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1

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

International Nuclear Information System (INIS)

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 250C and 1000C; time, 3.5 x 103s and 950 x 103s (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 10-5s-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

2

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1987-01-01

3

Prediction of the unconfined compressive strength of compacted granular soils by using inference systems  

Science.gov (United States)

Adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) models have been extensively used to predict different soil properties in geotechnical applications. In this study, it was aimed to develop ANFIS and ANN models to predict the unconfined compressive strength (UCS) of compacted soils. For this purpose, 84 soil samples with different grain-size distribution compacted at optimum water content were subjected to the unconfined compressive tests to determine their UCS values. Many of the test results (for 64 samples) were used to train the ANFIS and the ANN models, and the rest of the experimental results (for 20 samples) were used to predict the UCS of compacted samples. To train these models, the clay content, fine silt content, coarse silt content, fine sand content, middle sand content, coarse sand content, and gravel content of the total soil mass were used as input data for these models. The UCS values of compacted soils were output data in these models. The ANFIS model results were compared with those of the ANN model and it was seen that the ANFIS model results were very encouraging. Consequently, the results of this study have important findings indicating reliable and simple prediction tools for the UCS of compacted soils.

Kalkan, Ekrem; Akbulut, Suat; Tortum, Ahmet; Celik, Samet

2009-10-01

4

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

Energy Technology Data Exchange (ETDEWEB)

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 potential for erosion, it is important to compare the measured shear strength to penetrometer measurements and to develop a correlation (or correlations) between UCS measured by a pocket penetrometer and direct shear strength measurements for various homogeneous and heterogeneous simulants. This study developed 11 homogeneous simulants, whose shear strengths vary from 4 to 170 kPa. With these simulants, we developed correlations between UCS measured by a Geotest E-280 pocket penetrometer and shear strength values measured by a Geonor H-60 hand-held vane tester and a more sophisticated bench-top unit, the Haake M5 rheometer. This was achieved with side-by-side measurements of the shear strength and UCS of the homogeneous simulants. The homogeneous simulants developed under this study consist of kaolin clay, plaster of Paris, and amorphous alumina CP-5 with water. The simulants also include modeling clay. The shear strength of most of these simulants is sensitive to various factors, including the simulant size, the intensity of mixing, and the curing time, even with given concentrations of simulant components. Table S.1 summarizes these 11 simulants and their shear strengths.

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

2011-02-20

5

Influence of mica on unconfined compressive strength of a cement-treated weathered granite gravel  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english The road construction industry faces a shortage of naturally occurring gravel materials that meet the requirements for base or even at times sub-base quality. This situation is exacerbated in some cases by the occurrence of mica in soils. This is reported to significantly affect the engineering prop [...] erties of materials, including plasticity index and compacted density. The objective of this paper is to investigate the influence of mica on the unconfined compressive strength (UCS) and volumetric changes of a cement-treated gravel material. Free mica (muscovite) was added in predetermined percentages by mass to neat gravel (G5) and specimens subjected to a series of standard laboratory tests. The results show that UCS of greater than 3 MPa is achievable by stabilising less than 5% mica content gravel material with at least 4% cement. Mica content beyond 10% results in very low UCS, even for cement content greater than 6%.

M R, Mshali; A T, Visser.

6

Correlation of slake durability index with unconfined compressive strength estimated through indirect methods for carbonate rocks of salt range, pakistan  

International Nuclear Information System (INIS)

In evaluation of engineering behavior of rock mass and rock materials, slaking of rocks is an important consideration. For the construction industry, a durable rock is usually preferred. About 75% of the rocks outcropping on continents are sedimentary rocks. To determine rock strength and deformation, direct tests such as uniaxial compressive strength are expensive and require considerable time. Hence there is need to explore relations through other indirect methods such as Slake Durability Index, Point Load Strength and Schmidt rebound hammer test. To investigate the correlation between Slake Durability and strength, multidisciplinary approach was adopted. For this study, one of the important industrial rock groups belonging to carbonate geology of Salt Range was selected. The Slake Durability Index test was performed on 32 rock samples collected from different parts of Salt Range and the test results were compared with indirect strength such as Point Load Strength and Schmidt Hammer Hardness. Data was statistically analyzed through linear regression analysis to determine the correlation coefficient and the variability of results for each test. A strong linear correlation of 1st cycle Slake Durability Index exists with Point Load Strength and Schmidt Hammer Hardness. (author)

7

Behavior of Stabilized Peat Soils in Unconfined Compression Tests  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Deep stabilized peat columns were known to be economical at forming foundations to support highway embankments constructed on deep peat land. However, failure in the formation of the columns with adequate strength was often attributed to unsuitable type and insufficient dosage of binder added to the soil. Organic matter in peat was known to impede the cementing process in the soil, thus retarding the early strength gain of stabilized peat. Approach: To evaluate the strength characteristics of stabilized peat, laboratory investigation on early strength gain of the stabilized soil was conducted to formulate a suitable and economical mix design that could be effectively used for the soil stabilization. To achieve such purpose, the study examined the effect of binder, sodium chloride as cement accelerator and siliceous sand as filler on the unconfined compressive strength of stabilized peat soils after 7 days of curing. Binders used to stabilize the peat were Ordinary Portland cement, ground granulated blast furnace slag, sodium bentonite, kaolinite, lime and bentonite. All the stabilized peat specimens were tested using unconfined compression apparatus. Results: The test results revealed that the stabilized peat specimen (80% OPC: 10% GGBS: 10% SB with addition of 4% sodium chloride by weight of binder and 50% well graded siliceous sand by volume of wet peat at 300 kg m-3 binder dosage yielded the highest unconfined compressive strength of 196 kPa. Such finding implied that the higher the dosage of siliceous sand in stabilized peat, the more solid particles were available for the binder to unite and form a load sustainable stabilized peat. Conclusions/Recommendations: It could be summarized that as the rate of hydration process of stabilized peat was accelerated by inclusion of sodium chloride, the solid particles contributed to the hardening of stabilized peat by providing the cementation bonds to form between contact points of the particles.

Wong L. Sing

2008-01-01

8

Determination of Friction Coefficient in Unconfined Compression of Brain Tissue  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Unconfined compression tests are more convenient to perform on cylindrical samples of brain tissue than tensile tests in order to estimate mechanical properties of the brain tissue because they allow for homogeneous deformations. The reliability of these tests depends significantly on the amount of friction generated at the specimen/platen interface. Thus, there is a crucial need to find an approximate value of the friction coefficient in order to predict a possible overesti...

Rashid, Badar; Destrade, Michel; Gilchrist, M. D.

2013-01-01

9

DEVELOPMENT OF EXPERIMENTAL CORRELATIONS BETWEEN INDENTATION PARAMETERS AND UNCONFINED COMPRESSIVE STRENGTH (UCS) VALUES IN SHALE SAMPLES / DESARROLO DE CORRELACIONES EXPERIMENTALES ENTRE PÁRAMETROS DE IDENTACIÓN Y LA RESISTENCIA COMPRENSIVA UNIAXIAL (UCS) PARA MUESTRAS DE SHALE  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish La Resistencia Compresiva Uniaxial (UCS), es una de las propiedades mecánicas de las rocas que se debe tener en cuenta durante las operaciones de perforación para evitar la inestabilidad de pozos (Abass H., A. et al. 2006). Durante las operaciones de perforación el UCS de las formaciones es la varia [...] ble de más alta influencia por encima de factores como el azimut, la inclinación, el tiempo de exposición e incluso el peso del lodo de perforación (Jaramillo, 2004). La técnica de Indentación ha demostrado en los últimos años ser adecuada para ayudar a determinar la resistencia de las rocas en tiempo real durante la perforación de pozos, mediante la implementación de correlaciones que permitan evaluar el UCS a partir de los parámetros de Indentación conocidos como Módulo de Indentación (IM) y Fuerza Crítica de Transición (CTF), medidas en pequeños fragmentos de roca obtenidos de la perforación de pozos. La resistencia de los shales ha demostrado ser muy problemática durante la perforación. Por este motivo el principal objetivo de este trabajo es encontrar correlaciones experimentales que permitan modelar la resistencia de la roca a través de la aplicación de la técnica de indentacion a muestras de roca. Lo interesante de esta técnica es la posibilidad de obtener propiedades de resistencia en tiempo real durante la perforación, incluyendo esas secciones del reservorio en las que no existen registros directos UCS ni mediciones indirectas. Con el fin de desarrollar las correlaciones experimentales se realizaron ocho pruebas de Compresión Uniaxial (no confinada) sobre cilindros de roca (plugs) extraídos de muestras de afloramiento de la formación Paja. A la vez re realizaron 200 pruebas de Indentación sobre fragmentos de shale extraídos de los alrededores de cada plug simulando los ripios que se obtienen de la perforación de pozos. Los resultados de ambas pruebas fueron correlacionados por medio de la técnica de mínimos cuadrados y se buscó la mejor correlación que representara el comportamiento de los resultados, permitiendo así obtener dos correlaciones polinomiales de segundo grado. Se determinaron coeficientes de correlación de 0,6513 para la correlación IM-UCS y 0,8111 para la correlación CTF-UCS, mostrando así que la mayor correlacionalidad entre parámetros de indentación y el UCS se da con el parámetro de Indentación conocido como Fuerza Critica de Transición (CTF). Abstract in english Unconfined Compressive Strength (UCS) is one of the rock mechanical properties that is important take into account during drilling operations in order to avoid wellbore instability. During drilling operations, UCS variability influences wellbore stability more than other factors such as azimuth, slo [...] pe, exposure time, and mud weight (Jaramillo, 2004). In last years, the indentation technique has been demonstrated to be an appropriate method for determining rock strength in real time during oil well drilling. This technique implements correlation that allow UCS evaluation from indentation parameters such as Indentation Module (IM) and Critical Transition Force (CTF), that can be measured on small rock fragments obtained during drilling. Shale formations in well drilling have demonstrated to be a hindrance since they represent the most important problem in reservoir stability (Abass, H., A. et al. 2006). Therefore, the main objective of this article is to find experimental correlations that allow the modeling of rock strength by applying the indentation technique to reservoir plug. The importance of this technique is the possibility to get rock strength properties in real time during drilling operations, although, those reservoir sections which do not have neither direct UCS records nor indirect measurements. Eight Unconfined Compression Tests (UCS) on rock cylinders (plugs) extracted from the Paja formation upwelling were conducted in order to develop the corresponding experimental correlations. Two hundred

Ricardo-Andrés, García; Néstor-Fernando, Saavedra; Zuly, Calderón-Carrillo; Darwin, Mateus.

2008-12-01

10

Determination of friction coefficient in unconfined compression of brain tissue.  

Science.gov (United States)

Unconfined compression tests are more convenient to perform on cylindrical samples of brain tissue than tensile tests in order to estimate mechanical properties of the brain tissue because they allow homogeneous deformations. The reliability of these tests depends significantly on the amount of friction generated at the specimen/platen interface. Thus, there is a crucial need to find an approximate value of the friction coefficient in order to predict a possible overestimation of stresses during unconfined compression tests. In this study, a combined experimental-computational approach was adopted to estimate the dynamic friction coefficient ? of porcine brain matter against metal platens in compressive tests. Cylindrical samples of porcine brain tissue were tested up to 30% strain at variable strain rates, both under bonded and lubricated conditions in the same controlled environment. It was established that ? was equal to 0.09±0.03, 0.18±0.04, 0.18±0.04 and 0.20±0.02 at strain rates of 1, 30, 60 and 90/s, respectively. Additional tests were also performed to analyze brain tissue under lubricated and bonded conditions, with and without initial contact of the top platen with the brain tissue, with different specimen aspect ratios and with different lubricants (Phosphate Buffer Saline (PBS), Polytetrafluoroethylene (PTFE) and Silicone). The test conditions (lubricant used, biological tissue, loading velocity) adopted in this study were similar to the studies conducted by other research groups. This study will help to understand the amount of friction generated during unconfined compression of brain tissue for strain rates of up to 90/s. PMID:23026694

Rashid, Badar; Destrade, Michel; Gilchrist, Michael D

2012-10-01

11

Determination of Friction Coefficient in Unconfined Compression of Brain Tissue  

CERN Document Server

Unconfined compression tests are more convenient to perform on cylindrical samples of brain tissue than tensile tests in order to estimate mechanical properties of the brain tissue because they allow for homogeneous deformations. The reliability of these tests depends significantly on the amount of friction generated at the specimen/platen interface. Thus, there is a crucial need to find an approximate value of the friction coefficient in order to predict a possible overestimation of stresses during unconfined compression tests. In this study, a combined experimental-computational approach was adopted to estimate the dynamic friction coefficient mu of porcine brain matter against metal platens in compressive tests. Cylindrical samples of porcine brain tissue were tested up to 30% strain at variable strain rates, both under bonded and lubricated conditions in the same controlled environment. It was established that mu was equal to 0.09 +/- 0.03, 0.18 +/- 0.04, 0.18 +/- 0.04 and 0.20 +/- 0.02 at strain rates of...

Rashid, Badar; Gilchrist, Michael; 10.1016/j.jmbbm.2012.05.001

2013-01-01

12

Viscoelastic characterisation of pig liver in unconfined compression.  

Science.gov (United States)

Understanding and modelling liver biomechanics represents a significant challenge due to the complex nature of this organ. Unfortunately, there is no consensus on liver viscoelastic properties, and results are strongly dependent on sample type and status, adopted testing method, and testing conditions. Standard force-triggered tests (e.g. step response or dynamic mechanical tests) necessitate an initial contact between sample and testing apparatus, which may result in significant pre-stress to very soft and highly hydrated samples. In a previous study we proposed the epsilon dot method (??M): a testing and analysis framework to address the drawbacks of standard mechanical tests. Focusing on ex-vivo unconfined bulk compressive tests, here we use both the ??M and dynamic mechanical analysis (DMA) to derive liver viscoelastic parameters in the region of small strains or the linear viscoelastic region (LVR). As liver samples were visibly deteriorated at the end of frequency sweep tests, a modified approach was adopted to reduce DMA testing times. This approach, termed step-reconstructed DMA (SRDMA), is based on dynamic measurements around specific frequencies and then reconstruction of liver behaviour in the entire frequency range of interest. The instantaneous elastic modulus obtained from SRDMA tests (2.65 ± 0.30 kPa) was significantly higher than that obtained with the ??M (2.04 ± 0.01 kPa). We show that the overestimation of stiffness is due to data acquisition in a local rather than an absolute LVR, highlighting the importance of using a rapid and zero pre-stress approach to characterise very soft and highly hydrated biological tissues. PMID:25017301

Mattei, G; Tirella, A; Gallone, G; Ahluwalia, A

2014-08-22

13

Sinusoidally-driven unconfined compression test for a biphasic tissue  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In recent years, a number of experimental studies have been conducted to investigate the mechanical behavior of water-saturated biological tissues like articular cartilage under dynamic loading. For in vivo measurements of tissue viability, the indentation tests with the half-sinusoidal loading history were proposed. In the present paper, the sinusoidally-driven compression test utilizing either the load-controlled or displacement-controlled loading protocol are considered i...

Argatov, Ivan

2012-01-01

14

Effects of friction on the unconfined compressive response of articular cartilage: a finite element analysis.  

Science.gov (United States)

A finite element analysis is used to study a previously unresolved issue of the effects of platen-specimen friction on the response of the unconfined compression test; effects of platen permeability are also determined. The finite element formulation is based on the linear KLM biphasic model for articular cartilage and other hydrated soft tissues. A Galerkin weighted residual method is applied to both the solid phase and the fluid phase, and the continuity equation for the intrinsically incompressible binary mixture is introduced via a penalty method. The solid phase displacements and fluid phase velocities are interpolated for each element in terms of unknown nodal values, producing a system of first order differential equations which are solved using a standard numerical finite difference technique. An axisymmetric element of quadrilateral cross-section is developed and applied to the mechanical test problem of a cylindrical specimen of soft tissue in unconfined compression. These studies show that interfacial friction plays a major role in the unconfined compression response of articular cartilage specimens with small thickness to diameter ratios. PMID:2345443

Spilker, R L; Suh, J K; Mow, V C

1990-05-01

15

A fibril-network-reinforced biphasic model of cartilage in unconfined compression.  

Science.gov (United States)

Cartilage mechanical function relies on a composite structure of a collagen fibrillar network entrapping a proteoglycan matrix. Previous biphasic or poroelastic models of this tissue, which have approximated its composite structure using a homogeneous solid phase, have experienced difficulties in describing measured material responses. Progress to date in resolving these difficulties has demonstrated that a constitutive low that is successful for one test geometry (confined compression) is not necessarily successful for another (unconfined compression). In this study, we hypothesize that an alternative fibril-reinforced composite biphasic representation of cartilage can predict measured material responses and explore this hypothesis by developing and solving analytically a fibril-reinforced biphasic model for the case of uniaxial unconfined compression with frictionless compressing platens. The fibrils were considered to provide stiffness in tension only. The lateral stiffening provided by the fibril network dramatically increased the frequency dependence of disk rigidity in dynamic sinusoidal compression and the magnitude of the stress relaxation transient, in qualitative agreement with previously published data. Fitting newly obtained experimental stress relaxation data to the composite model allowed extraction of mechanical parameters from these tests, such as the rigidity of the fibril network, in addition to the elastic constants and the hydraulic permeability of the remaining matrix. Model calculations further highlight a potentially important difference between homogeneous and fibril-reinforced composite models. In the latter type of model, the stresses carried by different constituents can be dissimilar, even in sign (compression versus tension) even though strains can be identical. Such behavior, resulting only from a structurally physiological description, could have consequences in the efforts to understand the mechanical signals that determine cellular and extracellular biological responses to mechanical loads in cartilage. PMID:10396701

Soulhat, J; Buschmann, M D; Shirazi-Adl, A

1999-06-01

16

Unconfined compression experiments on Topopah Spring Member tuff at 22 degrees C and a strain rate of 10-9 s-1: Data report  

International Nuclear Information System (INIS)

Experiment results are presented for unconfined compressive strength and elastic moduli of tuffaceous rocks from Busted Butte near Yucca Mountain, Nevada. The data have been compiled for the Yucca Mountain Site Characterization Project Site and Engineering Properties Data Base. Experiments were conducted on water-saturated specimens of the potential nuclear waste repository horizon Topopah Spring Member tuff (thermal/mechanical unit TSw2). The influence of strain rate on mechanical properties of the tuff was examined by loading six specimens in uniaxial compression at a strain rate of 10-9 s-1. The experiments performed under ambient pressure and temperature conditions and conformed to Technical Procedure 91, titled ''Unconfined Compression Experiments at 22 degrees C and a Strain Rate of 10-9 s-1.'' The mean and standard deviation values of ultimate strength, Young's modulus and Poisson's ratio determined from these experiments are 85.4±21.7 MPa, 33.9±4.6 GPa, and 0.09±0.07, respectively

17

A biphasic multiscale study of the mechanical microenvironment of chondrocytes within articular cartilage under unconfined compression.  

Science.gov (United States)

Computational analyses have been used to study the biomechanical microenvironment of the chondrocyte that cannot be assessed by in vitro experimental studies; yet all computational studies thus far have focused on the effect of zonal location (superficial, middle, and deep) on the mechanical microenvironment of chondrocytes. The aim of this paper was to study the effect of both zonal and radial locations on the biomechanical microenvironment of chondrocytes in inhomogeneous cartilage under unconfined stress relaxation. A biphasic multiscale approach was employed and nine chondrocytes in different locations were studied. Hyperelastic biphasic theory and depth-dependent aggregate modulus and permeability of articular cartilage were included in the models. It was found that both zonal and radial locations affected the biomechanical stresses and strains of the chondrocytes. Chondrocytes in the mid-radial location had increased volume during the early stage of the loading process. Maximum principal shear stress at the interface between the chondrocyte and the extracellular matrix (ECM) increased with depth, yet that at the ECM-pericellular matrix (PCM) interface had an inverse trend. Fluid pressure decreased with depth, while the fluid pressure difference between the top and bottom boundaries of the microscale model increased with depth. Regardless of location, fluid was exchanged between the chondrocyte, PCM, and ECM. These findings suggested that even under simple compressive loading conditions, the biomechanical microenvironment of the chondrocytes, PCM and ECM was spatially dependent. The current study provides new insight on chondrocyte biomechanics. PMID:24882738

Guo, Hongqiang; Maher, Suzanne A; Torzilli, Peter A

2014-08-22

18

Material properties in unconfined compression of gelatin hydrogel for skin tissue engineering applications.  

Science.gov (United States)

Abstract Gelatin (Gel) has been reported as a promising candidate in tissue engineering owing to its easy availability, biocompatibility, and biodegradability. Gel hydrogel is of potential to be cross-linked with different materials to enhance their biocompatibility for cell culture for tissue engineering applications. The mechanical properties of this versatile material, however, have not been thoroughly determined. In this study, the linear elastic (Young's modulus and maximum stress) and non-linear hyperelastic (hyperelastic coefficients) mechanical properties of prepared hydrogels at different contents of Gel (wt%) were measured, and its Young's modulus was compared with that of skin tissue. The prepared cylindrical Gel hydrogels were subjected to a series of unconfined compression tests. The hyperelastic strain energy density function was calibrated using the compressive experimental data. The potential ability of the Yeoh hyperelastic constitutive equation, which has been proposed as the best material model to represent the non-linear behavior of hydrogels, was verified using finite element (FE) simulations. The results revealed that the Young's modulus and maximum stress of hydrogels are increased by the addition of Gel. The highest Young's modulus (81 kPa) and maximum stress (24 kPa) were observed for hydrogels with 15 wt% Gel. Results also showed that the hydrogels with a relatively lower content (7.5 wt%) for skin tissue engineering. The Yeoh material model was closely fitted with the experimental data and could be used in further biomechanical simulations of the hydrogels. The experimental results were also compared well with those predicted by the FE models. The results of this study might have implications not only for the understanding of the mechanical properties of Gel hydrogel but also for the fabrication of polymeric substrate materials suitable for skin tissue engineering applications. PMID:24988278

Karimi, Alireza; Navidbakhsh, Mahdi

2014-12-01

19

Thermo-mechanical cementation effects in bentonite investigated by unconfined compression tests  

Energy Technology Data Exchange (ETDEWEB)

Results from the project LOT showed that specimens exposed to warm conditions had a significantly reduced strain at failure compared to reference material. The objective of the present study was to investigate the impact of parameters such as temperature, density, water content and degree of saturation on the occurrence of brittleness at failure of bentonite specimens. To quantify the influence of the different parameters the unconfined compression test was used on specimens with a height and diameter of 20 mm. In this test the relation between stress and strain is determined from axial compression of a cylindrical specimen. Brittle failure is in this investigation mainly seen on specimens having a density of rho >= 2,060 kg/m3 or on specimens exposed to high temperature T >= 150 deg C in the laboratory. Brittle failure behaviour was also seen on unsaturated specimens with a degree of saturation less than Sr < 90%. Failure at reduced strain was seen in this investigation on specimens exposed to T = 150 deg C, on specimens having a water content of w{sub i} = 0% before saturation, on specimens with a final degree of saturation of S{sub r} <= 97% and also on one specimen subjected to consolidation during preparation. Brittle failure and reduced strain were noticed in the heated field exposed material in the LOT project. Similar behaviour was also observed in the present short term laboratory tests. However, the specimens in the present study showing this behaviour had higher density, lower degree of saturation or were exposed to higher temperatures than the field exposed specimens

Dueck, Ann (Clay Technology AB, Lund (Sweden))

2010-01-15

20

Saturated-Unsaturated flow in a Compressible Leaky-unconfined Aquifer  

CERN Document Server

An analytical solution is developed for three-dimensional flow towards a partially penetrating large-diameter well in an unconfined aquifer bounded below by an aquitard of finite or semi-infinite extent. The analytical solution is derived using Laplace and Hankel transforms, then inverted numerically. Existing solutions for flow in leaky unconfined aquifers neglect the unsaturated zone following an assumption of instantaneous drainage assumption due to Neuman [1972]. We extend the theory of leakage in unconfined aquifers by (1) including water flow and storage in the unsaturated zone above the water table, and (2) allowing the finite-diameter pumping well to partially penetrate the aquifer. The investigation of model-predicted results shows that leakage from an underlying aquitard leads to significant departure from the unconfined solution without leakage. The investigation of dimensionless time-drawdown relationships shows that the aquitard drawdown also depends on unsaturated zone properties and the pumping...

Mishra, Phoolendra K; Kuhlman, Kristopher L

2011-01-01

 
 
 
 
21

Compressive Strength of Fibre Reinforced Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The thesis features an analysis of the time development of compressive strength of fibre reinforced normal and high strength concrete. Concrete mixtures, taken from the doctoral dissertation of assistant Dr Drago Saje, were used as comparable mixtures to fibre reinforced concrete mixtures with different volume shares of fibres. Two types of steel fibres were used, both featuring the same characteristics but having different lengths (16 and 30 mm), as well as polypropylene fibres. The percenta...

Jelus?ic?, Matjaz?

2009-01-01

22

(Finite) statistical size effects on compressive strength.  

Science.gov (United States)

The larger structures are, the lower their mechanical strength. Already discussed by Leonardo da Vinci and Edmé Mariotte several centuries ago, size effects on strength remain of crucial importance in modern engineering for the elaboration of safety regulations in structural design or the extrapolation of laboratory results to geophysical field scales. Under tensile loading, statistical size effects are traditionally modeled with a weakest-link approach. One of its prominent results is a prediction of vanishing strength at large scales that can be quantified in the framework of extreme value statistics. Despite a frequent use outside its range of validity, this approach remains the dominant tool in the field of statistical size effects. Here we focus on compressive failure, which concerns a wide range of geophysical and geotechnical situations. We show on historical and recent experimental data that weakest-link predictions are not obeyed. In particular, the mechanical strength saturates at a nonzero value toward large scales. Accounting explicitly for the elastic interactions between defects during the damage process, we build a formal analogy of compressive failure with the depinning transition of an elastic manifold. This critical transition interpretation naturally entails finite-size scaling laws for the mean strength and its associated variability. Theoretical predictions are in remarkable agreement with measurements reported for various materials such as rocks, ice, coal, or concrete. This formalism, which can also be extended to the flowing instability of granular media under multiaxial compression, has important practical consequences for future design rules. PMID:24733930

Weiss, Jérôme; Girard, Lucas; Gimbert, Florent; Amitrano, David; Vandembroucq, Damien

2014-04-29

23

Temperature dependence of uniaxial compressive strength of Hnilec granite  

Directory of Open Access Journals (Sweden)

Full Text Available Paper presents the results of the temperature dependence of uniaxial compressive strength of Hnilec Granite. The measurements of the uniaxial compressive strength were carried out at five different temperatures.

Laba? Milan

1997-09-01

24

Temperature dependence of uniaxial compressive strength of Hnilec granite  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Paper presents the results of the temperature dependence of uniaxial compressive strength of Hnilec Granite. The measurements of the uniaxial compressive strength were carried out at five different temperatures.

Laba? Milan

1997-01-01

25

Predicting mechanical properties of enhanced performance concrete using compressive strength  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mechanical properties of concrete are usually evaluated from compressive strength test results. Extensive literature, codes and regulations recommend the prediction of mechanical properties such as splitting and flexural tensile strength using the compressive strength of cylindrical specimens. These expressions are not related with the type of concrete and, generally, are only a function of the cylindrical compressive strength. It is the objective of this research work to in...

Camo?es, Aires; Aguiar, J. L. Barroso; Jalali, Said

2004-01-01

26

Compressive strength of delaminated aerospace composites.  

Science.gov (United States)

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. PMID:22431756

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

2012-04-28

27

Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions  

Directory of Open Access Journals (Sweden)

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.

Othuman Mydin M.A.

2014-01-01

28

STRENGTH SHRINKAGE AND CREEP OF CONCRETE IN TENSION AND COMPRESSION  

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Strength, shrinkage and creep of concrete in tension and compression have been determined and the relationship between those properties was studied. Direct tensile tests were applied to measure those properties in tension. The relationship of creep in tension and compression was determined based on the measurement of creep at similar stress and similar stress/strength ratio. It is found that concrete deforms more in tension than in compression. Except for concrete with a higher water/cement r...

Kristiawan, S. A.

2006-01-01

29

PHYSICAL BEHAVIOUR OF FOAMED CONCRETE UNDER UNI-AXIAL COMPRESSIVE LOAD: CONFINED COMPRESSIVE TEST  

Directory of Open Access Journals (Sweden)

Full Text Available Foamed concrete now is a common material used in civil engineering work. There are increasing amount in research where foamed concrete are used primarily to resist compression force. In this research, physical behaviour of foamed concrete was investigated. Based on the past research, the compressive strength of foamed concrete typically proportioned to achieve only low compressive strength in unconfined condition. Standard compressive test were performed to obtain the compressive strength of foamed concrete. In this research, the confined condition is produced. Unconfined condition also was done, but here just focused on confined condition. The confined compressive test method consist of applying a compressive axial load to moulded cylinders at a rate which is within a prescribe range until failure occurs. The physical behaviour of foamed concrete under confined condition is the continuity of unconfined condition and will be the guidance to conduct the further researchKeywords: foamed concrete, confined compressive test, mode of failure

Ahmad Mujahid Ahmad Zaidi

2010-01-01

30

STRENGTH SHRINKAGE AND CREEP OF CONCRETE IN TENSION AND COMPRESSION  

Directory of Open Access Journals (Sweden)

Full Text Available Strength, shrinkage and creep of concrete in tension and compression have been determined and the relationship between those properties was studied. Direct tensile tests were applied to measure those properties in tension. The relationship of creep in tension and compression was determined based on the measurement of creep at similar stress and similar stress/strength ratio. It is found that concrete deforms more in tension than in compression. Except for concrete with a higher water/cement ratio, the use of pulverised fuel ash, ground granulated blast furnace slag, superplasticizer and shrinkage reducing admixture has no effect on strength. However, they affect creep and shrinkage of concrete.

S A Kristiawan

2006-01-01

31

Compressive strength of brick masonry made with weak mortars  

DEFF Research Database (Denmark)

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<1N/mm2) in which the strength 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, which is the most unfavourable stress distribution with respect to tensile stresses in bricks. The expressionis compared with the results of compression tests of masonry made with weak mortars. It can take into account bricks with arbitrary dimensions as well as perforated bricks. For a stronger mortar (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. An extended version of the EC6 expression for the compressive strength of masonry is proposed, which includes the effect in question.

Pedersen, Erik Steen; Hansen, Klavs Feilberg

2013-01-01

32

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2013-01-01

33

Comparison Of Compressive Strength Of Medium Strength Self Compacted Concrete By Different Curing Techniques  

Directory of Open Access Journals (Sweden)

Full Text Available : In this paper variation in compressive strength of medium strength, self-compacted concrete with 3 different curing techniques is discussed. Initially several trials were carried out for mix design of medium strength selfcompacting concrete. Once the mix design was achieved, three batches of concrete cubes were cast as per ASTM standard. Water cement ratio and admixture dose were kept constant as required by selected Mix Design. Slump Test was carried out on each batch in order to ascertain concrete flow for self-compacting concrete. First batch was cured in a temperature controlled curing tank in the laboratory. The second batch was cured by the application of an external curing compound under prevailing site conditions. The 3rd batch was cured with internal curing agent. From each batch, 3 cubes were tested for compressive strength at 3-days age, at 7 days age and 28 days age of concrete and average values were taken. Results were analyzed and graphs were drawn.It was noted that 28-days compressive strength of cubes cured by applying curing compound was 91 % of the compressive strength of cubes cured in water tank in the laboratory (i.e., 09 % less.Similarly compressive strength of cubes cured by Internal curing compound was 95 % of the compressive strength of cubes cured in the laboratory (i.e., 05% less. So it was concluded that in areas with shortage of water, curing compounds can be effectively used with improved strength and sustainability of selfcompacted concrete

Prof. Nanak J Pamnani1, Dr. A.K. Verma2, Dr. D.R. Bhatt

2013-05-01

34

Comparison of Open-Hole Compression Strength and Compression After Impact Strength on Carbon Fiber/Epoxy Laminates for the Ares I Composite Interstage  

Science.gov (United States)

Notched (open hole) composite laminates were tested in compression. The effect on strength of various sizes of through holes was examined. Results were compared to the average stress criterion model. Additionally, laminated sandwich structures were damaged from low-velocity impact with various impact energy levels and different impactor geometries. The compression strength relative to damage size was compared to the notched compression result strength. Open-hole compression strength was found to provide a reasonable bound on compression after impact.

Hodge, Andrew J.; Nettles, Alan T.; Jackson, Justin R.

2011-01-01

35

Static strength of gold compressed up to 127 GPa  

International Nuclear Information System (INIS)

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

36

(Finite) statistical size effects on compressive strength  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The larger structures are, the lower their mechanical strength. Already discussed by Leonardo da Vinci and Edmé Mariotte several centuries ago, size effects on strength remain of crucial importance in modern engineering for the elaboration of safety regulations in structural design or the extrapolation of laboratory results to geophysical field scales. Under tensile loading, statistical size effects are traditionally modeled with a weakest-link approach. One of its prominent results is a pre...

Weiss, Je?ro?me; Girard, Lucas; Gimbert, Florent; Amitrano, David; Vandembroucq, Damien

2014-01-01

37

Effect of Hand Mixing on the Compressive Strength of Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the effect of hand mixing on the compressive strength of concrete. Before designing the concrete mix, sieve analysis of sharp sand and chippings was carried out and their fineness moduli were determined. Also the dry weight of chippings and the specific gravities of both sand and chippings were determined. A designed concrete mix of 1:2:4 was used and the number of turnings of the mixture over from one end to another by hand mixing was varying from one time up to and including seven times. The strengths were measured at the curing ages of 7, 14, 21 and 28 days respectively using 150mm concrete cubes cast, cured and crushed. The results revealed that the compressive strengths of concrete cubes appreciably increased with increase in number of turnings from one to four times but remained almost constant beyond four times of turning for all the ages tested. For example, at 1, 2, and 3 times turning; the compressive strengths at 28 days were 4.67, 13.37 and 20.28N/mm2 respectively while at 4, 5 and 6 times turning; the compressive strengths at 28 days were 21.15, 21.34 and 21.69N/mm2. From the data, adequate strengths were not developed at turnings below three times of hand mixing, concluding that a minimum of three times turning is required to produce concrete with satisfactory strength.

James Isiwu AGUWA

2010-12-01

38

Compressive Strength of Longitudinally Stiffened GRP Panels  

DEFF Research Database (Denmark)

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 identical failure scenario. In the present case, the load carring capacity of the stiffened panel is limited by the plate buckling capability.

Böhme, J.; Noury, P.

1996-01-01

39

Compressive strength of concrete and mortar containing fly ash  

Science.gov (United States)

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specifications required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs. 33 figs.

Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

1997-04-29

40

Compressive strength of concrete and mortar containing fly ash  

Science.gov (United States)

The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention includes a method for predicting the compressive strength of such a hardenable mixture, which is very important for planning a project. The invention also relates to hardenable mixtures comprising cement and fly ash which can achieve greater compressive strength than hardenable mixtures containing only concrete over the time period relevant for construction. In a specific embodiment, a formula is provided that accurately predicts compressive strength of concrete containing fly ash out to 180 days. In other specific examples, concrete and mortar containing about 15% to 25% fly ash as a replacement for cement, which are capable of meeting design specification required for building and highway construction, are provided. Such materials can thus significantly reduce construction costs.

Liskowitz, John W. (Belle Mead, NJ); Wecharatana, Methi (Parsippany, NJ); Jaturapitakkul, Chai (Bangkok, TH); Cerkanowicz, deceased, Anthony E. (late of Livingston, NJ)

1998-01-01

 
 
 
 
41

Effect Of Salt Water On Compressive Strength Of Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available In this research work, the effect of salt water on the compressive strength of concrete was investigated. This paper therefore presents the result and findings of an experimental research on the effect of salt water on compressive strength of concrete. For this concrete cubes were cast using fresh wi and salt water for a design mix of M-30 1:1.8:3.31 by weight of concrete, and 0.45 water- cement ratio. Half of concrete cubes were cast and cured with fresh water and remaining half cubes were cast and cured with salt water. The concrete cubes were cured for 7,14 and 28 days respectively. The result of the average compressive strength of concrete obtained using fresh water ranges from 27.12 - 39.12N/mm2 and using salt water ranges from 28.45 – 41.34N/mm2

Preeti Tiwari

2014-04-01

42

COMPRESSIVE STRENGTH AND SORPTIVITY PROPERTIES OF PET FIBER REINFORCED CONCRETE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents experimental results of compressive strength and sorptivity for normal concrete and PET fiber reinforced concrete (PFRC). The PET fibers used in this study were obtained manually from waste mineral water bottles. Two grades, M20 and M30, of concrete and two fiber geometry of aspect ratios 35 and 50 with fiber volume fractions 0.0 to 3.0% were used in the experiments. Each specimen was tested after 28 days of curing. It was found that the compressive strength of PFRC increa...

Nibudey, R. N.; Nagarnaik, P. B.; Parbat, D. K.; Pande, A. M.

2014-01-01

43

Effect Of Salt Water On Compressive Strength Of Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this research work, the effect of salt water on the compressive strength of concrete was investigated. This paper therefore presents the result and findings of an experimental research on the effect of salt water on compressive strength of concrete. For this concrete cubes were cast using fresh wi and salt water for a design mix of M-30 1:1.8:3.31 by weight of concrete, and 0.45 water- cement ratio. Half of concrete cubes were cast and cured with fresh water and remaining ha...

Preeti Tiwari; Rajiv Chandak

2014-01-01

44

Relationship between the Compressive and Tensile Strength of Recycled Concrete  

International Nuclear Information System (INIS)

Concrete recycling consists of crushing the concrete provided by demolishing the old constructions, and of using the resulted small pieces as aggregates in the new concrete compositions. The resulted aggregates are called recycled aggregates and the new mix of concrete containing a percentage of recycled aggregates is called recycled concrete. Our previous researches have indicated the optimal percentages of recycled aggregates to be used for different cases of recycled concrete related to the original aggregates nature. All results have shown that the concrete compressive strength is significantly reduced when using recycled aggregates. In order to obtain realistic values of compressive strength, some tests have been carried out by adding water-reducer plasticizer and a specified additional quantity of cement. The results have shown that for a limited range of plasticizer percentage, and a fixed value of additional cement, the compressive strength has reached reasonable value. This paper treats of the effect of using recycled aggregates on the tensile strength of concrete, where concrete results from the special composition defined by our previous work. The aim is to determine the relationship between the compressive and tensile strength of recycled concrete. (author)

45

Goose`s eggshell strength at compressive loading  

Directory of Open Access Journals (Sweden)

Full Text Available The paper deals with the study of the goose eggs behaviour under compressive loading between two plates using testing device TIRATEST. The influences of the loading orientation as well as the effect of compressive velocity are studied. 226 eggs from Landes geese were chosen for the experiment. Eggs have been loaded between their poles and in the equator plane. Five different compressive velocities (0.0167, 0.167, 0.334, 1.67 and 5 mm.s-1 were used. The increase in rupture force with loading rate was observed for loading in all direction (along main axes. Dependence of the rupture force on loading rate was quantifies and described. The highest rupture force was obtained when the eggs were loaded along their axes of symmetry (X-axis. Compression in the equator plane (along the Z-axis required the least compressive force to break the eggshells. The eggshell strength was described by the rupture force, specific rupture deformation and by the absorbed energy. The rupture force is highly dependent on compression speeds. The dependence of the rupture force on the compression velocity can be described by a power function. The same is valid for the rate dependence of the energy absorbed by the egg up to the fracture. The rate sensitivity of the Goose's eggshells strength is significantly higher than that reported for the hen's eggs

Šárka Nedomová

2014-02-01

46

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 temperature curing both conduction and radiation heating methods were attempted. The results show that multiple linear regression model, which uses the conduction heating process, performs best.

T.R. Neelakantan

2013-04-01

47

Unfired clay bricks – moisture properties and compressive strength  

DEFF Research Database (Denmark)

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 strength are presented.

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

2002-01-01

48

Compressive strength and hydration processes of concrete with recycled aggregates  

International Nuclear Information System (INIS)

This paper deals with the correlation between the time evolution of the degree of hydration and the compressive strength of Recycled Aggregate Concrete (RAC) for different water to cement ratios and initial moisture conditions of the Recycled Concrete Aggregates (RCAs). Particularly, the influence of such moisture conditions is investigated by monitoring the hydration process and determining the compressive strength development of fully dry or fully saturated recycled aggregates in four RAC mixtures. Hydration processes are monitored via temperature measurements in hardening concrete samples and the time evolution of the degree of hydration is determined through a 1D hydration and heat flow model. The effect of the initial moisture condition of RCAs employed in the considered concrete mixtures clearly emerges from this study. In fact, a novel conceptual method is proposed to predict the compressive strength of RAC-systems, from the initial mixture parameters and the hardening conditions. -- Highlights: •The concrete industry is more and more concerned with sustainability issues. •The use of recycled aggregates is a promising solution to enhance sustainability. •Recycled aggregates affect both hydration processes and compressive strength. •A fundamental approach is proposed to unveil the influence of recycled aggregates. •Some experimental comparisons are presented to validate the proposed approach

49

Compressive strength and hydration processes of concrete with recycled aggregates  

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the correlation between the time evolution of the degree of hydration and the compressive strength of Recycled Aggregate Concrete (RAC) for different water to cement ratios and initial moisture conditions of the Recycled Concrete Aggregates (RCAs). Particularly, the influence of such moisture conditions is investigated by monitoring the hydration process and determining the compressive strength development of fully dry or fully saturated recycled aggregates in four RAC mixtures. Hydration processes are monitored via temperature measurements in hardening concrete samples and the time evolution of the degree of hydration is determined through a 1D hydration and heat flow model. The effect of the initial moisture condition of RCAs employed in the considered concrete mixtures clearly emerges from this study. In fact, a novel conceptual method is proposed to predict the compressive strength of RAC-systems, from the initial mixture parameters and the hardening conditions. -- Highlights: •The concrete industry is more and more concerned with sustainability issues. •The use of recycled aggregates is a promising solution to enhance sustainability. •Recycled aggregates affect both hydration processes and compressive strength. •A fundamental approach is proposed to unveil the influence of recycled aggregates. •Some experimental comparisons are presented to validate the proposed approach.

Koenders, Eduardus A.B., E-mail: e.a.b.koenders@coc.ufrj.br [COPPE-UFRJ, Rio de Janeiro (Brazil); Microlab, Delft University of Technology (Netherlands); Pepe, Marco, E-mail: mapepe@unisa.it [Dept. of Civil Engineering, University of Salerno (Italy); Martinelli, Enzo, E-mail: e.martinelli@unisa.it [Dept. of Civil Engineering, University of Salerno (Italy)

2014-02-15

50

Fracture Energy of High-Strength Concrete in Compression  

DEFF Research Database (Denmark)

Compression tests are usually carried out in load control. This implies the termination of the test at the peak point of the load-displacement curve, while the fracture under these conditions becomes unstable at the descending branch of the load displacement relation. However, the descending branch 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 method has been used to investigate the influence of boundary conditions, loading rate, size effects and the influence of the strength on the fracture energy of high-strength concrete over the range 70 MPa to 150 MPa, expressed in nominal values.

Dahl, H.; Brincker, Rune

1989-01-01

51

Insulation interlaminar shear strength testing with compression and irradiation  

International Nuclear Information System (INIS)

The Compact Ignition Tokamak (CIT) project identified the need for research and development for the insulation to be used in the toroidal field coils. The requirements included tolerance to a combination of high compression and shear and a high radiation dose. Samples of laminate-type sheet material were obtained from commercial vendors. The materials included various combinations of epoxy, polyimide, E-glass, S-glass, and T-glass. The T-glass was in the form of a three-dimensional weave. The first tests were with 50 x 25 x 1 mm samples. These materials were loaded in compression and then to failure in shear. At 345-MPa compression, the interlaminar shear strength was generally in the range of 110 to 140 MPa for the different materials. A smaller sample configuration was developed for irradiation testing. The data before irradiation were similar to those for the larger samples but approximately 10% lower. Limited fatigue testing was also performed by cycling the shear load. No reduction in shear strength was found after 50,000 cycles at 90% of the failure stress. Because of space limitations, only three materials were chosen for irradiation: two polyimide systems and one epoxy system. All used boron-free glass. The small shear/compression samples and some flexure specimens were irradiated to 4 x 109 and 2 x 1010 rad in the Advanced Technology Reactor at Idaho National Engineering Laboratory. A lead shield was used to ensure that the majority of the dose was from neutrons. The shear strength with compression before and after irradiation at the lower dose was determined. Flexure strength and the results from irradiation at the higher dose level will be available in the near future. 7 refs., 7 figs., 2 tabs

52

Prediction of Compressive Strength of Concrete using Artificial Neural Network  

Directory of Open Access Journals (Sweden)

Full Text Available Concrete cube strength determination tests are usually performed at three days to one year afterpouring the concrete. The waiting period required to perform such test may delay the construction progress,decision making and neglecting such test would limit the quality control checks in large constructionprojects. Therefore it becomes necessary that the rapid and reliable prediction of concrete strength isessential for pre-design or quality control of construction. It is possible to facilitate the modification of themix proportion if the concrete does not meet the required design stage, which may save time andconstruction costs. The early prediction of concrete strength is essential for estimating the desirable time forconcrete form removal, project scheduling, quality control and estimating delay if any. Artificial NeuralNetwork (ANN is used to predict the compressive strength of concrete. Standard back propagation andJordan–Elman algorithms are used to train the networks. Networks are trained and tested at various learningrate and momentum factor and after many trials these were kept constant for this study. Performance ofnetworks were checked with statistical error criteria of correlation coefficient, root mean squared error andmean absolute error. It is observed that artificial neural networks can predict compressive strength ofconcrete with 91 to 98 % accuracy.

Wankhade M W

2013-07-01

53

Residual Compressive Strength of Laterized Concrete Subjected to Elevated Temperatures  

Directory of Open Access Journals (Sweden)

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.

Robert M. Brooks

2010-05-01

54

Dynamic microbuckling model for compressive strength of polymeric composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Dynamic compressive strength of off-axis fiber composites in the form of fiber microbuckling was studied. Both fiber misalignments and material nonlinearity were taken into account in this study. A fiber microbuckling model derived using micromechanics based on the nonlinear behavior of the matrix was extended to include the strain rate effect. The critical microbuckling stress was found to be the same as that in Rosen's bifurcation analysis except that elastic shear modulus was replaced by t...

Tsai, Jia-lin

2001-01-01

55

Compressive Strength of a Longitudinally Stiffened FRP Panel  

DEFF Research Database (Denmark)

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 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.

Riber, Hans JØrgen; Jensen, JØrgen Juncher

1997-01-01

56

A Compressive Strength Criterion for Anisotropic Rock Materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper puts forward a general compressive strength criterion for anisotropic rock materials under multiaxial state of stress. The proposed criterion, is a generalization of the Von Mises yield criterion for ductile metals, which criterion has previously been used for brittle fracture as well, both being looked upon as limits of linear elastic behaviour. The proposed criterion takes into consideration the effects, on rock material failure under multiaxial stress state, of confining pressur...

Ashour, H. A.

1988-01-01

57

Estimating compressive strength of concrete by mortar testing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Concrete mix design laboratory tests which time consuming and entails considerable effort. This study presents a method of reducing mix design testing costs by testing mortar instead of concrete specimens. The experimental programme consisted of defining mortar mixes equivalent to concrete mixes, moulding specimens of both mortar and concrete mixes studied and finally evaluating the compressive strength of specimens cured at different curing time. Results obtained indicate that a goo...

Camo?es, Aires; Aguiar, J. L. Barroso; Jalali, Said

2005-01-01

58

Compressive strength and durability properties of ceramic wastes based concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents an experimental study on the properties and on the durability of concrete containing ceramic wastes. Several concrete mixes possessing a target mean compressive strength of 30 MPa were prepared with 20% cement replacement by ceramic powder (W/B = 0.6). A concrete mix with ceramic sand and granite aggregates were also prepared as well as a concrete mix with natural sand and coarse ceramic aggregates (W/B = 0.5). The mechanical and durability performance of ceramic ...

Torgal, Fernando Pacheco; Jalali, Said

2010-01-01

59

Compression Strength of Sulfur Concrete Subjected to Extreme Cold  

Science.gov (United States)

Sulfur concrete cubes were cycled between liquid nitrogen and room temperature to simulate extreme exposure conditions. Subsequent compression testing showed the strength of cycled samples to be roughly five times less than those non-cycled. Fracture surface examination showed de-bonding of the sulfur from the aggregate material in the cycled samples but not in those non-cycled. The large discrepancy found, between the samples is attributed to the relative thermal properties of the materials constituting the concrete.

Grugel, Richard N.

2008-01-01

60

Compressive Strength and Microstructure of Sugar Cane Bagasse Ash Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available This study presents the results of an experimental research study on the effectiveness of Sugar Cane Bagasse Ash (SCBA as a cement replacement material in concrete production. The ordinary Portland cement was replaced with 0, 5, 10, 15, 20, 25 and 30%, respectively bagasse ash, the effect of Sugar cane Bagasse Ash on workability, compressive strength and microstructure of Interfacial Transition Zone (ITZ of concrete was examined. The results showed that inclusion of Sugar cane Bagasse Ash in concrete up to 20% level significantly enhanced the compressive strength of concrete at all ages; the highest compressive strength was obtained at 5% SCBA replacement level. The ITZ thickness was greatly reduced with increasing the bagasse ash replacement level up to 15%, beyond that the ITZ thickness was slightly increased, however the thickness was still narrower than the normal concrete, it was observed that at 15% bagasse ash replacement level, the interfacial transition zone was homogeneous and there was no gap between the coarse aggregate and the paste matrix.

Asma Abd Elhameed Hussein

2014-03-01

 
 
 
 
61

COMPRESSIVE STRENGTH AND SORPTIVITY PROPERTIES OF PET FIBER REINFORCED CONCRETE  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents experimental results of compressive strength and sorptivity for normal concrete and PET fiber reinforced concrete (PFRC. The PET fibers used in this study were obtained manually from waste mineral water bottles. Two grades, M20 and M30, of concrete and two fiber geometry of aspect ratios 35 and 50 with fiber volume fractions 0.0 to 3.0% were used in the experiments. Each specimen was tested after 28 days of curing. It was found that the compressive strength of PFRC increased and the sorptivity of PFRC was decreased with respect to normal concrete. The optimum fiber volume fraction of PET fibers was found to be 1%. From the test results, mathematical models for predicting sorptivity of PFRC in terms of compressive strength and fiber volume fraction were established and which works within 90% confidence limit. The addition of PET fibers in concrete tends to restrict water propagation in the concrete and causes reduction in sorptivity. The decrease in sorptivity of PFRC is favorable to the durability of the reinforced cement concrete structures. The fibers used in the study were made up from waste plastics which help to reduce the cost FRC and resolve solid waste disposal problems also.

R. N. Nibudey

2014-09-01

62

Flow strength of tantalum under ramp compression to 250?GPa  

International Nuclear Information System (INIS)

A magnetic loading technique was used to study the strength of polycrystalline tantalum ramp compressed to peak stresses between 60 and 250?GPa. Velocimetry was used to monitor the planar ramp compression and release of various tantalum samples. A wave profile analysis was then employed to determine the pressure-dependence of the average shear stress upon unloading at strain rates on the order of 105?s?1. Experimental uncertainties were quantified using a Monte Carlo approach, where values of 5% in the estimated pressure and 9–17% in the shear stress were calculated. The measured deviatoric response was found to be in good agreement with existing lower pressure strength data as well as several strength models. Significant deviations between the experiments and models, however, were observed at higher pressures where shear stresses of up to 5?GPa were measured. Additionally, these data suggest a significant effect of the initial material processing on the high pressure strength. Heavily worked or sputtered samples were found to support up to a 30% higher shear stress upon release than an annealed material

63

Compressive strength and microstructural properties of lightweight high-strength cement mortar reinforced with eloxal  

International Nuclear Information System (INIS)

An investigation was carried out to evaluate the results of the compressive strength of high-strength lightweight eloxal reinforced cement mortar subject to short term loads. An experimental method similar to the one proposed by the author on chilled aluminum-quartz reinforced metal matrix composite was used. Eloxal (in the solid slag form) is a waste obtained during the production of aluminum in the plant. It is mainly of aluminum oxide, SiO2, CaO, MgO and other substances. It is a hard substance, having sufficient strength with additive properties and bonds very rapidly. Eloxal reinforced cement mortar in the present investigation are tested for its compressive and microstructural behavior. Data were obtained pertaining to compressive strength, role of moisture and drying effects. Deformation under compressive load were studied to provide insight into the internal behavior and failure mechanism of lightweight eloxal reinforced cement mortar. To analyze the mode of failure under compression, distribution of eloxal particles in cement mortar and the deformation behavior, several optical and scanning electron microscope photographs were taken to study the mechanism. Results of the tests of eloxal reinforced cement mortar are compared with unreinforced cement mortar and information obtained else where in earlier tests of normal weight cement mortar. Structural composite materials offer an excellent opportunity to produce components that achieve weight savingsuce components that achieve weight savings and improved properties. The eloxal particles (dispersoid) added to cement mortar in the present investigation is varied from 20 to 40 wt% in steps of 10 wt%. The resulting composite blocks cast were tested for their properties

64

INTRA-RING COMPRESSION STRENGTH OF LOW DENSITY HARDWOODS  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Engineered wood composites are being crafted with increasingly smaller and smaller components, yet a search of the literature indicates a lack of intra-ring mechanical property data for almost all commercial wood types, particularly the underutilized low density hardwoods. In addition, there is no u [...] niversally accepted testing regime for determining micromechanical properties of wood samples. As a result, we developed a testing system for determining compression, tension, and bending properties of growth ring regions of wood samples. Our microtesting system consists of a 45.4 kg load stage, motor drive, data acquisition system, motor control, load cell, strain transducer, and software. In this study, intra-ring compression strength parallel to the grain was determined for small samples (a few millimeters³ in volume) of sweetgum (Liquidambar styraciflua), yellow-poplar (Liriodendron tulipifera), and red maple (Acer rubrum). It was determined that compression strength is weakly correlated with specific gravity but unrelated to growth rate. Specific gravity was also unrelated to growth rate. Sweetgum values were intermediate between yellow-poplar and red maple

Audrey, Zink-Sharp; Carlile, Price.

65

Compressive strength test for cemented waste forms: validation process  

International Nuclear Information System (INIS)

In the Cementation Laboratory (LABCIM), of the Development Centre of the Nuclear Technology (CNEN/CDTN-MG), hazardous/radioactive wastes are incorporated in cement, to transform them into monolithic products, preventing or minimizing the contaminant release to the environment. The compressive strength test is important to evaluate the cemented product quality, in which it is determined the compression load necessary to rupture the cemented waste form. In LABCIM a specific procedure was developed to determine the compressive strength of cement waste forms based on the Brazilian Standard NBR 7215. The accreditation of this procedure is essential to assure reproductive and accurate results in the evaluation of these products. To achieve this goal the Laboratory personal implemented technical and administrative improvements in accordance with the NBR ISO/IEC 17025 standard 'General requirements for the competence of testing and calibration laboratories'. As the developed procedure was not a standard one the norm ISO/IEC 17025 requests its validation. There are some methodologies to do that. In this paper it is described the current status of the accreditation project, especially the validation process of the referred procedure and its results. (author)

66

Predicting compressive strength of different geopolymers by artificial neural networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the present study,six different models based on artificial neural networks have been developed to predict the compressive strength of different types of geopolymers.The differences between the models were in the number of neurons in hidden layers and in the method of finalizing the models.Seven independent input parameters that cover the curing time,Ca(OH)2 content, the amount of superplasticizer, NaOH concentration,mold type,geopolymer type and H2O/Na2O molar ratio were considered.For ...

Nazari, A.; Torgal, Fernando Pacheco

2013-01-01

67

Concrete aggregate and cement mass content effects on compressive strength  

Directory of Open Access Journals (Sweden)

Full Text Available The mass content of aggregate (ma and of cement (mc of concrete comprise coefficient calculated as ma/mc. Some methods used for designing of concrete mixtures take into consideration this coefficient. In this paper, concrete mixtures were prepared so that mass of cement, water cement factor and granulometric composition have been varied. Values of the coefficient ma/mc in experimental research ranged between 7,20 in concrete mixtures mixed with 250 kg of cement to 3,60 in concrete mixtures mixed with 500 kg per 1m3. From the aspect of compressive strength of concrete, it has been established that optimum values of the coefficient ma/mc depend on the granulometric composition and water cement factor. At higher water cement factors, larger values of ma/mc coefficient are required to achieve the maximum strength under the given conditions.

Grdi? Zoran

2010-01-01

68

Compressive strength and hydrolytic stability of fly ash based geopolymers  

Directory of Open Access Journals (Sweden)

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

Nikoli? Irena

2013-01-01

69

Strength and stiffness of thermally rectified eucalyptus wood under compression  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The aim of this work was the evaluation of the thermal-rectification process of reforestation wood Corymbia citriodora Hook by measuring of mechanical properties under compression parallel to the grain and also determining of chemical composition. The tested samples were thermally treated in a furna [...] ce with nitrogen-atmosphere at heating rate of 0.033 ºC.min-1, at temperatures of 160, 180, 200, 220 and 240 ºC. The chemical components and mechanical properties were affected with the thermal rectification process. The contents ranged from 17.85 to 3.51% extractives, 30.44 to 53.86% lignin, 69.56 to 46.14% holocellulose and 0.31 to 0.47% ashes. The samples strength decreased from 20% to 50% and the elasticity modulus increased about 47%. The characteristic values of strength under compression were determined and these changes were about 23% lower than Brazilian standard. The best mechanical properties of Corymbia citriodora were obtained at 180 ºC.

Marcio Rogério da, Silva; Gilmara de Oliveira, Machado; José Otávio, Brito; Carlito, Calil Junior.

1077-10-01

70

Correlation between Compressive Strength and Rheological Parameters of High-Performance Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available Compressive strength is greatly influenced by the performance of concrete in its fresh stage such as uniform mixing, proper compaction, resistance to segregation during transporting and placing. Attempt has, therefore, been made to correlate compressive strength to the rheological behavior of high performance concrete with a modified setup of parallel plate rheometer. Modified setup considers the shearing of concrete at the centre of the cylindrical container that takes into account the resistance between concrete and the vertical side of the wall. It has been observed that compressive strength increases steeply as the yield strength increases up to a certain level. Plastic viscosity, however, shows optimum value for maximum compressive strength.

Sudip Talukdar

2007-12-01

71

Permeability, porosity and compressive strength of self-compacting concrete  

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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 alcanzan mayores resistencias, si bien, cuando para su fabricación se emplean grandes cantidades de finos calizos cuyo equivalente de arena es bajo la tendencia se invierte, obteniéndose peores resultados. Por último, se ha establecido una relación de tipo lineal entre la profundidad de penetración de agua y la resistencia a compresión. Dicha relación depende a su vez del tipo de hormigón, dado que los hormigones autocompactables son menos permeables que los tradicionales para una misma resistencia.

Valcuende, M.O.

2005-12-01

72

Compressive strength and hardness of metal matrix syntactic foams  

International Nuclear Information System (INIS)

Six types of metal matrix syntactic foams (MMSFs) were produced by pressure infiltration technique. The foams were investigated by upsetting tests at increased (2200C) and at room (250C) temperature. The parameters were the constituents of the composites and the aspect ratio (height-diameter ratio, H/D) of the specimens. The characteristic properties were: the compressive strength, the fracture strain, the structural stiffness of the foams and the absorbed energy. The strength, the strain and the energy were decreased while the stiffness was increased by increasing the H/D. Increased temperature caused ?25 % drop in the strength and in the stiffness. Macrohardness, depth sensitive and dynamic hardness tests were also performed on MMSF blocks: macrohardness is a structural property and independent from the matrix material. The depth sensitive hardness is sensitive to the deformation capability of the matrix and to a possible change reaction. The dynamic hardnesses of the MMSFs were higher than the hardness of the matrices and this is a microballoon related property.

73

Effect of Cellulose-Ibeta Presence in Sawdust on Compressive Strength of Cement Paste  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, enhancement of compressive strength of OPC paste is main objective. 1% and 4% of sawdust powder has been blended to Ordinary Portland Cement (OPC paste. The compressive strength has been measured on 7, 28, 56 and 90 days. The micro properties of OPC paste has been investigated by using X-ray diffraction (XRD and Atomic Force Microscopy (AFM. The best quantity for replacement of sawdust is 1%. The mixture of 4% sawdust to OPC paste has also been improved compressive strength of concrete. The cellulose-Ibeta presences in saw dust, has been modified the surface roughness and hydration of OPC paste, and leads to enhancement of compressive strength of concrete. The compressive strength of OPC paste has been stabilized with increase of age, due to pozzolanic actions. The compressive strength of OPC has been decreased with increase sawdust contents.

Abdoullah Namdar

2014-02-01

74

Compressive strength after blast of sandwich composite materials.  

Science.gov (United States)

Composite sandwich materials have yet to be widely adopted in the construction of naval vessels despite their excellent strength-to-weight ratio and low radar return. One barrier to their wider use is our limited understanding of their performance when subjected to air blast. This paper focuses on this problem and specifically the strength remaining after damage caused during an explosion. Carbon-fibre-reinforced polymer (CFRP) composite skins on a styrene-acrylonitrile (SAN) polymer closed-cell foam core are the primary composite system evaluated. Glass-fibre-reinforced polymer (GFRP) composite skins were also included for comparison in a comparable sandwich configuration. Full-scale blast experiments were conducted, where 1.6×1.3?m sized panels were subjected to blast of a Hopkinson-Cranz scaled distance of 3.02?m?kg(-1/3), 100?kg TNT equivalent at a stand-off distance of 14?m. This explosive blast represents a surface blast threat, where the shockwave propagates in air towards the naval vessel. Hopkinson was the first to investigate the characteristics of this explosive air-blast pulse (Hopkinson 1948 Proc. R. Soc. Lond. A 89, 411-413 (doi:10.1098/rspa.1914.0008)). Further analysis is provided on the performance of the CFRP sandwich panel relative to the GFRP sandwich panel when subjected to blast loading through use of high-speed speckle strain mapping. After the blast events, the residual compressive load-bearing capacity is investigated experimentally, using appropriate loading conditions that an in-service vessel may have to sustain. Residual strength testing is well established for post-impact ballistic assessment, but there has been less research performed on the residual strength of sandwich composites after blast. PMID:24711494

Arora, H; Kelly, M; Worley, A; Del Linz, P; Fergusson, A; Hooper, P A; Dear, J P

2014-05-13

75

Strength of optical glass under conditions of axial compression  

Energy Technology Data Exchange (ETDEWEB)

The authors investigate the structural strength of different kinds of optical glass under axial compression, with examinations of the chemical composition, the shape of the cross section, and the conditions of support of the specimens, as well as the length of their storage after their protection. Optical glass types LK5, K8, TK3, TK114, belonging to the group of crown glasses, and F1, F101, TF101, TF10, belonging to the group of flint glasses, were studied. Tests of technical glass and pyrocerams show that destruction in the form of spalling of the bearing edges and cracking of the specimens due to longitudinal cracks begins long before the limit load is attained.

Okrimenko, G.M.; Maslov, V.P.; Rodichev, Y.M.

1986-04-01

76

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 sim...

Juan Manuel Lizarazo Marriaga; José Gabriel Gómez Cortés

2010-01-01

77

Experimental Study of Confined Low-, Medium- and High-Strength Concrete Subjected to Concentric Compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An experimental study of 23 low-, medium- and high-strength concrete columns is presented in this paper. Square-confined concrete columns without longitudinal reinforcement were designed, and tested under concentric axial compression. The columns were made of concrete with a compressive strength ranging between 30 MPa and 70 MPa. The test parameters in the study are concrete compressive strengths and confining steel properties, i.e. spacing, volumetric ratios and configurations. The effects o...

Antonius; Iswandi Imran

2012-01-01

78

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

DEFF Research Database (Denmark)

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 0.45) and addition of large amounts of SAP, this effect cannot counterbalance the strength reducing effect of increased void volume. In these cases, SAP addition reduces the compressive strength.

Hasholt, Marianne Tange; Jespersen, Morten H. Seneka

2010-01-01

79

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

Directory of Open Access Journals (Sweden)

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.

Juan Manuel Lizarazo Marriaga

2010-04-01

80

Diametral Compressive Strength and Elastic Modulus of Flattened Disc using Diametral Compressive Test  

International Nuclear Information System (INIS)

The nuclear grade graphite is the candidate materials for the in-core components of the very high temperature gas-cooled tractor (VHTR) due to its very high conductivity, melting temperature, chemical resistance and mechanical stability. Nuclear graphite undergoes dimensional change and mechanical properties change because of irradiation damage. To estimate the irradiation damage, surveillance capsule would be inserted in reactor. Surveillance capsule sizes were limited because it would be located inside of a reactor vessel. Thus, a new test method using small specimen is needed and diametral compressive test is one of them. However, circular anvils are needed according to the specimen size. A flattened disc specimen were proposed to overcome such a problem and applied for determination of mechanical properties for brittle rocks. In this study, the applicability of such specimen was investigated. In addition, minimum specimen size for test was determined and diametral compressive strength of nuclear graphite was measured

 
 
 
 
81

Numerical analysis of the spacer grids' compression strength  

International Nuclear Information System (INIS)

Among the components of the fuel assembly, the spacer grids play an important structural role during the energy generation process, mainly for their requirement to have enough structural strength to withstand lateral impact loads, due to fuel assembly shipping/handling and due to forces outcome from postulated accidents (earthquake and LOCA). This requirement ensures a proper geometry for cooling and for guide thimble straightness in the fuel assembly. In this way, the understanding of the macroscopic mechanical behavior of this component becomes essential even to any subsequent geometrical modifications to optimize the flue assemblies' structural behavior. In the present work, three-dimensional finite element models destined to provide consistent predictions of 16X16-type spacer grids lateral strength were proposed. Firstly, buckling tests based on results available in the literature were performed to establish a methodology for spacer grid finite element-based modeling. The, by considering a spacer grid interesting geometry and some possible variations associated to its fabrication, tolerance, the proposed numerical models were submitted to compression conditions to calculate the buckling force. Also, these models were validated for comparison with experimental buckling load results. Comparison of buckling predictions combined to observations of actual and simulated deformed spacer grids geometries permitted to verify the consistency and applicability of the proposed models. Thus, these numerical results show a good agreement between the and the experimental results. (author)

82

Effect of Specimen Size on Compressive, Modulus of Rupture and Splitting Strength of Cement Mortar  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It is well known that the strength of any tested matrix materials like concrete or mortar is affected by the specimen size; therefore it is important to consider the effect of specimen size when estimating the ultimate strength of such materials. This study presents the effect of specimen size on the mechanical properties of cement mortar. These include the compressive, splitting strength and modulus of rupture. For the compressive strength three different sizes of cylinder and three sizes of...

Majeed, Sura A.

2011-01-01

83

Influence of Cementitious Materials and Aggregates Content on Compressive Strength of Palm Kernel Shell Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available This study reports the effect of cementitious materials, fine and coarse aggregates content on workability and compressive strength of palm kernel shell concrete. Palm kernel shells a by product of the production of palm oil, were used as lightweight aggregates. The following cementitious materials were added: 10% silica fume as additional cementitious material and 5% fly ash as cement replacement on weight of cement. The influence of varying fine aggregate and palm kernel shell contents on workability and compressive strength has been studied. The specimens have been cured under three different curing environments to study the effect on compressive strength. The effect of cementitious materials and curing conditions on compressive strength for a period of 90 days was analyzed. The fresh density of concrete was found to be in the range of 1810 to 1940 kg m-3. The strength of Palm Kernel Shells (PKS was found to be the primary factor controlling the strength. However, the addition of silica fume was found to have influence on compressive strength. An increase in fine aggregate content and subsequent decrease in PKS content had positive effect on both workability and compressive strength. The 28 day compressive strengths of the mixes containing cementitious materials were found in the range of 26 to 36 MPa. The difference in strength between water cured and specimens cured under controlled environment was found to vary between 3 and 5%.

U.J. Alengaram

2008-01-01

84

Effect of size and shape of specimen on compressive strength of glass fiber reinforced concrete (GFRC  

Directory of Open Access Journals (Sweden)

Full Text Available Concrete is a versatile material with tremendous applications in civil engineering construction. Structural concrete elements are generally made with concrete having a compressive strength of 20 to 35 MPa. Lately, there is an increase in use of high strength concrete (HSC in major construction projects such as high-rise buildings, and bridges involving members of different sizes and shapes. The compressive strength of concrete is used as the most basic and important material property in the design of reinforced concrete structures. It has become a problem to use this value as the control specimen sizes and shapes are different from country to country. In India, the characteristic compressive strength is usually measured based on 150 mm cubes [1]. But, the ACI code of practice specifies the design compressive strength based on the standard 150x300 mm cylinders [2]. The use of 100x200 mm cylinders gained more acceptance as the need to test high strength concrete increases [3]. In this context the size and shape of concrete becomes an important parameter for the compressive strength. In view of the significance of compressive strength of concrete and due to the fact that the structural elements of different sizes and shapes are used, it is proposed to investigate the effect of size and shape of the specimen on the compressive strength of concrete. In this work, specimens of plain as well as Glass Fiber Reinforced Concrete (GFRC specimens are cast in order to carry out a comparative study.

Krishna Rao M.V.

2011-01-01

85

Estimate of Compressive Strength for Concrete using Ultrasonics by Multiple Regression Analysis Method  

International Nuclear Information System (INIS)

Various types of ultrasonic techniques have been used for the estimation of compressive strength of concrete structures. However, conventional ultrasonic velocity method using only longitudial wave cannot be determined the compressive strength of concrete structures with accuracy. In this paper, by using the introduction of multiple parameter, e. g. velocity of shear wave, velocity of longitudinal wave, attenuation coefficient of shear wave, attenuation coefficient of longitudinal wave, combination condition, age and preservation method, multiple regression analysis method was applied to the determination of compressive strength of concrete structures. The experimental results show that velocity of shear wave can be estimated compressive strength of concrete with more accuracy compared with the velocity of longitudinal wave, accuracy of estimated error range of compressive strength of concrete structures can be enhanced within the range of ± 10% approximately

86

Compressive strength, microstructure and hydration products of hybrid alkaline cements  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Ordinary Portland cement (OPC) is the dominant binder in the construction industry with a global production that currently reaches a total of 3 Gt per year. As a consequence, the cement industry's contribution to the total worldwide CO2 emissions is of about 7% of the total emissions. Publications o [...] n the field of alkali-activated binders (also termed geopolymers), state that this new material is, potentially, likely to fbecome an alternative to Portland cement. However, recent LCA studies show that the environmental performance of alkali-activated binders depends, to great extent, of their composition. Also, researchers report that these binders can be produced in a more eco-efficient manner if the use of sodium silicate is avoided. This is due to the fact that the referred component is associated to a high carbon footprint. Besides, most alkali-activated cements suffer from severe efflorescence, a reaction originated by the fact that the alkaline and/or soluble silicates that are added during processing cannot be totally consumed. This paper presents experimental results on hybrid alkaline cements. The compressive strength results and the efflorescence observations show that some of the new mixes already exhibit a promising performance.

Zahra, Abdollahnejad; Petr, Hlavacek; Sergio, Miraldo; Fernando, Pacheco-Torgal; José Luís Barroso de, Aguiar.

87

Dependence of compressive strength of green compacts on pressure, density and contact area of powder particles  

International Nuclear Information System (INIS)

The relationship between green compressive strength and compacting pressure as well as green density has been investigated for uniaxially pressed aluminium powder compacts in the range 0 - 520 MPa. Two linear relationships occurred between compacting pressure and green compressive strength which corresponded to powder compaction stages II and III respectively, increase in strength being large during stage II and quite small in stage III with increasing pressure. On the basis of both, the experimental results and a previous model on cold compaction of powder particles, relationships between green compressive strength and green density and interparticle contact area of the compacts has been established. (author) 9 figs

88

The estimation of compressive strength of normal and recycled aggregate concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Jankovi? Ksenija; Nikoli? Dragan; Bojovi? Dragan; Lon?ar Ljiljana; Romakov Zoran

2011-01-01

89

Multiple Regression Model for Compressive Strength Prediction of High Performance Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A mathematical model for the prediction of compressive strength of high performance concrete was performed using statistical analysis for the concrete data obtained from experimental work done in this study. The multiple non-linear regression model yielded excellent correlation coefficient for the prediction of compressive strength at different ages (3, 7, 14, 28 and 91 days). The coefficient of correlation was 99.99% for each strength (at each age). Also, the model gives high correlat...

Zain, M. F. M.; Abd, S. M.

2009-01-01

90

Developing a forecasting model of concrete compressive strength using relevance vector machines  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We analyze results of two experiments that tested effect of adding Silica on the compressive strength of concrete at early stage and after long period. The two experiments evaluated different silica/cement ratios for different mixing periods. Adding Silica to concrete mix produce high early strength material which is highly desirable in airports and highways. More than 90 samples of different silica/cement ratios are tested for compressive strength at 3 and 28 days. Test results sho...

Mohammad Awwad

2014-01-01

91

Influence of Plastic Waste Fibers on the Strength of Lime-Rice Husk Ash Stabilized Clay Soil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A study has been undertaken to investigate the strength of stabilized clay-soil reinforced with randomly distributed discrete plastic waste fibers by carrying out unconfined compressive strength and tensile-split strength test. In this study, the clay soil was stabilized with lime and rice husk ash mixtures. The effect of the fiber length and content on the compressive and split tensile strength was investigated. The laboratory investigation results show that inclusion of the plastic waste fi...

Muntohar, A. S.

2009-01-01

92

Compression specific toughness of normal strength steel fiber reinforced concrete (NSSFRC and high strength steel fiber reinforced concrete (HSSFRC  

Directory of Open Access Journals (Sweden)

Full Text Available Compression toughness tests were carried out on concrete cylinders reinforced with three different aspect ratios of hooked-end steel fibers 60, 75, and 83 and six different percentages of steel fibers 0.5, 1.0, 1.25, 1.5, 1.75, and 2.0% by volume of concrete. The w/c ratio used for the normal strength steel fiber reinforced concrete mixes (NSSFRC was 0.55, and the water-cementitious ratio (w/c+s for the high strength fiber reinforced concrete mixes (HSSFRC was 0.31. For each mix, three test cylinders were tested for compression specific toughness. The effect of fiber reinforcement index: volume of fibers × length/diameter ratio on compression specific toughness and also on the relationship between these two properties is presented in this paper. As a result, (a equations are proposed to quantify the effect of fibers on compression toughness ratio of concrete in terms of FRI, (b equations obtained in terms of FRI and compression specific toughness of plain concrete to estimate both compression specific toughness of NSSFRC and HSSFRC (N.m, (c equations obtained which represent the relationship between compression toughness index and FRI for NSSFRC and HSSFRC, respectively, and (d equations obtained to quantify the relationship between compression specific toughness index and fiber reinforcement index for NSSFRC and HSSFRC, respectively. The proposed equations give good correlation with the experimental values.

Khaled Marara

2011-01-01

93

Experimental studies on quantitative CT prediction of compressive strength of thoracolumbar vertebral bodies  

International Nuclear Information System (INIS)

Testing 98 motion segments we investigated the possibility of a prediction of the compressive strength of thoraco-lumbar vertebrae by QCT. The ultimate compressive strength can be predicted from the density of the trabecular bone and from the size of the endplates - both determined by QCT - with an error of 1 kN. The increase of compressive strength in cranio - caudal direction is calculated at approximately 0.3 kN per anatomical level. This variation is due to the increase of the endplate areas. (orig.)

94

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

Directory of Open Access Journals (Sweden)

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.

Sudin M.A.S.

2014-03-01

95

Correction factors to predict the in-place compressive strength of a self-compacting concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present study aimed to determine whether certain correction factors used in the in-place prediction of compressive strength with concrete cores are directly applicable to self-consolidating concretes (SCCs). The parameters considered were core diameter, casting direction, core moisture, a number of variables intrinsic to cores, and concrete strength. Factors were also established for converting SCC 15 3 15-cm cubic specimen strength into 30 315-cm cylindrical specimen strength. Th...

Rojas-henao, L.; Ferna?ndez-go?mez, J.; Lo?pez-agu?i, J. C.

2013-01-01

96

Influence of added concrete compressive strength on adhesion to an existing concrete substrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An experimental study was performed to evaluate the bond strength between two concrete layers of different ages, considering different mixtures of added concrete, with different strengths. The specimens first had the roughness of the substrate surface increased by sand blasting. Later, the new concrete was added. Afterwards, slant shear tests were performed to quantify the bond strength in shear. These tests indicated that increasing the compressive strength of the added concrete relative to ...

Ju?lio, Eduardo N. B. S.; Branco, Fernando A. B.; Silva, Vi?tor D.; Lourenc?o, Jorge F.

2006-01-01

97

Tension/compression asymmetry in yield and creep strengths of ni-based superalloys  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The tension/compression asymmetries of yield and creep strengths of three kinds of single-crystal superalloys-PWA1480, CMSX-4, and TMS-75 - and a DS superalloy, Mar-M247LC, were investigated at intermediate and high temperatures. In PWA1480, tensile yield strength was higher than the compressive strength from 20°C to 750°C From the TEM observation, it was found that the asymmetry of yield strengths is primarily due to the microtwin formation associated with a superlattice extrinsic stacking...

Tsuno, N.; Shimabayashi, S.; Kakehi, K.; Rae, Cmf; Reed, Rc

2008-01-01

98

Multiple Regression Model for Compressive Strength Prediction of High Performance Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available A mathematical model for the prediction of compressive strength of high performance concrete was performed using statistical analysis for the concrete data obtained from experimental work done in this study. The multiple non-linear regression model yielded excellent correlation coefficient for the prediction of compressive strength at different ages (3, 7, 14, 28 and 91 days. The coefficient of correlation was 99.99% for each strength (at each age. Also, the model gives high correlation for strength prediction of concrete with different types of curing.

M. F.M. Zain

2009-01-01

99

FACTORS INFLUENCING THE COMPRESSIVE STRENGTH OF FLY ASH-BASED GEOPOLYMER CONCRETE  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the effects of several factors on the properties of fly ash based geopolymer concrete, especially the compressive strength. The test variables included were the age of concrete, curing time, curing temperature, quantity of superplasticizer, the rest period prior to curing, and the water content of the mix. The test results show that the compressive strength of geopolymer concrete does not vary with age, and curing the concrete specimens at higher temperature and longer curing period will result in higher compressive strength. Furthermore, the commercially available Naphthalene-based superplasticizer improves the workability of fresh geopolymer concrete. The start of curing of geopolymer concrete at elevated temperatures can be delayed at least up to 60 minutes without significant effect on the compressive strength. The test data also show that the water content in the concrete mix plays an important role.

Djwantoro Hardjito

2004-01-01

100

Compressive strength, chloride permeability, and freeze-thaw resistance of MWNT concretes under different chemical treatments.  

Science.gov (United States)

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. PMID:25140336

Wang, Xingang; Rhee, Inkyu; Wang, Yao; Xi, Yunping

2014-01-01

 
 
 
 
101

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 prepar...

Ortega A?lvarez, Jose? Marcos; Pastor Navarro, Jose? Luis; Albaladejo Ruiz, Arturo; Sa?nchez Marti?n, Isidro; Climent Llorca, Miguel A?ngel

2014-01-01

102

Face compression yield strength of the copper-Inconel composite specimen  

International Nuclear Information System (INIS)

A new equation for the face compression yield strength of copper-Inconel composite material has been derived. Elastic-plastic finite element analyses were also made for composite specimens with various aspect ratios to examine the edge effect of the specimen. According to the results of both the new equation and the analyses, the face compression yield strength of the composite should be decreased by about 25% from the value obtained with Becker's equation

103

Prediction of compressive strength of concrete containing fly ash using data mining techniques  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The concrete compressive strength is the most used mechanical property in the design of concrete structures. Therefore, the use of rational models to its prediction, to simulate the effects of its different constituents and its properties can play an important role in the achievement of the safety-economy required. Models to forecast the concrete compressive strength have already been presented before by some researchers. However, the comparison of different rational models and the applicatio...

Martins, Francisco F.; Camo?es, Aires

2013-01-01

104

Compression Strength of Fir and Beech Wood Modified by Citric Acid  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Previous articles have shown that modification of wood by citric acid (CA) improves dimensional stability and resistance of wood against fungi attack. However, chemical modification of wood also modifies its mechanical properties in some way. The compression strength of wood is one of its representative mechanical properties. Modified wood with lower values of compression strength has limited purpose. The intention of this work is to show the effect of wood modification by citric acid on the ...

Bogoslav Šefc; Jelena Trajkovi?; Tomislav Sinkovi?; Marin Hasan; Iva Ištok

2012-01-01

105

FACTORS INFLUENCING THE COMPRESSIVE STRENGTH OF FLY ASH-BASED GEOPOLYMER CONCRETE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper describes the effects of several factors on the properties of fly ash based geopolymer concrete, especially the compressive strength. The test variables included were the age of concrete, curing time, curing temperature, quantity of superplasticizer, the rest period prior to curing, and the water content of the mix. The test results show that the compressive strength of geopolymer concrete does not vary with age, and curing the concrete specimens at higher temperature and longer cu...

Djwantoro Hardjito; Wallah, Steenie E.; Sumajouw, Dody M. J.; Rangan, B. V.

2004-01-01

106

Correlation between Compressive Strength and Rheological Parameters of High-Performance Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Compressive strength is greatly influenced by the performance of concrete in its fresh stage such as uniform mixing, proper compaction, resistance to segregation during transporting and placing. Attempt has, therefore, been made to correlate compressive strength to the rheological behavior of high performance concrete with a modified setup of parallel plate rheometer. Modified setup considers the shearing of concrete at the centre of the cylindrical container that takes into account the resis...

Sudip Talukdar; Aminul Islam Laskar

2007-01-01

107

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 temperatur...

Alake, O.; Ayangade, J. A.; Wahab, A. B.

2009-01-01

108

A Study of Compressive Strength Characteristics of Laterite Sand Hollow Blocks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 dec...

Abiodun Olanipekun; Olugbenga Ata; Kolapo Olusola; Oludare Omojola

2007-01-01

109

Fracture Energy of High-Strength Concrete in Compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Compression tests are usually carried out in load control. This implies the termination of the test at the peak point of the load-displacement curve, while the fracture under these conditions becomes unstable at the descending branch of the load displacement relation. However, the descending branch 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 proper...

Dahl, Henrik; Brincker, Rune

2011-01-01

110

Fracture Energy of High-Strength Concrete in Compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Compression tests are usually carried out in load control. This implies the termination of the test at the peak point of the load-displacement curve, while the fracture under these conditions becomes unstable at the descending branch of the load displacement relation. However, the descending branch 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 proper...

Dahl, H.; Brincker, Rune

2005-01-01

111

Compressive Strength of Stainless-Steel Sandwiches at Elevated Temperatures  

Science.gov (United States)

Experimental results are presented from crippling tests of stainless-steel sandwich specimens in the temperature range from 80 F to 1,200 F. The specimens included resistance-welded 17-7 PH stainless-steel sandwiches with single-corrugated cores, type 301 stainless-steel sandwiches with double-corrugated cores, and brazed 17-7 PH stainless-steel sandwiches with honeycomb cores. The experimental strengths are compared with predicted buckling and crippling strengths. The crippling strengths were predicted from the calculated maximum strength of the individual plate elements of the sandwiches and from a correlation procedure which gives the elevated-temperature crippling strength when the experimental room-temperature crippling strengths are known. Photographs of some of the tested specimens are included to show the modes of failure.

Mathauser, Eldon E.; Pride, Richard A.

1959-01-01

112

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

Energy Technology Data Exchange (ETDEWEB)

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)

Moelholt Jensen, F.

2003-06-01

113

Effect of compressive loads on the tensile strength of concrete at high strain rates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper describes the behaviour of concrete subjected to tensile loads at high strain rates with and without compressive load histories. The tests, carried out at the laboratory of building materials of the Swiss Federal Institute of Technology, Zurich, show a considerable deterioration of the tensile strength due to initially applied compressive loads.

Tinic, C.; Bru?hwiler, E.

1985-01-01

114

Estimating the concrete compressive strength using hard clustering and fuzzy clustering based regression techniques.  

Science.gov (United States)

Understanding of the compressive strength of concrete is important for activities like construction arrangement, prestressing operations, and proportioning new mixtures and for the quality assurance. Regression techniques are most widely used for prediction tasks where relationship between the independent variables and dependent (prediction) variable is identified. The accuracy of the regression techniques for prediction can be improved if clustering can be used along with regression. Clustering along with regression will ensure the more accurate curve fitting between the dependent and independent variables. In this work cluster regression technique is applied for estimating the compressive strength of the concrete and a novel state of the art is proposed for predicting the concrete compressive strength. The objective of this work is to demonstrate that clustering along with regression ensures less prediction errors for estimating the concrete compressive strength. The proposed technique consists of two major stages: in the first stage, clustering is used to group the similar characteristics concrete data and then in the second stage regression techniques are applied over these clusters (groups) to predict the compressive strength from individual clusters. It is found from experiments that clustering along with regression techniques gives minimum errors for predicting compressive strength of concrete; also fuzzy clustering algorithm C-means performs better than K-means algorithm. PMID:25374939

Nagwani, Naresh Kumar; Deo, Shirish V

2014-01-01

115

A probabilistic mechanical model for prediction of aggregates’ size distribution effect on concrete compressive strength  

Science.gov (United States)

To predict aggregates' size distribution effect on the concrete compressive strength, a probabilistic mechanical model is proposed. Within this model, a Voronoi tessellation of a set of non-overlapping and rigid spherical aggregates is used to describe the concrete microstructure. Moreover, aggregates' diameters are defined as statistical variables and their size distribution function is identified to the experimental sieve curve. Then, an inter-aggregate failure criterion is proposed to describe the compressive-shear crushing of the hardened cement paste when concrete is subjected to uniaxial compression. Using a homogenization approach based on statistical homogenization and on geometrical simplifications, an analytical formula predicting the concrete compressive strength is obtained. This formula highlights the effects of cement paste strength and aggregates' size distribution and volume fraction on the concrete compressive strength. According to the proposed model, increasing the concrete strength for the same cement paste and the same aggregates' volume fraction is obtained by decreasing both aggregates' maximum size and the percentage of coarse aggregates. Finally, the validity of the model has been discussed through a comparison with experimental results (15 concrete compressive strengths ranging between 46 and 106 MPa) taken from literature and showing a good agreement with the model predictions.

Miled, Karim; Limam, Oualid; Sab, Karam

2012-06-01

116

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

DEFF Research Database (Denmark)

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 represented by curves from X-ray diffraction analysis and differential thermogravimetric analysis, as well as particle size distributions. PLS gave maximum explained variance in compressive strength at 1, 2, 7 and 28 days of 93%, 90%, 79% and 67%, respectively. The high explained variance makes the prediction of the compressive strength up to 28 days from the characteristics reliable. The prediction ability makes it possible in this case to predict strength from cement characteristics and vice versa. Such a prediction can be utilized to design a cement to achieve target strength performance.

Svinning, K.; HØskuldsson, Agnar

2008-01-01

117

Prediction of potential compressive strength of Portland clinker from its mineralogy  

DEFF Research Database (Denmark)

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 mineralogy was described by patterns from X-ray diffraction analysis in the 20-regions 29.88-30.70 degrees and 32.90-34.10 degrees (using CuK alpha-radiation). It has been shown that prediction of potential compressive strength of clinker up to 28 d from the observed variation in the mineralogy gave a significant variation of the strength at both 1 and 28 d. Sensitivity analysis based on simulation, optimisation and prediction made it possible to study the influence of the mineralogy on the strength in more detail.

Svinning, K.; HØskuldsson, Agnar

2010-01-01

118

Correlation of Microstructure and Compressive Strength of C/C Composite Using X-ray Tomography  

International Nuclear Information System (INIS)

For the control rod element of a Very High Temperature Reactor, carbon fiber reinforced carbon matrix composite (C/C composite) is one of the major candidate materials for its high strength and thermal stability. In this study, in order to correlate the microstructure of the C/C composite to its compressive strength, the X-ray tomography was applied to visualize the internal microstructure of the C/C composite. The relationship between change in the compressive strength and that in the microstructure was also investigated. This study showed that the pore distribution in the C/C composite could be confirmed visually and the volume and shape of the pores could be evaluated by the X-ray tomography in three-dimension. Moreover, since the matrix was gradually lost and transverse cracks became large with increasing the oxidation, the bonding strength between fiber bundles became weak and the compressive strength of parallel to lamina decreased.

119

Correlation of Microstructure and Compressive Strength of C/C Composite Using X-ray Tomography  

Energy Technology Data Exchange (ETDEWEB)

For the control rod element of a Very High Temperature Reactor, carbon fiber reinforced carbon matrix composite (C/C composite) is one of the major candidate materials for its high strength and thermal stability. In this study, in order to correlate the microstructure of the C/C composite to its compressive strength, the X-ray tomography was applied to visualize the internal microstructure of the C/C composite. The relationship between change in the compressive strength and that in the microstructure was also investigated. This study showed that the pore distribution in the C/C composite could be confirmed visually and the volume and shape of the pores could be evaluated by the X-ray tomography in three-dimension. Moreover, since the matrix was gradually lost and transverse cracks became large with increasing the oxidation, the bonding strength between fiber bundles became weak and the compressive strength of parallel to lamina decreased.

Sumita, J; Shibata, T; Sawa, K [Research Group for VHTR Fuel and Material, Division of Fuels and Materials Engineering, Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, 4002 Oarai-machi, Higashiibaraki-gun, Ibaraki-ken, 311-1393 (Japan); Kunimoto, E; Yamaji, M; Konishi, T, E-mail: sumita.junya@jaea.go.jp [Atomic Energy Section, Production Division, Toyo Tanso Co., Ltd., 2791 Matsuzaki, Takuma-cho, Mitoyoshi, Kagawa-ken, 769-1102 (Japan)

2011-10-29

120

Compression specific toughness of normal strength steel fiber reinforced concrete (NSSFRC) and high strength steel fiber reinforced concrete (HSSFRC)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Compression toughness tests were carried out on concrete cylinders reinforced with three different aspect ratios of hooked-end steel fibers 60, 75, and 83 and six different percentages of steel fibers 0.5, 1.0, 1.25, 1.5, 1.75, and 2.0% by volume of concrete. The w/c ratio used for the normal streng [...] th steel fiber reinforced concrete mixes (NSSFRC) was 0.55, and the water-cementitious ratio (w/c+s) for the high strength fiber reinforced concrete mixes (HSSFRC) was 0.31. For each mix, three test cylinders were tested for compression specific toughness. The effect of fiber reinforcement index: volume of fibers × length/diameter ratio on compression specific toughness and also on the relationship between these two properties is presented in this paper. As a result, (a) equations are proposed to quantify the effect of fibers on compression toughness ratio of concrete in terms of FRI, (b) equations obtained in terms of FRI and compression specific toughness of plain concrete to estimate both compression specific toughness of NSSFRC and HSSFRC (N.m), (c) equations obtained which represent the relationship between compression toughness index and FRI for NSSFRC and HSSFRC, respectively, and (d) equations obtained to quantify the relationship between compression specific toughness index and fiber reinforcement index for NSSFRC and HSSFRC, respectively. The proposed equations give good correlation with the experimental values.

Khaled, Marara; Özgür, Erenb; & #304; brahim, Yitmena.

 
 
 
 
121

Developing a forecasting model of concrete compressive strength using relevance vector machines  

Directory of Open Access Journals (Sweden)

Full Text Available We analyze results of two experiments that tested effect of adding Silica on the compressive strength of concrete at early stage and after long period. The two experiments evaluated different silica/cement ratios for different mixing periods. Adding Silica to concrete mix produce high early strength material which is highly desirable in airports and highways. More than 90 samples of different silica/cement ratios are tested for compressive strength at 3 and 28 days. Test results showed high early up to 60 MPa. Strength increase is proportional with the increase of silica/cement ratio and mixing time with maximum at ratio of 15/100 and 30 minutes mixing time. A relevance Vector Machine (RVM model is developed to predict concrete compressive strength using concrete mixture inputs information. RVM model predictions matched experimental data closely.  The developed model can be used to predict compressive strength in future periods based on initial information related to cement mixture.   Keywords: Relevance Vector Machine, Silicate Percent, Prediction Model, Milling Time, Compressive Strength, Concrete.

Mohammad Awwad

2014-03-01

122

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

Directory of Open Access Journals (Sweden)

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 por pasta de cemento más arena normal y otra "ligera", formada por árido grueso ligero. La primera aporta la resistencia estructural y la segunda disminuye la densidad del hormigón. De esta forma sería posible describir el comportamiento mecánico del hormigón en función de parámetros del árido ligero y del mortero de cemento. A partir de los resultados se proponen relaciones entre las propiedades mecánicas del HLE (resistencia a compresión y rigidez y las propiedades y cantidad de los materiales constituyentes. Asimismo, se propone un índice para caracterizar la capacidad estructural del árido ligero, que es de fácil medición y permite estimar las propiedades mecánicas potenciales del hormigón que se podrían obtener con el uso de un árido determinado.

Videla, C.

2002-03-01

123

Compressive strength of composites: How to measure it and how to improve it  

International Nuclear Information System (INIS)

The compressive strength of unidirectional fiber composites is an important parameter but is nevertheless much misunderstood. The authors can neither agree on how to measure it, nor what are the physical processes that give rise to it. It is important because it provides a limiting design criterion. Furthermore, the authors cannot start to understand the compressive failure of more complex laminates until the authors understand that of the simplest, i.e. unidirectional laminate. This paper discusses both problems, suggests solutions, and makes recommendations on how to obtain the best compressive strength

124

Influence of the real density and structure imperfection of hollow glass microspheres on the compression strength  

Energy Technology Data Exchange (ETDEWEB)

Highlights: {yields} A new formula for calculating the compression strength of hollow glass microspheres was proposed. {yields} Chemical composition of HGM was analyzed. {yields} Imperfect structure was characterized by optical microscope. {yields} Structure defects were characterized by SEM after heat treating at 700 deg. C. {yields} Strength of samples with same structure coefficient increases with real density. - Abstract: In this paper, we simplified the factors that affect the compression strength of hollow glass microspheres theoretically. When the chemical composition of the hollow glass microspheres was determined, the real density was the only variable to decide the strength. We calculated the theoretical strength of sample - T, Tg1, Tg2, S, A and R according to their chemical composition and real density. The real strength of the hollow glass microspheres was much lower than the theoretical strength actually due to the structure imperfection. The structure defect was characterized by optical microscope and scanning electron microscope (samples for scanning electron microscope have been treated under 700 deg. C). The real strength 'P{sub r}' should be decided by the theoretical strength 'P' multipied by a structure coefficient '{phi}', which is related to the preparation technology closely. The sample-T was graded in grain size with a water separator to get samples with the same structure coefficient but varied in real density. The results of compression test proved that the strength increased with the real density.

Yan Kaiqi; Xie Xiao; Li Bing; Yuan Jing [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate School of Chinese Academy of Sciences, Beijing 100049 (China); Zhang Jingjie, E-mail: catchyqi@yahoo.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2011-11-15

125

Influence of the real density and structure imperfection of hollow glass microspheres on the compression strength  

International Nuclear Information System (INIS)

Highlights: ? A new formula for calculating the compression strength of hollow glass microspheres was proposed. ? Chemical composition of HGM was analyzed. ? Imperfect structure was characterized by optical microscope. ? Structure defects were characterized by SEM after heat treating at 700 deg. C. ? Strength of samples with same structure coefficient increases with real density. - Abstract: In this paper, we simplified the factors that affect the compression strength of hollow glass microspheres theoretically. When the chemical composition of the hollow glass microspheres was determined, the real density was the only variable to decide the strength. We calculated the theoretical strength of sample - T, Tg1, Tg2, S, A and R according to their chemical composition and real density. The real strength of the hollow glass microspheres was much lower than the theoretical strength actually due to the structure imperfection. The structure defect was characterized by optical microscope and scanning electron microscope (samples for scanning electron microscope have been treated under 700 deg. C). The real strength 'Pr' should be decided by the theoretical strength 'P' multipied by a structure coefficient '?', which is related to the preparation technology closely. The sample-T was graded in grain size with a water separator to get samples with the same structure coefficient but varied in real density. The results of compression test proved that the strengion test proved that the strength increased with the real density.

126

Experimental Study of Confined Low-, Medium- and High-Strength Concrete Subjected to Concentric Compression  

Directory of Open Access Journals (Sweden)

Full Text Available An experimental study of 23 low-, medium- and high-strength concrete columns is presented in this paper. Square-confined concrete columns without longitudinal reinforcement were designed, and tested under concentric axial compression. The columns were made of concrete with a compressive strength ranging between 30 MPa and 70 MPa. The test parameters in the study are concrete compressive strengths and confining steel properties, i.e. spacing, volumetric ratios and configurations. The effects of these parameters on the strength and ductility of square-confined concrete were evaluated. Of the specimens tested in this study, the columns made with higher-strength concrete produced less strength enhancement and ductility than those with lower-strength concrete. The steel configurations were found to have an important role in governing the strength and ductility of the confined high-strength concrete. Moreover, several models of strength enhancement for confined concrete available in the literature turned out to be quite accurate in predicting the experimental results.

Antonius

2012-11-01

127

Green and early age compressive strength of extruded cement mortar monitored with compression tests and ultrasonic techniques  

International Nuclear Information System (INIS)

Knowledge about the early age compressive strength development of cementitious materials is an important factor for the progress and safety of many construction projects. This paper uses cylindrical mortar specimens produced with a ram extruder to investigate the transition of the mortar from plastic and deformable to hardened state. In addition, wave transmission and reflection measurements with P- and S-waves were conducted to obtain further information about the microstructural changes during the setting and hardening process. The experiments have shown that uniaxial compression tests conducted on extruded mortar cylinders are a useful tool to evaluate the green strength as well as the initiation and further development of the compressive strength of the tested material. The propagation of P-waves was found to be indicative of the internal structure of the tested mortars as influenced, for example, by the addition of fine clay particles. S-waves used in transmission and reflection mode proved to be sensitive to the inter-particle bonding caused by the cement hydration and expressed by an increase in compressive strength

128

Laboratory Investigation on Performance of Cement Using Different Additives Schemes to Improve Early Age Compressive Strength  

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Full Text Available It is essential to maintain the oil well cement integrity effectively and economically. The classical literature review of cement slurry preparation has shown high temperature in wellbore has influenced the mechanical properties of cement slurry, especially compressive strength. The compressive strength is the most important parameter when the ability of the cement to perform its necessary functions of down-hole faster placement analyzed. In past, the different additives were used to improve the performance of cement slurry by maintain compressive strength during placement. Laboratory tests carry out by Silica Fume (SF with dispersants and fluid loss control additives at different concentrations to performed early age compressive test of nondestructive cement slurry through Ultra-Sonic Cement Analyzer (UCA. Measured result showed that 6:34 and 7:48 h aged sample have a maximum compressive strength at temperature above 120°C. It is observed that as concentration of SF increased with combined dispersants and fluid loss additives used to control& enhance compressive strength at above 120°C for the integrity of cement slurry.

Muhannad Talib Shuker

2014-03-01

129

Improving the Bearing Strength of Sandy Loam Soil Compressed Earth Block Bricks Using Sugercane Bagasse Ash  

Directory of Open Access Journals (Sweden)

Full Text Available The need for affordable and sustainable alternative construction materials to cement in developing countries cannot be underemphasized. Compressed Earth Bricks have gained acceptability as an affordable and sustainable construction material. There is however a need to boost its bearing capacity. Previous research show that Sugarcane Bagasse Ash as a soil stabilizer has yielded positive results. However, there is limited research on its effect on the mechanical property of Compressed Earth Brick. This current research investigated the effect of adding 3%, 5%, 8% and 10% Sugarcane Bagasse Ash on the compressive strength of compressed earth brick. The result showed improvement in its compressive strength by 65% with the addition of 10% Sugarcane Bagasse Ash.

Ramadhan W. Salim

2014-06-01

130

Prediction of Compressive Strength of Concrete using Artificial Neural Network  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Concrete cube strength determination tests are usually performed at three days to one year afterpouring the concrete. The waiting period required to perform such test may delay the construction progress,decision making and neglecting such test would limit the quality control checks in large constructionprojects. Therefore it becomes necessary that the rapid and reliable prediction of concrete strength isessential for pre-design or quality control of construction. It is possible to facilitate ...

Wankhade M W

2013-01-01

131

Compressive strength after blast of sandwich composite materials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Composite sandwich materials have yet to be widely adopted in the construction of naval vessels despite their excellent strength-to-weight ratio and low radar return. One barrier to their wider use is our limited understanding of their performance when subjected to air blast. This paper focuses on this problem and specifically the strength remaining after damage caused during an explosion. Carbon-fibre-reinforced polymer (CFRP) composite skins on a styrene–acrylonitrile (SAN) polymer closed...

Arora, H.; Kelly, M.; Worley, A.; Del Linz, P.; Fergusson, A.; Hooper, P. A.; Dear, J. P.

2014-01-01

132

Prediction of the compressive strength of vertebral bodies of the lumbar spine by quantitative computed tomography  

International Nuclear Information System (INIS)

The ultimate compressive strength of 36 thoracolumbar vertebrae was determined experimentally. In addition, the trabecular bone mineral content was measured by single energy quantitative computed tomography. The areas of fractured endplates were also determined by computed tomography. The results show that a linear relationship exists betwen the compressive strength and the product of bone density and endplate area. These data allow an in vivo prediction of vertebral body strength using a noninvasive method with a standard error of estimate amounting to less than 0.95 kN. (orig.)

133

Prediction of the compressive strength of vertebral bodies of the lumbar spine by quantitative computed tomography  

Energy Technology Data Exchange (ETDEWEB)

The ultimate compressive strength of 36 thoracolumbar vertebrae was determined experimentally. In addition, the trabecular bone mineral content was measured by single energy quantitative computed tomography. The areas of fractured endplates were also determined by computed tomography. The results show that a linear relationship exists betwen the compressive strength and the product of bone density and endplate area. These data allow an in vivo prediction of vertebral body strength using a noninvasive method with a standard error of estimate amounting to less than 0.95 kN.

Biggemann, M.; Hilweg, D.; Brinckmann, P.

1988-06-01

134

Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Olusola K.O.; Olawuyi B.J.

2010-01-01

135

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

Science.gov (United States)

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. PMID:24094224

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

2013-12-01

136

The estimation of compressive strength of normal and recycled aggregate concrete  

Directory of Open Access Journals (Sweden)

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.

Jankovi? Ksenija

2011-01-01

137

Effect of specimen sizes, specimen shapes, and placement directions on compressive strength of concrete  

International Nuclear Information System (INIS)

The compressive strength of concrete is used as the most basic and important material property when reinforced concrete structures are designed. It has become a problem to use this value, however, because the control specimen sizes and shapes may be different from country to country. In this study, the effect of specimen sizes, specimen shapes, and placement directions on compressive strength of concrete specimens was experimentally investigated based on fracture mechanics. Experiments for the Mode I failure were carried out by using cylinder, cube, and prism specimens. The test results are curve-fitted using least square method (LSM) to obtain the new parameters for the modified size effect law (MSEL). The analysis results show that the effect of specimen sizes, specimen shapes, and placement directions on ultimate strength is present. In addition, correlations between compressive strengths with size, shape, and placement direction of the specimen are investigated

138

Numerical validation of compressive strength prediction for hollow concrete blocks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The results of a numerical modeling program to evaluate the behavior of hollow concrete blocks under uniaxial compression are addressed. It has been considered appropriate to use interface elements to represent the confinement effect at the top and bottom of blocks. The response of the numerical simulations is compared with experimental data of masonry units. Laboratory tests were carried out utilizing standard flat platens and brush platens to evaluate the confinement effect due ...

Barbosa, C. S.; Hanai, J. B.; Lourenc?o, Paulo B.

2010-01-01

139

On the compressive strength prediction for concrete masonry prisms  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The results of a combined experimental program and numerical modeling program to evaluate the behavior of ungrouted hollow concrete blocks prisms under uniaxial compression are addressed. In the numerical program, three distinct approaches have been considered using a continuum model with a smeared approach, namely plane-stress, plane-strain and three-dimensional conditions. The response of the numerical simulations is compared with experimental data of masonry prisms using concrete blocks sp...

Barbosa, C. S.; Lourenc?o, Paulo B.; Hanai, J. B.

2010-01-01

140

Permeability, porosity and compressive strength of self-compacting concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 streng...

Valcuende, M. O.; Parra, C.; Benlloch, J.

2005-01-01

 
 
 
 
141

Compressive Strength of Notched Poly(Phenylene Sulfide) Aerospace Composite: Influence of Fatigue and Environment  

Science.gov (United States)

The purpose of this work is to evaluate the influences of fatigue and environmental conditions (-55 °C, 23 °C, and 82 °C/Wet) on the ultimate compression strength of notched carbon-fiber-reinforced poly(phenylene sulfide) composites by performing open-hole compression (OHC) tests. Analysis of the fatigue effect showed that at temperatures of -55 and 23 °C, the ultimate OHC strengths were higher for fatigued than for not-fatigued specimens; this could be attributed to fiber splitting and delamination during fatigue cycling, which reduces the stress concentration at the hole edge, thus increasing the composite strength. This effect of increasing strength for fatigued specimens was not observed under the 82 °C/Wet conditions, since the test temperature near the matrix glass transition temperature ( T g) together with moisture content resulted in matrix softening, suggesting a reduction in fiber splitting during cycling; similar OHC strengths were verified for fatigued and not-fatigued specimens tested at 82 °C/Wet. Analysis of the temperature effect showed that the ultimate OHC strengths decreased with increasing temperature. A high temperature together with moisture content (82 °C/Wet condition) reduced the composite compressive strengths, since a temperature close to the matrix T g resulted in matrix softening, which reduced the lateral support provided by the resin to the 0° fibers, leading to fiber instability failure at reduced applied loads. On the other hand, a low temperature (-55 °C) improved the compressive strength because of possible fiber-matrix interfacial strengthening, increasing the fiber contribution to compressive strength.

Niitsu, G. T.; Lopes, C. M. A.

2013-08-01

142

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

Science.gov (United States)

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. PMID:23351273

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

2013-07-01

143

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

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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.

Hongying Dong

2014-12-01

144

Investigation of adding fluoroapatite nanoparticles on compressive strength and corrosion behaviour of dental amalgams  

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Full Text Available In recent years, there have been many efforts to improve biological and biocompatibility features of amalgam. The aim of this research was investigating the effect of adding fluoroapatite (FA nanoparticles on compressive strength and corrosion behaviour of dental amalgam. An amalgam alloy powder was mixed with 1, 3 and 5 wt.% of FA nanoparticles to form composite powders. Compressive strength of the corresponding dental amalgam samples was measured on the first and seventh day after preparation and the corrosion behaviour was investigated by potentiodynamic polarization electrochemical test in 0.9 wt.% salt solution (physiologic serum. The results showed that the amalgam containing 1 wt.% FA nanoparticles has higher compressive strength then the pure amalgam and with increasing the FA content in amalgam to 3 and 5 wt.%, the compressive strength decreases. The results also indicated that the corrosion behaviour of the amalgam sample with 1 wt.% FA is similar to the corrosion behaviour of the original amalgam, while with increasing the weight percentage of fluorapatite, the corrosion resistance decreases. The results of this research showed that adding FA nanoparticles in amounts of up to 1 wt.% to amalgam alloy improve compressive strength, has no destructive effect on corrosion behaviour of the material and can increase its biocompatibility and biological activity.

Fahimeh Mirlohi

2012-12-01

145

Hydraulic efficiency compromises compression strength perpendicular to the grain in Norway spruce trunkwood.  

Science.gov (United States)

The aim of this study was to investigate bending stiffness and compression strength perpendicular to the grain of Norway spruce (Picea abies (L.) Karst.) trunkwood with different anatomical and hydraulic properties. Hydraulically less safe mature sapwood had bigger hydraulic lumen diameters and higher specific hydraulic conductivities than hydraulically safer juvenile wood. Bending stiffness (MOE) was higher, whereas radial compression strength lower in mature than in juvenile wood. A density-based tradeoff between MOE and hydraulic efficiency was apparent in mature wood only. Across cambial age, bending stiffness did not compromise hydraulic efficiency due to variation in latewood percent and because of the structural demands of the tree top (e.g. high flexibility). Radial compression strength compromised, however, hydraulic efficiency because it was extremely dependent on the characteristics of the "weakest" wood part, the highly conductive earlywood. An increase in conduit wall reinforcement of earlywood tracheids would be too costly for the tree. Increasing radial compression strength by modification of microfibril angles or ray cell number could result in a decrease of MOE, which would negatively affect the trunk's capability to support the crown. We propose that radial compression strength could be an easily assessable and highly predictive parameter for the resistance against implosion or vulnerability to cavitation across conifer species, which should be topic of further studies. PMID:22058609

Rosner, Sabine; Karlsson, Bo

2011-04-01

146

Compressive strength, flexural strength and thermal conductivity of autoclaved concrete block made using bottom ash as cement replacement materials  

International Nuclear Information System (INIS)

Highlights: ? Autoclaved aerated concrete were produced using coal bottom ash as a cement replacement material. ? Coal bottom ash was found to enhance concrete strengths. ? Thermal conductivity of concrete was not significantly affected. ? X-ray diffraction and thermal analysis show tobermorite formation. -- Abstract: The bottom ash (BA) from Mae Moh power plant, Lampang, Thailand was used as Portland cement replacement to produce lightweight concrete (LWC) by autoclave aerated concrete method. Portland cement type 1, river sand, bottom ash, aluminium powder and calcium hydroxide (Ca(OH)2) were used in this study. BA was used to replace Portland cement at 0%, 10%, 20% and 30% by weight and aluminium powder was added at 0.2% by weight in order to produce the aerated concrete. Compressive strength, flexural and thermal conductivity tests were then carried out after the concrete were autoclaved for 6 h and left in air for 7 days. The results show that the compressive strength, flexural strength and thermal conductivity increased with increased BA content due to tobermorite formation. However, approximately, 20% increase in both compressive (up to 11.61 MPa) and flexural strengths (up to 3.16 MPa) was found for mixes with 30% BA content in comparison to just around 6% increase in the thermal conductivity. Thermogravimetry analysis shows C–S–H formation and X-ray diffraction confirm tobermorite formation in bottom ash lightweight concrete. The use of BA as a cement replacement, therefore, can be seen to have the benefit in enhancing strength of the aerated concrete while achieving comparatively low thermal conductivity when compared to the results of the control Portland cement concrete.

147

Effect of activator solution on compressive strength of flyash geopolymer blended with slag  

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Full Text Available The influence of the composition of activator solution on the strength of fly ash geopolymer blended with slag was investigated. The research variable include % Na2O and sodium silicate under typical controlled parameters like curing profile, water content, base material and supplementary material. In this study, the monitoring response variable was compressive strength. Finding suggests that activator solution combination has a significant effect on the properties of the GP (non-blended geopolymer and GB (geopolymer blended with 15% slag. The experiment concludes that higher percentage of Na2O gives lower strength for GB specimens but corresponding higher strength for GP specimens. Silicate modulus has similar impact on GP and GB. Both for GP and GB specimens compressive strength is increase with higher silicate modulus.

Debabrata Dutta

2014-12-01

148

Prediction of Uniaxial Compressive Strength, Tensile Strength and Porosity of Sedimentary Rocks Using Sound Level Produced During Rotary Drilling  

Science.gov (United States)

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, tensile strength and percentage porosity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of various predictor variables. Predictor variables selected for the multiple regression model are drill bit diameter, drill bit speed, penetration rate and equivalent sound level produced during rotary drilling ( L eq). The constructed models were checked using various prediction performance indices. Consequently, it is possible to say that the constructed models can be used for practical purposes.

Rajesh Kumar, B.; Vardhan, Harsha; Govindaraj, M.

2011-09-01

149

Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete  

Directory of Open Access Journals (Sweden)

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.

Olusola K. O.

2010-01-01

150

Effect of pH on compressive strength of some modification of mineral trioxide aggregate  

Science.gov (United States)

Objectives: Recently, it was shown that NanoMTA improved the setting time and promoted a better hydration process which prevents washout and the dislodgment of this novel biomaterial in comparison with WTMA. This study analyzed the compressive strength of ProRoot WMTA (Dentsply), a NanoWMTA (Kamal Asgar Research Center), and Bioaggregate (Innovative Bioceramix) after its exposure to a range of environmental pH conditions during hydration. Study Design: After mixing the cements under aseptic condition and based on the manufacturers` recommendations, the cements were condensed with moderate force using plugger into 9 × 6 mm split molds. Each type of cement was then randomly divided into three groups (n=10). Specimens were exposed to environments with pH values of 4.4, 7.4, or 10.4 for 3 days. Cement pellets were compressed by using an Instron testing machine. Values were recorded and compared. Data were analyzed by using one-way analysis of variance and a post hoc Tukey’s test. Results: After 3 days, the samples were solid when probed with an explorer before removing them from the molds. The greatest mean compressive strength 133.19±11.14 MPa was observed after exposure to a pH value of 10.4 for NanoWMTA. The values decreased to 111.41±8.26 MPa after exposure to a pH value of 4.4. Increasing of pH had a significant effect on the compressive strength of the groups (p<0.001). The mean compressive strength for the NanoWMTA was statistically higher than for ProRoot WMTA and Bioaggregate (p<0.001). Moreover, increasing of pH values had a significant effect on compressive strength of the experimental groups (p<0.001). Conclusion: The compressive strength of NanoWMTA was significantly higher than WMTA and Bioaggregate; the more acidic the environmental pH, the lower was the compressive strength. Key words:Compressive strength, mineral trioxide aggregate, Nano. PMID:23722137

Saghiri, Mohammad A.; Garcia-Godoy, Franklin; Asatourian, Armen; Lotfi, Mehrdad; Khezri-Boukani, Kaveh

2013-01-01

151

Residual Compressive Strength of Laterized Concrete Subjected to Elevated Temperatures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Brooks, Robert M.

2010-01-01

152

Dynamic compressive and tensile strengths of spark plasma sintered alumina  

Energy Technology Data Exchange (ETDEWEB)

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 Cr{sub 2}O{sub 3} decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

Girlitsky, I.; Zaretsky, E. [Department of Mechanical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Kalabukhov, S.; Dariel, M. P.; Frage, N. [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

2014-06-28

153

Correlation between uniaxial compressive strength and point load index for salt-range rocks  

International Nuclear Information System (INIS)

Nine rock types including Sandstone, Limestone, Siltstone, Dolomite and Marl collected from six different rock formations of the Salt Range area of Pakistan were tested to evaluate the correlations between the uniaxial compressive strength and the corresponding values of the point load index. Two hundred rock cores were drilled and used for the uniaxial compressive strength and point load index tests. Results indicate the existence of two rock groups showing distinct behaviour in the context of this correlation. The first group of rocks, Group A, consists of hard Jutana Sandstone, Baghanwala Sandstone, Siltstone, Sakessar Massive Limestone, Khewra Sandstone and Dolomite. The second group of rocks, Group B, consists of relatively soft Dandot Sandstone, Sakessar Nodular Limestone and Marl. The correlation equations for predicting compressive strength using point load index for each group are presented along with their confidence limits to show the variability of results produced from each equation. (author)

154

Effects of densified silica fume on microstructure and compressive strength of blended cement pastes  

International Nuclear Information System (INIS)

Some experimental investigations on the microstructure and compressive strength development of silica fume blended cement pastes are presented in this paper. The silica fume replacement varies from 0% to 20% by weight and the water/binder ratio (w/b) is 0.4. The pore structure by mercury intrusion porosimetry (MIP), the micromorphology by scanning electron microscopy (SEM) and the compressive strength at 3, 7, 14, 28, 56 and 90 days have been studied. The test results indicate that the improvements on both microstructure and mechanical properties of hardened cement pastes by silica fume replacement are not effective due to the agglomeration of silica fume particles. The unreacted silica fume remained in cement pastes, the threshold diameter was not reduced and the increase in compressive strength was insignificant up to 28 days. It is suggested that the proper measures should be taken to disperse silica fume agglomeration to make it more effective on improving the properties of materials

155

Statistical approach to predict compressive strength of high workability slag-cement mortars  

International Nuclear Information System (INIS)

This paper reports an attempt made to develop empirical expressions to estimate/ predict the compressive strength of high workability slag-cement mortars. Experimental data of 54 mix mortars were used. The mortars were prepared with slag as cement replacement of the order of 0, 50 and 60%. The flow (workability) was maintained at 136+-3%. The numerical and statistical analysis was performed by using database computer software Microsoft Office Excel 2003. Three empirical mathematical models were developed to estimate/predict 28 days compressive strength of high workability slag cement-mortars with 0, 50 and 60% slag which predict the values accurate between 97 and 98%. Finally a generalized empirical mathematical model was proposed which can predict 28 days compressive strength of high workability mortars up to degree of accuracy 95%. (author)

156

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

Science.gov (United States)

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.

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

1975-01-01

157

Improved compressive strength ordered polymer fibers via radiation-induced cross-linking  

International Nuclear Information System (INIS)

Radiation cross-linking was successfully applied to increase the compressive strength of ordered polymer fibers. PBO, PBO/IP-600, methyl-PBZT and dimethyl-PBZT fibers were irradiated with proton, electron and gamma rays at varying doses. The compressive strength of PBO fiber was doubled by proton irradiation and dimethyl-PBZT fiber was improved more than 50 percent by electron irradiation. PBO/IP-600 and methyl-PBZT fibers were not noticeably improved by irradiation. Fiber swelling studies at M.I.T. confirmed the cross-linking mechanism for protons and electrons, but not gamma rays. The results of efforts to improve the compressive strength of ordered polymer fibers are discussed

158

Effect of Different Cure Conditions on Compressive Strength of Concrete Having Different Properties  

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Full Text Available This research was carried out to determine unit weights and compressive strengths for the concrete samples produced with normal aggregate obtained Erzurum province and lightweight aggregate obtained Van-Ercis province and cured under different conditions. Unit weights of concrete specimens produced with normal aggregate were 2325 under air cure, 2360 under water cure, 2358 kg m-3 under steam cure. Unit weights of concrete specimens produced with lightweight aggregate were 906 under air cure, 1060 under water cure, 972 kg m-3 under steam cure. In average, 28 days compressive strength of concrete specimens produced with normal aggregate were 180.3 under air cure, 270.0 under water cure, 240.1 kgf cm-2 under steam cure. In average 28 days compressive strength of concrete specimens produced with lightweight aggregate were 60.0 under air cure, 45.2 under water cure, 52.4 kgf cm-2 under steam cure.

Canan Kose

2011-01-01

159

A Study of Compressive Strength Characteristics of Laterite Sand Hollow Blocks  

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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.

Abiodun Olanipekun

2007-01-01

160

The Study of Green Compression Strength of a Green Sand Mould Using Statistical Approach  

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The study of green compression strength of a green sand mould using statistical approach has been undertaken. Empirically generated data in National Metallurgical Development Centre, Jos Sand Testing Laboratory were used for the study. Coefficient of correlation, coefficients of determination and coefficient of multiple determinations were used to explain the relationship existing between the two independent variables of clay and moisture content and green compression streng...

Aondona Paul Ihom; Aniekan Offiong

2014-01-01

 
 
 
 
161

Compressive strength degradation in ZrB2-based ultra-high temperature ceramic composites  

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The high temperature compressive strength behavior of zirconium diboride (ZrB2)-silicon carbide (SiC) particulate composites containing either carbon powder or SCS-9a silicon carbide fibers was evaluated in air. Constant strain rate compression tests have been performed on these materials at room temperature, 1400, and 1550°C. The degradation of the mechanical properties as a result of atmospheric air exposure at high temperatures has also been studied as a function of exposure time. The Z...

Rami?rez-rico, J.; Bautista, M. A.; Marti?nez-ferna?ndez, Julia?n; Singh, M.

2011-01-01

162

A synthetic aragonite-based bioceramic: influence of process parameters on porosity and compressive strength.  

Science.gov (United States)

We investigate the influence of process parameters such as weight fraction and particle size of pore-former, and isostatic pressure, on porosity and compressive strength of non-sintered porous calcium carbonate biomaterials compacted at high pressure in uniaxial or isostatic mode. Experiment design and results analysis are performed according to a two-level 2k factorial design method (FDM). Results indicate that only the weight fraction of pore-former (wt fpf) influences significantly the porosity and the compressive strength. The porosity P, is described by a linear function of wt fpf, and the compressive strength sigma(comp), by an exponential one. For materials compacted under uniaxial pressing: P (vol%) = 33.7 + 85.4 (wt fpf) and sigma(comp) (MPa) = 28.8e(-9.2(wt fpf)) with 0.1 < or = wt fpf < or = 0.3. For materials compacted in isostatic mode: P (vol%) = 33.9 + 82.1 (wt fpf) and sigma(comp) (MPa) = 24.0e(-7.0(wt fpf)) with 0.15 < or = wt fpf < or = 0.35. The pore-former particle size has no significant influence on both properties. The increase in isostatic pressure provides slightly lower porosity and better compressive strength. For a fixed fraction of pore-former, isostatic pressing leads to a better compressive strength than uniaxial pressing. This study indicates that, for a constant amount of pore former, the size of macropores can be adjusted to reach optimal bone-ingrowth without change in compressive strength. PMID:11761171

Luca-Girot, A; Langlois, P; Sangleboeuf, J C; Ouammou, A; Rouxel, T; Gaude, J

2002-01-01

163

Micromechanical strength effects in shock compression of solids  

International Nuclear Information System (INIS)

Time-resolved shock-wave measurements and post-shock recovery techniques have long been used as means of inferring the underlying micromechanics controlling high-rate deformation of solids. This approach requires a considerable amount of subjective interpretation. In spite of this feature, progress has been made in experimentation and theoretical interpretation of the shock-compression/release cycle and some of the results are reviewed here for weak shocks. Weak shocks are defined to be those with peak amplitudes (typically 10--20 GPa for most solids) that do not overdrive the elastic precursor. The essential elements of a typical shock-compression/release cycle involve, in order, (a) the elastic precursor, (b) plastic loading wave, (c) pulse duration, (d) release wave, and (e) post-mortem examination. These topics are examined in turn, with some emphasis given to elements (b) and (d). If the plastic loading wave is traveling without change of shape, it is possible to convert the particle-velocity/time records to a shear-stress/plastic-strain-rate path. Shock data in this form can be compared directly with low-to-intermediate strain-rate tests. Results for copper and tantalum show how shock data can be used to determine the transition from the deformation mechanism of thermal activation to that of dislocation drag. An important result of release-wave studies is that the leading observable release disturbance in FCC metals may not be propagating with the ideal, longitunot be propagating with the ideal, longitudinal elastic-wave speed, but at a lower velocity dependent on the elastic bulk and shear moduli and the product of the dislocation density times the pinning separation squared for dislocation segments in the region behind the shock and ahead of the release wave. copyright 1994 American Institute of Physics

164

Fatigue and static strengths of fine-grained isotropic graphite by ring compression test  

International Nuclear Information System (INIS)

Fatigue and static strength tests of unirradiated and irradiated fine-grained isotropic graphite IG-110 were performed with three types of ring specimens. These specimens were irradiated in the condition of 575 ? 650 deg C and 1.92 x 1020 ? 3.20 x 1020 n/cm2 (E > 0.18 MeV). The conclusions were derived; (1) The characteristics of static strength and strength distribution of ring compressive test was different from that of another strength tests. In order of mean strength of each strength tests, ring > 3 point > 4 point > uniform tension, and in order of dispersion of data, ring < 3 point < 4 point < uniform tension. (2) Fatigue strength tested by ring compressive test was lower than that tested by uniform tension-tension fatigue test. (3) Strength of the irradiated ring specimens increased about 1.2 times that of the unirradiated. (4) Fatigue strength of the irradiated ring specimens were increased about 1.2 times that of unirradiated. (author)

165

The statitistical evaluation of the uniaxial compressive strength of the Ruskov andesite  

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Full Text Available The selection of a suitable model of the statistical distribution of the uniaxial compressive strength is discussed in the paper. The uniaxial compressive strength was studied on 180 specimens of the Ruskov andesite. The rate of loading was 1MPa.s-1. The experimental specimens had a prismatic form with a square base; the slightness ratio of specimens was 2:1. Three sets of specimens with a different length of the base edge were studied, namely 50, 30 and 10 mm. The result of the measurement were three sets with 60 values of the uniaxial compressive strength. The basic statistical parameters: the sample mean, the sample standard deviation, the variational interval, the minimum and maximum value, the sample obliqueness coefficient and the sharpness coefficient were evaluated for each collection. Two types of the distribution which can be joined with the real physical fundamentals of the desintegration of rocks ( the normal and the Weibull distribution were tested. The two-parametric Weibull distribution was tested. The basic characteristics of both distributions were evaluated for each set and the accordance of the model distribution with an experimental distribution was tested. The ÷2-test was used for testing. The two-parametric Weibull distribution was selected following the comparison of the test results of both model distributions as a suitable distribution model for the characterization of uniaxial compressive strength of the Ruskov andesite. The two-parametric Weibull distribution showed better results of the goodness-of-fit test. The normal distribution was suitable for two sets; one of the sets showed a negative result of the goodness-of-fit testing. At the uniaxial compressive strength of the Ruskov andesite, a scale effect was registered : the mean value of uniaxial compressive strength decreases with increasing the specimen base edge. This is another argument for using the Weibull distribution as a suitable statistical model of the uniaxial compressive strength distribution. The Weibull distribution unlike the normal distribution enables the physical interpretation of the scale effect influence on uniaxial compressive strength value.

Krepelka František

2002-03-01

166

The Comparison of the Film Thickness and Compressive Strength Between Ariadent and Harvard Zinc Phosphate Cement.  

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Full Text Available Introduction. Recently, the Ariadent Zinc phosphate cement has been introduced to market with low cost. Some dentists purchase this product because of low cost and others avoid buying it because of unreliable quality. The two important properties of ideal dental cement are to have the minimum film thickness (less than 25 micron and to have favorable compressive strength. The purpose of this study was to determine the mean and to compare the film thickness and compressive strength of Ariadent and Harvard Zinc phosphate cement.Materials and Methods. In this experimental study evaluation was made based on Iranian standard number 2725. To measure film thickness of each cement, the first step was to prepare two glass slabs and their thickness was measured with micrometer, then each cement was prepared according to standard procedure and was put between the glass slabs. The difference between glass slabs with and without cement was measured. This procedure was repeated 3 times and average of three measurements were obtained and determined as mean of cement film thickness. To determine the compressive strength of each cement at first a mold was fabricated according to standard procedures. Then each prepared cement was poured in to the mold. After 24 hours each of five prepared specimens was Put under load and the average compressive strength was calculated.Results. The mean film thickness for Arident Zinc phosphate was 42.33?4.50 micron and for Harvard cement was 24.33?5.70. The mean compressive strength of Ariadent Zinc phosphate cement was 44.90?4.11 MPa and for Harvard cement was 62.85?5.19 MPa. The statistical analysis (t-student revealed significant difference between two phosphate cement.Discussion. In this study mean film thickness of Iranian Ariadent Zinc phosphate cement was more than standard level (25 micron and the mean compressive strength was less than standard level (70 MPa. These results indicated that Ariadent cement was of low quality and below standard. But Harvard Zinc phosphate cement had a standard film thickness and its compressive strength was close to standard and this is a reason for acceptable quality of Harvard Zinc phosphate cement.Keywords. Cement, Compressive strength, film thickness, Zinc phosphate cement

M - Sabouhi

2005-01-01

167

The chemical composition and compression strengths of refractory ceramics, tested for 3 curing temperatures  

International Nuclear Information System (INIS)

An investigation was carried out to determine and compile the mechanical strength of a refractory ceramic made of ground fire bricks and refractory fire mortar. Three different compositions were studied for the compression strength and it was found that the composition with 50% fire bricks and 50% fire mortar gives the best mechanical strength. With this composition the maximum failure compression stress is 3.2 MPa. and the Young Modulus is 403.5 MPa. The investigation also shows that the curing temperatures and the composition percentages play an important role in determining the strength of the ceramic. The trend obtained from the investigation shows that there is the possibility that an optimum value of composition percentage exist

168

Strength and Permeability of Stabilized Peat Soil  

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Full Text Available The aim of this study was to analyze the unconfined compressive strength and initial permeability of peat soil stabilized by a mixture of Ordinary Portland cement, ground granulated blast furnace slag and siliceous sand. An understanding of the stabilized soil properties is of great importance for the design of deep stabilization in peat land for highway construction. Significant evidence on the positive effects of the admixture at stabilizing peat soil was discovered from laboratory testing investigation of the study. Results from the investigation indicated that addition of the admixture was able to increase unconfined compressive strength and reduce initial permeability of the stabilized soil as compared to those of untreated peat.

L.S. Wong

2008-01-01

169

Evaluation of the compressive strength of ancient clay bricks using microdrilling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nondestructive testing techniques are increasingly being used to obtain the geometry of structural and nonstructural elements and hidden features such as voids, cracks, and detachments. However, the evaluation of the compressive strength and other mechanical properties of ancient materials using such techniques remains a challenge. To reliably assess mechanical properties, it is usually necessary to directly test the strength and deformation of materials by destructive methods. To av...

Fernandes, Francisco M.; Lourenc?o, Paulo B.

2007-01-01

170

Determining the Compressive, Flexural and Splitting Tensile Strength of Silica Fume Reinforced Lightweight Foamed Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study investigated the performance of the properties of foamed concrete in replacing volumes of cement of 10%, 15% and 20% by weight. A control unit of foamed concrete mixture made with ordinary Portland cement (OPC) and 10%, 15% and 20% silica fume was prepared. Three mechanical property parameters were studied such as compressive strength, flexural strength and splitting tensile of foamed concrete with different percentages of silica fume. Silica fume is commonly used to increase the m...

Mydin M.A.O; Md, Sani N.; Mohd Yusoff M.A.; Ganesan. S

2014-01-01

171

Compressive And Tensile Strength Of Concrete Loaded And Soaked In Crude Oil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Effect of crude oil on compressive, splitting-tensile, and flexural-tensile strength of concrete under short-term and Lr.^-term loading, were investigated. Results show that the rate of crude oil absorption is high at early stages of soaking, but this rate decreases with time. There is a reduction in the absorption by 30 to 40 percent of ultimate strength in specimens exposed to instantaneous loading as compared with unloaded specimens. While the absorption increases moderately at 70 percent...

Abdul Ahad, Ramzi B.

2000-01-01

172

Using metakaolin to improve the compressive strength and the durability of fly ash based concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Partial replacement of Portland cement by pozzolanic and cimentitious by-products or mineral additions that allow for carbon dioxide emission reductions is a major issue in the current climate change context. However, the use of low pozzolanic activity by-products like fly ash can cause a decrease relatively early in compressive strength. In this paper, the effect of metakaolin and fly ash on strength and concrete durability was investigated. The durability was assessed by different means ...

Torgal, Fernando Pacheco; Shahsavandi, Arman; Jalali, Said

2011-01-01

173

Uniaxial compression tests on diesel contaminated frozen silty soil specimens  

Energy Technology Data Exchange (ETDEWEB)

Results of a uniaxial, unconfined compression test on artificial diesel-contaminated and uncontaminated frozen silty soils are discussed. The testing program involved 59 specimens. The results show that for the same fluid content, diesel contamination reduced the strength of the frozen specimens by increasing the unfrozen water content. For example, in specimens containing 50 per cent diesel oil of the fluid content by weight the maximum strength was reduced by 95 per cent compared to the strength of an uncontaminated specimen. Diesel contamination was also shown to contribute to the slippage between soil particles by acting as a lubricant, thus accelerating the loss of compressive strength.13 refs., 18 figs.

Chenaf, D.; Stampli, N.; Bathurst, R. [Royal Military Coll. of Canada, Kingston, ON (Canada); Chapuis, R.P. [Ecole Polytechnique, Montreal, PQ (Canada)

1999-07-01

174

Uniaxial compression tests on diesel contaminated frozen silty soil specimens  

International Nuclear Information System (INIS)

Results of a uniaxial, unconfined compression test on artificial diesel-contaminated and uncontaminated frozen silty soils are discussed. The testing program involved 59 specimens. The results show that for the same fluid content, diesel contamination reduced the strength of the frozen specimens by increasing the unfrozen water content. For example, in specimens containing 50 per cent diesel oil of the fluid content by weight the maximum strength was reduced by 95 per cent compared to the strength of an uncontaminated specimen. Diesel contamination was also shown to contribute to the slippage between soil particles by acting as a lubricant, thus accelerating the loss of compressive strength.13 refs., 18 figs

175

Effect of Cement Stabilized Kaolin Subgrade on Strength Properties  

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Subgrade performance generally depends on the load bearing capacity of soil. This load is often affected by degree of compaction, moisture content and soil type. Poor subgrade should be avoided by removal, replace and add stabilizer agent to provide a suitable strength for subgrade. This study presents the effect of cement stabilizer on California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) for kaolin clay in low traffic volume road. The test conducted includes determination...

Nur Akmal Abd Karim; Rashid, Ahmad Safuan A.; Norhazilan Md. Noor; Haryati Yaacob

2014-01-01

176

Strength and Permeability of Stabilized Peat Soil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to analyze the unconfined compressive strength and initial permeability of peat soil stabilized by a mixture of Ordinary Portland cement, ground granulated blast furnace slag and siliceous sand. An understanding of the stabilized soil properties is of great importance for the design of deep stabilization in peat land for highway construction. Significant evidence on the positive effects of the admixture at stabilizing peat soil was discovered from laboratory t...

Wong, L. S.; Hashim, R.; Ali, F. H.

2008-01-01

177

Strength Behavior Study of Apples under Compression Loading  

Directory of Open Access Journals (Sweden)

Full Text Available The mechanical properties data of fruits are important in the design of various handling, packing, storage and transportation systems. In this research some mechanical properties of two Iranian apple varieties (Golab Kohanz and Shafi Abadi were analyzed in moisture contents 86% and 84% (W.b for Golab Kohanz and Shafi Abadi varieties, respectively. Mechanical properties including rupture force and energy, deformation to rupture point, failure stress and strain, Young’s modulus (initial tangent modulus, secant modulus, tangent modulus and chard modulus, toughness and hardness were studied under compression loading using standard methods and so firmness was determined by puncture test. Average values of rupture force and energy, failure stress, failure strain, deformation, toughness and hardness were determined,57.81N, 285.88 mJ, 0.37 MPa, 31.2%, 7.77 mm,  0.06 J/cm3, 9.14 N/mm for Shafi Abadi variety, respectively. The corresponding values for Golab Kohanz variety were obtained 51.11 N, 157.51 mJ, 0.32 MPa, 23.36%, 5.6 mm, 0.04 J/cm3 and 7.79 N/mm, respectively. Initial tangent modulus, secant modulus, tangent modulus and chard modulus were obtained 0.93, 1.76, 2.27 and 2.11 MPa for Shafi Abadi variety and 0.81, 1.52, 2.08 and 2.04 MPa for Golab Kohanz variety, respectively. The firmness obtained 59.26 N for Shafi Abadi variety and corresponding value was 47.69 N for Golab Kohanz variety, respectively. According to results Shafi Abadi variety had stiffer and resisterer issue to mechanical forces than Golab Kohanz variety.

Abbas Gorji Chakespari

2010-06-01

178

Strength and Compressibility Characteristics of Reconstituted Organic Soil at Khulna Region of Bangladesh  

Directory of Open Access Journals (Sweden)

Full Text Available This study depicts the experimental investigations into the effect of organic content on the shear strength and compressibility parameters of reconstituted soil. To these attempts, disturbed soil samples were collected from two selected locations of Khulna region. The reconstituted soil having organic content of 5-35 % were prepared in the laboratory to mix at various proportions of inorganic and organic soil at the water content equal to 1.25 times of liquid limits of collected samples .The usual procedure of preparation of soil slurry, deposition in a mold and application of surcharge were used to reconstitute sample. The mold diameter was 152 mm and height 222 mm and applied ultimate surcharge was about 60kN/m2. In the laboratory, ASTM (2004 methods were followed for the determination of strength properties and compressibility parameters of reconstituted soil at varying organic content. Here, it can be depicted that organic content significantly influence the shear strength and compressibility parameters of reconstituted soils. Moreover, some important correlations were developed based on strength and compressibility parameters and organic content which can be expressed by equations that may be proposed to estimate the various properties of soil of Khulna region using its organic content.

Tahia Rabbee

2012-10-01

179

Computative examination of bending strength of girders originally curved and subjected to longitudinal compression  

Science.gov (United States)

This report examines the stipulation contained in the 1918 BLV, that a girder subjected to longitudinal compression under the influence of half of the specified breaking load, along with Euler bending safety with an initial deflection of 1/200 of the length of the girder can, at most, be subjected to half the stipulated breaking strength.

Hoff, Wilhelm

1922-01-01

180

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

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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.

O. Alake

2009-01-01

 
 
 
 
181

Strength and Ductility of Randomly Distributed Palm Fibers Reinforced Silty-Sand Soils  

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This paper investigates the resultant strength and ductility behavior when randomly distributed palm fibers are used to reinforce silty-sand soils. The composite soils were tested under laboratory conditions and examined for unconfined compression strength (UCS), California Bearing Ratio (CBR) and compaction test. The results indicated that; the maximum and residual strengths, orientation of surface failures, ductility and the stress-strain relationship of the specimens were substantially aff...

Marandi, S. M.; Bagheripour, M. H.; Rahgozar, R.; Zare, H.

2008-01-01

182

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

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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.

Akaninyene Afangide Umoh

2012-11-01

183

Statistical analysis of compositional factors affecting the compressive strength of alumina-loaded epoxy (ALOX).  

Energy Technology Data Exchange (ETDEWEB)

Detailed statistical analysis of the experimental data from testing of alumina-loaded epoxy (ALOX) composites was conducted to better understand influences of the selected compositional properties on the compressive strength of these ALOX composites. Analysis of variance (ANOVA) for different models with different sets of parameters identified the optimal statistical model as, y{sub l} = -150.71 + 29.72T{sub l} + 204.71D{sub l} + 160.93S{sub 1l} + 90.41S{sub 2l}-20.366T{sub l}S{sub 2l}-137.85D{sub l}S{sub 1l}-90.08D{sub l}S{sub 2l} where y{sub l} is the predicted compressive strength, T{sub l} is the powder type, D{sub l} is the density as the covariate for powder volume concentration, and S{sub il}(i=1,2) is the strain rate. Based on the optimal statistical model, we conclude that the compressive strength of the ALOX composite is significantly influenced by the three main factors examined: powder type, density, and strain rate. We also found that the compressive strength of the ALOX composite is significantly influenced by interactions between the powder type and the strain rate and between the powder volume concentration and the strain rate. However, the interaction between the powder type and the powder volume concentration may not significantly influence the compressive strength of the ALOX composite.

Montgomery, Stephen Tedford; Ahn, Sung K. (Washington State University, Pullman, WA); Lee, Moo Yul

2006-02-01

184

Optimum Compressive Strength of Hardened Sandcrete Building Blocks with Steel Chips  

Directory of Open Access Journals (Sweden)

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 proofing agent like bitumen and cement containing waterproofing agents be used in the manufacture, laying, and rendering of steel chip sandcrete blocks.

Alohan Omoregie

2013-02-01

185

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

International Nuclear Information System (INIS)

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 < 0.001) between the microhybrid 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. (paper)

186

Residual strength of composite laminates subjected to tensile-compressive fatigue loading  

Science.gov (United States)

Results are presented on the measurements of the residual strengths of T300/934 graphite epoxy laminates, in tension and in compression, after the samples were exposed to tension-compression fatigue loading (R = -1). Four laminate ocnfigurations were tested: unidirectional, cross-ply, angle-ply, and quasi-isotropic. It was found that the fatigue behavior of laminates was dependent on the quasi-static strengths and the specific structure of the laminate. No direct correlation was found between remaining residual strengths and the percentage of average fatigue life. However, a correlation scheme was developed for the individual specimen under test, based on a cumulative damage model and a stiffness change of the material.

Rotem, Assa; Nelson, H. G.

1990-01-01

187

THE COMPRESSIVE AND FLEXURAL STRENGTHS OF SELF-COMPACTING CONCRETE USING RAW RICE HUSK ASH  

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Full Text Available This study investigates the compressive and flexural strengths of self-compacting concrete incorporating raw rice husk ash, individually and in combination with other types of mineral additives, as partial cement replacement. The additives paired with raw rice husk ash were fine limestone powder, pulverized fuel ash and silica fumes. The mix design was based on the rational method where solid constituents were fixed while water and superplasticizer contents were adjusted to produce optimum viscosity and flowability. All mixes were designed to achieve SF1 class slump-flow with conformity criteria ? 520 mm and ? 700 mm. Test results show that 15% replacement of cement using raw rice husk ash produced grade 40 concrete. It was also revealed that 30% and 45% cement replacements using raw rice husk ash combined with limestone powder and raw rice husk ash combined with limestone powder and silica fume respectively, produced comparable compressive strength to normal concrete and improved flexural strengths.

MD NOR ATAN

2011-12-01

188

Effects of local elastic compression on muscle strength, electromyographic, and mechanomyographic responses in the lower extremity.  

Science.gov (United States)

The purpose of this study was to investigate the effect of elastic compression on muscle strength, electromyographic (EMG), and mechanomyographic (MMG) responses of quadriceps femoris during isometric and isokinetic contractions. Twelve participants performed 5s isometric maximal voluntary contractions (MVC) and 25 consecutive and maximal isokinetic knee extensions at 60 and 300°/s with no (control, CC), medium (MC), and high (HC) compression applied to the muscle. The EMG and MMG signals were collected simultaneously with muscle isometric and isokinetic strength data. The results showed that the elevated compression did not improve peak torque, peak power, average power, total work, and regression of torque in the isometric and isokinetic contractions. However, the root mean squared value of EMG in both HC and MC significantly decreased compared with CC at 60 and 300°/s (p<0.01). Furthermore, the EMG mean power frequency in HC was significantly higher than that in CC at 60°/s (p<0.05) whereas no significant compression effect was found in the MMG mean power frequency. These findings provide preliminary evidence suggesting that the increase in local compression pressure may effectively increase muscle efficiency and this might be beneficial in reducing muscle fatigue during concentric isokinetic muscle contractions. PMID:22100152

Fu, Weijie; Liu, Yu; Zhang, Songning; Xiong, Xiaojie; Wei, Shutao

2012-02-01

189

Analyses of spacer grids compression strength and fuel assemblies structural behavior  

International Nuclear Information System (INIS)

Highlights: • Modeling of a 16 × 16 spacer grid to reproduce compression tests. • Evaluation of spacer grids mechanical behavior. • Modeling of fuel assembly with beam-type finite elements. • Calculation of fuel assembly natural frequencies by considering fuel rods sliding. • A new procedure to correct fuel assembly natural frequencies with weighting factor ?. -- Abstract: In this work, finite-element models were proposed to evaluate the spacer grids compression strength and structural behavior of fuel assemblies, mainly in terms of their natural frequencies. Firstly, a three-dimensional model was developed to provide consistent predictions of 16 × 16-type spacer grids compression strength. Regarding their original geometry and some possible design variations, the models were submitted to compression conditions to calculate the maximum compression force and they were validated for comparison with experimental predictions. Secondly, fuel assembly models were proposed with the aim at to correct its natural frequencies. For that, two distinct three-dimensional finite element approaches for the spacer grids, called total mesh and inner mesh, were adopted, respectively. For each model, the maximum and minimum fuel assembly lateral stiffness was determined. Also, by adopting the correction factor ?, the natural frequencies were corrected by a ?(?) value that was characteristic of each model and compared to experimental results. The procedure used in the present work permitted a good agreement between numerical and experimental natural frequencies results with the total mesh model

190

Compressive strength of structural concrete made with locally available coarse aggregates  

International Nuclear Information System (INIS)

Quality of CA (Coarse Aggregate) is one of the prime factors to control the quality of concrete. But construction industry of Sindh is not very much bothered about the quality of CA in concrete manufacturing. In Sindh, Hyderabad vicinity is comparatively rich in production of CA. This research is to evaluate the compressive strength of structural concrete made with CA obtained from five different crush plants (Petaro, Parker, Palari, Ghulam Hyder Baloch and Ongar), available in the vicinity of Hyderabad. ln total 360 concrete cubes (150x150x150mm) were manufactured, 72 for each source of CA by keeping 1:2:4 and 1:1.5:3 material ratios. The cubes were manufactured with 0.45 w/c (water cement ratio), 0.5 and 0.55 w/c and tested for compressive strength after 3, 7, 14 and 28 days of curing. Results show that performance of CA obtained from all the five crush plants remained in agreement with BS and ACI Code recommendations. Concrete made with CA obtained from Petaro and Parker gave higher early strength than that of others while concrete made with CA obtained from Petaro, Parker together with Palari gave higher 28th day compressive strength. (author)

191

Development of a Strength Prediction Model for “Green” Compressed Stabilised Earthbricks  

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Full Text Available Traditional fired clay bricks are widely used as a fundamental building material in most countries. Availability, low costs and low-skilled labour are main factors that have made the bricks a popular choice. However with rising awareness to reduce carbon footprint and promote sustainable development, earth-making has taken a different path to minimize the environmental impact. Compressed stabilised earthbrick is an example of the alternative building material. Various efforts have been directed to develop these bricks, including the use of different binding agents, raw materials and technology. In conjunction with these progresses, and considering that strength is the primary concern in brick-making, it was conceived that a strength prediction model ought to be established to assist in the bricks’ production, especially in the mix design stage. In collaboration with a local property developer, the Research Centre for Soft Soils (RECESS has embarked on an industrial research project to develop “green” sustainable compressed stabilised earthbricks in situ for a large scale mixed development site. As part of the joint research effort, a series of trial specimens were prepared at different mix ratios using soil samples retrieved from the site. The specimens were next examined with the conventional compressive strength test, coupled with the novel non-destructive S-wave velocity measurement. The test results were then analysed and cross-correlated to establish a strength prediction model for the bricks produced. The charts relating the relevant parameters serve not only as a quick guide to the expected strength, but also provide insights to the behaviour of compressed stabilised material under loading.

Chee-Ming Chan

2010-08-01

192

Comparison of quantitative computed tomography-based measures in predicting vertebral compressive strength.  

Science.gov (United States)

Patient-specific measures derived from quantitative computed tomography (QCT) scans are currently being developed as a clinical tool for vertebral strength prediction. QCT-based measurement techniques vary greatly in structural complexity and generally fall into one of three categories: (1) bone mineral density (BMD), (2) "mechanics of solids" (MOS) models, such as minimum axial rigidity (the product of axial stiffness and vertebral height), or (3) three-dimensional finite element (FE) models. There is no clear consensus as to the relative performance of these measures due to differences in experimental protocols, sample sizes and demographics, and outcome metrics. The goal of this study was to directly compare the performance of QCT-based assessment techniques of varying degrees of structural sophistication in predicting experimental vertebral compressive strength. Eighty-one human thoracic vertebrae (T6-T10) from 44 donors cadavers (F=32, M=12; 85+/-8 years old, max=97 years old, min=54 years old) were QCT scanned and destructively tested in uniaxial compression. The QCT scans were processed to generate FE models and various BMD and MOS measures, including trabecular bone mineral density (tBMD), integral bone mineral density (iBMD), and axial rigidity. Bone mineral density was weakly to moderately predictive of compressive strength (R(2)=0.16 and 0.62 for tBMD and iBMD, respectively). In vitro vertebral strength was strongly correlated with both axial rigidity (R(2)=0.81) and FE strength measurements (R(2)=0.80), and the predictive capabilities of these two metrics were statistically equivalent (p>0.05 for differences between FE and axial rigidity). The results of this study indicate that non-invasive predictive measures of vertebral strength should include some level of structural sophistication, specifically, gross geometric and material property distribution information. For uniaxial compression of isolated vertebrae, which is the current biomechanical testing paradigm for new non-invasive strength assessment techniques, QCT-based FE and axial rigidity measures are equivalent predictors of experimental strength. However, before abandoning the FE method in favor of more simplistic techniques, future work should investigate the performance of the FE method versus MOS measures for more physiologically representative loading conditions, e.g., anterior bending or in situ loading with intervertebral discs intact. PMID:17174619

Buckley, Jenni M; Loo, Kenneth; Motherway, Julie

2007-03-01

193

Column and Plate Compressive Strengths of Aircraft Structural Materials: Extruded 24S-T Aluminum Alloy  

Science.gov (United States)

Column and plate compressive strengths of extruded 24S-T aluminum alloy were determined both within and beyond the elastic range from tests of thin-strip columns and local-instability tests of H-, Z-,and channel-section columns. These tests are part of an extensive research investigation to provide data on the' structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures.

Heimerl, George J.; Roy, J Albert

1945-01-01

194

A study on the compressive strength of thick carbon fibre-epoxy laminates  

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This paper describes an experimental study that examines the effect of specimen size on the axial compressive strength of IM7/8552 carbon fibre/epoxy unidirectional laminates (UD). Laminate gauge length, width and thickness were increased by a scaling factor of 2 and 4 from the baseline specimen size of 10 mm x 10 mm x 2 mm. In all cases, strength decreased as specimen size increased, with a maximum reduction of 45%; no significant changes were observed for the axial modulus. Optical microgra...

Lee, J.; Soutis, C.

2007-01-01

195

Column and Plate Compressive Strengths of Aircraft Structural Martials Extruded 0-1HTA Magnesium Alloy  

Science.gov (United States)

Column and plate compressive strengths of extruded 0-1HTA magnesium alloy were determined both within and beyond the elastic range from tests of flat end H-section columns and from local instability tests of H-, Z-, and channel section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures.

Heimerl, George J; Niles, Donald E

1947-01-01

196

Compressive strength and outgassing characteristics of concrete for large vacuum-system construction  

International Nuclear Information System (INIS)

Concrete enclosures can be used for vacuum-system construction. However, limited information exists on the behavior of concrete in vacuum. For this reason, concrete testing was performed recently at the Los Alamos National Laboratory to obtain data on outgassing and compressive strength of concrete in vacuum. The results of the experimental program will be presented to support the major conclusion that concrete is suitable for high-vacuum systems without degradation of strength and should be considered for large vacuum-system construction

197

Effect of non-standard curing methods on the compressive strength of laterized concrete  

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Thirty concrete mixes of differing water-binder ratio containing 0, 10, 20, 30, 40 and 50 % laterite as a partial replacement for sand were used to prepare laterized concrete specimens for the study of the effect of nonstandard curing methods on the strength of specimen. The effectiveness of a curing method was measured quantitatively as the ratio of the compressive strength of specimen cured using the non-standard method to those cursed using the standard water-curing method specified in the...

Udoeyo, Felix F.; Robert Brooks; Christopher Utam; Philip Udo-Inyang; Ukpong, Eno C.

2010-01-01

198

Influence of Fly Ash on the Compressive Strength of Foamed Concrete at Elevated Temperature  

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Full Text Available Foamed concrete is a lightweight concrete that is widely used in the construction industry recently. This study was carried out to investigate the influence of fly ash as a cement replacement material to the residual compressive strength of foamed concrete subjected to elevated temperature. For this study, the foamed concrete density was fixed at 1300 kg/m3 and the sand-cement ratio and water-cement was set at 1:2 and 0.45, respectively. The samples were prepared and tested at the age of 28 days. Based on the results, it has been found that with 25% inclusion of fly ash, the percentage of compressive strength loss was decreased by 3 – 50%.

Ahmad H.

2014-01-01

199

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

Science.gov (United States)

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.

Ratcliffe, James G.; Jackson, Wade C.

2008-01-01

200

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

Science.gov (United States)

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.

Ratcliffe, James G.; Jackson, Wade C.

2008-01-01

 
 
 
 
201

Impact of Vibration Time on Compressive Strength of Hardened Sandcrete Building Blocks  

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The majority of the sandcrete blocks used in the Nigerian building industry fall short of the minimum specification standards. There is evidence to suggest a wide variation in compressive strength from one block manufacturer to another and also within block samples from a single source. This problem has been attributed to poor quality control and substandard constituent materials. Also very alarming is the ignorance surrounding the usage and engineering properties of some of the widely used f...

Alohan Omoregie

2012-01-01

202

Pozzolanic Properties of Micronized Biomass Silica in Enhancing Compressive Strength and Water Permeability of Concrete  

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Full Text Available Normal 0 7.8 ? 0 2 false false false EN-US ZH-CN X-NONE This study presents the analysis and the benefits from using Micronized Biomass Silica (MBS of rice husk which comprises of high content of silica. MBS was generated from controlled burning of the husk into off-white biomass silica ash and crushing the ash into micronized size. Concrete samples containing various percentages of MBS were tested for workability, compressive strength and also water permeability performances. It was found that the optimum percentage of MBS added to the concrete that lead to good performance of concrete in terms of compressive strength and water permeability was 12%. The compressive strength increased up to 43% when 12% of MBS was added to the concrete after 90 days period. Increasing the content of MBS exceeding the optimum percentage showed inferior performance of the concrete. It indicates that the pozzolanic reaction properties of MBS could improve the compressive strength and water permeability of concrete. /* Style Definitions */ table.MsoNormalTable {mso-style-name:????; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";}

Suraya Hani Adnan

2012-10-01

203

Design and Fabrication of a Compression Strength Testing Machine for Blocks and Clay Bricks  

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This study was carried out to design and fabricate a cost effective and efficient compression strength tester to carter for the needs of stakeholders in the blocks and bricks industries. In carrying out the project work a thorough study of the foreign testers and the requirements of the Nigerian industrial standards, NIS 87:2000 and NIS 74:1976 for blocks and clay bricks respectively was done. Design drawings and calculations were established and the machine was fabricated with well selected ...

Hassan, Abdulkadir Baba; Bukar, Yahaya Ahmed

2009-01-01

204

Effect of mix composition on compressive strength and microstructure of fly ash based geopolymer composites  

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Full Text Available Geopolymer is a class of aluminosilicate binding materials synthesized by thermal activation of solid aluminosilicate base materials such as fly ash, metakaolin, GGBS etc. with an alkali metal hydroxide and silicate solution. These binders are currently attracting widespread attention due to their potential utilization as a high performance, environmental friendly and sustainable alternative to Portland cement. The present paper reports results of an experimental study on development of compressive strength and microstructure of geopolymer paste and mortar specimens prepared by thermal activation of Indian fly ash with sodium hydroxide and sodium silicate solution. The effect of main synthesis parameters such as alkali content(Na2O/Al2O3, silica content (SiO2/Al2O3, water to geopolymer solid ratio and sand to fly ash ratio of geopolymer mixture and processing parameters such as curing time and curing temperature on development of compressive strength and microstructure of fly ash based geopolymer paste and mortar were studied. The compressive strength of 48.20MPa was obtained for geopolymer mixture cured at 850C for 24 hours with alkali content of 0.62 and silica content of 4.0. The mineralogical and microstructure studies on hardened geopolymer performed by means Scanning electron microscope (SEM and X-ray diffraction (XRD, showed formation of a new amorphous alumino-silicate phase such as hydroxysodalite and herschelite influenced development of compressive strength. The results obtained in the current research will be useful for developing of mix design guidelines for commercial exploitation of the new binding material.

Ravindra N. Thakur

2009-06-01

205

Influence of Cementitious Materials and Aggregates Content on Compressive Strength of Palm Kernel Shell Concrete  

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This study reports the effect of cementitious materials, fine and coarse aggregates content on workability and compressive strength of palm kernel shell concrete. Palm kernel shells a by product of the production of palm oil, were used as lightweight aggregates. The following cementitious materials were added: 10% silica fume as additional cementitious material and 5% fly ash as cement replacement on weight of cement. The influence of varying fine aggregate and palm kernel shell content...

Alengaram, U. J.; Jumaat, M. Z.; Mahmud, H.

2008-01-01

206

THE COMPRESSIVE AND FLEXURAL STRENGTHS OF SELF-COMPACTING CONCRETE USING RAW RICE HUSK ASH  

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This study investigates the compressive and flexural strengths of self-compacting concrete incorporating raw rice husk ash, individually and in combination with other types of mineral additives, as partial cement replacement. The additives paired with raw rice husk ash were fine limestone powder, pulverized fuel ash and silica fumes. The mix design was based on the rational method where solid constituents were fixed while water and superplasticizer contents were adjusted to produce optimum vi...

MD NOR ATAN; HANIZAM AWANG

2011-01-01

207

Determination of characteristic compressive strength of self- compacting and vibrated concrete  

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The use of self-compacting concrete is increasing due to the demand of faster work performance and better working conditions. The leadership countries in this field are European, and especially Scandinavian countries. Also Slovenian constructors are using self- compacting concrete where performing mechanical vibrations is difficult or impossibile. The purpose of the present Graduation thesis is to determinate the characteristic compressive strength of self-compacting concrete taking in consid...

Turel, Marko

2006-01-01

208

Effect of compressive prestress on the Young's modulus and strength of isotropic graphite  

International Nuclear Information System (INIS)

It is well known that properties, such as Young's modulus, strength and so on, change when compressive or tensile prestresses are applied to graphite materials at room temperature. It is important from the designer's standpoint in the sense that it should be taken into consideration for the structural design of the graphite components if there is an effect of prestresses at high temperature on the mechanical properties. In this study compressive prestresses were applied to an isotropic fine-grained graphite at room temperature (RT) and high temperature (2010 deg. C). As a result decrease in Young's modulus due to high temperature prestressing was 56% which was much larger than the 6.4% that was due to RT prestressing. This finding was considered to be due primarily to difference in degree of preferred orientation of crystallites in the graphite on the basis of Bacon anisotropy factor (BAF) from X-ray diffraction measurement of the prestressed specimens. Furthermore, high temperature compressive prestressing produced an increase in the strength of the isotropic graphite, although room temperature prestressing produced no such effect. The results obtained here suggest that isotropic graphite which is subjected to high-temperature compressive stress becomes anisotropic. It is concluded that it should be considered in the design stage of the reactors that the anisotropy may change after long term operation of high temperature gas-cooled reactors. (author). 6 refs, 8 figs, 3 tabs

209

Compressive strength of elderly vertebrae is reduced by disc degeneration and additional flexion.  

Science.gov (United States)

Computer tomography (CT)-based finite element (FE) models assess vertebral strength better than dual energy X-ray absorptiometry. Osteoporotic vertebrae are usually loaded via degenerated intervertebral discs (IVD) and potentially at higher risk under forward bending, but the influences of the IVD and loading conditions are generally overlooked. Accordingly, magnetic resonance imaging was performed on 14 lumbar discs to generate FE models for the healthiest and most degenerated specimens. Compression, torsion, bending, flexion and extension conducted experimentally were used to calibrate both models. They were combined with CT-based FE models of 12 lumbar vertebral bodies to evaluate the effect of disc degeneration compared to a loading via endplates embedded in a stiff resin, the usual experimental paradigm. Compression and lifting were simulated, load and damage pattern were evaluated at failure. Adding flexion to the compression (lifting) and higher disc degeneration reduces the failure load (8-14%, 5-7%) and increases damage in the vertebrae. Under both loading scenarios, decreasing the disc height slightly increases the failure load; embedding and degenerated IVD provides respectively the highest and lowest failure load. Embedded vertebrae are more brittle, but failure loads induced via IVDs correlate highly with vertebral strength. In conclusion, osteoporotic vertebrae with degenerated IVDs are consistently weaker-especially under lifting, but clinical assessment of their strength is possible via FE analysis without extensive disc modelling, by extrapolating measures from the embedded situation. PMID:25460926

Maquer, Ghislain; Schwiedrzik, Jakob; Huber, Gerd; Morlock, Michael M; Zysset, Philippe K

2015-02-01

210

Modelling and analysis of compressive strength properties of parboiled paddy and milled rice  

Science.gov (United States)

The present investigation deals with analyzing the compressive strength properties of two varieties (Tarom and Fajr) of parboiled paddy and milled rice including: ultimate stress, modulus of elasticity, rupture force and rupture energy. Combined artificial neural network and genetic algorithm were also applied to model these properties. The parboiled samples were prepared with three soaking temperatures (25, 50 and 75°C) and three steaming times (10, 15 and 20 min). The samples were then dried to final moisture contents of 8, 10 and 12% (w.b.). In general, Tarom variety had higher compressive strength properties for paddy and milled rice than Fajr variety. With increase in steaming time from 10 to 20 min, all mentioned properties increased significantly, whereas these properties were decreased with increasing moisture content from 8 to 12% (w.b.). Coupled artificial neural network and genetic algorithm model with one hidden layer, three inputs (soaking temperature, steaming time and moisture content), was developed to predict the compressive strength properties as model outputs. Results indicated that this model could predict these properties with high correlation and low mean squared error.

Nasirahmadi, Abozar; Abbaspour-Fard, Mohammad H.; Emadi, Bagher; Khazaei, Nasser Behroozi

2014-03-01

211

Compressive strength of concrete using lateritic sand and quarry dust as fine aggregate  

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Full Text Available This paper is part of a study investigating the structural characteristics of concrete using various combinations of lateritic sand and quarry dust as complete replacement for conventional river sand fine aggregate. Samples of concrete (eg. cubes were made using varying contents of laterite and quarry dust as fine aggregate. The quantity of laterite was varied from 0% to 100% against quarry dust at intervals of 25%. The samples were cured for specified periods and tested in the laboratory for compressive strength. Workability tests were earlier carried out to determine the optimum water/cement ratios for three different mixes, namely: 1:1:2, 1:1.5:3 and 1:2:4. It was found that 0.5 water/cement ratio produced higher compressive strengths for 1:1:2 mix, while 0.6 water/cement ratio exhibit better workability for 1:1.5:3 mix proportion. Specifically compressive strength ranged from 17-34.2 N/mm2 for the mixes considered. These results compare favourably with those of conventional concrete. The concrete was found to be suitable for use as structural members for buildings and related structures, where laterite content did not exceed 50%.

Joseph O. Ukpata

2012-01-01

212

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)

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.

Hidayat, Irpan; Siauwantara, Alice

2014-03-01

213

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)

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.

Hidayat Irpan

2014-03-01

214

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

Science.gov (United States)

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.

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

2015-01-01

215

Effect of early mobilisation on grip strength, pinch strength and work of hand muscles in cases of closed diaphyseal fracture radius-ulna treated with dynamic compression plating.  

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AIMS: The purpose of the study was to objectively determine the effects of early mobilisation in terms of grip strength and work of hand muscles in cases of closed diaphyseal fracture radius - ulna treated with dynamic compression plating. SUBJECTS AND METHODS: Fifty normal subjects and Twenty-one patients, (Eleven patients treated with early active and resistive goal directed mobilisation and Ten control group) were assessed for pinch strength and grip strength on Pinch Dynamometer and Jamar...

Solanki P; Mulgaonkar K; Rao S

2000-01-01

216

Standard test method for compressive (crushing) strength of fired whiteware materials  

CERN Document Server

1.1 This test method covers two test procedures (A and B) for the determination of the compressive strength of fired whiteware materials. 1.2 Procedure A is generally applicable to whiteware products of low- to moderately high-strength levels (up to 150 000 psi or 1030 MPa). 1.3 Procedure B is specifically devised for testing of high-strength ceramics (over 100 000 psi or 690 MPa). 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

American Society for Testing and Materials. Philadelphia

1988-01-01

217

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

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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.

Terezinha Jesus Esteves Barata

2008-03-01

218

Correction factors to predict the in-place compressive strength of a self-compacting concrete  

Directory of Open Access Journals (Sweden)

Full Text Available The present study aimed to determine whether certain correction factors used in the in-place prediction of compressive strength with concrete cores are directly applicable to self-consolidating concretes (SCCs. The parameters considered were core diameter, casting direction, core moisture, a number of variables intrinsic to cores, and concrete strength. Factors were also established for converting SCC 15 3 15-cm cubic specimen strength into 30 315-cm cylindrical specimen strength. The findings show that the correction factors recommended in EHE-08 and ACI 214.4R-10 overestimate the in-place compressive strength of the SCC analysed. The factors found for converting cubic into cylindrical specimen strength, in turn, were observed to differ from the values set out in the 2010 Model Code, but to be similar to the EHE-08 code proposals.Este estudio tiene como propósito conocer si algunos factores de corrección que se utilizan para predecir la resistencia a compresión in situ a través de probetas testigo son de directa aplicación en los hormigones autocompactantes (HAC. Dichos factores están relacionados con el diámetro, la dirección de extracción, la humedad y algunas variables intrínsecas del testigo, así como el nivel resistente del hormigón. Además, para el HAC de este estudio se han obtenido los factores que convierten la resistencia de una probeta cúbica de 15 3 15 cm en la de una cilíndrica de 30 3 15 cm. Los resultados muestran que los factores de corrección propuestos por la EHE-08 y la ACI 214.4R-10 sobrevaloran la resistencia a compresión in situ del HAC analizado. Asimismo, se han encontrado diferencias en los factores que convierten la resistencia de la probeta cúbica en la de la cilíndrica según el Código Modelo (2010, pero similitudes según la EHE-08.

Rojas-Henao, L.

2013-12-01

219

Impact of Vibration Time on Compressive Strength of Hardened Sandcrete Building Blocks  

Directory of Open Access Journals (Sweden)

Full Text Available The majority of the sandcrete blocks used in the Nigerian building industry fall short of the minimum specification standards. There is evidence to suggest a wide variation in compressive strength from one block manufacturer to another and also within block samples from a single source. This problem has been attributed to poor quality control and substandard constituent materials. Also very alarming is the ignorance surrounding the usage and engineering properties of some of the widely used fine aggregate deposits. As a way forward, this paper aims to re-establish the impact of vibration time in sandcrete block production using six fine aggregate deposits found within Benin City (Midwestern Nigeria and their various pair combinations. Some of the basic properties like silt content, grading parameters—co-efficient of uniformity (Cu, curvature co-efficient (Cc and the fineness modulus (Fm—of these fine aggregates were established by laboratory means. In addition, the wet and dry compressive strength of these sandcrete blocks made from these sands were established. A total of 1,080 block samples produced under very controlled conditions were used in this investigation. It was revealed that the utility value of sand can be improved when the weaker and commonly used sands were combined with those that are better, more expensive and less frequently used at different vibration periods and ratios. Findings further revealed that sand types and the sand combination approach adopted were very significant to grading parameters and strength; at a much higher vibration time the compressive strength and durability properties were also considerably improved.

Alohan Omoregie

2012-05-01

220

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

 
 
 
 
221

Analysis and Assessment of Strength Development in Compressed FaL-G Blocks  

Science.gov (United States)

Of the several options explored in large scale utilization of fly ash, such as production of blended cements, high volume fly ash cement concretes, fly ash, lime and gypsum (FaL-G) combinations, alkali activated fly ash mortars and concretes are of recent innovations. The last two are non-traditional cementing materials, since no cement is used in processing of these materials. This investigation deals with analysis and assessment of strength development in compressed FaL-G blocks. FaL-G chemistry provides a strong scientific base for understanding the mechanisms of interaction. But an equally strong technological base in the production of FaL-G blocks is the need of the hour. In this investigation, analysis has been made to advance a phenomenological model to arrive at the combinations of the ingredients to produce compressed blocks to meet the strength development desired at specified age, based on carefully planned experimental data generated. The analysis of test results has been done within the framework of Abrams' law, which is extensively used in concrete technology. The validity has been examined with an independent set of experimental data. With incorporation of more data covering still wider spectrum of materials the phenomenological model can further be reinforced as a viable tool in the production of compressed FaL-G blocks.

Nagendra Prasad, K.; Vijaya Bhaskar, S.; Narasimhulu, M. L.; Manohara Reddy, R.

2014-09-01

222

Nonhydrostatic compression of gold powder to 60 GPa in a diamond anvil cell: estimation of compressive strength from x-ray diffraction data  

International Nuclear Information System (INIS)

Two gold powder samples, one with average crystallite size of ?30 nm (n-Au) and another with ?120 nm (c-Au), were compressed under nonhydrostatic conditions in a diamond anvil cell to different pressures up to ?60 GPa and the x-ray diffraction patterns recorded. The difference between the axial and radial stress components (a measure of the compressive strength) was estimated from the shifts of the diffraction lines. The maximum micro-stress in the crystallites (another measure of the compressive strength) and grain size (crystallite size) were obtained from analysis of the line-width data. The strengths obtained by the two methods agreed well and increased with increasing pressure. Over the entire pressure range, the strength of n-Au was found to be significantly higher than that of c-Au. The grain sizes of both n-Au and c-Au decreased under pressure. This decrease was much larger than expected from the compressibility effect and was found to be reversible. An equation derived from the dislocation theory that predicts the dependence of strength on the grain size and the shear modulus was used to interpret the strength data. The strength derived from the published grain size versus hardness data agreed well with the present results

223

An Empirical Relationship between Modulus of Elasticity, Modulus of Rupture and Compressive Strength of M60 Concrete Containing Metakaolin  

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Full Text Available This study presents the relationship between modulus of elasticity and, modulus of rupture relationship with compressive strength of M60 concrete incorporating Metakaolin. Comparing the experimentally obtained result with the mechanical properties calculated using the recommended relationship from the various design codes, one finds substantially variation in the data. A new empirical relationship between elastic modulus, modulus of rupture and compressive strength for Metakolin based M60 concrete is proposed.

K. Anbuvelan

2014-09-01

224

Lumbar vertebral body compressive strength evaluated by dual-energy X-ray absorptiometry, quantitative computed tomography, and ashing  

DEFF Research Database (Denmark)

Bone densitometry with DXA (dual energy X-ray absorptiometry) and QCT (quantitative computed tomography) techniques are used for in vivo assessment of bone strength and thereby prediction of fracture risk. However, only few in vitro studies have investigated and compared these techniques' ability to determine vertebral compressive strength. The aim of the present study was to (1) assess the predictive value of DXA, QCT, and pQCT (peripheral QCT) for vertebral bone compressive strength assessed by mechanical testing; (2) describe both linear and power relationship between density and strength; and (3) evaluate whether gender-related differences in the above relations were present. The material comprised human lumbar vertebrae L3 from 51 women and 50 men (age range: 18 to 96 years). The study showed that both DXA and CT techniques (QCT and pQCT) have a high predictive value for vertebral strength. The DXA BMD had a high correlation with maximum compressive load (r2 = 0.86). The QCT and pQCT had high correlations with maximum compressive stress (r2 = 0.75 and r2 = 0.86, respectively). The correlation between ash density of the biomechanically tested specimen and maximum compressive stress was r2 = 0.88. There were no differences between linear and power fit in the degree of determination between density and strength. There was no gender-related difference in the relationship between volumetric density and maximum compressive stress. In conclusion, it was demonstrated that DXA, QCT, and pQCT are ex situ equally capable of predicting vertebral compressive strength with a degree of determination (r2) between 75% and 86%. No differences were found between linear and power analysis of the relationship between density and strength, and no difference was found in the density strength relationship between women and men.

Ebbesen, Ebbe Nils; Thomsen, Jesper Skovhus

1999-01-01

225

A novel dentin bond strength measurement technique using a composite disk in diametral compression.  

Science.gov (United States)

New methods are needed that can predict the clinical failure of dental restorations that primarily rely on dentin bonding. Existing methods have shortcomings, e.g. severe deviation in the actual stress distribution from theory and a large standard deviation in the measured bond strength. We introduce here a novel test specimen by examining an endodontic model for dentin bonding. Specifically, we evaluated the feasibility of using the modified Brazilian disk test to measure the post-dentin interfacial bond strength. Four groups of resin composite disks which contained a slice of dentin with or without an intracanal post in the center were tested under diametral compression until fracture. Advanced nondestructive examination and imaging techniques in the form of acoustic emission (AE) and digital image correlation (DIC) were used innovatively to capture the fracture process in real time. DIC showed strain concentration first appearing at one of the lateral sides of the post-dentin interface. The appearance of the interfacial strain concentration also coincided with the first AE signal detected. Utilizing both the experimental data and finite-element analysis, the bond/tensile strengths were calculated to be: 11.2 MPa (fiber posts), 12.9 MPa (metal posts), 8.9 MPa (direct resin fillings) and 82.6 MPa for dentin. We have thus established the feasibility of using the composite disk in diametral compression to measure the bond strength between intracanal posts and dentin. The new method has the advantages of simpler specimen preparation, no premature failure, more consistent failure mode and smaller variations in the calculated bond strength. PMID:22266033

Huang, Shih-Hao; Lin, Lian-Shan; Rudney, Joel; Jones, Rob; Aparicio, Conrado; Lin, Chun-Pin; Fok, Alex

2012-04-01

226

Improving the compressive strength of bioceramic robocast scaffolds by polymer infiltration.  

Science.gov (United States)

The effect of polymer infiltration on the compressive strength of ?-tricalcium phosphate (TCP) scaffolds fabricated by robocasting (direct write assembly) is analyzed in this work. Porous structures consisting of a tetragonal three-dimensional mesh of interpenetrating rods were fabricated from concentrated TCP inks with suitable viscoelastic properties. Biodegradable polymers (polylactic acid (PLA) and poly(?-caprolactone) (PCL)) were infiltrated into selected scaffolds by immersion of the structure in a polymer melt. Infiltration increased the uniaxial compressive strength of these model scaffolds by a factor of three (PCL) or six (PLA). It also considerably improved the mechanical integrity of the structures after initial cracking, with the infiltrated structure retaining a significant load-bearing capacity after fracture of the ceramic rods. The strength improvement in the infiltrated scaffolds was attributed to two different contributions: the sealing of precursor flaws in the ceramic rod surfaces and the partial transfer of stress to the polymer, as confirmed by finite element analysis. The implications of these results for the mechanical optimization of scaffolds for bone tissue engineering applications are discussed. PMID:20566307

Martínez-Vázquez, Francisco J; Perera, Fidel H; Miranda, Pedro; Pajares, Antonia; Guiberteau, Fernando

2010-11-01

227

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

Directory of Open Access Journals (Sweden)

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.

Ms. Akanksha A. Patil

2014-11-01

228

Dynamics of unconfined spherical flames  

CERN Document Server

Using the soap bubble technique, we visualize the dynamics of unconfined hydrogen-air flames using high speed schlieren video. We show that for sufficiently weak mixtures, i.e., low flame speeds, buoyancy effects become important. Flame balls of a critical dimension begin to rise. The experiments are found in very good agreement with the scaling laws proposed by Zingale and Dursi. We report the results in a fluid dynamics video.

Leblanc, Louis; Dennis, Kadeem; Zhe,; Liang,; Radulescu, Matei I

2012-01-01

229

Compressive strength of esthetic restorative materials polymerized with quartz-tungsten-halogen light and blue LED  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este estudo comparou a resistência à compressão de uma resina composta e de um compômero, fotoativados com luz halógena convencional de quarto-tungstênio (QTH) (XL 300, 3M/SPE) e LED azul (SmartLite PS; Dentsply/De Trey). Foram confeccionados 40 espécimes em forma de disco usando uma matriz bipartid [...] a de politetrafluoretileno (4,0 mm de diâmetro x 8,0 mm de altura) em que o material foi inserido incrementalmente. O tempo de polimerização de cada incremento foi de 40 s para a luz halógena convencional e de 10 s para o LED. Os espécimes foram aleatoriamente alocados em 4 grupos (n=10), de acordo com a fonte de luz e com o material restaurador. Depois de armazenadas em água destilada a 37°C ± 2°C por 24 h, a resistência à compressão dos espécimes foi testada em uma máquina universal de ensaios com célula de carga de 500 kgf a uma velocidade de carregamento de 0,5 mm/min. Os dados (em MPa) foram analisados estatisticamente por ANOVA e teste de Student-Newman-Keuls (p0,05) em sua resistência à compressão quando comparada à fotopolimerização com LED. Contudo, a fotopolimerização do compômero com a luz halógena resultou em uma resistência à compressão significativamente maior que a feita o LED (p>0,05). A resina composta apresentou resistência à compressão significativamente maior que a do compômero, independente da fonte de luz. Concluiu-se que a resistência à compressão dos materiais fotopolimerizados com luz halógena e LED foi influenciada pela densidade de energia empregada e pela composição química dos materiais restauradores estéticos. Abstract in english This study compared the compressive strength of a composite resin and compomer photoactivated with a conventional quartz-tungsten halogen-light (XL 3000, 3M/SPE) and a blue light-emitting diode (LED) (SmartLite PS; Dentsply/De Trey). Forty disc-shaped specimens were prepared using a split polytetraf [...] luoroethylene matrix (4.0 mm diameter x 8.0 mm hight) in which the materials were inserted incrementally. The curing time of each increment was of 40 s with the QTH and 10 s with the LED. The specimens were randomly assigned to 4 groups (n=10), according to the light source and the restorative material. After storage in distilled water at 37oC ± 2oC for 24 h, the specimens was tested in compressive strength in a universal testing machine with load cell of 500 kgf running at a crosshead speed of 0.5 mm/min. Data (in MPa) were analyzed statistically by ANOVA and Student-Newman-Keuls test (p0.05) in the compressive strength when compared to light curing with the LED source. However, light curing of the compomer with the QTH source resulted in significantly higher compressive strength than the use of the LED unit (p>0.05). The composite resin presented significantly higher (p>0.05) compressive strength than the compomer, regardless of the light source. In conclusion, the compressive strength of the tested materials photoactivated with a QTH and a LED light source was influenced by the energy density employed and the chemical composition of the esthetic restorative materials.

Cecy Martins, Silva; Katia Regina Hostilio Cervantes, Dias.

230

Compressive strength and hydration of wastepaper sludge ash-ground granulated blastfurnace slag blended pastes  

International Nuclear Information System (INIS)

Compressive strength and hydration characteristics of wastepaper sludge ash-ground granulated blastfurnace slag (WSA-GGBS) blended pastes were investigated at a water to binder (w/b) ratio of 0.5. The strength results are compared to those of normal Portland cement (PC) paste and relative strengths are reported. Early relative strengths (1 day) of WSA-GGBS pastes were very low but a marked gain in relative strength occurred between 1 and 7 days and this increased further after 28 and 90 days. For the 50% WSA-50% GGBS blended paste, the strength achieved at 90 days was nearly 50% of that of the PC control paste. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric (TG) analysis were carried out to identify the mineral components in the WSA and the hydration products of WSA and WSA-GGBS pastes. The principal crystalline components in the WSA are gehlenite, calcium oxide, bredigite and ?'-C2S (stabilised with Al and Mg) together with small amounts of anorthite and calcium carbonate and traces of calcium hydroxide and quartz. The ?'-C2S and bredigite, which phase separate from liquid phase that forms a glass on cooling, are difficult to distinguish by XRD. The hydration products identified in WSA paste are CH, C4AH13, C3A.0.5CC-bar.0.5CH.H11.5 and C-S-H gel plus possible evidence of small amounts of C2ASH8 and C3A.3CS-bar.H32. Ba3A.3CS-bar.H32. Based upon the findings, a hydration mechanism is presented, and a model is proposed to explain the observed strength development

231

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)

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.

Ahmadian Khoshemehr Leila

2009-09-01

232

Palm fibers influence the compressive strength and CBR on soil cement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Soil cement is a mixture of soil with cement. The usefulness of this mixture is very meaningful to increase the carrying capacity of the land. Weakness that accurs from this mix is the process by cement shrinkage and hydration. This process can lead to cracks and effect the compressive strength and carrying capacity of the soil cement. With the addition of fiber in this mix can reduce or even eliminate the process of shrinkage and hydration. Natural fibers as a mixture of palm fib...

Suroso, P.; Samang, L.; Tjaronge, W.; Ramli, M.

2013-01-01

233

Studies on Compressive Strength Of Ternary Blended Concretes At Different Water Binder Ratios  

Directory of Open Access Journals (Sweden)

Full Text Available The Present experimental investigation is carried out in the optimisation of a Ternary Blended Cementitious system based on Ordinary Portland Cement (OPC/ Fly Ash / Micro Silica for the development of high- performance concrete. Compressive Strength of Ternary Blended Concrete at the ages of 28, 90, 180 days for various combinations of Fly Ash and Micro Silica mixes were investigated. Fly Ash was replaced by 0%, 15% and 20% along with Micro Silica of 0%, 5%, and 10%. All the mixes were studied at three water binder ratios of 0.55, 0.45 and 0.35.

D.Audinarayana

2013-09-01

234

Compressive strength at high temperatures of a concrete made with recycled tire textile and steel fibers  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the results of a research work on the evaluation of the compressive strength at high temperatures of a concrete made with recycled tire steel and textile fibers. It was considered five different concrete compositions, with a water/cement ratio (W/C = 0.43, differ only in the type and amount of fibers. The compositions with smaller amounts of textile fibers were those that gave better results. The compositions with steel fibers showed a less explosive rupture showing the effectiveness of this type of fibers in the spalling and cracking control.

Santos Cristina Calmeiro

2013-09-01

235

Influence of Fly Ash on the Compressive Strength of Foamed Concrete at Elevated Temperature  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Foamed concrete is a lightweight concrete that is widely used in the construction industry recently. This study was carried out to investigate the influence of fly ash as a cement replacement material to the residual compressive strength of foamed concrete subjected to elevated temperature. For this study, the foamed concrete density was fixed at 1300 kg/m3 and the sand-cement ratio and water-cement was set at 1:2 and 0.45, respectively. The samples were prepared and tested at the age of 28 d...

Ahmad H.; Wahid N.; Rahman M.F.A.; Karim N.A.

2014-01-01

236

Investigations on the ultimate compressive strength of composite plates with geometrical imperfections  

DEFF Research Database (Denmark)

A series of studies has been performed within the MARSTRUCT Network of Excellence on Marine Structures in order to investigate the buckling response of glass fibre reinforced polymer plates. These studies include the fabrication, testing and finite element analysis of a large number of plates with initial geometric imperfections. This paper presents the validation of finite element models against a series of plate tests that were performed within this framework and parametric studies that were carried out to identify the effects of geometric imperfections on the ultimate compressive strength of composite plates with three alternative lay-up configurations.

Misirlis, K. Newcastle University

2009-01-01

237

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

International Nuclear Information System (INIS)

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.

238

Compressive strength at high temperatures of a concrete made with recycled tire textile and steel fibers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the results of a research work on the evaluation of the compressive strength at high temperatures of a concrete made with recycled tire steel and textile fibers. It was considered five different concrete compositions, with a water/cement ratio (W/C = 0.43), differ only in the type and amount of fibers. The compositions with smaller amounts of textile fibers were those that gave better results. The compositions with steel fibers showed a less explosive rupture showing the e...

Santos Cristina Calmeiro; Rodrigues João Paulo C.

2013-01-01

239

Compressive strength and compressive fatigue limit of conventional and high viscosity posterior resin composites Resistência a compressão e limite de fadiga compressiva de resinas compostas convencional e de alta viscosidade para dentes posteriores  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this study was to compare the compressive strengths and compressive fatigue limits of three posterior composite resins (Filtek P-60, Surefil and Prodigy Condensable) and a universal restorative composite (Z-100). Cylindrical specimens (8 mm in length x 4 mm in diameter) were used. The dynamic test was performed using the staircase method, and the ratio between compressive fatigue limit and compressive resistance was also calculated (n = 15). The compressive strength and compres...

Letícia Brandão; Gelson Luis Adabo; Luís Geraldo Vaz; José Roberto Cury Saad

2005-01-01

240

Optimum mass-strength analysis for orthotropic ring-stiffened cylinders under axial compression  

Science.gov (United States)

An analysis was developed to calculate the minimum mass-strength curve for an orthotropic cylinder subjected to axial compressive loading. The analysis, which includes the effects of ring and stringer eccentricities, is in a general form so that various cylinder wall and stiffener geometries can be considered. Several different ring-stiffened orthotropic configurations were studied. The minimum mass-strength curves and the dimensions associated with these curves are presented for (in order of decreasing efficiency) a tubular double bead, a nonsymmetric double bead, a Z-stiffened skin, and a trapezoidal corrugation. A comparison of efficiencies of the configurations shows a tubular element cylinder to be more efficient than a 3-percent core-density honeycomb-sandwich cylinder. It was found that for an optimized Z-stiffened skin, the location of the Z-stiffeners (internal or external) made a negligible difference in efficiency.

Shideler, J. L.; Anderson, M. S.; Jackson, L. R.

1972-01-01

 
 
 
 
241

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)

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.

Rolando, A.

2006-09-01

242

Effect of non-standard curing methods on the compressive strength of laterized concrete  

Directory of Open Access Journals (Sweden)

Full Text Available Thirty concrete mixes of differing water-binder ratio containing 0, 10, 20, 30, 40 and 50 % laterite as a partial replacement for sand were used to prepare laterized concrete specimens for the study of the effect of nonstandard curing methods on the strength of specimen. The effectiveness of a curing method was measured quantitatively as the ratio of the compressive strength of specimen cured using the non-standard method to those cursed using the standard water-curing method specified in the BS1881: Part 3:1970 (control. The results of the investigation show that with continuous wetting of the nonstandard curing media by sprinkling with water, the strength of the concrete obtained could be comparable to those cured using the control method. Of the four nonstandard curing methods considered in the study it was observed that the strength of sand- and sawdust-cured specimen were in some instances the same as or higher than those of the standard cured specimens at early age (7days. Although at later age (28 days there were significant differences between the strength of specimens cured using the nonstandard methods and those of corresponding laterite content and water-binder ratio cured using the control method as established by t-test, the designed strength of 20 MPa was attained by all specimens cured using the nonstandard methods, which is indicative that these nonstandard methods could be used as alternative to the standard water curing, especially in situations where much water may not be available for curing specimens.

Felix F. Udoeyo

2010-02-01

243

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

Directory of Open Access Journals (Sweden)

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 (? ? 0.5 on the compressive strength of the VA-blended cement laterized concrete.

Babafemi A.J.

2012-01-01

244

Dynamic shear strength of improved soil with B-type blast-furnace cement  

International Nuclear Information System (INIS)

It is attempted to apply the improved soil using cement materials as the hardening agent to the foundation ground of the important buildings for electric power plants. The current design procedure of the improved ground is based on the static strength such as the unconfined compressive strength of the improved soil. However, it is not clear whether the static strength is relevant to seismic designs where the effects of the cyclic loading induced by the earthquake shall be considered. Hence, the authors studied the dynamic strength of the improved soil in comparison with the static strength, by executing a series of the cyclic triaxial tests with different loading frequencies and the consolidated-undrained triaxial compression tests (CUB tests) with different axial strain rates. The tested soil specimens which have the unconfined compressive strength of about 5 MPa were made in laboratory using the mixture of a dredged marine clayey soil, a B-type blast-furnace cement (300 kg/m3) and water. Both of the CUB tests and the cyclic triaxial tests showed similar results with respect to the relationships between the strength and the strain rate. The larger the compressive strain rate was, the higher the strength became. It is concluded that the static strength could be used as a sufficiently safe value in seismic designs since the strain rate of the cyclic loading induced by the earthquake is much larger than that of the static test. (author)atic test. (author)

245

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

246

In vitro comparison of DE-QCT parameters with the compressive strength of cancellous bone  

International Nuclear Information System (INIS)

Quantitative computed tomography (QCT) is used as a method for assessing bone mineral in patients with osteoporosis. The implication being that if the mass of bone mineral is low enough then the patient is at risk for developing symptoms, i.e., fracture. The authors performed an in vitro test which compared dual-energy-QCT (DE-QCT) parameters with compressive strength. The bone samples were placed in a water bath and CT scanned using a Siemens DR-3. Alternating x-ray pulses of 125 and 85 kVp were used to generate the dual energy images. Four images, high kVp, low kVp, monoenergenic, and calcium equivalent, were reconstructed from each scan. A specially constructed bone mineral calibration phantom, consisting of a polyethylene rod and varying tubes of K2HP04, was placed within the water bath along with the specimens. Comparisons will be made between the various DE parameters and their relationship to the compressive strength of cancellous bone. The critical effect of trabecular bone orientation will also be discussed

247

Effect of fly ash fineness on compressive strength and pore size of blended cement paste  

Energy Technology Data Exchange (ETDEWEB)

This paper presents an experimental investigation on the effect of fly ash fineness on compressive strength, porosity, and pore size distribution of hardened cement pastes. Class F fly ash with two fineness, an original fly ash and a classified fly ash, with median particle size of 19.1 and 6.4 {mu}m respectively were used to partially replace portland cement at 0%, 20%, and 40% by weight. The water to binder ratio (w/b) of 0.35 was used for all the blended cement paste mixes. Test results indicated that the blended cement paste with classified fly ash produced paste with higher compressive strength than that with original fly ash. The porosity and pore size of blended cement paste was significantly affected by the replacement of fly ash and its fineness. The replacement of Portland cement by original fly ash increased the porosity but decreased the average pore size of the paste. The measured gel porosity (5.7-10 nm) increased with an increase in the fly ash content. The incorporation of classified fly ash decreased the porosity and average pore size of the paste as compared to that with ordinary fly ash. The total porosity and capillary pores decreased while the gel pore increased as a result of the addition of finer fly ash at all replacement levels.

Prinya Chindaprasirt; Chai Jaturapitakkul; Theerawat Sinsiri [Khon Kaen University, Khon Kaen (Thailand). Department of Civil Engineering

2005-04-01

248

Increasing the compressive strength of Portland cement concrete using flat glass powder  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 abovementioned 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.

Edson Jansen Pedrosa de, Miranda Júnior; Helton de Jesus Costa Leite, Bezerra; Flávio Salgado, Politi; Antônio Ernandes Macêdo, Paiva.

249

Compressive strength and microstructural characteristics of class C fly ash geopolymer  

Energy Technology Data Exchange (ETDEWEB)

Geopolymers prepared from a class C fly ash (CFA) and a mixed alkali activator of sodium hydroxide and sodium silicate solution were investigated. A high compressive strength was obtained when the modulus of the activator viz., molar ratio of SiO{sub 2}/Na{sub 2}O was 1.5, and the proper content of this activator as evaluated by the mass proportion of Na{sub 2}O to CFA was 10%. The compressive strength of these samples was 63.4 MPa when they were cured at 75{sup o}C for 8 h followed by curing at 23{sup o}C for 28 d. In FTIR spectroscopy, the main peaks at 1036 and 1400 cm{sup -1} have been attributed to asymmetric stretching of Al-O/Si-O bonds, while those at 747 cm{sup -1} are due to the Si-O-Si/Si-O-Al bending band. The main geopolymeric gel and calcium silicate hydrate (C-S-H) gel co-exist and bond some remaining unreacted CFA spheres as observed in XRD and SEM-EXDA. The presence of gismondine (zeolite) was also observed in the XRD pattern.

Xiaolu Guo; Huisheng Shi; Warren A. Dick [Key Laboratory of Advanced Civil Engineering Materials (Tongji University), Shanghai (China)

2010-02-15

250

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

Science.gov (United States)

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.

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

1996-01-01

251

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

Science.gov (United States)

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 dimensions. To determine fractal dimensions of more than hundred andesite blocks in cores, a computer program namely FRACRUN were developed. Fractal geometry has been used as practical and popular tool to define particularly irregular shaped bodies in literature since the theory of fractal was developed by Mandelbrot (1967) (Hyslip and Vallejo, 1997; Kruhl and Nega, 1996; Bagde etal., 2002; Gulbin and Evangulova, 2003; Pardini, 2003; Kolay and Kayabali, 2006; Hamdi, 2008; Zorlu, 2009 and Sezer, 2009). Although there are some methods to determine fractal dimensions, square grid-cell count method for 2D and segment count method for 1D were followed in the algorithm of FRACRUN. FRACRUN has capable of determine fractal dimensions of many closed polygons on a single surface. In the study, a database composed of uniaxial compressive strength, volumetric block proportion, fractal dimensions and number of blocks for each core was established. Finally, prediction models were developed by regression analyses and compared with the empirical equations proposed by Sonmez et al. (2006). Acknowledgement This study is a product of ongoing project supported by TUBITAK (The Scientific and Technological Research Council of Turkey - Project No: 108Y002). References Bagde, M.N., Raina, A.K., Chakraborty, A.K., Jethwa, J.L., 2002. Rock mass characterization by fractal dimension. Engineering Geology 63, 141-155. Gokceoglu, C., 2002. A fuzzy triangular chart to predict the uniaxial compressive strength of the Ankara agglomerates from their petrographic composition. Engineering Geology, 66 (1-2), 39-51. Gulbin, Y.L., Evangulova, E.B., 2003. Morphometry of quartz aggregates in granites: fractal images referring to nucleation and growth processes. Mathematical Geology 35 (7), 819-833 Hamdi, E., 2008. A fractal description of simulated 3D discontinuity networks. Rock Mechanics and Rock Engineering 41, 587-599. Hyslip, J.P., Vallejo, L.E., 1997. Fractals analysis of the roughness and size distribution of granular materials. Engineering Geology 48, 231-244. Kahraman, S., Alber, M., Fener, M. and Gu

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

2010-05-01

252

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

Science.gov (United States)

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.

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

2010-01-01

253

Improvement compressive strength of concrete in different curing media by Al2O3 nanoparticles  

International Nuclear Information System (INIS)

Research highlights: ? Al2O3 nanoparticles. ? Mechanical properties. ? Physical properties. ? Thermal properties. ? Microstructure. - Abstract: In the present work, the effect of curing medium on microstructure together with physical, mechanical and thermal properties of concrete containing Al2O3 nanoparticles has been investigated. Portland cement was partially replaced by Al2O3 nanoparticles with the average particle size of 15 nm and the specimens were cured in water and saturated limewater for specific ages. The results indicate that Al2O3 nanoparticles up to maximum of 2.0% produces concrete with improved compressive strength and setting time when the specimens cured in saturated limewater. The optimum level of replacement for cured specimens in water is 1.0 wt%. Although the limewater reduces the strength of concrete without nanoparticles when it is compared with the specimens cured in water, curing the specimens bearing nanoparticles in saturated limewater results in more strengthening gel formation around Al2O3 nanoparticles causes more rapid setting time together with high strength. 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 Al2O3 nanoparticles cub>O3 nanoparticles could improve mechanical and physical properties of the specimens.

254

Ultimate tensile strength testing campaign on ITER pre-compression ring mock-ups  

Energy Technology Data Exchange (ETDEWEB)

ENEA has developed and characterized a high strength glass fibre-epoxy composite as reference material for the manufacture of the two sets of 3 pre-compression rings located at top and bottom of the inner straight leg region of the ITER Toroidal Field (TF) coils. These rings will provide a radial force of about 70 MN/coil at cryogenic temperature pulling the TF coils into contact and reducing toroidal tension in the four outer intercoil structures. The paper describes the ultimate tensile strength (UTS) testing campaign carried out at ENEA Frascati laboratories on six different rings manufactured winding S2 glass fibers on a diameter of 1 m (1/5 of the full scale) by both vacuum pressure epoxy impregnation and filament wet winding techniques. The volumetric glass content was around 70%. The rings were expanded with radial steps of 0.1 mm into a dedicated hydraulic testing machine consisting of 18 radial actuators working in position control with a total capability of 1000 tons. All the mock-ups showed very high tensile strength (1550 MPa is the average of the mean hoop stresses at failure) and a practically constant tensile modulus. The test results are reported and discussed.

Rossi, Paolo, E-mail: paolo.rossi@enea.it [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65, 00044 Frascati (Rome) (Italy); Capobianchi, Mario; Crescenzi, Fabio; Massimi, Alberto; Mugnaini, Giampiero; Nardi, Claudio; Pizzuto, Aldo [Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, C.P. 65, 00044 Frascati (Rome) (Italy); Bettinali, Livio [Consorzio CREATE, Via Claudio 21, 80125 Napoli (Italy); Knaster, Juan [ITER, Route de Vinon-sur-Verdon CS 90 046, 13067, St. Paul-lez-Durance Cedex (France); Rajainmaki, Hannu [FUSION FOR ENERGY, Josep Pla no 2, Torres Diagonal Litoral Edificio B3, 08019 Barcelona (Spain); Evans, David [Advanced Cryogenic Materials, Abingdon, Oxon (United Kingdom)

2011-10-15

255

Effect of water curing conditions on the hydration degree and compressive strengths of fly ash-cement paste  

Energy Technology Data Exchange (ETDEWEB)

This paper explains the effect of water curing condition on compressive strengths of fly ash-cement paste by quantitative data of hydration degree. Hydration of fly ash-cement paste was estimated by Rietveld analysis and selective dissolution. The result shows that the hydration degree of belite is affected by water curing conditions, more so than that of fly ash and alite. Fly ash still continues to hydrate even without an extra, external supply of water. The strong dependence of fly ash-cement concrete on curing conditions does not come from the hydration degree of fly ash, but rather comes from the hydration degree of cement, especially belite. When the water to binder ratio is low enough, the hydration of cement plus small hydration of fly ash are considered to be enough for adequate compressive strength at the beginning. Then, compressive strength of fly ash-cement paste becomes less sensitive to the water curing period.

Pipat Termkhajornkit; Toyoharu Nawa; Kiyofumi Kurumisawa [Hokkaido University, Sapporo (Japan). Division of Environment and Resources Engineering, Graduate School of Engineering

2006-10-15

256

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

Directory of Open Access Journals (Sweden)

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.

Waldemir Rodrigues

2004-06-01

257

Dynamic shear strength of S2 glass fiber reinforced polymer composites under shock compression  

Science.gov (United States)

In the present paper, a series of plate impact shock-reshock and shock-release experiments were conducted to study the critical shear strength of a S2 glass fiber reinforced polymer (GRP) composite under shock compression levels ranging from 0.8 to 1.8 GPa. The GRP was fabricated at ARL, Aberdeen, using S2 glass woven roving in a Cycom 4102 polyester resin matrix. The experiments were conducted by using an 82.5 mm bore single-stage gas gun at Case Western Reserve University. In order to conduct shock-reshock and shock-release experiments a dual flyer plate assembly was utilized. The shock-reshock experiments were conducted by using a projectile faced with GRP and backed with a relatively high shock impedance Al 6061-T6 plate; while for the shock-release experiments the GRP was backed by a relatively lower impedance polymethyl methacrylate backup flyer plate. A multibeam velocity interferometer was used to measure the particle velocity profile at the rear surface of the target plate. By using self-consistent technique procedure described by Asay and Chabbildas [Shock Waves and High-Strain-Rate Phenomena, in Metals, edited by M. M. Myers and L. E. Murr (Plenum, New York, 1981), pp. 417-431], the critical shear strength of the GRP (2?c) was determined for impact stresses in the range of 0.8 to 1.8 GPa. The results show that the critical shear strength of the GRP is increased from 0.108 GPa to 0.682 GPa when the impact stress is increased from 0.8 to 1.8 GPa. The increase in critical shear strength may be attributed to rate-dependence and/or pressure dependent yield behavior of the GRP.

Yuan, Fuping; Tsai, Liren; Prakash, Vikas; Dandekar, Dattatraya P.; Rajendran, A. M.

2008-05-01

258

Compressive yield strength of the nanocrystalline Cu with Al2O3 dispersoid  

International Nuclear Information System (INIS)

Research highlights: ? 0.2% yield stress of the HPed nc-Cu with the 4 vol.% of the Al2O3 dispersoids is as high as 863 MPa ? The major contribution to total yield strength of the nc-Cu (25.5 nm) with Al2O3 (4 nm, 4 vol.%) dispersoid is attributed to the grain size of the Cu. - Abstract: Nanocrystalline (nc) Cu with Al2O3 dispersoid (?4 vol.%) was successfully synthesized by simple cryo-milling at 210 K with a mixture of Cu2O, Al, and Cu elemental powders. The milled powder was consolidated by hot pressing (HP) at 1123 K and 50 MPa for 2 h. TEM (Transmission Electron Microscopy) work revealed that both of the milled powder and the hot pressed (HPed) materials were comprised with a mixture of the nc-Cu and homogeneous distribution of Al2O3 dispersoids. The compressive and micro Vickers hardness tests were performed on the HPed materials (nanocrystalline Cu with 4 vol.% of Al2O3 dispersoid) at room temperature to characterize the mechanical properties of the materials. The compressive yield strength of the materials was as high as 863 MPa; the micro Vickers hardness 2600 MPa. The results of the mechanical tests apparently show that the relationship between the yield strength and the micro hardness of the HPed materials is in well agreement with Tabor's rule, Hv = 3?y in MPa. The grain size of the nc-Cu was estimated by XRD of the nc-Cu was estimated by XRD using Scherrer's formula and TEM observation; the Al2O3 dispersoid size was measured from element mapping by STEM-EDS (Scanning Transmission Electron Microscopy-Energy Dispersive Spectroscopy) works. An attempt was made to quantify the possible strengthening effects of the nc-Cu materials with Al2O3 dispersoid. Two strengthening mechanisms were proposed for high hardness and yield strength of the materials, i.e., grain size and dispersion hardening effects.

259

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

Science.gov (United States)

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.

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

2014-01-01

260

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

Science.gov (United States)

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. PMID:25531006

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

2014-01-01

 
 
 
 
261

Hot/Wet Open Hole Compression Strength of Carbon/Epoxy Laminates for Launch Vehicle Applications  

Science.gov (United States)

This Technical Memorandum examines the effects of heat and absorbed moisture on the open hole compression strength of carbon/epoxy laminates with the material and layup intended for the Ares I composite interstage. The knockdown due to temperature, amount of moisture absorbed, and the interaction between these two are examined. Results show that temperature is much more critical than the amount of moisture absorbed. The environmental knockdown factor was found to be low for this material and layup and thus obtaining a statistically significant number for this value needs to be weighed against a program s cost and schedule since basis values, damage tolerance, and safety factors all contribute much more to the overall knockdown factor.

Nettles, Alan T.

2009-01-01

262

Measurement of sound velocities and shear strength of cerium under shock compression  

International Nuclear Information System (INIS)

Sound velocity in shock-compressed cerium was measured over the pressure range of 35-140 GPa using the rarefaction overtake technique. Indicator liquids carbogal and tetrachloromethane were used. The samples were loaded with planar shock wave generators using powerful high explosives (HE). Luminescence of the liquid indicators was recorded by optical gauges based on photodiode 'FD 256'. For the pressure range of 13-35 GPa, sound velocity was measured in cerium samples using the counter release method with manganin-based piezoresistive gauges. From the measured longitudinal and bulk sound velocities, Poisson's ratio and shear strength of cerium were determined. The melting boundary on the shock Hugoniot was estimated. Experimental data is compared with calculation results

263

A Simplified Method for predicting Ultimate Compressive Strength of Ship Panels  

DEFF Research Database (Denmark)

A simplified method for predicting ultimate compressive strength of ship panels which have complex shape of the initial deflection is described. The procedure consist of the elastic large deflection theory and the rigid-plastic analysis based on the collapse mechanism taking into account large deformation effects. By taking only one component for the selected deflection function, the computer time for the elastic large deflection analysis will be drastically reduced. The validity of the procedure is checked by comparing the present solutions with the finite-element results for actual ship panels with complex shapes of measured initial deflection. It is concluded that the proposed procedure provides quite accurate solutions for the ultimate loads with extremely short computer time.

Paik, Jeom Kee; Pedersen, Preben Terndrup

1996-01-01

264

Predicting the compressive strength of cemented uranium tailings filling body based on adaptive neuron-fuzzy inference system  

International Nuclear Information System (INIS)

A series uniaxial compressive tests were conducted by using an RMT-150B testing system to investigate the effects of slurry concentration, cement-tailings ratio and curing period on compressive strength of uranium tailings filling body, the stress-strain curve of the backfilling body was obtained, and their failure characteristics were analyzed. On the basis of the test results, an adaptive neuron-fuzzy inference system (ANFIS) model for predicting compressive strength is established using the adaptive neuron-fuzzy inference system based on slurry concentration, cement-tailings ratio and curing period. It was found that there is direct proportion relation between the compressive strength and affecting factors such as slurry concentration, cement-tailings ratio and curing period; the failure law of filling body follows the plastic-elastic-plastic failure model; the ANFIS model provides predictions with high accuracy about 94%, which proves to be a new approach for estimation of compressive strength of uranium tailings filling body. (authors)

265

The Effect of Curing Conditions on the Compressive Strength of White Concrete Produced with Various Dosages  

Directory of Open Access Journals (Sweden)

Full Text Available The white cement, which has been used more widely in aesthetic and decorative applications in Turkey and the use of white cement has not widely common yet in constructional applications. In this study white cement, white calcareous aggregate and marble powder are used and produced white concrete. Furthermore, the effect of curing conditions was investigated on the compressive strength behavior of structural elements. For this reason, the performance properties of white concrete with various cement contents in the range of 250-650 kg/m3 were examined experimentally by keeping chemical admixture ratio constantly. The mixtures were produced in ten different proportions with and without chemical admixtures. The concrete mixtures which were prepared and cured in three different curing conditions. Some of the specimens were placed in water at 20 ± 2 oC and some of them were kept in laboratory environment without placing in water (20 ± 2 oC and % 68 RH and the rest of the specimens were kept in nylon cover. In hardened concrete testing, compressive strength test was performed at 7, 28 and 90 days for white concrete specimens. Based on these concrete designs, it can be concluded that by the use of white cement between 250 and 650 kg/m3 it is possible to produce white concrete according to the ready-mixed concrete standard. According to test results, the specimens which were kept in water and prepared with chemical admixtures were performed better performance than the specimens were kept in air and nylon cover and produced without chemical admixtures.

Mücteba Uysal

2011-12-01

266

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 superio [...] r 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.

Antonio, Piratelli-Filho; Frank, Shimabukuro.

2008-12-01

267

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

Directory of Open Access Journals (Sweden)

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.

Antonio Piratelli-Filho

2008-12-01

268

Estimate of compressive strength of an unidirectional composite lamina using cross-ply and angle-ply laminates  

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Full Text Available In this work has been estimated the compressive strength of a unidirectional lamina of a carbon/epoxy composite material, using the cross-ply and angle-ply laminates. Over the years various methods have been developed to deduce compressive properties of composite materials reinforced with long fibres. Each of these methods is characterized by a specific way of applying load to the specimen. The method chosen to perform the compression tests is the Wyoming Combined Loading Compression (CLC Test Method, described in ASTM D 6641 / D 6641M-09. This method presents many advantages, especially: the load application on the specimen (end load combined with shear load, the reproducibility of measurements and the experimental equipment quite simplified. Six different laminates were tested in compressive tests. They were realized by the same unidirectional prepreg, but with different stacking sequences: two cross-ply [0/90]ns, two angle-ply [0/90/±45]ns and two unidirectional laminates [0]ns and [90]ns. The estimate of the compressive strength of the unidirectional laminates at 0°, was done by an indirect analytical method, developed from the classical lamination theory, and which uses a multiplicative parameter known as Back-out Factor (BF. The BF is determined by using the experimental values obtained from compression tests.

M. Scafè

2014-07-01

269

Determining the Compressive, Flexural and Splitting Tensile Strength of Silica Fume Reinforced Lightweight Foamed Concrete  

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Full Text Available This study investigated the performance of the properties of foamed concrete in replacing volumes of cement of 10%, 15% and 20% by weight. A control unit of foamed concrete mixture made with ordinary Portland cement (OPC and 10%, 15% and 20% silica fume was prepared. Three mechanical property parameters were studied such as compressive strength, flexural strength and splitting tensile of foamed concrete with different percentages of silica fume. Silica fume is commonly used to increase the mechanical properties of concrete materials and it is also chosen due to certain economic reasons. The foamed concrete used in this study was cured at a relative humidity of 70% and a temperature of ±28°C. The improvement of mechanical properties was due to a significant densification in the microstructure of the cement paste matrix in the presence of silica fume hybrid supplementary binder as observed from micrographs obtained in the study. The overall results showed that there is a potential to utilize silica fume in foamed concrete, as there was a noticeable enhancement of thermal and mechanical properties with the addition of silica fume.

Mydin M.A.O.

2014-01-01

270

Effects of fabrication and joining processes on compressive strength of boron/aluminum and borsic/aluminum structural panels  

International Nuclear Information System (INIS)

Processes for forming and joining boron/aluminum and borsic/aluminum to themselves and to titanium alloys were studied. Composite skin and titanium skin panels were joined to composite stringers by high strength bolts, by spotwelding, by diffusion bonding, by adhesive bonding, or by brazing. The effects of the fabrication and joining processes on panel compressive strengths were discussed. Predicted buckling loads were compared with experimental data

271

A Comparative Study on Compressive and Flexural Strength of Concrete Containing Different Admixtures as Partial Replacement of Cement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Concrete is the most widely used material in the world today. This paper is about the comparative study of the flexural strength and compressive strength of concrete when different admixtures are used as partial replacement of cement in the concrete mix. The mineral admixtures that are used here are Silica Fume, Rice Husk Ash and Iron slag as partial replacement of cement. All these materials are industrial waste products and are abundantly available nowadays. These materials ...

Apoorv Singh; Patel, Prof R. D.

2014-01-01

272

Compressive and splitting tensile strength of autoclaved aerated concrete (AAC containing perlite aggregate and polypropylene fiber subjected to high temperatures  

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Full Text Available This paper presents the results of an experimental study on the residual compressive and splitting tensile strength ofautoclaved aerated concrete (AAC containing perlite and polypropylene (PP fiber subjected to high temperatures. Cylinderspecimens were subjected to various temperature ranges of 100, 200, 400, 800, and 1,000°C. The mixtures were prepared withAAC cementitious materials containing perlite at 15%, 20%, and 30% sand replacement. The polypropylene fiber content of0, 0.5%, 1%, 1.5%, and 2% by volume was also added to the mixture. The results showed that the unheated compressive andsplitting tensile strength of AACs containing PP fiber were not significantly higher than those containing no PP fiber.Furthermore, the presence of PP fiber was not more effective for residual compressive strength than splitting tensile strength.The 30% perlite replacement of sand gave the highest strength. Based on the results, it can be concluded that addition ofPP fiber did not significantly promote the residual strength of AAC specimens subjected to high temperatures.

Borvorn Israngkura Na Ayudhya

2011-10-01

273

Improvement of compressive strength of segmentation of zeolites as absorber of Sr-90 liquid waste using coconut fibres  

International Nuclear Information System (INIS)

The use of the coconut fibres to increase compressive strength of segmentation of zeolites as absorber of Sr-90 liquid waste was studied. The purpose of this research was to find the optimum content and length of fibres that give maximum compressive strength. This research was done with mortar-zeolites specimen of cylinder 2,2 cm diameter and 4,4 cm high, the content of zeolites was 13% volume of specimen, weight ratio of water and cement 0,3, length of fibres 1,5 cm, 2 cm, 2,5 cm, and 3 cm (aspect ratio ± 60, ± 80, ± 100 and ± 120) with the fibres content of each fibre 0%, 0,5%, 0,10%, 0,25%, 0,50%, 0,75%, and 1,00%. Addition of fibres was done with a direction of orientation longitudinal to the specimen. The specimens were tested on 28 days old test specimens. The result showed that addition of coconut fibres until certain content would increase compressive strength. The optimum size of fibres with 92,313 N/MM2 of compressive strength or increased 119,21% of no fibres specimen were 0,50% of volume and 3 cm in length

274

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

LENUS (Irish Health Repository)

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.

Dowling, Adam H

2012-03-01

275

Improvement of the compressive strength of a cuttlefish bone-derived porous hydroxyapatite scaffold via polycaprolactone coating.  

Science.gov (United States)

Cuttlefish bones (CBs) have emerged as attractive biomaterials because of their porous structure and components that can be converted into hydroxyapatite (HAp) via a hydrothermal reaction. However, their brittleness and low strength restrict their application in bone tissue engineering. Therefore, to improve the compressive strength of the scaffold following hydrothermal conversion to a HAp form of CB (CB-HAp), the scaffold was coated using a polycaprolactone (PCL) polymer at various concentrations. In this study, raw CB was successfully converted into HAp via a hydrothermal reaction. We then evaluated their surface properties and composition by scanning electron microscopy and X-ray diffraction analysis. The CB-HAp coated with PCL showed improved compressive performance and retained a microporous structure. The compressive strength was significantly increased upon coating with 5 and 10% PCL, by 2.09- and 3.30-fold, respectively, as compared with uncoated CB-HAp. However, coating with 10% PCL resulted in a reduction in porosity. Furthermore, an in vitro biological evaluation demonstrated that MG-63 cells adhered well, proliferated and were able to be differentiated on the PCL-coated CB-HAp scaffold, which was noncytotoxic. These results suggest that a simple coating method is useful to improve the compressive strength of CB-HAp for bone tissue engineering applications. PMID:23661509

Kim, Beom-Su; Kang, Hyo Jin; Lee, Jun

2013-10-01

276

Degradation of the compressive strength of unstiffened/stiffened steel plates due to both-sides randomly distributed corrosion wastage  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The paper addresses the problem of the influence of randomly distributed corrosion wastage on the collapse strength and behaviour of unstiffened/stiffened steel plates in longitudinal compression. A series of elastic-plastic large deflection finite element analyses is performed on both-sides randoml [...] y corroded steel plates and stiffened plates. The effects of general corrosion are introduced into the finite element models using a novel random thickness surface model. Buckling strength, post-buckling behaviour, ultimate strength and post-ultimate behaviour of the models are investigated as results of both-sides random corrosion.

Zorareh Hadj, Mohammad; Esmaeil, Nouri; Mohammad Reza, Khedmati; Mohammad Mahdi, Roshanali.

2010-09-01

277

Predictive equations for compressive strength of concrete based on Schmidt hammer rebound and ultrasonic pulse velocity data  

International Nuclear Information System (INIS)

The compressive strength of concrete is assessed to ensure uniformity of the placed concretc and adequacy of thc strcngth. Non-destructive test (NDT) techniques of ultrasonic pulse velocity and Schmidt rebound hammer tests are commonly used to estimate concrete strength, but the applicability is dependent on correlation of the data with the compressive strength of concrete, the equipment calibration and interpretation of the data. Twenty four standard concrcte cubes were cast respectively from 3 concrete mixes, and tested after 28 days of curing by ultrasonic velocity, rebound hammer and crushing tests. The data were analysed by regression methods to obtain equations for predicting the compression strength of concrete based on the ultrasonic pulse velocity and rebound number. Accurate prediction of the strength of concrete was made when the ultrasonic pulse velocity and the rebound hammer data were combined than when used separately, as the standard error was least. Comparison on the calibration curves of the prediction equations with published plots showed very good agreement. (au)

278

Data on Material Properties and Panel Compressive Strength of a Plastic-bonded Material of Glass Cloth and Canvas  

Science.gov (United States)

Results are presented of tests for determining the tensile, compressive, and bending properties of a material of plastic-bonding glass cloth and canvas layers. In addition, 10 panel specimens were tested in compression. Although the material is not satisfactory for primary structural use in aircraft when compared on a strength-weight basis with other materials in common use, there appears to be potential strength in the material that will require research for development. These points are considered in some detail in the concluding discussion of the report. An appendix shows that a higher tensile strength can be obtained by changes in the type of weave used in the glass-cloth reinforcement.

Zender, George W; Schuette, Evan H; Weinberger, Robert A

1944-01-01

279

Studies on the Determination of Compressive Strengths of Different Grades of Rice Husk Ash—An Ecofriendly Concrete  

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Full Text Available Rice Husk Ash (RHA Concrete is an eco friendly concrete and has evolved as an innovative technology, capable of achieving the status of being an outstanding advancement in the sphere of concrete technology. The utilization of Rice Husk Ash (RHA will reduce the dumping of rice husk as well as reduce the construction cost. In this communication investigations for the determination of residual compressive strength of M30 & 40 grades of RHA concretes exposed at different temperatures were carried. Almost all specimens of M30 & 40 grades of RHA concrete and normal concrete exhibited zero strength at a temperature of 1000°C. It shows that concrete cannot withstand a temperature of 1000°C and above. It was also concluded that compressive strength of RHA concrete was higher at °emperature below 500°C and decreases above 500°C.

Patnaikuni Chandan Kumar

2013-04-01

280

A Comparative Study on Compressive and Flexural Strength of Concrete Containing Different Admixtures as Partial Replacement of Cement  

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Full Text Available Concrete is the most widely used material in the world today. This paper is about the comparative study of the flexural strength and compressive strength of concrete when different admixtures are used as partial replacement of cement in the concrete mix. The mineral admixtures that are used here are Silica Fume, Rice Husk Ash and Iron slag as partial replacement of cement. All these materials are industrial waste products and are abundantly available nowadays. These materials have high silica content and pozzolanic properties and can be effectively used as a replacement of cement during the formation of High Performance Concrete. Compressive and Flexural strength are the two most important characteristic of concrete and are calculated for the hardened concrete to analyze the load bearing capacity for design purposes. Thus for the effective judgment of type of mineral admixtures to be used a comparative study is very useful.

Apoorv Singh

2014-09-01

 
 
 
 
281

An effective thickness proposal for strength evaluation of one-side pitted steel plates under uniaxial compression  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english This paper presents the results of an investigation into the post-buckling behaviour and ultimate strength of imperfect pitted steel plates used in ship and other marine-related structures. A series of elastic-plastic large deflection finite element analyses is performed on pitted steel plates. The [...] effects of pitting corrosion on one side of the plates are introduced into the finite element models. The effects on plate compressive strength as a result of parametric variation of the pitting corrosion geometry are evaluated. A proposal on the effective thickness is concluded in order to estimate the ultimate strength and explore the post-buckling behaviour of pitted steel plates under uniaxial compression.

Zorareh Hadj Mohammad Esmaeil, Nouri; Mohammad Reza, Khedmati; Shokoufeh, Sadeghifard.

2012-08-01

282

Modeling particulate self-healing materials and application to uni-axial compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Using an advanced history dependent contact model for DEM simulations, including elasto-plasticity, viscosity, adhesion, and friction, pressure-sintered tablets are formed from primary particles. These tablets are subjected to unconfined uni-axial compression until and beyond failure. For fast and slow deformation we observe ductile-like and brittle softening, respectively. We propose a model for local self-healing that allows damage to heal during loading such that the material strength of t...

Herbst, Olaf; Luding, Stefan

2008-01-01

283

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

Directory of Open Access Journals (Sweden)

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 about 25% larger in men, yield and ultimate strains were quasi equal for sexes, break strains were 10% higher in women. Ultimate energy absorption capacity was 10%–20% higher in men; the final ductile energy absorption capacity was quasi equal for sexes in all levels. Age-dependence was stronger for men, mainly in central regions (ultimate load, male: r = ?0.66, p < 0.01, female: r = ?0.52, p < 0.005; ultimate stress, male: r = ?0.69, p < 0.01, female: r = ?0.50, p < 0.005; Young’s modulus, male: r = ?0.55, p < 0.05, female: r = ?0.52, p < 0.005, ultimate stiffness, male: r = ?0.58, p < 0.05, female: r = ?0.35, p < 0.03, central ultimate absorbed energy density, male: r = ?0.59, p < 0.015, female: r = ?0.29, p < 0.08.Conclusions: For the strongly osteoporotic population (BMD < 0.4 g/cm2, T-score < ?4 the statical variables (loads, stresses showed significant correlation; mixed variables (stiffness, Young’s modulus, energy showed moderate correlation; kinematical variables (displacements, strains showed no correlation with age. The strong correlation of men between BMD and aging (r = ?0.82, p < 0.001 and betwen BMD and strength parameters (r = 0.8–0.9, p < 0.001 indicated linear trends in age-related strength loss for men; however, the moderate correlation of women between BMD and aging (r = ?0.47, p < 0.005 and between BMD and strength parameters (r = 0.4–0.5, p < 0.005 suggested the need of nonlinear (quadratic approximation that provided the better fit in age-related strength functions of females modelling postmenopausal disproportionalities.Keywords: osteoporosis, human lumbar vertebral body, regional compressive strength, load, stress, strain, young’s modulus, energy absorption capacity, age- and sex-dependence

Márta Kurutz

2008-12-01

284

Shear strength characteristics of Irbid clayey soil mixed with iron filling and iron filling-cement mixture  

Science.gov (United States)

Iron filling and iron filling-cement mixture were used to improve the shear strength characteristics of Irbid clayey soil. For this purpose, five types of Irbid clay soils were obtained and mixed with iron filling and iron filling-cement mixture at different percentages. Two sets of prepared samples were mixed with the admixture. The first set was prepared by mixing the soil samples with iron filling alone at 2.5, 5.0, 7.5, and 10% by dry weight of the soil. The second set was prepared by mixing with iron filling-cement mixture at equal ratio of the same percentages of the first set. An unconfined compression test was performed in this study to measure the shear strength properties of the soils. The test results showed that the increase in the percentages of the iron filling and iron filling-cement mixture up to 10% will result in increasing the maximum dry density of the soil and increase the unconfined compressive strength and the secant of modulus of elasticity of the clayey soil. Also, the addition of iron filling-cement mixture increased the unconfined compressive strength and secant modulus of elasticity of the clayey soil higher than the addition of iron filling alone.

Attom, Mousa F.

2008-08-01

285

Effect of Incorporating Nanoporous Metal Phosphate Materials on the Compressive Strength of Portland Cement  

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Full Text Available Nanoporous metal phosphate (NP-MPO materials are being developed for removal of contaminant oxyanions (As(OHO32−, CrO42−, and TcO4−, and cations (mercury, cadmium, and lead from water and waste streams. Following sequestration, incorporation of metal laden NP-MPOs as a portion of cement formulation would provide an efficient and low-cost way to immobilize metal laden NP-MPOs in an easily handled waste form suitable for permanent disposal. There are no known investigations regarding the incorporation of NP-MPOs in concrete and the effects imparted on the physical and mechanical properties of concrete. Results of this investigation demonstrated that incorporating of NP-MPO materials requires additional water in the concrete formulation which decreases the compressive strength. Thus, incorporation of NP-MPOs in concrete may not serve as an efficient means for long-term disposal.

Glen E. Fryxell

2008-03-01

286

A comparative in vitro study of microleakage by a radioactive isotope and compressive strength of three nanofilled composite resin restorations  

Science.gov (United States)

Aim: This study compares the compressive strength and microleakage of three nanofilled composites using radioactive isotope Ca45. Materials and Methods: Thirty-six freshly extracted human premolars were used in this study. Standardized Class I preparation was carried out and then randomly divided into three different groups: A, B, and C with 12 teeth in each group which were restored with nanofilled composite restoration and then subjected to thermocycling. Microleakage was tested using radioactive isotope Ca45. Kruskal–Wallis and Mann–Whitney tests were used to compare the microleakage scores of the three groups. For measuring the compressive strength of three nanofilled composite resin restorations, 12 specimens of each material were prepared in customized stainless steel cylindrical moulds of 6 mm ×4 mm. The compressive test was performed using the Universal Testing Machine. The values were analyzed with ANOVA and Bonferroni's test. Results: The findings of this study indicate that the synergy has the least microleakage and highest compressive strength followed by the Grandio and Filtek Z-350. Conclusions: Introduction of nanocomposites (packable) appears to have improved the performance of both anterior and posterior restorations with regard to mechanical properties, marginal integrity, and esthetics. PMID:21814351

Gogna, Rupika; Jagadis, S; Shashikal, K

2011-01-01

287

Evaluation of Shear Strength and Cone Penetration Resistance Behavior of Tropical Silt Loam Soil under Uni-Axial Compression  

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Full Text Available Laboratory investigations were conducted to study strength characteristics of silt loam soil of Ilorin, Kwara State, Nigeria, under uni-axial compression tests. The main objective of this study was to evaluate the effects of applied pressure and moisture content on strength indices such as bulk density, penetration resistance and shear strength of the soil and to develop relationships between the strength indices for predictive purposes necessary in soil management. The compression was carried out at different moisture contents determined according to the consistency limits of the soil. The applied pressure ranged from 75 to 600 kPa. Values of bulk density, penetration resistance and shear strength increased with increase in moisture content up to peak values after which the values decreased with further increase in moisture content. Regression models were used to describe the trends in the results for the soil. Results also showed that bulk density and soil strength normally regarded as indicators of soil quality are affected by moisture content and applied pressure and that these properties can be predicted using the models generated from the study.

Omolola C. Olaiya

2012-06-01

288

Effect of the Curing Conditions and Superplasticizer on Compressive Strength of Concrete Exposed To High Ambient Temperature of Nawabshah, Pakistan  

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Full Text Available The overall performance of the hardened concrete is believed to be greatly affected by the type and duration of the curing. The influence of the curing on the strength and durability of concrete becomes more significant when the concrete is to be exposed to high ambient temperature of the local area. This paper presents the results of an experimental study conducted to investigate effect of curing conditions and superplasticizer on compressive strength of concrete exposed to high ambient temperature. The cube specimens of standard size were cast and tested. The superplasticizer was used as percentage of cement being 0% to 2% with an increment of 5%. The specimens were cured initially in water for 3days, 7 days and 14 days and then exposed to the ambient environment up to the testing age. All the specimens were tested at 28 days. In addition, a batch of the specimens was cast and cured continuously in water for 28 days and another batch of the specimens was exposed to the high ambient temperature without initial wet curing. Both the batches were also tested at 28 days age. The results were compared to investigate the effect of initial wet curing and superplasticizer on compressive strength when it is exposed to the high ambient temperature. The results reveals that the compressive strength of concrete exposed to the high ambient temperature is significantly influenced by the wet curing period and the addition of superplasticizer.

Noor Ahmed Memon, Fahad ul Rehman Abro, Ubaidullah Memon, Salihuddin Radin Sumadi

2014-07-01

289

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

Science.gov (United States)

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.

Prahara, E.; Meilani

2014-03-01

290

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

Directory of Open Access Journals (Sweden)

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.

Prahara E.

2014-03-01

291

The effect of gamma irradiation on the strength and elasticity of climax stock and westerly granites  

International Nuclear Information System (INIS)

The authors performed compression tests on Climax Stock quartz monzonite (CSQM), half of which had received a gamma ray dose of 9 +- MGy (0.9 Grad) and half of which had not. They performed similar tests on Westerly granite. The experiment on CSQM was capable of detecting a 7% change in the unconfined strength level of 200 MPa. The experiment showed no statistically significant change. Null results were also found for the effect of gamma irradiation Young's modulus and Poisson's ratio in CSQM and for that on the compressional strength of Westerly granite. They thus conclude that gamma irradiation has no effect on the strengths of either CSMQ or Westerly grainite

292

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 co...

Babafemi A.J.; Olusola K.O.; Olawuyi B.J.

2012-01-01

293

Effect of sintering temperature on microstructure and compressive strength of B4C-AlSi eutectic alloy  

International Nuclear Information System (INIS)

The block neutron absorber of B4C based on Al-Si eutectic alloy has been prepared by powder-metallurgy method. The effects of sinter temperature on microstructure, compressive strength, and ductility of sintered billets have been investigated. It has been shown that the sintering temperature decides sensitively the compressive strength and ductility of sintered billets. Sintered under 550, 555, 560, and 565 degree C, the billet shows different states, such as sub-sintered, best-sintered, over-sintered, and molten. Sintered under 550 degree C, the powder have not been metallurgically combined with each other. Beyond 560 degree C, the billets are molten. The 555 degree C is the best sintering temperature, under which the powder have been partly melted and the metallurgical combination has been occurred, then the billets have a better ductility. (authors)

294

Compressive and splitting tensile strength of autoclaved aerated concrete (AAC) containing perlite aggregate and polypropylene fiber subjected to high temperatures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the results of an experimental study on the residual compressive and splitting tensile strength ofautoclaved aerated concrete (AAC) containing perlite and polypropylene (PP) fiber subjected to high temperatures. Cylinderspecimens were subjected to various temperature ranges of 100, 200, 400, 800, and 1,000°C. The mixtures were prepared withAAC cementitious materials containing perlite at 15%, 20%, and 30% sand replacement. The polypropylene fiber content of0, 0.5%, 1%, 1....

Borvorn Israngkura Na Ayudhya

2011-01-01

295

Compressive strength of masonry made of clay bricks and cementmortar: Estimation based on Neural Networks and Fuzzy Logic  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The use of mathematical tools such as Artificial Neural Networks and Fuzzy Logic has been shown to be useful for solving complex engineering problems, without the need to reproduce the phenomenon under study, when the only information available consists of the parameters of the problem and the desired results. Based on a collection of 96 laboratory tests, this paper uses Artificial Neural Networks and Fuzzy Logic to determine the compressive strength of a masonry structure composed of clay br...

Garzo?n Roca, Julio; Obrer Marco, Creu; Adam Marti?nez, Jose? Miguel

2013-01-01

296

Studies on the Determination of Compressive Strengths of Different Grades of Rice Husk Ash—An Ecofriendly Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rice Husk Ash (RHA) Concrete is an eco friendly concrete and has evolved as an innovative technology, capable of achieving the status of being an outstanding advancement in the sphere of concrete technology. The utilization of Rice Husk Ash (RHA) will reduce the dumping of rice husk as well as reduce the construction cost. In this communication investigations for the determination of residual compressive strength of M30

Patnaikuni Chandan Kumar; Venugopal, Nutulapati V. S.; Palli Malleswara Rao

2013-01-01

297

Association Analyses of RANKL/RANK/OPG Gene Polymorphisms with Femoral Neck Compression Strength Index Variation in Caucasians  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Femoral neck compression strength index (fCSI), a novel phenotypic parameter that integrates bone density, bone size, and body size, has significant potential to improve hip fracture risk assessment. The genetic factors underlying variations in fCSI, however, remain largely unknown. Given the important roles of the receptor activator of the nuclear factor-?B ligand/receptor activator of the nuclear factor-?B/osteoprotegerin (RANKL/RANK/OPG) pathway in the regulation of bone remodeling, we t...

Dong, Shan-shan; Liu, Xiao-gang; Chen, Yuan; Guo, Yan; Wang, Liang; Zhao, Jian; Xiong, Dong-hai; Xu, Xiang-hong; Recker, Robert R.; Deng, Hong-wen

2009-01-01

298

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Pelufo Carbonell, Mari?a Jose?; Domingo Cabo, Alberto; Ulloa Mayorga, Vivia?n Andrea; Vergara Acun?a, Needy Nayiv

2009-01-01

299

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 e...

Ahmadian Khoshemehr Leila; Arbabi Kalati Rasoul; Arbabi Kalati Parvin

2009-01-01

300

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

Science.gov (United States)

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.

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

2014-10-01

 
 
 
 
301

Experimental and statistical study of the influence of broken up particles and air content on the compressive strength of concretes  

International Nuclear Information System (INIS)

Companies in Algeria have restricted budgets devoted to the formulation of concrete. Therefore, very few research studies are interested by the concrete composition in accordance to its purpose. Hence, this work is a part of an approved research program assigned to clarify the impact of certain parameters on the quality of concrete. This experimental program consists of more than 700 cylindrical specimens of 16x32 cm that were made using local materials. Excluding the durability indicators towards the concrete, the compressive strength is the most significant property to be considered (Mounanga et al., 2006). The obtained results concern consistency and content air propertiesof the concrete at fresh state and compressive strength of hardened concrete at 28 days. Thus, the influence of the air content percentage on the concrete consistency is studied. Moreover, the influence of these two parameters on the compressive strength of the hardened concrete is also presented. The experimental results obtained constitute a data bank, which allows comparing through a statistical analysis, the model established by Feret (Baron and Ollivier, 1996) and the results of the tests. (author)

302

Use of nonlinear prediction tool to estimate uniaxial compressive strength and modulus of elasticity of some granitic rocks  

Science.gov (United States)

In several rock engineering applications, various prediction tools have been used to estimate strength and deformation parameters of intact rock. Commony, simple and linear multivariable regression methods have been employed. However, recently, some soft computing methods such as fuzzy inference systems, artificial neural Networks and neuro-fuzzy models have been used and they have yielded successful results, because the problems at hand have generally nonlinear nature. The purpose of the present study is to apply neuro-fuzzy modeling to estimate uniaxial compressive strength and modulus of elasticity of some granitic rocks from their physical and index properties. For the purpose of the study, sampling works on seven different granitic rocks from different locations in Turkey were performed. On these samples, unit weight, porosity, void ratio, water absorption by weight, P-wave velocity, point load index, block punch index, tensile strength, uniaxial compressive strength and modulus of elasticity were determined in laboratory. A total of 88 specimens were used during the laboratory tests. In the first stage of the analyses, stepwise multiple regression analyses were performed. By using the input parameters of the most successful regression models, some models based on adaptive neuro-fuzzy inference system (ANFIS) were developed to predict uniaxial compressive strength and modulus of elasticity. The general performances of the ANFIS models are considerably high. This results show that prediction of some intact rock properties is a nonlinear problem. For this reason, when predicting the intact rock properties, the nonlinear methods such as fuzzy inference system, artificial neural networks, adaptive neuro-fuzzy inference system or nonlinear multiple regression methods should be considered.

Gultekin, Nurgul; Sezer, Ebru; Gokceoglu, Candan

2010-05-01

303

Experimental studies on quantitative CT prediction of compressive strength of thoracolumbar vertebral bodies. Experimentelle Untersuchungen zur quantitativen computertomographischen Vorhersage der Kompressionsfestigkeit thorakolumbaler Wirbelkoerper  

Energy Technology Data Exchange (ETDEWEB)

Testing 98 motion segments we investigated the possibility of a prediction of the compressive strength of thoraco-lumbar vertebrae by QCT. The ultimate compressive strength can be predicted from the density of the trabecular bone and from the size of the endplates - both determined by QCT - with an error of 1 kN. The increase of compressive strength in cranio - caudal direction is calculated at approximately 0.3 kN per anatomical level. This variation is due to the increase of the endplate areas. (orig.).

Biggemann, M.; Hilweg, D.; Brinckmann, P. (Evangelisches Krankenhaus Bethesda gGmbH, Duisburg (Germany, F.R.). Radiologische Klinik und Strahleninstitut; Muenster Univ. (Germany, F.R.). Inst. fuer Experimentelle Biomechanik)

1989-09-01

304

Effect of early mobilisation on grip strength, pinch strength and work of hand muscles in cases of closed diaphyseal fracture radius-ulna treated with dynamic compression plating.  

Directory of Open Access Journals (Sweden)

Full Text Available AIMS: The purpose of the study was to objectively determine the effects of early mobilisation in terms of grip strength and work of hand muscles in cases of closed diaphyseal fracture radius - ulna treated with dynamic compression plating. SUBJECTS AND METHODS: Fifty normal subjects and Twenty-one patients, (Eleven patients treated with early active and resistive goal directed mobilisation and Ten control group were assessed for pinch strength and grip strength on Pinch Dynamometer and Jamar Dynamometer and work of hand muscles on Ergograph. Standardised positions of the equipments and patients were maintained throughout the study. RESULTS: Results showed highly significant reduction in performance in patients treated with early mobilisation as compared to normal subjects in their first assessment (Fourth week post operatively. These patients showed significant improvement in successive assessments (sixth & eighth post operative week on exercising in between these assessments. CONCLUSIONS: There are significant effects on grip strength and work of hand muscles in patients treated with that early active and resistive goal directed mobilisation.

Solanki P

2000-04-01

305

Static compressive strength prediction of open-hole structure based on non-linear shear behavior and micro-mechanics  

Science.gov (United States)

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.

Li, Wangnan; Cai, Hongneng; Li, Chao

2014-11-01

306

Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression.

Pinkerton, G.W.

1993-12-31

307

Compression Strength Testing for Automotive Brake Pads Used in Earthquake Energy Dampers  

Directory of Open Access Journals (Sweden)

Full Text Available In order to calibrate a friction damper which uses automotive brake pads it is necessary to determine the compression behaviour of the friction material. This paper summarizes the experimental results obtained for a set of automotive brake pads made in Romania. These results are useful in order to determine the slip load level in a seismic energy dissipation mechanism which uses this type of friction pads. The paper presents the experimental set up and the compression behaviour curves obtained for a set of four commercial brake pads. The testing was performed by the author as a part of his research work, using a hydraulic compression press.

Drago? Voiculescu

2010-01-01

308

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)

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.

S. S, Pathak

2012-10-01

309

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)

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 (?) and modulus (E).

Dowling, Adam H

2011-06-01

310

Further investigation on the dynamic compressive strength enhancement of concrete-like materials based on split Hopkinson pressure bar tests Part II Numerical Simulations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Split Hopkinson pressure bars (SHPB) have been used widely to measure the dynamic compressive strength of concrete-like materials at high strain-rate between 101 and 103 s?1. It has been shown in companion paper (Zhang et al. 2009) that the axial strain acceleration is normally unavoidable in an SHPB test on brittle materials. Axial strain acceleration introduces radial confinement in the SHPB specimens and consequently enhances the compressive strength of concrete-like ...

Li, Q. M.; Lu, Y. B.; Meng, H.

2009-01-01

311

Compression Strength Testing for Automotive Brake Pads Used in Earthquake Energy Dampers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In order to calibrate a friction damper which uses automotive brake pads it is necessary to determine the compression behaviour of the friction material. This paper summarizes the experimental results obtained for a set of automotive brake pads made in Romania. These results are useful in order to determine the slip load level in a seismic energy dissipation mechanism which uses this type of friction pads. The paper presents the experimental set up and the compression behaviour curves obtaine...

Drago? Voiculescu

2010-01-01

312

Damage-cluster distributions and size effect on strength in compressive failure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate compressive failure of heterogeneous materials on the basis of a continuous progressive damage model. The model explicitely accounts for tensile and shear local damage and reproduces the main features of compressive failure of brittle materials like rocks or ice. We show that the size distribution of damage-clusters, as well as the evolution of an order parameter, the size of the largest damage-cluster, argue for a critical interpretation of fracture. The comp...

Girard, Lucas; Weiss, Je?ro?me; Amitrano, David

2012-01-01

313

Case history rock mechanics examination of the Jefferson Island Salt Mine: III. Evaluation of laboratory specimen dimensions on the uniaxial strength and deformational characteristics of dome salt  

International Nuclear Information System (INIS)

This report presents the results of a laboratory effort to determine the unconfined strength and elastic properties of dome salt from the Diamond Crystal Mine, Jefferson Island, LA. The effects of sample size and geometry on the compressive properties of this salt were investigated, and relationships for compressive strength and deformational modulus as a function of specimen diameter and length to diameter ratio were developed. The results of a finite-element analysis of the stress state in a specimen loaded between steel platens are also presented. 20 figures, 4 tables

314

A study on the compressive and tensile strength of foamed concrete containing pulverized bone as a partial replacement of cement  

International Nuclear Information System (INIS)

In this study, structural properties of foamed aerated concrete with and without pulverized bone were investigated. These properties are workability, plastic and testing densities, compressive strength, and tensile strength at the design density of 1600kg/m/sub 3/. The tensile strength was evaluated by subjecting 150 x 150 x750mm unreinforced foamed concrete beams to flexural test and 150x300mm cylinder specimens were subjected to splitting test. 150mm cube specimens were used for the determination of both the compressive strength and the testing density of the foamed aerated concrete. The plastic density was investigated using a container of known volume, and its workability determined using the slump test. The pulverized bone content was varied from 0 to 20% at interval of 5%. The specimens without the pulverized bone served as the control. At the designed density of 1600 kg/m/sub 3/, the results for the control specimens at 28-day curing age are 15.43 and 13.89N/mm/sub 2/ for air-and water-cured specimens respectively. The modulus of rupture and splitting tensile strength are 2.53 and 1.63N/mm/sub 2/ respectively. The results for specimens with pulverized bone did not differ significantly from the specimens without pulverized bone. From the results of this investigation, it can be concluded that foamed aerated concrete used for this study has potential for structural applications. Also pulverized bone can be used to reduce (partially replace) the quantity of cement used in aerated concrete production; thus ridding our environment of potentially harmful wastes, as well as reduce the consumption of non-renewable resources. (author)

315

Multicriteria decision-making analysis based methodology for predicting carbonate rocks' uniaxial compressive strength  

Directory of Open Access Journals (Sweden)

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 los materiales rocosos. Sin embargo, una prueba de RCU es costosa, lleva mucho tiempo para hacerlo en el laboratorio y requiere muestras de núcleos de alta calidad que tienen una geometría regular.

Por lo tanto, ecuaciones empíricas fueron propuestas para la predicción de RCU como una función de las propiedades índice de las rocas. Las metodologías de proceso analítico jerárquico (PAJ y análisis de regresión múltiple fueron utilizados (en vez de los métodos tradicionales de regresión lineal en conjuntos de datos obtenidos de las rocas carbonatadas en el noreste de Turquía Muestras de rocas calizas que van desde el Devónico hasta finales del Cretácico fueron escogidas; muestras de travertino y ónix fueron seleccionadas de ambientes morfológicos teniendo en cuenta sus condiciones ambientales de superficie.

Los resultados de los experimentos llevados a cabo en alrededor de 250 muestras de rocas carbonatadas fueron utilizados para derivar un modelo Mientras que el modelo de jerarquía se centró en determinar las propiedades índice más importantes afectados por la RCU, el análisis de regresión establece relaciones significativas entre la RCU y las propiedades del índice; coeficientes de correlación positivas de 0,85 y 0,83 fueron determinadas por análisis de regresión entre las variables La metodología proporciona una alternativa adecuada para la estimación cuantitativa de la RCU y evita la necesidad de realizar pruebas del laboratorio las cuales son tediosas y dispendiosas

Ersoy Hakan

2012-10-01

316

Multicriteria decision-making analysis based methodology for predicting carbonate rocks' uniaxial compressive strength  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish 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 los materiales rocosos. Sin embargo, una prueba de RCU es costosa, lle [...] va mucho tiempo para hacerlo en el laboratorio y requiere muestras de núcleos de alta calidad que tienen una geometría regular. Por lo tanto, ecuaciones empíricas fueron propuestas para la predicción de RCU como una función de las propiedades índice de las rocas. Las metodologías de proceso analítico jerárquico (PAJ) y análisis de regresión múltiple fueron utilizados (en vez de los métodos tradicionales de regresión lineal) en conjuntos de datos obtenidos de las rocas carbonatadas en el noreste de Turquía Muestras de rocas calizas que van desde el Devónico hasta finales del Cretácico fueron escogidas; muestras de travertino y ónix fueron seleccionadas de ambientes morfológicos teniendo en cuenta sus condiciones ambientales de superficie. Los resultados de los experimentos llevados a cabo en alrededor de 250 muestras de rocas carbonatadas fueron utilizados para derivar un modelo Mientras que el modelo de jerarquía se centró en determinar las propiedades índice más importantes afectados por la RCU, el análisis de regresión establece relaciones significativas entre la RCU y las propiedades del índice; coeficientes de correlación positivas de 0,85 y 0,83 fueron determinadas por análisis de regresión entre las variables La metodología proporciona una alternativa adecuada para la estimación cuantitativa de la RCU y evita la necesidad de realizar pruebas del laboratorio las cuales son tediosas y dispendiosas Abstract in english 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 req [...] uires 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

Ersoy, Hakan; Derya, Kanik.

2012-06-01

317

Evaluation of Soil Compaction Strength (Pre-Compaction Stress Using Plate Sinkage and Uniaxial Confined Compression Tests  

Directory of Open Access Journals (Sweden)

Full Text Available For prevention of soil compaction, knowledge of allowable compression stress limit (compaction strength in soil is important. Pre-compaction stress ( ?pc was introduced as soil compaction strength and often used as a criterion for evaluation of soil susceptibility to compaction. In this research, pre-compaction stress was measured for a sandy loam soil with plate sinkage (PST and confined compression (CCT tests. To prepare soil samples with different initial compactness, two soil water contents (17 and 19%db and six pre-loading stresses (0, 25, 50, 100, 150 and 200 kPa were used. The effects of soil water content and pre-loading stress on estimated pre-compaction stress were studied using a factorial experiment in a completely randomized design with three replications. The ?pcvalues were significantly influenced by loading combination and soil water content. For PST, pre-load increase and higher soil water content resulted in higher and lower values of ?pc , respectively. However, predicted ?pc value increased with higher soil water content for CCT. The results also showed that the ?pc predicted with PST was accurate, whereas the values obtained with CCT were 4.5 (at 17 %db and 8.5 (at 19 %db times higher than the applied pre-loads. Overall, the findings indicated that ?pc prediction depends on the compression test, and PST could be a suitable method for soil pre-compaction stress (compaction strength determination in sustainable soil management, i.e., soil trafficability and tillage. The PST method is also suitable to assess the effect of managing factors on pre-compaction stress.

M. R. Masaddeghi

2008-07-01

318

Influence Factor Analysis on Strength of Lime-Fly Ash Loess  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Lime-fly ash loess is composed of fly ash, lime and loess. It is a new material in subgrade backfill. Main factors to influence the strength of lime-fly ash loess are age, amount of fly ash and lime, ratio of fly ash to lime (1:K), and moisture content. In order to observe the effect of each factor influencing the strength of lime-fly ash loess and find out the relationship between each other, this paper adopted orthogonal test design to conduct unconfined compression tests. The result shows ...

Yufen Zhang; Zhiquan Zhang

2013-01-01

319

Effect of Wet and Dry Conditions on Strength of Silty Sand Soils Stabilized with Epoxy Resin Polymer  

Directory of Open Access Journals (Sweden)

Full Text Available This study reports on a laboratory experiment conducted to evaluate the stabilization of a silty-sand (SM material with epoxy resin and effect of wet and dry conditions on strength of stabilized silty sand. The additive mixture was composed of a 1:0.15 of epoxy resin to polyamide hardener. Specimens were prepared by adding different amount of epoxy resin polymer emulsion (3, 4 and 5% to silty sand with (0, 10, 20, 30, 35, 45 and 60% silt content at dry density of 17 kN m-3. The unconfined compressive strength of specimens determined with uniaxial test and compared to each other under the same mixing, compaction and curing condition to derivation the effect of polymer emulsion on silty sand. All specimens submerged in water for 24, 96 and 168 h and then taken out from the water and their unconfined compressive strength were recorded. The results of this study indicated that the addition of epoxy resin improves significantly the compressive strength and modulus of elasticity of samples under dry condition. This improvement depends on the content of polymer and silt. However, polymer significantly enhanced the strength of the samples after 7 days of submerging in water but strength of wet samples is less than the dry samples.

Masoud Ghorbanalizadeh

2010-01-01

320

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

FAREED AHMED MEMON; MUHD FADHIL NURUDDIN; SADAQATULLAH KHAN; NASIR SHAFIQ; TEHMINA AYUB

2013-01-01

 
 
 
 
321

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Prahara E.; Meilani

2014-01-01

322

Use of Nano-SiO2 to Improve Microstructure and Compressive Strength of Recycled Aggregate Concretes  

Science.gov (United States)

The purpose of this paper is to provide new type of recycled aggregate concrete (RAC) incorporating nano-SiO2. In particular, we investigate the effects of colloidal nano-silica solution on the properties of fresh and hardened concrete. The main variables included the dosage of nano-silica (including 0%, 1.5%, and 3% of cement content) and the cement content of the concrete (including 400 and 450 kg/m3). Results were compared with plain concretes. Tests were conducted to determine the mechanical properties (compressive strength) and microstructure (SEM test) of the concretes.

Hosseini, P.; Booshehrian, A.; Delkash, M.; Ghavami, S.; Zanjani, M. K.

323

Measurement of In-Plane Shear Strength of Carbon/Carbon Composites by Compression of Double-Notched Specimens  

Science.gov (United States)

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.

Yan, K. F.; Zhang, C. Y.; Qiao, S. R.; Song, C. Z.; Han, D.; Li, M.

2012-01-01

324

The effect of welding on the strength of aluminium stiffened plates subject to combined uniaxial compression and lateral pressure  

Directory of Open Access Journals (Sweden)

Full Text Available Nowadays aluminum stiffened plates are one of the major constituents of the marine structures, espe¬cially high-speed vessels. On one hand, these structures are subject to various forms of loading in the harsh sea envi¬ronment, like hydrostatic lateral pressures and in-plane compression. On the other hand, fusion welding is often used to assemble those panels. The common marine aluminum alloys in the both 5,000 and 6,000 series, however, lose a re¬markable portion of their load carrying capacity due to welding. This paper presents the results of sophisticated finite-element investigations considering both geometrical and mechanical imperfections. The tested models were those pro¬posed by the ultimate strength committee of 15th ISSC. The presented data illuminates the effects of welding on the strength of aluminum plates under above-mentioned load conditions.

Pedram Masoud

2014-03-01

325

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

Directory of Open Access Journals (Sweden)

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.

Pudjisuryadi, P.

2013-01-01

326

Toroidal, compression, and vortical dipole strengths in 144-154Sm: Skyrme-RPA exploration of the deformation effect  

International Nuclear Information System (INIS)

A comparative analysis of toroidal, compressional and vortical dipole strengths in the spherical 144Sm and the deformed 154Sm is performed within the random-phase approximation using a set of different Skyrme forces. Isoscalar (T = 0), isovector (T = 1), and electromagnetic excitation channels are considered. The role of the nuclear convection jcon and magnetization jmag currents is inspected. It is shown that the deformation leads to an appreciable redistribution of the strengths and causes a spectacular deformation splitting (exceeding 5 MeV) of the isoscalar compressional mode. When stepping from 144Sm to 154Sm, we observe an increase of the toroidal, compression and vortical contributions in the low-energy region (often called pygmy resonance). The strength in this region seems to be an overlap of various excitation modes. The energy centroids of the strengths depend significantly on the isoscalar effective mass m0. Skyrme forces with a large m0 (typically m0/m ? 0.8 - 1) seem to be more suitable for the description of experimental data for the isoscalar giant dipole resonance. (orig.)

327

Toroidal, compression, and vortical dipole strengths in {sup 144-154}Sm: Skyrme-RPA exploration of the deformation effect  

Energy Technology Data Exchange (ETDEWEB)

A comparative analysis of toroidal, compressional and vortical dipole strengths in the spherical {sup 144}Sm and the deformed {sup 154}Sm is performed within the random-phase approximation using a set of different Skyrme forces. Isoscalar (T = 0), isovector (T = 1), and electromagnetic excitation channels are considered. The role of the nuclear convection j{sub con} and magnetization j{sub mag} currents is inspected. It is shown that the deformation leads to an appreciable redistribution of the strengths and causes a spectacular deformation splitting (exceeding 5 MeV) of the isoscalar compressional mode. When stepping from {sup 144}Sm to {sup 154}Sm, we observe an increase of the toroidal, compression and vortical contributions in the low-energy region (often called pygmy resonance). The strength in this region seems to be an overlap of various excitation modes. The energy centroids of the strengths depend significantly on the isoscalar effective mass m{sub 0}. Skyrme forces with a large m{sub 0} (typically m{sub 0}/m {approx} 0.8 - 1) seem to be more suitable for the description of experimental data for the isoscalar giant dipole resonance. (orig.)

Kvasil, J.; Bozik, D. [Charles University, Institute of Particle and Nuclear Physics, Praha 8 (Czech Republic); Nesterenko, V.O. [Joint Institute for Nuclear Research, Laboratory of Theoretical Physics, Moscow region (Russian Federation); Kleinig, W. [Joint Institute for Nuclear Research, Laboratory of Theoretical Physics, Moscow region (Russian Federation); Inst. fuer Analysis, Technische Universitaet Dresden, Dresden (Germany); Reinhard, P.G. [Universitaet Erlangen, Institut fuer Theoretische Physik II, Erlangen (Germany); Lo Iudice, N. [Universita di Napoli Federico II, Dipartimento di Scienze Fisiche, Napoli (Italy); Istituto Nazionale di Fisica Nucleare, Napoli (Italy)

2013-09-15

328

The Strength of Single Crystal Copper under Uniaxial Shock Compression at Mbar pressures  

Energy Technology Data Exchange (ETDEWEB)

In situ x-ray diffraction has been used to measure the shear strain (and thus strength) of single crystal copper shocked to Mbar pressures along the [001] and [111] axes. These direct shear strain measurements indicate shear strengths at these ultra-high strain rates (of order 10{sup 9} s{sup -1}) of a few GPa, which are both broadly in agreement with the extrapolation of lower strain-rate data and with non-equilibrium molecular dynamics simulations.

Murphy, W; Higginbotham, A; Kimminau, G; Barbrel, B; Bringa, E; Hawreliak, J; Koenig, M; McBarron, W; Meyers, M; Nagler, B; Ozaki, N; Park, N; Remington, B; Rothman, S; Vinko, S M; Whitcher, T; Wark, J

2009-05-21

329

An extrapolation method for compressive strength prediction of hydraulic cement products  

Energy Technology Data Exchange (ETDEWEB)

The basis for the AMEBA Method is presented. A strength-time function is used to extrapolate the predicted cementitious material strength for a late (ALTA) age, based on two earlier age strengths--medium (MEDIA) and low (BAIXA) ages. The experimental basis for the method is data from the IPT-Brazil laboratory and the field, including a long-term study on concrete, research on limestone, slag, and fly-ash additions, and quality control data from a cement factory, a shotcrete tunnel lining, and a grout for structural repair. The method applicability was also verified for high-performance concrete with silica fume. The formula for predicting late age (e.g., 28 days) strength, for a given set of involved ages (e.g., 28,7, and 2 days) is normally a function only of the two earlier ages` (e.g., 7 and 2 days) strengths. This equation has been shown to be independent on materials variations, including cement brand, and is easy to use also graphically. Using the AMEBA method, and only needing to know the type of cement used, it has been possible to predict strengths satisfactorily, even without the preliminary tests which are required in other methods.

Siqueira Tango, C.E. de [IPT-Technological Research Inst., Sao Paulo (Brazil)

1998-07-01

330

Compressive strength and ductility of short concrete columns reinforced by bamboo  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents the structural and environmentally sustainable aspects of bamboo as a reinforcing material insteadof steel reinforcement in concrete columns. Seven small-scale short columns (125 mm x 125 mm x 600 mm with different typeof reinforcements were tested under concentric loading to investigate strength capacity and ductility. The results showedthat the strength capacity of short columns reinforced by bamboo without surface treatment could resist the axial load asstructurally required by ACI318-05, but ductility was rather low especially the column that was reinforced by 1.6 percent ofreinforcing bamboo which showed brittle behavior similar to that of plain concrete column. This was thought to be an effectof water absorption and a loss of bonding strength between concrete and bamboo. On the other hand, columns reinforcedby bamboo treated with water-repellent substance, Sikadur-31CFN, showed higher strength and ductility than columnsreinforced by untreated bamboo. The result also showed that 1.6 % of steel reinforcement, in relation to the column crosssection,could be replaced by 3.2% of treated reinforcing bamboo, for similar behavior, strength and ductility.

Satjapan Leelatanon

2010-08-01

331

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 str...

Juliette Fitremann; Ariane Bercier; Olivier Lignon; Stéphane Gonçalves

2010-01-01

332

The Effects of Friction on the Compressive Behaviour of High Strength Steels  

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An investigation, covering a wide range of strain rate and temperature has been performed into the effects of interfacial friction on the compressive properties of an armour plate steel. In order to calculate the coefficient of friction, ring tests were carried out and the Avitzur analysis applied. In general coefficients of friction decreased with increasing temperature and strain rate. Other specimen observations indicated the same friction trends. It is essential that friction corrections ...

Ashton, M.; Parry, D.

1997-01-01

333

The fracture strength of TRISO-coated particles determined by compression testing between soft aluminium anvils  

International Nuclear Information System (INIS)

Compression testing of tri-isotropic (TRISO) carbon/silicon carbide-coated fuel particles between anvil materials with a wide range of hardnesses was investigated. During compression testing, the particle produces a hardness impression before it fractures. For subsequent measurements, the same position can therefore not be used. A special testing machine was designed to use the same set of anvils for testing more than one specimen. By each time positioning a particle at a slightly different position between the anvils, a large number of measurements could be made. The load required for fracture is almost independent of anvil hardness for very hard or very soft anvils. Finite element stress analysis showed that when the anvil hardness is very high, fracture occurs because of high local contact bending stresses at the point of contact. In the case of very soft anvils, a tensile stress develops along a latitudinal direction along the perimeter of the particle over a large volume in between the contact zones with the anvils. The particle then fractures by the development of cracks at right angles to the direction of the tensile stress. From the fracture load, the ability of the particle to withstand internal pressure can be assessed. The advantages of using compression testing of full particles between soft anvils without prior preparation to complement previous test methods are highlighted.

334

Compressive and Flexural Strengths for Considerable Volume Fly-Ash Concrete  

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The use of considerable volume of fly ash concrete in replacement of cement is economically and environmentally benefic because the fly ash is cheaper and produces fewer emissions of greenhouse gases than the conventional Portland cement. By using 30; 40 and 50 percent of fly ash in cementitious materials, after comparing different results of samples tested, the 28 days high-performance fly ash concrete resisted to the compressive loading forces respectively equal to 30.9MPa; 29.7MPa and 26.2...

Ndihokubwayo, Athanase

2011-01-01

335

Prediction of 28-day compressive strength of concrete on the third day using artificial neural networks  

Directory of Open Access Journals (Sweden)

Full Text Available In recent decades, artificial neural networks are known as intelligent methods formodeling of behavior of physical phenomena. In this paper, implementation of anartificial neural network has been developed for prediction of compressivestrength of concrete. A MISO (Multi Input Single Output adaptive system hasbeen introduced which can model the proposed phenomenon. The data hasbeen collected by experimenting on concrete samples and then the neuralnetwork has been trained using these data. From among 432 specimens, 300data sample has been used for train, 66 data sample for validation and 66 datasample for the final test of the network. The 3-day strength parameter of concretein the introduced structure also has been used as an important index forpredicting the 28-day strength of the concrete. The simulations in this paper arebased on real data obtained from concrete samples which indicate the validity ofthe proposed tool.

Vahid. K. Alilou

2010-01-01

336

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 confin...

Pudjisuryadi, P.; Tavio .

2013-01-01

337

Factors affecting early compressive strength of alkali activated fly ash (OPC-free) concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the findings of experimental research into the chief characteristics of a new type of concrete made solely with alkali activated fly ash (AAFA): i.e., free of ordinary Portland cement (OPC). The results of testing to determine specific properties of the fresh concrete and the development of its mechanical strength showed that most of the factors that affect the manufacture and final properties of Portland cement concrete (water/cement ratio, curing conditions, etc...

Ferna?ndez-jime?nez, Ana; Palomo, A.

2007-01-01

338

A comparative study of the compressive, flexural and bond strength of brick masonry.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Due to their physical and chemical properties, mortars made with lime are considered to be more compatible with historic fabrics than those made with artificial cements. This paper intends to contribute to the knowledge of the behavior of lime mortar masonry, by exploring the mechanical properties of clay brick masonry bound with both hydraulic and non-hydraulic lime mortars. Masonry wallettes built with a (non-hydraulic) low-strength, calcium lime binder (CL90-s) and a natural-hydraulic-lime...

Pavia, Sara

2009-01-01

339

Factors affecting early compressive strength of alkali activated fly ash (OPC-free) concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the findings of experimental research into the chief characteristics of a new type of concrete made solely with alkali activated fly ash (AAFA): i.e., free of ordinary Portland cement (OPC). The results of testing to determine specific properties of the fresh concrete and the development of its mechanical strength showed that most of the factors that affect the manufacture and final properties of Portland cement concrete (water/cement ratio, curing conditions, etc.) also i...

Palomo, A.; Fern Ndez-jim Nez, A.

2007-01-01

340

A novel dentin bond strength measurement technique using the composite disk in diametral compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We evaluated the feasibility of using the modified Brazilian disk test to measure the post-dentin interfacial bond strength. Advanced nondestructive examination and imaging techniques in the form of acoustic emission (AE) and digital image correlation (DIC) were used innovatively to capture the fracture process in real time. DIC showed strain concentration first appearing at one of the lateral sides of the post-dentin interface. The appearance of the interfacial strain concentration also coin...

Huang, Shih-hao; Lin, Lian-shan; Rudney, Joel; Jones, Rob; Aparicio, Conrado; Lin, Chun-pin; Fok, Alex S. L.

2012-01-01

 
 
 
 
341

A unified approach for extracting strength information from nonsimple compression waves. Part I: Thermodynamics and numerical implementation  

Science.gov (United States)

We describe a comprehensive method of extracting estimates of the complete plastic deformation behavior, including full deviatoric-stress/plastic-strain (? - ?) curves, from one-dimensional dynamic compression experiments at moderate pressures (up to ˜50 GPa). The method combines and extends selected aspects of previous approaches and features a second-order velocity interpolation function designed to accommodate highly rate-dependent phenomena. Assumptions, and the expected limitations thereof, are made explicit and kept to a minimum. In particular, we do not assume any particular plasticity model, nor do we assume that the wave propagation is either simple or steady. Instead, we allow the data themselves to constrain any such behavior. We develop generalizations of standard equation-of-state analyses that account for the effects of rate-dependent relaxation on wave speeds and paths through thermodynamic space and show the potential to extract a great deal of strength information from the details of wave propagation.

Reed, Bryan W.; Stolken, James S.; Minich, Roger W.; Kumar, Mukul

2011-12-01

342

Unconfined versus confined speleogenetic settings: variations of solution porosity.  

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Speleogenesis in confined settings generates cave morphologies that differ much from those formed in unconfined settings. Caves developed in unconfined settings are characterised by broadly dendritic patterns of channels due to highly competing development. In contrast, caves originated under confined conditions tend to form two- or three-dimensional mazes with densely packed conduits. This paper illustrates variations of solution (channel) porosity resulted from speleogenesis in unconfined ...

Klimchouk, A. B.

2006-01-01

343

Use of steel fibres recovered from waste tyres as reinforcement in concrete: pull-out behaviour, compressive and flexural strength.  

Science.gov (United States)

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 geometric properties. Finally, flexural tests furnished in some cases results comparable to those obtained when using ISF as concerns the post-cracking behaviour. PMID:19167204

Aiello, M A; Leuzzi, F; Centonze, G; Maffezzoli, A

2009-06-01

344

STUDIES ON EFFECT OF PERCENTAGE OF CARBON ON THE TENSILE & COMPRESSIVE STRENGTH OF STRUCTURAL STEEL  

Directory of Open Access Journals (Sweden)

Full Text Available The basic necessity of performing these process is that to improve the tensile strength, hardness, dimensional stability & wear resistance by passing the material through cooled area which enhance the hardness of the material because there is an increment takes place in the percentage of martensite in the structure. If such type of process are used in manufacturing the steel of different category which enhances the properties of material at the stage of cooling in negative temperature with the use of liquid nitrogen or other cooling media & all these products are used in different areas with greater performance. Result shows that the tensile strength of material is increased as we cool the material in negative temperature within the same elongation after its manufacture i.e. 741.27 N/mm² to maximum of 793 N/mm² at -15OC & 802 N/mm² at -30OC & 168.25 BHN to a maximum of 199 BHN at -15OC & 260 BHN at -30OC after cold treatment.

JAI PRAKASH SHARMA

2012-05-01

345

Effect of the Forming Conditions on the Compressive Strength of Fuel Elements for HTGR  

International Nuclear Information System (INIS)

Generation-IV reactors have been developed for the safety, high burn-up, long-term irradiation cycle and the hydrogen production. High Temperature Gas cooled Reactor (HTGR), one of the Gen-IV reactors, uses the fuel element which is manufactured by mixing and combining TRISO particles with graphite powder. The graphite powder is pressed with TRISO particles, previously formed with chemical bonding by pyrolizing with FB-CVD (Fluidized Bed-Chemical Vapor Deposition). H-451 Graphite for HTGR was qualified by NRC in the past, but is no longer available. Therefore, the research for new graphite will be necessary. There are many candidates from the graphite powder suppliers such as SGL cop., Graftech and Toyo Tanso suggested by NRC. The most important point of the graphite matrix is the strength for the high reliability, because the graphite matrix should be enable to protect the TRISO particles from the irradiation environment and the impact from the outside. In this research, several kinds of graphite and PVB as binder were chosen and mixed with each other for strength test. The objective of this research is to evaluate and optimize the kind and composition of the graphites and the forming process

346

Effect of the Forming Conditions on the Compressive Strength of Fuel Elements for HTGR  

Energy Technology Data Exchange (ETDEWEB)

Generation-IV reactors have been developed for the safety, high burn-up, long-term irradiation cycle and the hydrogen production. High Temperature Gas cooled Reactor (HTGR), one of the Gen-IV reactors, uses the fuel element which is manufactured by mixing and combining TRISO particles with graphite powder. The graphite powder is pressed with TRISO particles, previously formed with chemical bonding by pyrolizing with FB-CVD (Fluidized Bed-Chemical Vapor Deposition). H-451 Graphite for HTGR was qualified by NRC in the past, but is no longer available. Therefore, the research for new graphite will be necessary. There are many candidates from the graphite powder suppliers such as SGL cop., Graftech and Toyo Tanso suggested by NRC. The most important point of the graphite matrix is the strength for the high reliability, because the graphite matrix should be enable to protect the TRISO particles from the irradiation environment and the impact from the outside. In this research, several kinds of graphite and PVB as binder were chosen and mixed with each other for strength test. The objective of this research is to evaluate and optimize the kind and composition of the graphites and the forming process

Lee, Chung Yong; Lee, Seung Jae; Suh, Jung Min; Jo, Young Ho [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of); Lee, Young Woo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

347

Properties of confined and unconfined water  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this work is to add to the long lasting efforts to provide an unified picture of the properties of confined and unconfined water. Water is an ubiquitous substance with special importance for geological and biological as well as technical processes. There are 1.4 billion km3 of water on earth, most of it in liquid form, 0.001% as vapor in the atmosphere and 1.8% as ice (mainly crystalline hexagonal ice Ih) frozen at the poles and in Greenland [1]. But wa...

Guse, Christa

2011-01-01

348

The effect of fly ash and limestone fillers on the viscosity and compressive strength of self-compacting repair mortars  

Energy Technology Data Exchange (ETDEWEB)

Today, self-compacting mortars are preferred for repair purposes due to the application easiness and mechanical advantages. However, for self-compatibility, the paste phase must meet some certain criteria at fresh state. The cement as well as the ingredients of the paste, powders with cementitious, pozzolanic or inert nature and plasticizing chemical admixtures should be carefully chosen in order to obtain a suitable paste composition to enrich the granular skeleton of the mix. The physical properties of powders (shape, surface morphology, fineness, particle size distribution, particle packing) and physico-chemical (time-dependent hydration reactions, zeta potentials) interactions between cement powder and plasticizer should be taken into consideration. All these parameters affect the performance of fresh paste in different manners. There is no universally accepted agreement on the effect of these factors due to the complexity of combined action; thus, it is hard to make a generalization. This study deals with the selection of amount and type of powders from the viewpoint of fresh state rheology and mechanical performance. The influence of powder materials on self-compatibility, viscosity and strength were compared with a properly designed set of test methods (the mini-slump, V-funnel tests, viscosity measurements and compressive strength tests). It may be advised that, for each cement-powder-plasticizer mixture, a series of test methods can be used to determine the optimum content and type of materials for a specified workability.

Burak Felekoglu; Kamile Tosun; Bulent Baradan; Akin Altun; Bahadir Uyulgan [Dokuz Eylul University (Turkey). Faculty of Engineering

2006-09-15

349

The effects of geometrical imperfections on the ultimate strength of aluminium stiffened plates subject to combined uniaxial compression and lateral pressure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present study aims at determining the effects of the geometrical imperfections on the ultimate strength and load-carrying capacity of aluminium stiffened plates under combined axial compression and lateral pressure. The finite element models proposed by the Committee III.1 ‘Ultimate Strength’ of ISSC’2003 are used in the present investigation. Initial imperfections as proposed by ISSC committee as well as those recommended by Ship Structure Committee are considered in the a...

Khedmati, Mohammad Reza; Pedram, Masoud; Rigo, Philippe

2012-01-01

350

Phase transition and strength of vanadium under shock compression up to 88 GPa  

Science.gov (United States)

A series of reverse-impact experiments were performed on vanadium at shock pressure ranging from 32 GPa to 88 GPa. Particle velocity profiles measured at sample/LiF window interface were used to estimate the sound velocities, shear modulus, and yield stress in shocked vanadium. A phase transition at ˜60.5 GPa that may be the body-centered cubic (BCC) to rhombohedral structure was identified by the discontinuity of the sound velocity against shock pressure. This transition pressure is consistent with the results from diamond anvil cell (DAC) experiments and first-principle calculations. However, present results show that the rhombohedral phase has higher strength and shear modulus than the BCC phase, which is contrast to the findings from DAC experiments and theoretical work.

Yu, Yuying; Tan, Ye; Dai, Chengda; Li, Xuemei; Li, Yinghua; Wu, Qiang; Tan, Hua

2014-11-01

351

Hierarchical order of influence of mix variables affecting compressive strength of sustainable concrete containing fly ash, copper slag, silica fume, and fibres.  

Science.gov (United States)

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. PMID:24707213

Natarajan, Sakthieswaran; Karuppiah, Ganesan

2014-01-01

352

Comparative analysis of compressive strength tests at age of 28 and 90 days and density of products using chemical additives in cementing radioactive waste  

Energy Technology Data Exchange (ETDEWEB)

In this research it has been studied the effects of chemical additives (admixtures) in the cementation process of radioactive wastes, which are used to improve the properties of waste cementation process, both of the paste and of the solidified product. However there are a large variety of these materials that are frequently changed or taken out of the market, then it is essential to know the commercially available materials and their effects. The tests were carried out with a solution simulating the evaporator concentrate waste coming from PWR nuclear reactors. It was cemented using two formulations, A and B, incorporating higher or lower amount of waste, respectively. It was added chemical admixtures from two manufacturers (S and H), which were: accelerators, set retarders and superplasticizers. The experiments were organized by a factorial design 2{sup 3}. The measured parameters were the viscosity, the setting time, the paste and product density and the compressive strength. In this study we performed comparative analyzes of the results of compressive strength at age of 28 and 90 days and between the densities of the samples at the same ages.The compressive strength test at age of 28 days is considered a parameter essential issues related to security handling, transport and storage of cemented waste product. The results showed that the addition of accelerators improved the compressive strength of the cemented product, but presented lower values density products. (author)

Vieira, Vanessa Mota; Tello, Cledola Cassia Oliveira de, E-mail: vanessamotavieira@gmail.com, E-mail: tellocc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2013-07-01

353

Comparative analysis of compressive strength tests at age of 28 and 90 days and density of products using chemical additives in cementing radioactive waste  

International Nuclear Information System (INIS)

In this research it has been studied the effects of chemical additives (admixtures) in the cementation process of radioactive wastes, which are used to improve the properties of waste cementation process, both of the paste and of the solidified product. However there are a large variety of these materials that are frequently changed or taken out of the market, then it is essential to know the commercially available materials and their effects. The tests were carried out with a solution simulating the evaporator concentrate waste coming from PWR nuclear reactors. It was cemented using two formulations, A and B, incorporating higher or lower amount of waste, respectively. It was added chemical admixtures from two manufacturers (S and H), which were: accelerators, set retarders and superplasticizers. The experiments were organized by a factorial design 23. The measured parameters were the viscosity, the setting time, the paste and product density and the compressive strength. In this study we performed comparative analyzes of the results of compressive strength at age of 28 and 90 days and between the densities of the samples at the same ages.The compressive strength test at age of 28 days is considered a parameter essential issues related to security handling, transport and storage of cemented waste product. The results showed that the addition of accelerators improved the compressive strength of the cemented product, but presented lower values density products. (author)

354

Effect of heat treatment on bending strength, compressive strength and interfacial shear strength of carbon fiber reinforced aluminium alloys; Tanso sen`i/aruminiumu gokin fukugo zairyo no netsu shori ni yoru kaimen tsuyosa no henka to sono rikigakuteki tokusei eno eikyo  

Energy Technology Data Exchange (ETDEWEB)

Changes of matrix and interface by heat treatment are investigated for CF/Al alloy FRM (fiber reinforced material) which has been prepared on an experimental basis by pressure impregnation using 2 kinds of PAN base high elastic yarn and one kind of PAN based high elastic yarn, and the changes in the correlation among the bending strength, compression strength, and interfacial strength are investigated. The bending strength decreases rapidly from 1,200MPa to about 550MPa with the increase of the interfacial strength from 5MPa to about 25MPa and remains almost constant 450MPa with larger than 30MPa interfacial strength. The compressive strength shows no change even when the interfacial strength increases from 5MPa to 25MPa, but rapidly increases when the interfacial strength increases from 25MPa to 40MPa, and remains constant at about 1,600MPa when the interfacial strength increases higher than 40MPa. When the interfacial structure increases from 25MPa to 40MPa, the compressive strength increases from 600MPa to 900MPa. 14 refs., 7 figs., 2 tabs.

Yamada, K. [Toyo Exterior Co. Ltd., Nagano (Japan); Sekiguchi, S. [Nippon Steel Technoresearch Corp., Kawasaki (Japan); Inoue, T. [Nippon Steel Corp., Tokyo (Japan)

1997-03-15

355

Factors affecting early compressive strength of alkali activated fly ash (OPC-free concrete  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the findings of experimental research into the chief characteristics of a new type of concrete made solely with alkali activated fly ash (AAFA: i.e., free of ordinary Portland cement (OPC. The results of testing to determine specific properties of the fresh concrete and the development of its mechanical strength showed that most of the factors that affect the manufacture and final properties of Portland cement concrete (water/cement ratio, curing conditions, etc. also impact the preparation and final quality of this new material. A number of parameters specific to AAFA concrete (nature and concentration of alkali present in the system were also explored to determine their role in the setting and hardening process.Este trabajo presenta los resultados de una investigación experimental llevada a cabo para evaluar las principales características de un nuevo tipo de hormigón fabricado solamente con ceniza volante activada alcalinamente (AAFA; es decir, sin cemento Portland comercial (OPC. Los resultados de los ensayos realizados para determinar las propiedades específicas del hormigón fresco y el desarrollo de resistencias mecánicas mostraron que la mayoría de los factores que afectan al proceso de fabricación y a las propiedades finales de los hormigones de cemento Portland (relación agua/cemento, condiciones de curado, etc. también afectan a la preparación y calidad final de estos nuevos materiales. También fueron estudiados otros parámetros específicos de los hormigones de AAFA (la naturaleza y concentración del álcali presente en el sistema para determinar su papel en el proceso de fraguado y endurecimiento.

Palomo, A.

2007-08-01

356

An Assessment of the Compressive Strength of Glass Reinforced Plastic Waste Filled Concrete for Potential Applications in Construction  

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Full Text Available

Efforts were made to recycle Glass reinforced plastic (GRP waste powder in concrete products and assess its compressive strength to comply with British Standards for use in construction applications. More than 90 GRP waste-filled concrete specimens were developed using the concentration of 5%, 15%, 30% and 50% (w/w. The findings revealed that the increase in concentration of GRP waste decreased the compressive strength. However, increase in curing duration resulted in improving the compressive strength of concrete. The findings of this work pave the way for further GRP waste recycling in precast construction products for use in various applications.

 

Asokan Pappu

2010-03-01

357

Unconfined Aquifer Flow Theory - from Dupuit to present  

CERN Document Server

Analytic and semi-analytic solution are often used by researchers and practicioners to estimate aquifer parameters from unconfined aquifer pumping tests. The non-linearities associated with unconfined (i.e., water table) aquifer tests makes their analysis more complex than confined tests. Although analytical solutions for unconfined flow began in the mid-1800s with Dupuit, Thiem was possibly the first to use them to estimate aquifer parameters from pumping tests in the early 1900s. In the 1950s, Boulton developed the first transient well test solution specialized to unconfined flow. By the 1970s Neuman had developed solutions considering both primary transient storage mechanisms (confined storage and delayed yield) without non-physical fitting parameters. In the last decade, research into developing unconfined aquifer test solutions has mostly focused on explicitly coupling the aquifer with the linearized vadose zone. Despite the many advanced solution methods available, there still exists a need for realism ...

Mishra, Phoolendra K

2013-01-01

358

Concrete compressive characteristic strength analysis of pile caps with three piles / Análise da resistência característica à compressão do concreto em blocos sobre três estacas  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este trabalho tem por objetivo realizar uma análise numérica da influência da resistência característica à compressão do concreto (fck) em blocos sobre três estacas. Para tanto, foi utilizado um modelo-padrão de bloco sobre três estacas originalmente desenvolvido por Miguel [1]. A partir deste model [...] o foram realizadas variações na resistência à compressão do concreto de modo a se observar modificações no comportamento estrutural do elemento. A análise numérica é desenvolvida por meio de programa de computador baseado no MEF. Os resultados demonstraram que o aumento do fck não provocou um aumento significativo da resistência do bloco, visto que a ruína dos modelos ocorreu devido ao fendilhamento (desenvolvimento de tensões de tração perpendiculares às bielas comprimidas) e escoamento da armadura dos tirantes. Nos modelos analisados desenvolveram-se tensões de tração elevadas ao longo das bielas e na seção inferior do bloco, demonstrando que a resistência última dos blocos não é função da resistência à compressão. Abstract in english In this paper a numerical analysis of three-pile caps is developed to study the influence of concrete compressive characteristic strength in pile caps resistance capacity. A three-pile cap model derived from Miguel's [1] work was adopted. From this model, variations on the compressive characteristic [...] strength were made in order to observe modifications in its structural behavior. The numerical analysis was developed with finite element software ATENA 3D [2]. The results demonstrated that an increase in the compressive characteristic strength was not followed by a significant increment in pile cap's strength, since models' ruin were due to concrete splitting (opening cracks parallel to principal compressive stresses as a result of perpendicular tension stresses within the structure) and ties steel bars yielding. In the models analyzed high-tension stresses were developed along the struts and at the bottom of the pile cap's section, demonstrating that pile cap's ultimate resistance is not influenced by the compressive strength.

T. E.T., Buttignol; L.C., Almeida.

2013-02-01

359

In Vitro Comparison of Compressive and Tensile Strengths ofAcrylic Resins Reinforced by Silver Nanoparticles at 2% and0.2% Concentrations  

Science.gov (United States)

Background and aims. Polymethyl methacrylate, PMMA, is widely used in prosthodontics for fabrication of removable prostheses. This study was undertaken to investigate the effect of adding silver nanoparticles (AgNPs) to PMMA at 2% and 0.2% concentrations on compressive and tensile strengths of PMMA. Materials and methods. The silver nanoparticles were mixed with heat-cured acrylic resin in an amalgamator in two groups at 0.2 and 2 wt% of AgNPs. Eighteen 2×20×200-mm samples were prepared for tensile strength test, 12 samples containing silver nanoparticle and 6 samples for the control group. Another 18 cylindrical 25×38-mm samples were prepared for compressive strength test. Scanning electron microscopy was used to verify homogeneous distribution of particles. The powder was manually mixed with a resin monomer and then the mixture was properly blended. Before curing, the paste was packed into steel molds. After curing, the specimens were removed from the molds. One-way ANOVA was used for statistical analysis, followed by multiple comparison test (Scheffé’s test). Results. This study showed that the mean compressive strength of PMMA reinforced with AgNPs was significantly higher than that of the unmodified PMMA (P<0.05). It was not statistically different between the two groups reinforced with AgNPs. The tensile strength was not significantly different between the 0.2% group and unmodified PMMA and it de-creased significantly after incorporation of 2% AgNPs (P<0.05). Conclusion. Based on the results and the desirable effect of nanoparticles of silver on improvement of compressive strength of PMMA, use of this material with proper concentration in the palatal area of maxillary acrylic resin dentures is recommended. PMID:25587381

Ghaffari, Tahereh; Hamedirad, Fahimeh; Ezzati, Baharak

2014-01-01

360

Strength Behavior Study of Apples (cv. Shafi Abadi & Golab Kohanz under Compression Loading  

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Full Text Available

The mechanical properties data of fruits are important in the design of various handling, packing, storage and transportation systems. In this research some mechanical properties of two Iranian apple varieties (Golab Kohanz and Shafi Abadi were analyzed in moisture contents 86% and 84% (W.b for Golab Kohanz and Shafi Abadi varieties, respectively. Mechanical properties including rupture force and energy, deformation to rupture point, failure stress and strain, Young’s modulus (initial tangent modulus, secant modulus, tangent modulus and chard modulus, toughness and hardness were studied under compression loading using standard methods and so firmness was determined by puncture test. Average values of rupture force and energy, failure stress, failure strain, deformation, toughness and hardness were determined,57.81N, 285.88 mJ, 0.37 MPa, 31.2%, 7.77 mm,  0.06 J/cm3, 9.14 N/mm for Shafi Abadi variety, respectively. The corresponding values for Golab Kohanz variety were obtained 51.11 N, 157.51 mJ, 0.32 MPa, 23.36%, 5.6 mm, 0.04 J/cm3 and 7.79 N/mm, respectively. Initial tangent modulus, secant modulus, tangent modulus and chard modulus were obtained 0.93, 1.76, 2.27 and 2.11 MPa for Shafi Abadi variety and 0.81, 1.52, 2.08 and 2.04 MPa for Golab Kohanz variety, respectively. The firmness obtained 59.26 N for Shafi Abadi variety and corresponding value was 47.69 N for Golab Kohanz variety, respectively. According to results Shafi Abadi variety had stiffer and resisterer issue to mechanical forces than Golab Kohanz variety.

Abbas Gorji Chakespari

2010-06-01

 
 
 
 
361

Modeling Decomposition of Unconfined Rigid Polyurethane Foam  

Energy Technology Data Exchange (ETDEWEB)

The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm{sup 2} on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam which contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging.

CHU,TZE YAO; ERICKSON,KENNETH L.; HOBBS,MICHAEL L.

1999-11-01

362

Modeling decomposition of unconfined rigid polyurethane foam  

International Nuclear Information System (INIS)

The decomposition of unconfined rigid polyurethane foam has been modeled by a kinetic bond-breaking scheme describing degradation of a primary polymer and formation of a thermally stable secondary polymer. The bond-breaking scheme is resolved using percolation theory to describe evolving polymer fragments. The polymer fragments vaporize according to individual vapor pressures. Kinetic parameters for the model were obtained from Thermal Gravimetric Analysis (TGA). The chemical structure of the foam was determined from the preparation techniques and ingredients used to synthesize the foam. Scale-up effects were investigated by simulating the response of an incident heat flux of 25 W/cm(sup 2) on a partially confined 8.8-cm diameter by 15-cm long right circular cylinder of foam that contained an encapsulated component. Predictions of center, midradial, and component temperatures, as well as regression of the foam surface, were in agreement with measurements using thermocouples and X-ray imaging

363

Strength characteristics of undisturbed intermediate soil; Shizen taiseki shita chukando no kyodo tokusei  

Energy Technology Data Exchange (ETDEWEB)

As for soil design, soil is classified into two types and they are sand and clay, however, as for real soil there exist a soil between sand and clay and it does resemble neither of them and this is called in general the intermediate soil. Determination of its strength constant has been a problem. In this report, laboratory experiment using undisturbed sample, electrostatic cone penetration test (CPT) and in-situ test using dilatometer test (DMT) were carried out. From the suction test, it was understood that the residual effective stress inside the test specimen decreased sharply because the intermediate soil is effected greatly by the stress released during sampling. Therefore, strength reduction due to tension is caused and strength was evaluated little in case of unconfined compression test with no confined pressure. Accordingly, it was understood that the reconsolidation method consolidated with the in-situ confined pressure is effective to determine the strength of the intermediate soil. 14 refs., 15 figs.

Tanaka, H.; Tanaka, M.; Tsuchida, T. [Port and Harbour Research Inst., Yokosuka (Japan)

1998-03-21

364

RESIDUAL COMPRESSIVE STRENGTH OF FLY ASH BASED GLASS FIBRE REINFORCED HIGH PERFORMANCE CONCRETE SUBJECTED TO ACID ATTACK  

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Full Text Available In recent years, improvements in concrete properties have been achieved by the invention of High- Performance-Concrete (HPC. Improvements involving a combination of improved compaction, improved paste characteristics and aggregate-matrix bond, and reduced porosity are achieved through HPC. The ductility of HPC can be improved by altering its composition through the addition of glass fibers in the design mix. High- Performance-Concrete made with glass fibers inside is regarded as Glass Fiber Reinforced High Performance Concrete (GFRHPC. This paper presents the details of an experimental investigation planned to utilize fly ash in the production of Glass fibre reinforced High-Performance-Concrete (GFRHPC. The investigation examines the progressive deterioration of concrete mixtures containing various combinations of fly ash based GFRHPCmixes exposed to sulphate and chloride solutions. Acid attack tests have been conducted to measure the durability of GFRHPC. Cubes of 150X150X150 mm have been cast, cured and then kept immersed in 5%concentrated solutions of HCl, H2SO4 and MgSO4 for 30, 60 and 90 days and then tested to record the residual compressive strengths of GFRHPC produced with the fly ash mineral admixtures. The results have been analyzed and useful conclusions have been drawn.

Dr.H.Sudarsana Rao

2012-01-01

365

High pressure equation of state and ideal compressive and tensile strength of MgO single crystal: Ab-initio calculations  

Science.gov (United States)

Ab-initio total energy calculations have been carried out on MgO single crystal as a function of hydrostatic compression to determine the 0 K isotherm, which is then utilized to derive the 300 K isotherm, isentrope, and Hugoniot of MgO. The theoretical isotherm, isentrope, and Hugoniot compare well with the experimental data. The shock parameters C0 and s obtained from theoretical Hugoniot are 6.74 km/s and 1.23 as compared to the experimental values of 6.87 km/s and 1.24, respectively. Having theoretically reproduced the various experimentally measured physical quantities at ambient conditions, the calculations have been extended to determine the ideal compressive and tensile strength of MgO single crystal subjected to uniaxial compressive and tensile loading along [001] direction under two deformation conditions, namely, "uniaxial strain condition" and "uniaxial stress condition." Examination of elastic stability conditions suggests that for [001] compressive loading, the MgO single crystal will fail mechanically due to shear instability, whereas for expansion it will fail due to vanishing of tensile modulus. The ideal compressive strength under "uniaxial strain condition" and "uniaxial stress condition" is determined to be -283 GPa and -115 GPa, respectively. However, ideal tensile strength is evaluated to be 20 GPa and 11 GPa, respectively, for two loading conditions. Our results suggest that MgO single crystal will offer higher resistance against failure for compression as well as expansion along [001] direction under "uniaxial strain condition" than that for the "uniaxial stress condition."

Mukherjee, D.; Joshi, K. D.; Gupta, Satish C.

2013-06-01

366

Effects of humeral head compression taping on the isokinetic strength of the shoulder external rotator muscle in patients with rotator cuff tendinitis.  

Science.gov (United States)

[Purpose] The purpose of this study was to examine the effects of humeral head compression taping (HHCT) on the strength of the shoulder external rotator muscle in patients with rotator cuff tendinitis. [Subjects and Methods] Twenty patients with rotator cuff tendinitis were recruited. The shoulder external rotator strength was measured using a Biodex isokinetic dynamometer system. A paired t-test was performed to evaluate within-group differences in the strength of the shoulder external rotator muscle. [Results] Significantly higher shoulder external rotator peak torque and peak torque per body weight were found in the HHCT condition than in the no-taping condition. [Conclusion] HHCT may effectively increase the shoulder external rotator muscle strength in patients with rotator cuff tendinitis. PMID:25642053

Kim, Moon-Hwan; Oh, Jae-Seop

2015-01-01

367

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)

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.

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

2014-08-01

368

Compressive strength and compressive fatigue limit of conventional and high viscosity posterior resin composites Resistência a compressão e limite de fadiga compressiva de resinas compostas convencional e de alta viscosidade para dentes posteriores  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this study was to compare the compressive strengths and compressive fatigue limits of three posterior composite resins (Filtek P-60, Surefil and Prodigy Condensable and a universal restorative composite (Z-100. Cylindrical specimens (8 mm in length x 4 mm in diameter were used. The dynamic test was performed using the staircase method, and the ratio between compressive fatigue limit and compressive resistance was also calculated (n = 15. The compressive strength and compressive fatigue limit data were analyzed by Anova and Tukey’s test. The Z-100 composite demonstrated higher compression strength (307.20 MPa than Surefil (266.93 MPa and Prodigy Condensable (222.08 MPa. The resistance of Filtek P-60 (270.44 MPa was similar to the resistances of Z-100 and Surefil, while Prodigy Condensable presented the lowest compressive strength. In the compressive fatigue limit tests, Filtek P-60 demonstrated a higher value (184.20 MPa than Prodigy Condensable (155.50 MPa. Surefil (165.74 MPa and Z-100 (161.22 MPa presented limits similar to those of Filtek P-60 and Prodigy Condensable. The compressive fatigue limit/compressive strength ratio was 70.01% for Prodigy Condensable, 68.11% for Filtek P-60, 62.09% for Surefil and 52.48% for Z-100. It was concluded that the Z-100 universal composite was more sensitive to the dynamic test than the high viscosity materials.O objetivo deste estudo foi comparar a resistência à compressão e o limite de fadiga compressiva de três resinas compostas indicadas para dentes posteriores (Filtek P-60, Surefil e Prodigy Condensable e uma universal (Z-100. Corpos-de-prova cilíndricos (8 mm de altura x 4 mm de diâmetro foram usados. O teste dinâmico foi realizado usando-se o método escada e a relação entre limite de fadiga compressiva, e resistência à compressão também foi calculada (n = 15. Os dados de resistência à compressão e de limite de fadiga compressiva foram submetidos à Anova e ao teste de Tukey. O compósito Z-100 apresentou maior resistência à compressão (307,20 MPa que Surefil (266,93 MPa e Prodigy Condensable (222,08 MPa. A resistência de Filtek P-60 (270,44 MPa foi similar à de Z-100 e à de Surefil, enquanto Prodigy Condensable apresentou a menor resistência à compressão. No teste de limite de fadiga compressiva, Filtek P-60 mostrou maior valor (184,20 MPa que Prodigy Condensable (155,50 MPa. Os compósitos Surefil (165,74 MPa e Z-100 (161,22 MPa mostraram-se similares a Filtek P-60 e Prodigy Condensable. A relação limite de fadiga compressiva/resistência à compressão foi de 70,01% para Prodigy Condensable, 68,11% para Filtek P-60, 62,09% para Surefil e 52,48% para Z-100. Foi concluído que o compósito universal Z-100 foi mais sensível ao teste dinâmico que os materiais de alta viscosidade.

Letícia Brandão

2005-12-01

369

Compressive strength and compressive fatigue limit of conventional and high viscosity posterior resin composites / Resistência a compressão e limite de fadiga compressiva de resinas compostas convencional e de alta viscosidade para dentes posteriores  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo deste estudo foi comparar a resistência à compressão e o limite de fadiga compressiva de três resinas compostas indicadas para dentes posteriores (Filtek P-60, Surefil e Prodigy Condensable) e uma universal (Z-100). Corpos-de-prova cilíndricos (8 mm de altura x 4 mm de diâmetro) foram usa [...] dos. O teste dinâmico foi realizado usando-se o método escada e a relação entre limite de fadiga compressiva, e resistência à compressão também foi calculada (n = 15). Os dados de resistência à compressão e de limite de fadiga compressiva foram submetidos à Anova e ao teste de Tukey. O compósito Z-100 apresentou maior resistência à compressão (307,20 MPa) que Surefil (266,93 MPa) e Prodigy Condensable (222,08 MPa). A resistência de Filtek P-60 (270,44 MPa) foi similar à de Z-100 e à de Surefil, enquanto Prodigy Condensable apresentou a menor resistência à compressão. No teste de limite de fadiga compressiva, Filtek P-60 mostrou maior valor (184,20 MPa) que Prodigy Condensable (155,50 MPa). Os compósitos Surefil (165,74 MPa) e Z-100 (161,22 MPa) mostraram-se similares a Filtek P-60 e Prodigy Condensable. A relação limite de fadiga compressiva/resistência à compressão foi de 70,01% para Prodigy Condensable, 68,11% para Filtek P-60, 62,09% para Surefil e 52,48% para Z-100. Foi concluído que o compósito universal Z-100 foi mais sensível ao teste dinâmico que os materiais de alta viscosidade. Abstract in english The purpose of this study was to compare the compressive strengths and compressive fatigue limits of three posterior composite resins (Filtek P-60, Surefil and Prodigy Condensable) and a universal restorative composite (Z-100). Cylindrical specimens (8 mm in length x 4 mm in diameter) were used. The [...] dynamic test was performed using the staircase method, and the ratio between compressive fatigue limit and compressive resistance was also calculated (n = 15). The compressive strength and compressive fatigue limit data were analyzed by Anova and Tukey’s test. The Z-100 composite demonstrated higher compression strength (307.20 MPa) than Surefil (266.93 MPa) and Prodigy Condensable (222.08 MPa). The resistance of Filtek P-60 (270.44 MPa) was similar to the resistances of Z-100 and Surefil, while Prodigy Condensable presented the lowest compressive strength. In the compressive fatigue limit tests, Filtek P-60 demonstrated a higher value (184.20 MPa) than Prodigy Condensable (155.50 MPa). Surefil (165.74 MPa) and Z-100 (161.22 MPa) presented limits similar to those of Filtek P-60 and Prodigy Condensable. The compressive fatigue limit/compressive strength ratio was 70.01% for Prodigy Condensable, 68.11% for Filtek P-60, 62.09% for Surefil and 52.48% for Z-100. It was concluded that the Z-100 universal composite was more sensitive to the dynamic test than the high viscosity materials.

Letícia, Brandão; Gelson Luis, Adabo; Luís Geraldo, Vaz; José Roberto Cury, Saad.

2005-12-01

370

Predicting model on ultimate compressive strength of Al2O3-ZrO2 ceramic foam filter based on BP neural network  

Directory of Open Access Journals (Sweden)

Full Text Available In present study, BP neural network model was proposed for the prediction of ultimate compressive strength of Al2O3-ZrO2 ceramic foam filter prepared by centrifugal slip casting. The inputs of the BP neural network model were the applied load on the epispastic polystyrene template (F, centrifugal acceleration (v and sintering temperature (T, while the only output was the ultimate compressive strength (?. According to the registered BP model, the effects of F, v, T on ? were analyzed. The predicted results agree with the actual data within reasonable experimental error, indicating that the BP model is practically a very useful tool in property prediction and process parameter design of the Al2O3-ZrO2 ceramic foam filter prepared by centrifugal slip casting.

Yu Jingyuan

2011-08-01

371

Fly and bottom ashes from biomass combustion as cement replacing components in mortars production: rheological behaviour of the pastes and materials compression strength.  

Science.gov (United States)

In the present research mortar pastes obtained by replacing a commercial cement with the equivalent mass of 5, 10, 20 and 30 wt.% of fly ash or bottom ash from fir chips combustion, were prepared and rheologically characterized. It was observed that the presence of ash modifies their rheological behaviour with respect to the reference blend due to the presence, in the ashes, of KCl and K2SO4 which cause precipitation of gypsum and portlandite during the first hydration stages of the pastes. Hydrated materials containing 5 wt.% of ash display compression strength and absorption at 28 d of same magnitude as the reference composition; conversely, progressive increase of ash cause a continuous decline of materials performances. Conversely, samples tested after 180 d display a marked decline of compression strength, as a consequence of potassium elution and consequent alkali-silica reaction against materials under curing. PMID:21762950

Maschio, Stefano; Tonello, Gabriele; Piani, Luciano; Furlani, Erika

2011-10-01

372

Slump loss and compressive strength of concrete made with WRR and HRWR admixtures and subjected to prolonged mixing. [Water Reducing Retarders, High-Range Water Reducing  

Energy Technology Data Exchange (ETDEWEB)

The effect of four water-reducing and retarding admixtures, and three superplasticizers on the consistency (slump) of fresh concrete, was studied at 21 C and 32 C in concrete mixes, made of OPC containing 10% fly ash, and subjected to prolonged mixing for up to 180 min. The effect of such mixing on compressive strength of concrete, at the ages of 3, 7, 28 and 90 days, was also studied. It was found that the admixtures in question accelerated the rate of slump loss and at all ages, concrete compressive strength linearly increased with mixing time. The rate of slump loss, and the water demand of the concrete mixes increased within the temperature range studied.

Ravina, D.; Soroka, I. (Technion-Israel Inst. of Tech., Haifa (Israel))

1994-01-01

373

Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. OBJECTIVE: This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail...

Marcos Aurélio Bomfim da Silva; Rafael Pino Vitti; Simonides Consani; Mário Alexandre Coelho Sinhoreti; Marcelo Ferraz Mesquita; Rafael Leonardo Xediek Consani

2012-01-01

374

Effect of compressive strain holding on the low cycle fatigue strength of 2 1/4Cr-1Mo steel at elevated temperatures  

International Nuclear Information System (INIS)

The effect of compressive strain holding on the low cycle fatigue strength of 2 1/4Cr-1Mo steel was investigated at 470 deg C. Strain holding had generally no influence on the fatigue strength of 2 1/4Cr-1Mo steel, but exceptionally distinct life reduction was observed in the compressive strain holding tests at low strain range. This was considered not to be caused by the creep effects because the life reduction was not observed in the tensile strain holding tests, the value of creep damage calculated was very small and the distinct life reduction was also observed in the zero stress holding tests. Based on the observation of the oxide film, a mechanism was proposed to explain the distinct life reduction under the compressive strain holding at low strain range. The life reduction is closely related to the acceleration of fatigue crack initiation due to the oxide cracking. The same life reduction was not observed under the tensile strain holding at low strain range because the oxide which only negative strain was applied to was not cracked and at last spalled. Finally the fatigue life of the fast breeder reactor components was predicted on the basis of the presently proposed mechanism. Consequently the life under the compressive strain holding turned out to be 10 % of that of the continuous cycling. (author)

375

Unconfined versus confined speleogenetic settings: variations of solution porosity.  

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Full Text Available Speleogenesis in confined settings generates cave morphologies that differ much from those formed in unconfined settings. Cavesdeveloped in unconfined settings are characterised by broadly dendritic patterns of channels due to highly competing development.In contrast, caves originated under confined conditions tend to form two- or three-dimensional mazes with densely packed conduits.This paper illustrates variations of solution (channel porosity resulted from speleogenesis in unconfined and confined settings by theanalysis of morphometric parameters of typical cave patterns. Two samples of typical cave systems formed in the respective settingsare compared. The sample that represents unconfined speleogenesis consists of solely limestone caves, whereas gypsum cavesof this type tend to be less dendritic and more linear. The sample that represents confined speleogenesis consists of both limestoneand gypsum maze caves. The comparison shows considerable differences in average values of some parameters between thesettings. Passage network density (the ratio of the cave length to the area of the cave field, km/km2 is one order of magnitudegreater in confined settings than in unconfined (average 167.3 km/km2 versus 16.6 km/km2. Similarly, an order of magnitudedifference is observed in cave porosity (a fraction of the volume of a cave block, occupied by mapped cavities; 5.0 % versus 0.4 %.This illustrates that storage in maturely karstified confined aquifers is generally much greater than in unconfined. The average areal coverage (a fraction of the area of the cave field occupied by passages in a plan view is about 5 times greater in confined settingsthan in unconfined (29.7 % versus 6.4 %. This indicates that conduit permeability in confined aquifers is appreciably easier to targetwith drilling than the widely spaced conduits in unconfined aquifers.

Klimchouk Alexander

2006-01-01

376

Laboratory Investigation on Compressive Strength and Micro-structural Features of Foamed Concrete with Addition of Wood Ash and Silica Fume as a Cement Replacement  

Directory of Open Access Journals (Sweden)

Full Text Available Wood Ash (WA and Silica Fume (SF exhibit good cementation properties and have great potential as supplementary binder materials for the concrete production industry. This study will focus on enhancing the micro-structural formation and compressive strength of foamed concrete with the addition of WA and SF. A total of 3 mixes were prepared with the addition of WA and SF at various cement replacement levels by total binder weight. For this particular study, the combination of WA (5%, 10%, and 15% by binder weight and SF (5%, 10%, and 15% by binder weight were utilized as supplementary binder materials to produce foamed concrete mixes. As was made evident from micrographs obtained in the study, the improvement observed in the compressive strength of the foamed concrete was due to a significant densification in the microstructure of the cement paste matrix in the presence of WA and SF hybrid supplementary binders. Experimental results indicated that the combination of 15% SF and 5% WA by binder weight had a more substantial influence on the compressive strength of foamed concrete compared to the control mix. Furthermore, the addition of WA and SF significantly prolonged the setting times of the blended cement paste of the foamed concrete.

Othuman Mydin M.A.

2014-01-01

377

Blast effect from unconfined vapor cloud explosions  

Energy Technology Data Exchange (ETDEWEB)

Despite a considerable effort to predict the consequences of an unconfined vapour cloud explosion (UVCE) at a petro-chemical site, the major source of data remains the actual accidents themselves. The most has not always been made of this diagnostic information and, as an example of the type of work that can be undertaken, an analysis of the blast damage to lamp posts at Flixborough is presented in this paper combined with information from damage to other structures. This analysis provided an insight into the sequence of events. It was concluded from the calculated impulses and estimates of peak overpressures that the overpressure-time history in the near field of an UVCE is very different from that generated by the detonation of a solid explosive. The analysis is also of value in its own right since the estimated loadings can be used as a design basis for geometrically similar structures. A programme to investigate the effect of UVCE type blast waves on simple structures has been started at Buxton, as an aid to accident investigation. The facilities available for this work are described in this paper and the work planned is briefly outlined.

Roberts, A.F.; Pritchard, D.K.

1982-03-01

378

Nematode Locomotion in Unconfined and Confined Fluids  

CERN Document Server

The millimeter-long soil-dwelling nematode {\\it C. elegans} propels itself by producing undulations that propagate along its body and turns by assuming highly curved shapes. According to our recent study [PLoS ONE \\textbf{7}, e40121 (2012)] all these postures can be accurately described by a piecewise-harmonic-curvature (PHC) model. We combine this curvature-based description with highly accurate hydrodynamic bead models to evaluate the normalized velocity and turning angles for a worm swimming in an unconfined fluid and in a parallel-wall cell. We find that the worm moves twice as fast and navigates more effectively under a strong confinement, due to the large transverse-to-longitudinal resistance-coefficient ratio resulting from the wall-mediated far-field hydrodynamic coupling between body segments. We also note that the optimal swimming gait is similar to the gait observed for nematodes swimming in high-viscosity fluids. Our bead models allow us to determine the effects of confinement and finite thickness...

Bilbao, Alejandro; Vanapalli, Siva; Blawzdziewicz, Jerzy

2013-01-01

379

Nematode locomotion in unconfined and confined fluids  

Science.gov (United States)

The millimeter-long soil-dwelling nematode Caenorhabditis elegans propels itself by producing undulations that propagate along its body and turns by assuming highly curved shapes. According to our recent study [V. Padmanabhan et al., PLoS ONE 7, e40121 (2012), 10.1371/journal.pone.0040121] all these postures can be accurately described by a piecewise-harmonic-curvature model. We combine this curvature-based description with highly accurate hydrodynamic bead models to evaluate the normalized velocity and turning angles for a worm swimming in an unconfined fluid and in a parallel-wall cell. We find that the worm moves twice as fast and navigates more effectively under a strong confinement, due to the large transverse-to-longitudinal resistance-coefficient ratio resulting from the wall-mediated far-field hydrodynamic coupling between body segments. We also note that the optimal swimming gait is similar to the gait observed for nematodes swimming in high-viscosity fluids. Our bead models allow us to determine the effects of confinement and finite thickness of the body of the nematode on its locomotion. These effects are not accounted for by the classical resistive-force and slender-body theories.

Bilbao, Alejandro; Wajnryb, Eligiusz; Vanapalli, Siva A.; Blawzdziewicz, Jerzy

2013-08-01

380

Evaluation of contact strength of Li2TiO3 pebbles with different diameters  

International Nuclear Information System (INIS)

Lithium titanate (Li2TiO3) pebbles are considered to be a candidate material of the tritium breeders for fusion reactor from viewpoints of good tritium recovery, chemical stability and other good properties. The pebbles of 0.3-2 mm in diameter have been fabricated by a wet process and its characterization have been performed. Mechanical properties such as compressive strength are necessary for the design of fusion blanket packing the small pebbles. In this study, collapse loads of Li2TiO3 pebbles with different diameters were measured by an unconfined compression tester, and contact strength of these pebbles was evaluated by Hertzian contact theory. In the results, the contact strength of Li2TiO3 pebbles decreased with increasing the radius. The radial strength of Li2TiO3 pebbles was about 1.7 times large as the evaluated compression strength. On the other hand, the contact strength of Li2TiO3 pebbles was also independent of 6Li enrichment

 
 
 
 
381

Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven  

Directory of Open Access Journals (Sweden)

Full Text Available The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. OBJECTIVE: This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. MATERIAL AND METHODS: Three type IV dental stone brands were selected; elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10; G1 - room temperature (25±4ºC dried for 2 hours; G2 - room temperature dried for 24 hours; G3 - room temperature dried for 7 days and G4 - microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (p<0.05. Detailed reproduction values were reported in percentages. RESULTS: For the compressive strength test, Elite Rock and Durone IV did not present significant differences between G2 and G4, while Shera Premium did not present differences between G3 and G4. The best reproduction levels were observed for G3. CONCLUSIONS: Dental stone microwave oven drying showed a linear dimensional change similar to after room temperature drying for 24 hours and 7 days. The compressive strength of the stone dried in the microwave oven was similar to those dried at room temperature for 24 hours, with the exception of Shera Premium, which had similar results for microwave and room temperature drying for 7 days. For the microwave drying method the detail reproduction levels for samples dried at room temperature for 24 hours and 7 days were similar, except for the Durone IV.

Marcos Aurélio Bomfim da Silva

2012-10-01

382

Ground Rupturing Due to Entrapped Air/Gas in the Unconfined Zone  

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Full Text Available The sudden and large oscillation of pressure of compressed air/gas entrapped in porous medium due to the changes in the actual pore-fluid pressure, during recharge of water following intense rainfall after a prolonged period of dryness such that the rainfall intensity exceeding infiltration capacity, leads to the generation of hydo-tremors. These hydro-tremors cause ground rupturing, subsidence, developments of cracks in the building, etc. A theoretical model has been presented to estimate the successive values of compressed air/gas pressures due to the successive development of actual pore-fluid pressures and effective stresses during recharge of water of the unconfined zone during the onset of the summer monsoon of 2008 in the northern parts of India.

Manas Banerjee

2010-11-01

383

A numerical investigation into the effects of parabolic curvature on the buckling strength and behaviour of stiffened plates under in-plane compression  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The main targets of this research are mainly divided in to two parts: (1) identifying the effects of parabolic curvature on the buckling strength and behaviour of stiffened plates under in-plane compression, (2) generating practical graphs for extracting eigenvalue buckling stress of parabolic curve [...] d stiffened plate to dimensionless parameters. A parametric model for study of the problem is created. The model includes different parameters related to plate, stiffeners and also parabolic curvature. Three distinct sensitivity cases are assumed. In each sensitivity case, many different models are analysed and their buckling strengths are obtained using a finite element commercial program (ANSYS). Buckling strength and behaviour of all models with different ratios of parabolic curvature are compared to each other.

Mohammad Reza, Khedmati; Pedram, Edalat.

2010-09-01

384

Effect of activator dosage, water-to-binder-solids ratio, temperature and duration of elevated temperature curing on the compressive strength of alkali-activated fly ash cement pastes  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english In this paper the effect of sodium oxide concentration, the water-to-binder-solids ratio, temperature, and the duration of elevated temperature curing on the compressive strength of alkali-activated fly ash cement pastes was investigated. Alkali concentration varied between 3% and 15% Na2O of fly as [...] h mass. An increase in Na2O from 3% to 9% greatly improved the compressive strength of the pastes from 26.1 MPa to 50.8 MPa at 28 days. A further increase in Na2O up to 15% did not provide an increase in the strength, but a decrease was observed, as well as higher strength variation. The paste activated with 9% Na2O had the highest strength at 28 days and a low standard deviation, and 9% Na2O was thus considered as the best value in the present study. The temperature and the duration of elevated temperature curing were found to be critical factors affecting the compressive strength at early age, but their effect decreased significantly in the long term. The water-to-binder-solids ratio affected the compressive strength considerably. An increase in the water-to-binder-solids ratio of the pastes from 0.18 to 0.29 resulted in a decrease in the compressive strength from 49.3 MPa to 21.3 MPa.

J, Shekhovtsova; E P, Kearsley; M, Kovtun.

2014-10-01

385

Specimen size effects on the compressive strength and Weibull modulus of nuclear graphite of different coke particle size: IG-110 and NBG-18  

Energy Technology Data Exchange (ETDEWEB)

The effects of specimen size on the compressive strength and Weibull modulus were investigated for nuclear graphite of different coke particle sizes: IG-110 and NBG-18 (average coke particle size for IG-110: 25 ?m, NBG-18: 300 ?m). Two types of cylindrical specimens, i.e., where the diameter to length ratio was 1:2 (ASTM C 695-91 type specimen, 1:2 specimen) or 1:1 (1:1 specimen), were prepared for six diameters (3, 4, 5, 10, 15, and 20 mm) and tested at room temperature (compressive strain rate: 2.08 × 10{sup ?4} s{sup ?1}). Anisotropy was considered during specimen preparation for NBG-18. The results showed that the effects of specimen size appeared negligible for the compressive strength, but grade-dependent for the Weibull modulus. In view of specimen miniaturization, deviations from the ASTM C 695-91 specimen size requirements require an investigation into the effects of size for the grade of graphite of interest, and the specimen size effects should be considered for Weibull modulus determination.

Chi, Se-Hwan, E-mail: shchi@kaeri.re.kr [Nuclear Hydrogen Development and Demonstration Project, Korea Atomic Energy Research Institute, 1045 Daedeok Daero, Yuseong, Daejeon 305-353 (Korea, Republic of)

2013-05-15

386

Specimen size effects on the compressive strength and Weibull modulus of nuclear graphite of different coke particle size: IG-110 and NBG-18  

International Nuclear Information System (INIS)

The effects of specimen size on the compressive strength and Weibull modulus were investigated for nuclear graphite of different coke particle sizes: IG-110 and NBG-18 (average coke particle size for IG-110: 25 ?m, NBG-18: 300 ?m). Two types of cylindrical specimens, i.e., where the diameter to length ratio was 1:2 (ASTM C 695-91 type specimen, 1:2 specimen) or 1:1 (1:1 specimen), were prepared for six diameters (3, 4, 5, 10, 15, and 20 mm) and tested at room temperature (compressive strain rate: 2.08 × 10?4 s?1). Anisotropy was considered during specimen preparation for NBG-18. The results showed that the effects of specimen size appeared negligible for the compressive strength, but grade-dependent for the Weibull modulus. In view of specimen miniaturization, deviations from the ASTM C 695-91 specimen size requirements require an investigation into the effects of size for the grade of graphite of interest, and the specimen size effects should be considered for Weibull modulus determination

387

The influence of specimen capping on the results of compression strength tests of cementitious composites Influência do capeamento nos resultados do ensaio de resistência à compressão em compósitos cimentícios  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cementitious composites are commonly evaluated considering their workability, level of incorporated air, elasticity modulus and compression strength. Data from compression testing commonly present a high dispersion, which has been attributed to effects of the specimen geometry, dimensions and of the degree of material compaction, as well as to problems in the specimen end-faces, such as their parallelism, orthogonality in relation to the compression axis and surface regularity. Specimen end-f...

Augusto Cesar da Silva Bezerra; Maria Teresa Paulino Aguilar; Paulo Roberto Cetlin

2012-01-01

388

Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced b [...] y using microwave drying. OBJECTIVE: This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. MATERIAL AND METHODS: Three type IV dental stone brands were selected; elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10); G1 - room temperature (25±4ºC) dried for 2 hours; G2 - room temperature dried for 24 hours; G3 - room temperature dried for 7 days and G4 - microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (p

Marcos Aurélio Bomfim da, Silva; Rafael Pino, Vitti; Simonides, Consani; Mário Alexandre Coelho, Sinhoreti; Marcelo Ferraz, Mesquita; Rafael Leonardo Xediek, Consani.

2012-10-01

389

Uniaxial and triaxial compression tests of silicon carbide ceramics under quasi-static loading condition.  

Energy Technology Data Exchange (ETDEWEB)

To establish mechanical properties and failure criteria of silicon carbide (SiC-N) ceramics, a series of quasi-static compression tests has been completed using a high-pressure vessel and a unique sample alignment jig. This report summarizes the test methods, set-up, relevant observations, and results from the constitutive experimental efforts. Results from the uniaxial and triaxial compression tests established the failure threshold for the SiC-N ceramics in terms of stress invariants (I{sub 1} and J{sub 2}) over the range 1246 < I{sub 1} < 2405. In this range, results are fitted to the following limit function (Fossum and Brannon, 2004) {radical}J{sub 2}(MPa) = a{sub 1} - a{sub 3}e -a{sub 2}(I{sub 1}/3) + a{sub 4} I{sub 1}/3, where a{sub 1} = 10181 MPa, a{sub 2} = 4.2 x 10{sup -4}, a{sub 3} = 11372 MPa, and a{sub 4} = 1.046. Combining these quasistatic triaxial compression strength measurements with existing data at higher pressures naturally results in different values for the least-squares fit to this function, appropriate over a broader pressure range. These triaxial compression tests are significant because they constitute the first successful measurements of SiC-N compressive strength under quasistatic conditions. Having an unconfined compressive strength of {approx}3800 MPa, SiC-N has been heretofore tested only under dynamic conditions to achieve a sufficiently large load to induce failure. Obtaining reliable quasi-static strength measurements has required design of a special alignment jig and load-spreader assembly, as well as redundant gages to ensure alignment. When considered in combination with existing dynamic strength measurements, these data significantly advance the characterization of pressure-dependence of strength, which is important for penetration simulations where failed regions are often at lower pressures than intact regions.

Brannon, Rebecca Moss; Lee, Moo Yul; Bronowski, David R.

2005-02-01

390

Evaluation of Friction Coefficient and Compressive Strength of Graphite Layers of Nuclear Fuel for HTGR by Kinetic Nano-Indentation Technique  

International Nuclear Information System (INIS)

It is necessary to estimate various mechanical properties such as wear and fatigue resistances of thin coated layers of coated fuel because of the limited test conditions and dimensions. In this study, a method so called 'Kinetic Indentation Technique' was applied to evaluate wear and fatigue behaviors. The method is based on both the proportion of elastic and plastic deformation and values obtained by micro-hardness test. In this study, compressive strength and friction coefficient of graphite layers on nuclear fuel are obtained from the diagram of load-indentation depth time and vilified the values

391

Effect of sulphates in cement (containing 5% pozzolana) and in sand on the correlation between compressive strength and u.p.v. of concrete of different mixes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sulphates may be found in any of the raw materials of cement. Sand contaminated with sulphates is currently a local problem because of the difficulty in obtaining well-graded sand which could be used in concrete that has an acceptable sulphate content. In this work, the effect of sulphates in cement, with S% pozzolana, and in sand on the correlation between compressive strength and ultrasonic pulse velocity (U.P.V.) of concrete of different mixes such as 1:1.5:3, 1:2:4, and 1:3:6 is studie...

Shalal, A. R.

1990-01-01

392

Empirical relations between rock strength and physical properties in sedimentary rocks  

Energy Technology Data Exchange (ETDEWEB)

In this study, 31 empirical equations are summarized that relate unconfined compressive strength and internal friction angle of sedimentary rocks (sandstone, shale, and limestone and dolomite) to physical properties (such as velocity, modulus, and porosity). These equations can be used to estimate rock strength from parameters measurable with geophysical well logs. The ability of these equations to fit laboratory-measured strength and physical property data that were compiled from the literature is reviewed. Results from this study can be useful for petroleum industry when a range of geomechanical problems such as wellbore stability and in-situ stress measurements should be addressed without direct strength information available. While some equations work reasonably well (for example, some strength-porosity relationships for sandstone and shale), rock strength variations with individual physical property measurements scatter considerably, indicating that most of the empirical equations are not sufficiently generic to fit all the data published on rock strength and physical properties. This emphasizes the importance of local calibration before one utilizes any of the empirical relationships presented. Nonetheless, some reasonable correlations can be found between geophysical properties and rock strength that can be useful for applications related to wellbore stability where having a lower bound estimate of in situ rock strength is especially useful. (author)

Chang, Chandong; Zoback, Mark D. [Department of Geophysics, Stanford University, Palo Alto, CA 94305-2215 (United States); Khaksar, Abbas [GeoMechanics International, Inc., Perth, WA 6000 (Australia)

2006-05-16

393

Modelo teórico para a previsão da resistência à compressão da alvenaria armada / Theoretical model for predicting the compressive strength of reinforced masonry  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Neste trabalho faz-se a comparação entre diferentes modelos para se prever a resistência à compressão de prismas de alvenaria de blocos de concreto. Foram estudados experimentalmente quatro tipos diferentes de configurações de prismas, sendo cada um deles ensaiados vazios, ou seja, não grauteados, e [...] preenchidos com graute mais armaduras, denominados prismas armados. Para todos os arranjos de prismas foram registradas as suas resistências à compressão axial, deformações e modos de ruptura. Posteriormente, esses resultados foram comparados com diferentes modelos teóricos de previsão de resistência, baseados nas resistências individuais de cada material, nas suas deformações de ruptura e no efeito de cintamento introduzido pelos blocos no sistema. Entre os modelos estudados, verificou-se que os que conduziram à melhores resultados foram aqueles em que foi considerado o efeito do cintamento proporcionado pelo bloco de concreto e, ainda, uma alteração na deformação de ruptura do graute. Abstract in english This paper compares different models for predicting the compressive strength of concrete block masonry prisms. Four different prism configurations were studied experimentally, each of which was tested without grout (ungrouted prisms) and with grout and reinforcement (reinforced prisms). The axial co [...] mpressive strength, strain and failure modes of all the prism configurations were recorded. These results were then compared with different theoretical models for predicting compressive strength, based on the individual strength of each material, its break strain and the strapping effect of the blocks on the system. Among the models studied here, the best results were obtained with those that consider the strapping effect of the concrete block, as well as a change in the break strain of grout.

R. F., Silva; J. S., Camacho; R. O., Rodrigues.

2011-12-01

394

Effect of Cement Stabilized Kaolin Subgrade on Strength Properties  

Directory of Open Access Journals (Sweden)

Full Text Available Subgrade performance generally depends on the load bearing capacity of soil. This load is often affected by degree of compaction, moisture content and soil type. Poor subgrade should be avoided by removal, replace and add stabilizer agent to provide a suitable strength for subgrade. This study presents the effect of cement stabilizer on California Bearing Ratio (CBR and Unconfined Compressive Strength (UCS for kaolin clay in low traffic volume road. The test conducted includes determination of liquid limits which leads to plasticity index for tested sample. Standard proctor test have been conducted to determine the optimum moisture content and maximum dry density of kaolin clay by using soil stabilizer with 0, 7 and 13% of Ordinary Portland cement (OPC. The CBR and UCS was conduct to determine the strength of kaolin clay at optimum moisture content and 7 days curing period to obtain minimum strength of the soil. Finding of this study shows cement stabilizer effectively increase the strength of kaolin clay. 8 % of cement was found to be the optimum percentage of cement content value to be added into kaolin soil which complies with the Malaysia Public Work Department (PWD specification.

Nur Akmal Abd Karim

2014-01-01

395

The Effect of Different Mixing Methods on the Flow Rate and Compressive Strength of Mineral Trioxide Aggregate and Calcium-Enriched Mixture  

Science.gov (United States)

Introduction: Flow rate (FR) and compressive strength (CS) are important properties of endodontic biomaterials that may be affected by various mixing methods. The aim of this experimental study was to evaluate the effect of different mixing methods on these properties of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement. Materials and methods: Hand, amalgamator and ultrasonic techniques were used to mix both biomaterials. Then 0.5 mL of each mixture was placed on a glass slab to measure FR. The second glass slab (100 g) was placed on the samples and 180 sec after the initiation of mixing a 100-g force was applied on it for 10 min. After 10 min, the load was removed, and the minimum and maximum diameters of the sample disks were measured. To measure th