash can effectively replace ordinary Portland cement while up to 15% PKSA content can be used for concrete works requiring 20Mpa strength at 28 days

  5. Compression garment promotes muscular strength recovery after resistance exercise.

    Science.gov (United States)

    Goto, Kazushige; Morishima, Takuma

    2014-12-01

    This study aimed to investigate the effects of wearing a compression garment (CG) for 24 h on changes in muscular strength and blood parameters over time after resistance exercise. Nine trained men conducted resistance exercises (10 repetitions of 3-5 sets at 70% of one-repetition maximum (1RM) for nine exercises) in two trials, wearing either a CG or a normal garment (CON) for 24 h after exercise. Recovery of muscular strength, blood parameters, muscle soreness, and upper arm and thigh circumference were compared between the trials. Both trials showed decreases in maximal strength after the exercise (P creatine kinase, interleukin 6, and interleukin 1 receptor antagonist concentrations for 24 h after exercise were similar in both trials. Wearing a CG after resistance exercise facilitates the recovery of muscular strength. Recovery for upper body muscles significantly improved within 3-8 h after exercise. However, facilitation of recovery of lower limb muscles by wearing the CG took a longer time.

  6. Optimization of compressive strength of zirconia based dental composites

    Indian Academy of Sciences (India)

    U V Hambire; V K Tripathi

    2014-10-01

    Dental composites are tooth-coloured restorative material used by dentists for various applications. Restoration of a lost tooth structure requires a material having mechanical as well as aesthetic properties similar to that of tooth. This poses challenges to engineers and the dentist alike. Dental composites consist of a matrix and a dispersed phase called filler, which are mainly responsible for its mechanical properties. Most commonly used matrix is bisphenol glycidyl methacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGMA). Silica and glass are conventional fillers used in the past. Recently, zirconia is being used due to its improved mechanical properties. A study was conducted to evaluate the contribution of zirconia to the mechanical properties in general and compressive strength in particular. We have attempted to make an experimental dental composite with a conglomerate of nanofillers, namely, zirconia, glass and silica, and optimize this filler volume percentage and obtain an optimum compressive strength for the experimental dental composite.

  7. Residual Compressive Strength of Laterized Concrete Subjected to Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Robert M. Brooks

    2010-05-01

    Full Text Available This research presents the results of an experimental program to investigate the strength performance of laterized concrete (LATCON when subjected to elevated temperatures of 200, 400 and 600ºC. Six concrete mixes incorporating 0, 10, 20, 30, 40 and 50% Laterite as a replacement by weight of sand was prepared. After heat pretreatment specimens were cooled using either rapid cooling (water-cooling or natural cooling (air-cooling. An analysis of variance test shows that exposure temperature, cooling regime, and their interaction have a significant influence on the compressive strength of the samples. When subjected to the investigated temperatures specimens experienced strength losses that increased with temperature. This study further reveals that air-cooled concrete specimens maintained higher residual strength values than water-cooled specimens. A comparison of the residual compressive strength data obtained in this study with code provisions in Eurocode and CEB design curve shows that these codes could be applied to LATCON subjected to temperature below 400ºC.

  8. Estimation of concrete compressive strength using artificial neural network

    OpenAIRE

    Kostić, Srđan; Vasović, Dejan

    2015-01-01

    In present paper, concrete compressive strength is evaluated using back propagation feed-forward artificial neural network. Training of neural network is performed using Levenberg-Marquardt learning algorithm for four architectures of artificial neural networks, one, three, eight and twelve nodes in a hidden layer in order to avoid the occurrence of overfitting. Training, validation and testing of neural network is conducted for 75 concrete samples with distinct w/c ratio and amount of superp...

  9. Compressive Strength of a Longitudinally Stiffened FRP Panel

    DEFF Research Database (Denmark)

    Riber, Hans Jørgen; Jensen, Jørgen Juncher; Pedersen, Preben Terndrup

    1997-01-01

    A structural analysis of a cross stiffened orthotropic FRP panel subjected to uni-axial compressive load is crarried out. Analytical Calculations of the strength of the panel are presented and compared to finite element analysis performed by different authors. Both analytica and finite element ap...... approaches confirm an identical failrue scenario. In the present case, the load carrying capacity of the stiffened panel is limited by the plate stiffener debonding stress....

  10. Tow collapse model for compression strength of textile composites

    Energy Technology Data Exchange (ETDEWEB)

    Emehel, T.C.; Shivakumar, K.N. [North Carolina A and T State Univ., Greensboro, NC (United States)

    1995-12-31

    The unidirectional composite compression strength model based on microbuckling of fibers embedded in a rigid-plastic matrix was extended to multiaxial laminates and textile composites. The resulting expression is a function of matrix yield strength under the fiber constraint, fiber misalignment angle, fiber volume fraction, and the area fractions of various sets of inclined tows. The analysis was verified by experimentation. Compression tests were conducted on laminated, three-dimensional triaxially braided and orthogonally woven composites using the IITRI test specimen. The laminate specimens were made up of AS4/3501-6 graphite/epoxy composite with (0){sub 24}, (0/30/0/{minus}30){sub 3S}, and ((0/90)6/0){sub S} stacking sequence. Textile composites were made of BASF G30-500 graphite fiber tows (tow size is 6K) and Dow Chemicals Tactix 123 matrix. Fiber preform architecture of braided and woven composites before resin consolidation was 0/{+-}17 and 0/90, respectively and after consolidation it was about (7/{+-}20) and (5/90/90), respectively. The analysis agreed reasonably well with the test data for all cases considered. The axial fiber/tow misalignment angle for laminated, braided, and woven composites were about 4, 7, and 5 degrees, respectively. The compression strength was found to be strongly dependent on the percentage of axial tows and its misalignment angle. A small variation in the off-axis fiber/tow orientation had marginal effect on the compression strength. Hence, the off axis tow misalignment angle can be assumed to be same as the initial laminate or the two orientation angle.

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

    Directory of Open Access Journals (Sweden)

    Hongying Dong

    2014-12-01

    Full Text Available In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete’s compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

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

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

    2014-12-08

    In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete's compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

  13. Compressive strength evaluation of structural lightweight concrete by non-destructive ultrasonic pulse velocity method.

    Science.gov (United States)

    Bogas, J Alexandre; Gomes, M Glória; Gomes, Augusto

    2013-07-01

    In this paper the compressive strength of a wide range of structural lightweight aggregate concrete mixes is evaluated by the non-destructive ultrasonic pulse velocity method. This study involves about 84 different compositions tested between 3 and 180 days for compressive strengths ranging from about 30 to 80 MPa. The influence of several factors on the relation between the ultrasonic pulse velocity and compressive strength is examined. These factors include the cement type and content, amount of water, type of admixture, initial wetting conditions, type and volume of aggregate and the partial replacement of normal weight coarse and fine aggregates by lightweight aggregates. It is found that lightweight and normal weight concretes are affected differently by mix design parameters. In addition, the prediction of the concrete's compressive strength by means of the non-destructive ultrasonic pulse velocity test is studied. Based on the dependence of the ultrasonic pulse velocity on the density and elasticity of concrete, a simplified expression is proposed to estimate the compressive strength, regardless the type of concrete and its composition. More than 200 results for different types of aggregates and concrete compositions were analyzed and high correlation coefficients were obtained.

  14. Uniaxial Compressive Properties of Ultra High Toughness Cementitious Composite

    Institute of Scientific and Technical Information of China (English)

    CAI Xiangrong; XU Shilang

    2011-01-01

    Uniaxial compression tests were conducted to characterize the main compressive performance of ultra high toughness cementitious composite(UHTCC)in terms of strength and toughness and to obtain its stress-strain relationships.The compressive strength investigated ranges from 30 MPa to 60 MPa.Complete stress-strain curves were directly obtained,and the strength indexes,including uniaxial compressive strength,compressive strain at peak stress,elastic modulus and Poisson's ratio,were calculated.The comparisons between UHTCC and matrix were also carried out to understand the fiber effect on the compressive strength indexes.Three dimensionless toughness indexes were calculated,which either represent its relative improvement in energy absorption capacity because of fiber addition or provide an indication of its behavior relative to a rigid-plastic material.Moreover,two new toughness indexes,which were named as post-crack deformation energy and equivalent compressive strength,were proposed and calculated with the aim at linking up the compressive toughness of UHTCC with the existing design concept of concrete.The failure mode was also given.The study production provides material characteristics for the practical engineering application of UHTCC.

  15. Experimental study of high volume fly ash pumping concrete compressive strength early%大掺量粉煤灰泵送混凝土早期抗压强度的试验研究

    Institute of Scientific and Technical Information of China (English)

    刘思海; 侍克斌; 吴福飞

    2014-01-01

    通过理论分析和试验,研究了大掺量粉煤灰对混凝土早期抗压强度及成本的影响。试验所选用的胶凝材料总量为375 kg,以0~55%的粉煤灰替代水泥,减水剂的掺量固定为1.0%,引气剂的掺量固定为1.2‱。通过坍落度及不同龄期抗压强度等对比分析粉煤灰掺量对混凝土和易性及早期强度的影响。结果表明,混凝土早期抗压强度及成本随着粉煤灰掺量的增大而逐渐减小,运用粉煤灰等质量代替水泥(P·O 42.5级水泥)可配制出28 d抗压强度为20 MPa以上,成本大大降低的大掺量粉煤灰混凝土。研究的结论为新疆地区粉煤灰的应用提供了有效途径,有助于制备高性能混凝土。%Through theoretical analysis and test,studied the effect of high volume fly ash on concrete compressive strength and cost. To-tal cementitious materials test for the selected 375 kg,with 0~55%fly ash instead of cement,the amount of superplasticizer was fixed at 1%,dosage of air entraining agent was fixed at 1.2‱.Through the slump and compressive strength of comparative analysis of the influence of fly ash on concrete workability and early strength. The results showed that ,the concrete compressive strength and cost decreased gradu-ally with the increase in the amount of fly ash,fly ash and other quality instead of using cement (42.5 ordinary portland cement)can be made by 28 d compressive strength was more than 20 MPa,a large amount of fly ash can reduce the cost of concrete. Provided an effective way for research conclusion was the application of fly ash in Xinjiang ,contributed to the preparation of high performance concrete.

  16. An investigation of the compressive strength of Kevlar 49/epoxy composites

    Science.gov (United States)

    Kulkarni, S. V.; Rosen, B. W.; Rice, J. S.

    1975-01-01

    Tests were performed to evaluate the effect of a wide range of variables including matrix properties, interface properties, fiber prestressing, secondary reinforcement, and others on the ultimate compressive strength of Kevlar 49/epoxy composites. Scanning electron microscopy is used to assess the resulting failure surfaces. In addition, a theoretical study is conducted to determine the influence of fiber anisotropy and lack of perfect bond between fiber and matrix on the shear mode microbuckling. The experimental evaluation of the effect of various constituent and process characteristics on the behavior of these unidirectional composites in compression did not reveal any substantial increase in strength. However, theoretical evaluations indicate that the high degree of fiber anisotropy results in a significant drop in the predicted stress level for internal instability. Scanning electron microscope data analysis suggests that internal fiber failure and smooth surface debonding could be responsible for the measured low compressive strengths.

  17. Benefits of Sealed-Curing on Compressive Strength of Fly Ash-Based Geopolymers

    Directory of Open Access Journals (Sweden)

    Sujeong Lee

    2016-07-01

    Full Text Available There is no standardized procedure for producing geopolymers; therefore, many researchers develop their own procedures for mixing and curing to achieve good workability and strength development. The curing scheme adopted is important in achieving maximum performance of resultant geopolymers. In this study, we evaluated the impact of sealed and unsealed curing on mechanical strength of geopolymers. Fly ash-based geopolymers cured in sealed and unsealed moulds clearly revealed that retention of water during curing resulted in superior strength development. The average compressive strength of sealed-cured geopolymers measured after 1 day of curing was a modest 50 MPa, while after 7 day curing the average compressive strength increased to 120~135 MPa. In the unsealed specimens the average compressive strength of geopolymers was lower; ranging from 60 to 90 MPa with a slight increase as the curing period increased. Microcracking caused by dehydration is postulated to cause the strength decrease in the unsealed cured samples. These results show that water is a crucial component for the evolution of high strength three-dimensional cross-linked networks in geopolymers.

  18. Reliable evaluation method of quality control for compressive strength of concrete

    Institute of Scientific and Technical Information of China (English)

    CHEN Kuen-suan; SUNG Wen-pei; SHIH Ming-hsiang

    2005-01-01

    Concrete in reinforced concrete structure (RC) is generally under significant compressive stress load. To guarantee required quality and ductility, various tests have to be conducted to measure the concrete's compressive strength based on ACI(American Concrete Institute) code. Investigations of recent devastating collapses of structures around the world showed that some of the collapses directly resulted from the poor quality of the concrete. The lesson learned from these tragedies is that guaranteeing high quality of concrete is one of the most important factors ensuring the safety of the reinforced concrete structure.In order to ensure high quality of concrete, a new method for analyzing and evaluating the concrete production process is called for.In this paper, the indices of fit and stable degree are proposed as basis to evaluate the fitness and stability of concrete's compressive strength. These two indices are combined to define and evaluate the quality index of the compressive strength of concrete. Principles of statistics are used to derive the best estimators of these indices. Based on the outcome of the study, a concrete compressive strength quality control chart is proposed as a tool to help the evaluation process. Finally, a new evaluation procedure to assess the quality control capability of the individual concrete manufacturer is also proposed.

  19. Study on conversion relationships of compressive strength indexes for recycled lightweight aggregate concrete

    Science.gov (United States)

    Zhang, Xiang-gang; Yang, Jian-hui; Kuang, Xiao-mei

    2017-01-01

    In order to study cube compressive strength and axial compressive strength of recycled lightweight aggregate concrete(RLAC), and conversion relationship between the two, with the replacement rate of recycled lightweight coarse aggregate as change parameters, 15 standard cube test specimens and 15 standard prism test specimens were produced to carry out the test. Then compressive strength of test specimens were measured, and the law of different replacement rate of recycled lightweight coarse aggregate influencing compressive strength of RLAC was analyzed, as the method of statistical regression adopted, the conversion relationships between of cube compressive strength and axial compressive strength of RLAC was obtained. It is shown that compressive strength of RLAC are lower than compressive strength of ordinary concrete; and that compressive strength of RLAC gradually decreases as replacement rate of recycled lightweight coarse aggregate increases; as well as, the conversion relationship between axial compressive strength and cube compressive strength of RLAC is different from ordinary concrete; based on the experimental data, conversion relationship formula between compressive strength indexes of RLAC was established. It is suggested that the replacement rate of recycled lightweight aggregate should be controlled within 25%.

  20. The impact of water content and ionic diffusion on the uniaxial compressive strength of shale

    Directory of Open Access Journals (Sweden)

    Talal AL-Bazali

    2013-12-01

    Finally, the impact of ionic diffusion on the compressive strength of shale was carried out in the absence of both chemical osmosis and capillary forces. Results show that the invasion of sodium and calcium ions into shale reduced its compressive strength considerably while the invasion of potassium ions enhanced its compressive strength.

  1. Scaling of compression strength in disordered solids: metallic foams

    Directory of Open Access Journals (Sweden)

    J. Kováčik

    2016-03-01

    Full Text Available The scaling of compression strength with porosity for aluminium foams was investigated. The Al 99.96, AlMg1Si0.6 and AlSi11Mg0.6 foams of various porosity, sample size with and without surface skin were tested in compression. It was observed that the compression strength of aluminium foams scales near the percolation threshold with Tf ≈ 1.9 - 2.0 almost independently on the matrix alloy, sample size and presence of surface skin. The difference of the obtained values of Tf to the theoretical estimate of Tf = 2.64 ± 0.3 by Arbabi and Sahimi and to Ashby estimate of 1.5 was explained using an analogy with the Daoud and Coniglio approach to the scaling of the free energy of sol-gel transition. It leads to the finding that, there are two different universality classes for the critical exponent Tf: when the stretching forces dominate Tf = f = 2.1, respectively when bending forces prevail Tf = .d = 2.64 seems to be valid. Another possibility is the validity of relation Tf ≤ f which varies only according to the universality class of modulus of elasticity in foam.

  2. Effect of In-Situ Curing on Compressive Strength of Reactive Powder Concrete

    Directory of Open Access Journals (Sweden)

    Bali Ika

    2016-01-01

    Full Text Available A development of Reactive Powder Concrete (RPC currently is the use of quartz powder as a stabilizing agent with the content to cement ratio of 30% and steam curing method in an autoclave temperature of 250ºC which produced a high compressive strength of 180 MPa. That RPC can be generated due to one reason for using the technique of steam curing in an autoclave in the laboratory. This study proposes in-situ curing method in order the curing can be applied in the field and with a reasonable compressive strength results of RPC. As the benchmarks in this study are the curing methods in laboratory that are steam curing of 90°C for 8 hours (C1, and water curing for 28 days (C2. For the in-situ curing methods that are covering with tarpaulins and flowed steam of 3 hours per day for 7 days (C3, covering with wet sacks for 28 days (C4, and covering with wet sacks for 28 days for specimen with unwashed sand as fine aggregate (C5. The comparison of compressive strength of the specimens in this study showed compressive strength of RPC with in-situ steam curing (101.64 MPa close to the compressive strength of RPC with steam curing in the laboratory with 8.2% of different. While in-situ wet curing compared with the water curing in laboratory has the different of 3.4%. These results indicated that the proposed in-situ curing methods are reasonable good in term of the compressive strength that can be achieved.

  3. Strength Modeling of High-Strength Concrete with Hybrid Fibre Reinforcement

    Directory of Open Access Journals (Sweden)

    A. Ravichandran

    2009-01-01

    Full Text Available The low tensile strength and limited ductility, the unavoidable deficiency, of concrete can be overcome by the addition of fibres. High strength concrete (HSC of 60 MPa containing hybrid fibres, combination of steel and polyolefin fibres, at different volume fraction of 0.5, 1.0, 1.5 and 2.0% were compared in terms of compressive, splitting tensile strength and flexural properties with HSC containing no fibres. Test results showed that the fibres when used in hybrid form could result in enhanced flexural toughness compared to steel fibre reinforced concrete [HSFRC]. The compressive strength of the fibre-reinforced concrete reached maximum at 1.5% volume fractions and the splitting tensile strength and modulus of rupture improved with increasing volume fraction. Strength models were established to predict the compressive and splitting tensile strength and modulus of rupture of the fibre-reinforced concrete. The models give prediction matching the measurements.

  4. Oxidation Behavior of Matrix Graphite and Its Effect on Compressive Strength

    Directory of Open Access Journals (Sweden)

    Xiangwen Zhou

    2017-01-01

    Full Text Available Matrix graphite (MG with incompletely graphitized binder used in high-temperature gas-cooled reactors (HTGRs is commonly suspected to exhibit lower oxidation resistance in air. In order to reveal the oxidation performance, the oxidation behavior of newly developed A3-3 MG at the temperature range from 500 to 950°C in air was studied and the effect of oxidation on the compressive strength of oxidized MG specimens was characterized. Results show that temperature has a significant influence on the oxidation behavior of MG. The transition temperature between Regimes I and II is ~700°C and the activation energy (Ea in Regime I is around 185 kJ/mol, a little lower than that of nuclear graphite, which indicates MG is more vulnerable to oxidation. Oxidation at 550°C causes more damage to compressive strength of MG than oxidation at 900°C. Comparing with the strength of pristine MG specimens, the rate of compressive strength loss is 77.3% after oxidation at 550°C and only 12.5% for oxidation at 900°C. Microstructure images of SEM and porosity measurement by Mercury Porosimetry indicate that the significant compressive strength loss of MG oxidized at 550°C may be attributed to both the uniform pore formation throughout the bulk and the preferential oxidation of the binder.

  5. An appropriate relationship between flexural strength and compressive strength of palm kernel shell conc

    Directory of Open Access Journals (Sweden)

    Ibrahim Tunde Yusuf

    2016-06-01

    Full Text Available This paper presents the determination of an appropriate compressive–flexural strength model of palm kernel shell concrete (PKSC. The direct and indirect Ultrasonic Pulse Velocity (UPV measurements, with respective to mechanical properties of compression (cube and flexural (slab elements, of concrete at various mixes and water/cement (w/c ratios were made. A total of 225 cubes and 15 slabs of the PKSC were casted for nominal mixes of 1:1:1, 1:1:2 and 1:11/2:3, and varying (w/c ratios of 0.3–0.7 at interval of 0.1. The test elements were cured for 3, 7, 14, 28, 56 and 91 days in water at laboratory temperature. The elements were then subjected to nondestructive testing using the Pundit apparatus for determination of direct ultrasonic wave velocity and the elastic modulus at the various ages. The cubes were subsequently subjected to destructive compressive test. The 28-day compressive strength–UPV and strength–age statistical relationships at w/c ratio of 0.5 determined from the velocity–strength data set in linear, power, logarithm, exponential and polynomial trend forms. The polynomial trend line in the form y = aln(x at R2 value of 0.989, found appropriate, among others, was proposed for the formulation of the compressive strength–flexural strength model of PKSC at w/c ratio of 0.5.

  6. Size effect on cubic and prismatic compressive strength of cement paste

    Institute of Scientific and Technical Information of China (English)

    苏捷; 叶缙垚; 方志; 赵明华

    2015-01-01

    A series of compression tests were conducted on 150 groups of cement paste specimens with side lengths ranging from 40 mm to 200 mm. The specimens include cube specimens and prism specimens with height to width ratio of 2. The experiment results show that size effect exists in the cubic compressive strength and prismatic compressive strength of the cement paste, and larger specimens resist less in terms of strength than smaller ones. The cubic compressive strength and the prismatic compressive strength of the specimens with side length of 200 mm are respectively about 91% and 89% of the compressive strength of the specimens with the side length of 40 mm. Water to binder ratio has a significant influence on the size effect of the compressive strengths of the cement paste. With a decrease in the water to binder ratio, the size effect is significantly enhanced. When the water to binder ratio is 0.2, the size effects of the cubic compressive strength and the prismatic compressive strength of the cement paste are 1.6 and 1.4 times stronger than those of a water to binder ratio of 0.6. Furthermore, a series of formulas are proposed to calculate the size effect of the cubic compressive strength and the prismatic compressive strength of cement paste, and the results of the size effect predicted by the formulas are in good agreement with the experiment results.

  7. High-strength mineralized collagen artificial bone

    Science.gov (United States)

    Qiu, Zhi-Ye; Tao, Chun-Sheng; Cui, Helen; Wang, Chang-Ming; Cui, Fu-Zhai

    2014-03-01

    Mineralized collagen (MC) is a biomimetic material that mimics natural bone matrix in terms of both chemical composition and microstructure. The biomimetic MC possesses good biocompatibility and osteogenic activity, and is capable of guiding bone regeneration as being used for bone defect repair. However, mechanical strength of existing MC artificial bone is too low to provide effective support at human load-bearing sites, so it can only be used for the repair at non-load-bearing sites, such as bone defect filling, bone graft augmentation, and so on. In the present study, a high strength MC artificial bone material was developed by using collagen as the template for the biomimetic mineralization of the calcium phosphate, and then followed by a cold compression molding process with a certain pressure. The appearance and density of the dense MC were similar to those of natural cortical bone, and the phase composition was in conformity with that of animal's cortical bone demonstrated by XRD. Mechanical properties were tested and results showed that the compressive strength was comparable to human cortical bone, while the compressive modulus was as low as human cancellous bone. Such high strength was able to provide effective mechanical support for bone defect repair at human load-bearing sites, and the low compressive modulus can help avoid stress shielding in the application of bone regeneration. Both in vitro cell experiments and in vivo implantation assay demonstrated good biocompatibility of the material, and in vivo stability evaluation indicated that this high-strength MC artificial bone could provide long-term effective mechanical support at human load-bearing sites.

  8. Characterization of the Compressive Strength of Sandcrete Blocks in ...

    African Journals Online (AJOL)

    AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... are high and they indicate very poor quality control in the production processes. ... the strength and effectiveness of sandcrete blocks production in Nigeria are made.

  9. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2013-01-01

    Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and

  10. Permeability, porosity and compressive strength of self-compacting concrete

    Directory of Open Access Journals (Sweden)

    Valcuende, M.O.

    2005-12-01

    Full Text Available Most deterioration affecting the durability of self-compacting concrete structures is mediated by water penetration in the concrete, a condition related to its porous structure. The present study analyzes these two factors. To this end, two types of concrete were prepared, a self-compacting and a traditional vibrated concrete, with different W/C ratios and different types of cement. The results of low-pressure water testing to evaluate permeability and analyses to determine compressive strength and pore size distribution showed that self-compacting concrete has lower capillary porosity than traditional concrete, which would explain its greater resistance to water penetration. Such concrete likewise reached higher strength values, except where large proportions of lime powder with low sand equivalents were used in its manufacture, when lower strength was recorded. Lastly, the depth of water penetration and compressive strength were found to be linearly correlated. That correlation was seen to depend, in turn, on the type of concrete, since for any given strength level, self-compacting concrete was less permeable than the traditional material.

    En este trabajo experimental se estudia la penetración de agua en hormigones autocompactables, analizando al mismo tiempo su estructura porosa, pues gran parte de los procesos de deterioro que afectan a la durabilidad de las estructuras están condicionados por estos dos aspectos. Para ello se han fabricado dos tipos de hormigones, uno autocompactable y otro tradicional vibrado, con diferentes relaciones A/C y distintos tipos de cemento. Tras determinar la permeabilidad al agua bajo presión, la resistencia a compresión y las distribuciones de tamaño de poro, los resultados obtenidos ponen de manifiesto que los hormigones autocompactables presentan menor porosidad capilar que los tradicionales, lo que les confiere mejores prestaciones frente a la penetración de agua. Asimismo, dichos hormigones

  11. Coefficient αcc in design value of concrete compressive strength

    Directory of Open Access Journals (Sweden)

    Goleš Danica

    2016-01-01

    Full Text Available Coefficient αcc introduces the effects of rate and duration of loading on compressive strength of concrete. These effects may be partially or completely compensated by the increase in concrete strength over time. Selection of the value of this coefficient, in recommended range between 0.8 and 1.0, is carried out through the National Annexes to Eurocode 2. This paper presents some considerations related to the introduction of this coefficient and its value adopted in some European countries. The article considers the effect of the adoption of conservative value αcc=0.85 on design value of compressive and flexural resistance of rectangular cross-section made of normal and high strength concrete. It analyzes the influence of different values of coefficient αcc on the area of reinforcement required to achieve the desired resistance of cross-section.

  12. Retention Strength after Compressive Cyclic Loading of Five Luting Agents Used in Implant-Supported Prostheses

    Directory of Open Access Journals (Sweden)

    Angel Alvarez-Arenal

    2016-01-01

    Full Text Available The purpose of this study was to evaluate and compare the retention strength of five cement types commonly used in implant-retained fixed partial dentures, before and after compressive cyclic loading. In five solid abutments screwed to 5 implant analogs, 50 metal Cr-Ni alloy copings were cemented with five luting agents: resin-modified glass ionomer (RmGI, resin composite (RC, glass ionomer (GI, resin urethane-based (RUB, and compomer cement (CC. Two tensile tests were conducted with a universal testing machine, one after the first luting of the copings and the other after 100,000 cycles of 100 N loading at 0.72 Hz. The one way ANOVA test was applied for the statistical analysis using the post hoc Tukey test when required. Before and after applying the compressive load, RmGI and RC cement types showed the greatest retention strength. After compressive loading, RUB cement showed the highest percentage loss of retention (64.45%. GI cement recorded the lowest retention strength (50.35 N and the resin composite cement recorded the highest (352.02 N. The type of cement influences the retention loss. The clinician should give preference to lower retention strength cement (RUB, CC, and GI if he envisages any complications and a high retention strength one (RmGI, RC for a specific clinical situation.

  13. Influence of pore structure on compressive strength of cement mortar.

    Science.gov (United States)

    Zhao, Haitao; Xiao, Qi; Huang, Donghui; Zhang, Shiping

    2014-01-01

    This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure.

  14. Engineering properties of high strength lightweight concrete

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-08-01

    The strength to weight ratio of high strength lightweight concrete is not its only advantage. The artificial lightweight aggregate combines physically and, to a lesser extent, chemically with the surrounding cement matrix to produce an impermeable and durable concrete. The engineering properties of the concrete are sensitive to the proportions and nature of its constituents, and to its production methods. Supplementary cementing materials and chemical admixtures are used to develop the increased strength and durability. Thermal movements, shrinkage and creep are within workable limits. Fatigue resistance is probably at least as good as that achieved by equivalent strength normal density concretes but there is limited data on this topic. Deleterious effects of admixtures supplied in high dosages have not been identified but neither have they been investigated. The relationship between the tensile strength of the material and its uniaxial compressive strength is not robust. The shear capacity of structural elements is not adequately covered by most existing design codes. In common with all concretes, the stability of high strength lightweight concrete is reduced when water retained within it freezes or vaporises. A satisfactory freeze thaw behaviour can be readily achieved but, under fire conditions, the impermeability of the cement matrix limits the venting of water vapour at the concrete surface. Explosive failures can result. (Author)

  15. 信息动态%Size Effect on Strength of Ultra-high Strength Concrete RPC

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Reactive Powder Concrete (RPC)is a new kind of ultra-high strength cement based composite with excellent mechanics performance and durability. In order to make RPC used in structural engineering effectively,size effect on strength of the ultra high strength concrete RPC specimen is experimental studied and the mechanism is analyzed in this paper. Test results show that if the 4 cm cube compressive strength is the control strength,conversion coefficients of 10 em cube compressive strength at 150 MPa and 200 MPa grade are 0.81 and 0.76 respectively; conversion coefficients of 10 cm× 10 cm× 30 cm prism compressive strength at 150 MPa and 200 MPa grade are 0.71 and 0. 63 respectively; the size effect conversion coefficient tends to decrease with the increase of control strength, the larger the specimen size, the lower the compressive strength. RPC is a typical brittle material. It extends instability quickly after cracking;damage concentrated in the local area,and therefore appears higher size effect.

  16. Developing an artificial neural network model for predicting concrete’s compression strength and electrical resistivity

    Directory of Open Access Journals (Sweden)

    Juan Manuel Lizarazo Marriaga

    2010-04-01

    Full Text Available The present study was conducted for predicting the compressive strength of concrete based on unit weight ultrasonic and pulse velocity (UPV for 41 different concrete mixtures. This research emerged from the need for a rapid test for predicting concrete’s compressive strength. The research was also conducted for predicting concrete’s electrical resistivity based on unit weight ultrasonic, pulse velocity (UPV and compressive strength with the same mixes. The prediction was made using simple regression analysis and artificial neural networks. The results revealed that artificial neural networks can be used for effectively predicting compressive strength and electrical resistivity.

  17. Mechanical properties of high-strength concrete

    Science.gov (United States)

    Mokhtarzadeh, Alireza

    This report summarizes an experimental program conducted to investigate production techniques and mechanical properties of high strength concrete in general and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. Test variables included total amount and composition of cementitious material (portland cement, fly ash, and silica fume), type and brand of cement, type of silica fume (dry densified and slurry), type and brand of high-range water-reducing admixture, type of aggregate, aggregate gradation, maximum aggregate size, and curing. Tests were conducted to determine the effects of these variables on changes in compressive strength and modulus of elasticity over time, splitting tensile strength, modulus of rupture, creep, shrinkage, and absorption potential (as an indirect indicator of permeability). Also investigated were the effects of test parameters such as mold size, mold material, and end condition. Over 6,300 specimens were cast from approximately 140 mixes over a period of 3 years.

  18. 钢管高强混凝土压弯构件滞回性能的研究%Research on hysteretic behavior of high strength concrete filled steel tubular member under compression and bending

    Institute of Scientific and Technical Information of China (English)

    王湛; 甄永辉

    2000-01-01

    In this paper, the force-displacement hysteretic loops of high strength concrete filled steel tubular members under compression and bending are calculated using element method with a steel constitutive model which is suitable for multiaxial cyclic loading and for a concrete modified bounding surface model for multiaxial cyclic compression. Six new tests were carried out on steel tubes filled with concrete with a cube strength of 77N/mm2. The theoretical lateral force-displacement hysteretic loops are compared with these tests and tests by other experimenters and the results are discussed.%本文根据适用于三向周期受力的钢材本构关系模型,和适用于三向周期受力改进的混凝土本构关系的边界面模型,采用有限元法对钢管高强混凝土压弯构件的荷载-位移滞回曲线进行了理论分析,并进行了6个核心混凝土的强度为77N/mm2的钢管高强混凝土压弯构件滞回性能的试验研究。将理论分析和本试验研究及其他试验研究结果进行了对比,分析了荷载-位移滞回曲线的特点。

  19. Strength of Tubular Joints Made by Electromagnetic Compression at Quasistatic and Cyclic Loading

    OpenAIRE

    Barreiro, P.; Beerwald, C.; Homberg, W.; Kleiner, M.; Löhe, D.; Marré, M.; Schulze, V.

    2006-01-01

    Electromagnetic compression of tubular profiles with high electrical conductivity is an innovative joining process for lightweight structures. The components are joined using pulsed magnetic fields which apply radial pressures of up to 200 MPa to tubular workpieces, causing a symmetric reduction of the diameter with typical strain rates of up to 10^4 sec^(-1). This process avoids any surface damage of the workpiece because there is no contact between component and forming tool. The strength o...

  20. FATIGUE STRENGTH OF HIGH-STRENGTH STEEL,

    Science.gov (United States)

    coldhardened by deforming to 83%. It was found that it has low static notch sensitivity (lower than that of heat-treated steels), that static strength ...is raised appreciably by increased cold plastic deformation, and that its fatigue strength is raised substantially by mechanical polishing. (Author)

  1. Confined High Strength Concrete Columns: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Jagannathan Saravanan

    2010-01-01

    Full Text Available Problem statement: An experimental study on GFRP confined high strength concrete columns has been carried out with a view to evaluate its performances under uni-axial compression in terms of load and deformation capacity. Approach: High strength concrete columns strengthened with different configuration and stiffness of GFRP wraps were tested under axial compression until failure. Their response evaluated at different load levels. Results: The test results clearly indicated GFRP wrapped high strength concrete columns exhibit enhances performance. Conclusion: The study concluded that the three GFRP materials attempted UDC GFRP provided the maximum benefit with respect to load and deformation.

  2. Mechanical properties of Concrete with SAP. Part I: Development of compressive strength

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jespersen, Morten H. Seneka; Jensen, Ole Mejlhede

    2010-01-01

    The development of mechanical properties has been studied in a test program comprising 15 different concrete mixes with 3 different w/c ratios and different additions of superabsorbent polymers (SAP). The degree of hydration is followed for 15 corresponding paste mixes. This paper concerns...... compressive strength. It shows that results agree well with a model based on the following: 1. Concrete compressive strength is proportional to compressive strength of the paste phase 2. Paste strength depends on gel space ratio, as suggested by Powers 3. The influence of air voids created by SAP...... on compressive strength can be accounted for in the same way as when taking the air content into account in Bolomeys formula. The implication of the model is that at low w/c ratios (w/c SAP additions, SAP increases the compressive strength at later ages (from 3 days after casting and onwards...

  3. Mechanical properties of Concrete with SAP. Part I: Development of compressive strength

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jespersen, Morten H. Seneka; Jensen, Ole Mejlhede

    2010-01-01

    The development of mechanical properties has been studied in a test program comprising 15 different concrete mixes with 3 different w/c ratios and different additions of superabsorbent polymers (SAP). The degree of hydration is followed for 15 corresponding paste mixes. This paper concerns...... compressive strength. It shows that results agree well with a model based on the following: 1. Concrete compressive strength is proportional to compressive strength of the paste phase 2. Paste strength depends on gel space ratio, as suggested by Powers 3. The influence of air voids created by SAP...... on compressive strength can be accounted for in the same way as when taking the air content into account in Bolomeys formula. The implication of the model is that at low w/c ratios (w/c SAP additions, SAP increases the compressive strength at later ages (from 3 days after casting and onwards...

  4. An Exploratory Compressive Strength Of Concrete Containing Modified Artificial Polyethylene Aggregate (MAPEA)

    Science.gov (United States)

    Hadipramana, J.; Mokhatar, S. N.; Samad, A. A. A.; Hakim, N. F. A.

    2016-11-01

    Concrete is widely used in the world as building and construction material. However, the constituent materials used in concrete are high cost when associated with the global economic recession. This exploratory aspires to have an alternative source of replacing natural aggregate with plastic wastes. An investigation of the Modified Artificial Polyethylene Aggregate (MAPEA) as natural aggregate replacement in concrete through an experimental work was conducted in this study. The MAPEA was created to improve the bonding ability of Artificial Polyethylene Aggregate (APEA) with the cement paste. The concrete was mixed with 3%, 6%, 9%, and 12% of APEA and MAPEA for 14 and 28 curing days, respectively. Furthermore, the compressive strength test was conducted to find out the optimum composition of MAPEA in concrete and compared to the APEA concrete. Besides, this study observed the influence and behaviour of MAPEA in concrete. Therefore, the Scanning Electron Microscopy was applied to observe the microstructure of MAPEA and APEA concrete. The results showed the use of high composition of an artificial aggregate resulted inferior strength on the concrete and 3% MAPEA in the concrete mix was highest compressive strength than other content. The modification of APEA (MAPEA) concrete increased its strength due to its surface roughness. However, the interfacial zone cracking was still found and decreased the strength of MAPEA concrete especially when it was age 28 days.

  5. Residual compressive surface stress increases the bending strength of dental zirconia.

    Science.gov (United States)

    Inokoshi, Masanao; Zhang, Fei; Vanmeensel, Kim; De Munck, Jan; Minakuchi, Shunsuke; Naert, Ignace; Vleugels, Jozef; Van Meerbeek, Bart

    2017-04-01

    To assess the influence of surface treatment and thermal annealing on the four-point bending strength of two ground dental zirconia grades. Fully-sintered zirconia specimens (4.0×3.0×45.0mm(3)) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/Al2O3 zirconia (ZirTough, Kuraray Noritake) were subjected to four surface treatments: (1) 'GROUND': all surfaces were ground with a diamond-coated grinding wheel on a grinding machine; (2) 'GROUND+HEAT': (1) followed by annealing at 1100°C for 30min; (3) 'GROUND+Al2O3 SANDBLASTED': (1) followed by sandblasting using Al2O3; (4) 'GROUND+CoJet SANDBLASTED': (1) followed by tribochemical silica (CoJet) sandblasting. Micro-Raman spectroscopy was used to assess the zirconia-phase composition and potentially induced residual stress. The four-point bending strength was measured using a universal material-testing machine. Weibull analysis revealed a substantially higher Weibull modulus and slightly higher characteristic strength for ZirTough (Kuraray Noritake) than for LAVA Plus (3M ESPE). For both zirconia grades, the 'GROUND' zirconia had the lowest Weibull modulus in combination with a high characteristic strength. Sandblasting hardly changed the bending strength but substantially increased the Weibull modulus of the ground zirconia, whereas a thermal treatment increased the Weibull modulus of both zirconia grades but resulted in a significantly lower bending strength. Micro-Raman analysis revealed a higher residual compressive surface stress that correlated with an increased bending strength. Residual compressive surface stress increased the bending strength of dental zirconia. Thermal annealing substantially reduced the bending strength but increased the consistency (reliability) of 'GROUND' zirconia. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Effects of Elevated Temperatures on the Compressive Strength Capacity of Concrete Cylinders Confined with FRP Sheets: An Experimental Investigation

    Directory of Open Access Journals (Sweden)

    Sherif El-Gamal

    2015-01-01

    Full Text Available Due to their high strength, corrosion resistance, and durability, fiber reinforced polymers (FRP are very attractive for civil engineering applications. One of these applications is the strengthening of concrete columns with FRP sheets. The performance of this strengthening technique at elevated temperature is still questionable and needs more investigations. This research investigates the effects of exposure to high temperatures on the compressive strength of concrete cylinders wrapped with glass and carbon FRP sheets. Test specimens consisted of 30 unwrapped and 60 wrapped concrete cylinders. All specimens were exposed to temperatures of 100, 200, and 300°C for periods of 1, 2, and 3 hours. The compressive strengths of the unwrapped concrete cylinders were compared with their counterparts of the wrapped cylinders. For the unwrapped cylinders, test results showed that the elevated temperatures considered in this study had almost no effect on their compressive strength; however, the wrapped specimens were significantly affected, especially those wrapped with GFRP sheets. The compressive strength of the wrapped specimens decreased as the exposure period and the temperature level increased. After three hours of exposure to 300°C, a maximum compressive strength loss of about 25.3% and 37.9%, respectively, was recorded in the wrapped CFRP and GFRP specimens.

  7. Development of optimization models for the set behavior and compressive strength of sodium activated geopolymer pastes

    Science.gov (United States)

    Fillenwarth, Brian Albert

    As large countries such as China begin to industrialize and concerns about global warming continue to grow, there is an increasing need for more environmentally friendly building materials. One promising material known as a geopolymer can be used as a portland cement replacement and in this capacity emits around 67% less carbon dioxide. In addition to potentially reducing carbon emissions, geopolymers can be synthesized with many industrial waste products such as fly ash. Although the benefits of geopolymers are substantial, there are a few difficulties with designing geopolymer mixes which have hindered widespread commercialization of the material. One such difficulty is the high variability of the materials used for their synthesis. In addition to this, interrelationships between mix design variables and how these interrelationships impact the set behavior and compressive strength are not well understood. A third complicating factor with designing geopolymer mixes is that the role of calcium in these systems is not well understood. In order to overcome these barriers, this study developed predictive optimization models through the use of genetic programming with experimentally collected set times and compressive strengths of several geopolymer paste mixes. The developed set behavior models were shown to predict the correct set behavior from the mix design over 85% of the time. The strength optimization model was shown to be capable of predicting compressive strengths of geopolymer pastes from their mix design to within about 1 ksi of their actual strength. In addition to this the optimization models give valuable insight into the key factors influencing strength development as well as the key factors responsible for flash set and long set behaviors in geopolymer pastes. A method for designing geopolymer paste mixes was developed from the generated optimization models. This design method provides an invaluable tool for use in future geopolymer research as well as

  8. Prediction of potential compressive strength of Portland clinker from its mineralogy

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar; Justnes, H.

    2010-01-01

    Based on a statistical model first applied for prediction of compressive strength up to 28 d from the microstructure of Portland cement, potential compressive strength of clinker has been predicted from its mineralogy. The prediction model was evaluated by partial least squares regression. The mi...

  9. Dataset of long-term compressive strength of concrete with manufactured sand.

    Science.gov (United States)

    Ding, Xinxin; Li, Changyong; Xu, Yangyang; Li, Fenglan; Zhao, Shunbo

    2016-03-01

    This paper presents 186 groups compressive strength tests data of concrete with manufactured sand (MSC) in different curing age and 262 groups compressive strength tests data of MSC at 28 days collected from authors' experiments and other researches in China. Further interpretation and discussion were described in this issues.

  10. HIGH STRENGTH CONTROL RODS FOR NEUTRONIC REACTORS

    Science.gov (United States)

    Lustman, B.; Losco, E.F.; Cohen, I.

    1961-07-11

    Nuclear reactor control rods comprised of highly compressed and sintered finely divided metal alloy panticles and fine metal oxide panticles substantially uniformly distributed theretbrough are described. The metal alloy consists essentially of silver, indium, cadmium, tin, and aluminum, the amount of each being present in centain percentages by weight. The oxide particles are metal oxides of the metal alloy composition, the amount of oxygen being present in certain percentages by weight and all the oxygen present being substantially in the form of metal oxide. This control rod is characterized by its high strength and resistance to creep at elevated temperatures.

  11. Influencing factors of compressive strength of solidified inshore saline soil using SH lime-ash

    Institute of Scientific and Technical Information of China (English)

    覃银辉; 刘付华; 周琦

    2008-01-01

    Through unconfined compressive strength test,influencing factors on compressive strength of solidified inshore saline soil with SH lime-ash,ratio of lime-ash(1-K),quantity of lime-ash,age,degree of compression and salt content were studied.The results show that because inshore saline soil has special engineering characteristic,more influencing factors must be considered compared with ordinary soil for the perfect effect of solidifying.

  12. Preparing diopside nanoparticle scaffolds via space holder method: Simulation of the compressive strength and porosity.

    Science.gov (United States)

    Abdellahi, Majid; Najafinezhad, Aliakbar; Ghayour, Hamid; Saber-Samandari, Saeed; Khandan, Amirsalar

    2017-08-01

    In the present study, diopside nanopowders were prepared via mechanical milling with eggshell as the calcium source. The space holder method (compaction of ceramic powder and spacer) as one of the most important methods to produce ceramic/metal scaffolds was used to produce diopside scaffolds. For the first time, the effect of the spacer size on mechanical properties and porosity of the obtained scaffolds was experimentally discussed. According to the results obtained, the NaCl particles (as the spacer) with the size of 400-600µm maintained their original spherical shape during the compaction and sintering processes. As a new work, the most important parameters including the spacer type, spacer concentration, spacer size, and applied pressure were considered, and their effects on mechanical properties and porosity of diopside scaffolds were simulated. Gene Expression Programming (GEP), as one of the most branches of the artificial intelligence, was used for simulation process. By using the GEP, two equations were introduced to predict the compressive strength and porosity of the obtained scaffolds with the lowest error values. The 3D diagrams extracted from the model were used to evaluate the combined effect of the process parameters on the compressive strength and porosity of the scaffolds. The GEP model presented in this work has a very low level of error and a high level of the squared regression for predicting the compressive strength and porosity of diopside scaffolds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Making High-Tensile-Strength Amalgam Components

    Science.gov (United States)

    Grugel, Richard

    2008-01-01

    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams

  14. Effect of Cylinder Size on the Modulus of Elasticity and Compressive Strength of Concrete from Static and Dynamic Tests

    Directory of Open Access Journals (Sweden)

    Byung Jae Lee

    2015-01-01

    Full Text Available The primary objective of this study is to investigate the effects of cylinder size (150 by 300 mm and 100 by 200 mm on empirical equations that relate static elastic moduli and compressive strength and static and dynamic elastic moduli of concrete. For the purposes, two sets of one hundred and twenty concrete cylinders, 150 by 300 mm and 100 by 200 mm, were prepared from three different mixtures with target compressive strengths of 30, 35, and 40 MPa. Static and dynamic tests were performed at 4, 7, 14, and 28 days to evaluate compressive strength and static and dynamic moduli of cylinders. The effects of the two different cylinder sizes were investigated through experiments in this study and database collected from the literature. For normal strength concrete (≤40 MPa, the two different cylinder sizes do not result in significant differences in test results including experimental variability, compressive strength, and static and dynamic elastic moduli. However, it was observed that the size effect became substantial in high strength concrete greater than 40 MPa. Therefore, special care is still needed to compare the static and dynamic properties of high strength concrete from the two different cylinder sizes.

  15. Compressive Strength Evaluation in Brazed ZrO2/Ti6Al4V Joints Using Finite Element Analysis

    Science.gov (United States)

    Sharma, Ashutosh; Kee, Se Ho; Jung, Flora; Heo, Yongku; Jung, Jae Pil

    2016-05-01

    This study aims to synthesize and evaluate the compressive strength of the ZrO2/Ti-6Al-4V joint brazed using an active metal filler Ag-Cu-Sn-Ti, and its application to dental implants assuring its reliability to resist the compressive failure in the actual oral environment. The brazing was performed at a temperature of 750 °C for 30 min in a vacuum furnace under 5 × 10-6 Torr atmosphere. The microstructure of the brazed joint showed the presence of an Ag-rich matrix and a Cu-rich phase, and Cu-Ti intermetallic compounds were observed along the Ti-6Al-4V bonded interface. The compressive strength of the brazed ZrO2/Ti-6Al-4V joint was measured by EN ISO 14801 standard test method. The measured compressive strength of the joint was ~1477 MPa—a value almost five times that of existing dental cements. Finite element analysis also confirmed the high von Mises stress values. The compressive strains in the samples were found concentrated near the Ti-6Al-4V position, matching with the position of the real fractured sample. These results suggest extremely significant compressive strength in ZrO2/Ti-6Al-4V joints using the Ag-Cu-Sn-Ti filler. It is believed that a highly reliable dental implant can be processed and designed using the results of this study.

  16. Early Age Compressive Strength of Pastes by Electrical Resistivity Method and Maturity Method

    Institute of Scientific and Technical Information of China (English)

    XIAO Lianzhen; WEI Xiaosheng

    2011-01-01

    The compressive strength development of Portland cement pastes was investigated by the electrical resistivity method and the maturity method.The experiments were carried out on the cement pastes with different water-cement ratios at different curing temperatures.The results show that the application of the maturity method has limitation to obtain the strength.It is found that both of the compressive strength and the electrical resistivity follow hyperbolic trend for all the mixes.The hyperbolic equation of each mix is obtained to estimate the ultimate resistivity value which can probably be reached.The relationship between electrical resistivity and compressive strength of the cement pastes is established based on the test results and interpreted by the empirical Archie equation and a strength-porosity equation.The relationship between the electrical resistivity after temperature correction and the compressive strength was linear and independent of curing temperature and water-cement ratio.

  17. Stress-Strain Relationship of High-Strength Steel Fiber Reinforced Concrete in Compression%钢纤维高强混凝土单轴压缩下应力应变关系

    Institute of Scientific and Technical Information of China (English)

    严少华; 钱七虎; 孙伟; 尹放林

    2001-01-01

    在实际工程中推广应用钢纤维高强混凝土,要了解其基本力学性能.采用MTS815.03型液压伺服刚性压力试验机,对钢纤维含量为0~6%、抗压强度在65~120MPa范围的4种钢纤维高强混凝土,进行单轴压缩荷载作用下的应力应变全过程试验.结合试验给出全曲线的方程,并分析钢纤维对抗压强度、弹性模量、韧度、泊松比等的影响.试验表明,当钢纤维长度大于或接近于最大集料尺寸时,钢纤维高强混凝土具有较高的抗压强度和韧度,是一种优良的新型建筑材料.%It is necessary to research the basic mechanical performance inorder to use high-strength steel fiber reinforced concrete (HSFC) in practical engineering. Tests are conducted to characterize the stress-strain relationship of HSFC in compression by MTS815.03 rock testing machine. The concrete strength investigated ranges from 65 to 120 MPa and the volume fraction of steel fiber ranges from 0 to 6%. Based on the test data, an analytical model is proposed to generate the complete stress-strain curve for HSFC. The elastic modulus and toughness and Poisson’s ration of HSFC are also calculated in this paper. It is also proved by tests that HSFC is a good building material with high strength and high toughness when steel fibers are longer than the size of aggregate in concrete.

  18. Experimental study on ultimate bearing capacity of axially compressed high strength steel columns%高强钢焊接箱形柱轴心受压极限承载力试验研究

    Institute of Scientific and Technical Information of China (English)

    李国强; 王彦博,; 陈素文

    2012-01-01

    An experimental and theoretical study was presented on ultimate bearing capacity of axially compressed high strength steel columns. The experimental program included 7 welded box columns of 3 different cross sections which were welded with 11 mm-thick Q460 high strength steel plates made in China. The FEA models were built up according to measured sizes of members and tension coupon test results. And initial geometric imperfections and residual stress were taken into account in the FEA models. The experimental result shows that the stability coefficients of welded box columns of high strength steel are higher than the values of type c column curve in GB 50017--2003, and even higher than the values of type b curve for most of the specimens. However, due to the limited test result, the adoption of type b curve needs further verification. The FEA result agrees well with experimental result and could be a valid supplement of test data.%为了研究高强钢中厚板焊接箱形柱的极限承载力,以11 mm厚国产Q460高强钢中厚板制作了7个焊接箱形柱进行轴心受压试验。试件共包含宽厚比8、12、18三种截面,长细比分别为35、50、70。根据试件的实测尺寸、钢材的力学性能建立有限元模型,以初始缺陷的形式考虑了试件的初始挠度、初始偏心及焊接残余应力,分析预测了试件的极限承载力。试验结果表明,高强钢焊接箱形柱稳定系数采用GB 50017—2003《钢结构设计规范》中的c类截面柱子曲线偏保守,试验结果平均曲线更接近b类截面曲线,但仍需进一步验证。分析结果表明,考虑了初始缺陷的有限元模型可准确预测柱的极限承载力,可以作为试验数据的补充。

  19. The influence of biocalcification on soil-cement interlocking block compressive strength

    Directory of Open Access Journals (Sweden)

    Yoosathaporn, S.

    2015-01-01

    Full Text Available Description of the subject. Soil-cement interlocking block is used as the building block for many civil structures in Thailand. The addition of many alternative materials into interlocking block in order to improve compressive strength has been reported. However, there is currently no report on the influence of application of biocalcification or microbiologically induced calcite precipitation (MICP on interlocking block compressive strength. Objectives. This study aimed to investigate the effect of biocalcification on compressive strength of soil-cement interlocking block. Method. Soil bacterium, Bacillus pasteurii KCTC 3558, and Effective Microorganisms (EM were added into interlocking block before molding as the replacement of mixing water. The change of compressive strength in interlocking block at 3, 7, 14 and 28 days of incubation was determined. Results. At 28 days, the compressive strength of interlocking block supplemented with B. pasteurii KCTC 3558 and 5% EM were 7.38% and 9.79% significantly higher than control. Calcium carbonate crystals were also observed under scanning electron microscope which suggested that an increased compressive strength of interlocking block was caused by biocalcification. Conclusions. Our results showed that microbiologically induced calcite precipitation could help increasing the compressive strength of soil-cement interlocking block.

  20. Relation between Modulus of Elasticity and Compressive Strength of Ultrahigh-Strength Mortar with Mixed Silicon Carbide as Fine Aggregate

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Ultrahigh-strength mortar mixed surface-oxidized silicon carbide as a fine aggregate was prepared by means of press-casting followed by curing in an autoclave. The relation between modulus of elasticity up to 111 GPa and compressive strength up to 360 MPa of mortar mixed silicon carbide was discussed and it was revealed that the contributions of the aggregate hardness and of the interfacial strength between the aggregate and the cement paste on the elasticity of mortar were imporant.

  1. Microstructure and compression strength of novel TRIP-steel/Mg-PSZ composites

    Science.gov (United States)

    Biermann, H.; Aneziris, C. G.; Kolbe, A.; Martin, U.; Müller, A.; Schärfl, W.; Herrmann, M.

    2010-07-01

    A novel steel-based composite material, composed of metastable austenitic stainless steel as matrix and up to 15 % zirconia as reinforcement, is processed by two powder metallurgy routes. The matrix exhibits the so-called TRIP-effect (TRIP: TRansformation-Induced Plasticity) and shows a deformation-induced formation of martensite. Compression tests of rod samples processed by cold isostatic pressing show increased strength compared to the non-reinforced steel matrix up to 20 % strain. Three-point bending tests show, however, reduced ductility for high zirconia contents. Filigree honeycomb structures were produced by a novel extrusion technique with extraordinary high values of specific energy absorption.

  2. A comparison study on the flexural strength and compressive strength of four resin-modified luting glass ionomer cements.

    Science.gov (United States)

    Li, Yuan; Lin, Hong; Zheng, Gang; Zhang, Xuehui; Xu, Yongxiang

    2015-01-01

    The purpose of this study is to compare the differences in flexural strength and compressive strength between four resin-modified luting glass ionomer cements that are commonly used in clinics. Furthermore, this study investigates the influence of curing mode on the flexural strength and compressive strength of dual-cured resin-modified glass ionomer cements. Initially, flexural strength and compressive strength test specimens were prepared for RL, NR, GCP, and GCC. The RL group and NR group were cured by the light-curing mode and chemical-curing mode. Five specimens were prepared for each test group, and the flexural strength and compressive strength of each were measured. Data were analyzed by one-way ANOVA with SPSS 13.0. Furthermore, the fracture morphology of the flexural specimens was observed by SEM. The result of the mean flexural strength of each group is as follows: the NR light-cured group > NR chemically-cured group > GCP > RL light-cured group > GCC > RL chemically-cured group. More specifically, the flexural strength of the NR light-cured group ((42.903±4.242) MPa) is significantly higher (P NR chemically-cured group > NR light-cured group > GCC > RL light-cured group > RL chemically-cured group. Although the compressive strengths of the NR and GCP groups are higher than those of the GCC and RL groups, there are no significant differences (P>0.05) between NR and GCP, and no significant differences between GCC and RL. Furthermore, there are no significant differences (P>0.05) between the two curing modes on NR and RL. From the present study, it can be concluded that NR has superior flexural strength and compressive strength compared to the other three materials. Additionally, the curing mode can affect the flexural strength of dual-cured RMGIC because with the light-curing mode, the flexural strength is higher than with the chemical-curing mode. Therefore, light curing is an essential procedure when using dual-cured RMGIC in clinics.

  3. [Effects of silicon carbide on the cure depth, hardness and compressive strength of composite resin].

    Science.gov (United States)

    Wang, Ke; Lin, Yi'na; Liu, Xiaoqing

    2009-08-01

    The hardness, compressive strength and cure depth are important indices of the composite resin. This investigation was made with regard to the effects of silicon carbide on the cure depth, hardness and compressive strength of the light-curing composite resin. Different amounts of silicon carbide were added to the light-curing composite resin, which accounted for 0 wt%, 1 wt%, 0.6 wt%, 0.3 wt%, 0.1 wt%, 0.05 wt% and 0.005 wt% of the composite resin, respectively. The hardness, compressive strength and cure depth of the six afore-mentioned groups of composite resin were measured by the vernier caliper, the vickers hardness tester and the tensile strength of machine, respectively. The results showed that silicon carbide improved the hardness and compressive strength of the light-curing composite resin,when the concentration was 0.05 wt%. And the cure depth was close to that of control.

  4. Strength and failure behaviour of spark plasma sintered steel-zirconia composites under compressive Loading

    Energy Technology Data Exchange (ETDEWEB)

    Krueger, L.; Decker, S.; Ehinger, D. [Institute of Materials Engineering, TU Bergakademie Freiberg (Germany); Ohser-Wiedemann, R.; Martin, S.; Martin, U.; Seifert, H.J. [Institute of Materials Science, TU Bergakademie Freiberg (Germany)

    2011-09-15

    Several composites, consisting of a metastable austenitic steel matrix and varying amounts of MgO partially stabilized zirconia particles (Mg-PSZ), were produced through spark plasma sintering (SPS). Compression tests were carried out at room temperature in a wide range of strain rate (4 . 10{sup -4} s{sup -1}, 2 . 10{sup -3} s{sup -1}, 10{sup -1} s{sup -1}, 1 s{sup -1}, 10{sup 2} s{sup -1}). In conjunction with subsequent microstructural investigations, the mechanical material behaviour was clarified. All composites showed a good ductility and a high strength. The strength increased with an increase of the ceramic content and with higher strain rates. Both, the martensitic transformation of the steel matrix and of the ceramic particles, could be proved at all strain rates. In this study no significant influence of the strain rate on the amount of transformed ceramic could be detected while the steel matrix showed less {alpha}'-martensite after compression at rising strain rates. Local material failure occurred around 0.3 true compressive strain depending on the applied strain rate and the amount of the Mg-PSZ powder. The main reason for the damage is the relatively weak ceramic-ceramic interface within the ceramic clusters. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Effect of Specimen Shape and Size on the Compressive Strength of Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Sudin M.A.S.

    2014-03-01

    Full Text Available Lightweight concrete, in the form of foamed concrete, is a versatile material that primarily consists of a cement based mortar, mixed with at least 20% volume of air. Its dry density is typically below 1600 kg/m3 with a maximum compressive strength of 15MPa. The ASTM standard provision specifies a correction factor for concrete strength of between 14 and 42Mpa, in order to compensate for a reduced strength, when the aspect height-to-diameter ratio of a specimen is less than 2.0. However, the CEB-FIP provision specifically mentions a ratio of 150mm dia. × 300mm cylinder strength to 150 mm cube strength; though, both provision requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength to lightweight concrete (in this case, foamed concrete. The focus of this work is to study the effect of specimen size and shape on the axial compressive strength of concrete. Specimens of various sizes and shapes were cast with square and circular cross-sections i.e., cubes, prisms, and cylinders. Their compression strength behaviours at 7 and 28 days were investigated. The results indicate that, as the CEB-FIP provision specified, even for foamed concrete, 100mm cubes (l/d = 1.0 produce a comparable compressive strength with 100mm dia. × 200mm cylinders (l/d = 2.0.

  6. Aggregate effects on γ-ray shielding characteristics and compressive strength on concrete

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jeong Hwan; Choi, Soo Seok [Jeju National University, Jeju (Korea, Republic of); Mun, Young Bun; Lee, Jae Hyung; Choi, Hyun Kook [Sungshin Cement Co., Ltd, Sejong (Korea, Republic of)

    2016-12-15

    We observed the γ-ray shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of 0.371 cm-1 from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a γ-ray of {sup 137}Cs, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of 3,175 kg·m{sup -3}. Although the unit weight of the concrete with OSS and OSG was 3,052 kg·m{sup -3}, which was lower than the maximum unit weight condition by 123 kg·m{sup -3}, its attenuation coefficient was improved by 0.012 cm-1. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced γ-ray shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing.

  7. Effect of In-Situ Curing on Compressive Strength of Reactive Powder Concrete

    OpenAIRE

    Bali Ika; Kushartomo Widodo; Jonathan

    2016-01-01

    A development of Reactive Powder Concrete (RPC) currently is the use of quartz powder as a stabilizing agent with the content to cement ratio of 30% and steam curing method in an autoclave temperature of 250ºC which produced a high compressive strength of 180 MPa. That RPC can be generated due to one reason for using the technique of steam curing in an autoclave in the laboratory. This study proposes in-situ curing method in order the curing can be applied in the field and with a reasonable c...

  8. Compressive strength of fiber reinforced composite materials. [composed of boron and epoxy

    Science.gov (United States)

    Davis, J. G., Jr.

    1974-01-01

    Results of an experimental and analytical investigation of the compressive strength of unidirectional boron-epoxy composite material are presented. Observation of fiber coordinates in a boron-epoxy composite indicates that the fibers contain initial curvature. Combined axial compression and torsion tests were conducted on boron-epoxy tubes, and it was shown that the shear modulus is a function of axial compressive stress. An analytical model which includes initial curvature in the fibers and permits an estimate of the effect of curvature on compressive strength is proposed. Two modes of failure which may result from the application of axial compressive stress are analyzed, delamination and shear instability. Based on tests and analysis, failure of boron-epoxy under axial compressive load is due to shear instability.

  9. Comparative study on compressive strength of Self cured SCC and Normally cured SCC

    Directory of Open Access Journals (Sweden)

    Ms. Akanksha A. Patil

    2014-11-01

    Full Text Available Curing is the process of maintaining proper moisture content particularly within 28 days to promote optimum cement hydration immediately after placement. Self-compacting concrete is made up of admixture i.e. superplasticizer. In recent years, self-compacting concrete (SCC has gained wide use for placement in congested reinforced concrete structures with difficult casting conditions. Also various curing methods are adopted in the construction industry especially for vertical structures, inaccessible areas s.a. high rise buildings, water scarce areas etc. In such structures conventional curing is not practically possible in most of the cases. But we need efficient curing which improves the strength and durability of concrete. In the present work, comparison of compressive strength of normally cured SCC and SCC cured with self curing material i.e. wax based, white pigmented, membrane forming concrete curing compound has been done. This study is investigating that weather the use of self curing compound is economical or not in remote areas of water without compromising with the compressive strength of concrete.

  10. Effect of luting media on the compressive strengths of two types of all-ceramic crown.

    Science.gov (United States)

    McCormick, J T; Rowland, W; Shillingburg, H T; Duncanson, M G

    1993-06-01

    This study evaluated the effect of selected luting media on the compressive strength of two types of all-ceramic crown. Tooth preparation was standardized; each preparation had a shoulder width of approximately 1.2 mm, and all internal preparation angles were rounded. Hi-Ceram and Dicor all-ceramic crowns were fabricated and cemented into the preparations with zinc phosphate, glass-ionomer, or composite resin cement. Coronal compressive fracture strengths were determined, using a set of unrestored teeth as a control. There were no statistically significant differences among the mean compressive strengths of the three luting media, and there was no statistically significant difference between the mean compressive strength of Dicor and that of the natural tooth control.

  11. Compressive Strength, Chloride Permeability, and Freeze-Thaw Resistance of MWNT Concretes under Different Chemical Treatments

    Directory of Open Access Journals (Sweden)

    Xingang Wang

    2014-01-01

    Full Text Available This study investigated compressive strength, chloride penetration, and freeze-thaw resistance of multiwalled carbon nanotube (MWNT concrete. More than 100 cylindrical specimens were used to assess test variables during sensitivity observations, including water-cement ratios (0.75, 0.5, and 0.4 and exposure to chemical agents (including gum arabic, propanol, ethanol, sodium polyacrylate, methylcellulose, sodium dodecyl sulfate, and silane. To determine the adequate sonication time for MWNT dispersal in water, the compressive strengths of MWNT concrete cylinders were measured after sonication times ranging from 2 to 24 minutes. The results demonstrated that the addition of MWNT can increase the compressive strength of concrete by up to 108%. However, without chemical treatment, MWNT concretes tend to have poor freeze-thaw resistance. Among the different chemical treatments, MWNT concrete treated with sodium polyacrylate has the best compressive strength, chloride resistance, and freeze-thaw durability.

  12. Compression strength of a fibre composite main spar in a wind turbine blade

    DEFF Research Database (Denmark)

    Jensen, Find Mølholt

    2003-01-01

    In this report the strength of a wind turbine blade is found and compared with a full-scale test, made in the same project. Especially the postbuckling behaviour of the compression flange is studied. Different compressive failure mechanisms are discussedand the limitations in using the Finite...

  13. Compression strength of a fibre composite main spar in a wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Moelholt Jensen, F.

    2003-06-01

    In this report the strength of a wind turbine blade is found and compared with a full-scale test, made in the same project. Especially the post buckling behaviour of the compression flange is studied. Different compressive failure mechanisms are discussed and the limitations in using the Finite Element Method. A suggestion to the further work is made. (au)

  14. The influence of biocalcification on soil-cement interlocking block compressive strength

    OpenAIRE

    Yoosathaporn, S.; Tiangburanatham, P.; Pathom-aree, W.

    2015-01-01

    Description of the subject. Soil-cement interlocking block is used as the building block for many civil structures in Thailand. The addition of many alternative materials into interlocking block in order to improve compressive strength has been reported. However, there is currently no report on the influence of application of biocalcification or microbiologically induced calcite precipitation (MICP) on interlocking block compressive strength. Objectives. This study aimed to investigate the ef...

  15. Relationship between pore structure and compressive strength of concrete: Experiments and statistical modeling

    Indian Academy of Sciences (India)

    J BU; Z TIAN

    2016-03-01

    Properties of concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the pore structure-compressive strength relationship in concrete. Several concrete mixtures with different pore structures are proportioned and subjected to static compressive tests. The pore structure features such as porosity, pore size distribution are extracted using mercury intrusion porosimetry technique. A statistical model is developed to relate thecompressive strength to relevant pore structure features.

  16. The Influence of Mineral Admixtures on Bending Strength of Mortar on the Premise of Equal Compressive Strength

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; YAN Peiyu; FENG Jianwen

    2012-01-01

    The influence of mineral admixtures on bending strength of mortar on the premise of equal compressive strength was investigated.Three mineral admixtures (fly ash,ground granulated blast-furnace slag and steel slag) were used.The adding amount of mineral admixture in this study ranges from 22.5% to 60%,and the water-to-binder ratio ranges from 0.34 to 0.50.With equal compressive strength,different mortars can be arranged in such a descending order with their bending strength:cement-fly ash mortar,cement mortar,cement-GGBS mortar,and cement-steel slag mortar.With the same compressive strength,the higher the steel slag content and water-to-binder ratio,the lower the bending strength of mortars.However,the effect of mineral mixture content and water-to-binder ratio on the bending strength of cement-fly ash mortar and cement-GGBS mortar is far inconspicuous.

  17. Analysis of the Optimum Usage of Slag for the Compressive Strength of Concrete.

    Science.gov (United States)

    Lee, Han-Seung; Wang, Xiao-Yong; Zhang, Li-Na; Koh, Kyung-Taek

    2015-03-18

    Ground granulated blast furnace slag is widely used as a mineral admixture to replace partial Portland cement in the concrete industry. As the amount of slag increases, the late-age compressive strength of concrete mixtures increases. However, after an optimum point, any further increase in slag does not improve the late-age compressive strength. This optimum replacement ratio of slag is a crucial factor for its efficient use in the concrete industry. This paper proposes a numerical procedure to analyze the optimum usage of slag for the compressive strength of concrete. This numerical procedure starts with a blended hydration model that simulates cement hydration, slag reaction, and interactions between cement hydration and slag reaction. The amount of calcium silicate hydrate (CSH) is calculated considering the contributions from cement hydration and slag reaction. Then, by using the CSH contents, the compressive strength of the slag-blended concrete is evaluated. Finally, based on the parameter analysis of the compressive strength development of concrete with different slag inclusions, the optimum usage of slag in concrete mixtures is determined to be approximately 40% of the total binder content. The proposed model is verified through experimental results of the compressive strength of slag-blended concrete with different water-to-binder ratios and different slag inclusions.

  18. Identification of Bacteria and the Effect on Compressive Strength of Concrete

    Directory of Open Access Journals (Sweden)

    Anneza L. H.

    2016-01-01

    Full Text Available This paper presents the species of bacteria used in this study as well as the effect of the bacteria on compressive strength of bioconcrete. Bioconcrete is not only more environmentally friendly but it is easy to procure. The objective of this research is to identify the ureolytic bacteria and sulphate reduction bacteria that have been isolated and further use the bacteria in concrete to determine the effect of bacteria on compressive strength. Identification of bacteria is conducted through Polymerase chain reaction (PCR method and DNA sequencing. The DNA of the bacteria was run through BLAST algorithm to determine the bacterial species.The bacteria were added into the concrete mix as a partial replacement of water. 3% of water is replaced by ureolytic bacteria and 5% of water is replaced by sulphate reduction bacteria. After running BLAST algorithm the bacteria were identified as Enterococcus faecalis (ureolytic bacteria and Bacillus sp (sulphate reduction bacteria. The result of the compressive strength for control is 36.0 Mpa. Partial replacement of 3% water by ureolytic bacteria has strength of 38.2Mpa while partial replacement of 5% of water by sulphate reduction bacteria has strength of 42.5Mpa. The significant increase of compressive strength with the addition of bacteria shows that bacteria play a significant role in the improvement of compressive strength.

  19. Unfired clay bricks – moisture properties and compressive strength

    DEFF Research Database (Denmark)

    Hansen, E.J. de Place; Hansen, Kurt Kielsgaard

    2002-01-01

    Apparatus, methods and test results from an experimental investigation of (1) the properties for moisture performance of the materials, including water vapour sorption and water vapour transmission, (2) humidity buffering of the indoor climate by an absorbent material, and (3) the compressive str...

  20. Derivation of the Bi-axial Bending, Compression and Shear Strengths of Timber Beams

    NARCIS (Netherlands)

    Van der Put, T.A.C.M.

    2012-01-01

    The derivation is given of the combined bi-axial bending, compression and shear strength of timber beams. As for other materials the elastic–full plastic limit design approach applies, which is known to precisely explain and predict uniaxial bending strength behaviour. The derivation is based on cho

  1. Multiple Regression Analysis of Unconfined Compression Strength of Mine Tailings Matrices

    Directory of Open Access Journals (Sweden)

    Mahmood Ali A.

    2017-01-01

    Full Text Available As part of a novel approach of sustainable development of mine tailings, experimental and numerical analysis is carried out on newly formulated tailings matrices. Several physical characteristic tests are carried out including the unconfined compression strength test to ascertain the integrity of these matrices when subjected to loading. The current paper attempts a multiple regression analysis of the unconfined compressive strength test results of these matrices to investigate the most pertinent factors affecting their strength. Results of this analysis showed that the suggested equation is reasonably applicable to the range of binder combinations used.

  2. Effect of raw material ratios on the compressive strength of magnesium potassium phosphate chemically bonded ceramics.

    Science.gov (United States)

    Wang, Ai-juan; Yuan, Zhi-long; Zhang, Jiao; Liu, Lin-tao; Li, Jun-ming; Liu, Zheng

    2013-12-01

    The compressive strength of magnesium potassium phosphate chemically bonded ceramics is important in biomedical field. In this work, the compressive strength of magnesium potassium phosphate chemically bonded ceramics was investigated with different liquid-to-solid and MgO-to-KH2PO4 ratios. X-ray diffractometer was applied to characterize its phase composition. The microstructure was imaged using a scanning electron microscope. The results showed that the compressive strength of the chemically bonded ceramics increased with the decrease of liquid-to-solid ratio due to the change of the packing density and the crystallinity of hydrated product. However, with the increase of MgO-to-KH2PO4 weight ratio, its compressive strength increased firstly and then decreased. The low compressive strength in lower MgO-to-KH2PO4 ratio might be explained by the existence of the weak phase KH2PO4. However, the low value of compressive strength with the higher MgO-to-KH2PO4 ratio might be caused by lack of the joined phase in the hydrated product. Besides, it has been found that the microstructures were different in these two cases by the scanning electron microscope. Colloidal structure appeared for the samples with lower liquid-to-solid and higher MgO-to-KH2PO4 ratios possibly because of the existence of amorphous hydrated products. The optimization of both liquid-to-solid and MgO-to-KH2PO4 ratios was important to improve the compressive strength of magnesium potassium phosphate chemically bonded ceramics.

  3. Experimental study on the compressive strength of grouted concrete block masonry based on nondestructive detection methods

    Institute of Scientific and Technical Information of China (English)

    JIANG Hong-bin; LI Long-fei

    2009-01-01

    Existing nondestructive detection methods were adopted to test the compressive strength of grouted concrete block masonry, i.e. the rebound method, pulling-out method and core drilling method were employed to test the strength of block, mortar and grouted concrete, respectively. The suitability of these methods for the testing of strength of grouted concrete block masonry was discussed, and the comprehensive strength of block masonry was appraised by combining existing nondestructive or micro-destructive detection methods. The nondestructive detection test on 25 grouted concrete block masonry specimens was carried out. Experimental results show that these methods mentioned above are applicable for the strength detection of grouted concrete block masonry. Moreover, the formulas of compressive strength, detection methods and proposals are given as well.

  4. Achievement of Early Compressive Strength in Concrete Using Sporosarcina pasteurii Bacteria as an Admixture

    Directory of Open Access Journals (Sweden)

    Rakesh Chidara

    2014-01-01

    Full Text Available Often it is observed, attainment of early compressive strength in concrete is a challenge. Researchers have tried various admixtures to achieve the objective. This work addresses the issue of achieving early compressive strength in concrete using a bacterium called Sporosarcina pasteurii. The bacterium is characterised with the ability to precipitate calcium carbonate in the presence of any carbonate source and is known for its resistive capacity in extreme temperature and pressure zones. To establish the objective of gain in early strength around 192 concrete cubes were tested at 3, 7, 14, and 28 days and the results compared with controlled concrete. The bacterium was used in combination of chemicals and the dosage proportions were altered to achieve the desired M20 compressive strength at 28 days.

  5. The estimation of compressive strength of normal and recycled aggregate concrete

    Directory of Open Access Journals (Sweden)

    Janković Ksenija

    2011-01-01

    Full Text Available Estimation of concrete strength is an important issue in ready-mixed concrete industry, especially, in proportioning new mixtures and for the quality assurance of the concrete produced. In this article, on the basis of the existing experimental data of compressive strength of normal and recycled aggregate concrete and equation for compressive strength calculating given in Technical regulation are compared. The accuracies of prediction by experimental data obtained in laboratory as well as by EN 1992-1-1, ACI 209 and SRPS U.M1.048 are compared on the basis of the coefficient of determination. The determination of the compressive strengths by the equation described here relies on determination of type of cement and age of concrete with the constant curing temperature.

  6. Non-Uniform Compressive Strength of Debonded Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian; Simonsen, Bo Cerup

    2005-01-01

    This article describes the development, validation and application of a FEM based numerical model for prediction of residual strength of damaged sandwich panels. The core of the theoretical method is a newly developed procedure for prediction of the propagation of a face-core debond. As demonstra......This article describes the development, validation and application of a FEM based numerical model for prediction of residual strength of damaged sandwich panels. The core of the theoretical method is a newly developed procedure for prediction of the propagation of a face-core debond.......(2005)., shows that the model is indeed able to predict the failure modes and the residual strength of damaged panels with accuracy sufficient for practical applications. This opens up for a number of important engineering applications, for example risk-based inspection and repair schemes....

  7. Influence of Compression and Shear on the Strength of Composite Laminates with Z-Pinned Reinforcement

    Science.gov (United States)

    O'Brien, T. Kevin; Krueger, Ronald

    2005-01-01

    The influence of compression and shear loads on the strength of composite laminates with z-pins is evaluated parametrically using a 2D Finite Element Code (FLASH). Meshes were generated for three unique combinations of z-pin diameter and density. A laminated plate theory analysis was performed on several layups to determine the bi-axial stresses in the zero degree plies. These stresses, in turn, were used to determine the magnitude of the relative load steps prescribed in the FLASH analyses. Results indicated that increasing pin density was more detrimental to in-plane compression strength than increasing pin diameter. FLASH results for lamina with z-pins were consistent with the closed form results, and FLASH results without z-pins, if the initial fiber waviness due to z-pin insertion was added to the fiber waviness in the material to yield a total misalignment. Addition of 10% shear to the compression loading significantly reduced the lamina strength compared to pure compression loading. Addition of 50% shear to the compression indicated shear yielding rather than kink band formation as the likely failure mode. Two different stiffener reinforced skin configurations with z-pins, one quasi-isotropic and one orthotropic, were also analyzed. Six unique loading cases ranging from pure compression to compression plus 50% shear were analyzed assuming material fiber waviness misalignment angles of 0, 1, and 2 degrees. Compression strength decreased with increased shear loading for both configurations, with the quasi-isotropic configuration yielding lower strengths than the orthotropic configuration.

  8. Lightweight, highly compressible, noncrystalline cellulose capsules.

    Science.gov (United States)

    Carrick, Christopher; Lindström, Stefan B; Larsson, Per Tomas; Wågberg, Lars

    2014-07-08

    We demonstrate how to prepare extraordinarily deformable, gas-filled, spherical capsules from nonmodified cellulose. These capsules have a low nominal density, ranging from 7.6 to 14.2 kg/m(3), and can be deformed elastically to 70% deformation at 50% relative humidity. No compressive strain-at-break could be detected for these dry cellulose capsules, since they did not rupture even when compressed into a disk with pockets of highly compressed air. A quantitative constitutive model for the large deformation compression of these capsules is derived, including their high-frequency mechanical response and their low-frequency force relaxation, where the latter is governed by the gas barrier properties of the dry capsule. Mechanical testing corroborated these models with good accuracy. Force relaxation measurements at a constant compression rendered an estimate for the gas permeability of air through the capsule wall, calculated to 0.4 mL μm/m(2) days kPa at 50% relative humidity. These properties taken together open up a large application area for the capsules, and they could most likely be used for applications in compressible, lightweight materials and also constitute excellent model materials for adsorption and adhesion studies.

  9. High strength, tough alloy steel

    Science.gov (United States)

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  10. Compressive Strength of 2D-C/SiC Composite at High Temperature in Air%2D-C/SiC复合材料在空气中的高温压缩强度研究

    Institute of Scientific and Technical Information of China (English)

    牛学宝; 张程煜; 乔生儒; 韩栋; 李玫

    2011-01-01

    研究了二维碳纤维增强碳化硅基复合材料(2 D-C/SiC)在空气介质中的高温压缩强度.材料采用1K T300碳纤维平纹布经叠层和缝合制成预制体为增强体,经等温化学气相浸渗制备而成.试样表面用化学气相沉积工艺沉积SiC涂层.测试方向为垂直于炭布叠层方向,测试温度为室温,700℃,1100℃和1300℃.使用扫描电子显微镜观察了材料的断口.结果表明:室温~700℃,2D-C/SiC的压缩强度随温度升高逐渐增大,温度高于700℃后,材料的压缩强度缓慢降低.导致2D-C/SiC的压缩强度随温度变化的主要原因为纤维和基体热膨胀系数不同引起的残余应力随温度升高逐渐变小和高温下材料的氧化损伤.%The compressive strength of a two dimensional carbon fiber reinforced silicon carbide composite (2D-C/SiC) at elevated temperature in air was studied. The plain weaved carbon cloth was applied as reinforcement, made of stacked and seamed 1K T300 carbon fiber cloth. The 2D-C/SiC was prepared by isothermal chemical vapor infiltration. The specimens were coated with SiC by chemical vapor deposition. The tests were conducted at room temperature, 700°C , 1100°C and 1300°C respectively, and the loading direction was perpendicular to 2D-C/SiC plane. The fractured surface of the specimens was observed by a scanning electron microscope. The results show that the compressive strength increases gradually with increasing the temperature from room temperature to 700°C , while it decreases gradually when the temperature was above 700°C. The residual stress caused by the mismatch between the thermal expansion coefficients of the fiber and matrix, and the oxidation products play important roles in determining the compressive strength.

  11. Effect of root canal irrigating solutions on the compressive strength of tricalcium silicate cements.

    Science.gov (United States)

    Govindaraju, Lokhasudhan; Neelakantan, Prasanna; Gutmann, James L

    2017-03-01

    The aim of this study was to evaluate the effect of root canal irrigants on the compressive strength of hydraulic tricalcium silicate cements. Specimens (n = 60) of tricalcium silicate materials-Group 1: White ProRoot mineral trioxide aggregate (MTA), Group 2: NeoMTA Plus, Group 3: White MTA Angelus, and Group 4: Biodentine were exposed to one of the solutions (n = 20): Phosphate buffered saline (PBS; control), 3 % NaOCl, or 17 % EDTA for 5 min while being suspended in PBS. Compressive strength values were evaluated after 7 days of storage. The data were statistically analyzed by two-way ANOVA and Tukey's multiple comparison test (P = 0.05). Biodentine (BD) showed significantly higher compressive strength than the other materials (P Biodentine and NeoMTA Plus did not show a significant reduction in compressive strength when exposed to NaOCl. EDTA reduced the compressive strength of the cements tested. Tricalcium silicates were differentially influenced by root canal irrigants. It is essential to understand the composition of these materials prior to clinical use. Traces of irrigants from the root canal wall must be thoroughly removed.

  12. The increase of compressive strength of natural polymer modified concrete with Moringa oleifera

    Science.gov (United States)

    Susilorini, Rr. M. I. Retno; Santosa, Budi; Rejeki, V. G. Sri; Riangsari, M. F. Devita; Hananta, Yan's. Dianaga

    2017-03-01

    Polymer modified concrete is one of some concrete technology innovations to meet the need of strong and durable concrete. Previous research found that Moringa oleifera can be applied as natural polymer modifiers into mortars. Natural polymer modified mortar using Moringa oleifera is proven to increase their compressive strength significantly. In this resesearch, Moringa oleifera seeds have been grinded and added into concrete mix for natural polymer modified concrete, based on the optimum composition of previous research. The research investigated the increase of compressive strength of polymer modified concrete with Moringa oleifera as natural polymer modifiers. There were 3 compositions of natural polymer modified concrete with Moringa oleifera referred to previous research optimum compositions. Several cylinder of 10 cm x 20 cm specimens were produced and tested for compressive strength at age 7, 14, and, 28 days. The research meets conclusions: (1) Natural polymer modified concrete with Moringa oleifera, with and without skin, has higher compressive strength compared to natural polymer modified mortar with Moringa oleifera and also control specimens; (2) Natural polymer modified concrete with Moringa oleifera without skin is achieved by specimens contains Moringa oleifera that is 0.2% of cement weight; and (3) The compressive strength increase of natural polymer modified concrete with Moringa oleifera without skin is about 168.11-221.29% compared to control specimens

  13. Evaluation of compressive strength of hydraulic silicate-based root-end filling materials.

    Science.gov (United States)

    Walsh, Ryan M; Woodmansey, Karl F; Glickman, Gerald N; He, Jianing

    2014-07-01

    Hydraulic silicate cements such as mineral trioxide aggregate (MTA) have many clinical advantages. Newer hydraulic silicate materials have been developed that improve on the limitations of mineral trioxide aggregate such as the long setting time and difficult handling characteristics. The purpose of this study was to examine the effect of saline and fetal bovine serum (FBS) on the setting and compressive strength of the following hydraulic silicate cements: ProRoot MTA (white WMTA; Dentsply International, Tulsa Dental Specialties, Johnson City, TN), EndoSequence Root Repair Material (Brasseler USA, Savannah, GA), MTA Plus (MTAP; Avalon Biomed Inc, Bradenton, FL), and QuickSet (QS; Avalon Biomed Inc, Bradenton, FL). Samples of root-end filling materials were compacted into polyethylene molds. Samples were exposed to FBS or saline for 7 days. A universal testing machine was used to determine the compressive strengths. QS had significantly lower compressive strength than all other materials (P materials, other than QS, have compressive strength similar to MTA. Within the limits of this study, premixed materials and those mixed with antiwashout gel maintain their compressive strength when exposed to biological fluids. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  14. optimisation of compressive strength of periwinkle shell aggregate ...

    African Journals Online (AJOL)

    user

    2017-01-01

    Jan 1, 2017 ... The periwinkle shells used for this study were obtained from heaps at Okrika .... Nigerian Building and Road Research Institute, Lagos,. Technical Paper 2 ... Strength of Concrete: A Case Study for Shear Modulus of. Rice Husk Ash ... 30 REM zi, z2,z3, z4, xl, x2, x3, x4, yzuax, yout, yin. 40 REM Begin Main ...

  15. Axial dynamic tensile strength of concrete under static lateral compression

    NARCIS (Netherlands)

    Weerheijm, J.

    2006-01-01

    The rate effect on concrete tensile strength can be modeled by the description of crack extension in a fictitious fracture plane [1,2].The plane represents the initial, internal damage and the geometry of the final fracture plane. In the paper, the same approach is applied to model the failure envel

  16. marine water effect on compressive strength of concrete

    African Journals Online (AJOL)

    hp

    Concrete cubes cast and cured with seawater were observed to have a higher strength at 28 ... However, in the case of reinforced concrete, it is recommended that reinforcement be prevented from corrosion by ... Cracking facilitate the entry of de-icing salt solution that may .... From Table 2, it can be seen that the value of the.

  17. Structural mechanism and effect of hole compressibility on mechanical strength of MFLB

    Institute of Scientific and Technical Information of China (English)

    Yan MA; Alun

    2008-01-01

    We have studied the structural mechanism of micron flaky wood fiber light density board (MFLB), of which voids are an important structural characteristic. A new parameter called hole compressibility (η) was added to study the characteristics of MFLB further, in order to produce various levels of hole compressibility. A set of hot pressures was applied, and uniform parts at cross-sections of MFLB were selected to study the effects of hole com-pressibility on the modulus of elasticity (MOE) and modulus of rupture (MOR) of MFLB by microscopic analyses. The results showed that MFLB (0.3 g/cm in density) processed at various hot pressures (from 1.6 to 2.2 MPa) all meet the norms of the Japan Light Parti-cleboard Industrial Standard JISA 5908, where η≤ 0 ran-ging from -0.0487 to -0.068. The critical value of hole compressibility at which the strength began to decrease was also obtained. We compared the void distribution, size and shape at different void contents and hole com-pressibility and discussed the effects of hole compressibil-ity on MOE and MOR of MFLB as well. To a certain density of raw material and micro-fiber of a certain thick-ness, the strength of MFLB can be decreased with an increase in hole compressibility. When the hole compres-sibility of MLFB exceeds a certain critical value, loading at a lower level will decrease MOR and MOE of MFLB considerably.

  18. Introducing Mg-4Zn-3Gd-1Ca/ZnO nanocomposite with compressive strengths matching/exceeding that of mild steel

    Science.gov (United States)

    Chen, Y.; Tekumalla, S.; Guo, Y. B.; Gupta, M.

    2016-08-01

    This work introduces Mg-4Zn-3Gd-1Ca/2ZnO (wt.%) nanocomposite fabricated using the technique of disintegrated melt deposition and extrusion. Addition of ZnO nanoparticles enhanced the compressive strengths of alloy by ~100 MPa. Nanocomposite samples display high strength and good ductility: 0.2% compressive yield stress of 355 MPa, ultimate compressive stress of 703 MPa, and compressive failure strain of 10.6%. The significant enhancement of compressive yield stress is mainly attributed to the grain refinement by adding nanoparticles. The strength levels exceed that of commercial magnesium alloys (i.e. WE43, WE54, ZK60, and ME21) and mild steels (i.e. S275 and S355), making Mg-4Zn-3Gd-1Ca/2ZnO a very promising material for multiple engineering and biomedical applications.

  19. Introducing Mg-4Zn-3Gd-1Ca/ZnO nanocomposite with compressive strengths matching/exceeding that of mild steel.

    Science.gov (United States)

    Chen, Y; Tekumalla, S; Guo, Y B; Gupta, M

    2016-08-30

    This work introduces Mg-4Zn-3Gd-1Ca/2ZnO (wt.%) nanocomposite fabricated using the technique of disintegrated melt deposition and extrusion. Addition of ZnO nanoparticles enhanced the compressive strengths of alloy by ~100 MPa. Nanocomposite samples display high strength and good ductility: 0.2% compressive yield stress of 355 MPa, ultimate compressive stress of 703 MPa, and compressive failure strain of 10.6%. The significant enhancement of compressive yield stress is mainly attributed to the grain refinement by adding nanoparticles. The strength levels exceed that of commercial magnesium alloys (i.e. WE43, WE54, ZK60, and ME21) and mild steels (i.e. S275 and S355), making Mg-4Zn-3Gd-1Ca/2ZnO a very promising material for multiple engineering and biomedical applications.

  20. In situ strength of coal bed based on the size effect study on the uniaxial compressive strength

    Institute of Scientific and Technical Information of China (English)

    Gonzatti C.; Zorzi L.; Agostini I.M.; Fiorentini J.A.; Viero A.P.; Philipp R.P.

    2014-01-01

    In the early 1990s, the Foundation for Science and Technology of Rio Grande do Sul State (CIENTEC) developed a pioneering study in Brazil, related to the simultaneous mining of multiple coal seams. One of the activities included detailed studies on the geomechanical characterization of materials present in the Irapua coal seam, under exploitation in the A-Sangao Mine, located near the city of Criciuma-SC, within the South-Catarinense coalfield. The goal of the laboratory tests was to define the behavior of the uniaxial compressive strength of the Irapua coal seam and establish a first approximation for the in situ strength value of this coal seam, since existing knowledge is solely based on practical mining experience over the years. Large samples of the coal seam were collected, using special techniques to maintain the integrity of the material, and a set of 56 uniaxial compression tests in cubic specimens, with side length ranging from 4.5 to 31 cm, were conducted in laboratory. This paper describes the experimen-tal techniques used in the assays, and also presents the uniaxial compression strength results obtained. Moreover, important aspects of this type of study are considered, highlighting the size effect for the carbonaceous bed and the estimation of in situ strength values for the Irapua coal seam.

  1. Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete

    Directory of Open Access Journals (Sweden)

    Olusola K. O.

    2010-01-01

    Full Text Available This study investigates the effect of partial replacement of cement with volcanic ash (VA on the compressive strength of laterized concrete. A total of 192 cubes of 150mm dimensions were cast and cured in water for 7, 14, 21, and 28 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively, while a control mix of 28-day target strength of 25 N/mm2 was adopted. The results show that the density and compressive strength of concrete decreased with increase in volcanic ash content. The 28-day, density dropped from 2390 kg/m3 to 2285 kg/m3 (i.e. 4.4% loss and the compressive strength from 25.08 N/mm2 to 17.98 N/mm2 (i.e. 28% loss for 0-30% variation of VA content with no laterite introduced. The compressive strength also decreased with increase in laterite content; the strength of the laterized concrete however increases as the curing age progresses.

  2. Predicting of the compressive strength of RCA concrete

    Directory of Open Access Journals (Sweden)

    Jaskulski Roman

    2017-01-01

    Full Text Available The paper presents the results of predicting the strength of 61 concretes made with the use of recycled concrete aggregate (RCA. Five models in the form of first-order polynomials containing two to six variables characterizing the composition of the mixture were formulated for this purpose. Factors for unknowns were selected using linear regression in two variants: with and without additional coefficient. For each model, the average absolute error of the concrete strength estimation was determined. Because of the various consequences of underestimation and overestimation of the results, the analysis of models quality was carried out with the distinction of the two cases. The results indicate that the key to improving the quality of models is to take into account the quality of the aggregate expressed by the ACV parameter. Better match results were also obtained for models with more variables and the additional coefficient.

  3. Dynamic compressive and tensile strengths of spark plasma sintered alumina

    Science.gov (United States)

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M. P.; Frage, N.

    2014-06-01

    Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1 km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100-1000 m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr2O3 decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

  4. Effect of lightweight aggregate intrinsic Strength on lightweight concrete compressive strength and modulus of elasticity

    Directory of Open Access Journals (Sweden)

    Videla, C.

    2002-03-01

    Full Text Available The study of Structural Lightweight Concrete (SLC, which is a material generally composed of cement, water and lightweight aggregate, has been mainly focused on developing particular cases. Then, the main objective of this research was to generalise the knowledge of this type of material. Particularly, the effect of replacing conventional coarse aggregate by lightweight aggregate on mechanical properties of concrete was studied. SLC may be conceived as a two -phase material. The first phase, composed of cement, water and siliceous natural sand, is called the "resistant phase", and contributes to the structural strength. The second phase is the lightweight phase, comprised of coarse lightweight aggregate, and it is meant to decrease the concrete density. In this way it would be possible to describe the mechanical behaviour of concrete, based on lightweight aggregate and the cement mortar parameters. The obtained results allow for the proposition of relationships between mechanical properties of SLC (such as compressive strength and modulus of elasticity and the constituent materials properties and amount. At the same time, an easily measured index representing the structural capability of lightweight aggregate is also proposed, this index allows to estimate the potential mechanical properties of concrete which could be obtained by using a particular aggregate.

    El estudio del Hormigón Ligero Estructural (HLE, material compuesto generalmente por cemento, agua y árido ligero, ha estado enfocado principalmente al desarrollo de casos particulares. Por lo anterior, el objetivo principal de esta investigación fue generalizar el conocimiento sobre este material. En particular, la meta de este trabajo fue estudiar el efecto que tiene el reemplazo de árido convencional por un árido ligero, en las propiedades mecánicas del hormigón. El modelo aplicado conceptualiza al HLE como un material de dos fases, una denominada "soportante", constituida

  5. Alumina/Polyimide Composite Porous Nanosolid:Dielectric Characteristics and Compressive Strength

    Institute of Scientific and Technical Information of China (English)

    LUAN Chun-hong; GENG Yu-jing; YU Qin-qin; CAO Li-li; LIAN Gang; CUI De-liang

    2012-01-01

    Al2O3 porous nanosolid was prepared via solvothermal hot-press(SHP) method.The dielectric constant of Al2O3 porous nanosolid is as low as 2.34,while its compressive strength is very poor.In order to improve the compressive strength and maitain low dielectric constant,polyimidc was introduced to prepare Al2O3/polyimide composite porous nanosolid.Compared to Al2O3 porous nanosolid,Al2O3/polyimide composite porous nanosolid possesses much higher compressive strength,which reaches its saturation value when the mass loading of polyimide is 7.75%.In addition,the in situ Fourier transformation infrared(FTIR) monitoring result reveals that Al2O3/polyimide composite porous nanosolid is stable up to 400 ℃.

  6. A Study of Compressive Strength Characteristics of Laterite Sand Hollow Blocks

    Directory of Open Access Journals (Sweden)

    Abiodun Olanipekun

    2007-01-01

    Full Text Available This paper presents the results of experimental investigations carried out on partial replacement of sand with laterite as it affects the compressive strength of sandcrete hollow blocks. Two mix proportions (1:6 and 1:8 were used with laterite content varying between 0 and 50% at 10% intervals. Hand and machine compaction methods were used. Curing was done by sprinkling water on the specimens. The results showed that for each mix proportion and compaction method, the compressive strength decreases with increase in laterite content. Machine compacted hollow sandcrete blocks made from mix ratio 1:6 and with up to 10% laterite content is found suitable and hence recommended for building construction having attained a 28-day compressive strength of 2.07N/mm2 as required by the Nigerian Standards.

  7. Characterization of compressive and short beam shear strength of bamboo opened cell foam core sandwich composites

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Paryanto Dwi, E-mail: paryanto-ds@yahoo.com; Sugiman,; Saputra, Yudhi [Department of Mechanical Engineering, Faculty of Engineering, University of Mataram, Mataram, West Nusa Tenggara (Indonesia)

    2016-03-29

    The paper presents the compressive and the short beam shear strength of a sandwich composite with opened cell foam made of bamboo fiber as the core and plywood as the skins. The core thickness was varied from 10 mm to 40 mm keeping the volume fraction of fiber constant. Several test s were carried out including the core density, flatwise compressive and the short beam shear testing in three point bending. The results show that the density of bamboo opened cell foam is comparable with commercial plastic foam, such as polyurethane foam. The compressive strength tends to increase linearly with increasing the core thickness. The short beam shear failure load of the sandwich composite increases with the increase of core thickness, however on the contrary, the short beam shear strength which tends to sharply decrease from the thickness of 10 mm to 30 mm and then becomes flat.

  8. Characterization of compressive and short beam shear strength of bamboo opened cell foam core sandwich composites

    Science.gov (United States)

    Setyawan, Paryanto Dwi; Sugiman, Saputra, Yudhi

    2016-03-01

    The paper presents the compressive and the short beam shear strength of a sandwich composite with opened cell foam made of bamboo fiber as the core and plywood as the skins. The core thickness was varied from 10 mm to 40 mm keeping the volume fraction of fiber constant. Several test s were carried out including the core density, flatwise compressive and the short beam shear testing in three point bending. The results show that the density of bamboo opened cell foam is comparable with commercial plastic foam, such as polyurethane foam. The compressive strength tends to increase linearly with increasing the core thickness. The short beam shear failure load of the sandwich composite increases with the increase of core thickness, however on the contrary, the short beam shear strength which tends to sharply decrease from the thickness of 10 mm to 30 mm and then becomes flat.

  9. High SNR Consistent Compressive Sensing

    OpenAIRE

    Kallummil, Sreejith; Kalyani, Sheetal

    2017-01-01

    High signal to noise ratio (SNR) consistency of model selection criteria in linear regression models has attracted a lot of attention recently. However, most of the existing literature on high SNR consistency deals with model order selection. Further, the limited literature available on the high SNR consistency of subset selection procedures (SSPs) is applicable to linear regression with full rank measurement matrices only. Hence, the performance of SSPs used in underdetermined linear models ...

  10. Determination of Uniaxial Compressive Strength of Ankara Agglomerate Considering Fractal Geometry of Blocks

    Science.gov (United States)

    Coskun, Aycan; Sonmez, Harun; Ercin Kasapoglu, K.; Ozge Dinc, S.; Celal Tunusluoglu, M.

    2010-05-01

    The uniaxial compressive strength (UCS) of rock material is a crucial parameter to be used for design stages of slopes, tunnels and foundations to be constructed in/on geological medium. However, preparation of high quality cores from geological mixtures or fragmented rocks such as melanges, fault rocks, coarse pyroclastic rocks, breccias and sheared serpentinites is often extremely difficult. According to the studies performed in literature, this type of geological materials may be grouped as welded and unwelded birmocks. Success of preparation of core samples from welded bimrocks is slightly better than unwelded ones. Therefore, some studies performed on the welded bimrocks to understand the mechanical behavior of geological mixture materials composed of stronger and weaker components (Gokceoglu, 2002; Sonmez et al., 2004; Sonmez et al., 2006; Kahraman, et al., 2008). The overall strength of bimrocks are generally depends on strength contrast between blocks and matrix; types and strength of matrix; type, size, strength, shape and orientation of blocks and volumetric block proportion. In previously proposed prediction models, while UCS of unwelded bimrocks may be determined by decreasing the UCS of matrix considering the volumetric block proportion, the welded ones can be predicted by considering both UCS of matrix and blocks together (Lindquist, 1994; Lindquist and Goodman, 1994; Sonmez et al., 2006 and Sonmez et al., 2009). However, there is a few attempts were performed about the effect of blocks shape and orientation on the strength of bimrock (Linqduist, 1994 and Kahraman, et al., 2008). In this study, Ankara agglomerate, which is composed of andesite blocks and surrounded weak tuff matrix, was selected as study material. Image analyses were performed on bottom, top and side faces of cores to identify volumetric block portions. In addition to the image analyses, andesite blocks on bottom, top and side faces were digitized for determination of fractal

  11. Compressive Strength and Water Absorption of Pervious Concrete that Using the Fragments of Ceramics and Roof Tiles

    Directory of Open Access Journals (Sweden)

    Prahara E.

    2014-03-01

    Full Text Available Pervious concrete was introduced in America in 2003, popularized by Dan Brown and used as a rigid pavement in the open parking lot. Rigid pavement using pervious concrete can absorb water in the surface to go straight through the concrete to the ground below.This water flow is one of the benefit of using the pervious concrete. Using of wastes such as broken roof and ceramics tiles are not commonly used in Indonesia. Utilization these kind of wastes is predicted lower the compressive strength of pervious concrete as they are used as a substitute for coarse aggregate.In this research, pervious concrete is made using a mixture of the fragment of ceramics and roof tiles.This research using broken ceramics and roof tiles with a grain size that loose from 38 mm sieve, retained on 19 mm sieve and the coarse aggregate from crushed stone that loose 12.5 mm sieve, retained on 9.5 mm sieve. The water cement ratio is 0.3 and to assist the mixing process, the addition of addictive in pervious concrete is used.The size of coarse aggregate used in the mixture affects the strength of pervious concrete. The larger the size of aggregate, the obtained compressive strength becomes smaller. It also affects the density of pervious concrete. The using of mixture of ceramics and roof tiles only reduce 2 MPa of pervious concrete compressive strength so this mixture can be used as a substitute for coarse aggregate with a maximum portion of 30 %. The high porosity of the specimens causes the reduction of pervious concrete density that affect the compressive strength. This high level of porosity can be seen from the high level of water absorption that exceed the required limit of water infiltration.

  12. Compressive Strength and Water Absorption of Pervious Concrete that Using the Fragments of Ceramics and Roof Tiles

    Science.gov (United States)

    Prahara, E.; Meilani

    2014-03-01

    Pervious concrete was introduced in America in 2003, popularized by Dan Brown and used as a rigid pavement in the open parking lot. Rigid pavement using pervious concrete can absorb water in the surface to go straight through the concrete to the ground below.This water flow is one of the benefit of using the pervious concrete. Using of wastes such as broken roof and ceramics tiles are not commonly used in Indonesia. Utilization these kind of wastes is predicted lower the compressive strength of pervious concrete as they are used as a substitute for coarse aggregate.In this research, pervious concrete is made using a mixture of the fragment of ceramics and roof tiles.This research using broken ceramics and roof tiles with a grain size that loose from 38 mm sieve, retained on 19 mm sieve and the coarse aggregate from crushed stone that loose 12.5 mm sieve, retained on 9.5 mm sieve. The water cement ratio is 0.3 and to assist the mixing process, the addition of addictive in pervious concrete is used.The size of coarse aggregate used in the mixture affects the strength of pervious concrete. The larger the size of aggregate, the obtained compressive strength becomes smaller. It also affects the density of pervious concrete. The using of mixture of ceramics and roof tiles only reduce 2 MPa of pervious concrete compressive strength so this mixture can be used as a substitute for coarse aggregate with a maximum portion of 30 %. The high porosity of the specimens causes the reduction of pervious concrete density that affect the compressive strength. This high level of porosity can be seen from the high level of water absorption that exceed the required limit of water infiltration.

  13. The effects of shelf life on the compressive strength of resin-modified glass ionomer cement

    Science.gov (United States)

    Wajong, K. H.; Damiyanti, M.; Irawan, B.

    2017-08-01

    Resin-modified glass ionomer cement (RMGIC) is a restoration material composed of powder and liquid whose stability is affected by its shelf life. This is an issue that has not been taken into consideration by customers or sellers. To observe the effects of shelf life on the compressive strength of RMGIC, 30 cylindrical (d = 4mm and t = 6mm) specimens of RMGIC (Fuji II LC, GC, Tokyo, Japan) were divided into three groups with different storage times and their compressive strength was tested with a universal testing machine. Results were statistically analyzed with the one-way ANOVA test. There were significant differences (pvalue along with the duration of storage time.

  14. The effects of K2SO4 solution on the compressive strength of dental gypsum type III

    Science.gov (United States)

    Adeilina, T.; Triaminingsih, S.; Indrani, D. J.

    2017-08-01

    Dental gypsum type III is used as a material for manufacturing working models of dentures. The aim of this study was to identify the effects of the addition of a K2SO4 solution on the compressive strength of gypsum type III. A compressive strength test was performed using a universal testing machine with a crosshead speed of 1 mm/min. The data were analyzed using a one-way ANOVA. The results showed that the compressive strength of gypsum type III with a 1.5% K2SO4 solution added was higher than for gypsum type III alone but lower than the compressive strength of gypsum type IV.

  15. High Strength Silicon Carbide Foams and Their Deformation Behavior

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Silicon carbide (SiC) foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 1.3 g/cm3, with corresponding compressive strengths ranging from about 13 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.

  16. The ultimate strength of doubler plate reinforced Y-joints under compression loading

    Institute of Scientific and Technical Information of China (English)

    FENQ Qi; TAN Jia-hua

    2005-01-01

    It is common practice in the offshore industry to solve the punching shear problem due to compression by using doubler plate. The finite-element method is a useful tool for studying this problem. The aim of this paper is to study the static strength of doubler plate reinforced Y-joints subjected to compression loading. The finite-element method is adopted in numerical parametric studies. The individual influences of the geometric parameters βand τd (doubler plate to chord wall thickness ratio) and ld/d1(dubler plate length to brace diameter ratio) on the ultimate strength are made clear. The results show the size of plate may have important effects on the strength of reinforced joints. It is found that the ultimate strength of Y-joints reinforced with appropriately proportioned doubler plates can be greatly improved nearly up tothree times to un-reinforced Y-joints.

  17. Research on Stress and Strength of High Strength Reinforced Concrete Drilling Shaft Lining in Thick Top Soils

    Institute of Scientific and Technical Information of China (English)

    YAO Zhi-shu; CHANG Hua; RONG Chuan-xin

    2007-01-01

    High strength reinforced concrete drilling shaft linings have been adopted to solve the difficult problem of supporting coal drilling shafts penetrating through thick top soils. Through model experiments the stress and strength of such shaft linings are studied. The test results indicate that the load bearing capacity of the shaft lining is very high and that the main factors affecting the load bearing capacity are the concrete strength, the ratio of lining thickness to inner radius and the reinforcement ratio. Based on the limit equilibrium conditions and the strength theory of concrete under multi-axial compressive stressed state, a formula for calculating the load-bearing capacity of a high strength reinforced concrete shaft lining was obtained. Because the concrete in a shaft lining is in a multi-axial compressive stress state the compressive strength increases to a great extent compared to uni-axial loading. Based on experiment a formula for the gain factor in compressive strength was obtained: it can be used in the structural design of the shaft lining. These results have provided a basis for sound engineering practice when designing this kind of shaft lining structure.

  18. Compressive behaviour at High Temperatures of Fibre Reinforced Concretes

    Directory of Open Access Journals (Sweden)

    S. O. Santos

    2009-01-01

    Full Text Available This paper summarizes the research that is being carried out at the Universities of Coimbra and Rio de Janeiro, on fibre reinforced concretes at high temperatures. Several high strength concrete compositions reinforced with fibres (polypropylene, steel and glass fibres were developed. The results of compressive tests at high temperatures (300 °C, 500 °C and 600 °C and after heating and cooling down of the concrete are presented in the paper. In both research studies, the results indicated that polypropylene fibers prevent concrete spalling. 

  19. The Effect of Cyclic Loading on the Compressive Strength of Core Build-Up Materials.

    Science.gov (United States)

    Zankuli, Muayed A; Silikas, Nick; Devlin, Hugh

    2015-01-15

    To evaluate the effect of cyclic loading on compressive strength of core build-up materials. Four dual-cured composites (Core.X Flow, Grandio Core, Bright Flow Core, Spee-Dee) and one light-cured reinforced resin-modified glass ionomer (Fuji II LC) were tested. One hundred cylindrical specimens (4 mm × 6 mm) were prepared. Each material had two groups (ten specimens to be tested under static loading and ten specimens to be tested after cyclic loading). The specimens were stored wet, and after 30 days, one group of each material was cyclically loaded (for 250,000 cycles with a frequency of 1.6 Hz under stress load of 68.6 N) in a chewing simulator CS-4.2. Then specimens were subjected to static compressive loading until failure in a universal testing machine. Mean compressive strength values before cycling ranged from 144 MPa (15.8) for Fuji II LC to 277 MPa (23.2) for Grandio Core. Independent t-test showed no statistically significant difference (p > 0.05) in the compressive strength of each material before and after cycling (p = 0.7 Grandio Core, p = 0.3 Core.X Flow, p = 0.6 Bright Flow Core, p = 0.2 Spee-Dee, p = 0.6 Fuji II LC); however, there was a statistically significant difference between the materials when comparing before and after cycling. All tested materials showed no reduction in the compressive strength after cycling. Therefore, the tested materials can survive 1 year in service without a reduction in compressive strength. © 2015 by the American College of Prosthodontists.

  20. Compressive sensing for high resolution radar imaging

    NARCIS (Netherlands)

    Anitori, L.; Otten, M.P.G.; Hoogeboom, P.

    2010-01-01

    In this paper we present some preliminary results on the application of Compressive Sensing (CS) to high resolution radar imaging. CS is a recently developed theory which allows reconstruction of sparse signals with a number of measurements much lower than what is required by the Shannon sampling th

  1. Sieving hydrogen based on its high compressibility

    Science.gov (United States)

    Chen, Hangyan; Sun, Deyan; Gong, Xingao; Liu, Zhifeng

    2011-03-01

    Based on carbon nanotube intramolecular junction and a C60, a molecular sieve for hydrogen is presented. The small interspace between C60 and junction provides a size changeable channel for the permselectivity of hydrogen while blocking Ne and Ar. The sieving mechanism is due to the high compressibility of hydrogen.

  2. A Novel TiNi/AlSi Composite with High Strength and High Damping Capacity

    Institute of Scientific and Technical Information of China (English)

    Shuwei LIU; Xiuyan LI; Desheng YAN; Haichang JIANG; Lijian RONG

    2008-01-01

    A novel TiNi/AlSi composite with high compressive strength and high damping capacity was obtained by infiltrating Al-12%Si alloy into porous TiNi alloy.It had been found that the high compressive strength (440 MPa) of TiNi/AlSi composite is due to the increase of effective carrying area after infiltrating Al-12%Si alloy,while the high damping capacity is contributed to TiNi carcass,Al-12%Si filling material and micro-slipping at the interface.

  3. High pressure, high strain rate material strength studies

    Science.gov (United States)

    Remington, B. A.; Arsenlis, A.; Barton, N.; Belof, J.; Cavallo, R.; Maddox, B.; Park, H.-S.; Prisbrey, S.; Rudd, R.; Comley, A.; Meyers, M.; Wark, J.

    2011-10-01

    Constitutive models for material strength are currently being tested at high pressures by comparing 2D simulations with experiments measuring the Rayleigh-Taylor (RT) instability evolution in solid-state samples of vanadium (V), tantalum (Ta), and iron (Fe). The multiscale strength models being tested combine molecular dynamics, dislocation dynamics, and continuum simulations. Our analysis for the V experiments suggests that the material deformation at these conditions falls into the phonon drag regime, whereas for Ta, the deformation resides mainly in the thermal activation regime. Recent Fe-RT experiments suggest perturbation growth about the alpha-epsilon (bcc-hcp) phase transition threshold has been observed. Using the LLNL multiscale models, we decompose the strength as a function of strain rate into its dominant components of thermal activation, phonon drag, and work hardening. We have also developed a dynamic diffraction diagnostic technique to measure strength directly from shock compressed single crystal samples. Finally, recovery experiments allow a comparison of residual dislocation density with predictions from the multiscale model. This work performed under the auspices of the U.S. DoE by LLNL Security, LLC under Contract DE-AC52-07NA27344.

  4. Prediction of Human Vertebral Compressive Strength Using Quantitative Computed Tomography Based Nonlinear Finite Element Method

    Directory of Open Access Journals (Sweden)

    Ahad Zeinali

    2007-12-01

    Full Text Available Introduction: Because of the importance of vertebral compressive fracture (VCF role in increasing the patients’ death rate and reducing their quality of life, many studies have been conducted for a noninvasive prediction of vertebral compressive strength based on bone mineral density (BMD determination and recently finite element analysis. In this study, QCT-voxel based nonlinear finite element method is used for predicting vertebral compressive strength. Material and Methods: Four thoracolumbar vertebrae were excised from 3 cadavers with an average age of 42 years. They were then put in a water phantom and were scanned using the QCT. Using a computer program prepared in MATLAB, detailed voxel based geometry and mechanical characteristics of the vertebra were extracted from the CT images. The three dimensional finite element models of the samples were created using ANSYS computer program. The compressive strength of each vertebra body was calculated based on a linearly elastic-linearly plastic model and large deformation analysis in ANSYS and was compared to the value measured experimentally for that sample. Results: Based on the obtained results the QCT-voxel based nonlinear finite element method (FEM can predict vertebral compressive strength more effectively and accurately than the common QCT-voxel based linear FEM. The difference between the predicted strength values using this method and the measured ones was less than 1 kN for all the samples. Discussion and Conclusion: It seems that the QCT-voxel based nonlinear FEM used in this study can predict more effectively and accurately the vertebral strengths based on every vertebrae specification by considering their detailed geometric and densitometric characteristics.

  5. Evaluation of Early-Age Concrete Compressive Strength with Ultrasonic Sensors.

    Science.gov (United States)

    Yoon, Hyejin; Kim, Young Jin; Kim, Hee Seok; Kang, Jun Won; Koh, Hyun-Moo

    2017-08-07

    Surface wave velocity measurement of concrete using ultrasonic sensors requires testing on only one side of a member. Thus, it is applicable to concrete cast inside a form and is often used to detect flaws and evaluate the compressive strength of hardened concrete. Predicting the in situ concrete strength at a very early stage inside the form helps with determining the appropriate form removal time and reducing construction time and costs. In this paper, the feasibility of using surface wave velocities to predict the strength of in situ concrete inside the form at a very early stage was evaluated. Ultrasonic sensors were used to measure a series of surface waves for concrete inside a form in the first 24 h after placement. A continuous wavelet transform was used to compute the travel time of the propagating surface waves. The cylindrical compressive strength and penetration resistance tests were also performed during the test period. Four mixtures and five curing temperatures were used for the specimens. The surface wave velocity was confirmed to be applicable to estimating the concrete strength at a very early age in wall-like elements. An empirical formula is proposed for evaluating the early-age compressive strength of concrete considering the 95% prediction intervals.

  6. Influence of Mechanically Activated Electric Arc Furnace Slag on Compressive Strength of Mortars Incorporating Curing Moisture and Temperature Effects

    Directory of Open Access Journals (Sweden)

    Muhammad Nasir Amin

    2017-07-01

    Full Text Available In this study, the influence of mechanically activated electric arc furnace slag (EAFS was investigated through compressive strength tests on 50 mm mortar cubes. The objective was to convert the wasteful EAFS into a useful binding material to reduce the cement content in concrete without compromising strength and economy. Four different groups of mortar were cast which include control mortar, reference fly ash mortar, mortar containing EAFS to determine its optimum fineness and replacement with cement, mortar blend containing fly ash and EAFS of optimum fineness. EAFS were identified with respect to its fineness as slag ground (SG, slag-fine (SF 100% passing 75 µm sieve, and slag-super-fine (SSF 100% passing 45 µm sieve. Compressive strength was measured according to ASTM C109. Specimens were cured under different temperatures and moisture to incorporate the effects of normal and hot environmental conditions. Compressive strength of mortars increases with fineness of EAFS and its strength activity index matches the ASTM C989 blast furnace slag (BFS Grade 80 up to 30% cement substitution and Grade 100 when 10% cement substituted with SSF. The influence of curing temperatures was also significant in mortars containing SG or 10% SF where strength decreased with increasing curing temperature. However, a 20–30% and 20% cement substitution with SF produced strength comparable to control and reference fly ash mortars under moderate (40 °C and high curing temperature (60 °C, respectively. The utilization of EAFS as binder in concrete may reduce needs for cement, as well as save environment and natural resources from depletion.

  7. Experimental and theoretical research on residual strength of plain concrete under compressive fatigue loading

    Institute of Scientific and Technical Information of China (English)

    MENG Xian-hong; SONG Yu-pu

    2008-01-01

    To investigate the residual strength of concrete under fatigue loading, experiments were conducted to determine the functional relation between residual strength and the number of cycles. 80 100mm×100mm×100ram specimens of plain concrete were tested under uniaxial compressive fatigue loading. Based on probabili-ty distribution of the residual strength of concrete under fatigue loading, the empirical expressions of the residual strength corresponding to the number of cycles were obtained. There is a good correlation between residual strength and residual secant elastic modulus. Thus the relationship between residual secant elastic modulus and the number of cycles is established. A damage variable based on the longitudinal maximum strain is defined, and a good linearity relationship between residual strength and damage is found out.

  8. Effects of GFF Bands on Normal and High Strength Concrete Cylinders

    OpenAIRE

    Jayaprakash, J; Abdul Aziz Abdul Samad; Noridah Mohamad; K.K. Choong; M.J. Megat Azmi; H.A.B. Badorul

    2010-01-01

    This paper exemplifies the effects of externally confined Glass Fibre Fabric (GFF) bands on normal and high strength concrete cylinders. Twelve normal and high strength concrete cylinders were cast and tested in the laboratory environment under axial compression to failure. The experimental results show that the degree of confinement of discrete GFF confined high strength concrete cylinders was significantly better than normal strength concrete cylinders with GFF bands, however...

  9. Compressive strength and heavy metal leaching behaviour of mortars containing spent catalyst.

    Science.gov (United States)

    Rattanasak, U; Jaturapitakkul, C; Sudaprasert, T

    2001-10-01

    This investigation was set and aimed to study the possibility of using spent catalyst as a concrete constituent which the spent catalyst was used as sand. Besides the spent catalyst was used as sand, it was also ground to very small particle size as small as that of cement and used as 20% replacement of cement by weight. Compressive strengths and leaching characteristics of lead, chromium, cadmium, and nickel in mortars containing spent catalyst and ground spent catalyst were tested. The results presented revealed that the compressive strength of mortar containing spent catalyst increased with ages. The results also indicated that the compressive strength of mortar containing spent catalyst at the proportion of 1.25 times of cement by weight was strong enough to make a concrete brick. In case of the ground spent catalyst being used to replace cement, it made the compressive strength lower than that of the standard mortar approximately 20%. The leachate results of lead and chromium from spent catalyst were lower than the allowance, but cadmium and nickel exceeded the limits. After the spent catalyst was fixed with cement, the leaching of the heavy metals did not exceed the industrial effluent standard. Therefore, the heavy metals mentioned earlier were not a problem in using spent catalyst as a concrete constituent.

  10. The Effect of Polymer-Cement Stabilization on the Unconfined Compressive Strength of Liquefiable Soils

    Directory of Open Access Journals (Sweden)

    Ali Ateş

    2013-01-01

    Full Text Available Soil stabilization has been widely used as an alternative to substitute the lack of suitable material on site. The use of nontraditional chemical stabilizers in soil improvement is growing daily. In this study a laboratory experiment was conducted to evaluate the effects of waterborne polymer on unconfined compression strength and to study the effect of cement grout on pre-venting of liquefiable sandy soils. The laboratory tests were performed including grain size of sandy soil, unit weight, ultrasonic pulse velocity, and unconfined compressive strength test. The sand and various amounts of polymer (1%, 2%, 3%, and 4% and cement (10%, 20%, 30%, and 40% were mixed with all of them into dough using mechanical kneader in laboratory conditions. Grouting experiment is performed with a cylindrical mould of  mm. The samples were subjected to unconfined compression tests to determine their strength after 7 and 14 days of curing. The results of the tests indicated that the waterborne polymer significantly improved the unconfined compression strength of sandy soils which have susceptibility of liquefaction.

  11. Prediction of Corrosion Resistance of Concrete Containing Natural Pozzolan from Compressive Strength

    Science.gov (United States)

    al-Swaidani, A. M.; Ismat, R.; Diyab, M. E.; Aliyan, S. D.

    2015-11-01

    A lot of Reinforced Concrete (RC) structures in Syria have suffered from reinforcement corrosion which shortened significantly their service lives. Probably, one of the most effective approaches to make concrete structures more durable and concrete industry on the whole - more sustainable is to substitute pozzolan for a portion of Portland cement (PC). Syria is relatively rich in natural pozzolan. In the study, in order to predict the corrosion resistance from compressive strength, concrete specimens were produced with seven cement types: one plain Portland cement (control) and six natural pozzolan-based cements with replacement levels ranging from 10 to 35%. The development of the compressive strengths of concrete cube specimens with curing time has been investigated. Chloride penetrability has also been evaluated for all concrete mixes after three curing times of 7, 28 and 90 days. The effect on resistance of concrete against damage caused by corrosion of the embedded reinforcing steel has been investigated using an accelerated corrosion test by impressing a constant anodic potential for 7, 28 and 90 days curing. Test results have been statistically analysed and correlation equations relating compressive strength and corrosion performance have been developed. Significant correlations have been noted between the compressive strength and both rapid chloride penetrability and corrosion initiation times. So, this prediction could be reliable in concrete mix design when using natural pozzolan as cement replacement.

  12. modified water-cement ratio law for compressive strength of rice ...

    African Journals Online (AJOL)

    user

    Chemical analysis of RHA produced under controlled temperature of 600°C was carried out. A ... Test results show that the compressive strength of hardened RHA concrete ..... by [22]. However the loss on ignition (LOI) of 13.33 is lower.

  13. Effects of CuO nanoparticles on compressive strength of self-compacting concrete

    Indian Academy of Sciences (India)

    Ali Nazari; Shadi Riahi

    2011-06-01

    In the present study, the compressive strength, thermal properties and microstructure of self-compacting concrete with different amounts of CuO nanoparticles have been investigated. CuO nanoparticles with an average particle size of 15 nm were added to self-compacting concrete and various properties of the specimens were measured. The results indicate that CuO nanoparticles are able to improve the compressive strength of self-compacting concrete and reverse the negative effects of superplasticizer on compressive strength of the specimens. CuO nanoparticles as a partial replacement of cement up to 4 wt.% could accelerate C–S–H gel formation as a result of the increased crystalline Ca(OH)2 amount at the early ages of hydration. Increasing CuO nanoparticle content to more than 4 wt.%, causes reduced compressive strength because of unsuitable dispersion of nanoparticles in the concrete matrix. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of peaks related to hydrated products in X-ray diffraction results, all indicate that CuO nanoparticles up to 4 wt.% could improve the mechanical and physical properties of the specimens. Finally, CuO nanoparticles improved the pore structure of concrete and caused shifting of the distributed pores from harmless to low harm.

  14. Prediction of compressive strength up to 28 days from microstructure of Portland cement

    DEFF Research Database (Denmark)

    Svinning, K.; Høskuldsson, Agnar; Justnes, H.

    2008-01-01

    The influence of the characteristics or the microstructure of Portland cement on compressive strength up to 28 days has been statistically investigated by application of partial least square (PLS) analysis. The main groups of characteristics were mineralogy and superficial microstructure represen...

  15. Compression strength of sandwich panels with sub-interface damage in the foam core

    NARCIS (Netherlands)

    Koysin, V.; Shipsha, Andrey; Skvortsov, Vitaly

    2009-01-01

    This paper addresses the effect of a local quasi-static indentation or a low-velocity impact on the residual strength of foam core sandwich panels subjected to edgewise compression. The damage is characterized by a local zone of crushed core accompanied by a residual dent in the face sheet.

  16. The Effects of Different Curing Methods on the Compressive Strength of Terracrete

    Directory of Open Access Journals (Sweden)

    O. Alake

    2009-01-01

    Full Text Available This research evaluated the effects of different curing methods on the compressive strength of terracrete. Several tests that included sieve analysis were carried out on constituents of terracrete (granite and laterite to determine their particle size distribution and performance criteria tests to determine compressive strength of terracrete cubes for 7 to 35 days of curing. Sand, foam-soaked, tank and open methods of curing were used and the study was carried out under controlled temperature. Sixty cubes of 100 × 100 × 100mm sized cubes were cast using a mix ratio of 1 part of cement, 1½ part of latrite, and 3 part of coarse aggregate (granite proportioned by weight and water – cement ratio of 0.62. The result of the various compressive strengths of the cubes showed that out of the four curing methods, open method of curing was the best because the cubes gained the highest average compressive strength of 10.3N/mm2 by the 35th day.

  17. The Effect of Blood Contamination on the Compressive Strength of Calcium-Enriched Mixture

    Directory of Open Access Journals (Sweden)

    Alireza Adl

    2015-03-01

    Full Text Available Statement of the Problem: In clinical situations, Calcium-Enriched Mixture (CEM comes into direct contact or even mixes with blood during or after placement. Purpose: The aim of this study was to evaluate the effect of blood contamination on the compressive strength of CEM. Materials and Method: Three experimental groups were included in this study. In the first group, CEM was mixed with distilled water and was exposed to normal saline (control group. In the second group, CEM cement was mixed with distilled water and then was exposed to blood. In the third group, CEM was mixed with and exposed to blood. Nine custom-made two-part split Plexiglas molds with five holes were used to form CEM samples for compressive strength testing (15 samples in each group. After 7 days of incubation, compressive bond strength testing was performed using a universal testing machine. Data were statistically analyzed using the Mann–Whitney U test with a significance level of p 0.05. Conclusion: It can be concluded that exposure to blood does not adversely affect the compressive strength of CEM, but incorporation of blood makes the cement very brittle.

  18. Effect of Impact Damage and Open Hole on Compressive Strength of Hybrid Composite Laminates

    Science.gov (United States)

    Hiel, Clement; Brinson, H. F.

    1993-01-01

    Impact damage tolerance is a frequently listed design requirement for composites hardware. The effect of impact damage and open hole size on laminate compressive strength was studied on sandwich beam specimens which combine CFRP-GFRP hybrid skins and a syntactic foam core. Three test specimen configurations have been investigated for this study. The first two were sandwich beams which were loaded in pure bending (by four point flexure). One series had a skin damaged by impact, and the second series had a circular hole machined through one of the skins. The reduction of compressive strength with increasing damage (hole) size was compared. Additionally a third series of uniaxially loaded open hole compression coupons were tested to generate baseline data for comparison with both series of sandwich beams.

  19. Damage Characteristics and Residual Strength of Composite Sandwich Panels Impacted with and Without Compression Loading

    Science.gov (United States)

    McGowan, David M.; Ambur, Damodar R.

    1998-01-01

    The results of an experimental study of the impact damage characteristics and residual strength of composite sandwich panels impacted with and without a compression loading are presented. Results of impact damage screening tests conducted to identify the impact-energy levels at which damage initiates and at which barely visible impact damage occurs in the impacted facesheet are discussed. Parametric effects studied in these tests include the impactor diameter, dropped-weight versus airgun-launched impactors, and the effect of the location of the impact site with respect to the panel boundaries. Residual strength results of panels tested in compression after impact are presented and compared with results of panels that are subjected to a compressive preload prior to being impacted.

  20. Effect of Sample Disturbance on Unconfined Compression Strength of Natural Marine Clays

    Institute of Scientific and Technical Information of China (English)

    刘汉龙; 洪振舜

    2003-01-01

    Quantitatively correcting the unconfined compressive strength for sample disturbance is an important research project in the practice of ocean engineering and geotechnical engineering. In this study, the specimens of undisturbed natural marine clay obtained from the same depth at the same site were deliberately disturbed to different levels. Then, the specimens with different extents of sample disturbance were trimmed for both oedometer tests and unconfined compression tests. The degree of sample disturbance SD is obtained from the oedometer test data. The relationship between the unconfined compressive strength qu and SD is studied for investigating the effect of sample disturbance on qu. It is found that the value of qu decreases linearly with the increase in SD. Then, a simple method of correcting qu for sample disturbance is proposed. Its validity is also verified through analysis of the existing published data.

  1. Effect of Oral Tissue Fluids on Compressive Strength of MTA and Biodentine: An In vitro Study.

    Science.gov (United States)

    Subramanyam, Divya; Vasantharajan, Madhusudhan

    2017-04-01

    Over the past many years various root end filling materials have been used which have been tested for their physical properties but each of them had certain limitations. In clinical practice, root end filling materials are exposed to oral tissue fluids which may compromise their longevity. The aim of this study was to investigate the effects of oral tissue fluids on compressive strength of Mineral Trioxide Aggregate (MTA) and biodentine. MTA and biodentine cylinders measuring 6 mm × 4 mm were prepared using acrylic blocks. They were divided into six groups; (Group 1) (MTA) (n=3), (Group 2) MTA contaminated with saliva, (MTA-S) (n=3), Group 3: MTA contaminated with blood, MTA-B (n=3), Group 4: Biodentine (BD), Group 5: Biodentine contaminated with saliva (BD-S) (n=5), Group 6: Biodentine contaminated with blood (BD-B) (n=5). The mould was contaminated with saliva and blood and incubated at 37°C at 100% humidity for three days and compressive strength (MPa) was measured using universal testing machine and the data was analyzed statistically using one-way ANOVA test. There was no significant difference in the compressive strength between the three groups i.e., MTA, MTA-S, MTA-B (p > 0.05). However, there was higher compressive strength in the MTA-B group when compared to MTA and MTA-S. Also, there was no statistical significant difference between BD, BD-S, BD-B (p>0.05). This study showed that the compressive strength of MTA and biodentine was not adversely affected by contamination with oral tissue fluids like blood and saliva.

  2. Compressive strength of dental composites photo-activated with different light tips

    Science.gov (United States)

    Galvão, M. R.; Caldas, S. G. F. R.; Calabrez-Filho, S.; Campos, E. A.; Bagnato, V. S.; Rastelli, A. N. S.; Andrade, M. F.

    2013-04-01

    The aim of this study was to evaluate the compressive strength of microhybrid (Filtek™ Z250) and nanofilled (Filtek™ Supreme XT) composite resins photo-activated with two different light guide tips, fiber optic and polymer, coupled with one LED. The power density was 653 mW cm-2 when using the fiber optic light tip and 596 mW cm-2 with the polymer. After storage in distilled water at 37 ± 2 °C for seven days, the samples were subjected to mechanical testing of compressive strength in an EMIC universal mechanical testing machine with a load cell of 5 kN and speed of 0.5 mm min-1. The statistical analysis was performed using ANOVA with a confidence interval of 95% and Tamhane’s test. The results showed that the mean values of compressive strength were not influenced by the different light tips (p > 0.05). However, a statistical difference was observed (p composite resin photo-activated with the fiber optic light tip and the nanofilled composite resin. Based on these results, it can be concluded that microhybrid composite resin photo-activated with the fiber optic light tip showed better results than nanofilled, regardless of the tip used, and the type of the light tip did not influence the compressive strength of either composite. Thus, the presented results suggest that both the fiber optic and polymer light guide tips provide adequate compressive strength to be used to make restorations. However, the fiber optic light tip associated with microhybrid composite resin may be an interesting option for restorations mainly in posterior teeth.

  3. Effect of Oral Tissue Fluids on Compressive Strength of MTA and Biodentine: An In vitro Study

    Science.gov (United States)

    Vasantharajan, Madhusudhan

    2017-01-01

    Introduction Over the past many years various root end filling materials have been used which have been tested for their physical properties but each of them had certain limitations. In clinical practice, root end filling materials are exposed to oral tissue fluids which may compromise their longevity. Aim The aim of this study was to investigate the effects of oral tissue fluids on compressive strength of Mineral Trioxide Aggregate (MTA) and biodentine. Materials and Methods MTA and biodentine cylinders measuring 6 mm × 4 mm were prepared using acrylic blocks. They were divided into six groups; (Group 1) (MTA) (n=3), (Group 2) MTA contaminated with saliva, (MTA-S) (n=3), Group 3: MTA contaminated with blood, MTA-B (n=3), Group 4: Biodentine (BD), Group 5: Biodentine contaminated with saliva (BD-S) (n=5), Group 6: Biodentine contaminated with blood (BD-B) (n=5). The mould was contaminated with saliva and blood and incubated at 37°C at 100% humidity for three days and compressive strength (MPa) was measured using universal testing machine and the data was analyzed statistically using one-way ANOVA test. Results There was no significant difference in the compressive strength between the three groups i.e., MTA, MTA-S, MTA-B (p > 0.05). However, there was higher compressive strength in the MTA-B group when compared to MTA and MTA-S. Also, there was no statistical significant difference between BD, BD-S, BD-B (p>0.05). Conclusion This study showed that the compressive strength of MTA and biodentine was not adversely affected by contamination with oral tissue fluids like blood and saliva. PMID:28571272

  4. Optimum Compressive Strength of Hardened Sandcrete Building Blocks with Steel Chips

    Directory of Open Access Journals (Sweden)

    Alohan Omoregie

    2013-02-01

    Full Text Available The recycling of steel chips into an environmentally friendly, responsive, and profitable commodity in the manufacturing and construction industries is a huge and difficult challenge. Several strategies designed for the management and processing of this waste in developed countries have been largely unsuccessful in developing countries mainly due to its capital-intensive nature. To this end, this investigation attempts to provide an alternative solution to the recycling of this material by maximizing its utility value in the building construction industry. This is to establish their influence on the compressive strength of sandcrete hollow blocks and solid cubes with the aim of specifying the range percent of steel chips for the sandcrete optimum compressive strength value. This is particularly important for developing countries in sub-Saharan Africa, and even Latin America where most sandcrete blocks exhibit compressive strengths far below standard requirements. Percentages of steel chips relative to the weight of cement were varied and blended with the sand in an attempt to improve the sand grading parameters. The steel chips variations were one, two, three, four, five, ten and fifteen percent respectively. It was confirmed that the grading parameters were improved and there were significant increases in the compressive strength of the blocks and cube samples. The greatest improvement was noticed at four percent steel chips and sand combination. Using the plotted profile, the margin of steel chips additions for the optimum compressive strength was also established. It is recommended that steel chip sandcrete blocks are suitable for both internal load bearing, and non-load bearing walls, in areas where they are not subjected to moisture ingress. However, for external walls, and in areas where they are liable to moisture attack after laying, the surfaces should be well rendered. Below ground level, the surfaces should be coated with a water

  5. Effect of pH and Lidocaine on the Compressive Strength of Calcium Enriched Mixture Cement

    Directory of Open Access Journals (Sweden)

    Sobhnamayan F

    2015-12-01

    Full Text Available Statement of Problem: The pH of the human abscess has been measured as low as 5.0. This low pH could potentially inhibit setting reactions, affect adhesion, or increase the solubility of root end filling materials hence affect the compressive strength. Moreover, root end filling materials might expose or even mix with lidocaine HCL during periapical surgery. Objectives: The aim of this in vitro study was to evaluate the effect of acidic pH and lidocaine on the compressive strength of calcium-enriched mixture (CEM. Materials and Methods: CEM was mixed according to the manufacturer’s instructions or with lidocaine (L, and condensed into 6 × 4 mm split moulds. The samples were exposed to phosphate buffered saline (PBS at pH 5 or 7.4 for 7 or 28 days. Cylindrical blocks of CEM (total number = 120 and 15 for each group were subjected to compressive strength test using a universal testing machine. Data were analysed using three-factor analysis of variance (ANOVA. Results: Regardless of pH and time, significant differences were not found between lidocaine groups and the groups that were mixed according to the manufacturer’s instruction (p = 0.083. For both mixing agents, regardless of time, there were no significant differences between the two pH levels (p = 0.157. Regardless of the material and pH, there was a significant increase in the compressive strength from days 7 to 28 (p < 0.001. Conclusions: Mixtures with lidocaine and exposure to an acidic environment had no adverse effects on the compressive strength of CEM Cement.

  6. High-strength concrete for Peacekeeper facilities

    Science.gov (United States)

    Saucier, K. L.

    1984-03-01

    An investigation is described which was conducted to determine the processes and techniques required to produce portland-cement concrete with a compressive strength of 15,000 psi or greater using conventional concreting methods and equipment, and to develop physical property data on the mixtures. It was permitted that special materials and admixtures be used, but a requirement was set that the aggregates and cements be selected from those available in the Cheyenne, Wyoming, area. Results indicated that it is feasible to achieve the 15,000-psi compressive strengths but that workability may decrease over a 2-hour period, and this latter development should be studied under job conditions. It is recommended that: (1) all materials and procedures to be used on a specific project be tested in the laboratory for basic property information, and (2) selected mixtures be tested in the field under expected environmental conditions prior to actual job use.

  7. Investigation of Noise Level and Penetration Rate of Pneumatic Drill vis-à-vis Rock Compressive Strength and Abrasivity

    Science.gov (United States)

    Kivade, S. B.; Murthy, Ch. S. N.; Vardhan, H.

    2014-10-01

    In this paper, detailed studies were carried out to determine the influence of rock properties on the sound level produced during pneumatic drilling. Further, investigation was also carried out on the effect of thrust, air pressure and compressive strength on penetration rate and the sound level produced. For this purpose, a fabricated pneumatic drill set up available in the institute was used. Rock properties, like compressive strength and abrasivity, of various samples collected from the field were determined in the laboratory. Drilling experiments were carried out on ten different rock samples for varying thrust and air pressure values and the corresponding A-weighted equivalent continuous sound levels were measured. It was observed that, very low thrust results in low penetration rate. Even very high thrust does not produce high penetration rate at higher operating air pressures. With increase in thrust beyond the optimum level, the penetration rate starts decreasing and causes the drill bit to `stall'. Results of the study show that penetration rate and sound level increases with increase in the thrust level. After reaching the maximum, they start decreasing despite the increase of thrust. The main purpose of the study is to develop a general prediction model and to investigate the relationships between sound level produced during drilling and physical properties such as uniaxial compressive strength and abrasivity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of predictor variables.

  8. Compressive Strength and Static Modulus of Elasticity of Periwinkle Shell Ash Blended Cement Concrete

    Directory of Open Access Journals (Sweden)

    Akaninyene Afangide Umoh

    2012-12-01

    Full Text Available The study examined the effect of periwinkle shell ash as supplementary cementitious material on the compressive strength and static modulus of elasticity of concrete with a view to comparing it’s established relation with an existing model. The shells were calcined at a temperature of 800oC. Specimens were prepared from a mix of designed strength 25N/mm2. The replacement of cement with periwinkle shell ash (PSA was at five levels of 0, 10, 20, 30 and 40% by volume. A total of 90 cubical and cylindrical specimens each were cast and tested at 7, 14, 28, 90, 120 and 180 days. The results revealed that the PSA met the minimum chemical and physical requirements for class C Pozzolans. The compressive strength of the PSA blended cement concrete increased with increase in curing age up to 180 days but decreased as the PSA content increased. The design strength was attained with 10%PSA content at the standard age of 28 days. The static modulus of elasticity of PSA blended cement concrete was observed to increase with increased in curing age and decreases with PSA content. In all the curing ages 0%PSA content recorded higher value than the blended cement concrete. The statistical analysis indicated that the percentage PSA replacement and the curing age have significant effect on the properties of the concrete at 95% confidence level. The relation between compressive strength and static modulus of elasticity fitted into existing model for normal-weight concrete.

  9. Effect of dilute tungsten alloying on the dynamic strength of tantalum under ramp compression

    Science.gov (United States)

    Alexander, C. S.; Brown, J. L.; Millett, J. C. F.; Whiteman, G.; Asay, J. R.; Bourne, N. K.

    2015-06-01

    The strength of tantalum and tantalum alloys are of considerable interest due to their widespread use in both military and industrial applications. Previous work has shown that strength in these materials is tied to dislocation density and mobility within the microstructure. Accordingly, strength has been observed to increase with dilute alloying which serves to increase the dislocation density. In this study, we examine the effect of alloying on the strength of a dilute tantalum-tungsten alloy (2.5 weight percent W) under ramp compression. The strength of the alloy is measured using the ``self-consistent'' technique which examines the response under longitudinal unloading from peak compression. The results are compared to previous studies of pure tantalum and dilute tantalum-tungsten alloys under both shock and ramp compression and indicate strengthening of the alloy when compared to pure tantalum. Sandia National Labs is a multi-program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  10. Dynamic High-Temperature Characterization of an Iridium Alloy in Compression at High Strain Rates

    Energy Technology Data Exchange (ETDEWEB)

    Song, Bo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Experimental Environment Simulation Dept.; Nelson, Kevin [Sandia National Lab. (SNL-CA), Livermore, CA (United States). Mechanics of Materials Dept.; Lipinski, Ronald J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Fuel Cycle Technology Dept.; Bignell, John L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Structural and Thermal Analysis Dept.; Ulrich, G. B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program; George, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Radioisotope Power Systems Program

    2014-06-01

    Iridium alloys have superior strength and ductility at elevated temperatures, making them useful as structural materials for certain high-temperature applications. However, experimental data on their high-temperature high-strain-rate performance are needed for understanding high-speed impacts in severe elevated-temperature environments. Kolsky bars (also called split Hopkinson bars) have been extensively employed for high-strain-rate characterization of materials at room temperature, but it has been challenging to adapt them for the measurement of dynamic properties at high temperatures. Current high-temperature Kolsky compression bar techniques are not capable of obtaining satisfactory high-temperature high-strain-rate stress-strain response of thin iridium specimens investigated in this study. We analyzed the difficulties encountered in high-temperature Kolsky compression bar testing of thin iridium alloy specimens. Appropriate modifications were made to the current high-temperature Kolsky compression bar technique to obtain reliable compressive stress-strain response of an iridium alloy at high strain rates (300 – 10000 s-1) and temperatures (750°C and 1030°C). Uncertainties in such high-temperature high-strain-rate experiments on thin iridium specimens were also analyzed. The compressive stress-strain response of the iridium alloy showed significant sensitivity to strain rate and temperature.

  11. Influence of uncoated and coated plastic waste coarse aggregates to concrete compressive strength

    Directory of Open Access Journals (Sweden)

    Purnomo Heru

    2017-01-01

    Full Text Available The use of plastic waste as coarse aggregates in concrete is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of the concrete than concrete using natural aggregates, but on the other hand bond between plastic coarse aggregates and hard matrix give low concrete compressive strength. Improvement of the bond between plastic coarse aggregate and hard matrix through a sand coating to plastic coarse aggregate whole surface is studied. Sand used to coat the plastic aggregates are Merapi volcanic sand which are taken in Magelang. Three mixtures of polypropylene (PP coarse plastic aggregates, Cimangkok river sand as fine aggregates, water and Portland Cement Composite with a water-cement ratio of 0.28, 0.3 and 0.35 are conducted. Compression test are performed on concrete cylindrical specimens with a diameter of 10 cm and a height of 20 cm. The results in general show that concrete specimens using plastic aggregates coated with sand have higher compressive strength compared to those of concrete specimens using plastic aggregates without sand coating. The bond improvement is indirectly indicated by the betterment of concrete compressive strength.

  12. Evaluation of Compressive Strength and Sorption/Solubility of Four Luting Cements

    Directory of Open Access Journals (Sweden)

    Tavangar MS

    2017-06-01

    Full Text Available Abstract: Statement of Problem: Compressive strength (CS and sorption/solubility of the luting cements are two associated factors. Searching a correlation between sorption/solubility and compressive strength of various luting cements is required. Objectives: To measure the water sorption/solubility, and compressive strength of three resin-based and one conventional glass ionomer (CGI luting cement after 1 and 24 h of immersion in distilled water and to determine if there is any correlation between those properties found. Materials and Methods: Four luting cements were investigated. For each material, 10 disc shaped specimens were prepared for measuring the sorption/solubility. The specimens were cured according to the manufacturer’s instructions, and the sorption/solubility were measured in accordance with the ISO 4049’s. For testing the compression strength, for each material 16 cylindrical specimens were prepared by insertion of cements into a stainless steel split mould. The specimens were cured, divided into groups of 8, and then stored in distilled water at (37 ± 1°C for 1 and 24 h. The test was performed using the universal testing machine, the maximum load was recorded and CS was calculated. The data were analysed using SPSS software version 18. One-way ANOVA, post-hoc Tukey’s test and Pearson’s correlation coefficient were performed. Results: G-CEM had the highest mean CS (153.60± 25.15 and CGI luting had the lowest CS (21.36±5.37 (p 0.05. The lowest mean sorption/solubility value was for RelyXTM U200 and Panavia F, and the highest for CGI luting (all p < 0.001. Conclusions: The compressive strength of all cements did not necessarily increase after 24 h and varied depending on the materials. There was a strong reverse correlation between sorption and CS values after both 1 and 24 h immersion. It may be practical for clinician to use those cements with the less sorption / solubility and more stable compression strength over

  13. High reflection mirrors for pulse compression gratings.

    Science.gov (United States)

    Palmier, S; Neauport, J; Baclet, N; Lavastre, E; Dupuy, G

    2009-10-26

    We report an experimental investigation of high reflection mirrors used to fabricate gratings for pulse compression application at the wavelength of 1.053microm. Two kinds of mirrors are studied: the mixed Metal MultiLayer Dielectric (MMLD) mirrors which combine a gold metal layer with some e-beam evaporated dielectric bilayers on the top and the standard e-beam evaporated MultiLayer Dielectric (MLD) mirrors. Various samples were manufactured, damage tested at a pulse duration of 500fs. Damage sites were subsequently observed by means of Nomarski microscopy and white light interferometer microscopy. The comparison of the results evidences that if MMLD design can offer damage performances rather similar to MLD design, it also exhibits lower stresses; being thus an optimal mirror substrate for a pulse compression grating operating under vacuum.

  14. The influence of nickel slag aggregate concentration to compressive and flexural strength on fly ash-based geopolymer composite

    Science.gov (United States)

    Sujiono, E. H.; Setiawan, A.; Husain, H.; Irhamsyah, A.; Samnur, S.; Subaer, S.

    2016-04-01

    Fly ash-based geopolymer with nickel slag aggregate has been successfully produced. Fly ash and nickel slag were obtained from Bosowa Jeneponto Power Plant and PT. Vale Indonesia, respectively. This research aims to investigate the influence of nickel slag concentration to compressive strength, flexural strength, and microstructure of geopolymer composite. The increment of nickel slag aggregate on fly ash was relative to the weight of samples. Geopolymer composite were synthesized by using alkali activated method, cured at temperature of 70 °C for 1 hour. The resulting composites were left at room temperature for 14 days, before compressive and flexural strength were performed. The results showed that the addition of nickel slag aggregate was found to increase the compressive strength of the material. The optimum compressive strength was 14.81 MPa with the addition of 10% aggregate. The optimum flexural strength was 2.63 MPa with the addition of 15% aggregate.

  15. An in vitro study to compare the transverse strength of thermopressed and conventional compression-molded polymethylmethacrylate polymers

    Directory of Open Access Journals (Sweden)

    Anjana Raut

    2013-01-01

    Full Text Available Statement of Problem: Acrylic resins have been in the center stage of Prosthodontics for more than half a century. The flexural fatigue failure of denture base materials is the primary mode of clinical failure. Hence there is a need for superior physical and mechanical properties. Purpose: This in vitro study compared the transverse strength of specimens of thermopressed injection-molded and conventional compression-molded polymethylmethacrylate polymers and examined the morphology and microstructure of fractured acrylic specimens. Materials and Methods: The following denture base resins were examined: Brecrystal (Thermopressed injection-molded, modified polymethylmethacrylate and Pyrax (compression molded, control group. Specimens of each material were tested according to the American Society for Testing and Materials standard D790-03 for flexural strength testing of reinforced plastics and subsequently examined under SEM. The data was analyzed with Student unpaired t test. Results: Flexural strength of Brecrystal (82.08 ± 1.27 MPa was significantly higher than Pyrax (72.76 ± 0.97 MPa. The tested denture base materials fulfilled the requirements regarding flexural strength (>65 MPa. The scanning electron microscopy image of Brecrystal revealed a ductile fracture with crazing. The fracture pattern of control group specimens exhibited poorly defined crystallographic planes with a high degree of disorganization. Conclusion: Flexural strength of Brecrystal was significantly higher than the control group. Brecrystal showed a higher mean transverse strength value of 82.08 ± 1.27 MPa and a more homogenous pattern at microscopic level. Based on flexural strength properties and handling characteristics, Brecrystal may prove to be an useful alternative to conventional denture base resins.

  16. Electrical resistivity measurement to predict uniaxial compressive and tensile strength of igneous rocks

    Indian Academy of Sciences (India)

    Sair Kahraman; Tekin Yeken

    2010-12-01

    Electrical resistivity values of 12 different igneous rocks were measured on core samples using a resistivity meter in the laboratory. The resistivity tests were conducted on the samples fully saturated with brine (NaCl solution) and the uniaxial compressive strength (UCS), Brazilian tensile strength, density and porosity values of the samples were determined in the laboratory. The test results were evaluated using simple and multiple regression analysis. It was seen that the UCS and tensile strength values were linearly correlated with the electrical resistivity. The correlation coefficients are generally higher for the multiple regression models than that of the simple regression models. It was concluded that the UCS and tensile strength of igneous rocks can be estimated from electrical resistivity. However, the derived relations are purely empirical and they should be checked for other igneous rocks. The effect of rock types such as sedimentary and metamorphic rocks on the derived equations also needs to be investigated.

  17. ON RESIDUAL COMPRESSIVE STRENGTH PREDICTION OF COMPOSITE SANDWICH PANELS AFTER LOW-VELOCITY IMPACT DAMAGE

    Institute of Scientific and Technical Information of China (English)

    Xie Zonghong; Anthony J. Vizzini; Tang Qingru

    2006-01-01

    This paper introduces a nonlinear finite element analysis on damage propagation behavior of composite sandwich panels under in-plane uniaxial quasi-static compression after a low velocity impact. The major damage modes due to the impact, including the residual indentation on the impacted facesheet, the initially crushed core under the impacted area, and the delamination are incorporated into the model. A consequential core crushing mechanism is incorporated intothe analysis by using an element deactivation technique. Damage propagation behavior, which corresponds to those observed in sandwich compression after impact (SCAI) tests, has been successfully captured in the numerical simulation. The critical far field stress corresponding to the onset of damage propagation at specified critical locations near the damage zone are captured successfully. They show a good correlation with experimental data. These values can be used to effectively predict the residual compressive strength of low-velocity impact damaged composite sandwich panels.

  18. A Finite Element Analysis for Predicting the Residual Compressive Strength of Impact-Damaged Sandwich Panels

    Science.gov (United States)

    Ratcliffe, James G.; Jackson, Wade C.

    2008-01-01

    A simple analysis method has been developed for predicting the residual compressive strength of impact-damaged sandwich panels. The method is tailored for honeycomb core-based sandwich specimens that exhibit an indentation growth failure mode under axial compressive loading, which is driven largely by the crushing behavior of the core material. The analysis method is in the form of a finite element model, where the impact-damaged facesheet is represented using shell elements and the core material is represented using spring elements, aligned in the thickness direction of the core. The nonlinear crush response of the core material used in the analysis is based on data from flatwise compression tests. A comparison with a previous analysis method and some experimental data shows good agreement with results from this new approach.

  19. A Finite Element Analysis for Predicting the Residual Compression Strength of Impact-Damaged Sandwich Panels

    Science.gov (United States)

    Ratcliffe, James G.; Jackson, Wade C.

    2008-01-01

    A simple analysis method has been developed for predicting the residual compression strength of impact-damaged sandwich panels. The method is tailored for honeycomb core-based sandwich specimens that exhibit an indentation growth failure mode under axial compression loading, which is driven largely by the crushing behavior of the core material. The analysis method is in the form of a finite element model, where the impact-damaged facesheet is represented using shell elements and the core material is represented using spring elements, aligned in the thickness direction of the core. The nonlinear crush response of the core material used in the analysis is based on data from flatwise compression tests. A comparison with a previous analysis method and some experimental data shows good agreement with results from this new approach.

  20. Size effect of sandstone after high temperature under uniaxial compression

    Institute of Scientific and Technical Information of China (English)

    SU Hai-jian; JING Hong-wen; MAO Xian-biao; ZHAO Hong-hui; YIN Qian; WANG Chen

    2015-01-01

    Uniaxial compression tests on sandstone samples with five different sizes after high temperature processes were performed in order to investigate the size effect and its evolution. The test results show that the density, longitudinal wave velocity, peak strength, average modulus and secant modulus of sandstone decrease with the increase of temperature, however, peak strain increases gradually. With the increase of ratio of height to diameter, peak strength of sandstone decreases, which has an obvious size effect. A new theoretical model of size effect of sandstone material considering the influence of temperature is put forward, and with the increase of temperature, the size effect is more apparent. The threshold decreases gradually with the increase of temperature, and the deviations of the experimental values and the theoretical values are between 0.44% and 6.06%, which shows quite a credibility of the theoretical model.

  1. Prediction of Compressive Strength of Concrete Using Artificial Neural Network and Genetic Programming

    Directory of Open Access Journals (Sweden)

    Palika Chopra

    2016-01-01

    Full Text Available An effort has been made to develop concrete compressive strength prediction models with the help of two emerging data mining techniques, namely, Artificial Neural Networks (ANNs and Genetic Programming (GP. The data for analysis and model development was collected at 28-, 56-, and 91-day curing periods through experiments conducted in the laboratory under standard controlled conditions. The developed models have also been tested on in situ concrete data taken from literature. A comparison of the prediction results obtained using both the models is presented and it can be inferred that the ANN model with the training function Levenberg-Marquardt (LM for the prediction of concrete compressive strength is the best prediction tool.

  2. Use of triangular membership function for prediction of compressive strength of concrete containing nanosilica

    Directory of Open Access Journals (Sweden)

    Sakshi Gupta

    2015-12-01

    Full Text Available In this paper, application of fuzzy logic technique using triangular membership function for developing models for predicting compressive strength of concrete with partial replacement of cement with nanosilica has been carried out. For this, the data have been taken from various literatures and help in optimizing the constituents available and reducing cost and efforts in studying design to develop mixes by predefining suitable range for experimenting. The use of nanostructured materials in concrete can add many benefits that are directly related to the durability of various cementitious materials, besides the fact that it is possible to reduce the quantities of cement in the composite. Successful prediction by the model indicates that fuzzy logic could be a useful modelling tool for engineers and research scientists in the area of cement and concrete. Compressive strength values of concrete can be predicted in fuzzy logic models without attempting any experiments in a quite short period of time with tiny error rates.

  3. Analysis of the Flexure Behavior and Compressive Strength of Fly Ash Core Sandwiched Composite Material

    Directory of Open Access Journals (Sweden)

    Vijaykumar H.K

    2014-07-01

    Full Text Available In this paper, commercially available Fly Ash and Epoxy is used for the core material, woven glass fabric as reinforcing skin material, epoxy as matrix/adhesive materials used in this study for the construction of sandwich composite. Analysis is carried out on different proportions of epoxy and fly ash sandwiched composite material for determining the flexural strength and compressive strength, three different proportions of epoxy and fly ash used for the study. Those are 65%-35% (65% by weight fly ash and 35% by weight epoxy resin composite material, 60%-40% and 55%-45% composite material. 60%-40% composite material specimen shows better results in the entire test carried out i.e. Flexure and Compression. The complete experimental results are discussed and presented in this paper.

  4. Predicting Concrete Compressive Strength and Modulus of Rupture Using Different NDT Techniques

    Directory of Open Access Journals (Sweden)

    Wilfrido Martínez-Molina

    2014-01-01

    Full Text Available Quality tests applied to hydraulic concrete such as compressive, tension, and bending strength are used to guarantee proper characteristics of materials. All these assessments are performed by destructive tests (DTs. The trend is to carry out quality analysis using nondestructive tests (NDTs as has been widely used for decades. This paper proposes a framework for predicting concrete compressive strength and modulus of rupture by combining data from four NDTs: electrical resistivity, ultrasonic pulse velocity, resonant frequency, and hammer test rebound with DTs data. The model, determined from the multiple linear regression technique, produces accurate indicators predictions and categorizes the importance of each NDT estimate. However, the model is identified from all the possible linear combinations of the available NDT, and it was selected using a cross-validation technique. Furthermore, the generality of the model was assessed by comparing results from additional specimens fabricated afterwards.

  5. Increasing the compressive strength of portland cement concrete using flat glass powder

    Energy Technology Data Exchange (ETDEWEB)

    Miranda Junior, Edson Jansen Pedrosa de; Bezerra, Helton de Jesus Costa Leite; Politi, Flavio Salgado; Paiva, Antonio Ernandes Macedo, E-mail: edson.jansen@ifma.edu.br [Instituto Federal de Educacao, Ciencia e Tecnologia do Maranha (IFMA), Sao Luis, MA (Brazil). Dept. de Mecanica e Materiais

    2014-08-15

    This paper analyzes the compressive strength of Portland cement concrete in response to the incorporation of 5%, 10% and 20% of flat glass powder in place of sand, at w/c (water/cement) ratios of 0.50, 0.55 and 0.58. A statistical analysis of variance (ANOVA) was performed after 7, 14 and 28 days of curing. The compressive strength test results indicate that the concrete containing a w/c ratio of 0.50 can be used for structural applications, regardless of the waste glass content, as can that with a w/c ratio of 0.55 containing 20% of waste glass. We suggest that the use of flat glass powder in place of sand in the above mentioned percentages is feasible for the production of an environmentally appropriate and structurally applicable concrete. However, the concrete's fluidity and void content must be taken into account. (author)

  6. Comparative Investigation on Brazing Behavior, Compressive Strength, and Wear Properties of Multicrystalline CBN Abrasive Grains

    Directory of Open Access Journals (Sweden)

    Wen-Feng Ding

    2014-05-01

    Full Text Available In order to fabricate the abrasive wheels with good grain self-sharpening capacity, two types of multicrystalline CBN grains, that is, polycrystalline CBN (PCBN and binderless CBN (BCBN, were brazed using Cu-Sn-Ti alloy, respectively. Comparative investigation on the brazing interface, compressive strength, and wear properties of the different grains was carried out. Results obtained show that the PCBN grains have more intricate reaction, more complicated resultants, and thicker reaction layer than the BCBN counterparts under the identical brazing conditions. Though the average compressive strength of the PCBN grains is similar to that of BCBN ones, stronger self-sharpening action by virtue of the microfracture behavior takes place with BCBN grains during grinding. As a consequence, compared to the brazed PCBN wheels and the conventional monocrystalline CBN (MCBN ones, longer service life is obtained for the brazed BCBN wheels.

  7. Effect of Hybrid Fibers on the Mechanical Properties of High Strength Concrete

    Directory of Open Access Journals (Sweden)

    Hamid H. Hussein, Saeed K. Rejeb Hayder T. Abd

    2014-04-01

    Full Text Available In this study, high strength concrete of 75 MPa compressive strength was investigated. The experimental program was designed to study the effect of fibers and hybrid fibers (steel and polypropylene fibers on the fresh (workability and wet density and hardened properties (compressive strength, splitting strength, flexural strength and dry density of high strength concrete. Results show that decreases in slump flow of all concrete mixtures containing steel, polypropylene and hybrid fibers compared with control mix (0% fiber. Hybrid high strength concrete with steel and polypropylene fibers showed superior compressive, splitting, flexural strengths over the others concrete without or with single fibers content. The test results indicate that the maximum increase in compressive and flexural strengths are obtains with the hybridization ratio (70%steel + 30% polypropylene and were equal to 14.54% and 23.34% respectively, compared with the control mix. While, the maximum increase in splitting tensile strength with (100% steel fiber + 0 polypropylene is 21.19%. 

  8. Determination of composition of pozzolanic waste mixtures with optimized compressive strength

    Directory of Open Access Journals (Sweden)

    Nardi José Vidal

    2004-01-01

    Full Text Available The utilization of ceramic wastes with pozzolanic properties along with other compounds for obtaining new materials with cementating properties is an alternative for reducing the environmental pollution. The acceptance of these new products in the market demands minimal changes in mechanical properties according to its utilization. For a variable range of compositional intervals, attempts were made to establish limiting incorporation proportions that assure the achievement of minimum pre-established mechanical strength values in the final product. In this case minimum compressive strength value is 3,000 kPa. A simultaneous association of other properties is also possible.

  9. Prediction of concrete compressive strength considering humidity and temperature in the construction of nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Seung Hee; Jang, Kyung Pil [Department of Civil and Environmental Engineering, Myongji University, Yongin (Korea, Republic of); Bang, Jin-Wook [Department of Civil Engineering, Chungnam National University, Daejeon (Korea, Republic of); Lee, Jang Hwa [Structural Engineering Research Division, Korea Institute of Construction Technology (Korea, Republic of); Kim, Yun Yong, E-mail: yunkim@cnu.ac.kr [Structural Engineering Research Division, Korea Institute of Construction Technology (Korea, Republic of)

    2014-08-15

    Highlights: • Compressive strength tests for three concrete mixes were performed. • The parameters of the humidity-adjusted maturity function were determined. • Strength can be predicted considering temperature and relative humidity. - Abstract: This study proposes a method for predicting compressive strength developments in the early ages of concretes used in the construction of nuclear power plants. Three representative mixes with strengths of 6000 psi (41.4 MPa), 4500 psi (31.0 MPa), and 4000 psi (27.6 MPa) were selected and tested under various curing conditions; the temperature ranged from 10 to 40 °C, and the relative humidity from 40 to 100%. In order to consider not only the effect of the temperature but also that of humidity, an existing model, i.e. the humidity-adjusted maturity function, was adopted and the parameters used in the function were determined from the test results. A series of tests were also performed in the curing condition of a variable temperature and constant humidity, and a comparison between the measured and predicted strengths were made for the verification.

  10. The pore characteristics of geopolymer foam concrete and their impact on the compressive strength and modulus

    Directory of Open Access Journals (Sweden)

    Zuhua Zhang

    2016-08-01

    Full Text Available The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm is considered. This critical void model is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.

  11. The pore characteristics of geopolymer foam concrete and their impact on the compressive strength and modulus

    Science.gov (United States)

    Zhang, Zuhua; Wang, Hao

    2016-08-01

    The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA) and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm) is considered. This “critical void model” is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.

  12. Influence of Incorporating Fluoroapatite Nanobioceramic on the Compressive Strength and Bioactivity of Glass Ionomer Cement

    Directory of Open Access Journals (Sweden)

    Khaghani M

    2016-09-01

    Full Text Available Statement of Problem: In order to increase the performance of glass ionomer cement, it is reinforced with metal powders, short fibers, bioceramics and other materials. Fluoroapatite(Ca10(PO46F2 is found in dental enamel and is usually used in dental materials due to its good chemical and physical properties. Objectives: In this study, the effects of the addition of synthesized fluoroapatite nanoceramic on the compressive strength and bioactivity of glass ionomer cement were investigated. Materials and Methods: The synthesized fluoroapatite nanoceramic particles (~ 70 nm were incorporated into as-prepared glass ionomer powder and were characterized using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM. Moreover, the compressive strength values of the modified glass ionomer cements with 0, 1, 3 and 5 wt% of fluoroapatite were evaluated. Results: Results showed that glass ionomer cement containing 3 wt%fluoroapatite nanoparticles exhibited the highest compressive strength (102.6± 4 compared to the other groups, including control group. Furthermore, FTIR and SEM investigations indicated that after soaking the glass ionomer cement- 3 wt% fluoroapatite composite in the simulated body fluid solution, the intensity of O-H, P-O and C-O absorption bands increased as a result of the formation of apatite layer on the surface of the sample, and the rather flat and homogeneous surface of the cement became more porous and inhomogeneous. Conclusions: Addition of synthesized nano-fluoroapatite to as-prepared glass ionomer cement enhanced the compressive strength as well as nucleation of the calcium phosphate layer on the surface of the composite. This makes it a good candidate for dentistry and orthopedic applications.

  13. Prediction of Compressive Strength of Concrete Using Artificial Neural Network and Genetic Programming

    OpenAIRE

    Palika Chopra; Rajendra Kumar Sharma; Maneek Kumar

    2016-01-01

    An effort has been made to develop concrete compressive strength prediction models with the help of two emerging data mining techniques, namely, Artificial Neural Networks (ANNs) and Genetic Programming (GP). The data for analysis and model development was collected at 28-, 56-, and 91-day curing periods through experiments conducted in the laboratory under standard controlled conditions. The developed models have also been tested on in situ concrete data taken from literature. A comparison o...

  14. 锂渣复合粉煤灰高性能混凝土早期抗压强度影响因素的比较分析%The Comparative Analysis of Influence on the Early Compressive strength of lithium Slag Compound Fly Ash High Performance Concrete

    Institute of Scientific and Technical Information of China (English)

    周海雷; 杨恒阳; 努尔开力·依孜特罗甫; 侍克斌

    2012-01-01

    Lithium slag compound fly ash high performance concrete was made by the orthogonal experiment design method, the preparation of the use of poor analysis and variance analysis method to analyze the impact that the water-binder ratio, lithium slag mix content and the fly ash for lithium slag compound fly ash of high performance concrete compressive strength of the early. Lithium slag on lithium slag compound fly ash high performance concrete compressive strength has significance effects Dmng early. Dmng analysis of the poor, poor relative difference degree was introduced the concept.%运用正交试验设计的方法配制锂渣复合粉煤灰高性能混凝土,运用极差分析和方差分析的方法分析了水胶比、锂渣掺量和粉煤灰掺量对锂渣复合粉煤灰高性能混凝土的早期抗压强度的影响,得出锂渣较粉煤灰对锂渣复合粉煤灰高性能混凝土早期抗压强度影响显著.在进行极差分析时,引入了极差相对差异度这一概念.

  15. Effect of chlorhexidine gluconate on porosity and compressive strength of a glass ionomer cement

    Directory of Open Access Journals (Sweden)

    Luana Mafra MARTI

    Full Text Available INTRODUCTION:For presenting wide antibacterial activity, chlorhexidine (CHX has been extensively used in dentistry and can be easily incorporated into the glass ionomer cement (GIC and consequently released into the oral cavity.AIM: The aim of this study was porosity and compression strength of a GIC, that was added to different concentrations of CHX.MATERIAL AND METHOD: Specimens were prepared with GIC (Ketac Molar Esaymix and divided into 4 groups according to the concentration of CHX: control, 0.5% and 1% and 2% (n = 10. For analysis of pores specimens were fractured with the aid of hammer and chisel surgical, so that the fracture was performed in the center of the specimens, dividing it in half and images were obtained from a scanning electron microscope (SEM analyzed in Image J software. The compressive strength test was conducted in a mechanical testing machine (EMIC - Equipment and Testing Systems Ltd., Joseph of the Pines, PR, Brazil. Statistical analysis was performed by ANOVA, Tukey test. Significance level of 5%.RESULT: No statistically significant changes between the study groups was observed both for the number of pores as well as for the compressive strength.CONCLUSION: The use of GIC associated with CHX gluconate 1% and 2% is the best option to be used in dental practice.

  16. Experimental study of tensile strength of pharmaceutical tablets: effect of the diluent nature and compression pressure

    Science.gov (United States)

    Juban, Audrey; Briançon, Stéphanie; Puel, François; Hoc, Thierry; Nouguier-Lehon, Cécile

    2017-06-01

    In the pharmaceutical field, tablets are the most common dosage form for oral administration in the world. Among different manufacturing processes, direct compression is widely used because of its economics interest and it is a process which avoids the steps of wet granulation and drying processes. Tablets are composed of at least two ingredients: an active pharmaceutical ingredient (API) which is mixed with a diluent. The nature of the powders and the processing conditions are crucial for the properties of the blend and, consequently, strongly influence the mechanical characteristics of tablets. Moreover, tablets have to present a suitable mechanical strength to avoid crumbling or breaking when handling, while ensuring an appropriate disintegration after administration. Accordingly, this mechanical property is an essential parameter to consider. Experimental results showed that proportion of the diluent, fragmentary (DCPA) or plastic (MCC), had a large influence on the tensile strength evolution with API content as well as the compression load applied during tableting process. From these results a model was developed in order to predict the tensile strength of binary tablets by knowing the compression pressure. The validity of this model was demonstrated for the two studied systems and a comparison was made with two existing models.

  17. Mesoscopic Numerical Computation of Compressive Strength and Damage Mechanism of Rubber Concrete

    Directory of Open Access Journals (Sweden)

    Z. H. Xie

    2015-01-01

    Full Text Available Evaluations of both macroscopic and mesoscopic strengths of materials have been the topic of a great deal of recent research. This paper presents the results of a study, based on the Walraven equation of the production of a mesoscopic random aggregate structure containing various rubber contents and aggregate sizes. On a mesoscopic scale, the damage mechanism in the rubber concrete and the effects of the rubber content and aggregate-mortar interface on the rubber concrete’s compressive resistance property were studied. The results indicate that the random aggregate structural model very closely approximates the experimental results in terms of the fracture distribution and damage characteristics under uniaxial compression. The aggregate-mortar interface mechanical properties have a substantial impact on the test sample’s strength and fracture distribution. As the rubber content increases, the compressive strength and elastic modulus of the test sample decrease proportionally. This paper presents graphics of the entire process from fracture propagation to structural failure of the test piece by means of the mesoscopic finite-element method, which provides a theoretical reference for studying the damage mechanism in rubber concrete and performing parametric calculations.

  18. Experimental study of tensile strength of pharmaceutical tablets: effect of the diluent nature and compression pressure

    Directory of Open Access Journals (Sweden)

    Juban Audrey

    2017-01-01

    Full Text Available In the pharmaceutical field, tablets are the most common dosage form for oral administration in the world. Among different manufacturing processes, direct compression is widely used because of its economics interest and it is a process which avoids the steps of wet granulation and drying processes. Tablets are composed of at least two ingredients: an active pharmaceutical ingredient (API which is mixed with a diluent. The nature of the powders and the processing conditions are crucial for the properties of the blend and, consequently, strongly influence the mechanical characteristics of tablets. Moreover, tablets have to present a suitable mechanical strength to avoid crumbling or breaking when handling, while ensuring an appropriate disintegration after administration. Accordingly, this mechanical property is an essential parameter to consider. Experimental results showed that proportion of the diluent, fragmentary (DCPA or plastic (MCC, had a large influence on the tensile strength evolution with API content as well as the compression load applied during tableting process. From these results a model was developed in order to predict the tensile strength of binary tablets by knowing the compression pressure. The validity of this model was demonstrated for the two studied systems and a comparison was made with two existing models.

  19. Determination of dynamic shear strength of 2024 aluminum alloy under shock compression

    Directory of Open Access Journals (Sweden)

    H. S. Zhang

    2016-04-01

    Full Text Available A series of plate impact shock-reshock and shock-release experiments were conducted by using an one-stage light gas gun to determine the critical shear strength of the 2024 aluminum alloy under shock compression levels ranging from 0.66 to 3.05 GPa in the present study. In the experiments, a dual flyer plate assembly, i.e., the 2024 aluminum alloy flyer backed either by a brass plate or a PMMA plate, was utilized to produce reshock or release wave. The stress profiles of uniaxial plane strain wave propagation in the 2024 aluminum alloy sample under different pre-compressed states were measured by the embedded stress gauges. The stress-strain data at corresponding states were then calculated by a Lagrangian analysis method named as path line method. The critical shear strengths at different stress levels were finally obtained by self-consistent method. The results show that, at the low shock compression level (0.66 to 3.05 GPa, the critical shear strength of the 2024 aluminum alloy cannot be ignored and increases with the increasing longitudinal stress, which may be attributed to rate-dependence and/or pressure dependent yield behavior of the 2024 aluminum alloy.

  20. Evaluation of strength-enhancing factors of a ductile binder in direct compression of sodium bicarbonate and calcium carbonate powders.

    Science.gov (United States)

    Mattsson, S; Nyström, C

    2000-03-01

    This study evaluated the effectiveness of a ductile binder in direct compression of sodium bicarbonate and calcium carbonate powders. Properties associated with both the binder and the compound were studied. The addition of binder materials, such as polyethylene glycols (PEGs) of differing molecular weights or microcrystalline cellulose, generally resulted in an increase in the axial tensile strength of the corresponding compacts. The increase in tablet strength was generally greater with the PEGs than with microcrystalline cellulose. The results indicate that the improvement in tablet strength caused by the binder is dependent on properties of both the binder and the compound. By utilising different methods it was established that the fracture during tablet strength testing mainly occurred around the compound particles. As a consequence of this, it appears that the ability of the binder to fill the voids between the compound particles is a determinative factor for increasing tablet strength. The binder appeared to have less effect when added to compounds that fragmented during compaction. Characteristics of the binder resulting in the greatest decrease in porosity, and thus the greatest increase in the tensile strength of the compound, included a high degree of plastic deformation with a limited elastic component and a small particle size. Obviously, the amount of binder added to the mixture also affected the results.

  1. High-quality lossy compression: current and future trends

    Science.gov (United States)

    McLaughlin, Steven W.

    1995-01-01

    This paper is concerned with current and future trends in the lossy compression of real sources such as imagery, video, speech and music. We put all lossy compression schemes into common framework where each can be characterized in terms of three well-defined advantages: cell shape, region shape and memory advantages. We concentrate on image compression and discuss how new entropy constrained trellis-based compressors achieve cell- shape, region-shape and memory gain resulting in high fidelity and high compression.

  2. Behavior of high strength concrete columns under eccentric loads

    Directory of Open Access Journals (Sweden)

    Hany A. Kottb

    2015-04-01

    Full Text Available In recent decades, high strength concrete (HSC has been widely accepted by designers and contractors to be used in concrete structures, especially in high compressive stress elements. The research aims to study the behavior of high strength concrete columns under eccentric compression using experimental and analytical programs. The research is divided into two main parts; the first part is an experimental investigation for ten square columns tested at the Cairo University Concrete Research Laboratory. The main studied parameters were eccentricity of the applied load, column slenderness ratio; and ratios of longitudinal and transverse reinforcement. The second part is analytical analysis using nonlinear finite element program ANSYS11 on nineteen columns (ten tested square columns and nine rectangular section columns to study the effect of the previous parameters on the column ultimate load, mid-height displacement, and column cracking patterns. The analyzed columns revealed a good agreement with the experimental results with an average difference of 16% and 17% for column ultimate load and mid-height displacement respectively. Results showed an excellent agreement for cracking patterns. Predictions of columns capacities using the interaction diagrams based on ACI 318-08 stress block parameters indicated a safe design procedure of HSC columns under eccentric compression, with ACI 318-08 being more conservative for moderate reinforced HSC columns.

  3. Modeling of Hydration, Compressive Strength, and Carbonation of Portland-Limestone Cement (PLC) Concrete.

    Science.gov (United States)

    Wang, Xiao-Yong

    2017-01-26

    Limestone is widely used in the construction industry to produce Portland limestone cement (PLC) concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel-space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.

  4. Modeling of Hydration, Compressive Strength, and Carbonation of Portland-Limestone Cement (PLC Concrete

    Directory of Open Access Journals (Sweden)

    Xiao-Yong Wang

    2017-01-01

    Full Text Available Limestone is widely used in the construction industry to produce Portland limestone cement (PLC concrete. Systematic evaluations of hydration kinetics, compressive strength development, and carbonation resistance are crucial for the rational use of limestone. This study presents a hydration-based model for evaluating the influences of limestone on the strength and carbonation of concrete. First, the hydration model analyzes the dilution effect and the nucleation effect of limestone during the hydration of cement. The degree of cement hydration is calculated by considering concrete mixing proportions, binder properties, and curing conditions. Second, by using the gel–space ratio, the compressive strength of PLC concrete is evaluated. The interactions among water-to-binder ratio, limestone replacement ratio, and strength development are highlighted. Third, the carbonate material contents and porosity are calculated from the hydration model and are used as input parameters for the carbonation model. By considering concrete microstructures and environmental conditions, the carbon dioxide diffusivity and carbonation depth of PLC concrete are evaluated. The proposed model has been determined to be valid for concrete with various water-to-binder ratios, limestone contents, and curing periods.

  5. Experimental Study on the Compressive Strength of Big Mobility Concrete with Nondestructive Testing Method

    Directory of Open Access Journals (Sweden)

    Huai-Shuai Shang

    2012-01-01

    Full Text Available An experimental study of C20, C25, C30, C40, and C50 big mobility concrete cubes that came from laboratory and construction site was completed. Nondestructive testing (NDT was carried out using impact rebound hammer (IRH techniques to establish a correlation between the compressive strengths and the rebound number. The local curve for measuring strength of the regression method is set up and its superiority is proved. The rebound method presented is simple, quick, and reliable and covers wide ranges of concrete strengths. The rebound method can be easily applied to concrete specimens as well as existing concrete structures. The final results were compared with previous ones from the literature and also with actual results obtained from samples extracted from existing structures.

  6. Influence of ultrasonic setting on compressive and diametral tensile strengths of glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Terezinha Jesus Esteves Barata

    2008-03-01

    Full Text Available The aim of this study was to assess the influence of ultrasonic wave propagation on the compressive (CS and diametral tensile (DTS strengths of glass ionomer cements (GICs. Three variables were evaluated: conventional GICs, ultrasonic excitation and storage time (1 hour, 24 hours and 7 days. Bovine teeth molds were used for simulating a clinical ultrasonic excitation. The data were submitted to three-way ANOVA and Tukey tests (P < 0.05. All the tested conventional GICs presented an increase in strength from 1 hour to 7 days for CS and DTS. Ultrasonic excitation resulted in a statistically significant increase in the CS, but showed no statistically significant difference in the DTS. Regardless the GICs tested the increase in strength was maturation time-dependent for all groups.

  7. HRB500级高强钢筋偏心受压截面对称配筋设计研究%Study of cross-section symmetrical reinforcement design reinforced with HRB500 high-strength steel bars under eccentric compression

    Institute of Scientific and Technical Information of China (English)

    曾亮; 华建民; 兰定筠; 袁渊

    2013-01-01

    通过对新GB 50010-2010《混凝土结构设计规范》中增加的HRB500级高强钢筋用于偏心受压构件时的截面对称配筋进行研究,得到HRB500级高强钢筋偏心受压构件大小偏心受压的判别条件,以及对应的截面配筋计算方法;同时,对HRB500级高强钢筋对应的Nu-Mu相关曲线进行讨论.本文研究结论为高强钢筋偏心受压构件对称配筋截面设计提供了具体判别条件和计算方法.%Through the study of eccentric compression cross-section symmetrical reinforcement design reinforced with HRB500 highstrength steel bars,which adds into the new Code for the Design of Concrete Structures GB50010-2010 recently,it gets the criterion for large and small eccentricity of eccentric compression member,and the corresponding cross-section reinforcement calculation method.Furthermore,it discusses the Nu-Mu interaction curve of HRB500 high-strength steel bars.The conclusion will provide specific criterion and calculation method for eccentric compression cross-section symmetrical reinforcement design reinforced with high-strength steel bars.

  8. MECHANICAL STRENGTH OF HIGHLY POROUS CERAMICS

    NARCIS (Netherlands)

    VANDENBORN, IC; SANTEN, A; HOEKSTRA, HD; DEHOSSON, JTM; Born, I.C. van den

    1991-01-01

    This paper reports on the mechanical strength of highly porous ceramics in terms of the Weibull and Duxbury-Leath distributions. More than 1000 side-crushing strength tests on silica-catalyst carriers of various particle sizes have been performed in series. Within a series, preparation conditions we

  9. High strain rate compression testing of glass fibre reinforced polypropylene

    Directory of Open Access Journals (Sweden)

    Cloete T.J.

    2012-08-01

    Full Text Available This paper details an investigation of the high strain rate compression testing of GFPP with the Split Hopkinson Pressure Bar (SHPB in the through-thickness and in-plane directions. GFPP posed challenges to SHPB testing as it fails at relatively high stresses, while having relatively low moduli and hence mechanical impedance. The modifications to specimen geometry and incident pulse shaping in order to gather valid test results, where specimen equilibrium was achieved for SHPB tests on GFPP are presented. In addition to conventional SHPB tests to failure, SHPB experiments were designed to achieve specimen equilibration at small strains, which permitted the capture of high strain rate elastic modulus data. The strain rate dependency of GFPP’s failure strengths in the in-plane and through-thickness direction is modelled using a logarithmic law.

  10. High-Hot-Strength Ceramic Fibers

    Science.gov (United States)

    Sayir, Ali; Matson, Lawrence E.

    1994-01-01

    Continuous fibers consisting of laminae of alumina and yttrium aluminum garnet offer exceptionally high strength, resistance to creep, and chemical stability at high temperatures. These fibers exceed tensile strength of sapphire fibers. Leading candidates for reinforcement of intermetallic-matrix composites in exhaust nozzles of developmental high-speed civil transport aircraft engines. Other applications are in aerospace, automotive, chemical-process, and power-generation industries.

  11. High Strain Rate Compression Testing of Ceramics and Ceramic Composites.

    Energy Technology Data Exchange (ETDEWEB)

    Blumenthal, W. R. (William R.)

    2005-01-01

    The compressive deformation and failure behavior of ceramics and ceramic-metal composites for armor applications has been studied as a function of strain rate at Los Alamos National Laboratory since the late 1980s. High strain rate ({approx}10{sup 3} s{sup -1}) uniaxial compression loading can be achieved using the Kolsky-split-Hopkinson pressure bar (SHPB) technique, but special methods must be used to obtain valid strength results. This paper reviews these methods and the limitations of the Kolsky-SHPB technique for this class of materials. The Kolsky-split-Hopkinson pressure bar (Kolsky-SHPB) technique was originally developed to characterize the mechanical behavior of ductile materials such as metals and polymers where the results can be used to develop strain-rate and temperature-dependent constitutive behavior models that empirically describe macroscopic plastic flow. The flow behavior of metals and polymers is generally controlled by thermally-activated and rate-dependent dislocation motion or polymer chain motion in response to shear stresses. Conversely, the macroscopic mechanical behavior of dense, brittle, ceramic-based materials is dominated by elastic deformation terminated by rapid failure associated with the propagation of defects in the material in response to resolved tensile stresses. This behavior is usually characterized by a distribution of macroscopically measured failure strengths and strains. The basis for any strain-rate dependence observed in the failure strength must originate from rate-dependence in the damage and fracture process, since uniform, uniaxial elastic behavior is rate-independent (e.g. inertial effects on crack growth). The study of microscopic damage and fracture processes and their rate-dependence under dynamic loading conditions is a difficult experimental challenge that is not addressed in this paper. The purpose of this paper is to review the methods that have been developed at the Los Alamos National Laboratory to

  12. Confined Tension and Triaxial Extension Tests on Eglin High-Strength Concrete

    Science.gov (United States)

    2014-10-17

    AFRL-RW-EG-TR-2014-120 Confined Tension and Triaxial Extension Tests on Eglin High-Strength Concrete Lance...EXTENSION TESTS ON EGLIN HIGH-STRENGTH CONCRETE FA8651-12-D-0309, Task 005 N/A 2502 9210 W0DT (1) Lance Besaw, Applied Research Associates, Inc. (2...models. All concretes exhibit higher strength in compression than in tension, therefore it is critical to understand the tensile properties of such

  13. A prediction model for uniaxial compressive strength of deteriorated pyroclastic rocks due to freeze-thaw cycle

    Science.gov (United States)

    İnce, İsmail; Fener, Mustafa

    2016-08-01

    Either directly or indirectly, building stone is exposed to diverse atmospheric interactions depending on the seasonal conditions. Due to those interactions, objects of historic and cultural heritage, as well as modern buildings, partially or completely deteriorate. Among processes involved in rock deterioration, the freeze-thaw (F-T) cycle is one of the most important. Even though pyroclastic rocks have been used as building stone worldwide due to their easy workability, they are the building stone most affected by the F-T cycle. A historical region in Central Anatolia, Turkey, Cappadoia encompasses exceptional natural wonders characterized by fairy chimneys and unique historical and cultural heritage. Human-created caves, places of worship and houses have been dug into the pyroclastic rocks, which have in turn been used in architectural construction as building stone. Using 10 pyroclastic rock samples collected from Cappadocia, we determined the rock's index-mechanical properties to develop a statistical model for estimating percentage loss of uniaxial compressive strength a critical parameter of F-T cycle's important value. We used dry density (ρd), ultrasonic velocity (Vp), point load strengths (IS(50)), and slake-durability test indexes (Id4) values of unweathered rocks in our model, which is highly reliable (R2 = 0.84) for predetermination of percentage loss of uniaxial compressive strengths of pyroclastic rocks without requiring any F-T tests.

  14. Influence of variables on the consolidation and unconfined compressive strength of crushed salt: Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifle, T.W.; Senseny, P.E.; Mellegard, K.D.

    1987-01-01

    Eight hydrostatic compression creep tests were performed on crushed salt specimens fabricated from Avery Island dome salt. Following the creep test, each specimen was tested in unconfined compression. The experiments were performed to assess the influence of the following four variables on the consolidation and unconfined strength of crushed salt: grain size distribution, temperature, time, and moisture content. The experiment design comprised a half-fraction factorial matrix at two levels. The levels of each variable investigated were grain size distribution, uniform-graded and well-graded (coefficient of uniformity of 1 and 8); temperature 25/sup 0/C and 100/sup 0/C; time, 3.5 x 10/sup 3/s and 950 x 10/sup 3/s (approximately 60 minutes and 11 days, respectively); and moisture content, dry and wet (85% relative humidity for 24 hours). The hydrostatic creep stress was 10 MPa. The unconfined compression tests were performed at an axial strain rate of 1 x 10/sup -5/s/sup -1/. Results show that the variables time and moisture content have the greatest influence on creep consolidation, while grain size distribution and, to a somewhat lesser degree, temperature have the greatest influence on total consolidation. Time and moisture content and the confounded two-factor interactions between either grain size distribution and time or temperature and moisture content have the greatest influence on unconfined strength. 7 refs., 7 figs., 11 tabs.

  15. Correlation Between P-wave Velocity and Strength Index for Shale to Predict Uniaxial Compressive Strength Value

    Directory of Open Access Journals (Sweden)

    Awang H.

    2017-01-01

    Full Text Available Seismic refraction survey is a non destructive method used in site investigation to identify the seismic velocity subsurface strata. Although it is widely known, the reliability of the result is still doubtable for some reason as well as due to an engineer’s ignorant, which insist on using conventional method rather than new advanced method causing the lack of usage in geophysical method for testing. This study aims to produce a correlation between P-wave velocity value and point load strength index value for shale. Both field and laboratory tests were carried out. In order to obtain the P-wave value, seismic refraction method was conducted as a field test at Precint 4, Putrajaya, Malaysia to achieve the Pwave velocity value of the shale bed. Ten samples of shale were collected from the field and laboratory tests were conducted. The tests are divided into three sections, namely non-destructive laboratory test, physical properties test and mechanical properties test. Ultrasonic Velocity Test via PUNDIT test was conducted as non-destructive laboratory test to acknowledge the P-wave velocity value in laboratory. Both field and laboratory P-wave velocity value were then compared and the result delivers are reliable due to it is within the range. For physical properties test, the rock density and porosity were acknowledged. Meanwhile, Point Load Test was conducted as mechanical properties. Correlation for both Pwave velocity value and point load strength value were achieved via producing an empirical relationship as the end result. Prediction of uniaxial compressive strength (UCS value was made via converting the point load strength value to UCS value using a correlation. By acknowledging this empirical relationship, it shows that geophysical methods are able to produce a reliable result. Hence more and widely used of geophysical method will be profound in the future.

  16. Aging and Curing Temperature Effects on Compressive Strength of Mortar Containing Lime Stone Quarry Dust and Industrial Granite Sludge

    Directory of Open Access Journals (Sweden)

    Muhammad Nasir Amin

    2017-06-01

    Full Text Available In this study, the researchers investigated the potential use of locally available waste materials from the lime stone quarry and the granite industry as a partial replacement of cement. Quarry sites and granite industry in the eastern province of Saudi Arabia produces tons of powder wastes in the form of quarry dust (QD and granite sludge (GS, respectively, causing serious environmental problems along with frequent dust storms in the area. According to ASTM C109, identical 50-mm3 specimens were cast throughout this study to evaluate the compressive strength development of mortars (7, 28 and 91 days containing these waste materials. Experimental variables included different percentage replacement of cement with waste materials (GS, QD, fineness of GS, various curing temperatures (20, 40 and 60 °C as local normal and hot environmental temperatures and curing moisture (continuously moist and partially moist followed by air curing. Finally, the results of mortar containing waste materials were compared to corresponding results of control mortar (CM and mortar containing fly ash (FA. The test results indicated that under normal curing (20 °C, moist cured, the compressive strength of mortar containing the different percentage of waste materials (QD, GS, FA and their combinations remained lower than that of CM at all ages. However, the compressive strength of mortar containing waste materials slightly increased with increased fineness of GS and significantly increased under high curing temperatures. It was recommended that more fineness of GS be achieved to use its high percentage replacement with cement (30% or more incorporating local environmental conditions.

  17. Aging and Curing Temperature Effects on Compressive Strength of Mortar Containing Lime Stone Quarry Dust and Industrial Granite Sludge.

    Science.gov (United States)

    Amin, Muhammad Nasir; Khan, Kaffayatullah; Saleem, Muhammad Umair; Khurram, Nauman; Niazi, Muhammad Umar Khan

    2017-06-11

    In this study, the researchers investigated the potential use of locally available waste materials from the lime stone quarry and the granite industry as a partial replacement of cement. Quarry sites and granite industry in the eastern province of Saudi Arabia produces tons of powder wastes in the form of quarry dust (QD) and granite sludge (GS), respectively, causing serious environmental problems along with frequent dust storms in the area. According to ASTM C109, identical 50-mm3 specimens were cast throughout this study to evaluate the compressive strength development of mortars (7, 28 and 91 days) containing these waste materials. Experimental variables included different percentage replacement of cement with waste materials (GS, QD), fineness of GS, various curing temperatures (20, 40 and 60 °C as local normal and hot environmental temperatures) and curing moisture (continuously moist and partially moist followed by air curing). Finally, the results of mortar containing waste materials were compared to corresponding results of control mortar (CM) and mortar containing fly ash (FA). The test results indicated that under normal curing (20 °C, moist cured), the compressive strength of mortar containing the different percentage of waste materials (QD, GS, FA and their combinations) remained lower than that of CM at all ages. However, the compressive strength of mortar containing waste materials slightly increased with increased fineness of GS and significantly increased under high curing temperatures. It was recommended that more fineness of GS be achieved to use its high percentage replacement with cement (30% or more) incorporating local environmental conditions.

  18. The influence of dicarboxylic acids: Oxalic acid and tartaric acid on the compressive strength of glass ionomer cements

    Science.gov (United States)

    Permana, Ahmadi Jaya; Setyawati, Harsasi; Hamami, Murwani, Irmina Kris

    2016-03-01

    Glass ionomer cement (GIC) has limitation on the mechanical properties especially compressive strength. The change of compressive strength of GIC by adding oxalic acid and tartaric acid has been investigated. Oxalic acid and tartaric acid was added to the liquid components at concentrations of 0 - 15% (w/w). Powder component of GIC was made from optimum experimental powder glass SiO2-Al2O3-CaF2. GIC was characterized by compressive strength test, SEM-EDX and FTIR. The addition of tartaric acid to GIC has greater improvement than addition of oxalic acid. The addition of tartaric acid at 10 % (w/w) to GIC has greatest value of compressive strength.

  19. The Effect of Alkaline Activator Ratio on the Compressive Strength of Fly Ash-Based Geopolymer Paste

    Science.gov (United States)

    Lăzărescu, A. V.; Szilagyi, H.; Baeră, C.; Ioani, A.

    2017-06-01

    Alkaline activation of fly ash is a particular procedure in which ash resulting from a power plant combined with a specific alkaline activator creates a solid material when dried at a certain temperature. In order to obtain desirable compressive strengths, the mix design of fly ash based geopolymer pastes should be explored comprehensively. To determine the preliminary compressive strength for fly ash based geopolymer paste using Romanian material source, various ratios of Na2SiO3 solution/ NaOH solution were produced, keeping the fly ash/alkaline activator ratio constant. All the mixes were then cured at 70 °C for 24 hours and tested at 2 and 7 days, respectively. The aim of this paper is to present the preliminary compressive strength results for producing fly ash based geopolymer paste using Romanian material sources, the effect of alkaline activators ratio on the compressive strength and studying the directions for future research.

  20. Compressive Strength of EN AC-44200 Based Composite Materials Strengthened with α-Al2O3 Particles

    National Research Council Canada - National Science Library

    A. Kurzawa; J. W. Kaczmar

    2017-01-01

    The paper presents results of compressive strength investigations of EN AC-44200 based aluminum alloy composite materials reinforced with aluminum oxide particles at ambient and at temperatures of 100, 200 and 250°C...

  1. The Value Compressive Strength and Split Tensile Strength on Concrete Mixture With Expanded Polystyrene Coated by Surfactant Span 80 as a Partial Substitution of Fine Aggregate

    Directory of Open Access Journals (Sweden)

    Hidayat Irpan

    2014-03-01

    Full Text Available The value of the density normal concrete which ranges between 2200–2400 kg/m3. Therefore the use of Expanded Polystyrene (EPS as a subitute to fine aggregate can reduce the density of concrete. The purpose this research is to reduce the density of normal concrete but increase compressive strength of EPS concrete, with use surfactant as coating for the EPS. Variables of substitution percentage of EPS and EPS coated by surfactant are 5%,10%,15%,20%,25%. Method of concrete mix design based on SNI 03-2834-2000 “Tata Cara Pembuatan Rencana Campuran Beton Normal (Provisions for Proportioning Normal Concrete Mixture”. The result of testing, every increase percentage of EPS substitution will decrease the compressive strength around 1,74 MPa and decrease density 34,03 kg/m3. Using Surfactant as coating of EPS , compressive strength increase from the EPS’s compressive strength. Average of increasing compressive strength 0,19 MPa and increase the density 20,03 kg/m3,average decrease of the tensile split strength EPS coated surfaktan is 0,84 MPa.

  2. The Value Compressive Strength and Split Tensile Strength on Concrete Mixture With Expanded Polystyrene Coated by Surfactant Span 80 as a Partial Substitution of Fine Aggregate

    Science.gov (United States)

    Hidayat, Irpan; Siauwantara, Alice

    2014-03-01

    The value of the density normal concrete which ranges between 2200-2400 kg/m3. Therefore the use of Expanded Polystyrene (EPS) as a subitute to fine aggregate can reduce the density of concrete. The purpose this research is to reduce the density of normal concrete but increase compressive strength of EPS concrete, with use surfactant as coating for the EPS. Variables of substitution percentage of EPS and EPS coated by surfactant are 5%,10%,15%,20%,25%. Method of concrete mix design based on SNI 03-2834-2000 "Tata Cara Pembuatan Rencana Campuran Beton Normal (Provisions for Proportioning Normal Concrete Mixture)". The result of testing, every increase percentage of EPS substitution will decrease the compressive strength around 1,74 MPa and decrease density 34,03 kg/m3. Using Surfactant as coating of EPS , compressive strength increase from the EPS's compressive strength. Average of increasing compressive strength 0,19 MPa and increase the density 20,03 kg/m3,average decrease of the tensile split strength EPS coated surfaktan is 0,84 MPa.

  3. Compressive Strength Properties of Natural Gas Hydrate Pellet by Continuous Extrusion from a Twin-Roll System

    OpenAIRE

    Yun-Hoo Lee; Bong-Hwan Koh; Heung Soo Kim; Myung Ho Song

    2013-01-01

    This study investigates the compressive strength of natural gas hydrate (NGH) pellet strip extruded from die holes of a twin-roll press for continuous pelletizing (TPCP). The lab-scale TPCP was newly developed, where NGH powder was continuously fed and extruded into strip-type pellet between twin rolls. The system was specifically designed for future expansion towards mass production of solid form NGH. It is shown that the compressive strength of NGH pellet strip heavily depends on parameters...

  4. Effect Of Coir Fibres On The Compaction And Unconfined Compressive Strength Of Bentonite-Lime-Gypsum Mixture

    Directory of Open Access Journals (Sweden)

    Tilak B. Vidya

    2015-06-01

    Full Text Available This paper presents the effect of coir fibres on the compaction and unconfined compressive strength of a bentonite-lime-gypsum mixture. The coir fiber content varied from 0.5 to 2 %. The results indicated that the dry unit weight and the optimum moisture content of a bentonite – lime mix increased with the addition of gypsum. The unconfined compressive strength of the bentonite increased with the increase in the lime content up to 8 %. Beyond 8 %, the unconfined compressive strength decreased. The dry unit weight of the reference mix decreased, and the optimum moisture content increased with the addition of coir fibre. The unconfined compressive strength of the bentonite + 8 % lime mix increased up to 4 % with the gypsum. Beyond 4 %, the unconfined compressive strength decreased. The unconfined compressive strength of the reference mix increased with the addition of coir fibre up to a fibre content of 1.5 %. The unconfined compressive strength of the reference mix-coir fibre composite was less in comparison to the reference mix. The unconfined compressive strength of the bentonite increased with the addition of lime and gypsum and with the increase in the curing period. The improvement in the post-peak region was better for the reference mix with reinforced coir fibres as compared to the unreinforced reference mix. The improved post-peak behaviour of the bentonite-lime-gypsum-coir fibre mixture could boost the construction of temporary roads on such problematic soils. Further, its use will also provide an environmental motivation for providing a means of consuming large quantities of coir fibres.

  5. Compressive strength and the effect of duration after photo-activation among dual-cure bulk fill composite core materials.

    Science.gov (United States)

    Alkhudhairy, Fahad; Vohra, Fahim

    2016-01-01

    To assess compressive strength and effect of duration after photoactivation on the compressive strength of different dual cure bulk fill composites. Seventy-two disc shaped (4x10mm) specimens were prepared from three dual cure bulk fill materials, ZirconCore (ZC) (n=24), MulticCore Flow (MC) (n=24) and Luxacore Dual (LC) (n=24). Half of the specimens in each material were tested for failure loads after one hour [MC1 (n=12), LC1 (n=12) & ZC1 (n=12)] and the other half in 7 days [MC7 (n=12), LC7 (n=12), ZC7 (n=12)] from photo-polymerization using the universal testing machine at a cross-head speed of 0.5 cm/minutes. Compressive strength was calculated using the formula UCS=4f/πd(2). Compressive strengths among different groups were compared using analysis of variance (ANOVA) and Tukey's multiple comparisons test. Maximum and minimum compressive strengths were observed in ZC7 (344.14±19.22) and LC1 (202.80±15.52) groups. Specimens in LC1 [202.80 (15.52)] showed significantly lower compressive strength as compared to MC1 [287.06 (15.03)] (pstrengths compared to LC7 [324.56 (19.47)] and MC7 [315.26 (12.36)]. Compressive strengths among all three materials were significantly higher (pstrength compared to MC and LC. Increasing the post photo-activation duration (from one hour to 7 days) significantly improves the compressive strengths of dual cure bulk fill material.

  6. Zeolite-silver-zinc nanoparticles: Biocompatibility and their effect on the compressive strength of mineral trioxide aggregate

    Science.gov (United States)

    Samiei, Mohammad; Ghasemi, Negin; Asl-Aminabadi, Naser; Divband, Baharak; Golparvar-Dashti, Yasamin

    2017-01-01

    Background This study was carried out to evaluate the biocompatibility of zeolite-silver-zinc (Ze-Ag-Zn) nanoparticles and their effect on the compressive strength of Mineral Trioxide Aggregate (MTA). Material and Methods Biocompatibility was evaluated by an MTT assay on the pulmonary adenocarcinoma cells with 0.05, 0.1, 0.25, 0.5, 1 and 5 mg/mL concentrations of Ze-Ag-Zn. For compressive strength test, four groups containing 15 stainless-steel cylinders with an internal diameter of 4 and a height of 6 mm were prepared and MTA (groups 1 and 2) or MTA + 2% Ze-Ag-Zn (groups 3 and 4) were placed in the cylinders. The compressive strength was evaluated using a universal testing machine 4 days after mixing in groups 1 and 3, and 21 days after mixing in groups 2 and 4. Results There was no significant difference between cytotoxicity of different concentrations. The highest (52.22±18.92 MPa) and lowest (19.57±5.76 MPa) compressive strength were observed in MTA group after 21 days and in MTA + 2% Ze-Ag-Zn group after four days, respectively. The effect of time and 2% Ze-Ag-Zn on the compressive strength were significant (P<0.05). Mixing MTA with Ze-Ag-Zn significantly reduced and passage of time from day four to 21 significantly increased the compressive strength. Conclusions Mixing MTA with 2% Ze-Ag-Zn had an adverse effect on the compressive strength of MTA, but this combination had no cytotoxic effects. Key words:Compressive strength, Cytotoxicity, Mineral Trioxide Aggregate, Nanoparticle, Zeolite-Silver-Zinc. PMID:28298974

  7. Investigation of out of plane compressive strength of 3D printed sandwich composites

    Science.gov (United States)

    Dikshit, V.; Yap, Y. L.; Goh, G. D.; Yang, H.; Lim, J. C.; Qi, X.; Yeong, W. Y.; Wei, J.

    2016-07-01

    In this study, the 3D printing technique was utilized to manufacture the sandwich composites. Composite filament fabrication based 3D printer was used to print the face-sheet, and inkjet 3D printer was used to print the sandwich core structure. This work aims to study the compressive failure of the sandwich structure manufactured by using these two manufacturing techniques. Two different types of core structures were investigated with the same type of face-sheet configuration. The core structures were printed using photopolymer, while the face-sheet was made using nylon/glass. The out-of-plane compressive strength of the 3D printed sandwich composite structure has been examined in accordance with ASTM standards C365/C365-M and presented in this paper.

  8. Compressive Strength of Steel Frames after Welding with Micro-Jet Cooling

    Directory of Open Access Journals (Sweden)

    Hadryś D.

    2016-03-01

    Full Text Available Low carbon steel weld structures generally exhibit a very linear stress-strain relationship. In the study of strength of materials, the compressive strength is the capacity of a material or structure to withstand loads tending to reduce size of structure. It is mainly measured by plotting applied force against deformation in a testing machine. Compressive strength is a main key value for design of welded structures.The main goal of that paper was analysing of plastic properties of frame welds which were made with various parameters of micro-jet cooling. New technology of micro-jet welding could be regarded as a new way to improve plastic properties of welds. It allows to obtain welds with better mechanical properties in comparison to ordinary welding method. Furthermore it is possible to steering of weld structure and properties of the weld. There were given main information about influence of various micro-jet gases on metallographic and properties of structure steel welds.

  9. Effect Of Crumb Rubber On Compressive Strength Of Fly Ash Based Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Azmi Ahmad Azrem

    2016-01-01

    Full Text Available This study explores the effect of different percentage of crumb rubber on compressive strength of fly ash based geopolymer concrete. This research attempted to produce rubberized geopolymer concrete as an environmentally friendly, lightweight and durable product. Crumb rubber with ranged size from 73 μm to 375 μm was used in order to replace fine aggregates in geopolymer concrete. The replacements of crumb rubber were 0%, 5%, 10%, 15% and 20% in the fly ash based geopolymer concrete. The ratio of fly ash to alkaline activator was 2.5 and the ratio of Na2SiO3 to NaOH was fixed at 2.0. After the curing process, the strengths of the samples were tested on days 7 and 28. The results show that there is a reduction in all compressive strength for crumb rubber mixture, but still higher than normal rubberized concrete. Rubberized geopolymer concrete is a suitable solution in some non structural applications.

  10. Embedded NMR Sensor to Monitor Compressive Strength Development and Pore Size Distribution in Hydrating Concrete

    Directory of Open Access Journals (Sweden)

    Floriberto Díaz-Díaz

    2013-11-01

    Full Text Available In cement-based materials porosity plays an important role in determining their mechanical and transport properties. This paper describes an improved low–cost embeddable miniature NMR sensor capable of non-destructively measuring evaporable water loss and porosity refinement in low and high water-to-cement ratio cement-based materials. The sensor consists of two NdFeB magnets having their North and South poles facing each other, separated by 7 mm to allow space for a Faraday cage containing a Teflon tube and an ellipsoidal RF coil. To account for magnetic field changes due to temperature variations, and/or the presence of steel rebars, or frequency variation due to sample impedance, an external tuning circuit was employed. The sensor performance was evaluated by analyzing the transverse magnetization decay obtained with a CPMG measurement from different materials, such as a polymer phantom, fresh white and grey cement pastes with different w/c ratios and concrete with low (0.30 and high (0.6 w/c ratios. The results indicated that the sensor is capable of detecting changes in water content in fresh cement pastes and porosity refinement caused by cement hydration in hardened materials, even if they are prepared with a low w/c ratio (w/c = 0.30. The short lifetime component of the transverse relaxation rate is directly proportional to the compressive strength of concrete determined by destructive testing. The r2 (0.97 from the linear relationship observed is similar to that obtained using T2 data from a commercial Oxford Instruments 12.9 MHz spectrometer.

  11. Cadmium Alternatives for High-Strength Steel

    Science.gov (United States)

    2011-09-22

    191 19b. TELEPHONE NUMBER (include area code) 301 -342-8101 iii Table of Contents Note that original JTP section numbers are preceded by...specified. The focus of this JTP is on high-strength structural alloy steels used for various applications. Alloy AISI 4130 was used for adhesion and...NaCl) solution under constant amplitude loading to determine fatigue life using hourglass specimens prepared from high strength AISI 4340 steel. The

  12. Hydrogen degradation of high strength weldable steels

    OpenAIRE

    J. Ćwiek

    2007-01-01

    Purpose: Purpose of this paper is presentation of hydrogen degradation issue of high strength steels andespecially their welded joints. Establishing of applicable mechanisms of hydrogen-enhanced cracking was theaim of performed research.Design/methodology/approach: High strength quenched and tempered steels grade S690Q were used. Weldedjoints were prepared with typical technology used in shipyards. Susceptibility to hydrogen degradation in seawater under cathodic polarization was evaluated wi...

  13. Durability and compressive strength of blast furnace slag-based cement grout for special geotechnical applications

    Directory of Open Access Journals (Sweden)

    Ortega, J. M.

    2014-03-01

    Full Text Available Special foundations, most prominently micropiles and soil anchors, are frequently used in construction today. In Spain, the grout for these special technical applications is generally prepared with portland cement, although the codes and standards in place stipulate only the minimum compressive strength required, with no mention of cement type. Those texts also establish a range of acceptable water:cement ratios. In the present study, durability and compressive strength in cement grout prepared with blast furnace slag cement at different w/c ratios are characterised and compared to the findings for a reference portland cement grout. The results show that slag grout exhibits greater durability than the portland cement material and complies with the compressive strength requirements laid down in the respective codes.Actualmente es muy frecuente el empleo de cimentaciones especiales, entre las que destacan los micropilotes y los anclajes. En España, las lechadas de cemento para estos trabajos geotécnicos especiales se preparan habitualmente con cemento Portland, aunque las diferentes normativas al respecto no restringen el tipo de cemento a emplear, siempre que se alcance una determinada resistencia a compresión. Respecto a la dosificación de las lechadas, la normativa permite emplear diferentes relaciones agua/cemento dentro de un determinado rango. En vista de ello, en este trabajo se han caracterizado las propiedades de durabilidad y resistencia a compresión de lechadas de cemento preparadas con un cemento con escoria de alto horno y con diferentes relaciones a/c, tomando como referencia de comportamiento lechadas de cemento Portland. El uso de un cemento con escoria conlleva una mejora en la durabilidad de las lechadas, cumpliendo los requisitos de resistencia a compresión establecidos por la normativa.

  14. Comparative Evaluation of the Compressive Strength of a Direct Composite Resin and Two Laboratorial Resins

    Directory of Open Access Journals (Sweden)

    Alexandre Costa Reis BRITO

    2007-05-01

    Full Text Available Purpose: To compare the compressive strength of two commercially available laboratorial resins - Solidex® (Shofu and Cristobal® (Dentsply - to that of a direct composite resin (Concept®; Vigodent, as a control group.Method: Five specimens of each tested material were fabricated using stainless steel matrices with the following dimensions: 8 mm of internal diameter on the base, 9 mm of internal diameter on the top and 4 mm of height. The specimens were stored in distilled water for 72 hours and submitted to an axial load by the action of a 2-mm-diameter round-end tip adapted to a universal testing machine (EMIC 500. A 200 kgf load cell was used running at a crosshead speed of 0.5 mm/min. The load and the point of failure were recorded. Results: Means, in kgf, were: Concept® (Ct = 124.26; Cristobal® (C =184.63; Solidex® (S =173.58. Data (means and standard deviations were analyzed statistically by ANOVA and Tukey’s for comparisons among the groups using the SPSS software (version 10.0. Significance level was set at á=0.05 (95%. Concept® presented significantly lower (p<0.05 compressive strength than the other two materials, Cristobal® and Solidex®, which, in turn, did not differ significantly to each other.Conclusion: Cristobal® and Solidex® laboratorial resins did not show significant difference to each other and both presented compressive strength significantly higher than that of Concept® direct resin.

  15. Effect of shear strength on Hugoniot-compression curve and the equation of state of tungsten (W)

    Energy Technology Data Exchange (ETDEWEB)

    Mashimo, Tsutomu, E-mail: mashimo@gpo.kumamoto-u.ac.jp; Liu, Xun [Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555 (Japan); Kodama, Masao [Sojo University, Kumamoto 860-0082 (Japan); Zaretsky, Eugene [Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Katayama, Masahide [Itochu Techno-Solutions Corporation, Tokyo 100-6080 (Japan); Nagayama, Kunihiko [Kyushu University, Fukuoka 812-8581 (Japan)

    2016-01-21

    The Hugoniot data for highly dense polycrystalline tungsten were obtained for pressures above 200 GPa, and the equation of state (EOS) was determined taking into account shear strength effects. For this study, we have made some improvements in measurement system and analyses of the shock wave data. Symmetric-impact Hugoniot measurements were performed using the high-time resolution streak camera system equipped on a one-stage powder gun and two-stage light gas gun, where the effects of tilting and bowing of flyer plate on the Hugoniot data were carefully considered. The shock velocity–particle velocity (U{sub S}–U{sub P}) Hugoniot relation in the plastic regime was determined to be U{sub S} = 4.137 + 1.242U{sub P} km/s (U{sub P} < 2 km/s). Ultrasonic and Velocity Interferometer System for Any Reflector measurements were also performed in this study. The zero-intercept value of the U{sub S}–U{sub P} Hugoniot relation was found to be slightly larger than the ultrasonic bulk sound velocity (4.023 km/s). The hypothetical hydrostatic isothermal U{sub s}–U{sub p} Hugoniot curve, which corresponds to the hydrostatic isothermal compression curve derived from the Hugoniot data using the strength data, converged to the bulk sound velocity, clearly showing shear strength dependence in the Hugoniot data. The EOS for tungsten is derived from the hydrostatic isothermal compression curve using the strength data.

  16. Comparison of Elastic Modulus and Compressive Strength of Ariadent and Harvard Polycarboxylate Cement and Vitremer Resin Modified Glass Ionomer

    Directory of Open Access Journals (Sweden)

    Ahmadian Khoshemehr Leila

    2009-09-01

    Full Text Available Background: Luting agents are used to attach indirect restoration into or on the tooth. Poor mechanical properties of cement may be a cause of fracture of this layer and lead to caries and restoration removal. The purpose of this study was to compare the elastic modulus and compressive strength of Ariadent (A Poly and Harvard polycarboxylate (H Poly cements and Vitremer resin modified glass ionomer (RGl.Materials & Methods: In this experimental study 15 specimens were prepared form each experimental cement in Laboratory of Tehran Oil Refining Company. The cylindrical specimens were compressed in Instron machine after 24 hours. Elastic modulus and compressive strength were calculated from stress/strain curve of each specimen. One way ANOVA and Tukey tests were used for statistical analysis and P values<0.05 were considered to be statistically significant.Results: The mean elastic modulus and mean compressive strength were 2.2 GPa and 87.8MPa in H poly, 2.4 GPa and 56.5 MPa in A Poly, and 0.8GPa and 105.6 MPa in RGI, respectively. Statistical analysis showed that compressive strength and elastic modulus of both polycarboxylate cements were significantly different from hybrid ionomer (P<0.05, but the difference between elastic modulus of two types of polycarboxilate cements was not statistically significant. Compressive strength of two polycarboxilate cements were significantly different (P<0.05. Conclusion: An ideal lutting agent must have the best mechanical properties. Between the tested luttins RGl cement had the lowest elastic modulus and the highest compressive strength, but the A poly cement had the highest elastic modulus and the lowest compressive strength. Therefore none of them was the best.

  17. Steelmaking slag as aggregate for mortars: effects of particle dimension on compression strength.

    Science.gov (United States)

    Faraone, Nicola; Tonello, Gabriele; Furlani, Erika; Maschio, Stefano

    2009-11-01

    The present paper reports on the results of some experiments obtained from the production, hydration and subsequent measurement of the mechanical properties of several mortars prepared using a commercial CII/B-LL Portland cement, steelmaking slag, superplasticizer and water. Relevant parameters for the mortar preparation are the weight ratios of cement/water, the weight ratio superplasticizer/cement and between fine and granulated coarse particles. It has been demonstrated that optimisation of such parameters leads to the production of materials with mechanical properties suitable for civil engineering applications. Moreover, materials with improved compressive strength can be prepared by the use of slag containing extensive amounts of large particles.

  18. Strength and fatigue limit of fabric base composites under combined static shear and cyclic compressive stresses

    Energy Technology Data Exchange (ETDEWEB)

    Limonov, V.A.; Razin, A.F.; Mikel`sons, M.Ya. [Central Research Institute of Special Engineering, Moscow (Russian Federation)

    1992-11-01

    Under real operating conditions, assemblies and products made of composites are subjected to combined static and cyclic loads. At the planning stage, an important problem is the selection of the materials to be used and an estimate of the load-bearing capacity by complex investigation of their physicomechanical properties. In the present work, the authors studied experimentally the characteristics of strength under static uniaxial and combined loading and the effect of static shear stresses on the compressive fatigue limit of glass-fabric reinforced plastic. 7 refs., 7 figs., 2 tabs.

  19. Calcium Phosphate Bone Cements Including Sugar Surfactants: Part One—Porosity, Setting Times and Compressive Strength

    Directory of Open Access Journals (Sweden)

    Juliette Fitremann

    2010-09-01

    Full Text Available Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides, to calcium phosphate cement designed for bone reconstruction is described. Thanks to their surface activity and through their adsorption at the surface of the calcium phosphate particles, they both induced a strong increase in the porosity (quantified by Image Analysis and brought a very good workability. Other properties typically studied for these cements are reported, including setting times, compressive strength, cohesion in water, and effect of sterilization on these properties. The whole study brought good insight in the interest of adding these mild surfactants to improve several properties of the calcium phosphate cement, without impairing their function.

  20. Average density and porosity of high-strength lightweight concrete

    Directory of Open Access Journals (Sweden)

    A.S. Inozemtcev

    2014-11-01

    Full Text Available The analysis results of high-strength lightweight concrete (HSLWC structure are presented in this paper. The X-ray tomography, optical microscopy and other methods are used for researching of average density and porosity. It has been revealed that mixtures of HSLWC with density 1300…1500 kg/m3 have a homogeneous structure. The developed concrete has a uniform distribution of the hollow filler and a uniform layer of cement-mineral matrix. The highly saturated gas phase which is divided by denser large particles of quartz sand and products of cement hydration in the contact area allow forming a composite material with low average density, big porosity (up to 40% and high strength (compressive strength is more than 40 MPa. Special modifiers increase adhesion, compacts structure in the contact area, decrease water absorption of high-strength lightweight concrete (up to 1 % and ensure its high water resistance (water resistance coefficient is more than 0.95.

  1. High toughness-high strength iron alloy

    Science.gov (United States)

    Stephens, J. R.; Witzke, W. R. (Inventor)

    1980-01-01

    An iron alloy is provided which exhibits strength and toughness characteristics at cryogenic temperatures. The alloy consists essentially of about 10 to 16 percent by weight nickel, about 0.1 to 1.0 percent by weight aluminum, and 0 to about 3 percent by weight copper, with the balance being essentially iron. The iron alloy is produced by a process which includes cold rolling at room temperature and subsequent heat treatment.

  2. Performances of the High Strength Low Heat Pump Concrete (HLPC)

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The effects of mineral admixtures on fluidity,mechanical and hydrational exothermic behavior were studied.The results show that,double-adding ways,i e,fly ash and slag were added at the same time,not only improves the fluidity of fresh concrete with low W/B and compensates the lower early compressive strength of harden concrete caused by high adding amount of fly ash, but also greatly reduces the highest temperature rise, exothermic rate and total heat liberation of 3 day of binder pastes in HLPC, and postponed the arrival time of the highest temperature rise. HLPC was prepared and applied to project practice successfully.

  3. High-Strength, Superelastic Compounds

    Science.gov (United States)

    Stanford, Malcolm; Noebe, Ronald; Dellacorte, Christopher; Bigelow, Glen; Thomas, Fransua

    2013-01-01

    can be used in the heat treatment process, less energy will be consumed, and there will be less dimensional distortion and quench cracking. This results in fewer scrap parts, less material waste from large amounts of material removal, and fewer machining steps to rework parts that are out of specification. This material has a combination of properties that have been previously unobtainable. The material has a Young s modulus of approximately 95 GPa (about half that of conventional steels), moderate density (10 to 15% lower than conventional steels), excellent corrosion resistance, and high hardness (58 to 62 HRC). These properties make this material uniquely suited for advanced bearings.

  4. Study on the strength of frozen clay at high confining pressure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An extensive test program was conducted on East China deep clay to investigate mechanical behavior in the process of axial compression and triaxial compression.In addition,the effect of negative temperature and confining pressure on the strength of frozen clay was analyzed.It is concluded that the stress-strain curves at high confining pressure belong to the strain hardening type and its strength almost corresponds to confining pressure in the range of tested confined stress.With respect to temperature,the strength increases when the temperature decreases.

  5. Ultimate uniaxial compressive strength of stiffened panel with opening under lateral pressure

    Directory of Open Access Journals (Sweden)

    Yu Chang-Li

    2015-06-01

    Full Text Available This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.

  6. Ultimate uniaxial compressive strength of stiffened panel with opening under lateral pressure

    Directory of Open Access Journals (Sweden)

    Chang-Li Yu

    2015-03-01

    Full Text Available This paper concentrated on the ultimate uniaxial compressive strength of stiffened panel with opening under lateral load and also studied the design-oriented formulae. For this purpose, three series of well executed experiments on longitudinal stiffened panel with rectangular opening subjected to the combined load have been selected as test models. The finite element analysis package, ABAQUS, is used for simulation with considering the large elasticplastic deflection behavior of stiffened panels. The feasibility of the numerical procedure is verified by a good agreement of experimental results and numerical results. More cases studies are executed employing nonlinear finite element method to analyze the influence of design variables on the ultimate strength of stiffened panel with opening under combined pressure. Based on data, two design formulae corresponding to different opening types are fitted, and accuracy of them is illustrated to demonstrate that they could be applied to basic design of practical engineering structure.

  7. Development of High Specific Strength Envelope Materials

    Science.gov (United States)

    Komatsu, Keiji; Sano, Masa-Aki; Kakuta, Yoshiaki

    Progress in materials technology has produced a much more durable synthetic fabric envelope for the non-rigid airship. Flexible materials are required to form airship envelopes, ballonets, load curtains, gas bags and covering rigid structures. Polybenzoxazole fiber (Zylon) and polyalirate fiber (Vectran) show high specific tensile strength, so that we developed membrane using these high specific tensile strength fibers as a load carrier. The main material developed is a Zylon or Vectran load carrier sealed internally with a polyurethane bonded inner gas retention film (EVOH). The external surface provides weather protecting with, for instance, a titanium oxide integrated polyurethane or Tedlar film. The mechanical test results show that tensile strength 1,000 N/cm is attained with weight less than 230g/m2. In addition to the mechanical properties, temperature dependence of the joint strength and solar absorptivity and emissivity of the surface are measured. 

  8. Long-Term Isothermal Aging Effects on Carbon Fabric-Reinforced PMR-15 Composites: Compression Strength

    Science.gov (United States)

    Bowles, Kenneth J.; Roberts, Gary D.; Kamvouris, John E.

    1996-01-01

    A study was conducted to determine the effects of long-term isothermal thermo-oxidative aging on the compressive properties of T-650-35 fabric reinforced PMR-15 composites. The temperatures that were studied were 204, 260, 288, 316, and 343 C. Specimens of different geometries were evaluated. Cut edge-to-surface ratios of 0.03 to 0.89 were fabricated and aged. Aging times extended to a period in excess of 15,000 hours for the lower temperature runs. The unaged and aged specimens were tested in compression in accordance with ASTM D-695. Both thin and thick (plasma) specimens were tested. Three specimens were tested at each time/temperature/geometry condition. The failure modes appeared to be initiated by fiber kinking with longitudinal, interlaminar splitting. In general, it appears that the thermo-oxidative degradation of the compression strength of the composite material may occur by both thermal (time-dependent) and oxidative (weight-loss) mechanisms. Both mechanisms appear to be specimen-thickness dependent.

  9. Influence of Curing Age and Mix Composition on Compressive Strength of Volcanic Ash Blended Cement Laterized Concrete

    Directory of Open Access Journals (Sweden)

    Babafemi A.J.

    2012-01-01

    Full Text Available This study investigates the influence of curing age and mix proportions on the compressive strength of volcanic ash (VA blended cement laterized concrete. A total of 288 cubes of 100mm dimensions were cast and cured in water for 3, 7, 28, 56, 90 and 120 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively while a control mix of 28-day target strength of 25N/mm2 (using British Method was adopted. The results show that the compressive strength of the VA-blended cement laterized concrete increased with the increase in curing age but decreased as the VA and laterite (LAT contents increased. The optimum replacement level was 20%LAT/20%VA. At this level the compressive strength increased with curing age at a decreasing rate beyond 28 days. The target compressive strength of 25N/mm2 was achieved for this mixture at 90 days of curing. VA content and curing age was noted to have significant effect (α ≤ 0.5 on the compressive strength of the VA-blended cement laterized concrete.

  10. Quasi-Static and High Strain Rate Compressive Response of Injection-Molded Cenosphere/HDPE Syntactic Foam

    Science.gov (United States)

    Bharath Kumar, B. R.; Singh, Ashish Kumar; Doddamani, Mrityunjay; Luong, Dung D.; Gupta, Nikhil

    2016-07-01

    High strain rate compressive properties of high-density polyethylene (HDPE) matrix syntactic foams containing cenosphere filler are investigated. Thermoplastic matrix syntactic foams have not been studied extensively for high strain rate deformation response despite interest in them for lightweight underwater vehicle structures and consumer products. Quasi-static compression tests are conducted at 10-4 s-1, 10-3 s-1 and 10-2 s-1 strain rates. Further, a split-Hopkinson pressure bar is utilized for characterizing syntactic foams for high strain rate compression. The compressive strength of syntactic foams is higher than that of HDPE resin at the same strain rate. Yield strength shows an increasing trend with strain rate. The average yield strength values at high strain rates are almost twice the values obtained at 10-4 s-1 for HDPE resin and syntactic foams. Theoretical models are used to estimate the effectiveness of cenospheres in reinforcing syntactic foams.

  11. Application of alkaliphilic biofilm-forming bacteria to improve compressive strength of cement-sand mortar.

    Science.gov (United States)

    Park, Sung-Jin; Chun, Woo-Young; Kim, Wha-Jung; Ghim, Sa-Youl

    2012-03-01

    The application of microorganisms in the field of construction material is rapidly increasing worldwide; however, almost all studies that were investigated were bacterial sources with mineral-producing activity and not with organic substances. The difference in the efficiency of using bacteria as an organic agent is that it could improve the durability of cement material. This study aimed to assess the use of biofilm-forming microorganisms as binding agents to increase the compressive strength of cement-sand material. We isolated 13 alkaliphilic biofilmforming bacteria (ABB) from a cement tetrapod block in the West Sea, Korea. Using 16S RNA sequence analysis, the ABB were partially identified as Bacillus algicola KNUC501 and Exiguobacterium marinum KNUC513. KNUC513 was selected for further study following analysis of pH and biofilm formation. Cement-sand mortar cubes containing KNUC513 exhibited greater compressive strength than mineral-forming bacteria (Sporosarcina pasteurii and Arthrobacter crystallopoietes KNUC403). To determine the biofilm effect, Dnase I was used to suppress the biofilm formation of KNUC513. Field emission scanning electron microscopy image revealed the direct involvement of organic-inorganic substance in cement-sand mortar.

  12. Hierarchical Order of Influence of Mix Variables Affecting Compressive Strength of Sustainable Concrete Containing Fly Ash, Copper Slag, Silica Fume, and Fibres

    Directory of Open Access Journals (Sweden)

    Sakthieswaran Natarajan

    2014-01-01

    Full Text Available Experiments have been conducted to study the effect of addition of fly ash, copper slag, and steel and polypropylene fibres on compressive strength of concrete and to determine the hierarchical order of influence of the mix variables in affecting the strength using cluster analysis experimentally. While fly ash and copper slag are used for partial replacement of cement and fine aggregate, respectively, defined quantities of steel and polypropylene fibres were added to the mixes. It is found from the experimental study that, in general, irrespective of the presence or absence of fibres, (i for a given copper slag-fine aggregate ratio, increase in fly ash-cement ratio the concrete strength decreases and with the increase in copper slag-sand ratio also the rate of strength decrease and (ii for a given fly ash-cement ratio, increase in copper slag-fine aggregate ratio increases the strength of the concrete. From the cluster analysis, it is found that the quantities of coarse and fine aggregate present have high influence in affecting the strength. It is also observed that the quantities of fly ash and copper slag used as substitutes have equal “influence” in affecting the strength. Marginal effect of addition of fibres in the compression strength of concrete is also revealed by the cluster analysis.

  13. Development of high strength high toughness third generation advanced high strength steels

    Science.gov (United States)

    Martis, Codrick John

    Third generation advanced high strength steels (AHSS's) are emerging as very important engineering materials for structural applications. These steels have high specific strength and thus will contribute significantly to weight reduction in automotive and other structural component. In this investigation two such low carbon low alloy steels (LCLA) with high silicon content (1.6-2wt %) has been developed. These two steel alloys were subjected to single step and two step austempering in the temperature range of 260-399°C to obtain desired microstructures and mechanical properties. Austempering heat treatment was carried out for 2 hours in a molten salt bath. The microstructures were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and optical metallography. Quantitative analysis was carried out by image analysis technique. The effect of austempering temperature on the mechanical properties of these two alloys was examined. The influence of microstructures on the mechanical properties of alloys was also studied. Austempering heat treatment resulted in fine carbide free bainitic ferrite and high carbon austenite microstructure in the samples austempered above Ms temperature, whereas tempered martensite and austenite microstructure was obtained in samples austempered below Ms temperature. Yield strength, tensile strength and fracture toughness were found to increase as the austempering temperature decreases, whereas ductility increases as the austempering temperature increases. Tensile strength in the range of 1276MPa -1658 MPa and the fracture toughness in the range of 80-141MPa√m were obtained in these two steels. Volume fractions of different phases present and their lath sizes are related to the mechanical properties. Austempered samples consisting of mixed microstructure of bainitic ferrite and tempered martensite phases resulted in the exceptional combination of strength and toughness.

  14. High rate fabrication of compression molded components

    Energy Technology Data Exchange (ETDEWEB)

    Matsen, Marc R.; Negley, Mark A.; Dykstra, William C.; Smith, Glen L.; Miller, Robert J.

    2016-04-19

    A method for fabricating a thermoplastic composite component comprises inductively heating a thermoplastic pre-form with a first induction coil by inducing current to flow in susceptor wires disposed throughout the pre-form, inductively heating smart susceptors in a molding tool to a leveling temperature with a second induction coil by applying a high-strength magnetic field having a magnetic flux that passes through surfaces of the smart susceptors, shaping the magnetic flux that passes through surfaces of the smart susceptors to flow substantially parallel to a molding surface of the smart susceptors, placing the heated pre-form between the heated smart susceptors; and applying molding pressure to the pre-form to form the composite component.

  15. Experimental investigation and empirical modelling of FDM process for compressive strength improvement

    Directory of Open Access Journals (Sweden)

    Anoop K. Sood

    2012-01-01

    Full Text Available Fused deposition modelling (FDM is gaining distinct advantage in manufacturing industries because of its ability to manufacture parts with complex shapes without any tooling requirement and human interface. The properties of FDM built parts exhibit high dependence on process parameters and can be improved by setting parameters at suitable levels. Anisotropic and brittle nature of build part makes it important to study the effect of process parameters to the resistance to compressive loading for enhancing service life of functional parts. Hence, the present work focuses on extensive study to understand the effect of five important parameters such as layer thickness, part build orientation, raster angle, raster width and air gap on the compressive stress of test specimen. The study not only provides insight into complex dependency of compressive stress on process parameters but also develops a statistically validated predictive equation. The equation is used to find optimal parameter setting through quantum-behaved particle swarm optimization (QPSO. As FDM process is a highly complex one and process parameters influence the responses in a non linear manner, compressive stress is predicted using artificial neural network (ANN and is compared with predictive equation.

  16. Chloride-Ion Penetrability and Mechanical Analysis of High Strength Concrete with Copper Slag

    Directory of Open Access Journals (Sweden)

    Savaş Erdem

    2014-05-01

    Full Text Available The use of waste materials and industrial by-products in high-strength concrete could increase the sustainability of the construction industry. In this study, the potential of using copper slag as coarse aggregate in high-strength concrete was experimentally investigated. The effects of replacing gravel coarse aggregate by copper slag particles on the compressive strength, chloride ion- migration, water permeability and impact resistance of high-strength concretes were evaluated. Incorporating copper slag coarse particles resulted in a compressive strength increase of about 14 % on average partly due to the low Ca/Si ratio through the interface area of this concrete (more homogenous internal structure as confirmed by the energy dispersive X-ray micro chemical analysis. It was also found that the copper slag high-strength concrete provided better ductility and had much greater load carrying capacity compared to gravel high-strength concrete under dynamic conditions. Finally, it was observed that in comparison to the high strength concrete with slag, the chloride migration coefficient from non-steady state migration was approximately 30 % greater in the gravel high-strength concrete.

  17. The strength of ruby from X-ray diffraction under non-hydrostatic compression to 68 GPa

    Science.gov (United States)

    Dong, Haini; Dorfman, Susannah M.; Wang, Jianghua; He, Duanwei; Duffy, Thomas S.

    2014-07-01

    Polycrystalline ruby (α-Al2O3:Cr3+), a widely used pressure calibrant in high-pressure experiments, was compressed to 68.1 GPa at room temperature under non-hydrostatic conditions in a diamond anvil cell. Angle-dispersive X-ray diffraction experiments in a radial geometry were conducted at beamline X17C of the National Synchrotron Light Source. The stress state of ruby at high pressure and room temperature was analyzed based on the measured lattice strain. The differential stress of ruby increases with pressure from ~3.4 % of the shear modulus at 18.5 GPa to ~6.5 % at 68.1 GPa. The polycrystalline ruby sample can support a maximum differential stress of ~16 GPa at 68.1 GPa under non-hydrostatic compression. The results of this study provide a better understanding of the mechanical properties of this important material for high-pressure science. From a synthesis of existing data for strong ceramic materials, we find that the high-pressure yield strength correlates well with the ambient pressure Vickers hardness.

  18. Modeling and Optimization of Compressive Strength of Hollow Sandcrete Block with Rice Husk Ash Admixture

    Directory of Open Access Journals (Sweden)

    2016-11-01

    Full Text Available The paper presents the report of an investigation into the model development and optimization of the compressive strength of 55/45 to 70/30 cement/Rice Husk Ash (RHA in hollow sandcrete block. The low cost and local availability potential of RHA, a pozzolanic material gasps for exploitation. The study applies the Scheffe\\'s optimization approach to obtain a mathematical model of the form f(xi1 ,xi2 ,xi3 xi4 , where x are proportions of the concrete components, viz: cement, RHA, sand and water. Scheffe\\'s i experimental design techniques are followed to mould various hollow block samples measuring 450mm x 225mm x 150mm and tested for 28 days strength. The task involved experimentation and design, applying the second order polynomial characterization process of the simplex lattice method. The model adequacy is checked using the control factors. Finally, a software is prepared to handle the design computation process to take the desired property of the mix, and generate the optimal mix ratios. Reversibly, any mix ratios can be desired and the attainable strength obtained.

  19. Repeatability and Reproducibility of Compression Strength Measurements Conducted According to ASTM E9

    Science.gov (United States)

    Luecke, William E.; Ma, Li; Graham, Stephen M.; Adler, Matthew A.

    2010-01-01

    Ten commercial laboratories participated in an interlaboratory study to establish the repeatability and reproducibility of compression strength tests conducted according to ASTM International Standard Test Method E9. The test employed a cylindrical aluminum AA2024-T351 test specimen. Participants measured elastic modulus and 0.2 % offset yield strength, YS(0.2 % offset), using an extensometer attached to the specimen. The repeatability and reproducibility of the yield strength measurement, expressed as coefficient of variations were cv(sub r)= 0.011 and cv(sub R)= 0.020 The reproducibility of the test across the laboratories was among the best that has been reported for uniaxial tests. The reported data indicated that using diametrically opposed extensometers, instead of a single extensometer doubled the precision of the test method. Laboratories that did not lubricate the ends of the specimen measured yield stresses and elastic moduli that were smaller than those measured in laboratories that lubricated the specimen ends. A finite element analysis of the test specimen deformation for frictionless and perfect friction could not explain the discrepancy, however. The modulus measured from stress-strain data were reanalyzed using a technique that finds the optimal fit range, and applies several quality checks to the data. The error in modulus measurements from stress-strain curves generally increased as the fit range decreased to less than 40 % of the stress range.

  20. Optimization of compressive strength in admixture-reinforced cement-based grouts

    Directory of Open Access Journals (Sweden)

    Sahin Zaimoglu, A.

    2007-12-01

    Full Text Available The Taguchi method was used in this study to optimize the unconfined (7-, 14- and 28-day compressive strength of cement-based grouts with bentonite, fly ash and silica fume admixtures. The experiments were designed using an L16 orthogonal array in which the three factors considered were bentonite (0%, 0.5%, 1.0% and 3%, fly ash (10%, 20%, 30% and 40% and silica fume (0%, 5%, 10% and 20% content. The experimental results, which were analyzed by ANOVA and the Taguchi method, showed that fly ash and silica fume content play a significant role in unconfined compressive strength. The optimum conditions were found to be: 0% bentonite, 10% fly ash, 20% silica fume and 28 days of curing time. The maximum unconfined compressive strength reached under the above optimum conditions was 17.1 MPa.En el presente trabajo se ha intentado optimizar, mediante el método de Taguchi, las resistencias a compresión (a las edades de 7, 14 y 28 días de lechadas de cemento reforzadas con bentonita, cenizas volantes y humo de sílice. Se diseñaron los experimentos de acuerdo con un arreglo ortogonal tipo L16 en el que se contemplaban tres factores: la bentonita (0, 0,5, 1 y 3%, las cenizas volantes (10, 20, 30 y 40% y el humo de sílice (0, 5, 10 y 20% (porcentajes en peso del sólido. Los datos obtenidos se analizaron con mediante ANOVA y el método de Taguchi. De acuerdo con los resultados experimentales, el contenido tanto de cenizas volantes como de humo de sílice desempeña un papel significativo en la resistencia a compresión. Por otra parte, las condiciones óptimas que se han identificado son: 0% bentonita, 10% cenizas volantes, 20% humo de sílice y 28 días de tiempo de curado. La resistencia a compresión máxima conseguida en las anteriores condiciones era de 17,1 MPa.

  1. Poly(acrylamide-MWNTs hybrid hydrogel with extremely high mechanical strength

    Directory of Open Access Journals (Sweden)

    Feng Huanhuan

    2016-01-01

    Full Text Available Poly(acrylamide-multiwalled carbon nanotubes (PAAm-MWNTs hybrid hydrogels were prepared through the radiation-induced polymerization and crosslinking of the aqueous solution of acrylamide and well-dispersed MWNTs for the first time. The PAAm gels obtained by the radiation-induced polymerization and cosslinking showed very high mechanical strengths, and the PAAm-MWNTs hybrid hydrogels had improved mechanical properties compared with the PAAm gels, and hence the PAAm-MWNTs hybrid hydrogels showed extremely high compressive and tensile strengths. The hybrid hydrogels with water contents more than 80 wt.% usually did not fracture even at compressive strengths close to or even more than 60 MPa and strains more than 97%. And the hybrid hydrogels had very high elongations (more than 2000% in some cases, especially when the water content was high. The tensile strengths were in sub-MPa. The hybrid PAAm-MWNTs hydrogel is one of the strongest hydrogel even made.

  2. Springback analysis of ultra high strength steel

    Science.gov (United States)

    Tenma, Kenji; Kina, Futoshi; Suzuki, Wataru

    2013-12-01

    It is an inevitable trend in the automotive industry to apply more and more high strength steels and even ultra-high strength steels. Even though these materials are more difficult to process the development time of forming tools must be reduced. In order to keep the development time under control, simulation tools are used to verify the forming process in advance. At Aoi Machine Industry a project has been executed to accurately simulate springback of ultra-high strength steels in order to reduce the tool tryout time. In the first phase of the project the simulation settings were optimized based on B-Pillar model A made of Dual Phase 980. In the second phase, it was verified with B-Pillar model B whether these simulation settings were usable as general setting. Results showed that with the right settings it is very well possible to accurately simulate springback of ultra-high strength steels. In the third phase the project the stamping of a B-Pillar of Dual Phase 1180 was studied.

  3. The Effect of Variation of Molarity of Alkali Activator and Fine Aggregate Content on the Compressive Strength of the Fly Ash: Palm Oil Fuel Ash Based Geopolymer Mortar

    Directory of Open Access Journals (Sweden)

    Iftekhair Ibnul Bashar

    2014-01-01

    Full Text Available The effect of molarity of alkali activator, manufactured sand (M-sand, and quarry dust (QD on the compressive strength of palm oil fuel ash (POFA and fly ash (FA based geopolymer mortar was investigated and reported. The variable investigated includes the quantities of replacement levels of M-sand, QD, and conventional mining sand (N-sand in two concentrated alkaline solutions; the contents of alkaline solution, water, POFA/FA ratio, and curing condition remained constant. The results show that an average of 76% of the 28-day compressive strength was found at the age of 3 days. The rate of strength development from 3 to 7 days was found between 12 and 16% and it was found much less beyond this period. The addition of 100% M-sand and QD shows insignificant strength reduction compared to mixtures with 100% N-sand. The particle angularity and texture of fine aggregates played a significant role in the strength development due to the filling and packing ability. The rough texture and surface of QD enables stronger bond between the paste and the fine aggregate. The concentration of alkaline solution increased the reaction rate and thus enhanced the development of early age strength. The use of M-sand and QD in the development of geopolymer concrete is recommended as the strength variation between these waste materials and conventional sand is not high.

  4. High-strength bioresorbable Fe-Ag nanocomposite scaffolds: Processing and properties

    Science.gov (United States)

    Sharipova, Aliya; Psakhie, Sergey G.; Swain, Sanjaya K.; Gutmanas, Elazar Y.; Gotman, Irena

    2015-10-01

    High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na2SO4 and K2CO3 salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy's law. Scaffolds with 50% and 55% porosity exhibited high compressive strength (18-22 MPa), compressive strength of 8-12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6-6 cm2) is close to the range of trabecular bone.

  5. High-strength bioresorbable Fe–Ag nanocomposite scaffolds: Processing and properties

    Energy Technology Data Exchange (ETDEWEB)

    Sharipova, Aliya [Department of Materials Science and Technology, Techion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); Skolkovo Institute of Science and Technology, Skolkovo, 143025 (Russian Federation); Psakhie, Sergey G. [Skolkovo Institute of Science and Technology, Skolkovo, 143025 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Swain, Sanjaya K. [Department of Materials Science and Technology, Techion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il; Gotman, Irena [Department of Materials Science and Technology, Techion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    High strength ductile iron-silver nanocomposite scaffolds were fabricated employing high energy attrition milling of micron-submicron powders, followed by cold sintering/high pressure consolidation. Particulate leaching method with soluble Na{sub 2}SO{sub 4} and K{sub 2}CO{sub 3} salts as porogens was used to create scaffolds with 50, 55, 60 and 73% volume fraction of pores. Part of specimens was annealed at 600, 800 and 900°C. Specimens were characterized employing X-ray diffraction, scanning electron microscopy (SEM) with electron probe microanalysis (EDS) and high resolution SEM. Mechanical properties were measured in compression and permeability was measured in permeameter based on Darcy’s law. Scaffolds with 50% and 55% porosity exhibited high compressive strength (18–22 MPa), compressive strength of 8–12 MPa was observed for scaffolds with 73% porosity. Treatments at 800 and 900°C result in increase of strength and ductility with some coarsening of microstructure. Best combination of compressive strength (15 MPa) and permeability (0.6{sup −6} cm{sup 2}) is close to the range of trabecular bone.

  6. Degradation of permeability resistance of high strength concrete after combustion

    Institute of Scientific and Technical Information of China (English)

    Min LI; Hongtao KAO; Chunxiang QIAN

    2008-01-01

    To evaluate the remaining durability of con-crete materials after combustion, the permeability of high strength concrete (HSC) after combustion was studied. The transport behavior of chloride ion, water and air in concrete after combustion and the effect of temperature, strength grade, and aggregation on the permeability of HSC after combustion are investigated by chloride ion permeability coefficient (Dc), water permeability coef-ficient (Dw) and air permeability coefficient (Da). The experiment results show that all three permeability coeffi-cients commendably reflect changes of permeability. The permeability coefficient increases with the evaluation tem-perature. After the same temperature, the permeability coefficient of HSC is lower than that of normal strength concrete (NSC). However, the degree of degradation of permeability coefficient of HSC is greater than that of NSC. The permeability resistance of HSC containing limestone is better than that of HSC containing basalt. Combining changes of compressive strength and per-meability, the remaining durability of concrete materials after combustion is appropriately evaluated.

  7. Compressive Strength Properties of Natural Gas Hydrate Pellet by Continuous Extrusion from a Twin-Roll System

    Directory of Open Access Journals (Sweden)

    Yun-Hoo Lee

    2013-01-01

    Full Text Available This study investigates the compressive strength of natural gas hydrate (NGH pellet strip extruded from die holes of a twin-roll press for continuous pelletizing (TPCP. The lab-scale TPCP was newly developed, where NGH powder was continuously fed and extruded into strip-type pellet between twin rolls. The system was specifically designed for future expansion towards mass production of solid form NGH. It is shown that the compressive strength of NGH pellet strip heavily depends on parameters in the extrusion process, such as feeding pressure, pressure ratio, and rotational speed. The mechanism of TPCP, along with the compressive strength and density of pellets, is discussed in terms of its feasibility for producing NGH pellets in the future.

  8. Comparison of the compressive strength of impregnated and nonimpregnated eucalyptus subjected to two different pressures and impregnation times

    Directory of Open Access Journals (Sweden)

    Waldemir Rodrigues

    2004-06-01

    Full Text Available The durability of wood is affected by several factors. For this reason, much research has been done on a variety of chemical compounds for impregnating wood, aimed at preserving it while simultaneously improving its properties. Recent studies of the properties of impregnated wood have demonstrated the possibility of substantially improving its mechanical characteristics. Thus, the purpose of this work was to compare the strength to parallel compression of wooden fibers (Eucalyptus grandis, both nonimpregnated and impregnated with a monocomponent resin, from the standpoint of pressure and impregnation time, aiming at its structural utilization. The results demonstrate that the compressive strength of impregnated test specimens is greater than that of nonimpregnated ones, indicating that monocomponent polyurethane resin can be considered suitable for impregnating wood, since it increases the compressive strength of eucalyptus.

  9. Electrical impedance spectroscopy measurements to estimate the uniaxial compressive strength of a fault breccia

    Indian Academy of Sciences (India)

    Sair Kahraman; Michael Alber

    2014-10-01

    Fault breccias are usually not suitable for preparing smooth specimens or else the preparation of such specimens is tedious, time consuming and expensive. To develop a predictive model for the uniaxial compressive strength (UCS) of a fault breccia from electrical resistivity values obtained from the electrical impedance spectroscopy measurements, twenty-four samples of a fault breccia were tested in the laboratory. The UCS values were correlated with corresponding resistivity values and a strong correlation between them could not be found. However, a strong correlation was found for the samples having volumetric block proportion (VBP) of 25–75%. In addition, it was seen that VBP strongly correlated with resistivity. It was concluded that the UCS of the tested breccia can be estimated from resistivity for the samples having VBP of 25–75%.

  10. Inlfuence of Specimen Size on Compression Behavior of Cement Paste and Mortar under High Strain Rates

    Institute of Scientific and Technical Information of China (English)

    CHEN Xudong; CHEN Chen; QIAN Pingping; XU Lingyu

    2016-01-01

    Static and dynamic compression tests were carried out on mortar and paste specimens of three sizes (f68 mm×32 mm,f59 mm×29.5 mm andf32 mm×16 mm) to study the inlfuence of specimen size on the compression behavior of cement-based materials under high strain rates. The static tests were applied using a universal servo-hydraulic system, and the dynamic tests were applied by a spilt Hopkinson pressure bar (SHPB) system. The experimental results show that for mortar and paste specimens, the dynamic compressive strength is greater than the quasi-static one, and the dynamic compressive strength for specimens of large size is lower than those of small size. However, the dynamic increase factors (DIF) has an opposite trend. Obviously, both strain rate and size effect exist in mortar and paste. The test results were then analyzed using Weibull, Carpinteri and Bažant’s size effect laws. A good agreement between these three laws and the test results was reached on the compressive strength. However, for the experimental results of paste and cement mortar, the size effect is not evident for the peak strain and elastic modulus of paste and cement mortar.

  11. Prediction of zeolite-cement-sand unconfined compressive strength using polynomial neural network

    Science.gov (United States)

    MolaAbasi, H.; Shooshpasha, I.

    2016-04-01

    The improvement of local soils with cement and zeolite can provide great benefits, including strengthening slopes in slope stability problems, stabilizing problematic soils and preventing soil liquefaction. Recently, dosage methodologies are being developed for improved soils based on a rational criterion as it exists in concrete technology. There are numerous earlier studies showing the possibility of relating Unconfined Compressive Strength (UCS) and Cemented sand (CS) parameters (voids/cement ratio) as a power function fits. Taking into account the fact that the existing equations are incapable of estimating UCS for zeolite cemented sand mixture (ZCS) well, artificial intelligence methods are used for forecasting them. Polynomial-type neural network is applied to estimate the UCS from more simply determined index properties such as zeolite and cement content, porosity as well as curing time. In order to assess the merits of the proposed approach, a total number of 216 unconfined compressive tests have been done. A comparison is carried out between the experimentally measured UCS with the predictions in order to evaluate the performance of the current method. The results demonstrate that generalized polynomial-type neural network has a great ability for prediction of the UCS. At the end sensitivity analysis of the polynomial model is applied to study the influence of input parameters on model output. The sensitivity analysis reveals that cement and zeolite content have significant influence on predicting UCS.

  12. Characterization of compression strength of granite-epoxy composites using design of experiments

    Directory of Open Access Journals (Sweden)

    Antonio Piratelli-Filho

    2008-12-01

    Full Text Available This paper presents a processing study of the polymer matrix composite (PMC developed with an epoxy polymeric matrix reinforced with particulate ceramic granite. This PMC composite has been reported to be used as structural parts of machine tools and Coordinate Measuring Machines due to its superior vibration damping characteristics and reduced processing cycle over cast iron. The investigated processing variables were epoxy content and particle size and the mechanical characterization was carried out by compressive tests. Rejects of granite with particle size smaller than 500 µm were prepared by crushing, milling and classification operations. The powder was mixed with different compositions of epoxy resin, between 15 and 20% in weight. An experiment was planned and executed according to the Factorial design technique using two variables at two levels. The obtained cylindrical samples were submitted to compressive strength tests and the results showed a maximum resistance of 114.23 MPa at 20 wt. (% epoxy, value close to that of the literature.

  13. Enhanced densification, strength and molecular mechanisms in shock compressed porous silicon

    Science.gov (United States)

    Lane, J. Matthew D.; Vogler, Tracy J.

    2015-06-01

    In most porous materials, void collapse during shock compression couples mechanical energy to thermal energy. Increased temperature drives up pressures and lowers densities in the final Hugoniot states as compared to full-density samples. Some materials, however, exhibit an anomalous enhanced densification in their Hugoniot states when porosity is introduced. We have recently shown that silicon is such a material, and demonstrated a molecular mechanism for the effect using molecular simulation. We will review results from large-scale non-equilibrium molecular dynamics (NEMD) and Hugoniotstat simulations of shock compressed porous silicon, highlighting the mechanism by which porosity produces local shear which nucleate partial phase transition and localized melting at shock pressures below typical thresholds in these materials. Further, we will characterize the stress states and strength of the material as a function of porosity from 5 to 50 percent and with various porosity microstructures. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. A Numerical Study on the Edgewise Compression Strength of Sandwich Structures with Facesheet-Core Disbonds

    Science.gov (United States)

    Bergan, Andrew C.

    2017-01-01

    Damage tolerant design approaches require determination of critical damage modes and flaw sizes in order to establish nondestructive evaluation detection requirements. A finite element model is developed to assess the effect of circular facesheet-core disbonds on the strength of sandwich specimens subjected to edgewise compressive loads for the purpose of predicting the critical flaw size for a variety of design parameters. Postbuckling analyses are conducted in which an initial imperfection is seeded using results from a linear buckling analysis. Both the virtual crack closure technique (VCCT) and cohesive elements are considered for modeling disbond growth. Predictions from analyses using the VCCT and analyses using cohesive elements are in good correlation. A series of parametric analyses are conducted to investigate the effect of core thickness and material, facesheet layup, facesheet-core interface properties, and curvature on the criticality of facesheet-core disbonds of various sizes. The results from these analyses provide a basis for determining the critical flaw size for facesheet-core disbonds subjected to edgewise compression loads and, therefore, nondestructive evaluation flaw detection requirements for this configuration.

  15. The effect of different parameters on the development of compressive strength of oil palm shell geopolymer concrete.

    Science.gov (United States)

    Kupaei, Ramin Hosseini; Alengaram, U Johnson; Jumaat, Mohd Zamin

    2014-01-01

    This paper presents the experimental results of an on-going research project on geopolymer lightweight concrete using two locally available waste materials--low calcium fly ash (FA) and oil palm shell (OPS)--as the binder and lightweight coarse aggregate, respectively. OPS was pretreated with three different alkaline solutions of sodium hydroxide (NaOH), potassium hydroxide, and sodium silicate as well as polyvinyl alcohol (PVA) for 30 days; afterwards, oil palm shell geopolymer lightweight concrete (OPSGPC) was cast by using both pretreated and untreated OPSs. The effect of these solutions on the water absorption of OPS, and the development of compressive strength in different curing conditions of OPSGPC produced by pretreated OPS were investigated; subsequently the influence of NaOH concentration, alkaline solution to FA ratio (A/FA), and different curing regimes on the compressive strength and density of OPSGPC produced by untreated OPS was inspected. The 24-hour water absorption value for OPS pretreated with 20% and 50% PVA solution was about 4% compared to 23% for untreated OPS. OPSGPC produced from OPS treated with 50% PVA solution produced the highest compressive strength of about 30 MPa in ambient cured condition. The pretreatment with alkaline solution did not have a significant positive effect on the water absorption of OPS aggregate and the compressive strength of OPSGPC. The result revealed that a maximum compressive strength of 32 MPa could be obtained at a temperature of 65°C and curing period of 4 days. This investigation also found that an A/FA ratio of 0.45 has the optimum amount of alkaline liquid and it resulted in the highest level of compressive strength.

  16. The Effect of Different Parameters on the Development of Compressive Strength of Oil Palm Shell Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Ramin Hosseini Kupaei

    2014-01-01

    Full Text Available This paper presents the experimental results of an on-going research project on geopolymer lightweight concrete using two locally available waste materials—low calcium fly ash (FA and oil palm shell (OPS—as the binder and lightweight coarse aggregate, respectively. OPS was pretreated with three different alkaline solutions of sodium hydroxide (NaOH, potassium hydroxide, and sodium silicate as well as polyvinyl alcohol (PVA for 30 days; afterwards, oil palm shell geopolymer lightweight concrete (OPSGPC was cast by using both pretreated and untreated OPSs. The effect of these solutions on the water absorption of OPS, and the development of compressive strength in different curing conditions of OPSGPC produced by pretreated OPS were investigated; subsequently the influence of NaOH concentration, alkaline solution to FA ratio (A/FA, and different curing regimes on the compressive strength and density of OPSGPC produced by untreated OPS was inspected. The 24-hour water absorption value for OPS pretreated with 20% and 50% PVA solution was about 4% compared to 23% for untreated OPS. OPSGPC produced from OPS treated with 50% PVA solution produced the highest compressive strength of about 30 MPa in ambient cured condition. The pretreatment with alkaline solution did not have a significant positive effect on the water absorption of OPS aggregate and the compressive strength of OPSGPC. The result revealed that a maximum compressive strength of 32 MPa could be obtained at a temperature of 65°C and curing period of 4 days. This investigation also found that an A/FA ratio of 0.45 has the optimum amount of alkaline liquid and it resulted in the highest level of compressive strength.

  17. Compressive strength and frost heave resistance of different types of semi-rigid base materials after freeze-thaw cycles

    Institute of Scientific and Technical Information of China (English)

    ZhenYa Liu; JingYu Liu; QingZhi Wang; JianKun Liu

    2015-01-01

    Freeze-thaw damage is the most common disease of semi-rigid bases in cold regions, which may greatly affect the dura-bility of roadways. In this study, the compressive strength and frost resistance of four different types of semi-rigid bases (lime-fly ash-stabilized sand, cement-stabilized sand, lime-fly ash-stabilized gravel, and cement-stabilized gravel) are assessed by varying the materials content. Based on freeze-thaw and compressive strength tests, this paper presents the performance of the different materials, each having different physical properties, and the optimal amounts of materials contents are proposed.

  18. Compressive Strength Prediction of Square Concrete Columns Retrofitted with External Steel Collars

    Directory of Open Access Journals (Sweden)

    Pudjisuryadi, P.

    2013-01-01

    Full Text Available Transverse confining stress in concrete members, commonly provided by transverse reinforcement, has been recognized to enhance strength and ductility. Nowadays, the confining method has been further developed to external confinement approach. This type of confinement can be used for retrofitting existing concrete columns. Many external confining techniques have been proven to be successful in retrofitting circular columns. However, for square or rectangular columns, providing effective confining stress by external retrofitting method is not a simple task due to high stress concentration at column’s corners. This paper proposes an analytical model to predict the peak strength of square concrete columns confined by external steel collars. Comparison with the experimental results showed that the model can predict the peak strength reasonably well. However, it should be noted that relatively larger amount of steel is needed to achieve comparable column strength enhancement when it is compared with those of conve tional internally-confined columns.

  19. Compressive and diametral tensile strength of glass ionomer cements Resistência à compressão e à tração diametral de cimentos de ionômero de vidro

    OpenAIRE

    Eduardo Bresciani; Terezinha de Jesus Esteves Barata; Ticiane Cestari Fagundes; Akimi Adachi; Marina Martins Terrin; Maria Fidela de Lima Navarro

    2004-01-01

    The aim of this study was to compare, in different periods of time, the compressive and diametral tensile strength of a traditional high viscous glass ionomer cement: Fuji IX (GC Corporation), with two new Brazilian GIC's: Vitro-Molar (DFL) and Bioglass R (Biodinamica), all indicated for the Atraumatic Restorative Treatment (ART) technique. Fifteen disk specimens (6.0mm diameter x 3.0mm height) for the diametral tensile strength (DTS) test and fifteen cylindrical specimens (6.0mm diameter x 1...

  20. The relationship between unconfined compressive strength and leachate concentration of stabilised contaminated sediment

    Science.gov (United States)

    Kabir Aliyu, Mohammed; Tarmizi Abd Karim, Ahmad; -Ming Chan, Chee

    2016-11-01

    Solidification/Stabilization (S/S) treatment was used in this study to immobilise copper (Cu) in contaminated river sediment. The sediment was artificially contaminated by spiking the solution of Copper sulphate (CuSO4.5H2O) to so as to get an average of 1000 ppm target concentration. Portland composite cement and Rice husk ash (RHA) were used as S/S agents. The amount of cement added to the mixture was l0% and while rice husk ash at the rate of 5%, l0%, 15% and 20% to the total dry weight of the mixture and then was cured for 7, 14 and 28 days. The unconfined compressive strength test (UCS) and toxicity characteristic leaching procedure (TCLP) were used to evaluate the effectiveness of the S/S treatments. From the results obtained it indicates that the partial replacement of cement with RHA in the binder system has increased the strength and the leachate concentration of copper was less in the treated sediment samples if compared with the untreated ones.

  1. Formulation of Reduction Rate for Ultimate Compressive Strength of Stiffened Panel Induced by Opening

    Institute of Scientific and Technical Information of China (English)

    于昌利; LEE Joo-sung

    2014-01-01

    The-main-objective-of-this-study-is-to-numerically-investigate-the-characteristics-of-ultimate-compressive-strength-of-stiffened-panels-with-opening-and-also-to-fit-the-design-oriented-formulae.-For-this-purpose,-three-series-of-well-executed-experimental-data-on-longitudinally-stiffened-steel-plates-with-and-without-opening-subjected-to-the-uniform-axial-in-pane-load-which-is-carried-out-to-study-the-buckling-and-post-buckling-up-to-the-final-failure-are-chosen.-Also,-a-nonlinear-finite-element-method-capable-of-efficiently-analyzing-the-large-elasto-plastic-deflection-behavior-of-stiffened-panels-is-developed-and-used-for-simulation.-The-feasibility-of-the-present-simulation-process-is-confirmed-by-a-good-agreement-with-the-experimental-results.-More-case-studies-are-developed-employing-the-simulation-process-to-analyze-the-influence-of-various-design-variables-on-the-reduction-rate-of-ultimate-strength-of-stiffened-panel-induced-by-opening.-Based-on-the-computed-results,-two-design-formulae-are-fitted-and-the-accuracy-of-design-formulae-is-studied.-Furthermore,-the-viability-of-the-design-formulae-for-practical-engineering-is-proved.

  2. Compressive Strength and Water Permeability Performance of Micronised Biomass Silica Concrete

    Directory of Open Access Journals (Sweden)

    S.H. Adnan

    2009-12-01

    Full Text Available Concrete is a common material that is widely used in construction industry. Cement is the main material component for producing concrete but its production has lead into CO2 emission. This work presents a study on Micronised Biomass Silica (MBS that can be used as pozzolan material which can enhance the quality of concrete. The material can be produced from a by-product of biomass agricultural waste but for this study rice husk has been used. From the chemical analysis, MBS has a chemical composition that is fulfill the standard requirement for becoming pozzolan material. The result of MBS concrete shows that the MBS material can enhance the performance of concrete by increasing the compressive strength development and reducing the water permeability. The drawback of MBS is the workability of fresh concrete but can be rectify by using superplasticizer. By replacing up to 12% of cement, MBS material gives the highest performance in term of strength and permeability of the concrete.

  3. Effect of Industrial By-Products on Unconfined Compressive Strength of Solidified Organic Marine Clayey Soils

    Directory of Open Access Journals (Sweden)

    Chan-Gi Park

    2015-08-01

    Full Text Available The use of industrial by-products as admixture to ASTM Type I cement (ordinary Portland cement (OPC was investigated with the objective of improving the solidification of organic marine clayey soils. The industrial by-products considered in this paper were oyster-shell powder (OSP, steelmaking slag dust (SMS and fuel-gas-desulfurized (FGD gypsum. The industrial by-products were added to OPC at a ratio of 5% based on dry weight to produce a mixture used to solidify organic marine clayey soils. The dosage ratios of mixtures to organic marine clayey soils were 5, 10 and 15% on a dry weight basis. Unconfined compressive strength (UCS test after 28 days revealed that the highest strength was obtained with the OPC + SMS 15% mixing ratio. The UCS of specimens treated with this mixture was >500 kPa, compared with 300 kPa for specimens treated with a 15% OPC + OSP mixture and 200 kPa when 15% of OPC was used alone. These results were attributed to the more active hydration and pozzolanic reaction of the OPC + SMS mixture. This hypothesis was verified through X-ray diffraction (XRD and scanning electron microscopy (SEM analyses, and was confirmed by variations in the calcium carbonate (CaCO3 content of the materials during curing.

  4. Study on compressive strength of self compacting mortar cubes under normal & electric oven curing methods

    Science.gov (United States)

    Prasanna Venkatesh, G. J.; Vivek, S. S.; Dhinakaran, G.

    2017-07-01

    In the majority of civil engineering applications, the basic building blocks were the masonry units. Those masonry units were developed as a monolithic structure by plastering process with the help of binding agents namely mud, lime, cement and their combinations. In recent advancements, the mortar study plays an important role in crack repairs, structural rehabilitation, retrofitting, pointing and plastering operations. The rheology of mortar includes flowable, passing and filling properties which were analogous with the behaviour of self compacting concrete. In self compacting (SC) mortar cubes, the cement was replaced by mineral admixtures namely silica fume (SF) from 5% to 20% (with an increment of 5%), metakaolin (MK) from 10% to 30% (with an increment of 10%) and ground granulated blast furnace slag (GGBS) from 25% to 75% (with an increment of 25%). The ratio between cement and fine aggregate was kept constant as 1: 2 for all normal and self compacting mortar mixes. The accelerated curing namely electric oven curing with the differential temperature of 128°C for the period of 4 hours was adopted. It was found that the compressive strength obtained from the normal and electric oven method of curing was higher for self compacting mortar cubes than normal mortar cube. The cement replacement by 15% SF, 20% MK and 25%GGBS obtained higher strength under both curing conditions.

  5. The Bendability of Ultra High strength Steels

    Science.gov (United States)

    Hazra, S. K.; Efthymiadis, P.; Alamoudi, A.; Kumar, R. L. V.; Shollock, B.; Dashwood, R.

    2016-08-01

    Automotive manufacturers have been reducing the weight of their vehicles to meet increasingly stringent environmental legislation that reflects public demand. A strategy is to use higher strength materials for parts with reduced cross-sections. However, such materials are less formable than traditional grades. The frequent result is increased processing and piece costs. 3D roll forming is a novel and flexible process: it is estimated that a quarter of the structure of a vehicle can be made with a single set of tooling. Unlike stamping, this process requires material with low work hardening rates. In this paper, we present results of ultra high strength steels that have low elongation in a tension but display high formability in bending through the suppression of the necking response.

  6. CWICOM: A Highly Integrated & Innovative CCSDS Image Compression ASIC

    Science.gov (United States)

    Poupat, Jean-Luc; Vitulli, Raffaele

    2013-08-01

    The space market is more and more demanding in terms of on image compression performances. The earth observation satellites instrument resolution, the agility and the swath are continuously increasing. It multiplies by 10 the volume of picture acquired on one orbit. In parallel, the satellites size and mass are decreasing, requiring innovative electronic technologies reducing size, mass and power consumption. Astrium, leader on the market of the combined solutions for compression and memory for space application, has developed a new image compression ASIC which is presented in this paper. CWICOM is a high performance and innovative image compression ASIC developed by Astrium in the frame of the ESA contract n°22011/08/NLL/LvH. The objective of this ESA contract is to develop a radiation hardened ASIC that implements the CCSDS 122.0-B-1 Standard for Image Data Compression, that has a SpaceWire interface for configuring and controlling the device, and that is compatible with Sentinel-2 interface and with similar Earth Observation missions. CWICOM stands for CCSDS Wavelet Image COMpression ASIC. It is a large dynamic, large image and very high speed image compression ASIC potentially relevant for compression of any 2D image with bi-dimensional data correlation such as Earth observation, scientific data compression… The paper presents some of the main aspects of the CWICOM development, such as the algorithm and specification, the innovative memory organization, the validation approach and the status of the project.

  7. Experimental investigation of bond strength under high loading rates

    Science.gov (United States)

    Michal, Mathias; Keuser, Manfred; Solomos, George; Peroni, Marco; Larcher, Martin; Esteban, Beatriz

    2015-09-01

    The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw) and the Joint Research Centre (JRC) in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

  8. Experimental investigation of bond strength under high loading rates

    Directory of Open Access Journals (Sweden)

    Michal Mathias

    2015-01-01

    Full Text Available The structural behaviour of reinforced concrete is governed significantly by the transmission of forces between steel and concrete. The bond is of special importance for the overlapping joint and anchoring of the reinforcement, where rigid bond is required. It also plays an important role in the rotational capacity of plastic hinges, where a ductile bond behaviour is preferable. Similar to the mechanical properties of concrete and steel also the characteristics of their interaction changes with the velocity of the applied loading. For smooth steel bars with its main bond mechanisms of adhesion and friction, nearly no influence of loading rate is reported in literature. In contrast, a high rate dependence can be found for the nowadays mainly used deformed bars. For mechanical interlock, where ribs of the reinforcing steel are bracing concrete material surrounding the bar, one reason can be assumed to be in direct connection with the increase of concrete compressive strength. For splitting failure of bond, characterized by the concrete tensile strength, an even higher dynamic increase is observed. For the design of Structures exposed to blast or impact loading the knowledge of a rate dependent bond stress-slip relationship is required to consider safety and economical aspects at the same time. The bond behaviour of reinforced concrete has been investigated with different experimental methods at the University of the Bundeswehr Munich (UniBw and the Joint Research Centre (JRC in Ispra. Both static and dynamic tests have been carried out, where innovative experimental apparatuses have been used. The bond stress-slip relationship and maximum pull-out-forces for varying diameter of the bar, concrete compressive strength and loading rates have been obtained. It is expected that these experimental results will contribute to a better understanding of the rate dependent bond behaviour and will serve for calibration of numerical models.

  9. Structural strength of cancellous specimens from bovine femur under cyclic compression

    Directory of Open Access Journals (Sweden)

    Kaori Endo

    2016-01-01

    Full Text Available The incidence of osteoporotic fractures was estimated as nine million worldwide in 2000, with particular occurrence at the proximity of joints rich in cancellous bone. Although most of these fractures spontaneously heal, some fractures progressively collapse during the early post-fracture period. Prediction of bone fragility during progressive collapse following initial fracture is clinically important. However, the mechanism of collapse, especially the gradual loss of the height in the cancellous bone region, is not clearly proved. The strength of cancellous bone after yield stress is difficult to predict since structural and mechanical strength cannot be determined a priori. The purpose of this study was to identify whether the baseline structure and volume of cancellous bone contributed to the change in cancellous bone strength under cyclic loading. A total of fifteen cubic cancellous bone specimens were obtained from two 2-year-old bovines and divided into three groups by collection regions: femoral head, neck, and proximal metaphysis. Structural indices of each 5-mm cubic specimen were determined using micro-computed tomography. Specimens were then subjected to five cycles of uniaxial compressive loading at 0.05 mm/min with initial 20 N loading, 0.3 mm displacement, and then unloading to 0.2 mm with 0.1 mm displacement for five successive cycles. Elastic modulus and yield stress of cancellous bone decreased exponentially during five loading cycles. The decrease ratio of yield stress from baseline to fifth cycle was strongly correlated with bone volume fraction (BV/TV, r = 0.96, p < 0.01 and structural model index (SMI, r = − 0.81, p < 0.01. The decrease ratio of elastic modulus from baseline to fifth cycle was also correlated with BV/TV (r = 0.80, p < 0.01 and SMI (r = − 0.78, p < 0.01. These data indicate that structural deterioration of cancellous bone is associated with bone strength after yield stress. This study suggests that

  10. Uniaxial Compressive Strength and Fracture Mode of Lake Ice at Moderate Strain Rates Based on a Digital Speckle Correlation Method for Deformation Measurement

    Directory of Open Access Journals (Sweden)

    Jijian Lian

    2017-05-01

    Full Text Available Better understanding of the complex mechanical properties of ice is the foundation to predict the ice fail process and avoid potential ice threats. In the present study, uniaxial compressive strength and fracture mode of natural lake ice are investigated over moderate strain-rate range of 0.4–10 s−1 at −5 °C and −10 °C. The digital speckle correlation method (DSCM is used for deformation measurement through constructing artificial speckle on ice sample surface in advance, and two dynamic load cells are employed to measure the dynamic load for monitoring the equilibrium of two ends’ forces under high-speed loading. The relationships between uniaxial compressive strength and strain-rate, temperature, loading direction, and air porosity are investigated, and the fracture mode of ice at moderate rates is also discussed. The experimental results show that there exists a significant difference between true strain-rate and nominal strain-rate derived from actuator displacement under dynamic loading conditions. Over the employed strain-rate range, the dynamic uniaxial compressive strength of lake ice shows positive strain-rate sensitivity and decreases with increasing temperature. Ice obtains greater strength values when it is with lower air porosity and loaded vertically. The fracture mode of ice seems to be a combination of splitting failure and crushing failure.

  11. A comparative study for the concrete compressive strength estimation using neural network and neuro-fuzzy modelling approaches

    Science.gov (United States)

    Bilgehan, Mahmut

    2011-03-01

    In this paper, adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) model have been successfully used for the evaluation of relationships between concrete compressive strength and ultrasonic pulse velocity (UPV) values using the experimental data obtained from many cores taken from different reinforced concrete structures having different ages and unknown ratios of concrete mixtures. A comparative study is made using the neural nets and neuro-fuzzy (NF) techniques. Statistic measures were used to evaluate the performance of the models. Comparing of the results, it is found that the proposed ANFIS architecture with Gaussian membership function is found to perform better than the multilayer feed-forward ANN learning by backpropagation algorithm. The final results show that especially the ANFIS modelling may constitute an efficient tool for prediction of the concrete compressive strength. Architectures of the ANFIS and neural network established in the current study perform sufficiently in the estimation of concrete compressive strength, and particularly ANFIS model estimates closely follow the desired values. Both ANFIS and ANN techniques can be used in conditions where too many structures are to be examined in a restricted time. The presented approaches enable to practically find concrete strengths in the existing reinforced concrete structures, whose records of concrete mixture ratios are not available or present. Thus, researchers can easily evaluate the compressive strength of concrete specimens using UPV and density values. These methods also contribute to a remarkable reduction in the computational time without any significant loss of accuracy. A comparison of the results clearly shows that particularly the NF approach can be used effectively to predict the compressive strength of concrete using UPV and density values. In addition, these model architectures can be used as a nondestructive procedure for health monitoring of

  12. Effects of coating thickness and interfacial roughness on cracking and delamination strength of WC-Co coating measured by ring compression test

    Science.gov (United States)

    Kato, Masahiko; Nazul, Mahmoud; Itti, Takeshi; Akebono, Hiroyuki; Sugeta, Atsushi; Mitani, Eiji

    2014-08-01

    The effects of coating thickness and interfacial roughness on the interfacial fracture toughness of tungsten carbide-cobalt (WC-Co) coatings were evaluated using a ring compression test. WC-Co powder was sprayed on steel (JIS:SS400) rings by a high-velocity air- fuel method in coatings with various thicknesses and values of interfacial roughness. The ring compression test was carried out, and the cracking and delamination behavior of the coatings was observed using charge-coupled-device cameras. The results showed that cracking perpendicular to the loading direction occurred in the coatings during the ring compression test, and the cracking strength obtained from the ring compression test decreased slightly with increasing coating thickness, but was independent of the interfacial roughness. Upon further increase of the compression load, the coatings delaminated from the substrate. The interfacial fracture toughness calculated from the delamination of the coatings during the ring compression test decreased with increasing coating thickness and increased with increasing interfacial roughness.

  13. Hydrogen trapping in high-strength steels

    Energy Technology Data Exchange (ETDEWEB)

    Pound, B.G. [SRI International, Menlo Park, CA (United States). Materials Research Center

    1998-10-09

    Hydrogen trapping in three high-strength steels -- AerMet 100 and AISI 4340 and H11 -- was studied using a potentiostatic pulse technique. Irreversible trapping constants (k) and hydrogen entry fluxes were determined for these alloys in 1 mol/1 acetic acid/1 mol/1 sodium acetate. The order of the k values for the three steels and two 18Ni maraging steels previously studies inversely parallels their threshold stress intensities for stress corrosion cracking (K{sub 1SCC}). Irreversible trapping in AerMet 100 varies with aging temperature and appears to depend on the type of carbide (Fe{sub 3}C or M{sub 2}C) present. For 4340 steel, k can be correlated with K{sub 1SCC} over a range of yield strengths. The change in k is consistent with a change in the principal type of irreversible trap from matrix boundaries to incoherent Fe{sub 3}C. The principal irreversible traps in H11 at high yield strengths are thought to be similar to those in 4340 steel.

  14. Improving the standard of the standard for glass ionomers: an alternative to the compressive fracture strength test for consideration?

    LENUS (Irish Health Repository)

    Dowling, Adam H

    2012-03-01

    Three strength tests (compressive, three point flexure and biaxial) were performed on three glass ionomer (GI) restoratives to assess the most appropriate methodology in terms of validity and reliability. The influence of mixing induced variability on the data sets generated were eliminated by using encapsulated GIs.

  15. EFFECT OF SODIUM HYDROXIDE CONCENTRATION ON FRESH PROPERTIES AND COMPRESSIVE STRENGTH OF SELF-COMPACTING GEOPOLYMER CONCRETE

    Directory of Open Access Journals (Sweden)

    FAREED AHMED MEMON

    2013-02-01

    Full Text Available This paper reports the results of the laboratory tests conducted to investigate the effect of sodium hydroxide concentration on the fresh properties and compressive strength of self-compacting geopolymer concrete (SCGC. The experiments were conducted by varying the concentration of sodium hydroxide from 8 M to 14 M. Test methods such as Slump flow, V-Funnel, L-box and J-Ring were used to assess the workability characteristics of SCGC. The test specimens were cured at 70°C for a period of 48 hours and then kept in room temperature until the day of testing. Compressive strength test was carried out at the ages of 1, 3, 7 and 28 days. Test results indicate that concentration variation of sodium hydroxide had least effect on the fresh properties of SCGC. With the increase in sodium hydroxide concentration, the workability of fresh concrete was slightly reduced; however, the corresponding compressive strength was increased. Concrete samples with sodium hydroxide concentration of 12 M produced maximum compressive strength.

  16. THE EFFECT OF VOLUME VARIATION OF SILVER NANOPARTICLE SOLUTION TOWARDS THE POROSITY AND COMPRESSIVE STRENGTH OF MORTAR

    Directory of Open Access Journals (Sweden)

    W.S.B. Dwandaru

    2016-10-01

    Full Text Available As the world is growing rapidly, people need better building materials such as mortar. The aim of this research is to determine the effect of adding silver nanoparticle solution towards the porosity and compressive strength of mortar. This research was started by making silver nanoparticle solution from nitrate silver (AgNO3. The solution is then characterized using Uv-Vis spectrophotometer. 5 mM silver nanoparticle is added in the process of mortar production with volume variation of the silver nanoparticle solution. The porosity, compressive strength, and the content of mortar were determined by digital scale, universal testing machine, and X-ray diffraction, respectively. For silver nanoparticle solution volumes of (in mL 0, 5, 10, 15, 20, and 25 the porosity obtained are (in % 20.38, 19.48, 19.42, 18.9, 17.8, and 17.5, respectively. The best increase in compressive strength is obtained for (in MPa 29,068, 29,308, and 31,385, with nanoparticle solution volumes of (in mL 5, 10, and 15   Keywords: mortar, silver nanoparticle, compressive strength

  17. Microstructure, characterizations, functionality and compressive strength of cement-based materials using zinc oxide nanoparticles as an additive

    Energy Technology Data Exchange (ETDEWEB)

    Nochaiya, Thanongsak [Department of Physics, Faculty of Science, Naresuan University, Phitsanulok 65000 (Thailand); Sekine, Yoshika [Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka, Kanagawa 259-1292 (Japan); Choopun, Supab [Applied Physics Research Laboratory, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Chaipanich, Arnon, E-mail: arnon.chaipanich@cmu.ac.th [Advanced Cement-Based Materials Research Unit, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-05-05

    Highlights: • Nano zinc oxide was used as an additive material. • Microstructure and phase characterization of pastes were characterized using SEM and XRD. • TGA and FTIR were also used to determine the hydration reaction. • Compressive strength of ZnO mixes was found to increase at 28 days. - Abstract: Zinc oxide nanoparticles as a nanophotocatalyst has great potential for self-cleaning applications in concrete structures, its effects on the cement hydration, setting time and compressive strength are also important when using it in practice. This paper reports the effects of zinc oxide nanoparticles, as an additive material, on properties of cement-based materials. Setting time, compressive strength and porosity of mortars were investigated. Microstructure and morphology of pastes were characterized using scanning electron microscope and X-ray diffraction (XRD), respectively. Moreover, thermal gravimetric analysis (TGA) and Fourier-transform infrared spectrometer (FTIR) were also used to determine the hydration reaction. The results show that Portland cement paste with additional ZnO was found to slightly increase the water requirement while the setting time presented prolongation period than the control mix. However, compressive strength of ZnO mixes was found to be higher than that of PC mix up to 15% (at 28 days) via filler effect. Microstructure, XRD and TGA results of ZnO pastes show less hydration products before 28 days but similar at 28 days. In addition, FTIR results confirmed the retardation when ZnO was partially added in Portland cement pastes.

  18. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Maziasz, P.J.

    1996-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile ductility due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications despite their excellent corrosion properties. With regard to the ductility problem, alloy development efforts have produced significant improvements, with ductilities of 10-20% and tensile yield strengths as high as 500 MPa being reported. Likewise, initial improvements in creep resistance have been realized through small additions of Mo, Nb, and Zr.

  19. Comparative evaluation of compressive strength and flexural strength of conventional core materials with nanohybrid composite resin core material an in vitro study.

    Science.gov (United States)

    Jayanthi, Narasimha; Vinod, V

    2013-09-01

    Several dental materials have been used for core build-up procedures. Most of these materials were not specifically developed for this purpose, but as a consequence of their properties, have found application in core build-up procedures. Improvements in composites and the development of nanocomposites have led to their use as a core build up material due to their superior mechanical properties, optical properties and ease of handling. However it is not clear if they have better mechanical properties than the conventional core build up materials like amalgam, GIC and dual cure composite core build up material. The strength of the core material is very important and this study was undertaken to compare the mechanical properties of materials used for direct core foundations. The differences between the compressive strength and flexural strength of Filtek Z350 nanocomposite with conventional core build up materials like Amalgam, Vitremer GIC and Fluorocore were tested. Cylindrical plexi glass split molds of dimension 6 ± 1 mm [height] x4 ± 1 mm [diameter] were used to fabricate 15 samples of each core material for testing the compressive strength and rectangular plexi glass split molds of dimension 25 ± 1 mm [length] x 2 ± 1 mm[height] x2 ± 1 mm [width] used for fabricating samples for flexural strength. The samples were stored a water bath at 250 °C for 24 h before testing. The samples were tested using a Universal Instron testing machine. The results of the study showed that Fluorocore had the highest compressive strength and flexural strength followed by Filtek Z350 [nanocomposite] Amalgam had the least flexural strength and Vitremer GIC had the least compressive strength. Thus flurocore and nanocomposite are stronger than other core build up materials and hence should be preferred over other conventional core build up materials in extensively damaged teeth.

  20. Flexural Strength Evaluation of Reinforced Concrete Members with Ultra High Performance Concrete

    Directory of Open Access Journals (Sweden)

    Baek-Il Bae

    2016-01-01

    Full Text Available Flexural strength evaluation models for steel fiber reinforced ultra high strength concrete were suggested and evaluated with test results. Suggested flexural strength models were composed of compression stress blocks and tension stress blocks. Rectangular stress block, triangular stress block, and real distribution shape of stress were used on compression side. Under tension, rectangular stress block distributed to whole area of tension side and partial area of tension side was used. The last model for tension side is realistic stress distribution. All these models were verified with test result which was carried out in this study. Test was conducted by four-point loading with 2,000 kN actuator for slender beam specimen. Additional verifications were carried out with previous researches on flexural strength of steel fiber reinforced concrete or ultra high strength concrete. Total of 21 test specimens were evaluated. As a result of comparison for flexural strength of section, neutral axis depth at ultimate state, models with triangular compression stress block, and strain-softening type tension stress block can be used as exact solution for ultra high performance concrete. For the conservative and convenient design of section, modified rectangular stress block model can be used with strain softening type tension stress block.

  1. Irreversible volume expansion of a TATB-based composite and compressive strength

    Science.gov (United States)

    Thompson, Darla Graff; Schwarz, Ricardo B.; DeLuca, Racci

    2017-01-01

    It has long been known that compacted composites containing TATB (triaminotrinitrobenzene) crystals undergo "ratchet growth," an irreversible volume expansion upon thermal cycling. A clear mechanism has not been established for this phenomenon, but is believed to arise from the highly-anisotropic CTE of TATB crystals and interactions caused by compaction. Explosive performance depends fundamentally on bulk density, so the effect may be important. PBX 9502 is a plastic bonded explosive containing 95 wt% TATB crystals. We have monitored uniaxial length changes of PBX 9502 specimens for various thermal cycles providing mechanistic insight. Post-cycled specimens were compression tested to determine if mechanical properties correlated with the detailed thermal history.

  2. Compression testing spherical particles for strength: Theory of the meridian crack test and implementation for microscopic fused quartz

    Science.gov (United States)

    Pejchal, Václav; Žagar, Goran; Charvet, Raphaël; Dénéréaz, Cyril; Mortensen, Andreas

    2017-02-01

    We show that uniaxial compression testing of spherical particles can give unambiguous access to their tensile strength as governed by surface flaws if one uses pairs of elasto-plastic platens, tailoring their hardness in order to control the relative area of particle-to-platen contact during the test. This eliminates the development of contact microcracks that are typically found to govern particle fracture when hard platens are used. We show that, if the platen materials are well chosen, one can probe a range of stress states for which it is known that particle failure was initiated along the surface, under elevated hoop stress within a region situated remote from the points of load application. Specifically, platens must be chosen such that particles tend to fracture when the ratio of projected contact area radius to particle radius exceeds a specific value that depends on the Poisson ratio of the particles. With fused quartz of Poisson ratio 0.17, this specific ratio value equals 0.65. We demonstrate the approach using microscopic fused quartz spheres 40±20 μm in diameter as a testbench material; with those particles hardened steel serves as an appropriate platen material. Their strength values are statistically distributed; this is addressed using several platen materials. The resulting bank of data is interpreted using established survival-analysis methods, namely the non-parametric product-limit estimator. We also give a maximum likelihood estimation of the particle strength Weibull distribution parameters derived from the ensemble of data after left-truncation and/or right-censoring of data points situated inside of the range of unambiguous surface fracture strength measurement for each platen material. This gives a Weibull modulus of 6.3 and characteristic strength of 890 MPa for the fused quartz particles. These values are significantly lower than what is produced in high-strength fused quartz fibers of comparable diameter; the difference is most likely

  3. Freezing and Thawing Durability of Very High Strength Concrete

    Directory of Open Access Journals (Sweden)

    Sameer Hamoush

    2011-01-01

    Full Text Available Problem statement: The newly developed Very High Strength Concrete (VHSC, having compressive strengths of 29 ksi and flexural strengths of 6 ksi, represents a breakthrough in concrete technology. Study to further enhance the properties of this new concrete is continuing. Approach: The objective of this study is to investigate the effect of exposing Very High Strength Concrete (VHSC specimens to rapid freeze/thaw cycles. Twenty one specimens were tested according to the Standards of the American Society for Testing and Materials ASTM C215, ASTM C666 and ASTM C78. Results: One hundred freeze/thaw cycles were performed on the VHSC specimens. Change in specimen’s dimensions and material’s properties were recorded at zero, forty, seventy and one hundred cycles. Dimensions and properties considered were: dimension of cross section, length, weight, Dynamic Moduli, Poisson’s Ratio, durability factor and Modulus of Rupture. Conclusion/Recommendations: The test results indicated that VHSC is good freeze-thaw resistance (durability factor > 85% and can avoid freeze/thaw damage. Freeze- thaw cycling did not significantly affect VHSC specimens’ cross sectional dimensions, length, or Poisson’s Ratio. However, there was a decrease in the specimens’ weight with the increase in number of freeze/thaw cycles, but the decrease was very slim indicating little or no deterioration has occur. Moreover, the fine voids exist in VHSC greatly lower the freezing point of any trapped water, making the material less susceptible to Freeze- Thaw damage.

  4. High-strength iron aluminide alloys

    Energy Technology Data Exchange (ETDEWEB)

    McKamey, C.G.; Marrero-Santos, Y.; Maziasz, P.J.

    1995-06-01

    Past studies have shown that binary Fe{sub 3}Al possesses low creep-rupture strength compared to many other alloys, with creep-rupture lives of less than 5 h being reported for tests conducted at 593{degrees}C and 207 MPa. The combination of poor creep resistance and low room-temperature tensile density due to a susceptibility to environmentally-induced dynamic hydrogen embrittlement has limited use of these alloys for structural applications, despite their excellent corrosion properties. Improvements in room temperature tensile ductility have been realized mainly through alloying effects, changes in thermomechanical processing to control microstructure, and by control of the specimen`s surface condition. Ductilities of 10-20% and tensile yield strengths as high as 500 MPa have been reported. In terms of creep-rupture strength, small additions of Mo, Nb, and Zr have produced significant improvements, but at the expense of weldability and room-temperature tensile ductility. Recently an alloy containing these additions, designated FA-180, was shown to exhibit a creep-rupture life of over 2000 h after a heat treatment of 1 h at 1150{degrees}C. This study presents the results of creep-rupture tests at various test temperatures and stresses and discusses the results as part of our effort to understand the strengthening mechanisms involved with heat treatment at 1150{degrees}C.

  5. Age- and sex-related regional compressive strength characteristics of human lumbar vertebrae in osteoporosis

    Directory of Open Access Journals (Sweden)

    Márta Kurutz

    2008-12-01

    Full Text Available Márta Kurutz1, Judit Donáth3, Miklós Gálos2, Péter Varga1, Béla Fornet41Department of Structural Mechanics; 2Department of Construction Materials, Budapest University of Technology and Economics, Budapest, Hungary; 3Department of Reumatology, National Institute for Reumatology, Budapest, Hungary; 4Department of Radiology, County Hospital András Jósa, Nyiregyháza, HungaryObjective: To obtain the compressive load bearing and energy absorption capacity of lumbar vertebrae of osteoporotic elderly for the everyday medical praxis in terms of the simple diagnostic data, like computed tomography (CT, densitometry, age, and sex.Methods: Compressive test of 54 osteoporotic cadaver vertebrae L1 and L2, 16 males and 38 females (age range 43–93, mean age 71.6 ± 13.3 years, mean bone mineral density (BMD 0.377 ± 0.089 g/cm2, mean T-score −5.57 ± 0.79, Z-score −4.05 ± 0.77 was investigated. Based on the load-displacement diagrams and the measured geometrical parameters of vertebral bodies, proportional, ultimate and yield stresses and strains, Young’s modulus, ductility and energy absorption capacity were determined. Three vertebral regions were distinguished: superior, central and inferior regions, but certain parameters were calculated for the upper/lower intermediate layers, as well. Cross-sectional areas, and certain bone tissue parameters were determined by image analysis of CT pictures of vertebrae. Sex- and age-related decline functions and trends of strength characteristics were determined.Results: Size-corrected failure load was 15%–25% smaller in women, proportional and ultimate stresses were about 30%–35% smaller for women in any region, and 20%–25% higher in central regions for both sexes. Young’s moduli were about 30% smaller in women in any region, and 20%–25% smaller in the central region for both sexes. Small strains were higher in males, large strains were higher in females, namely, proportional strains were

  6. Comparative experimental study of dynamic compressive strength of mortar with glass and basalt fibres

    Directory of Open Access Journals (Sweden)

    Kruszka Leopold

    2015-01-01

    Full Text Available Specimen reinforced with glass and basalt fibers were prepared using Standard Portland cement (CEM I, 52.5 R as prescribed by EN 197-1 and standard sand, in accordance with EN 196-1. From this cementitious mixture, a reference cement mortar without fibers was first prepared. Compressive strength, modulus of elasticity, and mod of fracture were determined for all specimens. Static and dynamic properties were investigated using Instron testing machine and split Hopkinson pressure bar, respectively. Content of the glass fibers in the mortar does not influence the fracture stress at static loading conditions in a clearly observed way. Moreover at dynamic range 5% content of the fiber results in a significant drop of fracture stress. Analysis of the basalt fibers influence on the fracture stress shows that optimal content of this reinforcement is equal to 3% for both static and dynamic loading conditions. Further increase of the fiber share gives the opposite effect, i.e. drop of the fracture stress.

  7. Compressive strength of concrete by partial replacement of cement with metakaolin

    Science.gov (United States)

    Ganesh, Y. S. V.; Durgaiyya, P.; Shivanarayana, Ch.; Prasad, D. S. V.

    2017-07-01

    Metakaolin or calcined kaolin, other type of pozzolan, produced by calcination has the capability to replace silica fume as an alternative material. Supplementary cementitious materials have been widely used all over the world in concrete due to their economic and environmental benefits; hence, they have drawn much attention in recent years. Mineral admixtures such as fly ash, rice husk ash, silica fume etc. are more commonly used SCMs. They help in obtaining both higher performance and economy. Metakaolin is also one of such non - conventional material, which can be utilized beneficially in the construction industry. This paper presents the results of an experimental investigations carried out to find the suitability of metakaolin in production of concrete. In the present work, the results of a study carried out to investigate the effects of Metakaolin on compressive strength of concrete are presented. The referral concrete M30 was made using 43 grade OPC and the other mixes were prepared by replacing part of OPC with Metakaolin. The replacement levels were 5%, 10%, 15% and 20%(by weight) for Metakaolin. The various results, which indicate the effect of replacement of cement by metakalion on concrete, are presented in this paper to draw useful conclusions.

  8. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    Directory of Open Access Journals (Sweden)

    Lei Gao

    2015-01-01

    Full Text Available In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net.

  9. Advanced high strength steels for automotive industry

    Directory of Open Access Journals (Sweden)

    Galán, J.

    2012-04-01

    Full Text Available The car industry is facing pressure because of the growing demand for more fuel-efficient passenger cars. In order to limit energy consumption and air pollution the weight of the carbody has to be reduced. At the same time, high levels of safety have to be guaranteed. In this situation, the choice of material becomes a key decision in car design. As a response to the requirements of the automotive sector, high strength steels and advanced high strength steels have been developed by the steel industry. These modern steel grades offer an excellent balance of low cost, light weight and mechanical properties.

    La industria del automóvil se enfrenta a una creciente demanda de vehículos de pasajeros más eficientes. Con el fin de disminuir el consumo de energía y la contaminación ambiental, el peso del vehículo tiene que ser reducido, al mismo tiempo que se garantizan altos niveles de seguridad. Ante esta situación, la elección de material se convierte en una decisión crucial en el diseño del vehículo. Como respuesta a las necesidades del sector automovilístico, nuevos aceros avanzados y de alta resistencia, han sido desarrollados por la industria siderúrgica. Dichos tipos de acero ofrecen un excelente equilibrio de precio, peso y propiedades mecánicas.

  10. Relationship between Leucite Content and Compressive Strength of K2O-Al2O3-SiO2 System Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; QIAN Fatang; DUAN Xinglong; WU Bolin

    2009-01-01

    Relationship between leucite content and compressive strength of K2O-Al2O3-SiO2 sys-tem dental glass ceramics were investigated. 10 groups of feedstock powder with different composi-tions were treated according to the same thermal treatment system of leucite micro-crystallization reported in some primary studies. The products of each group were analyzed by X-ray diffractometer,polaring microscope and scanning electronic microscope (SEM), and then the compressive strength was tested by a material testing machine. A direct proportion was found between leucite content and the compressive strength when leucite content was less than 50 vol%, and compressive strength de-creased with the increasing of leucite micro-crystals when leucite content was more than 50vol%, The leucite content has a notable influence on the compressive strength of K2O-Al2O3-SiO2 system dental glass ceramics.

  11. Investigation of compressive membrane action in ultra high performance concrete slab strips

    Science.gov (United States)

    Foust, Bradley Wade

    Reinforced concrete slabs are found in very common structural systems in both civilian and military applications. The boundary conditions that support the slab play an important role in the response to a particular load. Specifically, the amount of lateral and rotational restraint dictates how a slab responds to a particular load. Compressive membrane (i.e., in-plane) forces are present in slabs when the boundaries are sufficiently stiff, therefore restricting the slab from both lateral translations and rotations. Advancements have been made to account for the additional capacity due to compressive membrane forces in conventional strength concrete. In today's world, concrete performance is improving because of increasing compressive strengths and additional ductility present in concrete members. As a result of this current improvement, there is an urgent need to investigate compressive membrane theory in ultra-high-performance concrete (UHPC) slabs to better understand their behavior. Existing compressive membrane theory should be revisited to determine if current theory is applicable, or if it is not, what modifications should be made. This study will provide insight into the validity of existing theory that is currently used to predict the ultimate capacity in conventional-strength concrete slabs and attempt to modify the existing equations to account for high-strength concrete materials. A matrix of 14 normal-strength concrete (NSC) and 13 UHPC slabs was tested both statically and dynamically to better understand the behavior of each material set and the effects that boundary conditions have on slab response. The results from these experiments were then compared to response calculations made from existing theory as well as finite element analyses. Valuable data sets on rigidly restrained UHPC slab response were obtained through an experimental research program. The experiments helped to validate the associated numerical analysis that was performed. It was

  12. Effect of niobium and carbon on microstructure and compressive yield strength of as cast ESR Fe-8.5Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baligidad, R.G.; Dutta, A.; Rao, A.S.

    2005-03-15

    The effect of niobium (1.5 and 3.5 wt-%) addition on the microstructure and mechanical properties of as cast ESR Fe-8.5Al-0.1C alloy has been studied. Alloys were prepared by a combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR). As cast ESR alloys were characterised using an optical microscope, a scanning electron microscope (SEM) and an electron probe microanalyser (EPMA). Compression tests were carried out on as cast ESR alloy samples at temperatures up to 800{sup o}C. Addition of 1.5 wt-% Nb to Fe-8.5Al-0.1C alloy resulted in a marginal improvement in the compressive yield strength at test temperatures up to 1073 K, whereas addition of 3.5 wt-% Nb significantly improved the strength. This significant improvement in the room and high temperature compressive strength may be attributed to solid solution strengthening as well as precipitation hardening by the presence of fine and higher volume fractions of niobium and niobium carbide precipitates, in contrast to the relatively soft Fe{sub 3}AlC{sub 0.5} precipitates present in the Fe-8.5Al-0.1C alloy. (author)

  13. Analysis of Environmental Impact for Concrete Using LCA by Varying the Recycling Components, the Compressive Strength and the Admixture Material Mixing

    Directory of Open Access Journals (Sweden)

    Taehyoung Kim

    2016-04-01

    Full Text Available Concrete is a type of construction material in which cement, aggregate, and admixture materials are mixed. When cement is produced, large amounts of substances that impact the environment are emitted during limestone extraction and clinker manufacturing. Additionally, the extraction of natural aggregate causes soil erosion and ecosystem destruction. Furthermore, in the process of transporting raw materials such as cement and aggregate to a concrete production company, and producing concrete in a batch plant, substances with an environmental impact are emitted into the air and water system due to energy use. Considering the fact that the process of producing concrete causes various environmental impacts, an assessment of various environmental impact categories is needed. This study used a life cycle assessment (LCA to evaluate the environmental impacts of concrete in terms of its global warming potential, acidification potential, eutrophication potential, ozone depletion potential, photochemical ozone creation potential, and abiotic depletion potential (GWP, AP, EP, ODP, POCP, ADP. The tendency was that the higher the strength of concrete, the higher the GWP, POCP, and ADP indices became, whereas the AP and EP indices became slightly lower. As the admixture mixing ratio of concrete increased, the GWP, AP, ODP, ADP, and POCP decreased, but EP index showed a tendency to increase slightly. Moreover, as the recycled aggregate mixing ratio of concrete increased, the AP, EP, ODP, and ADP decreased, while GWP and POCP increased. The GWP and POCP per unit compressed strength (1 MPa of high strength concrete were found to be about 13% lower than that for its normal strength concrete counterpart. Furthermore, in the case of AP, EP, ODP, and ADP per unit compressed strength (1 MPa, high-strength concrete was found to be about 10%~25% lower than its normal strength counterpart. Among all the environmental impact categories, ordinary cement was found to have

  14. [Evaluation of grip strength in normal and obese Wistar rats submitted to swimming with overload after median nerve compression].

    Science.gov (United States)

    Coradinia, Josinéia Gresele; Kakihata, Camila Mayumi Martin; Kunz, Regina Inês; Errero, Tatiane Kamada; Bonfleur, Maria Lúcia; Bertolini, Gladson Ricardo Flor

    2015-01-01

    To verify the functionality through muscle grip strength in animals with obesity induced by monosodium glutamate (MSG) and in control animals, which suffered compression of the right median nerve, and treated with swimming with overload. During the first five days of life, neonatal Wistar rats received subcutaneous injections of MSG. The control group received a hypertonic saline solution. Forty-eight rats were divided into six groups: G1 (control); G2 (control + injury); G3 (control + injury + swimming); G4 (obese); G5 (obese + injury); G6 (obese + injury + swimming). The animals in groups G2, G3, G5 and G6 were submitted to compression of the median nerve and G3 and G6 groups were treated, after injury, with swimming exercise with load for three weeks. The swimming exercise had a progressive duration, according to the week, of 20, 30 and 40minutes. Muscle strength was assessed using a grip strength meter preoperatively and on the 3rd, 7th, 14th and 21st days after surgery. The results were expressed and analyzed using descriptive and inferential statistics. When the grip strength was compared among assessments regardless of group, in the second assessment the animals exhibited lower grip strength. G1 and G4 groups had greater grip strength, compared to G2, G3, G4 and G6. The swimming exercise with overload has not been effective in promoting improvement in muscle grip strength after compression injury of the right median nerve in control and in obese-MSG rats. Copyright © 2013 Elsevier Editora Ltda. All rights reserved.

  15. Corner strength enhancement of high strength cold-formed steel at normal room and elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    Ju CHEN; Wei-liang JIN

    2008-01-01

    In this study,the suitability of current design methods for the 0.2% proof yield strength of the comer regions for high strength cold-formed steel at norrnal room temperature was investigated.The current standard predictions are generally accurate for outer comer specimen but conservative for inner comer specimen.Based on the experimental results,an analytical model to predict the comer strength of high strength cold-formed steel at normal room temperature was also proposed.The comparison indicated that the proposed model predicted well the comer strength of high strength cold-formed steel not only at normal room temperature but also at elevated temperatures.It is shown that the predictions obtained from the proposed model agree well with the test results.Generally the comer strength enhancement of high strength cold-formed steel decreases when the temperature increases.

  16. CO2 laser scribe of chemically strengthened glass with high surface compressive stress

    Science.gov (United States)

    Li, Xinghua; Vaddi, Butchi R.

    2011-03-01

    Chemically strengthened glass is finding increasing use in handheld, IT and TV cover glass applications. Chemically strengthened glass, particularly with high (>600MPa) compressive stress (CS) and deeper depth of layer (DOL), enable to retain higher strength after damage than non-strengthened glass when its surface is abraded. Corning Gorilla® Glass has particularly proven to be advantageous over competition in this attribute. However, due to high compressive stress (CS) and Central Tension (CT) cutting ion-exchanged glass is extremely difficult and often unmanageable where ever the applications require dicing the chemically strengthened mother glass into smaller parts. We at Corning have developed a CO2 laser scribe and break method (LSB) to separate a single chemically strengthened glass sheet into plurality of devices. Furthermore, CO2 laser scribe and break method enables debris-free separation of glass with high edge strength due to its mirror-like edge finish. We have investigated laser scribe and break of chemically strengthened glass with surface compressive stress greater than 600 MPa. In this paper we present the results of CO2 scribe and break method and underlying laser scribing mechanisms. We demonstrated cross-scribe repetitively on GEN 2 size chemically strengthened glass substrates. Specimens for edge strength measurements of different thickness and CS/DOL glass were prepared using the laser scribe and break technique. The specimens were tested using the standard 4-point bend method and the results are presented.

  17. Influence of Molarity and Chemical Composition on the Development of Compressive Strength in POFA Based Geopolymer Mortar

    Directory of Open Access Journals (Sweden)

    S. M. Alamgir Kabir

    2015-01-01

    Full Text Available The investigation concerns the use of the optimum mix proportion of two locally available pozzolanic waste materials, namely, ground granulated blast furnace slag (GGBS and palm oil fuel ash (POFA, together with metakaolin (MK as binders. In addition, another local waste material, manufactured sand (M-sand, was used as a replacement for conventional sand in the development of green geopolymer mortar. Twenty-four mortar mixtures were designed with varying binder contents and alkaline activators. The oven dry curing was also kept consistent for all the mix proportions at a temperature of 65°C for 24 hours. The highest 28-day compressive strength of about 48 MPa was obtained for the mortar containing 20% of MK, 35% of GGBS, and 45% of POFA. The increment of MK beyond 20% leads to reduction of the compressive strength. The GGBS replacement beyond 35% also reduced the compressive strength. The entire specimen achieved average 80% of the 28-day strength at the age of 3 days. The density decreased with the increase of POFA percentage. The finding of this research by using the combination of MK, GGBS, and POFA as binders to wholly replace conventional ordinary Portland cement would lead to alternate eco-friendly geopolymer matrix.

  18. Modeling compressive strength of recycled aggregate concrete by Artificial Neural Network, Model Tree and Non-linear Regression

    Directory of Open Access Journals (Sweden)

    Neela Deshpande

    2014-12-01

    Full Text Available In the recent past Artificial Neural Networks (ANN have emerged out as a promising technique for predicting compressive strength of concrete. In the present study back propagation was used to predict the 28 day compressive strength of recycled aggregate concrete (RAC along with two other data driven techniques namely Model Tree (MT and Non-linear Regression (NLR. Recycled aggregate is the current need of the hour owing to its environmental friendly aspect of re-use of the construction waste. The study observed that, prediction of 28 day compressive strength of RAC was done better by ANN than NLR and MT. The input parameters were cubic meter proportions of Cement, Natural fine aggregate, Natural coarse Aggregates, recycled aggregates, Admixture and Water (also called as raw data. The study also concluded that ANN performs better when non-dimensional parameters like Sand–Aggregate ratio, Water–total materials ratio, Aggregate–Cement ratio, Water–Cement ratio and Replacement ratio of natural aggregates by recycled aggregates, were used as additional input parameters. Study of each network developed using raw data and each non dimensional parameter facilitated in studying the impact of each parameter on the performance of the models developed using ANN, MT and NLR as well as performance of the ANN models developed with limited number of inputs. The results indicate that ANN learn from the examples and grasp the fundamental domain rules governing strength of concrete.

  19. Effect of Superplasticizer and Extra Water on Workability and Compressive Strength of Self-Compacting Geopolymer Concrete

    Directory of Open Access Journals (Sweden)

    Fareed Ahmed Memon

    2012-03-01

    Full Text Available This study documents the results of an experimental work carried out to investigate the effect of superplasticizer and amount of extra water on strength and workability properties of Fly ash-based Selfcompacting geopolymer concrete. The experiments were conducted by varying the amount of extra water and dosage of superplasticizer. A total of nine mixtures with superplasticizer content varying from 3 to 7% and extra water ranging from 10 to 20% of the mass of fly ash were prepared and tested. The essential workability properties of the freshly prepared concrete such as filling ability, passing ability and segregation resistance were evaluated by using Slump flow, T50 slump flow, V-funnel, L-box and J-ring test methods. The compressive strength tests were carried out at 1, 3, 7 and 28 days. Test results indicated that extra water and superplasticizer are key parameters and play an important role in the development of self-compacting geopolymer concrete. Workability of self-compacting geopolymer concrete was dependent on the amount of extra water and dosage of superplasticizer. With the increase in amount of extra water and superplasticizer, the workability was improved. However, the addition of water beyond 15% resulted in bleeding as well as segregation and decreased the compressive strength of the concrete. The compressive strength of self-compacting geopolymer concrete was significantly decreased as the amount of extra water exceeded 12% by mass of Fly ash.

  20. Influences of Short Discrete Fibers in High Strength Concrete with Very Coarse Sand

    Directory of Open Access Journals (Sweden)

    Mahyuddin Ramli

    2010-01-01

    Full Text Available Problem statement: High Strength Concrete (HSC normally content high cementitous amount and low water binder ratio. However, these would cause substantial volume changes to the concrete and therefore affected the strength development. In addition, the brittleness of HSC was increased when silica fume used as partial cement replacement to achieve high strength. Approach: This study discussed the effects of incorporated short discrete Coconut Fibers (CF, Barchip Fibers (BF and Glass Fibers (GF into HSC to enhance the performance of concrete while kept the binder content at moderate level. Additional specialty to this HSC was casted with very coarse sand with fineness modulus of 3.98. A total of thirteen mixes were casted and tested for slump, density, compressive strength, flexural strength and ultrasonic pulse velocity in accordance with British Standards. Results: The slump was slightly reduced by the short discrete fibers. All of the fibrous specimens had lower density than control. However, the compressive strength of the HSC had increased from 71.8-79.0 MPa using 1.8% of BF, while flexural strength had increased from 5.21-6.50 MPa. All specimens showed that ultrasonic velocity higher than 4.28 km sec-1. Conclusion/Recommendations: In short, combination of incorporated short discrete fibers and applied very coarse sand to produce HSC showed very satisfying results and improvements. Further assessment on durability and impact resistivity will be verified in the coming research.

  1. Experimental Study on Deterioration Concrete Strength Different Sub-high Temperature Cycles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Tests were carried out to study the strength deterioration of concrete cooled in air or by water after sub-high temperature at different level and varying with cycles. It is proved that the cross-shaped cracks turned up and extended little by little on the surface of specimen subjected to repeat sub-high temperature, the splitting failure is characterized by cross-shaped cracks after 30 cycles, the concrete strengths decrease rapidly at early stage and to be steady subsequently with the increase of the temperature cycles,the splitting-tensile strength is more sensitive to temperature cycles than the compressive strength, the decline of concrete strength is mainly controlled by the maximum temperature having reached, the ultrasonic velocity in concrete is also declined. On the basis of test results, the mechanisms of sub-high temperature to the strength deterioration of concrete are analyzed.The formulas for calculating the compressive and splitting-tensile strength of concrete relating to the variation of temperature are proposed.

  2. High Strength Wood-based Sandwich Panels Reinforced with Fiberglass and Foam

    Directory of Open Access Journals (Sweden)

    Jinghao Li

    2014-02-01

    Full Text Available Mechanical analysis is presented for new high-strength sandwich panels made from wood-based phenolic impregnated laminated paper assembled with an interlocking tri-axial ribbed core. Four different panel configurations were tested, including panels with fiberglass fabric bonded to both outside faces with self-expanding urethane foam used to fill the ribbed core. The mechanical behaviors of the sandwich panels were strength tested via flatwise compression, edgewise compression, and third-point load bending. Panels with fiberglass exhibited significantly increased strength and apparent MOE in edgewise compression and bending, but there were no noticeable effects in flatwise compression. The foam provided improved support that resisted both rib buckling and face buckling for both compression and bending tests. Post-failure observation indicated that core buckling dominated the failures for all configurations used. It is believed that using stiffer foam or optimizing the dimension of the core might further improve the mechanical performance of wood-based sandwich panels.

  3. Characteristic compression strength of a brickwork masonry starting from the strength of its components. Experimental verification of analitycal equations of european codes

    Directory of Open Access Journals (Sweden)

    Rolando, A.

    2006-09-01

    Full Text Available In this paper the compression strength of a clay brickwork masonry bound with cement mortar is analyzed. The target is to obtain the characteristic compression strength of unreinforced brickwork masonry. This research try to test the validity of the analytical equations in European codes, comparing the experimental strength with the analytically obtained from the strength of its components (clay brick and cement mortar.En este artículo se analiza la resistencia a compresión de una fábrica de ladrillo cerámico, asentado con mortero de cemento.El objetivo es obtener la resistencia característica a compresión de la fábrica sin armar.La investigación comprueba la fiabilidad de las expresiones analíticas existentes en la normativa europea, comparando la resistencia obtenida experimentalmente con la obtenida analíticamente, a partir de la resistencia de sus componentes (ladrillo cerámico y mortero de cemento.

  4. Spall strength and ejecta production of gold under explosively driven shock wave compression

    Energy Technology Data Exchange (ETDEWEB)

    La Lone, B. M. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Stevens, G. D. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Turley, W. D. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Veeser, L. R. [National Security Technologies, LLC. (NSTec), Mercury, NV (United States); Holtkamp, D. B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2013-12-16

    Explosively driven shock wave experiments were conducted to characterize the spall strength and ejecta production of high-purity cast gold samples. The samples were from 0.75 to 1.84 mm thick and 30 mm in diameter. Peak stresses up to 44 GPa in gold were generated using PBX-9501 high explosive. Sample free surface and ejecta velocities were recorded using photonic Doppler velocimetry techniques. Lithium niobate pins were used to quantify the time dependence of the ejecta density and the total ejected mass. An optical framing camera for time-resolved imaging and a single-image x-ray radiograph were used for additional characterization. Free surface velocities exhibited a range of spall strengths from 1.7 to 2.4 GPa (mean: 2.0 ±0.3 GPa). The pullback signals were faint, minimal ringing was observed in the velocity records, and the spall layer continued to decelerate after first pull back. These results suggest finite tensile strength was present for some time after the initial void formation. Ejecta were observed for every sample with a roughened free surface, and the ejecta density increased with increased surface roughness, which was different in every experiment. The total ejected mass is consistent with the missing mass model.

  5. Performance of High-Strength Concrete Using Palm Oil Fuel Ash as Partial Cement Replacement

    Directory of Open Access Journals (Sweden)

    Dr. M. Swaroopa Rani

    2015-04-01

    Full Text Available The advancement in material technology has led to development of concrete with higher strengths. Presence of high cementitious materials contents in high strength concrete mixes increases heat of hydration that causes higher shrinkage and leading it to potential of cracking. However, use of supplementary cementitious materials leads to control in heat of hydration which further avoids higher shrinkage. Materials such as fly ash, silica fume, metakaolin and ground granulated blast furnace slag are largely been used as supplementary cementitious materials in High strength concrete mixes. In the present study use of palm oil fuel ash (POFA as partial cement replacement in high strength concrete mixes is evaluated with an experimental study. High strength concrete mix of M60 grade is taken as a reference and the compressive strength, split tensile strength and flexural strength where performed for 7, 28 and 56 days and analyzed it with results for partial replacement mixes of POFA 5%, 10%, 15%, 20% & 25%. It has been observed that concrete with 15% replacement of POFA gave the highest strength.

  6. Creep Behavior of High-Strength Concrete Subjected to Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Minho Yoon

    2017-07-01

    Full Text Available Strain is generated in concrete subjected to elevated temperatures owing to the influence of factors such as thermal expansion and design load. Such strains resulting from elevated temperatures and load can significantly influence the stability of a structure during and after a fire. In addition, the lower the water-to-binder (W–B ratio and the smaller the quantity of aggregates in high-strength concrete, the more likely it is for unstable strain to occur. Hence, in this study, the compressive strength, elastic modulus, and creep behavior were evaluated at target temperatures of 100, 200, 300, 500, and 800 °C for high-strength concretes with W–B ratios of 30%, 26%, and 23%. The loading conditions were set as non-loading and 0.33fcu. It was found that as the compressive strength of the concrete increased, the mechanical characteristics deteriorated and transient creep increased. Furthermore, when the point at which creep strain occurred at elevated temperatures after the occurrence of transient creep was considered, greater shrinkage strain occurred as the compressive strength of the concrete increased. At a heating temperature of 800 °C, the 80 and 100 MPa test specimens showed creep failure within a shrinkage strain range similar to the strain at the maximum load.

  7. Creep Behavior of High-Strength Concrete Subjected to Elevated Temperatures.

    Science.gov (United States)

    Yoon, Minho; Kim, Gyuyong; Kim, Youngsun; Lee, Taegyu; Choe, Gyeongcheol; Hwang, Euichul; Nam, Jeongsoo

    2017-07-11

    Strain is generated in concrete subjected to elevated temperatures owing to the influence of factors such as thermal expansion and design load. Such strains resulting from elevated temperatures and load can significantly influence the stability of a structure during and after a fire. In addition, the lower the water-to-binder (W-B) ratio and the smaller the quantity of aggregates in high-strength concrete, the more likely it is for unstable strain to occur. Hence, in this study, the compressive strength, elastic modulus, and creep behavior were evaluated at target temperatures of 100, 200, 300, 500, and 800 °C for high-strength concretes with W-B ratios of 30%, 26%, and 23%. The loading conditions were set as non-loading and 0.33fcu. It was found that as the compressive strength of the concrete increased, the mechanical characteristics deteriorated and transient creep increased. Furthermore, when the point at which creep strain occurred at elevated temperatures after the occurrence of transient creep was considered, greater shrinkage strain occurred as the compressive strength of the concrete increased. At a heating temperature of 800 °C, the 80 and 100 MPa test specimens showed creep failure within a shrinkage strain range similar to the strain at the maximum load.

  8. Injectable porous nano-hydroxyapatite/chitosan/tripolyphosphate scaffolds with improved compressive strength for bone regeneration.

    Science.gov (United States)

    Uswatta, Suren P; Okeke, Israel U; Jayasuriya, Ambalangodage C

    2016-12-01

    In this study we have fabricated porous injectable spherical scaffolds using chitosan biopolymer, sodium tripolyphosphate (TPP) and nano-hydroxyapatite (nHA). TPP was primarily used as an ionic crosslinker to crosslink nHA/chitosan droplets. We hypothesized that incorporating nHA into chitosan could support osteoconduction by emulating the mineralized cortical bone structure, and improve the Ultimate Compressive Strength (UCS) of the scaffolds. We prepared chitosan solutions with 0.5%, 1% and 2% (w/v) nHA concentration and used simple coacervation and lyophilization techniques to obtain spherical scaffolds. Lyophilized spherical scaffolds had a mean diameter of 1.33mm (n=25). Further, portion from each group lyophilized scaffolds were soaked and dried to obtain Lyophilized Soaked and Dried (LSD) scaffolds. LSD scaffolds had a mean diameter of 0.93mm (n=25) which is promising property for the injectability. Scanning Electron Microscopy images showed porous surface morphology and interconnected pore structures inside the scaffolds. Lyophilized and LSD scaffolds had surface pores chitosan LSD scaffolds exhibited UCS of 8.59MPa compared to UCS of 2% nHA/chitosan lyophilized scaffolds at 3.93MPa. Standardize UCS values were 79.98MPa and 357MPa for 2% nHA/chitosan lyophilized and LSD particles respectively. One-way ANOVA results showed a significant increase (pchitosan lyophilized scaffolds compared to 0% and 0.5% nHA/chitosan lyophilized scaffolds. Moreover, 2% nHA LSD scaffolds had significantly increased (pchitosan scaffolds showed higher osteoblast attachment than 0% nHA/chitosan scaffolds. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Estimation of compressive strength based on Pull-Out bond test results for on-site concrete quality control

    Directory of Open Access Journals (Sweden)

    M. S. Lorrain

    Full Text Available Quality control of structural concrete has been conducted for several decades based mainly on the results of axial compression tests. This kind of test, although widely used, is not exempt from errors and has some considerable drawbacks that may affect its reliability, such as the need for appropriate and careful specimen conditioning and adoption of adequate capping techniques. For these reasons, it would be useful to have complementary or alternative ways to check compressive strength, in order to improve concrete quality control. The use of a bond test to monitor concrete strength is being proposed by an international group of researchers from France, Tunisia and Brazil as a potential means to this end. Given the fact that the link between bond resistance and concrete strength is already well established, this type of test seems to be a viable alternative to traditional methods. Nonetheless, to check if the underlying principle is sound when used in different circumstances, the group has been gathering data from several studies conducted by different researchers in various countries, with distinct concretes and rebar types. An analysis of the data collected shows that there is a clear and strong correlation between bond resistance and compressive strength, no matter the influence of other variables. This result validates the basic idea of using an Appropriate Pull-Out (APULOT bond test to assess concrete strength. If the general principle is valid for random data obtained from different studies, the definition of a clear and appropriate test will probably lead to the reduction of experimental noise and increase the precision of the strength estimates obtained using this method.

  10. High strength air-dried aerogels

    Science.gov (United States)

    Coronado, Paul R.; Satcher, Jr., Joe H.

    2012-11-06

    A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

  11. Effect of Coal Gangue with Different Kaolin Contents on Compressive Strength and Pore Size of Blended Cement Paste

    Institute of Scientific and Technical Information of China (English)

    CHEN Yimin; ZHOU Shuangxi; ZHANG Wensheng

    2008-01-01

    The effects of activated coal gangue on compressive strength,porosity and pore size distribution of hardened cement pastes were investigated.Activated coal gangue with two different kaolin contents,one higher and one lower,were used to partially replace Portland cement at 0%,10%,and 30% by weight.The water to binder ratio(w/b)of 0.5 was used for all the blended cement paste mixes.Experimental results indicate that the blended cement of activated coal gangue mortar with higher kaolin mineral content has a higher compressive strength than that with lower kaolin mineral content.The porosity and pore size of blended cement mortar were significantly affected by the replacement of activated coal gangue.

  12. Fatigue strength of welded connections made of very high strength cast and rolled steels

    NARCIS (Netherlands)

    Pijpers, R.J.M.

    2011-01-01

    Although Very High Strength Steels (VHSS) with nominal strengths up to 1100 MPa have been available on the market for many years, the use of these steels in the civil engineering industry is still uncommon. The main objective of the research is the determination of the fatigue strength of welded con

  13. Comparison of the weathering behavior of a very high strength concrete with that of a standard concrete

    OpenAIRE

    A. Blandine; B. Essaïd; Bernard, G.

    2008-01-01

    We studied the weathering process of a very high strength concrete (VHSC) and compared it with that of a usual concrete. VHSC has compressive strengths much above 100 MPa after seven days of curing. The compressive strength is increased by lowering the value of the water/cement ratio and by improving the particle size distribution of the numerous residual anhydrous grains of clinker and of the quartz aggregates. A proportion of 15% of the cement is replaced by non-condensed silica fume, which...

  14. Multicriteria decision-making analysis based methodology for predicting carbonate rocks' uniaxial compressive strength

    Directory of Open Access Journals (Sweden)

    Ersoy Hakan

    2012-10-01

    Full Text Available

    ABSTRACT

    Uniaxial compressive strength (UCS deals with materials' to ability to withstand axially-directed pushing forces and especially considered to be rock materials' most important mechanical properties. However, the UCS test is an expensive, very time-consuming test to perform in the laboratory and requires high-quality core samples having regular geometry. Empirical equations were thus proposed for predicting UCS as a function of rocks' index properties. Analytical hierarchy process and multiple regression analysis based methodology were used (as opposed to traditional linear regression methods on data-sets obtained from carbonate rocks in NE Turkey. Limestone samples ranging from Devonian to late Cretaceous ages were chosen; travertine-onyx samples were selected from morphological environments considering their surface environmental conditions Test results from experiments carried out on about 250 carbonate rock samples were used in deriving the model. While the hierarchy model focused on determining the most important index properties affecting on UCS, regression analysis established meaningful relationships between UCS and index properties; 0. 85 and 0. 83 positive coefficient correlations between the variables were determined by regression analysis. The methodology provided an appropriate alternative to quantitative estimation of UCS and avoided the need for tedious and time consuming laboratory testing


    RESUMEN

    La resistencia a la compresión uniaxial (RCU trata con la capacidad de los materiales para soportar fuerzas empujantes dirigidas axialmente y, especialmente, es considerada ser uno de las más importantes propiedades mecánicas de

  15. Study of Compressive Strength of Concrete with Coal Power Plant Fly Ash as Partial Replacement of Cement and Fine Aggregate

    Directory of Open Access Journals (Sweden)

    FAREED AHMED MEMON

    2010-10-01

    Full Text Available This research study comprises of concrete cubes made with Ordinary Portland Cement and with different configurations of fly ash by replacing cement and fine aggregate. To achieve the aim of this study, total 81 concrete cubes were cast. Among 81 cubes, 9 cubes were made with normal concrete, 36 cubes were made by replacing 25%, 50%, 75% and 100% of fine aggregate with fly ash and 36 cubes were made by replacing 10%, 25%, 50%, and 75% of cement with fly ash. The cubes were 6\\" x 6\\" in cross-section, and the mix design was aimed for 5000 psi. After proper curing of all 81 cubes, they were tested at 3, 7 and 28 days curing age. The cubes were tested in Forney Universal Testing Machine. By analyzing the test results of all the concrete cubes, the following main findings have been drawn. The compressive strength of concrete cubes made by replacing 100 % fine aggregate by fly ash was higher than the concrete cubes made with Ordinary Portland Cement at all 3, 7 and 28 days curing ages. On the other hand, the compressive strength of concrete cubes made by replacing 10 % and 25 % cement by fly ash was slightly lower than the concrete cubes made with Ordinary Portland Cement at all curing ages, whereas, the compressive strength of concrete cubes made by replacing 50 % and 75 % of cement by fly ash were quite lower than the concrete cubes made with Ordinary Portland Cement at all curing ages.

  16. Effects of carbonation on the leachability and compressive strength of cement-solidified and geopolymer-solidified synthetic metal wastes.

    Science.gov (United States)

    Pandey, Bhishan; Kinrade, Stephen D; Catalan, Lionel J J

    2012-06-30

    The effects of accelerated carbonation on the compressive strength and leachability of fly ash-based geopolymer and ordinary portland cement (OPC) doped with Cd(II), Cr(III), Cr(VI), Cu(II), Pb(II) or Zn(II) salts were investigated. Cement was effective at immobilizing Cd, Cr(III), Cu, Pb and Zn under both the Synthetic Precipitation Leaching Procedure (SPLP) and the Toxicity Characteristic Leaching Procedure (TCLP), but ineffective for retaining Cr(VI). Carbonated cement maintained its ability to immobilize Cd, Cr(III), Pb and Zn, but, under acidic TCLP conditions, was much worse at retaining Cu. Geopolymer was effective at immobilizing Cr(III) and Cu, and, to a lesser degree, Cd, Pb and Zn in SPLP leaching tests. Only Cr(III) was immobilized under comparatively acidic TCLP testing conditions. Carbonation did not change the metal retention capacity of the geopolymer matrix. Metal doping caused compressive strengths of both geopolymer and cement to decrease. Carbonation increased the compressive strength of cement, but decreased that of the geopolymer. Geochemical equilibrium modeling provided insight on the mechanisms of metal immobilization.

  17. Effect of Elevated Temperature and Aggressive Chemical Environment on Compressive Strength of M-30 Grade of Concrete Composite.

    Directory of Open Access Journals (Sweden)

    Chandan Kumar

    2014-05-01

    Full Text Available The present paper reports result of an experimental program conducted to study the behavior of M-30 grade of concrete at elevated temperature on the basis of physical appearance, weight loss and residual compressive strength test. The concrete cubes(M-30 of 150×150×150 mm were cast with a ratio of 1:1.26:2.8 by weight. Three cubeswere tested for compressive strength at the age of 7 days and 28 days by universal testing machine. Then the specimen were subjected to the elevated temperature 200o c, 400o c, 600o c, 800o c and 1000o c in an electric air heated muffle and after cooling were tested for the compressive strength. Six cubes were immersed in each solution of sodium sulphate, sulfuric acid, and sodium chloride for 30 days and 60 days. The testreveal the properties of M-30 concrete and its applicability at elevated temperature and against aggressive environment such as acid attack, sulphate attack and chloride attack. Keywords:

  18. The high-pressure compressibility of B12P2

    Science.gov (United States)

    Gao, Yang; Zhou, Mi; Wang, Haiyan; Ji, Cheng; Whiteley, C. E.; Edgar, J. H.; Liu, Haozhe; Ma, Yanzhang

    2017-03-01

    In situ high pressure synchrotron X-ray diffraction measurements were performed on icosahedral boron phosphide (B12P2) to 43.2 GPa. No structural phase transition occurs over this pressure range. The bulk modulus of B12P2 is KOT = 207 ± 7 GPa with pressure derivative of K'OT = 6.6 ± 0.8 . The structure is most compressible along the chain formed by phosphorus and boron atoms in the crystal structure. It is believed that the compressibility of boron-rich compounds at close to ambient pressure is determined by the boron icosahedral structure, while the inclusive atoms (both boron and non-boron) between the icosahedra determine the high-pressure compressibility and structure stability.

  19. Development and Performance Evaluation of Very High Early Strength Geopolymer for Rapid Road Repair

    Directory of Open Access Journals (Sweden)

    Abideng Hawa

    2013-01-01

    Full Text Available High early strength is the most important property of pavement repair materials to allow quick reopening to traffic. With this in mind, we have experimentally investigated geopolymers using low cost raw materials available in Thailand. The geopolymer mortar was metakaolin (MK, mixed with parawood ash (PWA, rubberwood ash or oil palm ash (OPA as binder agent. Rubberwood is often used as raw material for biomass power plants in Thailand, especially at latex glove factories and seafood factories, and burning rubberwood generates PWA. Both PWA and OPA are therefore low cost residual waste, locally available in mass quantities. The geopolymer samples were characterized for compressive strength, drying shrinkage, and bond strength to Portland cement mortar with slant shear test. The experimental design varied the contents of PWA and OPA and the heat curing time (1, 2 and 4 h after hot mixture process. The hot mixture process resulted in very high early strength. In addition, we achieved high compressive strengths, low drying shrinkage, and very significant bond strength enhancement by use of the ashes.

  20. The Structure and Mechanical Properties of High-Strength Bulk Ultrafine-Grained Cobalt Prepared Using High-Energy Ball Milling in Combination with Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Ivo Marek

    2016-05-01

    Full Text Available In this study, bulk ultrafine-grained and micro-crystalline cobalt was prepared using a combination of high-energy ball milling and subsequent spark plasma sintering. The average grain sizes of the ultrafine-grained and micro-crystalline materials were 200 nm and 1 μm, respectively. Mechanical properties such as the compressive yield strength, the ultimate compressive strength, the maximum compressive deformation and the Vickers hardness were studied and compared with those of a coarse-grained as-cast cobalt reference sample. The bulk ultrafine-grained sample showed an ultra-high compressive yield strength that was greater than 1 GPa, which is discussed with respect to the preparation technique and a structural investigation.

  1. Durability and Strength Properties on High Performance Self Compacting Concrete with GGBS and Silica Fumes

    Directory of Open Access Journals (Sweden)

    J. M.Srishaila

    2014-06-01

    Full Text Available This study on the experimental investigation on strength aspects like compressive strength, flexural strength and split tensile strength, and durability aspects like rapid chloride penetration test(RCPT of high performance self-compacting concrete with different mineral admixtures . Initials tests like slump test, L-box test, U-box test and T50 test will be carried out. The methodology adopted here is Ground granulated blast furnace slag (GGBS which is replaced partially by cement at 10%, 20% and 30% and silica fumes(SF by 3%, 6%, 9% in combination with Portland cement and the performance is measured and compared. The influence of mineral admixtures on the workability, mechanical strength and durability aspects of self-compacting concrete are studied. The mix proportion is obtained as per the guidelines given by European Federation of producers and contractors of special products for structure.

  2. Technical Note: Filler and superplasticizer usage on high strength concrete

    Directory of Open Access Journals (Sweden)

    Sümer, M.

    2007-08-01

    Full Text Available In this research, the effects of filler (rock-dust usage on high strength concrete have been investigated through lab experiments and some results have been obtained. The experiments involved three series of concrete with different cement proportions of 375 kg/m3, 400 kg/m3, and 425 kg/m3. For each series of concrete, three different groups of samples have been prepared, the first one being the reference concrete which contained 0% chemical admixture and 0% filler, the second one contained 1.5% chemical admixture and 0% filler and finally the last group contained 1.5% chemical admixture and 5% filler to the weight of cement used. The chemical admixture used was a type of Super plasticizer with a brand name of “DARACEM 190”, and the cement used was Ordinary Portland Cement of target compressive strength 42.5 N/mm2, obtained from Nuh Cement Plant. For each batch, Slump Tests and Unit Weight Tests were performed. For each stage and group, two 15 cm cubic samples have been tested for Compressive Strength after being cured in water at 20 ± 2 °C for ages of 3 days, 7 days, 28 and 60 days. The total number of samples was 72. As a result, filler usage was found to reduce the porosity of Concrete, increase the Unit Weight of Concrete, increase the need for water and improve the Compressive Strength Properties of Concrete.En el presente trabajo se estudia la influencia de la utilización de un “filler” (polvo mineral en el comportamiento del hormigón de altas prestaciones. Para ello, se realizan ensayos de laboratorio en los que se emplean tres series de hormigón, cada una con una dosificación de cemento distinta, de 375, 400 y 425 kg/m3. Se preparan tres grupos de probetas de cada serie, el primero o de referencia con 0% de aditivo químico y 0% de “filler”, el segundo con un 1,5% del aditivo químico y 0% de “filler” y el tercero con un 1,5% del aditivo químico y un 5% de “filler” en peso del cemento. Como aditivo se

  3. Strength analysis of laser welded lap joint for ultra high strength steel

    Science.gov (United States)

    Jeong, Young Cheol; Kim, Cheol Hee; Cho, Young Tae; Jung, Yoon Gyo

    2013-12-01

    Several industries including the automotive industry have recently applied the process of welding high strength steel. High strength steel is steel that is harder than normal high strength steel, making it much stronger and stiffer. HSS can be formed in pieces that can be up to 10 to 15 percent thinner than normal steel without sacrificing strength, which enables weight reduction and improved fuel economy. Furthermore, HSS can be formed into complex shapes that can be welded into structural areas. This study is based on previous experiments and is aimed at establishing the stress distribution for laser welded high strength steel. Research on the stress distribution for laser welded high strength steel is conducted by using Solid Works, a program that analyzes the stress of a virtual model. In conclusion, we found that the stress distribution is changed depending on the shape of welded lap joint. In addition, the Influence of the stress distribution on welded high strength steel can be used to standard for high energy welding of high strength steel, and we can also predict the region in welded high strength steel that may cracked.

  4. Behavior of steel fiber-reinforced high-strength concrete at medium strain rate

    Institute of Scientific and Technical Information of China (English)

    Chujie JIAO; Wei SUN; Shi HUAN; Guoping JIANG

    2009-01-01

    Impact compression experiments for the steel fiber-reinforced high-strength concrete (SFRHSC) at medium strain rate were conducted using the split Hopkinson press bar (SHPB) testing method. The volume fractions of steel fibers of SFRHSC were between 0 and 3%. The experimental results showed that, when the strain rate increased from threshold value to 90 s-1, the maximum stress of SFRHSC increased about 30%, the elastic modulus of SFRHSC increased about 50%, and the increase in the peak strain of SFRHSC was 2-3 times of that in the matrix specimen. The strength and toughness of the matrix were improved remarkably because of the superposition effect of the aggregate high-strength matrix and steel fiber high-strength matrix. As a result, under impact loading, cracks developed in the SFRHSC specimen, but the overall shape of the specimen remained virtually unchanged. However, under similar impact loading, the matrix specimens were almost broken into small pieces.

  5. Study of recycled concrete aggregate quality and its relationship with recycled concrete compressive strength using database analysis

    Directory of Open Access Journals (Sweden)

    González-Taboada, I.

    2016-09-01

    Full Text Available This work studies the physical and mechanical properties of recycled concrete aggregate (recycled aggregate from concrete waste and their influence in structural recycled concrete compressive strength. For said purpose, a database has been developed with the experimental results of 152 works selected from over 250 international references. The processed database results indicate that the most sensitive properties of recycled aggregate quality are density and absorption. Moreover, the study analyses how the recycled aggregate (both percentage and quality and the mixing procedure (pre-soaking or adding extra water influence the recycled concrete strength of different categories (high or low water to cement ratios. When recycled aggregate absorption is low (under 5%, pre-soaking or adding extra water to avoid loss in workability will negatively affect concrete strength (due to the bleeding effect, whereas with high water absorption this does not occur and both of the aforementioned correcting methods can be accurately employed.El estudio analiza las propiedades físico-mecánicas de los áridos reciclados de hormigón (procedentes de residuos de hormigón y su influencia en la resistencia a compresión del hormigón reciclado estructural. Para ello se ha desarrollado una base de datos con resultados de 152 trabajos seleccionados a partir de más de 250 referencias internacionales. Los resultados del tratamiento de la base indican que densidad y absorción son las propiedades más sensibles a la calidad del árido reciclado. Además, este estudio analiza cómo el árido reciclado (porcentaje y calidad y el procedimiento de mezcla (presaturación o adición de agua extra influyen en la resistencia del hormigón reciclado de diferentes categorías (alta o baja relación agua-cemento. Cuando la absorción es baja (inferior al 5% presaturar o añadir agua para evitar pérdidas de trabajabilidad afectan negativamente a la resistencia (debido al bleeding

  6. Static compressive strength prediction of open-hole structure based on non-linear shear behavior and micro-mechanics

    Science.gov (United States)

    Li, Wangnan; Cai, Hongneng; Li, Chao

    2014-11-01

    This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.

  7. Effects of Nanosilica on Compressive Strength and Durability Properties of Concrete with Different Water to Binder Ratios

    Directory of Open Access Journals (Sweden)

    Forood Torabian Isfahani

    2016-01-01

    Full Text Available The effects of the addition of different nanosilica dosages (0.5%, 1%, and 1.5% with respect to cement on compressive strength and durability properties of concrete with water/binder ratios 0.65, 0.55, and 0.5 were investigated. Water sorptivity, apparent chloride diffusion coefficient, electrical resistivity, and carbonation coefficient of concrete were measured. The results showed that compressive strength significantly improved in case of water/binder = 0.65, while for water/binder = 0.5 no change was found. Increasing nanosilica content, the water sorptivity decreased only for water/binder = 0.55. The addition of 0.5% nanosilica decreased the apparent chloride diffusion coefficient for water/binder = 0.65 and 0.55; however, higher nanosilica dosages did not decrease it with respect to reference value. The resistivity was elevated by 0.5% nanosilica for all water/binder ratios and by 1.5% nanosilica only for water/binder = 0.5. The carbonation coefficient was not notably affected by increasing nanosilica dosages and even adverse effect was observed for water/binder = 0.65. Further information of microstructure was also provided through characterization techniques such as X-ray diffraction, thermal gravimetric analysis, mercury intrusion porosimetry, and scanning electron microscopy. The effectiveness of a certain nanosilica dosage addition into lower strength mixes was more noticeable, while, for the higher strength mix, the effectiveness was less.

  8. Aluminum/steel wire composite plates exhibit high tensile strength

    Science.gov (United States)

    1966-01-01

    Composite plate of fine steel wires imbedded in an aluminum alloy matrix results in a lightweight material with high tensile strength. Plates have been prepared having the strength of titanium with only 85 percent of its density.

  9. A compression scheme for radio data in high performance computing

    CERN Document Server

    Masui, Kiyoshi; Connor, Liam; Deng, Meiling; Fandino, Mateus; Höfer, Carolin; Halpern, Mark; Hanna, David; Hincks, Adam D; Hinshaw, Gary; Parra, Juan Mena; Newburgh, Laura B; Shaw, J Richard; Vanderlinde, Keith

    2015-01-01

    We present a procedure for efficiently compressing astronomical radio data for high performance applications. Integrated, post-correlation data are first passed through a nearly lossless rounding step which compares the precision of the data to a generalized and calibration-independent form of the radiometer equation. This allows the precision of the data to be reduced in a way that has an insignificant impact on the data. The newly developed Bitshuffle lossless compression algorithm is subsequently applied. When the algorithm is used in conjunction with the HDF5 library and data format, data produced by the CHIME Pathfinder telescope is compressed to 28% of its original size and decompression throughputs in excess of 1 GB/s are obtained on a single core.

  10. Compressive strength behaviour of low- and medium-strength concrete specimens confined with carbon fibres in defective implementation conditions: an experimental study

    Directory of Open Access Journals (Sweden)

    M. Fernández-Cánovas

    2016-10-01

    Full Text Available This behaviour of low- and medium-strength concrete specimens confined with carbon fibre-reinforced polymer (CFRP was analysed in three loading cycles. In some cases, stress levels were achieved that produced intemal microcracks, which allowed residual rigidity and the behaviour of completely microcraked concrete specimens to be studied. The specimens were subsequently tested to compression to the fracture point. Specimens reinforced in accordance with no manufacturing defects (100% CFRP reinforcement and major manufacturing defects (50% CFRP reinforcement were assessed for effectiveness and behaviour of the confined elements in less than ideal conditions. Results show that confinement was higher in low-resistance concretes, that the behaviour of reinforced specimens was unaffected by defective implementation conditions and that the reinforced specimens were less rigid than the non-reinforced specimens when tested up to 40% of ultimate fracture strength.

  11. High Strength, Weldable Precipitation Aged Steels

    Science.gov (United States)

    Wilson, Alexander D.

    1987-03-01

    The family of plate steels represented by ASTM Specification A7101 is finding increasing applications. These low carbon, Cu-Ni-Cr-Mo-Cb, copper precipitation hardened steels have been identified by a number of designations over the years. During early development in the late 1960's and first commercial production in 1970, the steels were known as IN-787 (trademark of International Nickel Company).2 ASTM specifications were subsequently developed for structural (A710) and pressure vessel (A736) applications over ten years ago. More recent interest and application of this family of steels by the U.S. Navy has lead to development of a military specification MIL-S-24645 (SH),3 also initially known as "HSLA-80." Significant tonnage is being produced for the U.S. Navy as a replacement for HY80 (MIL-S-16216) in cruiser deck, bulkhead and hull applications.4 In these applications, the enhanced weldability and requirement of no preheat at this high strength and toughness level has been the main motivation for its use. Over the past 15 years, A710 type steels have also been used in a variety of applications, including off-shore platforms, pressure vessels, arctic linepipe valves and off-highway mining truck frames.

  12. Advanced Gear Alloys for Ultra High Strength Applications

    Science.gov (United States)

    Shen, Tony; Krantz, Timothy; Sebastian, Jason

    2011-01-01

    Single tooth bending fatigue (STBF) test data of UHS Ferrium C61 and C64 alloys are presented in comparison with historical test data of conventional gear steels (9310 and Pyrowear 53) with comparable statistical analysis methods. Pitting and scoring tests of C61 and C64 are works in progress. Boeing statistical analysis of STBF test data for the four gear steels (C61, C64, 9310 and Pyrowear 53) indicates that the UHS grades exhibit increases in fatigue strength in the low cycle fatigue (LCF) regime. In the high cycle fatigue (HCF) regime, the UHS steels exhibit better mean fatigue strength endurance limit behavior (particularly as compared to Pyrowear 53). However, due to considerable scatter in the UHS test data, the anticipated overall benefits of the UHS grades in bending fatigue have not been fully demonstrated. Based on all the test data and on Boeing s analysis, C61 has been selected by Boeing as the gear steel for the final ERDS demonstrator test gearboxes. In terms of potential follow-up work, detailed physics-based, micromechanical analysis and modeling of the fatigue data would allow for a better understanding of the causes of the experimental scatter, and of the transition from high-stress LCF (surface-dominated) to low-stress HCF (subsurface-dominated) fatigue failure. Additional STBF test data and failure analysis work, particularly in the HCF regime and around the endurance limit stress, could allow for better statistical confidence and could reduce the observed effects of experimental test scatter. Finally, the need for further optimization of the residual compressive stress profiles of the UHS steels (resulting from carburization and peening) is noted, particularly for the case of the higher hardness C64 material.

  13. Progress at SLAC on high-power rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Nantista, C.; Ruth, R.D. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Kroll, N.M. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)]|[California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics

    1992-06-01

    Rf pulse compression is a technique for augmenting the peak power output of a klystron (typically 50--100 MW) to obtain the high peak power required to drive a linear collider at a high accelerating gradient (typically 200 MW/m is required for a gradient of 100 MV/m). The SLED pulse compression system, with a power gain of about 2.6, has been operational on the SLAC linac for more than a decade. Recently, a binary pulse-compression system with a power gain of about 5.2 has been tested up to an output power of 120 MW. Further high-power tests are in progress. Our current effort is focused on prototyping a so-called SLED-II pulse-compression system with a power gain of four. Over-moded TE{sub 01}-mode circular waveguide components, some with novel technical features, are used to reduce losses at the 11.4-GHz operating frequency.

  14. Progress at SLAC on high-power rf pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, P.B.; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Nantista, C.; Ruth, R.D. (Stanford Linear Accelerator Center, Menlo Park, CA (United States)); Kroll, N.M. (Stanford Linear Accelerator Center, Menlo Park, CA (United States) California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics)

    1992-06-01

    Rf pulse compression is a technique for augmenting the peak power output of a klystron (typically 50--100 MW) to obtain the high peak power required to drive a linear collider at a high accelerating gradient (typically 200 MW/m is required for a gradient of 100 MV/m). The SLED pulse compression system, with a power gain of about 2.6, has been operational on the SLAC linac for more than a decade. Recently, a binary pulse-compression system with a power gain of about 5.2 has been tested up to an output power of 120 MW. Further high-power tests are in progress. Our current effort is focused on prototyping a so-called SLED-II pulse-compression system with a power gain of four. Over-moded TE[sub 01]-mode circular waveguide components, some with novel technical features, are used to reduce losses at the 11.4-GHz operating frequency.

  15. The influence of poly(acrylic) acid number average molecular weight and concentration in solution on the compressive fracture strength and modulus of a glass-ionomer restorative.

    LENUS (Irish Health Repository)

    Dowling, Adam H

    2011-06-01

    The aim was to investigate the influence of number average molecular weight and concentration of the poly(acrylic) acid (PAA) liquid constituent of a GI restorative on the compressive fracture strength (σ) and modulus (E).

  16. Prediction of Compressive Strength of Self compacting Concrete with Flyash and Rice Husk Ash using Adaptive Neuro-fuzzy Inference System

    Directory of Open Access Journals (Sweden)

    S. S, Pathak

    2012-10-01

    Full Text Available Self-compacting concrete is an innovative concrete that 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 congested reinforcement without segregation and bleeding. In the present study self compacting concrete mixes were developed using blend of fly ash and rice husk ash. Fresh properties of theses mixes were tested by using standards recommended by EFNARC (European Federation for Specialist Construction Chemicals and Concrete system. Compressive strength at 28 days was obtained for these mixes. This paper presents development of Adaptive Neuro-fuzzy Inference System (ANFIS model for predicting compressive strength of self compacting concrete using fly ash and rice husk ash. The input parameters used for model are cement, fly ash, rice husk ash and water content. Output parameter is compressive strength at 28 days. The results show that the implemented model is good at predicting compressive strength.

  17. High Strain Rate Compressive Behavior of Polyurethane Resin and Polyurethane/Al2O3 Hollow Sphere Syntactic Foams

    Directory of Open Access Journals (Sweden)

    Dung D. Luong

    2014-01-01

    Full Text Available Polyurethane resins and foams are finding extensive applications. Seat cushions and covers in automobiles are examples of these materials. In the present work, hollow alumina particles are used as fillers in polyurethane resin to develop closed-cell syntactic foams. The fabricated syntactic foams are tested for compressive properties at quasistatic and high strain rates. Strain rate sensitivity is an important concern for automotive applications due to the possibility of crash at high speeds. Both the polyurethane resin and the syntactic foam show strain rate sensitivity in compressive strength. It is observed that the compressive strength increases with strain rate. The energy absorbed up to 10% strain in the quasistatic regime is 400% higher for the syntactic foam in comparison to that of neat resin at the same strain rate.

  18. Gaseous hydrogen embrittlement of high strength steels

    Science.gov (United States)

    Gangloff, R. P.; Wei, R. P.

    1977-01-01

    The effects of temperature, hydrogen pressure, stress intensity, and yield strength on the kinetics of gaseous hydrogen assisted crack propagation in 18Ni maraging steels were investigated experimentally. It was found that crack growth rate as a function of stress intensity was characterized by an apparent threshold for crack growth, a stage where the growth rate increased sharply, and a stage where the growth rate was unchanged over a significant range of stress intensity. Cracking proceeded on load application with little or no detectable incubation period. Gaseous hydrogen embrittlement susceptibility increased with increasing yield strength.

  19. Dynamic recrystallization behavior and kinetics of high strength steel

    Institute of Scientific and Technical Information of China (English)

    吴光亮; 周超洋; 刘新彬

    2016-01-01

    The dynamic recrystallization behavior of high strength steel during hot deformation was investigated. The hot compression test was conducted in the temperature range of 950−1150 °C under strain rates of 0.1, 1 and 5 s−1. It is observed that dynamic recrystallization (DRX) is the main flow softening mechanism and the flow stress increases with decreasing temperature and increasing strain rate. The relationship between material constants (Q, n, α and lnA) and strain is identified by the sixth order polynomial fit. The constitutive model is developed to predict the flow stress of the material incorporating the strain softening effect and verified. Moreover, the critical characteristics of DRX are extracted from the stress−strain curves under different deformation conditions by linear regression. The dynamic recrystallization volume fraction decreases with increasing strain rate at a constant temperature or decreasing deformation temperature under a constant strain rate. The kinetics of DRX increases with increasing deformation temperature or strain rate.

  20. The influence of clay additives in Portland cement on the compressive strength of the cement stone

    Directory of Open Access Journals (Sweden)

    A.R. Gaifullin

    2015-11-01

    Full Text Available The introduction of mineral additives to binders, especially to Portland cement, is one of the promising trends for solving the resource and energy saving problems, as well as problems of environmental protection during production and application. Expanding the supplementary cementitious materials resource base can be achieved through the use of natural pozzolans and thermally activated polymineral clays(commonly known as glinites in Russia. One type of glinite is metakaolin, which is obtained by calcination of kaolin clays. Metakaolin is widely and effectively used as a pozzolanic additive due to its beneficial effect on the physical and mechanical properties of Portland cement-based materials. The obstacle to its wide production and use are the limited deposits of pure kaolin clays in many countries, including the Russian Federation. In this respect, the studies of pozzolanic activity of the most common mineral clays and their use in some countries have significantly advanced. Similar studies were widely performed in the 1940s in USSR. It seems reasonable to renew this trend to provide a scientific base for the production of local pozzolans made of clays commonly used in different regions. Comparative studies of the effect of 5 clays differing in mineral and chemical composition, calcination temperature and specific surface area, and high-quality metakaolin, on the strength of hardened Portland cement paste have been performed. It has been established that introducing 5…10 % of composite clays calcined at 400…8000 C° and milled to a specific surface area of 290…800 m2/kg into Portland cement enhanced the strength of the hardened cement paste considerably better than the introduction of metakaolin with a specific surface area of 1200 m2/kg. The findings of the study suggest that many kinds of commonly used polymineral clays have a specific calcination temperature and dispersity, which results in a higher pozzolanic activity compared with

  1. Feature preserving compression of high resolution SAR images

    Science.gov (United States)

    Yang, Zhigao; Hu, Fuxiang; Sun, Tao; Qin, Qianqing

    2006-10-01

    Compression techniques are required to transmit the large amounts of high-resolution synthetic aperture radar (SAR) image data over the available channels. Common Image compression methods may lose detail and weak information in original images, especially at smoothness areas and edges with low contrast. This is known as "smoothing effect". It becomes difficult to extract and recognize some useful image features such as points and lines. We propose a new SAR image compression algorithm that can reduce the "smoothing effect" based on adaptive wavelet packet transform and feature-preserving rate allocation. For the reason that images should be modeled as non-stationary information resources, a SAR image is partitioned to overlapped blocks. Each overlapped block is then transformed by adaptive wavelet packet according to statistical features of different blocks. In quantifying and entropy coding of wavelet coefficients, we integrate feature-preserving technique. Experiments show that quality of our algorithm up to 16:1 compression ratio is improved significantly, and more weak information is reserved.

  2. A high-dynamic range transimpedance amplifier with compression

    Science.gov (United States)

    Mičušík, D.; Zimmermann, H.

    2007-02-01

    This paper presents a transimpedance amplifier (TIA) with the logarithmic compression of the input current signal. The presented TIA has two regions of operation: a linear one for small input current signals and a compression one for high input currents, that could otherwise saturate the TIA. The measured -3dB bandwidth in the linear region of operation is 102MHz. The measured maximum input current overdrive is 20.5mA. However, the maximum of the monotonic compression is approx. 8mA. Using the compression technique we could achieve low rms equivalent input noise current (~20.2nA) within the measured bandwidth and with approx. 2pF capacitance at the input. Thus the dynamic range at the input of the TIA is approx. 120dB considering the maximal current overdrive. The proposed TIA represents the input stage of a optical receiver with integrated differential 50Ω output driver. The optical receiver occupies approx. 1.24mm2 in 0.35 μm SiGe BiCMOS technology and consumes 78mA from 5V supply.

  3. Development of a high strength high toughness ausferritic steel

    Energy Technology Data Exchange (ETDEWEB)

    Putatunda, Susil K., E-mail: sputa@eng.wayne.edu [Department of Chemical Engineering and Material Science, Wayne State University, 5050 Anthony Wayne Dr., Detroit, MI 48202 (United States); Singar, Arjun V. [Department of Chemical Engineering and Material Science, Wayne State University, 5050 Anthony Wayne Dr., Detroit, MI 48202 (United States); Tackett, Ronald; Lawes, Gavin [Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201 (United States)

    2009-07-15

    A new ausferritic steel with high strength and exceptionally high fracture toughness has been developed. This steel has been synthesized integrating concepts from Austempered Ductile Cast Iron (ADI) technology. The influence of the austempering temperature on the microstructure and mechanical properties of this steel at room temperature and ambient atmosphere has been examined. The effect of microstructure on the plane strain fracture toughness and on the magnetic, electrical, and thermal properties was also investigated. Compact tension and cylindrical tensile specimens prepared from the low alloy medium carbon steel with high silicon content were initially austenitized at 927 deg. C for 2 h and then subsequently austempered at several temperatures between 260 deg. C (500 F) and 400 deg. C (750 F) to produce different microstructures. The microstructures were characterized by X-ray diffraction, scanning electron microscopy and optical metallography. A combination of exceptionally high yield strength (1336 MPa) and a high fracture of toughness of 116 MPa{radical}m (a value comparable to maraging steel) was obtained in this steel after austempering at 316 deg. C (600 F) for 2 h. Potential applications of this steel include the inexpensive fabrication of armored plates and components requiring high reliability and durability.

  4. Offshore compression system design for low cost high and reliability

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Carlos J. Rocha de O.; Carrijo Neto, Antonio Dias; Cordeiro, Alexandre Franca [Chemtech Engineering Services and Software Ltd., Rio de Janeiro, RJ (Brazil). Special Projects Div.], Emails: antonio.carrijo@chemtech.com.br, carlos.rocha@chemtech.com.br, alexandre.cordeiro@chemtech.com.br

    2010-07-01

    In the offshore oil fields, the oil streams coming from the wells usually have significant amounts of gas. This gas is separated at low pressure and has to be compressed to the export pipeline pressure, usually at high pressure to reduce the needed diameter of the pipelines. In the past, this gases where flared, but nowadays there are a increasing pressure for the energy efficiency improvement of the oil rigs and the use of this gaseous fraction. The most expensive equipment of this kind of plant are the compression and power generation systems, being the second a strong function of the first, because the most power consuming equipment are the compressors. For this reason, the optimization of the compression system in terms of efficiency and cost are determinant to the plant profit. The availability of the plants also have a strong influence in the plant profit, specially in gas fields where the products have a relatively low aggregated value, compared to oil. Due this, the third design variable of the compression system becomes the reliability. As high the reliability, larger will be the plant production. The main ways to improve the reliability of compression system are the use of multiple compression trains in parallel, in a 2x50% or 3x50% configuration, with one in stand-by. Such configurations are possible and have some advantages and disadvantages, but the main side effect is the increase of the cost. This is the offshore common practice, but that does not always significantly improve the plant availability, depending of the previous process system. A series arrangement and a critical evaluation of the overall system in some cases can provide a cheaper system with equal or better performance. This paper shows a case study of the procedure to evaluate a compression system design to improve the reliability but without extreme cost increase, balancing the number of equipment, the series or parallel arrangement, and the driver selection. Two cases studies will be

  5. Micro-computed tomography assisted distal femur metaphyseal blunt punch compression for determining trabecular bone strength in mice.

    Science.gov (United States)

    Sankar, Uma; Pritchard, Zachary J; Voor, Michael J

    2016-05-03

    Shorter generation time and the power of genetic manipulation make mice an ideal model system to study bone biology as well as bone diseases. However their small size presents a challenge to perform strength measurements, particularly of the weight-bearing cancellous bone in the murine long bones. We recently developed an improved method to measure the axial compressive strength of the cancellous bone in the distal femur metaphysis in mice. Transverse micro-computed tomography image slices that are 7µm thick were used to locate the position where the epiphysis-metaphysis transition occurs. This enabled the removal of the distal femur epiphysis at the exact transition point exposing the full extent of metaphyseal trabecular bone, allowing more accurate and consistent measurement of its strength. When applied to a murine model system consisting of five month old male wild-type (WT) and Ca(2+)/calmodulin dependent protein kinase kinase 2 (CaMKK2) knockout (KO) Camkk2(-/-) mice that possess recorded differences in trabecular bone volume, data collected using this method showed good correlation between bone volume fraction and strength of trabecular bone. In combination with micro-computed tomography and histology, this method will provide a comprehensive and consistent assessment of the microarchitecture and tissue strength of the cancellous bone in murine mouse models.

  6. THEORETICAL ASPECTS, EXPERIMENTAL INVESTIGATIONS AND EFFICIENCY IN USAGE OF HIGH-STRENGTH CONCRETE FOR BRIDGE STRUCTURES

    Directory of Open Access Journals (Sweden)

    G. D. Liakhevich

    2014-01-01

    Full Text Available In Belarus concrete with strength up to 60 MPA is used for construction. At the same time high strength concrete with compressive strength above 60 MPA is widely used in all industrially developed countries. High- strength concrete is included in regulatory documents of the European Union and that fact has laid a solid foundation for its application. High strength concrete is produced using highly dispersed silica additives, such as micro-silica and plasticizers (super-plasticizers with a water/cement (w/c ratio not greater than 0.4.Theoretical aspects of high-strength concrete for bridge structures have been studied in the paper. The paper shows a positive impact of highly dispersed additives on structure and physico-mechanical properties of cement compositions, namely: reduction of total porosity of a cement stone in concrete while increasing volumetric concentration and dispersion of a filler; binding of calcium hydroxide with the help of amorphised micro-silica; increased activity of mineral additives during their thin shredding; acceleration of the initial stage of chemical hardening of cement compositions with highly dispersed particle additives that serve as centers of crystallization; “binder-additive” cluster formation due to high surface energy of highly dispersed additive particles; hardening of surface area between a cement stone and aggregates in concrete; high-strength concretes are gaining strength much faster than conventional concretes.Technology of preparation and composition of high-strength concrete using highly dispersed mineral additives and super-plasticizer has been developed in the paper. This concrete will ensure a higher density, wa- ter-and gas tightness, increased resistance to aggressive environment, reduced consumption of concrete and reinforcement, reduced transport and installation weight, increased initial strength, early easing of shutters and preliminary compression, increased length of bridge spans

  7. Effect of water absorption by the aggregate on properties of high-strength lightweight concrete

    Energy Technology Data Exchange (ETDEWEB)

    Punkki, J.

    1995-12-31

    Recently, high-strength lightweight concrete has become an interesting building material for the offshore oil industry. This doctoral thesis presents an experimental investigation of the effect of water absorption by three different types of lightweight aggregates. One type did not show any water absorption ability at all and so represented no problem to the concrete production. For the two other high-strength aggregates, which were of more conventional types, the water absorption depended not only on the properties of the aggregates, but also on the concrete mixing procedure and the properties of the fresh cement paste. When water absorbing lightweight aggregate was used in a dry condition, the workability of the concrete was significantly reduced by the water absorption of the aggregate. This effect was not present when prewetted aggregate was used. The water absorption by the lightweight aggregate also affected the early compressive strength of concrete. After one day, dry aggregate gave on the average 10 MPa higher compressive strength than did prewetted aggregate. The strength-density ratio was affected by the moisture condition of the aggregate. Dry lightweight aggregate gave 9 MPa higher compressive strength at a density of 2000 kg/m{sup 3} compared to that of prewetted aggregate. The water absorption by the lightweight also affected the microstructure of the hardened concrete. Dry lightweight aggregate gave a slightly better microstructure than normal weight aggregate. The results indicate that the use of prewetted aggregate adversely affected the transition zone between the aggregate and the cement paste. 69 refs., 58 figs., 42 tabs.

  8. Evaluation of Compressive Strength and Stiffness of Grouted Soils by Using Elastic Waves

    Directory of Open Access Journals (Sweden)

    In-Mo Lee

    2014-01-01

    Full Text Available Cement grouted soils, which consist of particulate soil media and cementation agents, have been widely used for the improvement of the strength and stiffness of weak ground and for the prevention of the leakage of ground water. The strength, elastic modulus, and Poisson’s ratio of grouted soils have been determined by classical destructive methods. However, the performance of grouted soils depends on several parameters such as the distribution of particle size of the particulate soil media, grouting pressure, curing time, curing method, and ground water flow. In this study, elastic wave velocities are used to estimate the strength and elastic modulus, which are generally obtained by classical strength tests. Nondestructive tests by using elastic waves at small strain are conducted before and during classical strength tests at large strain. The test results are compared to identify correlations between the elastic wave velocity measured at small strain and strength and stiffness measured at large strain. The test results show that the strength and stiffness have exponential relationship with elastic wave velocities. This study demonstrates that nondestructive methods by using elastic waves may significantly improve the strength and stiffness evaluation processes of grouted soils.

  9. Experimental Analysis of Concrete Strength at High Temperatures and after Cooling

    Directory of Open Access Journals (Sweden)

    E. Klingsch

    2009-01-01

    Full Text Available In recent years, the cement industry has been criticized for emitting large amounts of carbon dioxide; hence it is developing environment-friendly cement, e.g., blended, supersulfated slag cement (SSC. This paper presents an experimental analysis of the compressive strength development of concrete made from blended cement in comparison to ordinary cement at high temperature. Three different types of cement were used during these tests, an ordinary portland cement (CEM I, a portland limestone cement (CEM II-A-LL and a new, supersulfated slag cement (SSC. The compressive strength development for a full thermal cycle, including cooling down phase, was investigated on concrete cylinders. It is shown that the SSC concrete specimens perform similar to ordinary cement specimens. 

  10. Strength criterion for rocks under compressive-tensile stresses and its application

    Directory of Open Access Journals (Sweden)

    Mingqing You

    2015-08-01

    Full Text Available Estimating in-situ stress with hydraulic borehole fracturing involves tensile strength of rock. Several strength criteria with three parameters result in tensile strengths with great differences, although they may describe the relation between strength of rock and confining pressure with low misfits. The exponential criterion provides acceptable magnitudes of tensile strengths for granites and over-estimates that for other rocks, but the criterion with tension cut-off is applicable to all rocks. The breakdown pressure will be lower than the shut-in pressure during hydraulic borehole fracturing, when the maximum horizontal principal stress is 2 times larger than the minor one; and it is not the peak value in the first cycle, but the point where the slope of pressure-time curve begins to decline.

  11. Bilateral high radial nerve compressions: a case report.

    Science.gov (United States)

    Chuangsuwanich, A; Muangsombut, S; Sangruchi, T

    2000-06-01

    A 40-year-old woman with bilateral high radial nerve compressions by non-traumatic cause was reported. It occurred first at the right radial nerve which was explored after a period of investigation and conservative treatment. Two constricted sites 2.0 cm apart of the right radial nerve crossed by branches of the radial collateral artery beneath the lateral head of the triceps were found. The constricted sites including tissue in between was resected and replaced with a sural nerve graft. One year later the patient had the same episode on the left side. The operative finding was the same as the previous one. Sural nerve graft was performed after neurolysis had failed. The patient's normal radial nerve function returned in one year. This is the first reported case in the literature of bilateral high radial nerve compressions by branches of the radial collateral artery.

  12. The Turbulent Dynamo in Highly Compressible Supersonic Plasmas

    CERN Document Server

    Federrath, Christoph; Bovino, Stefano; Schleicher, Dominik R G

    2014-01-01

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly-compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early Universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024^3 cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = nu/eta = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm >= 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm_crit = 129 (+43, -31), showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present a...

  13. New experimental capabilities and theoretical insights of high pressure compression waves

    Energy Technology Data Exchange (ETDEWEB)

    Orlikowski, D; Nguyen, J; Patterson, J R; Minich, R; Martin, L P; Holmes, N

    2007-07-20

    Currently there are three platforms that offer quasi-isentropic compression or ramp-wave compression (RWC): light-gas gun, magnetic flux (Z-pinch), and laser. We focus here on the light-gas gun technique and on some current theoretical insights from experimental data. A gradient impedance through the length of the impactor provides the pressure pulse upon impactor to the subject material. Applications and results are given concerning high-pressure strength and liquid to solid, phase transition of water plus its associated phase fraction history. We also introduce the Korteweg-deVries-Burgers equation as a means to understand the evolution these RWC waves that propagate through the thickness of the subject material. This equation has the necessary competition between non-linear, dispersion, and dissipation processes, which is shown through observed structures that are manifested in the experimental particle velocity histories. Such methodology points towards a possible quantifiable dissipation, through which RWC experiments may be analyzed.

  14. Mechanical behavior of high strength ceramic fibers at high temperatures

    Science.gov (United States)

    Tressler, R. E.; Pysher, D. J.

    1991-01-01

    The mechanical behavior of commercially available and developmental ceramic fibers, both oxide and nonoxide, has been experimentally studied at expected use temperatures. In addition, these properties have been compared to results from the literature. Tensile strengths were measured for three SiC-based and three oxide ceramic fibers for temperatures from 25 C to 1400 C. The SiC-based fibers were stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures. Extensive creep and creep-rupture experiments have been performed on those fibers from this group which had the best strengths above 1200 C in both single filament tests and tests of fiber bundles. The creep rates for the oxides are on the order of two orders of magnitude faster than the polymer derived nonoxide fibers. The most creep resistant filaments available are single crystal c-axis sapphire filaments. Large diameter CVD fabricated SiC fibers are the most creep and rupture resistant nonoxide polycrystalline fibers tested to date.

  15. Overall buckling behavior of Q460 high strength steel welded box section columns under axial compression%Q460高强钢焊接箱形截面轴压构件整体稳定性能研究

    Institute of Scientific and Technical Information of China (English)

    班慧勇; 施刚; 石永久; 王元清

    2013-01-01

    为研究高强度钢材轴心受压钢柱的整体稳定性能,对5个国产Q460钢材焊接箱形截面柱进行了轴心受压试验研究.试验对试件的几何初弯曲、荷载初偏心以及截面的纵向残余应力分布均进行了测量.基于试验结果,分析了该类钢柱的失稳破坏形态和整体稳定承载力,建立了有限元分析模型并对试验结果进行模拟计算.研究结果表明:试件破坏模态均为整体弯曲失稳形态,大部分试件稳定承载力高于规范设计值;有限元分析模型能够准确地考虑几何初始缺陷和残余应力的影响,计算结果与试验结果吻合良好;通过与国内外钢结构设计规范的对比,提出了国产Q460高强钢焊接箱形截面轴压构件整体稳定设计的建议方法,即可以统一采用我国或欧洲规范的b类曲线进行设计,而不需要按板件宽厚比大小进行分类.%In order to investigate the overall buckling behavior of Q460 high strength steel columns under axial compression, 5 full-scale specimens were tested and the initial bending, loading eccentricity and sectional residual stress were also measured. Based on the experimental results, the failure mode and buckling capacity were clarified, and a finite element model was established to simulate the overall buckling behavior of such columns. It is found that the finite element model can well describe the effects caused by both initial geometric imperfections and residual stresses, and the calculated results through finite element analysis have a good agreement with experimental results. The validated model was further implemented for a large number of parametric analysis, and the calculated results were compared with different steel structure design codes. The design method for the overall buckling behavior of Q460 high strength steel welded box section columns was suggested, i. e. the column curve b in both GB 50017-2003 and Eurocode 3 can be employed to design such structural

  16. High-Frequency Chest Compression: A Summary of the Literature

    OpenAIRE

    Dosman, Cara F; Jones, Richard L

    2005-01-01

    The purpose of the present literature summary is to describe high-frequency chest compression (HFCC), summarize its history and outline study results on its effect on mucolysis, mucus transport, pulmonary function and quality of life. HFCC is a mechanical method of self-administered chest physiotherapy, which induces rapid air movement in and out of the lungs. This mean oscillated volume is an effective method of mucolysis and mucus clearance. HFCC can increase independence. Some studies have...

  17. IMPACT OF TONE MAPPING IN HIGH DYNAMIC RANGE IMAGE COMPRESSION

    OpenAIRE

    Narwaria, Manish; Perreira Da Silva, Matthieu; Le Callet, Patrick; Pépion, Romuald

    2014-01-01

    International audience; Tone mapping or range reduction is often used in High Dynamic Range (HDR) visual signal compression to take advantage of the existing image/video coding architectures. Thus, it is important to study the impact of tone mapping on the visual quality of decompressed HDR visual signals. To our knowledge, most of the existing studies focus only on the quality loss in the resultant low dynamic range (LDR) signal (obtained via tone mapping) and typically employ LDR displays f...

  18. THE INFLUENCE OF SATURATION ON THE UNIAXIAL COMPRESSIVE STRENGTH OF LIMESTONE IN EXPLORATION AREA CRNOGLAV NEAR NEUM

    Directory of Open Access Journals (Sweden)

    Zlatko Briševac

    2014-12-01

    Full Text Available Exploration area Crnoglav, near Neum, Bosnia and Herzegovina, is composed of limestone sedimentary rock. Research of influence of saturation with water was made on intact material from this area on physical and mechanical properties of the rock: uniaxial compressive strength, module of deformation, point load strength index and Schmidt rebound hardness. Tests were conducted on recommendation of International Society for Rock Mechanics (ISRM Suggested methods and Croatian Standards. Results showed different influence of saturation on values of respective test. Ratios that help with calculations of physical and mechanical properties of rock in their saturated state based on their known values in dry state are presented in this paper (the paper is published in Croatian.

  19. Measurement of In-Plane Shear Strength of Carbon/Carbon Composites by Compression of Double-Notched Specimens

    Science.gov (United States)

    Yan, K. F.; Zhang, C. Y.; Qiao, S. R.; Song, C. Z.; Han, D.; Li, M.

    2012-01-01

    The compression of a double-notched specimen was used to determine the in-plane shear strength (IPSS) of a carbon/carbon composite in the paper. The effects of the notch distance ( L), thickness ( T), and notch width ( W) and supporting jig on the IPSS of the double-notched specimens were investigated numerically and experimentally. The fracture surfaces were examined by a scanning electron microscope. It was found that the IPSS varied with L. Thin specimen yielded low strength. W has little effect on IPSS. The main failure modes include the matrix shear cracking, delamination, fracture and pullout of fibers or fiber bundles. Meanwhile, a supporting jig can provide lateral support and prevent buckling, therefore lead to the failure in a shear mode.

  20. Behavior of High Water-cement Ratio Concrete under Biaxial Compression after Freeze-thaw Cycles

    Institute of Scientific and Technical Information of China (English)

    SHANG Huaishuai; SONG Yupu; OU Jinping

    2008-01-01

    The high water-cement ratio concrete specimens under biaxial compression that completed in a triaxial testing machine were experimentally studied.Strength and deformations of plain concrete specimens after 0,25,50 cycles of freeze-thaw.Influences of freeze-thaw cycles and stress ratio on the peak stress and deformation of this point were analyzed aecording to the experimental results.Based on the test data,the failure criterion expressed in terms of principal stress after difierent cycles of freeze-thaw,and the failure criterion with consideration of the influence of freeze-thaw cycle and sffess ratio were proposed respectively.

  1. Friction Stir Spot Welding of Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri; Grant, Glenn J.; Santella, M. L.

    2009-11-13

    Friction stir spot welding techniques were developed to successfully join several advanced high strength steels. Two distinct tool materials were evaluated to determine the effect of tool materials on the process parameters and joint properties. Welds were characterized primarily via lap shear, microhardness, and optical microscopy. Friction stir spot welds were compared to the resistance spot welds in similar strength alloys by using the AWS standard for resistance spot welding high strength steels. As further comparison, a primitive cost comparison between the two joining processes was developed, which included an evaluation of the future cost prospects of friction stir spot welding in advanced high strength steels.

  2. Mechanical strength and thermophysical properties of PM212: A high temperature self-lubricating powder metallurgy composite

    Science.gov (United States)

    Edwards, Phillip M.; Sliney, Harold E.; Dellacorte, Christopher; Whittenberger, J. Daniel; Martineau, Robert R.

    1990-01-01

    A powder metallurgy composite, PM212, composed of metal bonded chromium carbide and solid lubricants is shown to be self-lubricating to a maximum application temperature of 900 C. The high temperature compressive strength, tensile strength, thermal expansion and thermal conductivity data needed to design PM212 sliding contact bearings and seals are reported for sintered and isostatically pressed (HIPed) versions of PM212. Other properties presented are room temperature density, hardness, and elastic modulus. In general, both versions appear to have adequate strength to be considered as sliding contact bearing materials, but the HIPed version, which is fully dense, is much stronger than the sintered version which contains about 20 percent pore volume. The sintered material is less costly to make, but the HIPed version is better where high compressive strength is important.

  3. STUDY OF EXPERIMENTAL SAMPLES WITH DIFFERENT CONFIGURATIONS AT THE JOINTS COMPRESSIVE STRENGTH

    Directory of Open Access Journals (Sweden)

    E. N. Magomedova

    2013-01-01

    Full Text Available The article marked the behavior of concrete under the action of water, the effect of moisture and water saturation on the performance and durability of concrete waterproofing; offered special configuration interface, allowing to increase the strength characteristics of the concrete structure, the results of experimental studies; conclusions about the relationship configuration of joints and their strength.

  4. Evaluation of compressive strength in cement mortars, according to the dosage established by the colombian seismic resistance code. Case study

    Directory of Open Access Journals (Sweden)

    Sergio Giovanny Valbuena Porras

    2016-06-01

    Full Text Available Context: In a masonry wall the mortar it is between 10 and 20% of the total volume of the system, despite its effect on the behavior of it is significantly higher than this percentage indicates.Objective: The purpose of this research was to evaluate the resistance to compression of two types of mortar paste (A and B, prepared with natural sand from the town of Usme in Bogotá, in accordance with the proportions set by the Standard Colombian earthquake Resistant regulation (NSR-10.Method: Two types of mortar paste were prepared, according to the proportions of cement and sand established in NSR-10 section D.3.4-1 of (Table 1; these proportions were calculated using a 0.0028 m3 container for measuring unit weight. For type A mortar rock sand was used and river sand for type B mortar.Results: The resistance to compression for mortars type A at the end of the study was on average 84% of the expected resistance, whereas for type B mortars it averaged 64% above the expected resistance.Conclusion: Mortar mixes made with crushed or rock (type A arena do not reach the compressive strength required demanded by regulatory standards, despite complying with the dosage established in NSR 10 and with NTC quality criteria; while the natural sand origin or natural river sand meet these standards.

  5. An experimental investigation into the damage resistance and compression-after-impact strength of T800H/3900-2

    Science.gov (United States)

    Vietinghoff, H.; Poon, C.; Straznicky, P. V.; Gould, R.

    1993-01-01

    An experimental investigation was conducted into impact behavior of a Toray T800H/3900-2 material system, a system representative of the most recent generation of toughened graphite-epoxy composites selected for use in several new airframes. In the investigation, test specimens featuring quasi-isotropic and midplane symmetric layup with 24 plies were fabricated and impacted at five different impact energy levels, resulting in damage ranging from barely visible to severe. Damage was characterized using nondestructive and destructive inspection, including ultrasound and x-ray techniques, and the specimens were then compressively loaded to failure. The carefully controlled set of experiments resulted in a detailed three dimensional characterization of the damage induced in the selected laminate layup for a range of impact energies. Compression after impact testing resulted in a correlation of impact energy and damage area with residual compressive strength. The results will be used to calibrate and test the analytical prediction methods being developed as part of a project on impact resistance and tolerance of composite materials, and as reference data on the material system.

  6. Equation of State for Shock Compression of High Distension Solids

    Science.gov (United States)

    Grady, Dennis

    2013-06-01

    Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additivity of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence supports acceleration of shock-induced phase transformation on the Hugoniot with increasing levels of initial distention for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed facet of the shock compression are introduced into the EOS model.

  7. Viscosity and compressibility of diacylglycerol under high pressure

    Science.gov (United States)

    Malanowski, Aleksander; Rostocki, A. J.; Kiełczyński, P.; Szalewski, M.; Balcerzak, A.; Kościesza, R.; Tarakowski, R.; Ptasznik, S.; Siegoczyński, R. M.

    2013-03-01

    The influence of high pressure on viscosity and compressibility of diacylglycerol (DAG) oil has been presented in this paper. The investigated DAG oil was composed of 82% of DAGs and 18% TAGs (triacylglycerols). The dynamic viscosity of DAG was investigated as a function of the pressure up to 400 MPa. The viscosity was measured by means of the surface acoustic wave method, where the acoustic waveguides were used as sensing elements. As the pressure was rising, the larger ultrasonic wave attenuation was observed, whereas amplitude decreased with the liquid viscosity augmentation. Measured changes of physical properties were most significant in the pressure range near the phase transition. Deeper understanding of DAG viscosity and compressibility changes versus pressure could shed more light on thermodynamic properties of edible oils.

  8. A high-power SLED 2 pulse compression system

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, N.M. [California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics; Farkas, Z.D.; Lavine, T.L.; Menegat, A.; Ruth, R.D.; Wilson, P.B. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Nantista, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics

    1992-03-01

    The enhancement of peak power by means of RF pulse compression has found important application for driving high energy electron linacs, the SLAC linac in particular. The SLAC Energy Doubler (SLED), however, yields a pulse shape in the form of a decaying exponential which limits the applicability of the method. Two methods of improving this situation have been suggested: binary pulse compression (BPC), in which the pulse is compressed by successive factors of two, and SLED II in which the pair of resonant cavities of SLED are replaced by long resonant delay lines (typically waveguides). Intermediate schemes in which the cavity pair is replaced by sequences of coupled cavities have also been considered. In this paper we describe our efforts towards the design and construction of high-power SLED II systems, which are intended to provide drivers for various advanced accelerator test facilities and potentially for the Next Linear Collider itself. The design path we have chosen requires the development of a number of microwave components in overmoded waveguide, and the bulk of this paper will be devoted to reporting our progress.

  9. Compression of structured high-throughput sequencing data.

    Directory of Open Access Journals (Sweden)

    Fabien Campagne

    Full Text Available Large biological datasets are being produced at a rapid pace and create substantial storage challenges, particularly in the domain of high-throughput sequencing (HTS. Most approaches currently used to store HTS data are either unable to quickly adapt to the requirements of new sequencing or analysis methods (because they do not support schema evolution, or fail to provide state of the art compression of the datasets. We have devised new approaches to store HTS data that support seamless data schema evolution and compress datasets substantially better than existing approaches. Building on these new approaches, we discuss and demonstrate how a multi-tier data organization can dramatically reduce the storage, computational and network burden of collecting, analyzing, and archiving large sequencing datasets. For instance, we show that spliced RNA-Seq alignments can be stored in less than 4% the size of a BAM file with perfect data fidelity. Compared to the previous compression state of the art, these methods reduce dataset size more than 40% when storing exome, gene expression or DNA methylation datasets. The approaches have been integrated in a comprehensive suite of software tools (http://goby.campagnelab.org that support common analyses for a range of high-throughput sequencing assays.

  10. High-resolution three-dimensional imaging with compress sensing

    Science.gov (United States)

    Wang, Jingyi; Ke, Jun

    2016-10-01

    LIDAR three-dimensional imaging technology have been used in many fields, such as military detection. However, LIDAR require extremely fast data acquisition speed. This makes the manufacture of detector array for LIDAR system is very difficult. To solve this problem, we consider using compress sensing which can greatly decrease the data acquisition and relax the requirement of a detection device. To use the compressive sensing idea, a spatial light modulator will be used to modulate the pulsed light source. Then a photodetector is used to receive the reflected light. A convex optimization problem is solved to reconstruct the 2D depth map of the object. To improve the resolution in transversal direction, we use multiframe image restoration technology. For each 2D piecewise-planar scene, we move the SLM half-pixel each time. Then the position where the modulated light illuminates will changed accordingly. We repeat moving the SLM to four different directions. Then we can get four low-resolution depth maps with different details of the same plane scene. If we use all of the measurements obtained by the subpixel movements, we can reconstruct a high-resolution depth map of the sense. A linear minimum-mean-square error algorithm is used for the reconstruction. By combining compress sensing and multiframe image restoration technology, we reduce the burden on data analyze and improve the efficiency of detection. More importantly, we obtain high-resolution depth maps of a 3D scene.

  11. Compressed gas domestic aerosol valve design using high viscous product

    Directory of Open Access Journals (Sweden)

    A Nourian

    2016-10-01

    Full Text Available Most of the current universal consumer aerosol products using high viscous product such as cooking oil, antiperspirants, hair removal cream are primarily used LPG (Liquefied Petroleum Gas propellant which is unfriendly environmental. The advantages of the new innovative technology described in this paper are: i. No butane or other liquefied hydrocarbon gas is used as a propellant and it replaced with Compressed air, nitrogen or other safe gas propellant. ii. Customer acceptable spray quality and consistency during can lifetime iii. Conventional cans and filling technology There is only a feasible energy source which is inert gas (i.e. compressed air to replace VOCs (Volatile Organic Compounds and greenhouse gases, which must be avoided, to improve atomisation by generating gas bubbles and turbulence inside the atomiser insert and the actuator. This research concentrates on using "bubbly flow" in the valve stem, with injection of compressed gas into the passing flow, thus also generating turbulence. The new valve designed in this investigation using inert gases has advantageous over conventional valve with butane propellant using high viscous product (> 400 Cp because, when the valving arrangement is fully open, there are negligible energy losses as fluid passes through the valve from the interior of the container to the actuator insert. The use of valving arrangement thus permits all pressure drops to be controlled, resulting in improved control of atomising efficiency and flow rate, whereas in conventional valves a significant pressure drops occurs through the valve which has a complex effect on the corresponding spray.

  12. Determination of Relationship between Dielectric Properties, Compressive Strength, and Age of Concrete with Rice Husk Ash Using Planar Coaxial Probe

    Directory of Open Access Journals (Sweden)

    Piladaeng Nawarat

    2016-02-01

    Full Text Available This paper deals with an investigation of the dielectric properties of concretes that includes rice husk ash using a planar coaxial probe. The planar coaxial probe has a planar structure with a microstrip and coaxial features. The measurement was performed over the frequency range of 0.5-3.5 GHz, and concrete specimens with different percentages of rice husk ash were tested. The results indicated that the dielectric constant of the concretes was inversely proportional to the frequency, while the conductivity was proportional to the frequency. The dielectric constant decreased with the increasing age of the concrete at the frequency of 1 GHz. The conductivity of the concrete decreased with the increasing age of the concrete at the frequency of 3.2 GHz. In addition, the dielectric constant and the conductivity decreased when the compressive strength increased. It was also shown that the obtained dielectric properties of the concrete could be used to investigate the relationship between the compressive strength and age of the concrete. Moreover, there is an opportunity to apply the proposed probe to determine the dielectric properties of other materials.

  13. Evaluation of compressive strength and water absorption of soil-cement bricks manufactured with addition of pet (polyethylene terephthalate wastes

    Directory of Open Access Journals (Sweden)

    João Alexandre Paschoalin Filho

    2016-04-01

    Full Text Available This paper presents the evaluation of compressive strength of soil-cement bricks obtained by the inclusion in their mixture of PET flakes through mineral water bottles grinding. The Polyethylene Terephthalate (PET has been characterized by its difficulty of disaggregation in nature, requiring a long period for this. On the other hand, with the increase in civil construction activities the demand for raw material also increases, causing considerable environmental impacts. In this context, the objective of this research is to propose a simple methodology, preventing its dumping and accumulation in irregular areas, and reducing the demand of raw materials by the civil construction industry. The results showed that compressive strengths obtained were lower than recommended by NBR 8491 (Associação Brasileira de Normas Técnicas [ABNT], 2012b at seven days of curing time. However, they may be used as an alternative solution in masonry works in order to not submit themselves to great loads or structural functions. The studied bricks also presented water absorption near to recommended values by NBR 8491 (ABNT, 2012b. Manufacturing costs were also determined for this brick, comparing it with the costs of other brick types. Each brick withdrew from circulation approximately 300 g of PET waste. Thus, for an area of 1 m2 the studied bricks can promote the withdrawal of approximately 180 beverage bottles of 2 L capacity.

  14. Compressive Strength, Pore Size Distribution and Chloride-ion Penetration of Recycled Aggregate Concrete Incorporating Class-F Fly Ash

    Institute of Scientific and Technical Information of China (English)

    KOU Shicong; C S Poon

    2006-01-01

    The effects of fly ash on the compressive strength, pore size distribution ard chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mixtures were prepared. The concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/m3 , respectively. The concrete mixtures in series Ⅱ had a water-to-binder ratio and a cement content of 0.45 and 400 kg/m3 respectively. Recycled aggregate was used as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In addition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. The results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. The total porosity and average porosity diameter of the concrete increased as the recycled aggregate content increased. Furthermore, an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ash improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.

  15. Radius bone strength in bending, compression, and falling and its correlation with clinical densitometry at multiple sites.

    Science.gov (United States)

    Lochmüller, Eva-Maria; Lill, Christoph A; Kuhn, Volker; Schneider, Erich; Eckstein, Felix

    2002-09-01

    This study comprehensively analyzes the ability of site-specific and nonsite-specific clinical densitometric techniques for predicting mechanical strength of the distal radius in different loading configurations. DXA of the distal forearm, spine, femur, and total body and peripheral quantitative computed tomography (pQCT) measurements of the distal radius (4, 20, and 33%) were obtained in situ (with soft tissues) in 129 cadavers, aged 80.16 +/- 9.8 years. Spinal QCT and calcaneal quantitative ultrasound (QUS) were performed ex situ in degassed specimens. The left radius was tested in three-point bending and axial compression, and the right forearm was tested in a fall configuration, respectively. Correlation coefficients with radius DXA were r = 0.89, 0.84, and 0.70 for failure in three-point bending, axial compression, and the fall simulation, respectively. The correlation with pQCT (r = 0.75 for multiple regression models with the fall) was not significantly higher than for DXA. Nonsite-specific measurements and calcaneal QUS displayed significantly (p radius, nonsite-specific measurements are less accurate for this purpose, and QUS adds only little independent information to site-specific bone mass. Therefore, the noninvasive diagnosis of loss of strength at the distal radius should rely on site-specific measurements with DXA or pQCT and may be the earliest chance to detect individuals at risk of osteoporotic fracture.

  16. Strength Anisotropy of Berea Sandstone: Results of X-Ray Computed Tomography, Compression Tests, and Discrete Modeling

    Science.gov (United States)

    Kim, Kwang Yeom; Zhuang, Li; Yang, Hwayoung; Kim, Hanna; Min, Ki-Bok

    2016-04-01

    Berea sandstone in northern Ohio is a transversely isotropic rock. X-ray CT investigations showed that its internal structure is composed of cross-bedded loose layers and relatively thin tightly packed layers called bedding. Uniaxial compression tests were performed on different Berea sandstone specimens. The uniaxial compressive strength (UCS) decreases with increasing porosity, and also decreases with increasing inclination of the bedding plane relative to horizontal line. Two-dimensional discrete modeling was applied to investigate the micromechanical behavior of Berea sandstone. Different microparameters were assigned to loose and tight layers. The UCS simulation results agree well with the experimental results. At the peak stress, cracks almost always develop in loose layers regardless of the bedding plane orientation. In addition, both normal and shear cracks occur earlier for specimens with a higher inclination angle. No correlations were found between the inclination angle of failure planes and the orientation of bedding planes. The bedding planes of Berea sandstone are not weak planes. The strength anisotropy of Berea sandstone is not significant compared with other rocks such as shale, gneiss, and schist.

  17. Elastic moduli and strength of nanocrystalline cubic BC2N from x-ray diffraction under nonhydrostatic compression

    Science.gov (United States)

    Dong, Haini; He, Duanwei; Duffy, Thomas S.; Zhao, Yusheng

    2009-01-01

    The stress behavior of nanocrystalline cubic boron carbon nitride (c-BC2N) was investigated using radial and axial x-ray diffractions in the diamond-anvil cell under nonhydrostatic compression up to ~100 GPa. The radial x-ray diffraction (RXRD) data yield a bulk modulus K0=276±20GPa with a fixed pressure derivative K0'=3.4 at ψ=54.7° , which corresponds to the hydrostatic compression curve. The bulk modulus obtained from axial x-ray diffraction (AXRD) gives a value of 420±11GPa . A comparative study of the observed compression curves from radial and axial diffractions shows that the ruby-fluorescence pressure scale may reflect the maximum stress under nonhydrostatic compression. It was found that nanocrystalline c-BC2N sample could support a maximum differential stress of ~38 GPa when it started to yield at ~66 GPa under uniaxial compression. Moreover, the aggregate elastic moduli of the nanocrystalline c-BC2N have been determined from the RXRD data at high pressures.

  18. Application of Geostatistical Modelling to Study the Exploration Adequacy of Uniaxial Compressive Strength of Intact Rock alongthe Behesht-Abad Tunnel Route

    Directory of Open Access Journals (Sweden)

    Mohammad Doustmohammadi

    2014-12-01

    Full Text Available Uniaxial compressive strength (UCS is one of the most significant factors on the stability of underground excavation projects. Most of the time, this factor can be obtained by exploratory boreholes evaluation. Due to the large distance between exploratory boreholes in the majority of geotechnical projects, the application of geostatistical methods has increased as an estimator of rock mass properties. The present paper ties the estimation of UCS values of intact rock to the distance between boreholes of the Behesht-Abad tunnel in central Iran, using SGEMS geostatistical program. Variography showed that UCS estimation of intact rock using geostatistical methods is reasonable. The model establishment and validation was done after assessment that the model was trustworthy. Cross validation proved the high accuracy (98% and reliability of the model to estimate uniaxial compressive strength. The UCS values were then estimated along the tunnel axis. Moreover, using geostatistical estimation led to better identification of the pros and cons of geotechnical explorations in each location of tunnel route.

  19. Relationship between tensile strength and porosity for high porosity metals

    Institute of Scientific and Technical Information of China (English)

    刘培生; 付超; 李铁藩; 师昌绪

    1999-01-01

    An analysis model has been established according to the structure feature of high porosity metals, and the mathematical relationship between the tensile strength and porosity for this material has been derived from the model. Moreover, the corresponding theoretical formula has been proved good to reflect the variation law of tensile strength with porosity for high porosity metals by the example experiment on nickel foam.

  20. Fatigue-induced damage of high-strength steels

    Science.gov (United States)

    Shetulov, D. I.; Myl'nikov, V. V.

    2014-03-01

    The issues on the estimation of the surface damage of the products produced from high-strength alloys are considered. Mathematical relationships for a numerical calculation of the surface damage are given. The peculiarities of the evaluation of the surface damage are investigated, as applied to high-strength alloys.

  1. Ductile Bulk Aluminum-Based Alloy with Good Glass-Forming Ability and High Strength

    Institute of Scientific and Technical Information of China (English)

    ZHUO Long-Chao; PANG Shu-Jie; WANG Hui; ZHANG Tao

    2009-01-01

    Based on a new approach for designing glassy alloy compositions,bulk Al-based alloys with good glass-forming ability (GFA) are synthesized.The cast Al86Si0.5Ni4.06Co2.94 Y6Sc0.5 rod with a diameter of 1 mm shows almost fully amorphous structure besides about 5% fcc-Al nucleated in the center of the rod.The bulk alloy with high Al concentration exhibits an ultrahigh yield strength of 1.18 Gpa and maximum strength of 1.27 Gpa as well as an obvious plastic strain of about 2.4% during compressive deformation.This light Al-based alloy with good GFA and mechanical properties is promising as a new high specific strength material with good deformability.

  2. Strength of precast concrete shear joints reinforced with high-strength wire ropes

    DEFF Research Database (Denmark)

    Joergensen, Henrik B.; Hoang, Linh Cao; Hagsten, Lars German

    2017-01-01

    This paper concerns the in-plane shear strength of connections between precast concrete wall elements reinforced with looped high-strength wire ropes. The looped wire ropes are pre-installed in so-called ‘wire boxes’ which function as shear keys. Although only a small amount of research...... on the shear strength of such connections can be found in the literature, this type of connection is increasingly being used because wire ropes are much more construction-friendly than traditional U-bars. A rigid plastic upper bound model for the shear strength of wall connections reinforced with looped wire...... ropes that are pre-installed in wire boxes is presented along with test results on the shear strength of connections with double-wire boxes. It is shown that the plastic solution agrees well with both the obtained test results and results from previously conducted tests....

  3. Behavior Of A Confined Tension Lap Splice In High-Strength Reinforced Concrete Beams

    Science.gov (United States)

    Abdel-Kareem, Ahmed H.; Abousafa, Hala; El-Hadidi, Omaia S.

    2015-09-01

    The results of an experimental program conducted on seventeen simply supported concrete beams to study the effect of transverse reinforcement on the behavior of the lap splice of a steel reinforcement in tension zones in high-strength concrete beams are presented. The parameters included in the experimental program were the concrete compressive strength, the lap splice length, the amount of transverse reinforcement provided within the splice region, and the shape of the transverse reinforcement around the spliced bars. The experimental results showed that the displacement ductility increased and the mode of failure changed from a splitting bond failure to a flexural failure when the amount of the transverse reinforcement in the splice region increased, and the compressive strength increased up to 100 MPa. The presence of the transverse reinforcement around the spliced bars had a pronounced effect on increasing the ultimate load, the ultimate deflection, and the displacement ductility. The prediction of maximum steel stresses for spliced bars using the ACI 318-05 building code was compared with the experimental results. The comparison showed that the effect of the transverse reinforcement around spliced bars has to be considered into the design equations for lap splice length in high-strength concrete beams.

  4. Mechanical Properties of High Strength Concrete Containing Coal Bottom Ash and Oil-Palm Boiler Clinker as Fine Aggregates

    Directory of Open Access Journals (Sweden)

    Soofinajafi Mahmood

    2016-01-01

    Full Text Available This research aims to utilize Coal Furnace Bottom ash (CBA and Oil-Palm Boiler Clinker (OPBC as fine aggregate in concrete mix proportions. They are solid wastes from power plant and Oil Palm industry, respectively. Since these by-products do not have any primary use and are pure waste, an opportunity to use them as aggregate in concrete industry not only is economical but also will be an environmental friendly opportunity leading towards a more sustainable production chain. CBA and OPBC sands had similar grading to normal sand but have lower density and higher water absorption. In a high strength concrete, normal sand was replaced up to 25% with either CBA or OPBC. Test results showed that although water absorption of these wastes was more than normal sand but the slump value of concrete containing each of these wastes showed that these concretes had good workability. All mixes containing these wastes had slightly lower compressive strength at early ages and equivalent or higher compressive strength at later ages compared to control mix. The 28-day compressive strength of these concretes was in the range of 69–76 MPa which can be categorized as high strength concrete. In general, the performance of OPBC was better than CBA at 25% replacement level. However, it is recommended that at least 12.5% of total volume of fine aggregate in a high strength concrete is used of CBA or OPBC.

  5. The strength of single crystal copper under uniaxial shock compression at 100 GPa

    Science.gov (United States)

    Murphy, W. J.; Higginbotham, A.; Kimminau, G.; Barbrel, B.; Bringa, E. M.; Hawreliak, J.; Kodama, R.; Koenig, M.; McBarron, W.; Meyers, M. A.; Nagler, B.; Ozaki, N.; Park, N.; Remington, B.; Rothman, S.; Vinko, S. M.; Whitcher, T.; Wark, J. S.

    2010-02-01

    In situ x-ray diffraction has been used to measure the shear strain (and thus strength) of single crystal copper shocked to 100 GPa pressures at strain rates over two orders of magnitude higher than those achieved previously. For shocks in the [001] direction there is a significant associated shear strain, while shocks in the [111] direction give negligible shear strain. We infer, using molecular dynamics simulations and VISAR (standing for 'velocity interferometer system for any reflector') measurements, that the strength of the material increases dramatically (to ~1 GPa) for these extreme strain rates.

  6. Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions.

    Directory of Open Access Journals (Sweden)

    Xiaowei Feng

    Full Text Available Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three

  7. The Influence of GI and GII on the Compression After Impact Strength of Carbon Fiber/Epoxy Laminates and Sandwich Structure

    Science.gov (United States)

    Nettles, A. T.; Scharber, L. L.

    2017-01-01

    This study measured the compression after impact strength of IM7 carbon fiber laminates made from epoxy resins with various mode I and mode II toughness values to observe the effects of these toughness values on the resistance to damage formation and subsequent residual compression strength-carrying capabilities. Both monolithic laminates and sandwich structure were evaluated. A total of seven different epoxy resin systems were used ranging in approximate GI values of 245-665 J/sq m and approximate GII values of 840-2275 J/sq m. The results for resistance to impact damage formation showed that there was a direct correlation between GII and the planar size of damage, as measured by thermography. Subsequent residual compression strength testing suggested that GI had no influence on the measured values and most of the difference in compression strength was directly related to the size of damage. Thus, delamination growth assumed as an opening type of failure mechanism does not appear to be responsible for loss of compression strength in the specimens examined in this study.

  8. Modeling and analysis of porosity and compressive strength of gradient Al2O3-ZrO2 ceramic filter using BP neural network

    Directory of Open Access Journals (Sweden)

    Li Qiang

    2013-07-01

    Full Text Available BP neural network was used in this study to model the porosity and the compressive strength of a gradient Al2O3-ZrO2 ceramic foam filter prepared by centrifugal slip casting. The influences of the load applied on the epispastic polystyrene template (F, the centrifugal acceleration (v and sintering temperature (T on the porosity (P and compressive strength (σ of the sintered products were studied by using the registered three-layer BP model. The accuracy of the model was verified by comparing the BP model predicted results with the experimental ones. Results show that the model prediction agrees with the experimental data within a reasonable experimental error, indicating that the three-layer BP network based modeling is effective in predicting both the properties and processing parameters in designing the gradient Al2O3-ZrO2 ceramic foam filter. The prediction results show that the porosity percentage increases and compressive strength decreases with an increase in the applied load on epispastic polystyrene template. As for the influence of sintering temperature, the porosity percentage decreases monotonically with an increase in sintering temperature, yet the compressive strength first increases and then decreases slightly in a given temperature range. Furthermore, the porosity percentage changes little but the compressive strength first increases and then decreases when the centrifugal acceleration increases.

  9. Influence of artificially-induced porosity on the compressive strength of calcium phosphate bone cements.

    Science.gov (United States)

    Mouzakis, Dionysios; Zaoutsos, Stefanos Polymeros; Bouropoulos, Nikolaos; Rokidi, Stamatia; Papanicolaou, George

    2016-07-01

    The biological and mechanical nature of calcium phosphate cements (CPC's) matches well with that of bone tissues, thus they can be considered as an appropriate environment for bone repair as bone defect fillers. The current study focuses on the experimental characterization of the mechanical properties of CPCs that are favorably used in clinical applications. Aiming on evaluation of their mechanical performance, tests in compression loading were conducted in order to determine the mechanical properties of the material under study. In this context, experimental results occurring from the above mechanical tests on porous specimens that were fabricated from three different porous additives, namely albumin, gelatin and sodium alginate, are provided, while assessment of their mechanical properties in respect to the used porous media is performed. Additionally, samples reinforced with hydroxyapatite crystals were also tested in compression and the results are compared with those of the above tested porous CPCs. The knowledge obtained allows the improvement of their biomechanical properties by controlling their structure in a micro level, and finds a way to compromise between mechanical and biological response.

  10. Elevated Temperature, Residual Compressive Strength of Impact-Damaged Sandwich Structure Manufactured Out-of-Autoclave

    Science.gov (United States)

    Grimsley, Brian W.; Sutter, James K.; Burke, Eric R.; Dixon, Genevieve D.; Gyekenyesi, Thomas G.; Smeltzer, Stanley S.

    2012-01-01

    Several 1/16th-scale curved sandwich composite panel sections of a 10 m diameter barrel were fabricated to demonstrate the manufacturability of large-scale curved sections using minimum gauge, [+60/-60/0]s, toughened epoxy composite facesheets co-cured with low density (50 kilograms per cubic meters) aluminum honeycomb core. One of these panels was fabricated out of autoclave (OoA) by the vacuum bag oven (VBO) process using Cycom(Registered Trademark) T40-800b/5320-1 prepreg system while another panel with the same lay-up and dimensions was fabricated using the autoclave-cure, toughened epoxy prepreg system Cycom(Registered Trademark) IM7/977-3. The resulting 2.44 m x 2 m curved panels were investigated by non-destructive evaluation (NDE) at NASA Langley Research Center (NASA LaRC) to determine initial fabrication quality and then cut into smaller coupons for elevated temperature wet (ETW) mechanical property characterization. Mechanical property characterization of the sandwich coupons was conducted including edge-wise compression (EWC), and compression-after-impact (CAI) at conditions ranging from 25 C/dry to 150 C/wet. The details and results of this characterization effort are presented in this paper.

  11. High Strain Rate Compressive Tests on Woven Graphite Epoxy Composites

    Science.gov (United States)

    Allazadeh, Mohammad Reza; Wosu, Sylvanus N.

    2011-08-01

    The behavior of composite materials may be different when they are subjected to high strain rate load. Penetrating split Hopkinson pressure bar (P-SHPB) is a method to impose high strain rate on specimen in the laboratory experiments. This research work studied the response of the thin circular shape specimens, made out of woven graphite epoxy composites, to high strain rate impact load. The stress-strain relationships and behavior of the specimens were investigated during the compressive dynamic tests for strain rates as high as 3200 s-1. One dimensional analysis was deployed for analytical calculations since the experiments fulfilled the ratio of diameter to length of bars condition in impact load experiments. The mechanics of dynamic failure was studied and the results showed the factors which govern the failure mode in high strain deformation via absorbed energy by the specimen. In this paper, the relation of particle velocity with perforation depth was discussed for woven graphite epoxy specimens.

  12. High frequency chest compression therapy: a case study.

    Science.gov (United States)

    Butler, S; O'Neill, B

    1995-01-01

    A new device, the ThAIRapy Bronchial Drainage System, enables patients with cystic fibrosis to self-administer the technique of high frequency chest compression (HFCC) to assist with mucociliary clearance. We review the literature on HFCC and outline a case study of a patient currently using the ThAIRapy Bronchial Drainage System. While mucociliary clearance and lung function may be enhanced by HFCC therapy, more research is needed to determine its efficacy, cost benefits, and optimum treatment guidelines. Although our initial experience with the patient using this device has been positive, we were unable to accurately evaluate the ThAIRapy Bronchial Drainage System.

  13. Highly compressible fluorescent particles for pressure sensing in liquids

    Science.gov (United States)

    Cellini, F.; Peterson, S. D.; Porfiri, M.

    2017-05-01

    Pressure sensing in liquids is important for engineering applications ranging from industrial processing to naval architecture. Here, we propose a pressure sensor based on highly compressible polydimethylsiloxane foam particles embedding fluorescent Nile Red molecules. The particles display pressure sensitivities as low as 0.0018 kPa-1, which are on the same order of magnitude of sensitivities reported in commercial pressure-sensitive paints for air flows. We envision the application of the proposed sensor in particle image velocimetry toward an improved understanding of flow kinetics in liquids.

  14. Friction Stir Spot Welding of Advanced High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Santella, M. L.; Hovanski, Yuri; Grant, Glenn J.; Carpenter, Joseph A.; Warren, C. D.; Smith, Mark T.

    2008-12-28

    Experiments are continuing to evaluate the feasibility of friction stir spot welding advanced high-strength steels including, DP780, martensitic hot-stamp boron steel, and TRIP steels. Spot weld lap-shear strengths can exceed those required by industry standards such as AWS D8.1.

  15. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale

    Science.gov (United States)

    Hossain, R.; Pahlevani, F.; Quadir, M. Z.; Sahajwalla, V.

    2016-10-01

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels’ performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.

  16. Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale.

    Science.gov (United States)

    Hossain, R; Pahlevani, F; Quadir, M Z; Sahajwalla, V

    2016-10-11

    Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels' performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties.

  17. Investigation of the plastic fracture of high strength steels

    Science.gov (United States)

    Cox, T. B.; Low, J. R., Jr.

    1972-01-01

    This investigation deals in detail with the three recognized stages of plastic fracture in high strength steels, namely, void initiation, void growth, and void coalescence. The particular steels under investigation include plates from both commercial purity and high purity heats of AISI 4340 and 18 Ni, 200 grade maraging steels. A scanning electron microscope equipped with an X-ray energy dispersive analyzer, together with observations made using light microscopy, revealed methods of improving the resistance of high strength steels to plastic fracture.

  18. Effect of SrCO3 addition on the dynamic compressive strength of ZTA

    Institute of Scientific and Technical Information of China (English)

    Ali Arab; Roslan Ahmad; Zainal Arifin Ahmad

    2016-01-01

    Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics;thus, it is helpful to predict the dynamic strength of ceramics on the basis of their mechanical properties. In this paper, the addition of SrCO3 into zirconia-toughened alumina (ZTA) was demonstrated to improve the fracture toughness of ZTA due to the formation of the SrAl12O19 (SA6) phase. The porosity of ZTA was found to be increased by the addition of SrCO3. These newly formed pores served as the nucleation sites of cracks under dynamic load;these cracks eventually coalesced to form damaged zones in the samples. Although the KIC values of the samples were improved, the dynamic strength was not en-hanced because of the increase in porosity;in fact, the dynamic strength of ZTA ceramics decreased with the addition of SrCO3.

  19. Effect of tension lap splice on the behavior of high strength concrete (HSC beams

    Directory of Open Access Journals (Sweden)

    Ahmed El-Azab

    2014-12-01

    Full Text Available In the recent years, many research efforts have been carried out on the bond strength between normal strength concrete (NSC and reinforcing bars spliced in tension zones in beams. Many codes gave a minimum splice length for tension and compression reinforcement as a factor of the bar diameter depending on many parameters such as concrete strength, steel yield stress, shape of bar end, shape of bar surface and also bar location. Also, codes gave another restriction about the percentage of total reinforcement to be spliced at the same time. Comparatively limited attention has been directed toward the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. HSC has high modulus of elasticity, high density and long-term durability. This research presents an experimental study on the bond between high strength concrete (HSC and reinforcing bars spliced in tension zones in beams. It reports the influence of several parameters on bond in splices. The parameters covered are casting position, splice length as a factor of bar diameter, bar diameter and reinforcement ratio. The research involved tests on sixteen simply-supported beams of 1800 mm span, 200 mm width and 400 mm thickness made of HSC. In each beam, the total tensile steel bars were spliced in the constant moment zone. Crack pattern, crack propagation, cracking load, failure load and mi span deflection were recorded and analyzed to study the mentioned parameters effect.

  20. Corrosion Resistance of High Strength Concrete Containing Palm Oil Fuel Ash as Partial Cement Replacement

    Directory of Open Access Journals (Sweden)

    F. Mat Yahaya

    2014-06-01

    Full Text Available This experimental work investigates the influence of POFA as partial cement replacement towards corrosion resistance of high strength concrete. Plain high strength concrete (P0 with 100% ordinary Portland cement (control specimen and POFA high strength concrete containing POFA as partial cement replacement material were used. At the first stage, mix with 20% POFA (P20 has been identified as the best performing mix after cubes (150×150×150 mm containing various content of POFA as partial cement replacement were prepared, continuously water cured and subjected to compressive strength test at 28 days. At the second stage of study, control specimen (P0 and high strength concrete mix containing 20% POFA (P20 were prepared in form of cylinders with reinforcement bar buried in the middle for corrosion resistance test. Specimens were subjected to half cell potential technique following the procedures outlined in ASTM C876 (1994. Incorporation of POFA as partial cement replacement has contributed to densification of microstructure making the concrete denser thus exhibit higher resistance towards corrosion as compared to plain concrete.

  1. 高强度钢材工字形截面轴心受压短柱局部稳定试验研究%Experimental study on local buckling of high strength steel I-section stub columns under axial compression

    Institute of Scientific and Technical Information of China (English)

    施刚; 林错错; 王元清; 石永久

    2012-01-01

    针对高强度钢材焊接工字形截面轴心受压短柱的局部稳定性能,对9个Q460C工字形截面短柱进行轴心受压试验,分析试件局部屈曲应力、极限应力随板件宽厚比的变化规律,研究翼缘、腹板嵌固系数的取值。此外,将屈曲应力、极限应力试验结果与我国、美国和欧洲钢结构设计规范的相应设计计算结果进行对比分析,研究相应规范对于高强度钢材的适用性。结果表明:翼缘的嵌固系数可取为定值1.0,腹板的嵌固系数不宜取为定值;GB 50017—2003《钢结构设计规范》中关于高强度钢材工字形截面短柱的局部屈曲应力的计算结果是不合理的;AISC 360-05规范的极限应力计算值误差较大,但偏于保守;Eurocode 3规范的极限应力计算值与试验值较为接近,但大部分计算结果较试验值偏大。为此,建议提出新的公式计算工字形截面短柱的局部屈曲应力,而对Eurocode 3规范关于工字形截面短柱的极限应力计算公式进行修正,使其能适用于Q460C高强度钢材。%Aiming at the local buckling behavior of high strength steel welded I-section columns,9 axial compression tests of Q460C I-section stub columns were conducted.Based on the test results,the relation of buckling stress and ultimate stress of specimens with different width-to-thickness ratios were studied,and the clamping coefficients of flange and web were proposed.Besides,test results were compared with the corresponding design methods in Chinese,American and European steel structures design codes,to confirm whether the design methods can be used to calculate buckling stress and ultimate stress of Q460C I-section stub columns.The research work shows that the clamping coefficient of the flange is a fixed value 1.0,but web isn't a fixed value.The buckling stress of I-section stub columns achieved by the design method in the Chinese code is unreasonable.The ultimate stress achieved by the design method

  2. Effects of altered crystalline structure and increased initial compressive strength of calcium sulfate bone graft substitute pellets on new bone formation.

    Science.gov (United States)

    Urban, Robert M; Turner, Thomas M; Hall, Deborah J; Infanger, Susan I; Cheema, Naveed; Lim, Tae-Hong; Moseley, Jon; Carroll, Michael; Roark, Michael

    2004-01-01

    A new, modified calcium sulfate has been developed with a different crystalline structure and a compressive strength similar to many calcium phosphate materials, but with a resorption profile only slightly slower than conventional surgical-grade calcium sulfate. A canine bilateral defect model was used to compare restoration of defects treated with the modified calcium sulfate compared to treatment using conventional calcium sulfate pellets after 6, 13, and 26 weeks. The modified calcium sulfate pellets were as effective as conventional calcium sulfate pellets with regard to the area fraction and compressive strength of newly formed bone in the treated bone defects. Mechanical testing demonstrated that the initial compressive strength of the modified material was increased nearly three-fold compared to that of conventional surgical-grade calcium sulfate. This increase potentially allows for its use in a broader range of clinical applications, such as vertebral and subchondral defects.

  3. Contributions to the study of porosity in fly ash-based geopolymers. Relationship between degree of reaction, porosity and compressive strength

    Directory of Open Access Journals (Sweden)

    Y. Luna-Galiano

    2016-09-01

    Full Text Available The main contribution of this paper relates to the development of a systematic study involving a set of parameters which could potentially have an impact on geopolymer properties: curing temperature, type of activating solution, alkali metal in solution, incorporation of slag (Ca source and type of slag used. The microstructures, degrees of reaction, porosities and compressive strengths of geopolymers have been evaluated. Geopolymers prepared with soluble silicate presented a more compacted and closed structure, a larger amount of gel, lower porosity and greater compressive strength than those prepared with hydroxides. On the other hand, Na-geopolymers were more porous but more resistant than K-geopolymers. Although there is an inverse relation between degree of reaction and porosity, between compressive strength and porosity it is not always inversely proportional and could, in some cases, be masked by changes produced in other influencing parameters.

  4. Aging Behavior of High-Strength Al Alloy 2618 Produced by Selective Laser Melting

    Science.gov (United States)

    Casati, Riccardo; Lemke, Jannis Nicolas; Alarcon, Adrianni Zanatta; Vedani, Maurizio

    2017-02-01

    High Si-bearing Al alloys are commonly used in additive manufacturing, but they have moderate mechanical properties. New high-strength compositions are necessary to spread the use of additively manufactured Al parts for heavy-duty structural applications. This work focuses on the microstructure, mechanical behavior, and aging response of an Al alloy 2618 processed by selective laser melting. Calorimetric analysis, electron microscopy, and compression tests were performed in order to correlate the mechanical properties with the peculiar microstructure induced by laser melting and thermal treatments

  5. Autogenous Shrinkage of High Strength Lightweight Aggregate Concrete

    Institute of Scientific and Technical Information of China (English)

    DING Qingjun; TIAN Yaogang; WANG Fazhou; ZHANG Feng; HU Shuguang

    2005-01-01

    The characteristic of autogenous shrinkage ( AS ) and its effect on high strength lightweight aggregate concrete (HSLAC) were studied. The experimental results show that the main shrinkage of high strength concrete is AS and the amount of cement can affect the AS of HSLAC remarkably. At the early stage the AS of HSLAC is lower than that of high strength normal concrete, but it has a large growth at the later stage. The AS of high strength normal concrete becomes stable at 90d age, but HSLAC still has a high AS growth. It is found that adjusting the volume rate of lightweight aggregate, mixing with a proper dosage of fly ash and raising the water saturation degree of lightweight aggregate can markedly reduce the AS rate of HSLAC.

  6. The Effect of Pulp Industrial Waste as Chemical Admixture to Compressive Strength of Fly Ash Based Alkali Activated Materials

    Directory of Open Access Journals (Sweden)

    Harmaji Andrie

    2017-01-01

    Full Text Available Black liquor is a toxic by-product from industrial pulp manufacture. It contains sodium hydroxide that can be used as precursor activator for alkali activated material, which is an aluminosilicate material that can be prepared from thermal activation of solid material containing alumina and silica as precursor and alkali activator solution. In this work, alkali activated mortar was prepared by mixing fly ash as main precursors, aggregate, followed by addition of activator solution containing sodium hydroxide solution and waterglass, and chemical admixture which is lignin or black liquor. The best compressive strength was 34.40 MPa achieved in addition of 10 wt% of black liquor to alkali activated mortar. X-ray diffraction demonstrated the formation of albite in mortars, indicating that geopolymerization have been successfully formed. FTIR spectra showed the presence of siloxo and sialate peaks which commonly found in geopolymerization.

  7. Survey of Processing Methods for High Strength High Conductivity Wires for High Field Magnet Applications

    Energy Technology Data Exchange (ETDEWEB)

    Han, K.; Embury, J.D.

    1998-10-01

    This paper will deal with the basic concepts of attaining combination of high strength and high conductivity in pure materials, in-situ composites and macrocomposites. It will survey current attainments, and outline where some future developments may lie in developing wire products that are close to the theoretical strength of future magnet applications.

  8. Formability Characterization of a New Generation High Strength Steels

    Energy Technology Data Exchange (ETDEWEB)

    Sriram Sadagopan; Dennis Urban; Chris Wong; Mai Huang; Benda Yan

    2003-05-16

    Advanced high strength steels (AHSS) are being progressively explored by the automotive industry all around the world for cost-effective solutions to accomplish vehicle lightweighting, improve fuel economy, and consequently reduce greenhouse emissions. Because of their inherent high strength, attractive crash energy management properties, and good formability, the effective use of AHSS such as Duel Phase and TRIP (Transformation Induced Plasticity) steels, will significantly contribute to vehicle lightweighting and fuel economy. To further the application of these steels in automotive body and structural parts, a good knowledge and experience base must be developed regarding the press formability of these materials. This project provides data on relevant intrinsic mechanical behavior, splitting limits, and springback behavior of several lots of mild steel, conventional high strength steel (HSS), advanced high strength steel (AHSS) and ultra-high strength steel (UHSS), supplied by the member companies of the Automotive Applications Committee (AAC) of the American Iron and Steel Institute (AISI). Two lots of TRIP600, which were supplied by ThyssenKrupp Stahl, were also included in the study. Since sheet metal forming encompasses a very diverse range of forming processes and deformation modes, a number of simulative tests were used to characterize the forming behavior of these steel grades. In general, it was found that formability, as determined by the different tests, decreased with increased tensile strength. Consistant with previous findings, the formability of TRIP600 was found to be exceptionally good for its tensile strength.

  9. Review on permeability of high-strength concrete subjected to high temperature

    Science.gov (United States)

    Zhao, Dongfu; Han, Xiao; Liu, Yuchen

    2017-08-01

    In this paper, the research results of permeability of high-strength concrete subjected to high temperature were comprehensively reviewed, the research status of permeability of high-strength concrete at elevated temperature were discussed, and existing problems were analyzed, finally, main research directions of permeability of high-strength concrete subjected to high temperature were forecasted.

  10. Fatigue strength of truss girders made of very high strength steel

    NARCIS (Netherlands)

    Pijpers, R.J.M.; Kolstein, M.H.

    2010-01-01

    An effective application of Very High Strength Steel (VHSS) in civil engineering structures is expected in stiff, truss like structures, typically made of Circular Hollow Sections (CHS). Use of castings in combination with CHS could be promising for the design of highly fatigue resistant joints. Cas

  11. Data Compression on Zero Suppressed High Energy Physics Data

    CERN Document Server

    Schindler, M; CERN. Geneva

    1996-01-01

    Future High Energy Physics experiments will produce unprecedented data volumes (up to 1 GB/s [1]). In most cases it will be impossible to analyse these data in real time and they will have to be stored on durable mostly magnetic linear media (e.g. tapes) for later analysis. This threatens to become a major cost factor for the running of these experiments. Here we present some ideas developed together with the Institute of Computer Graphics, Department for Algorithms and Programming on how this volume and the related cost can be reduced significantly. The algorithms presented are not general ones but aimed in particular to physics experiments data. Taking advantage of the knowledge of the data they are highly superior to general ones (Huffman, LZW, arithmetic coding) both in compression rate but more importantly in speed as to keep up with the output rate to modern tape drives. Above standard algorithms are, however, used after the data have been transferred in a more 'compressible' data space. These algorithm...

  12. THE TURBULENT DYNAMO IN HIGHLY COMPRESSIBLE SUPERSONIC PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Federrath, Christoph [Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia); Schober, Jennifer [Universität Heidelberg, Zentrum für Astronomie, Institut für Theoretische Astrophysik, Albert-Ueberle-Strasse 2, D-69120 Heidelberg (Germany); Bovino, Stefano; Schleicher, Dominik R. G., E-mail: christoph.federrath@anu.edu.au [Institut für Astrophysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, D-37077 Göttingen (Germany)

    2014-12-20

    The turbulent dynamo may explain the origin of cosmic magnetism. While the exponential amplification of magnetic fields has been studied for incompressible gases, little is known about dynamo action in highly compressible, supersonic plasmas, such as the interstellar medium of galaxies and the early universe. Here we perform the first quantitative comparison of theoretical models of the dynamo growth rate and saturation level with three-dimensional magnetohydrodynamical simulations of supersonic turbulence with grid resolutions of up to 1024{sup 3} cells. We obtain numerical convergence and find that dynamo action occurs for both low and high magnetic Prandtl numbers Pm = ν/η = 0.1-10 (the ratio of viscous to magnetic dissipation), which had so far only been seen for Pm ≥ 1 in supersonic turbulence. We measure the critical magnetic Reynolds number, Rm{sub crit}=129{sub −31}{sup +43}, showing that the compressible dynamo is almost as efficient as in incompressible gas. Considering the physical conditions of the present and early universe, we conclude that magnetic fields need to be taken into account during structure formation from the early to the present cosmic ages, because they suppress gas fragmentation and drive powerful jets and outflows, both greatly affecting the initial mass function of stars.

  13. Fracture Energy-Based Brittleness Index Development and Brittleness Quantification by Pre-peak Strength Parameters in Rock Uniaxial Compression

    Science.gov (United States)

    Munoz, H.; Taheri, A.; Chanda, E. K.

    2016-12-01

    Brittleness is a fundamental mechanical rock property critical to many civil engineering works, mining development projects and mineral exploration operations. However, rock brittleness is a concept yet to be investigated as there is not any unique criterion available, widely accepted by rock engineering community able to describe rock brittleness quantitatively. In this study, new brittleness indices were developed based on fracture strain energy quantities obtained from the complete stress-strain characteristics of rocks. In doing so, different rocks having unconfined compressive strength values ranging from 7 to 215 MPa were examined in a series of quasi-static uniaxial compression tests after properly implementing lateral-strain control in a closed-loop system to apply axial load to rock specimen. This testing method was essential to capture post-peak regime of the rocks since a combination of class I-II or class II behaviour featured post-peak stress-strain behaviour. Further analysis on the post-peak strain localisation, stress-strain characteristics and the fracture pattern causing class I-II and class II behaviour were undertaken by analysing the development of field of strains in the rocks via three-dimensional digital image correlation. Analysis of the results demonstrated that pre-peak stress-strain brittleness indices proposed solely based on pre-peak stress-strain behaviour do not show any correlation with any of pre-peak rock mechanical parameters. On the other hand, the proposed brittleness indices based on pre-peak and post-peak stress-strain relations were found to competently describe an unambiguous brittleness scale against rock deformation and strength parameters such as the elastic modulus, the crack damage stress and the peak stress relevant to represent failure process.

  14. Use of steel fibres recovered from waste tyres as reinforcement in concrete: pull-out behaviour, compressive and flexural strength.

    Science.gov (United States)

    Aiello, M A; Leuzzi, F; Centonze, G; Maffezzoli, A

    2009-06-01

    The increasing amount of waste tyres worldwide makes the disposition of tyres a relevant problem to be solved. In the last years over three million tons of waste tyres were generated in the EU states [ETRA, 2006. Tyre Technology International - Trends in Tyre Recycling. http://www.etra-eu.org]; most of them were disposed into landfills. Since the European Union Landfill Directive (EU Landfill, 1999) aims to significantly reduce the landfill disposal of waste tyres, the development of new markets for the tyres becomes fundamental. Recently some research has been devoted to the use of granulated rubber and steel fibres recovered from waste tyres in concrete. In particular, the concrete obtained by adding recycled steel fibres evidenced a satisfactory improvement of the fragile matrix, mostly in terms of toughness and post-cracking behaviour. As a consequence RSFRC (recycled steel fibres reinforced concrete) appears a promising candidate for both structural and non-structural applications. Within this context a research project was undertaken at the University of Salento (Italy) aiming to investigate the mechanical behaviour of concrete reinforced with RSF (recycled steel fibres) recovered from waste tyres by a mechanical process. In the present paper results obtained by the experimental work performed up to now are reported. In order to evaluate the concrete-fibres bond characteristics and to determine the critical fibre length, pull-out tests were initially carried out. Furthermore compressive strength of concrete was evaluated for different volume ratios of added RSF and flexural tests were performed to analyze the post-cracking behaviour of RSFRC. For comparison purposes, samples reinforced with industrial steel fibres (ISF) were also considered. Satisfactory results were obtained regarding the bond between recycled steel fibres and concrete; on the other hand compressive strength of concrete seems unaffected by the presence of fibres despite their irregular

  15. Initial Results on Neutralized Drift Compression Experiments (NDCX-IA) for High Intensity Ion Beam

    CERN Document Server

    Roy, Prabir K; Baca, David; Bieniosek, Frank; Coleman, Joshua E; Davidson, Ronald C; Efthimion, Philip; Eylon, Shmuel; Gilson, Erik P; Grant Logan, B; Greenway, Wayne; Henestroza, Enrique; Kaganovich, Igor D; Leitner, Matthaeus; Rose, David; Sefkow, Adam; Sharp, William M; Shuman, Derek; Thoma, Carsten H; Vanecek, David; Waldron, William; Welch, Dale; Yu, Simon

    2005-01-01

    Ion beam neutralization and compression experiments are designed to determine the feasibility of using compressed high intensity ion beams for high energy density physics (HEDP) experiments and for inertial fusion power. To quantitatively ascertain the various mechanisms and methods for beam compression, the Neutralized Drift Compression Experiment (NDCX) facility is being constructed at Lawrence Berkeley National Laboratory (LBNL). In the first compression experiment, a 260 KeV, 25 mA, K+ ion beam of centimeters size is radially compressed to a mm size spot by neutralization in a meter-long plasma column and beam peak current is longitudinally compressed by an induction velocity tilt core. Instrumentation, preliminary results of the experiments, and practical limits of compression are presented. These include parameters such as emittance, degree of neutralization, velocity tilt time profile, and accuracy of measurements (fast and spatially high resolution diagnostic) are discussed.

  16. High-strength braze joints between copper and steel

    Science.gov (United States)

    Kuhn, R. F.

    1967-01-01

    High-strength braze joints between copper and steel are produced by plating the faying surface of the copper with a layer of gold. This reduces porosity in the braze area and strengthens the resultant joint.

  17. Retention of ductility in high-strength steels

    Science.gov (United States)

    Parker, E. R.; Zackay, V. F.

    1969-01-01

    To produce high strength alloy steel with retention of ductility, include tempering, cooling and subsequent tempering. Five parameters for optimum results are pretempering temperature, amount of strain, strain rate, temperature during strain, and retempering temperature.

  18. Behaviour of high strength steel moment joints

    NARCIS (Netherlands)

    Girão Coelho, A.M.; Bijlaard, F.S.K.

    2010-01-01

    The design of joints to European standard EN 1993 within the semi-continuous/partially restrained philosophy is restricted to steel grades up to S460. With the recent development of high performance steels, the need for these restrictions should be revisited. The semicontinuous joint modelling can b

  19. Modeling of Compressive Strength Parallel to Grain of Heat Treated Scotch Pine (Pinus sylvestris L. Wood by Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Fatih Yapıcı

    2016-01-01

    Full Text Available In this study, the compressive strength of heat treated Scotch Pine was modeled using artificial neural network. The compressive strength (CS value parallel to grain was determined after exposing the wood to heat treatment at temperature of 130, 145, 160, 175, 190 and 205ºC for 3, 6, 9, 12 hours. The experimental data was evaluated by using multiple variance analysis. Secondly, the effect of heat treatment on the CS of samples was modeled by using artificial neural network (ANN.

  20. Strength and stability analysis of a single-walled black phosphorus tube under axial compression

    Science.gov (United States)

    Cai, Kun; Wan, Jing; Wei, Ning; Qin, Qing H.

    2016-07-01

    Few-layered black phosphorus materials currently attract much attention due to their special electronic properties. As a consequence, a single-layer black phosphorus (SLBP) nanotube has been theoretically built. The corresponding electronic properties of such a black phosphorus nanotube (BPNT) were also evaluated numerically. However, unlike graphene formed with 2sp2 covalent carbon atoms, SLBP is formed with 3sp3 bonded atoms. It means that the structure from SLBP will possess lower Young’s modulus and mechanical strength than those of carbon nanotubes. In this study, molecular dynamics simulation is performed to investigate the strength and stability of BPNTs affected by the factors of diameter, length, loading speed and temperature. Results are fundamental for investigating the other physical properties of a BPNT acting as a component in a nanodevice. For example, buckling of the BPNT happens earlier than fracture, before which the nanostructure has very small axial strain. For the same BPNT, a higher load speed results in lower critical axial strain and a nanotube with lower axial strain can still be stable at a higher temperature.