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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

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 properties 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) a...

Mshali, M. R.; Visser, A. T.

2012-01-01

4

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 properties 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

2012-01-01

5

Neural network prediction of unconfined compressive strength of coal fly ash-cement mixtures  

Energy Technology Data Exchange (ETDEWEB)

Prediction of mechanical properties such as unconfined compressive strength (UCS) of cement-based pastes, mortars and concrete containing coal fly ash has been done using neural network analysis (NNA) based on the Trajan Neural Network Simulator. The application of NNA has been able to identify the main variables showing an influence on UCS, and the best model to describe UCS with a root mean squared error of 6 MPa for all formulations and 5.5 MPa when formulations are restricted to the maximum addition of coal fly ash established in the European Standards (35% for cement and 55% for concrete). These results allow a good description of the experimental data for the European limits based on cement and concrete, where UCS ranges between 32.5-52.5 MPa and 12-60 MPa, respectively.

Sebastia, M.; Olmo, I.F.; Irabien, A. [University of Cantabria, Santander (Spain)

2003-08-01

6

Application of Generalized Regression Neural Networks in Predicting the Unconfined Compressive Strength of Carbonate Rocks  

Science.gov (United States)

Measuring unconfined compressive strength (UCS) using standard laboratory tests is a difficult, expensive, and time-consuming task, especially with highly fractured, highly porous, weak rock. This study aims to establish predictive models for the UCS of carbonate rocks formed in various facies and exposed in Tasonu Quarry, northeast Turkey. The objective is to effectively select the explanatory variables from among a subset of the dataset containing total porosity, effective porosity, slake durability index, and P-wave velocity in dry samples and in the solid part of samples. This was based on the adjusted determination coefficient and root-mean-square error values of different linear regression analysis combinations using all possible regression methods. A prediction model for UCS was prepared using generalized regression neural networks (GRNNs). GRNNs were preferred over feed-forward back-propagation algorithm-based neural networks because there is no problem of local minimums in GRNNs. In this study, as a result of all possible regression analyses, alternative combinations involving one, two, and three inputs were used. Through comparison of GRNN performance with that of feed-forward back-propagation algorithm-based neural networks, it is demonstrated that GRNN is a good potential candidate for prediction of the unconfined compressive strength of carbonate rocks. From an examination of other applications of UCS prediction models, it is apparent that the GRNN technique has not been used thus far in this field. This study provides a clear and practical summary of the possible impact of alternative neural network types in UCS prediction.

Ceryan, Nurcihan; Okkan, Umut; Kesimal, Ayhan

2012-11-01

7

Development of experimental correlations between indentation parameters and unconfined compressive strength (UCS) values in shale samples  

International Nuclear Information System (INIS)

Confined 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, slope, exposure time, and mud weight (Jaramillo, 2004). In last year, 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 neither 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 correspononducted in order to develop the corresponding experimental correlations. Two hundred indentation tests were also simultaneously conducted on shale fragments extracted from each plug surroundings in order to simulate the caving obtained from reservoir drilled. Results of both tests were correlated using the Minimum Square technique, seeking the best correlation that shall represent result behavior, thus obtaining two 2nd-degree polynomial correlations. Correlation coefficients of 0.6513 were determined for the (IM) - (UCS) correlation and 0.8111 for the (CTF) - (UCS) correlation. This demonstrates that the highest correlation between indentation parameters and (UCS) is obtained with the Critical Transition Force (CTF)

8

Prediction of unconfined compressive strength of cement paste containing industrial wastes.  

Science.gov (United States)

Neural network analysis was used to construct models of unconfined compressive strength (UCS) as a function of mix composition using existing data from literature studies of Portland cement containing real industrial wastes. The models were able to represent the known non-linear dependency of UCS on curing time and water content, and generalised from the literature data to find relationships between UCS and quantities of five waste types. Substantial decreases in UCS were caused by all wastes; except for EAF dust, the effect was nonlinear with the greatest decrease caused initially by approx. 12% plating sludge, 40% foundry dust, 58% other ash, and 72% MSWI fly ash by mass of dry product. It appears that the maximum waste additions used in modelling may approximate the practical limits of waste additions used in modelling may approximate the practical limits of waste addition to Portland cement, i.e., 50% plating sludge or EAF dust, 64% foundry dust, 92% other ash, and 85% MSWI fly ash by mass of dry product. The laboratory was found to be a key predictive variable and acted as a surrogate for laboratory-specific variables related to cement composition, strength and hardening class, product mixing and preparation details, laboratory conditions, and testing details. While the neural network modelling approach has been shown to be feasible, development of better models would require larger data sets with more complete information regarding laboratory-specific variables and waste composition. PMID:12781220

Stegemann, J A; Buenfeld, N R

2003-01-01

9

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.

10

Rock drillability prediction from in situ determined unconfined compressive strength of rock  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english SYNOPSIS The interaction between rock and drill bit during drilling has been modeled for many years, but a complete understanding of the phenomena occurring has yet to materialize. Successful models will allow the prediction of rate of penetration in a given environment and optimal selection of dril [...] l bit and drilling parameters, thus minimizing exploration costs. In most rock-drilling models the value of the unconfined compressive strength of the rock (UCS) is used in the predictive equations, within the concept of specific energy, and the value of UCS is the percentage of the value of the stress applied on the drilling bit in order for the bit to advance. While the exact percentage depends on the model used and it is not known with certainty, good knowledge of UCS is never-theless required before any decent prediction can be made on rate of penetration. Determination of UCS, normally done via destructive testing, requires not only the availability of sound rock core samples but also expensive testing and significant time for the test, which frequently are not available for routine drillability predictions. Hence, a multitude of methods and techniques has been proposed for estimating UCS from various indirect and/or non-destructive measurements, or combination of measurements with neural networks, such as point load index, block punch index, unit weight, and apparent porosity, water absorption by weight, sonic velocity, and Schmidt hardness. The many proposed approaches are critically reviewed and the results are compared, and what becomes apparent is that after many years, not only in mining but also in oil-well drilling, accurate indirect determination of UCS is still an elusive goal. An equation to predict UCS from sonic velocity data is suggested based on several data sets reported in the literature. Use of the specific energy equation with UCS or sonic data and utilization of drilling data allows an estimation of the efficiency of energy transfer from the bit to the rock and of the friction coefficient. Analysis of data reported in the literature, both from laboratory and field studies, has shown that this approach is sound and enables the determination of energy transfer efficiencies and friction coefficients, which for the cases studied range between 15 and 30% and 0.15 and 0.30 respectively. Thus, the suggested data analysis approach allows drillers to focus on inefficiencies and optimize drilling practices in future campaigns.

V.C, Kelessidis.

2011-06-01

11

Rock drillability prediction from in situ determined unconfined compressive strength of rock  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english SYNOPSIS The interaction between rock and drill bit during drilling has been modeled for many years, but a complete understanding of the phenomena occurring has yet to materialize. Successful models will allow the prediction of rate of penetration in a given environment and optimal selection of dril [...] l bit and drilling parameters, thus minimizing exploration costs. In most rock-drilling models the value of the unconfined compressive strength of the rock (UCS) is used in the predictive equations, within the concept of specific energy, and the value of UCS is the percentage of the value of the stress applied on the drilling bit in order for the bit to advance. While the exact percentage depends on the model used and it is not known with certainty, good knowledge of UCS is never-theless required before any decent prediction can be made on rate of penetration. Determination of UCS, normally done via destructive testing, requires not only the availability of sound rock core samples but also expensive testing and significant time for the test, which frequently are not available for routine drillability predictions. Hence, a multitude of methods and techniques has been proposed for estimating UCS from various indirect and/or non-destructive measurements, or combination of measurements with neural networks, such as point load index, block punch index, unit weight, and apparent porosity, water absorption by weight, sonic velocity, and Schmidt hardness. The many proposed approaches are critically reviewed and the results are compared, and what becomes apparent is that after many years, not only in mining but also in oil-well drilling, accurate indirect determination of UCS is still an elusive goal. An equation to predict UCS from sonic velocity data is suggested based on several data sets reported in the literature. Use of the specific energy equation with UCS or sonic data and utilization of drilling data allows an estimation of the efficiency of energy transfer from the bit to the rock and of the friction coefficient. Analysis of data reported in the literature, both from laboratory and field studies, has shown that this approach is sound and enables the determination of energy transfer efficiencies and friction coefficients, which for the cases studied range between 15 and 30% and 0.15 and 0.30 respectively. Thus, the suggested data analysis approach allows drillers to focus on inefficiencies and optimize drilling practices in future campaigns.

V.C, Kelessidis.

12

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  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, slope, 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...

Ricardo-Andrés García; Néstor-Fernando Saavedra; Zuly Calderón-Carrillo; Darwin Mateus4

2008-01-01

13

Studi Karakteristik Kuat Geser Tanah Lempung Dari Uji Unconfined Compressive Strength Dan Uji Triaksial Tak Terkonsolidasi Tak Terdrainase  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The resistance force done by soil grains toward the shear strength when it is burdened is called soil sheer strength. The parameter of the soil shear strength is needed to analyze the capacity of soil, the slope stability, and the thrust strength on the soil retaining wall. According to Mohr’s theory (1910), the condition of the collapse of divulging material is caused by the combinations of critical normal strength and shear strength. This research was conducted to know t...

Tarigan, Rasdinanta

2012-01-01

14

Rate dependent biomechanical properties of corneal stroma in unconfined compression.  

Science.gov (United States)

The corneal stroma is a highly ordered extracellular matrix and mainly responsible for the mechanical strength of the cornea. The rate dependent mechanical and rheological properties of the cornea are not completely understood and there is large variation in the reported estimates. In this work, the rate dependent mechanical behavior of the corneal stroma was investigated using experimental studies and theoretical models. Unconfined compression stress-relaxation experiments at different displacement rates and compressive strains were conducted. The unconfined compression material parameters, i.e. corneal out-of-plane modulus, in-plane modulus and permeability coefficient were determined from curve-fitting the experimental data with a transversely isotropic biphasic model. It was found that the maximum force reached during the step loading increased with both increasing magnitude and rate of the compressive strain. It was also observed that at all loading rates the in-plane Young's modulus increased with increasing strain, while the permeability coefficient decayed with increasing compressive strain. At a constant compressive strain, both the in-plane Young's modulus and the permeability coefficient increased with increasing the loading rate. Regardless of loading rates and compressive strains, a range of corneal out-of-plane modulus of 0.6 kPa to 13.8 kPa, in-plane modulus of 0.5 MPa to 4.8 MPa, and permeability coefficient of 1×10?¹? m?/N·s to 7×10?¹? m?/N·s was found. PMID:23863279

Hatami-Marbini, Hamed; Etebu, Ebitimi

2013-01-01

15

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

16

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.

17

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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, slope, 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 indentation tests were also simultaneously conducted on shale fragments extracted from each plug surroundings in order to simulate the cavings obtained from reservoir drilled. Results of both tests were correlated using the Minimum Square technique, seeking the best correlation that shall represent result behavior, thus obtaining two 2nd-degree polynomial correlations. Correlation coefficients of 0,6513 were determined for the (IM - (UCS correlation and 0,8111 for the (CTF - (UCS correlation. This demonstrates that the highest correlation between indentation parameters and (UCS is obtained with the Critical Transition Force (CTF.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 variable 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 f

Ricardo-Andrés García

2008-12-01

18

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

19

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

20

Analysis of Comparison between Unconfined and Confined Condition of Foamed Concrete Under Uni-Axial Compressive Load  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Foamed concrete has become most commercial material in construction industry. People in industries were come out with the new mix design of foamed concrete to meet the specification and the requirements needed. Approach: This is because foamed concrete has the possibility as alternative of lightweight concrete for producing intermediate strength capabilities with excellent thermal insulation, freeze-thaw resistance, high-impact resistance and good shock absorption. Results: Currently Standard test to measure the compressive strength of foamed concrete is using standard unconfined compressive test. Several research has been conduct but the compressive strength using standard unconfined compressive test not capture true behavior of foamed concrete because it just achieved only low compressive strength and sample under compression failed due to brittle collapse of the sample. This paper was analyses the comparison between standard compressive test and confined compressive test. The confinement test introduced to prevent sample from brittle collapse. Foamed concrete cylindrical sample has been investigated under the standard compressive test for hard concrete (ASTM-C39. Based on the research, samples are produced under unconfined and confined condition. Analysis has been done and the result show that under standard compressive test, the sample failed due to early crack initiation and failed. Confinement condition was increase the compressive strength but this condition influence the result. Conclusion/Recommendations: Standard test is not suitable to capture the true behavior of foamed concrete, and to prevent the sample from brittle collapse during the test, new testing method was introduced to capture the true behavior of foamed concrete which is using Quasi Static Indentation Test. This test can be used to study about the behaviour of foamed concrete before it can be implemented to its final application.

Mohd Zairul A. Abdul Rahman

2010-01-01

 
 
 
 
21

Experimental Study of the Brittle Behavior of Clay shale in Rapid Unconfined Compression  

Science.gov (United States)

The mechanical behavior of clay shales is of great interest in many branches of geo-engineering, including nuclear waste disposal, underground excavations, and deep well drilling. Observations from test galleries (Mont Terri, Switzerland and Bure, France) in these materials have shown that the rock mass response near the excavation is associated with brittle failure processes combined with bedding parallel shearing. To investigate the brittle failure characteristics of the Opalinus Clay recovered from the Mont Terri Underground Research Laboratory, a series of 19 unconfined uniaxial compression tests were performed utilizing servo-controlled testing procedures. All specimens were tested at their natural water content with loading approximately normal to the bedding. Acoustic emission (AE) measurements were utilized to help quantify stress levels associated with crack initiation and propagation. The unconfined compression strength of the tested specimens averaged 6.9 MPa. The crack initiation threshold occurred at approximately 30% of the rupture stress based on analyzing both the acoustic emission measurements and the stress-strain behavior. The crack damage threshold showed large variability and occurred at approximately 70% of the rupture stress.

Amann, Florian; Button, Edward Alan; Evans, Keith Frederick; Gischig, Valentin Samuel; Blümel, Manfred

2011-07-01

22

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

23

An experimental and theoretical analysis of unconfined compression of corneal stroma.  

Science.gov (United States)

The cornea is a transparent connective tissue with dual functions of protecting the eye (mechanical properties) and refracting the light (optical properties). Both of these properties are derived from the corneal intricate and pseudo regular extracellular matrix, the stroma. From the mechanics point of view, the corneal extracellular matrix is a hydrated structure composed of collagen fibrils, proteoglycans, and the interstitial fluid. The objective of this study was to investigate compressive biomechanical properties of the cornea using an experimental and numerical framework. The unconfined compression stress-relaxation tests were performed to measure the corneal behavior experimentally and the transversely isotropic biphasic theory was used to analyze the experimental data. It was observed that the behavior of the corneal stroma under stepwise stress-relaxation compression is similar to that of the other soft hydrated tissues and is composed of an immediate stiff response, a transient relaxation phase, and a final steady-state stage. Within the range of deformation considered in this study, maximum and equilibrium reaction stresses were linearly dependent on the compressive strain. The linear transversely isotropic biphasic model curve fitted experimental measurements with the coefficient of determination rfit(2)=0.98±0.01. The mechanical parameters of the porcine corneal stroma were calculated as a function of the engineering strain. The corneal out-of-plane modulus was almost independent of the compressive strain, the transverse Young's modulus linearly increased with increasing strain, and the permeability coefficient decayed exponentially with increasing strain. The average mechanical parameters under unconfined compression were found to be: the out-of-plane modulus E¯z=5.61KPa, the transverse Young's modulus E¯r=1.33MPa, and the permeability coefficient ?¯r=2.14×10(-14)m(4)/N.s. PMID:23664313

Hatami-Marbini, Hamed; Etebu, Ebitimi

2013-06-21

24

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

International Nuclear Information System (INIS)

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 ? ? 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 i = 0% before saturation, on specimens with a final degree of saturation of Sr ? 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

25

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

26

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

27

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

28

Acoustic emissions generated during uniaxial compressive strength tests on Lyttelton volcano rocks, Christchurch, New Zealand  

Science.gov (United States)

Earthquakes comprising the ongoing Canterbury sequence, South Island, New Zealand, have exhibited disproportionately large energy magnitude (Me) to moment magnitude (Mw) ratios (Fry and Gerstenberger, 2011). The 22 February 2011 Mw 6.3 event, for example, had an energy magnitude of 6.7 (USGS). The 22 February event may have ruptured immature faults with high apparent stress formed during the emplacement of Banks Peninsula volcanic rocks (12 Ma-6 Ma); these faults may have been further strengthened by cross-cutting intrusive rocks of the Lyttelton volcano (Fry and Gerstenberger, 2011). We measured P-wave velocity (Vp), S-wave velocity (Vs), density, elastic moduli, and unconfined compressive strength of Lyttelton volcano basalt, trachyte and rhyolite. Unconfined compressive strength (UCS) tests were conducted on specimens fitted with axial and radial strain gauges using a stress-controlled unconfined compression apparatus following ASTM standard method. UCS values range between 165 and 232 MPa for the trachyte and basalt samples; rhyolite UCS values range between 122 and 126 MPa. During UCS testing, acoustic emissions were recorded using 2 broadband AE sensors (PAC WS? 20kHz-1MHz) mounted in the end platens. AE event waveforms, magnitude-frequency relationships, and spectrograms were analyzed. Deformation of each rock type involved brittle-failure-generated AE events with broadband waveforms; numbers of AE events increased exponentially at failure. The magnitude-frequency plots of AE events display a sharp decrease in relative energy emitted at frequencies greater than 600 kHz. Quantifying absolute energy emitted at high frequencies remains challenging; we present preliminary results from experiments designed to characterize broadband frequency attenuation. Our experiments quantify the unconfined compressive strengths, elastic moduli, and characteristic AE waveforms emitted during failure of intraplate volcanic rocks comprising the Lyttelton volcano. Reference: Fry, B., and M. Gerstenberger (2011). Large apparent stresses from the Canterbury earthquakes of 2010 and 2011. Seismological Research Letters 82, 833-838.

Boulton, C.; Villeneuve, M.; Goodin, C.

2012-04-01

29

The Uniaxial Compressive Strength of Soft Rock  

Directory of Open Access Journals (Sweden)

Full Text Available Soft rock is a term that usually refers to a rock material with a uniaxial compressive strength (UCS less than 20 MPa. This low strength range might be influenced by physical characteristics, such as size, saturation, weathering and mineral content. A number of uniaxial compression tests have been conducted onto soft rock samples. The results showed that the strength reduced significantly in saturation. The reduction was also caused by weathering, the strength of distinctly weathered rocks were lower than that of partially weathered rocks. In conjunction with the uniaxial compression test, point load strength index tests, IS(50, have also been conducted in order to obtain a correlation between the UCS and the point load strength index IS(50. The results showed that the IS(50 could well be correlated with the UCS. A conversion factor of 14 is proposed for soft rock materials.

D. S. Agustawijaya

2007-01-01

30

49 CFR 238.405 - Longitudinal static compressive strength.  

Science.gov (United States)

...Longitudinal static compressive strength. 238.405 Section 238...Longitudinal static compressive strength. (a) To form an effective...longitudinal static compressive force of 2,100,000 pounds...longitudinal static compressive force of 800,000 pounds...

2010-10-01

31

Saturated-unsaturated flow to a well with storage in a compressible unconfined aquifer  

Science.gov (United States)

Mishra and Neuman (2010) developed an analytical solution for flow to a partially penetrating well of zero radius in a compressible unconfined aquifer that allows inferring its saturated and unsaturated hydraulic properties from responses recorded in the saturated and/or unsaturated zones. Their solution accounts for horizontal as well as vertical flows in each zone. It represents unsaturated zone constitutive properties in a manner that is at once mathematically tractable and sufficiently flexible to provide much improved fits to standard constitutive models. In this paper we extend the solution of [2010] to the case of a finite diameter pumping well with storage; investigate the effects of storage in the pumping well and delayed piezometer response on drawdowns in the saturated and unsaturated zones as functions of position and time; validate our solution against numerical simulations of drawdown in a synthetic aquifer having unsaturated properties described by the [1980]- [1976] model; use our solution to analyze 11 transducer-measured drawdown records from a seven-day pumping test conducted by University of Waterloo researchers at the Canadian Forces Base Borden in Ontario, Canada; validate our parameter estimates against manually-measured drawdown records in 14 other piezometers at Borden; and compare (a) our estimates of aquifer parameters with those obtained on the basis of all these records by [2008], (b) on the basis of 11 transducer-measured drawdown records by [2007], (c) our estimates of van Genuchten-Mualem parameters with those obtained on the basis of laboratory drainage data from the site by [1992], and (d) our corresponding prediction of how effective saturation varies with elevation above the initial water table under static conditions with a profile based on water contents measured in a neutron access tube at a radial distance of about 5 m from the center of the pumping well. We also use our solution to analyze 11 transducer-measured drawdown records from a 7 day pumping test conducted by University of Waterloo researchers at the Canadian Forces Base Borden in Ontario, Canada. We validate our parameter estimates against manually measured drawdown records in 14 other piezometers at Borden. We compare our estimates of aquifer parameters with those obtained on the basis of all these records by Moench (2008) and on the basis of 11 transducer-measured drawdown records by Endres et al. (2007), and we compare our estimates of van Genuchten-Mualem parameters with those obtained on the basis of laboratory drainage data from the site by Akindunni and Gillham (1992); finally, we compare our corresponding prediction of how effective saturation varies with elevation above the initial water table under static conditions with a profile based on water contents measured in a neutron access tube at a radial distance of about 5 m from the center of the pumping well.

Mishra, Phoolendra Kumar; Neuman, Shlomo P.

2011-05-01

32

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

33

(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

34

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

Directory of Open Access Journals (Sweden)

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

Sahin Zaimoglu, A.

2007-12-01

35

Compressive strength of interocclusal recording materials.  

Science.gov (United States)

Many materials are used for making interocclusal records to mount casts on dental articulators. The strength of these materials during the compressive forces encountered in the mounting process is important because any deformation will cause incorrect occlusal relationships. This investigation compared the deformation of 4 thicknesses (2 mm, 5 mm, 10 mm, 20 mm), when subjected to 25 N compressive force, of 3 interocclusal recording materials: condensation silicone, recording wax, and rubber-based polyvinylsiloxane. Significant differences were recorded for all materials of 20 mm, 10 mm and 2 mm thickness. However, there was no significant difference among the 5 mm groups. Interocclusal records should be made of a minimal thickness, using a recording material which exhibits minimal distortion during compression. PMID:11210251

Keyf, F; Altunsoy, S

2001-01-01

36

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

37

Improved forward and inverse analyses of saturated-unsaturated flow toward a well in a compressible unconfined aquifer  

Science.gov (United States)

We present an analytical solution for flow to a partially penetrating well in a compressible unconfined aquifer that allows inferring its saturated and unsaturated hydraulic properties from drawdowns recorded in the saturated and/or unsaturated zone. We improve upon a previous such solution due to Tartakovsky and Neuman (2007) by (1) adopting a more flexible representation of unsaturated zone constitutive properties and (2) allowing the unsaturated zone to have finite thickness. Both solutions account for horizontal as well as vertical flows throughout the system. We investigate the effects of unsaturated zone constitutive parameters and thickness on drawdowns in the saturated and unsaturated zones as functions of position and time; demonstrate the development of significant horizontal hydraulic gradients in the unsaturated zone in response to pumping; validate our solution against numerical simulations of drawdown in a synthetic aquifer having unsaturated properties described by the van Genuchten-Mualem constitutive model; use our solution to analyze drawdown data from a pumping test conducted by the U.S. Geological Survey at Cape Cod, Massachusetts; and compare our estimates of van Genuchten-Mualem parameters with laboratory values obtained for similar materials in the area.

Mishra, Phoolendra Kumar; Neuman, Shlomo P.

2010-07-01

38

Improved solution for saturated-unsaturated flow to a partially penetrating well in a compressible unconfined aquifer  

Science.gov (United States)

Tartakovsky and Neuman [2007] developed an analytical solution for flow to a partially penetrating well pumping at a constant rate from a compressible unconfined aquifer considering an unsaturated zone of infinite thickness. In their solution three-dimensional, axially symmetric unsaturated flow was described by a linearized version of Richards’ equation in which both relative hydraulic conductivity and water content vary exponentially with incremental capillary pressure head relative to its air entry value. Both exponential functions were characterized by a common exponent. We present an improved solution in which relative hydraulic conductivity and water content are characterized by separate parameters and the unsaturated zone has finite thickness. Our four-parameter representation of these functions is more flexible than the three-parameter version of Mathias and Butler [2006], who consider flow in the unsaturated zone to be strictly vertical and the pumping well to be fully penetrating. We investigate the effects of unsaturated zone thickness and constitutive parameters on drawdown in the unsaturated and saturated zones as functions of position and time. We then use our new solution to analyze data from synthetic and real pumping tests.

Mishra, P. K.; Neuman, S. P.

2009-12-01

39

Investigating Conversion of Endplate Chondrocytes Induced by Intermittent Cyclic Mechanical Unconfined Compression in Three-Dimensional Cultures  

Science.gov (United States)

Mechanical stimulation is known to regulate the calcification of endplate chondrocytes. The Ank protein has a strong influence on anti-calcification by transports intracellular inorganic pyrophosphate (PPi) to the extracellular matrix. It is known that TGF-?1 is able to induce Ank gene expression and protect chondrocyte calcification. Intermittent cyclic mechanical tension (ICMT) could induce calcification of endplate chondrocytes by decrease the expression of Ank gene. In this study, we investigated the relation of intermittent cyclic mechanical unconfined compression (ICMC) and Ank gene expression. We found that ICMC decreased the Ank gene expression in the endplate chondrocytes, and there was an decreased in the TGF-?1 expression after ICMC stimulation. The Ank gene expression significantly increased when treated by transforming growth factor alpha 1 (TGF-?1) in a dose-dependent manner and decreased when treated by SB431542 (ALK inhibitor) in a dose-dependent manner. Our results implicate that ICMC-induced downregulation of Ank gene expression may be regulated by TGF-?1 in end-plate chondrocytes.

Zhang, W.; Zheng, Q.; Yu, Y.F.; Deng, L.F.; Wang, H.; Liu, P.; Zhang, M.

2014-01-01

40

Behavior of High-Strength Concrete Under Sustained Compressive Stress.  

Science.gov (United States)

The behavior of plain high-strength concrete subjected to sustained compressive stress is reported. Time-dependent deformational and strength characteristics were investigated. A direct comparison was made to the behavior of normal-strength concrete subje...

A. S. Ngab

1980-01-01

 
 
 
 
41

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

42

Strength and compressibility of returned lunar soil.  

Science.gov (United States)

Two oedometer and three direct shear tests have been performed in vacuum on a 200 g sample of lunar soil from Apollo 12 (12001, 119). The compressibility data have been used to calculate bulk density and shear wave velocity versus depth on the lunar surface. The shear wave velocity was found to increase approximately with the one-fourth power of the depth, and the results suggest that the Apollo 14 Active Seismic Experiment may not have detected the Fra Mauro formation at a depth of 8.5 m, but only naturally consolidated lunar soil. The shear data indicate that the strength of the lunar soil sample is about 65% that of a ground basalt simulant at the same void ratio.

Carrier, W. D., III; Bromwell, L. G.; Martin, R. T.

1972-01-01

43

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

44

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

Science.gov (United States)

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

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

45

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

46

Studies of fiber-matrix adhesion on compression strength  

Science.gov (United States)

A study was initiated on the effect of the matrix polymer and the fiber matrix bond strength of carbon fiber polymer matrix composites. The work includes tests with micro-composites, single ply composites, laminates, and multi-axial loaded cylinders. The results obtained thus far indicate that weak fiber-matrix adhesion dramatically reduces 0 degree compression strength. Evidence is also presented that the flaws in the carbon fiber that govern compression strength differ from those that determine fiber tensile strength. Examination of post-failure damage in the single ply tests indicates kink banding at the crack tip.

Bascom, Willard D.; Nairn, John A.; Boll, D. J.

1991-01-01

47

Compressive strength and rheology of environmentally-friendly binders  

Directory of Open Access Journals (Sweden)

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

Juan Manuel Lizarazo Marriaga

2010-07-01

48

Compressive strength of fiber-reinforced composite materials  

Science.gov (United States)

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

Davis, J. G., Jr.

1975-01-01

49

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

50

Transverse Compression Strength of Heavily Reinforced Concrete.  

Science.gov (United States)

The static and fatigue strength of 150 x 150 x 450 mm concrete prisms with heavy concentrations of reinforcement placed transverse to the direction of applied load is compared to the strength of plain concrete prisms. Of eight patterns tested, only one is...

R. G. Anderson

1981-01-01

51

Intelligent Estimation of Compressive Strength of the Pavement Layers Stabilized by the Combination of Bitumen Emulsion and Cement  

Directory of Open Access Journals (Sweden)

Full Text Available The Application of the different types of additive materials such as lime, cement bitumen and the combination of them are considered as a main issue by the relating experts. In order to promote the bearing capacity of road, these materials, individually, or with the attendance of other materials add to sub base layers. During the recent years, road builders have been considering the application of the combination of bitumen emulsion and cement due to the emergence of the modern equipments and machineries in transportation engineering which have been led to the rapid construction of roads and a uniform combination with the suitable compactness properties in soil stabilization too. The compressive strength which can be determined by the Unconfined Compressive Strength (UCS test is one of the most important factors to control the quality of the stabilized materials using bitumen emulsion and cement and also in order to design them much efficiently. Besides, it is necessary to use an analytical method because the laboratory tests are very expensive and in some cases are not available especially in the projects constructing in the remote areas and also the strong need for controlling the obtained results from the insitu tests. In this study, the application of the inelegant neural network is investigated to estimate the 28 days compressive strength of the samples built from the stabilized materials by the combination of bitumen emulsion and cement. The obtained results show that; artificial neural network is very capable in predicting the 28 days compressive strength.

Mehrdad Aryafar

2008-01-01

52

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

53

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

54

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

55

Removal of surface loop from stitched composites can improve compression and compression-after-impact strengths  

Science.gov (United States)

Stitching through-the-thickness (TTT) of composite materials produces a surface loop of yarn between successive penetrations. The surface loop is pressed into the surface layers of the composite material during the curing of the laminate, kinking the in-plane fibers near the surface of the material. The compression strength and compression-after-impact (CAI) strengths of carbon-epoxy specimens were measured with and without the surface loop. Removal of the surface loop had no influence on failure mode or failure mechanism, but did significantly increase the compression and CAI strengths.

Farley, Gary L.; Dickinson, Larry C.

1992-01-01

56

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

57

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

58

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

59

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)

60

Strength Tests on Paper Cylinder in Compression, Bending and Shear  

Science.gov (United States)

Static tests on paper cylinders were conducted at the Langley Memorial Aeronautical Laboratory at Langley Field, Virginia, to obtain qualitative information in connection with a study of the strength of stressed-skin fuselages. The effects of radius-thickness ratio and bulkhead spacing were investigated with the cylinders in compression, bending, combined bending and shear, and torsion.

Rhodes, Richard V; Lundquist, Eugene E

1931-01-01

 
 
 
 
61

Cement paste compressive strength estimation using nondestructive microwave reflectometry  

Science.gov (United States)

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

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

1994-09-01

62

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

63

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

64

Estimating rock compressive strength from Rock Abrasion Tool (RAT) grinds  

Science.gov (United States)

Each Mars Exploration Rover carries a Rock Abrasion Tool (RAT) whose intended use was to abrade the outer surfaces of rocks to expose more pristine material. Motor currents drawn by the RAT motors are related to the strength and hardness of rock surfaces undergoing abrasion, and these data can be used to infer more about a target rock's physical properties. However, no calibration of the RAT exists. Here, we attempt to derive an empirical correlation using an assemblage of terrestrial rocks and apply this correlation to data returned by the rover Spirit. The results demonstrate a positive correlation between rock strength and RAT grind energy for rocks with compressive strengths less than about 150 MPa, a category that includes all but the strongest intact rocks. Applying this correlation to rocks abraded by Spirit's RAT, the results indicate a large divide in strength between more competent basaltic rocks encountered in the plains of Gusev crater (Adirondack-class rocks) and the weaker variety of rock types measured in the Columbia Hills. Adirondack-class rocks have estimated compressive strengths in the range of 70-130 MPa and are significantly less strong than fresh terrestrial basalts; this may be indicative of a degree of weathering-induced weakening. Rock types in the Columbia Hills (Wishstone, Watchtower, Clovis, and Peace class) all have compressive strengths <50 MPa and are consistent with impactites or volcanoclastic materials. In general, when considered alongside chemical, spectral, and rock textural data, these inferred compressive strength results help inform our understanding of rock origins and modification history.

Thomson, B. J.; Bridges, N. T.; Cohen, J.; Hurowitz, J. A.; Lennon, A.; Paulsen, G.; Zacny, K.

2013-06-01

65

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

66

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

67

EFFECT OF HISTOMORPHOMETRIC PARAMETERS ON COMPRESSION STRENGTH OF VERTEBRAL BODIES  

Directory of Open Access Journals (Sweden)

Full Text Available Computer aided image analysis was applied to elaborate an automatic method of histomorphometric analysis of trabecular bone samples. Transverse sections of decalcified vertebral bodies were examined using optical microscopy and digital image acquisition system. Further analysis was done by means of a general purpose image analysis package. The same algorithm was applied to all the images tested, thus enabling obtainment of objective and repeatable results. High efficiency in measurements and evaluation of parameters not accessible for manual methods makes this method an interesting alternative for classical histomorphometric analysis. The results obtained demonstrated that assessment of bone mineral density is not sufficient for evaluation of compression strength of vertebral bodies. In contrast, mechanical properties correlate well with histomorphometric parameters. As a consequence it was postulated that compression strength of vertebral bodies is controlled by trabecular structure rather than bone mineral density.

Artur Gadek

2011-05-01

68

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

69

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

70

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

71

Compressive strength of glass ionomer cements using different specimen dimensions.  

Science.gov (United States)

The purpose of this study was to evaluate the compressive strength of two glass ionomer cements, a conventional one (Vitro Fil - DFL) and a resin-modified material (Vitro Fil LC - DFL), using two test specimen dimensions: One with 6 mm in height and 4 mm in diameter and the other with 12 mm in height and 6 mm in diameter, according to the ISO 7489:1986 specification and the ANSI/ADA Specification No. 66 for Dental Glass Ionomer Cement, respectively. Ten specimens were fabricated with each material and for each size, in a total of 40 specimens. They were stored in distilled water for 24 hours and then subjected to a compressive strength test in a universal testing machine (EMIC), at a crosshead speed of 0.5 mm/min. The data were statistically analyzed using the Kruskal-Wallis test (5%). Mean compressive strength values (MPa) were: 54.00 +/- 6.6 and 105.10 +/- 17.3 for the 12 mm x 6 mm sample using Vitro Fil and Vitro Fil LC, respectively, and 46.00 +/- 3.8 and 91.10 +/- 8.2 for the 6 mm x 4 mm sample using Vitro Fil and Vitro Fil LC, respectively. The resin-modified glass ionomer cement obtained the best results, irrespective of specimen dimensions. For both glass ionomer materials, the 12 mm x 6 mm matrix led to higher compressive strength results than the 6 mm x 4 mm matrix. A higher variability in results was observed when the glass ionomer cements were used in the larger matrices. PMID:17710284

Mallmann, André; Ataíde, Jane Clei Oliveira; Amoedo, Rosa; Rocha, Paulo Vicente; Jacques, Letícia Borges

2007-01-01

72

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

73

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

74

Flow strength of tantalum under ramp compression to 250?GPa  

Energy Technology Data Exchange (ETDEWEB)

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 10{sup 5}?s{sup ?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.

Brown, J. L.; Alexander, C. S.; Asay, J. R.; Dolan, D. H. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Vogler, T. J. [Sandia National Laboratories, Livermore, California 94450 (United States); Belof, J. L. [Lawrence Livermore National Laboratories, Livermore, California 94550 (United States)

2014-01-28

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Flow strength of tantalum under ramp compression to 250-GPa  

Science.gov (United States)

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.

Brown, J. L.; Alexander, C. S.; Asay, J. R.; Vogler, T. J.; Dolan, D. H.; Belof, J. L.

2014-01-01

76

Toroidal, compression and vortical dipole strengths in 124Sn  

International Nuclear Information System (INIS)

The toroidal, compression and vortical dipole strength functions in semi-magic 124Sn (and partly in doubly magic 100,132Sn) are analyzed within the random-phase-approximation method with the SkT6, SkI3, SLy6, SV-bas and SkM* Skyrme forces. The isoscalar (T = 0), isovector (T = 1) and electromagnetic (‘elm’) channels are considered. Both convection jc and magnetization jm nuclear currents are taken into account. The calculations basically confirm the previous results obtained for 208Pb with the force SLy6. In particular, it is shown that the vortical and toroidal strengths are dominated by jc in the T = 0 channel and by jm in the T = 1 and ‘elm’ channels. The compression strength is always determined by jc. It is also shown that the ‘elm’ strength (relevant for the (e,e?) reaction) is very similar to the T = 1 one. The toroidal mode resides in the region of the pygmy resonance. So, perhaps, this region embraces both irrotational (pygmy) and vortical (toroidal) flows. (paper)

77

Toroidal, compression, and vortical dipole strengths in 124Sn  

CERN Document Server

The toroidal, compression and vortical dipole strength functions in semi-magic $^{124}$Sn (and partly in doubly-magic $^{100,132}$Sn) are analyzed within the random-phase-approximation method with the SkT6, SkI3, SLy6, SV-bas, and SkM* Skyrme forces. The isoscalar (T=0), isovector (T=1), and electromagnetic ('elm') channels are considered. Both convection $j_c$ and magnetization $j_m$ nuclear currents are taken into account. The calculations basically confirm the previous results obtained for $^{208}$Pb with the force SLy6. In particular, it is shown that the vortical and toroidal strengths are dominated by $j_c$ in T=0 channel and by $j_m$ in T=1 and 'elm' channels. The compression strength is always determined by $j_c$. It is also shown that the 'elm' strength (relevant for (e,e') reaction) is very similar to T=1 one. The toroidal mode resides in the region of the pygmy resonance. So, perhaps, this region embraces both irrotational (pygmy) and vortical (toroidal) flows.

Kvasil, J; Repko, A; Kleinig, W; Reinhard, P -G; Iudice, N Lo

2012-01-01

78

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

79

INTRA-RING COMPRESSION STRENGTH OF LOW DENSITY HARDWOODS  

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Full Text Available 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 universally 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

2006-01-01

80

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.

 
 
 
 
81

Ultra-porous titanium oxide scaffold with high compressive strength  

Science.gov (United States)

Highly porous and well interconnected titanium dioxide (TiO2) scaffolds with compressive strength above 2.5 MPa were fabricated without compromising the desired pore architectural characteristics, such as high porosity, appropriate pore size, surface-to-volume ratio, and interconnectivity. Processing parameters and pore architectural characteristics were investigated in order to identify the key processing steps and morphological properties that contributed to the enhanced strength of the scaffolds. Cleaning of the TiO2 raw powder removed phosphates but introduced sodium into the powder, which was suggested to decrease the slurry stability. Strong correlation was found between compressive strength and both replication times and solid content in the ceramic slurry. Increase in the solid content resulted in more favourable sponge loading, which was achieved due to the more suitable rheological properties of the ceramic slurry. Repeated replication process induced only negligible changes in the pore architectural parameters indicating a reduced flaw size in the scaffold struts. The fabricated TiO2 scaffolds show great promise as load-bearing bone scaffolds for applications where moderate mechanical support is required. PMID:20711636

Tiainen, Hanna; Lyngstadaas, S. Petter; Ellingsen, Jan Eirik

2010-01-01

82

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 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

83

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

84

Strength and stiffness of thermally rectified eucalyptus wood under compression  

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Full Text Available 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 furnace 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

2013-01-01

85

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

86

Investigation of Salinity Effect on Compressive Strength of Reinforced Concrete  

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Full Text Available This study adopt laboratory controlled experiment approach, in order to induce the worst scenario of concrete mix and determine the consequent effect on reinforced concrete element; a mix ratio of 1:3:6 was adopted for the experiment. Reinforced concrete elements were cast using both lagoon and ocean water while fresh water was used as a control experiment. These samples were buried at a depth of 1.5m below the ocean and lagoon bed soil characteristics and observed for a period of 150 days. Both the ocean and the lagoon samples increases in compressive strength from 10.65N/mm2 and 10.57N/mm2 on 7th day to 17.05N/mm2 and 18.04N/mm2 on the 21st day respectively as against the 14.20N/mm2 on 7th day to 17.05N/mm2 and 18.04N/mm2 fresh water sample. On 14th day fresh water sample has 17.48N/mm2 as against 12.10N/mm2 and 12.55N/mm2 recorded for both ocean and lagoon water samples. The findings revealed that concrete sample cast and cured with fresh water gained appreciable compressive strength over 150 days period while sample cast and cured with ocean and lagoon water slowly increase in strength but lower when compared with fresh water reinforced concrete element. Therefore the study recommended that a rich mix other than 1:3:6 and 1:3:5 be strictly enforced on construction sites for concrete under saline attack, increase concrete cover be used for protection against corrosion, and that non destructive test be carried out on all formworks under vertical loads like slabs and beams before they are stripped.

Akinsola Olufemi Emmanuel

2012-05-01

87

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

88

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.

2014-01-01

89

Influence of pore structure on compressive strength of cement mortar.  

Science.gov (United States)

This paper describes an experimental investigation into the pore structure of cement mortar using mercury porosimeter. Ordinary Portland cement, manufactured sand, and natural sand were used. The porosity of the manufactured sand mortar is higher than that of natural sand at the same mix proportion; on the contrary, the probable pore size and threshold radius of manufactured sand mortar are finer. Besides, the probable pore size and threshold radius increased with increasing water to cement ratio and sand to cement ratio. In addition, the existing models of pore size distribution of cement-based materials have been reviewed and compared with test results in this paper. Finally, the extended Bhattacharjee model was built to examine the relationship between compressive strength and pore structure. PMID:24757414

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

2014-01-01

90

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

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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

91

Test results and model for the residual compressive strength of concrete after a fire  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An investigation into temperature induced degradation of the compressive strength of concrete including that under cooling phase is carried out. The paper gathers and reviews a considerable amount of test data, considering the influence of different test parameters such as initial compressive strength, aggregate type, cooling regime and specimen shape. It is found that the compressive strength of concrete at high temperature is in accordance with the model proposed in the Eurocodes for calcar...

Li, Yi-hai; Franssen, Jean-marc

2011-01-01

92

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; Jensen, Ole Mejlhede

2010-01-01

93

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

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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

94

Compressive and diametral tensile strength of glass ionomer cements.  

Science.gov (United States)

The aim of this study was to compare, in different periods of time, the compressive and diametral tensile strength of a traditional high viscous glass ionomer cement: Fuji IX (GC Corporation), with two new Brazilian GIC's: Vitro-Molar (DFL) and Bioglass R (Biodinamica), all indicated for the Atraumatic Restorative Treatment (ART) technique. Fifteen disk specimens (6.0mm diameter x 3.0mm height) for the diametral tensile strength (DTS) test and fifteen cylindrical specimens (6.0mm diameter x 12.0mm height) for the compressive strength (CS) test were made of each GIC. Specimens were stored in deionized water at 37º C and 100% of humidity in a stove until testing. Five specimens of each GIC were submitted to CS and DTS test in each period, namely 1 hour, 24 hours and 7 days. The specimens were tested in a testing machine (Emic) at a crosshead speed of 1.0mm/min for CS and 0.5mm/min for the DTS test until failure occurred. The data were submitted to two-way ANOVA and Tukey tests (alpha=0.05). The mean CS values ranged from 42.03 to 155.47MPa and means DTS from 5.54 to 13.72 MPa, with test periods from 1h to 7 days. The CS and DTS tests showed no statistically significant difference between Fuji IX and Vitro Molar, except for CS test at 1-hour period. Bioglass R had lowest mean value for CS of the cements tested. In DTS test Bioglass R presented no statistically significant differences when compared with all others tested GICs at 1-hour period and Bioglass R presented no difference at 24-hour and 7-day periods when compared to Vitro-Molar. Further studies to investigate other physical properties such as fracture toughness and wear resistance, as well as chemical composition and biocompatibility, are now needed to better understand the properties of these new Brazilian GIC's. PMID:20976409

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

2004-12-01

95

Compressibility and strength of nanocrystalline tungsten boride under compression to 60 GPa  

International Nuclear Information System (INIS)

The compression behavior and stress state of nanocrystalline tungsten boride (WB) were investigated using radial x-ray diffraction (RXRD) in a diamond-anvil cell under non-hydrostatic compression up to 60.4 GPa. The compression properties and stress state are analyzed using lattice strain theory. Experiments were conducted at beamline X17C of the National Synchrotron Light Source. The radial x-ray diffraction data yield a bulk modulus that is qualitatively consistent with density functional theory calculations and demonstrate that WB is a highly incompressible material. A maximum differential stress, t, of about 14 GPa can be supported by nanocrystalline WB at the highest pressure. This corresponds to about 5% of the shear modulus, G, which is smaller than the values of t/G (?8%-10%) observed for BC2N, B6O, TiB2, and ?-Si3N4 at high pressures. Thus, while WB is highly incompressible, its strength is relatively low at high pressures compared to other hard ceramics.

96

Rock physical interpretation of the compressive strength-seismic velocity relationship for sedimentary rocks  

Science.gov (United States)

Estimating the strength, especially compressive strength, of rocks is one of the major problems in many civil engineering applications. Compressive strength of a rock is usually measured in a laboratory test of rock specimens obtained in boreholes drilled in the investigation site. If seismic velocity can be used for estimating rock strength, the seismic method can be employed effectively for profiling strength of a large rock mass because it is capable of determining subsurface seismic properties over a large area. Rock strength is often estimated from seismic velocity using correlations between data of each property, measured in the specific rock mass, or by using existing empirical relations. These techniques, however, have problems in accuracy and reliability of their estimates, because the correlations between measured data generally are made with a small number of data, and empirical relations are restricted for applicable rock types. In this study, a rock physics model is studied to estimate the compressive strength from seismic velocity more accurately and reliably. The confined compressive strength-seismic velocity relationship is modelled by combining two effective-medium models for (1) the confined compressive strength v. porosity and (2) seismic velocity v. porosity. The model is applied to S-wave velocity log data in soft sedimentary rocks, and the model predictions are compared with confined compressive strength, measured with the triaxial compression test on rock cores sampled in the same borehole as that used for the velocity logging. The model is also applied to ultrasonic P-wave velocity and confined compressive strength data measured in the laboratory, using core samples of sedimentary rocks collected from various sites in Japan. Good agreement between model-calculated and measured data in the confined compressive strength-seismic velocity relationships in these cases reveals that the confined compressive strength can be estimated from seismic velocity using a rock physics model.

Takahashi, Toru; Tanaka, Soichi

2013-01-01

97

Strength of thin laminated polyimide/S2 glass under simultaneous face compression and interlaminar shear  

International Nuclear Information System (INIS)

The experiment was performed to determine the strength of laminated organic insulators loaded simultaneously in face compression and interlaminar shear. Thin disks of polyimide/S2 glass (PS2) laminate were compressed perpendicular to the surface and loaded in face torsion at room temperature and 77 K. The interlaminar shear strength was determined as a function of face pressure

98

Effect of Copper Content on Compressive Strength and Microstructure of Dental Amalgams  

Directory of Open Access Journals (Sweden)

Full Text Available The main goal of this research is to investigate the effect of copper on compressive strength of dental amalgam. For this purpose amalgam capsules with two different content of copper were used. Cylindrical samples with diameter to height ratio 1 to 2, were prepared via molding method. To evaluate the role of copper element on compressive strength, com-pression test was done at different strain rates i.e. 0.02, 0.2, 0.4 and 2 min–1. The results and microscopic evaluations showed that an increase in copper content in amalgam caused to eliminate gamma2 phase and leaded to promote compressive strength.

Seyed Abdolkarim Sajjadi

2012-03-01

99

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.

2014-08-01

100

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.

 
 
 
 
101

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

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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

102

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

103

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

104

Compression Strength of Fir and Beech Wood Modified by Citric Acid  

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Full Text Available 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 compression strength of wood. Fir wood (Abies alba Mill. and beech wood (Fagus sylvatica L. were impregnated by citric acid with sodium-dihydrogen-hypophosphite (NaH2PO2 as a catalyst. Part of the impregnated samples together with control samples were cured at the temperature of 140 °C for 10 hours and the remaining samples were cured in microwaves for 35 minutes. The average compression strength parallel to the grain of wood modifi ed by CA, using different regimes of curing, was compared to the strength of unmodifi ed wood. The average compression strength parallel to the grain of wood was retained after modification. In the case of fir wood, the average compression strength was even improved after modification. The results indicate that wood modified by citric acid may be considered for the purposes where compression strength properties are equally important as improved durability and dimensional stability of wood.

Bogoslav Šefc

2012-03-01

105

The estimation of compressive strength of normal and recycled aggregate concrete  

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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

106

Evaluation of the size effect on the compressive strength test in cement waste form  

International Nuclear Information System (INIS)

It is difficult to carry out the evaluation of the integrity and safety of radioactive waste forms produced in the nuclear facilities with a size of 200L real waste form. Therefore waste form's characterization, consisting of the compressive strength test, the leaching/immersion test, the thermal cycling test, and the radiation resistance test, is performed by using small size specimens extracted from waste form. The compressive strength, one of the most important items to evaluate structural safety of waste form, highly depends on the test conditions such as the shape and size of specimen and the loading rate of compression machine. According to the destructive mechanism with compression it is known that the destruction breaks out because of the concentration of the high stress in the vicinity of a spot existing non-homogeneity such a defect and crack inside the specimen. In this work, the compressive strengths were measured with the variation of the specimen size and the loading rate. And then, the compressive strengths were evaluated for the variation of the above parameters to be affected to the compressive strength. It was also compared with the compressive strength before and after thermal cycling test

107

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

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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

108

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

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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

109

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

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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

110

Fracture Energy of High-Strength Concrete in Compression  

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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

1989-01-01

111

Multiple Regression Model for Compressive Strength Prediction of High Performance Concrete  

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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

112

Determine the compressive strength of calcium silicate bricks by combined nondestructive method.  

Science.gov (United States)

The paper deals with the application of combined nondestructive method for assessment of compressive strength of calcium silicate bricks. In this case, it is a combination of the rebound hammer method and ultrasonic pulse method. Calibration relationships for determining compressive strength of calcium silicate bricks obtained from nondestructive parameter testing for the combined method as well as for the L-type Schmidt rebound hammer and ultrasonic pulse method are quoted here. Calibration relationships are known for their close correlation and are applicable in practice. The highest correlation between parameters from nondestructive measurement and predicted compressive strength is obtained using the SonReb combined nondestructive method. Combined nondestructive SonReb method was proved applicable for determination of compressive strength of calcium silicate bricks at checking tests in a production plant and for evaluation of bricks built in existing masonry structures. PMID:25276864

Brozovsky, Jiri

2014-01-01

113

Producer's Risk Associated with Concrete Compressive Strength Acceptance Criteria of IS456-2000  

Science.gov (United States)

Realising that acceptance criteria for the compressive strength of concrete is important for achieving safety and economy in construction, IS 456:2000, has recommended suitable criteria. The criteria recommended in IS 456:2000 are based on statistical sampling theory. However, the risk associated with the acceptance criteria is not known. In this work, an attempt has been made to examine the acceptance criteria for the compressive strength of concrete specified in IS 456:2000 through statistical sampling theory in conjunction with Monte Carlo simulation technique. From the results obtained, it is noted that the risk associated with the acceptance criteria for the compressive strength of concrete specified in IS 456:2000 depends on the standard deviation of compressive strength. Based on this observation, a method has been presented to achieve uniform value of producer's risk through the use of a factor.

Balaji Rao, K.; Anoop, M. B.; Iyer, Nagesh R.

2013-11-01

114

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

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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

115

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

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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

116

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

Science.gov (United States)

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

Davis, J. G., Jr.

1974-01-01

117

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

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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

118

Compression Strength of Fir and Beech Wood Modified by Citric Acid  

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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

119

Compressive Strength and Setting Time of MTA and Portland Cement Associated with Different Radiopacifying Agents  

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Objective. The aim of this study was to evaluate the compressive strength and setting time of MTA and Portland cement (PC) associated with bismuth oxide (BO), zirconium oxide (ZO), calcium tungstate (CT), and strontium carbonate (SC). Methods. For the compressive strength test, specimens were evaluated in an EMIC DL 2000 apparatus at 0.5?mm/min speed. For evaluation of setting time, each material was analyzed using Gilmore-type needles. The statistical analysis was performed with ANOVA and ...

Tanomaru-filho, Mario; Morales, Vanessa; Da Silva, Guilherme F.; Bosso, Roberta; Reis, Jose? M. S. N.; Duarte, Marco A. H.; Guerreiro-tanomaru, Juliane M.

2012-01-01

120

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

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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

 
 
 
 
121

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

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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

122

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

123

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

124

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

DEFF Research Database (Denmark)

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

Jensen, Find MØlholt

2003-01-01

125

An evalution of compressive strength of newer nanocomposite: An in vitro study  

Science.gov (United States)

Aim: The purpose of the study is to assess and compare compressive strength of newer nanocomposites (FiltekZ350, Ceram X Mono, Ceram X Duo) with microhybrid (Tetric Ceram) and to compare difference in compressive strength of newer nanocomposites. Materials and Methods: Forty eight specimens of composite were fabricated using customized biparpite brass mold measuring 5mm x 5mm and were grouped with twelve specimens in each Group I : Tetric Ceram, Group II: Filtek Z 350, Group III : Ceram X Mono, Group IV : Ceram X Duo. Composite resins are placed in cylindrical recesses and covered with mylar strip and are cured using QHL light curing unit. Compressive strength is evaluated using Instron machine. Results are statistically analyzed using One way Anova and Student t test. Analysis demonstrated that nanocomposites have better compressive strength than micro hybrid (P<0.001). Results: Within the limitations of the study, it can be concluded that nanocomposites have better compressive strength than microhybrid composite and nanocomposite showed optimal compressive strength of 312 - 417 Mpa. PMID:21691503

Hegde, Mithra N; Hegde, Priyadarshini; Bhandary, Shruthi; Deepika, K

2011-01-01

126

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

127

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.

HØskuldsson, Agnar

2008-01-01

128

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.

HØskuldsson, Agnar

2010-01-01

129

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

130

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

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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

131

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.

132

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

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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

133

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 strength increased with the real density.

134

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

Directory of Open Access Journals (Sweden)

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

135

Estimation of hardness and compressive strength of SP 100 aluminum powder epoxy  

Energy Technology Data Exchange (ETDEWEB)

In this study, we performed experimental tests on five SP 100 aluminum powder epoxy specimens with several after curing conditions in order to estimate their hardness with temperature and compressive strength. In the surface hardness test, it was found that the higher the after curing temperature, the higher was the hardness. In particular, it was found that the hardness of the specimens in cases 3 and 4 was much higher than in the other cases. In addition, in the compression tests carried out to evaluate the compressive strength, it was found that the specimens showed relatively similar stiffness and strength with after curing, and specimens with no after curing showed compression stress strain curves similar to those of thermoplastic resins.

Han, Jeong Young [Pusan National Univ., Busan (Korea, Republic of); Kim, Myung Hun [Korea Institute of Footwear and Leather Technology, Busan (Korea, Republic of); Kang, Sung Soo [Jeonju Univ., Jeonju (Korea, Republic of)

2012-09-15

136

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

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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

137

Compressive Strength of Volcanic Ash/Ordinary Portland Cement Laterized Concrete  

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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

138

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

139

Variations in Compressive Strength of Geopolymer due to the CaO Added Fly Ash  

Science.gov (United States)

Recently, geopolymer has been a noteworthy material which can be used as a replacement for portland cement. The mechanical characteristics and consistency of the geopolymer are strongly affected by its chemical components of fly ash. The variations in compressive strength of geopolymer due to the CaO added fly ash were investigated in this paper. The compressive strengths of geopolymer were increased with an increase in the curing period, and the characteristics changed from the one of plastic soil material to brittle material such as concrete, regardless of CaO content. Also, the results of compressive strength and modulus of deformation showed their maximum value in the case of 8-10% CaO content. From this result, the maximum characteristics of the strengths were assumed to be exerted in case which the water draining process of geopolymer was balanced with the water absorbing process of additional CaO.

Zhao, Yuqing; Koumoto, Tatsuya; Kondo, Fumiyoshi

140

The estimation of compressive strength of normal and recycled aggregate concrete  

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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

 
 
 
 
141

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

142

Permeability, porosity and compressive strength of self-compacting concrete  

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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

143

INTRA-RING COMPRESSION STRENGTH OF LOW DENSITY HARDWOODS  

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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 universally accepted testing regime for determining micromechanical properties of wood samples. As a result, we developed a testing system for determining compression, tension, and bending propertie...

Audrey Zink-Sharp; Carlile Price

2006-01-01

144

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

145

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

Science.gov (United States)

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

O'Brien, T. Kevin; Krueger, Ronald

2005-01-01

146

Comparison on compressive strength of paraffin waste form with H/D ratio and loading rate  

International Nuclear Information System (INIS)

In case that the mixing weight ratio of waste form between boric acid and paraffin was 3.3/1, which had been adopted in the concentrate waste drying system (CWDS) of domestic nuclear power plants. Using several specimens with different diameters and heights, 50/100mm specimens. Compressive strength were measured. The experiment result showed that the small diameter specimens of compressive strength are increased more than large diameter specimens. (d=50> 75 >100 mm) The average compressive strength of specimens showed that the range from 22.43 kgf/cm2 to 38.57 Kgf/cm2(NRC standard?4.1 Kgf/cm2). NRC standard is recommended that the compressive strength test specimens be right circular cylinders, 2 to 3 inches in diameter, with a height-to-diameter (H/D) ratio of approximately two and compressive strength were increased more than large loading rate. As test result, this conditions are a good agreement, and estimated

147

THE DENSITY, COMPRESSION STRENGTH AND SURFACE HARDNESS OF HEAT TREATED HORNBEAM (Carpinus betulus L.) WOOD  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english The heat treatment of wood is an environment-friendly method for wood preservation. The heat treatment process only uses steam and heat, and no chemicals or agents are applied to the material during the process. Tests have shown no harmful emissions are apparent when working with the material. This [...] process improves wood’s resistance to decay and its dimensional stability. In this study, the density, compression strength and hardness of heat treated hornbeam (Carpinus betulus L.) wood were investigated. Wood specimens that had been conditioned at 65% relative humidity and 20ºC were subjected to heat treatment at 170, 190, and 210 °C for 4, 8, and 12 hrs. After heat treatment, compression strength and hardness were determined according to TS 2595 and TS 2479. The results showed that the decreases of compression strength and hardness were related to the extent of density loss. Both compression strength and hardness decreased with the increasing temperatures and durations of the heat treatment. While the maximum density loss observed was 16.12% at 210 ºC and 12 hour, at these heat-treatment conditions, the compression strength approximately decreased 30% and hardness values in tangential, radial, and longitudinal directions approximately decreased by 55%, 54%, and 38%, respectively. Hence, it was concluded that there might be a relationship between changes of these wood properties.

Gokhan, Gunduz; Suleyman, Korkut; Deniz, Aydemir; Ilter, Bekar.

148

THE DENSITY, COMPRESSION STRENGTH AND SURFACE HARDNESS OF HEAT TREATED HORNBEAM (Carpinus betulus L. WOOD  

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Full Text Available The heat treatment of wood is an environment-friendly method for wood preservation. The heat treatment process only uses steam and heat, and no chemicals or agents are applied to the material during the process. Tests have shown no harmful emissions are apparent when working with the material. This process improves wood’s resistance to decay and its dimensional stability. In this study, the density, compression strength and hardness of heat treated hornbeam (Carpinus betulus L. wood were investigated. Wood specimens that had been conditioned at 65% relative humidity and 20ºC were subjected to heat treatment at 170, 190, and 210 °C for 4, 8, and 12 hrs. After heat treatment, compression strength and hardness were determined according to TS 2595 and TS 2479. The results showed that the decreases of compression strength and hardness were related to the extent of density loss. Both compression strength and hardness decreased with the increasing temperatures and durations of the heat treatment. While the maximum density loss observed was 16.12% at 210 ºC and 12 hour, at these heat-treatment conditions, the compression strength approximately decreased 30% and hardness values in tangential, radial, and longitudinal directions approximately decreased by 55%, 54%, and 38%, respectively. Hence, it was concluded that there might be a relationship between changes of these wood properties.

Gokhan Gunduz

2009-01-01

149

Relationships between microfibril angle, modulus of elasticity and compressive strength in Eucalyptus wood  

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Full Text Available Many traits are known to be important in determining the value of Eucalyptus wood as sawn timber. The commercial importance of the microfibril angle (MFA for wood quality is well established for a range of softwoods, but is less clear for hardwood species. For instance, the relationships of MFA with wood stiffness and compressive strength are unknown in Eucalyptus. Therefore, the aim of this study was to evaluate the correlation between MFA and the modulus of elasticity (Ec0,m in compression parallel to grain and compressive strength (Fc0,k using juvenile wood of Eucalyptus grandis from fast-growing plantations. The correlation between wood stiffness and compressive strength was high (0.91. The cellulose microfibril angle presented a correlation of -0.67 with wood stiffness and of -0.52 with compressive strength in Eucalyptus juvenile wood. MFA was found to be important in determining the mechanical behaviour of wood and appears to be a useful parameter to indicate wood stiffness and strength in juvenile Eucalyptus from short-rotation plantations.

Paulo Ricardo Gherardi Hein

2012-11-01

150

Relationships between microfibril angle, modulus of elasticity and compressive strength in Eucalyptus wood  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Many traits are known to be important in determining the value of Eucalyptus wood as sawn timber. The commercial importance of the microfibril angle (MFA) for wood quality is well established for a range of softwoods, but is less clear for hardwood species. For instance, the relationships of MFA wit [...] h wood stiffness and compressive strength are unknown in Eucalyptus. Therefore, the aim of this study was to evaluate the correlation between MFA and the modulus of elasticity (Ec0,m) in compression parallel to grain and compressive strength (Fc0,k) using juvenile wood of Eucalyptus grandis from fast-growing plantations. The correlation between wood stiffness and compressive strength was high (0.91). The cellulose microfibril angle presented a correlation of -0.67 with wood stiffness and of -0.52 with compressive strength in Eucalyptus juvenile wood. MFA was found to be important in determining the mechanical behaviour of wood and appears to be a useful parameter to indicate wood stiffness and strength in juvenile Eucalyptus from short-rotation plantations.

Paulo Ricardo, Gherardi Hein; José, Tarcísio Lima.

2012-11-01

151

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

152

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, 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

153

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)

154

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)

155

Compressive Strength and Setting Time of MTA and Portland Cement Associated with Different Radiopacifying Agents.  

Science.gov (United States)

Objective. The aim of this study was to evaluate the compressive strength and setting time of MTA and Portland cement (PC) associated with bismuth oxide (BO), zirconium oxide (ZO), calcium tungstate (CT), and strontium carbonate (SC). Methods. For the compressive strength test, specimens were evaluated in an EMIC DL 2000 apparatus at 0.5?mm/min speed. For evaluation of setting time, each material was analyzed using Gilmore-type needles. The statistical analysis was performed with ANOVA and the Tukey tests, at 5% significance. Results. After 24 hours, the highest values were found for PC and PC + ZO. At 21 days, PC + BO showed the lowest compressive strength among all the groups. The initial setting time was greater for PC. The final setting time was greater for PC and PC + CT, and MTA had the lowest among the evaluated materials (P tested may potentially be used in association with PC to replace BO. PMID:22957262

Tanomaru-Filho, Mario; Morales, Vanessa; da Silva, Guilherme F; Bosso, Roberta; Reis, José M S N; Duarte, Marco A H; Guerreiro-Tanomaru, Juliane M

2012-01-01

156

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

157

Effect of spherical-agglomerate strength on the distribution of force during uniaxial compression  

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We employ the carbon paper technique with the aim of investigating the effect of spherical-agglomerate (pellet) strength on force distributions, through confined compression of approximately 1 mm sized pellets formed from microcrystalline cellulose and polyethylene glycol. The carbon paper technique relies on the transference of imprints from compressed pellets onto white photo quality paper, which are digitised and processed via image processing software. The investigated pellets can both de...

Mahmoodi, Foad; Alderborn, Go?ran; Frenning, Go?ran

2011-01-01

158

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

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Full Text Available 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 cubes are used and the same sample sizes are used for testing the splitting strength. Also three different sizes of specimen are used for modulus of rupture. Preparation, casting and testing procedures are carried out according to ASTM specifications using constant mix proportion of cement/sand and water cement ratio. The obtained results show that the three mechanical properties of mortar affected by the specimen size specially the compressive strength and splitting strength of cylinders. Some best fit relationships that relate these properties are presented in this study although it cannot be generalized due to the fact that the presented results are based on limited number of tested specimens with constant mix proportion.

Sura A. Majeed

2011-01-01

159

Risk of vertebral insufficiency fractures in relation to compressive strength predicted by quantitative computed tomography  

International Nuclear Information System (INIS)

Vertebral insufficiency fractures may result from excessive loading of normal and routine loading of osteoporotic spines. Fractures occur when the mechanical load exceeds the vertebral compressive strength, i.e., the maximum load a vertebra can tolerate. Vertebral compressive strength is determined by trabecular bone density and the size of end-plate area. Both parameters can be measured non-invasively by quanti-tative computed tomography (QCT). In 75 patients compressive strength (i.e., trabecular bone density and endplate area) of the vertebra L3 was determined using QCT. In addition, conventional radiographs of the spines were analysed for the prevalence of insufficiency fractures in each case. By relating fracture prevalence to strength, 3 fracture risk groups were found: a high-risk group with strength values of L35 kN and a fracture risk near 0 percent. Biomechanical measurements and model calculations indicate that spinal loads of 3 to 4 kN at L3/4 will be common in everyday activities. These data and the results described above suggest that spines with strength values of L3<3 kN are at an extremely high risk of insufficiency fractures in daily life. Advantages of fracture risk assessment by strength determination over risk estimation based on clinically used trabecular bone density measurements are discussed. (author). 18 refs.; 4 figs

160

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

 
 
 
 
161

Incorporation of adhesive liners in amalgam: effect on compressive strength and creep.  

Science.gov (United States)

This study evaluated the effects of two adhesive resin liners (Panavia EX and Amalgambond) on the compressive strength and creep rate of a single composition high-copper amalgam alloy (Tytin). Cylindrical specimens were prepared by dead-loading or hand-condensing amalgam in a Teflon mold which was unlined, lined with Panavia EX, or lined with Amalgambond. Compressive strength specimens were tested at 1 hour, 24 hours, and 7 days after preparation. Creep specimens were tested at 7 days. The adhesive resin liners did not significantly affect the strength of the Tytin specimens prepared by dead-loading (P greater than 0.05). The Panavia EX significantly reduced the strength of the Tytin specimens prepared by hand-condensing (P less than 0.05). The creep rate was not significantly affected by either resin liner. PMID:1930843

Charlton, D G; Murchison, D F; Moore, B K

1991-08-01

162

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

163

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

164

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Akaninyene Afangide Umoh; Olusola, Kolapo O.

2012-01-01

165

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

166

Non-Uniform Compressive Strength of Debonded Sandwich Panels : I. Experimental Investigation  

DEFF Research Database (Denmark)

Face/core debond-damaged sandwich panels exposed to non-uniform compression loads are studied. The panel geometry is rectangular with a centrally located circular debond. The study primarily includes experimental methods, but simple finite element calculations are also applied. The complexity of applying a controlled non-uniform compressive load to the test panels requires a strong focus on the development of a suitable testrig. This is done by the extensive use of product development methods. The experimental results based on full-scale testing of 10 GFRP/foam core panels with prefabricated debonds show a considerable strength reduction with increasing debond diameter, with failure mechanisms varying between fast debond propagation and wrinkling-introduced face compression failure for large and small debonds, respectively. Residual strength predictions are based on intact panel testing, and a comparison between a simple numerical model and the experimental results shows fair agreement.

NØkkentved, Alexandros; Lundsgaard-Larsen, Christian

2005-01-01

167

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

Science.gov (United States)

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

Hiel, Clement; Brinson, H. F.

1993-01-01

168

Optimum Compressive Strength of Hardened Sandcrete Building Blocks with Steel Chips  

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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

169

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

170

Effect of additives on the compressive strength and setting time of a Portland cement  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Improvements in strength and setting time of Portland cements (PC) are needed to enhance their performance as endodontic and load bearing materials. This study sought to enhance the compressive strength and setting time of a PC by adding one of the following additives: 20% and 30% poly-methylmethacr [...] ylate (PMMA), 20% and 30% irregular and spherical amalgam alloys, and 10% CaCl2. The control consisted of unreinforced PC specimens. Setting time was determined using a Gillmore apparatus according to standardized methods while compressive strength was measured using a universal testing machine after 21 hours or 60 days of water storage. Data were analyzed by ANOVA, Tukey and Games-Howell tests (? = 5%). All additives significantly decreased both initial and final setting times as compared with the PC-control (p

Desirée Freitas Mryczka, Machado; Luiz Eduardo, Bertassoni; Evelise Machado de, Souza; Janaina Bertoncelo de, Almeida; Rodrigo Nunes, Rached.

2010-06-01

171

Effect of additives on the compressive strength and setting time of a Portland cement  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Improvements in strength and setting time of Portland cements (PC) are needed to enhance their performance as endodontic and load bearing materials. This study sought to enhance the compressive strength and setting time of a PC by adding one of the following additives: 20% and 30% poly-methylmethacr [...] ylate (PMMA), 20% and 30% irregular and spherical amalgam alloys, and 10% CaCl2. The control consisted of unreinforced PC specimens. Setting time was determined using a Gillmore apparatus according to standardized methods while compressive strength was measured using a universal testing machine after 21 hours or 60 days of water storage. Data were analyzed by ANOVA, Tukey and Games-Howell tests (? = 5%). All additives significantly decreased both initial and final setting times as compared with the PC-control (p

Desirée Freitas Mryczka, Machado; Luiz Eduardo, Bertassoni; Evelise Machado de, Souza; Janaina Bertoncelo de, Almeida; Rodrigo Nunes, Rached.

172

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

173

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

174

The effects of specimen scale on the compression strength of composite materials  

Science.gov (United States)

This paper presents a number of observations on the effect of specimen scale on the compression response of composite materials. Work on this topic was motivated by observations that thick-walled, unstiffened carbon reinforced cylinders subjected to hydrostatic pressure were not reaching inplane laminate stress levels at failure expected from coupon level properties, while similar cylinders reinforced with fiberglass were. Results from a study on coupon strength of (0/0/90) laminates, reinforced with AS4 carbon fiber and S2 glass fiber, are presented and show that compression strength is not a function of material or specimen thickness for materials that have the same laminate quality (autoclave cured quality). Actual laminate compression strength was observed to decrease with increasing thickness, but this is attributed to fixture restraint effects on coupon response. The hypothesis drawn from the coupon level results is further supported by results from a compression test on a thick carbon reinforced coupon in a fixture with reduced influence on specimen response and from a hydrostatic test on an unstiffened carbon reinforced cylinder subjected to hydrostatic pressure with end closures designed to minimize their effect on cylinder response.

Camponeschi, Eugene Thomas, Jr.

1994-01-01

175

Compression strength of canine bone allografts treated with various sterilization and storage methods  

International Nuclear Information System (INIS)

The objective of this study is to determine the effect of various sterilization and preservation techniques (autoclave, deep-freeze, freeze-dried, and hydrogen peroxide vapor) done at the Philippine General Hospital Tissue Bank on the compression strength of canine bone allografts. Ninety six bone segments taken from left and right matched pairs of the humerus, radius, femur and tibia were harvested from four dogs. All of the left-sided long bones were placed in the control group and all the right sided long bones were placed in the experimental group. The average weight was 2.29 gm and 2.20 gm for the control and treatment groups, respectively. The average length was 1.8 cm for the control group and 1.8 cm for the treatment group. The average compressive area was 0.55 cm sup 2 and 0.6 cm sup 2 for the control and treatment groups, respectively. In general, all bone blocks treated with autoclave and deep-freeze showed a decrease in compression strength as compared to the control group by an average of 19.88% and 18.37%, respectively Ali bone segments treated with freeze-drying and hydrogen peroxide vapor showed an increase in the compression strength as compared to the control group by an average of 23.48% and 24.63%, respectively

176

Compressive strength and microstructure of carbon nanotubes-fly ash cement composites  

International Nuclear Information System (INIS)

In this work, carbon nanotubes of 0.5 and 1% by weight were added for the first time in a fly ash cement system to produce carbon nanotubes-fly ash composites in the form of pastes and mortars. Compressive strengths of the composites were then investigated. It was found that the use of carbon nanotubes resulted in higher strength of fly ash mortars. The highest strength obtained for 20% fly ash cement mortars was found at 1% carbon nanotubes where the compressive strength at 28 days was 51.8 MPa. This benefit can clearly be seen in fly ash cement with fly ash of 20% where the importance of the addition of carbon nanotubes means that the relative strength to that of Portland cement became almost 100% at 28 days. In addition, scanning electron micrographs also showed that good interaction between carbon nanotubes and the fly ash cement matrix is seen with carbon nanotubes acting as a filler resulting in a denser microstructure and higher strength when compared to the reference fly ash mix without CNTs.

177

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)

178

The effect of impact damage and circular holes on the compressive strength of a graphite-epoxy laminate  

Science.gov (United States)

Specimens were impacted by 1.27-cm-diameter aluminum spheres with speeds ranging from 52 to 101 m/s. Some specimens were impacted without any applied compressive load and then loaded to failure to determine their residual strength. Other specimens were loaded to a prescribed axial compressive strain and impacted while at that applied load. Loaded specimens that did not fail catastrophically on impact were subsequently loaded to failure to determine their residual strength. Low-velocity impact damage was found to degrade seriously the laminate static compressive strength. Low-strain compression-compression cyclic loading was found to degrade further the compressive strength of impact-damaged specimens. Specimens with circular holes having diameters up to a third of the specimen width were loaded to failure in compression. It was found that circular holes can also degrade the static compressive strength of the laminate. The effects of circular holes and impact damage on the compressive strength of the laminate are compared.

Starnes, J. H., Jr.; Rhodes, M. D.; Williams, J. G.

1978-01-01

179

Dual-energy CT assessments of the compressive strength of vertebral cancellous bone  

International Nuclear Information System (INIS)

An in vitro study tested the correlation of QCT bone assessments with the compressive strength of fresh vertebral cancellous bone. Exactly defined cylinders of cancellous bone were studied to eliminate discrepancies between CT and physically analyzed regions. The cylinders were placed in an alignment rig, and DE-QCT scanning was performed on a Siemens DR-3. The cylinders then underwent uniaxial compression testing. Polynominal regression analyses determined the relationship between the various QCT and mechanical parameters. The mechanical parameters were significantly correlated to both the single- and dual-energy parameters. However, the fuel-energy results correlated the best

180

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

 
 
 
 
181

Strength and Permeability of Stabilized Peat Soil  

Directory of Open Access Journals (Sweden)

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

182

Correlation between the uniaxial compressive strength and the point load strength index of the Pungchon limestone, Korea  

Science.gov (United States)

Recently, the use of underground openings for various purposes is expanding, particularly for the crushing and processing facilities in open-pit limestone mines. The suitability of current rockmass classification systems for limestone or dolostone is therefore one of the major concerns for field engineers. Consequently, development of the limestone mine site characterization model(LSCM) is underway through the joint efforts of some research institutes and universities in Korea. An experimental program was undertaken to investigate the correlation between rock properties, for quick adaptation of the rockmass classification system in the field. The uniaxial compressive strength(UCS) of rock material is a key property for rockmass characterization purposes and, is reasonably included in the rock mass rating(RMR). As core samples for the uniaxial compression test are not always easily obtained, indirect tests such as the point load test can be a useful alternative, and various equations between the UCS and the point load strength index(Is50) have been reported in the literature. It is generally proposed that the relationship between the Is50 and the UCS value depends on the rock types and, also on the testing conditions. This study investigates the correlation between the UCS and the Is50 of the Pungchon limestone, with a total of 48 core samples obtained from a underground limestone mine. Both uniaxial compression and point load specimens were prepared from the same segment of NX-sized rock cores. The derived equation obtained from regression analysis of two variables is UCS=26Is50, with the root-mean-square error of 13.18.

Baek, Hwanjo; Kim, Dae-Hoon; Kim, Kyoungman; Choi, Young-Sup; Kang, Sang-Soo; Kang, Jung-Seock

2013-04-01

183

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

184

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

Directory of Open Access Journals (Sweden)

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

185

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

Directory of Open Access Journals (Sweden)

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

Vijaykumar H.K

2014-07-01

186

A mechanism responsible for reducing compression strength of through-the-thickness reinforced composite material  

Science.gov (United States)

A study was conducted to identify one of the mechanisms that contributes to the reduced compression strength of composite materials with through-the-thickness (TTT) reinforcements. In this study a series of thick (0/90) laminates with stitched and integrally woven TTT reinforcements were fabricated and statically tested. In both the stitching and weaving process a surface loop of TTT reinforcement yarn is created between successive TTT penetrations. It was shown that the surface loop of the TTT reinforcement 'kinked' the in-plane fibers in such a manner that they were made ineffective in carrying compressive load. The improvement in strength by removal of the surface loop and 'kinked' in-plane fibers was between 7 and 35 percent.

Farley, Gary L.

187

Tensile strength and internal stress determination in salt compacts by diametrical and axial compression tests  

International Nuclear Information System (INIS)

Due to the brittle character of the material an indirect method (diametrical and axial compression testing) was adopted for tensile strength determination. Two lots of compacts were prepared from salt powder, by pressing it in steel dyes by means of a hydraulic press. For uniaxial tests, cylindrical compacts were used. Biaxial tests were done on disk-shaped compacts, each disk having a diametrical V-shaped cut on one of its plane areas. The punches used for compression tests, were designed to obtain a ratio of 1.2 between their curvature radius and sample radius. At the same time with the tensile strength, the stress intensity factor (KIC and KIIC values) has been obtained. The results obtained are in good agreement with the mechanical properties of the salt, previously reported. (Authors)

188

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

189

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

190

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

191

Characterizing compressive and fracture strengths of fiber reinforced composites using off-axis specimens  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present report focuses on testing and modeling strain rate dependent compressive and fracture strengths of unidirectional fiber reinforced composites by using off-axis specimens. Experimental results in split Hopkinson pressure bar (SHPB) tests with AS4/3501-6 off-axis specimens showed large bending wave existing in the incident bar and transmission bar because of the strong interface friction induced by the direct contacts between the stiff fiber ends and loading surfaces, thus the exten...

Bing, Qida

2006-01-01

192

Uniaxial compressive strength prediction of jet grouting columns using support vector machines  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Uniaxial compressive strength (UCS) is the mechanical properties currently used in geotechnical works design, namely in jet grouting (JG) treatments. However, when working with this soil improvement technology, due to its inherent geological complexity and high number of variables involved, such design is a hard, perhaps very hard task. To help in such task, a support vector machine (SVM), which is a data mining algorithm particularly adequate to explore high number of complex data, was train...

Tinoco, Joaquim; Correia, A. Gomes; Cortez, Paulo

2011-01-01

193

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 st...

Audinarayana, D.

2013-01-01

194

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

195

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

196

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

Directory of Open Access Journals (Sweden)

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

197

Effect of Pore Fluid Salinity on Compressibility and Shear Strength Development of Clayey Soils  

Science.gov (United States)

Investigations of shear strength, compressibility and moisture content of a recent marine clay in the Caspian Sea showed soil profiles with a lower shear strength and higher moisture content, than expected for a normally consolidated soil. Further, measured preconsolidation pressures were lower than the calculated in-situ effective stress, suggesting that the deposit was underconsolidated. The pore fluid salinity was also measured and showed an increase with depth up to saturation concentration. A research project was carried out to study the effect of pore fluid salinity on shear strength and compressibility of remoulded clays. Results of this study showed that increasing pore fluid salinity caused a decrease of the moisture content for a normally consolidated clayey soil of high plasticity. The remoulded shear strength corresponded with the measured moisture contents. The observed compressive behaviour of these clays is explained using the modified effective stress concept, which considers not only (excess) pore pressure and effective pressure, but also the electrochemical repulsive and attractive forces between the clay particles. The laboratory tests on remoulded clays show opposite results to the measurements on the natural soils. The effects of soil structure are used to explain the differences for the measurements of moisture content, undrained shear strength and preconsolidation pressure. The oedometer test procedure was reviewed and additional tests were performed on natural clay samples from this site. Results showed that the measured pre-consolidation pressure depends largely on the salinity of the permeating fluid used in the oedometer apparatus and suggest that when testing marine clays with very high pore fluid salinity, using a brine solution that closely resembles the pore fluid chemistry yields a measured preconsolidation pressure closer to the known geological stress history.

van Paassen, Leon A.; Gareau, Laurent F.

198

Effect of initial properties on the flow strength of aluminum during quasi-isentropic compression  

Science.gov (United States)

A magnetic loading technique was used to ramp load pure aluminum and 6061 aluminum alloy to peak stresses of approximately 29GPa. The peak loading rate was approximately 106/s, followed by unloading from peak stress at a rate of about 105/s. The pure aluminum samples had impurity levels ranging from about 10ppmto0.5wt% and average grain sizes in the range of 144-454?m. The 6061 alloy was prepared in either the T6 condition with grain sizes of 5-50?m, or in the T0 or T6 heat treatment condition with a grain size of about 40?m. A wave profile technique was used to estimate the compressive strength during unloading. It was found that the compressive strength estimated during unloading increased with peak stress for all materials and that the change in strength was insensitive to initial material properties. This observation is in agreement with previous results obtained from shock loading of the same materials [H. Huang and J. R. Asay, J. Appl. Phys. 98, 033524 (2005)] and suggests that the deformation mechanisms, which govern strength properties at high strain rates, are similar for the two cases. It was also found that the quasielastic strain occurring during unloading saturated at about 2% in 6061-T6 alloy for peak stresses in the range of 10-50GPa. The change in quasielastic strain was found to be similar for pure aluminum and 6061 alloys.

Asay, J. R.; Ao, T.; Davis, J.-P.; Hall, C.; Vogler, T. J.; Gray, G. T.

2008-04-01

199

Compressive strength of radiation-induced polymer impregnated hardened cement pastes  

International Nuclear Information System (INIS)

Hardened cement paste (HPC) specimens with 0.22, 0.30, 0.40 and 0.50 W/C ratios were prepared by curing under water for 1, 3, 7 and 28 days. Impregnation was carried out under vacuum with methyl methacrylate, styrene and 60:40 wt% styrene-acrylonitrile mixture. Polymerization has been induced by ?-ray irradiation of wrapped specimens with different absorbed dose levels depending on the type of monomer used for impregnation. Considerable improvement in compressive strength has been achieved for impregnated HCP specimens over unirradiated controls. The extent of strength improvement is larger for early curing ages than for later ones. Also, impregnation with the styrene-acrylonitrile copolymer gave the best strength results, followed by polymethyl methacrylate and then polystyrene. The results are discussed in terms of the structure of HCP, the nature of the monomer and the radiation dose. (author)

200

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

 
 
 
 
201

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

202

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

203

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

204

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.

2014-08-01

205

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

206

Characterizing compressive and fracture strengths of fiber reinforced composites using off-axis specimens  

Science.gov (United States)

The present report focuses on testing and modeling strain rate dependent compressive and fracture strengths of unidirectional fiber reinforced composites by using off-axis specimens. Experimental results in split Hopkinson pressure bar (SHPB) tests with AS4/3501-6 off-axis specimens showed large bending wave existing in the incident bar and transmission bar because of the strong interface friction induced by the direct contacts between the stiff fiber ends and loading surfaces, thus the extension-shear coupling was prevented fully developing in the off-axis specimens under compression and the one-dimensional wave propagation assumption in the SHPB analysis was violated. Through the vapor deposition technique a thin titanium layer is coated on both specimen ends, smooth sliding between loading surfaces and specimen ends assures the pressure is the only interaction. Stress-strain curves are generated at different strain rate using this type of specimens with various off-axis angles under strain controlled testing mode. From these curves a rate-dependent viscoplasticity constitutive model is developed to predict the stress-strain relations at various strain rates and a compressive strength model is established from the viscoplasticity model for AS4/3501-6 carbon/epoxy composite. Comparison between the model predictions and experimental results shows good agreement and indicates that the compressive strength model obtained by using low strain rate test data is valid for high strain rate too. From the established rate dependent compressive strength model, the longitudinal compressive strengths at various strain rates are predicted. Through an extrapolation technique proposed in the work, rate dependent 0° compressive strengths of unidirectional AS4/3501-6 composite are obtained from off-axis test data and compared to model predictions. By utilizing the advantage of off-axis specimens that a combined stress state can be obtained from a simple uniaxial loading, a new method to perform mode II fracture tests is presented which involves using off-axis specimen by properly introducing a pre-crack in the specimen along the fiber direction. Static off-axis fracture tests are conducted with S2/8552 glass/epoxy composite at various off-axis angles and finite element (FE) method is used to evaluate the critical mode II energy release rate (fracture toughness). Note that the crack surface is not frictionless and existence of pressure on the crack surfaces, crack surface friction is considered in the FE analysis and it is found that the virtual crack closure method is still valid in the presence of crack surface friction. Different crack surface frictions are obtained by varying the off-axis angle and friction effect on mode II fracture toughness of S2/8552 glass/epoxy composite is found to increase as off-axis angle increases. Moreover, the transverse compressive stress is found to have significant effect on mode II energy release rate from FE analysis. The small size of block off-axis specimen makes it possible to perform dynamic fracture tests on a SHPB setup and high crack propagation speed is obtained with this type of specimen. By defining a time rate of mode II energy release rate GcI? to represent the load rate or using average strain rate of the off-axis specimen, it is found that the dynamic initiation mode II fracture toughness is larger than the static value of mode II fracture toughness and a load rate effect is observed. Specimen size effects in off-axis compression tests are studied as well by conducting experiments with small block off-axis specimens of low modulus S2 glass fiber reinforced composites and high modulus AS4 carbon fiber reinforced composites. It was found that the off-axis compressive strength of the glass/epoxy composite decreased by a small amount (<5%) when increasing either specimen width or thickness. However, an appreciable reduction in off-axis compressive strength of the high modulus carbon/epoxy composite was observed as specimen width or thickness increased with lapped specimens. But when a

Bing, Qida

207

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

208

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.

209

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

210

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.

211

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

Directory of Open Access Journals (Sweden)

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

Juliette Fitremann

2010-09-01

212

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.

Delarche, Antoine Technical University of Denmark,

2009-01-01

213

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

Science.gov (United States)

The present paper reports on the results of some experiments obtained from the production, hydration and subsequent measurement of the mechanical properties of several mortars prepared using a commercial CII/B-LL Portland cement, steelmaking slag, superplasticizer and water. Relevant parameters for the mortar preparation are the weight ratios of cement/water, the weight ratio superplasticizer/cement and between fine and granulated coarse particles. It has been demonstrated that optimisation of such parameters leads to the production of materials with mechanical properties suitable for civil engineering applications. Moreover, materials with improved compressive strength can be prepared by the use of slag containing extensive amounts of large particles. PMID:19740511

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

2009-11-01

214

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

215

Shear strength of irradiated insulation under combined shear/compression loading  

International Nuclear Information System (INIS)

The shear strengths of irradiated insulation systems were measured at 4 K under combined shear and compression loads. Sandwich-type (316LN/bonded insulation/316LN) specimens were irradiated at 4 K and tested at 4 K after storage at room temperature. Some specimens were stored at room temperature; others, at 77 K. Insulation systems included diglycidylether of bisphenol-A and tetraglycidyl diaminodiphenyl methane epoxies and polyimide resins reinforced with S-2 glass. Some contained polyimide film or mica electrical barriers. All specimens were irradiated to a fast neutron fluence of 1.8 X 1022 n/m2. Insulation systems are compared on the basis of their irradiated and unirradiated shear strengths

216

Method for increasing the rate of compressive strength gain in hardenable mixtures 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 provides a method for increasing the rate of strength gain of a hardenable mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the hardenable mixture. The invention further relates to such hardenable mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a hardenable mixture. The hardenable mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points.

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

1997-01-01

217

Noninvasive prediction of vertebral body compressive strength using nonlinear finite element method and an image based technique.  

Science.gov (United States)

Noninvasive prediction of vertebral body strength under compressive loading condition is a valuable tool for the assessment of clinical fractures. This paper presents an effective specimen-specific approach for noninvasive prediction of human vertebral strength using a nonlinear finite element (FE) model and an image based parameter based on the quantitative computed tomography (QCT). Nine thoracolumbar vertebrae excised from three cadavers with an average age of 42 years old were used as the samples. The samples were scanned using the QCT. Then, a segmentation technique was performed on each QCT sectional image. The segmented images were then converted into three-dimensional FE models for linear and nonlinear analyses. A new material model was implemented in our nonlinear model being more compatible with real mechanical behavior of trabecular bone. A new image based MOS (Mechanic of Solids) parameter named minimum sectional strength ((sigma(u)A)(min)) was used for the ultimate compressive strength prediction. Subsequently, the samples were destructively tested under uniaxial compression and their experimental ultimate compressive strengths were obtained. Results indicated that our new implemented FE model can predict ultimate compressive strength of human vertebra with a correlation coefficient (R(2)=0.94) better than usual linear and nonlinear FE models (R(2)=0.83 and 0.85 respectively). The image based parameter introduced in this study ((sigma(u)A)(min)) was also correlated well with the experimental results (R(2)=0.86). Although nonlinear FE method with new implemented material model predicts compressive strength better than the (sigma(u)A)(min), this parameter is clinically more feasible due to its simplicity and lower computational costs. This can make future applications of the (sigma(u)A)(min) more justified for human vertebral body compressive strength prediction. PMID:19781969

Zeinali, Ahad; Hashemi, Bijan; Akhlaghpoor, Shahram

2010-04-01

218

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

219

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

220

Effect of isothermal annealing on the compressive strength of a ZrAlNiCuNb metallic glass  

International Nuclear Information System (INIS)

Research highlights: ? Only structural relaxation happens during annealing at the temperature below Tg. ? Nanocrystallization happens during annealing at the temperature above Tg. ? The compressive strength increases with annealing time up to 20 min. ? The compressive strength decreases with annealing time after 20 min. - Abstract: The effects of isothermal annealing on the microstructures and compressive strength of a Zr56Al10.9Ni4.6Cu27.8Nb0.7 bulk metallic glass (BMG) have been studied using X-ray diffraction, scanning electron microscopy and compression tests. It has been shown that only structural relaxation happens during annealing at the temperature below Tg (glass transition temperature), while both structural relaxation and nanocrystallization happen during annealing at the temperature above Tg. Compression tests indicated that the strength of the BMG increases with annealing time at 437 deg. C up to 20 min, after which the strength starts to decrease. The strength evolution of the BMG with the annealing time is due to combined effects of the variations of the free volume and nanocrystals.

 
 
 
 
221

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

222

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

223

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.

224

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

225

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.

2014-08-01

226

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

227

Fixation of waste materials in grouts. Part II. An empirical equation for estimating compressive strength for grouts from different wastes  

International Nuclear Information System (INIS)

Compressive strength data for grouts prepared from three different nuclear waste materials have been correlated. The wastes include ORNL low-level waste (LLW) solution, Hanford Facility Waste (HFW) solution, and Hanford cladding removal waste (CRW) slurry. Data for the three wastes can be represented with a 0.96 coefficient of correlation by the following equation: S = -9.56 + 9.27 D/I + 18.11/C + 0.010 R, where S denotess 28-d compressive strength, in mPa; D designates Waste concentration, fraction of the original; I is ionic strength; C denotes Attapulgite-150 clay content of dry blend, in wt %; and R is the mix ratio, kg/m3. The equation may be used to estimate 28-d compressive strengths of grouts prepared within the compositional range of this investigation

228

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

229

Effect of high volume of fly ash from 5 sources on compressive strength and acid resistance of concrete  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this research was to examine the effect of high volume of fly ash from various sources on compressive strength and acid resistance of concrete. Fly ashes from 5 sources were collected and classified by an air classifier into 3 groups of different degree of fineness; low, medium, and high fineness. Portland cement type I was replaced by fly ash at the rate of 50% by weight of cementitious materials (Portland cement type I and fly ash to cast concrete cylinders of 10 cm in diameter and 20 cm in height. After fly ash concreteswere cured in water for 28 days, they were tested to determine the compressive strength. In addition, the specimens were immersed in 3% of sulfuric acid solution and the weight losses of concretes were measured from 3 to 90 days. It was found that the compressive strengths of fly ash concretes were more than 77% of the control concrete when the high fineness fly ashes were used. Each source of the fly ash had different effect on the compressive strength as well as on the sulfuric acid resistance of concrete. The compressive strength of fly ash concrete was improved with the use of high fineness fly ash; however, the sulfuric acid resistance of the concrete tended to decrease as the fineness of fly ash increased.

Vivatanachang, N.

2004-03-01

230

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

231

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

International Nuclear Information System (INIS)

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.

232

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.

233

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

234

Compressive strength of titanium alloy skin-stringer panels selectively reinforced with boron-aluminum composite.  

Science.gov (United States)

Description of a method of selectively reinforcing conventional titanium airframe structure with unidirectional boron-aluminum composite attached by brazing which has been successfully demonstrated based on compression tests of short skin-stringer panels. Improvements in structural performance exceeded 25% on an equivalent weight basis over the range from room temperature to 800 F, both in terms of initial buckling and maximum strengths. Room-temperature performance was not affected by prior exposure at 600 F for 1000 hours in air, or by 400 cycles between -65 and 600 F. The experimental results were generally predictable on the basis of existing analytical procedures. No evidence of failure was observed in the braze bond between the boron-aluminum composite and the titanium alloy.

Herring, H. W.; Carri, R. L.

1972-01-01

235

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 materials and components all sourced locally. The performance of the fabricated machine was finally evaluated against a standard foreign machine in the Standards Organisation of Nigeria using statistical methods and the result showed that the locally fabricated machine is 97% effective.

Abdulkadir Baba HASSAN

2009-07-01

236

Enhancing Ultimate Compressive Strength of Notch Embedded Steel Cylinders Using Overwrap CFRP Patch  

Science.gov (United States)

In this study, the application of Fiber Reinforced Polymer (FRP) patch for strengthening of the damaged area in thin walled steel cylinders under compression loading was investigated. In this direction, some experimental tests were carried out on the selected notch induced specimens with unique diameter-to-thickness ratio (D/t). The obtained results were compared to the intact cylinder in order to find out the reduction effect of notch on the buckling load of cylinders. Following that, the notched specimens were treated using externally FRP by wrapping around the notched area and the stability strength of the retrofitted specimens was measured experimentally. The investigation was also carried out in numerical analysis using FEM in order to develop the proposed technique for determination of optimum FRP configurations and also better understanding of the experimental observations considering the nonlinear behavior and failure modes for composite member.

Kabir, Mohammad Z.; Nazari, Alireza

2012-06-01

237

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

238

Effect of synthesis parameters on the compressive strength of low-calcium ferronickel slag inorganic polymers.  

Science.gov (United States)

The wide range of physical and chemical properties of inorganic polymers, also known as geopolymers, commonly formed by alkali activation of aluminosilicates, makes these materials useful for a variety of applications. In the present experimental study inorganic polymers are synthesised from low-Ca electric arc ferronickel slag. The effect of experimental conditions on the compressive strength of the final products is assessed. A number of techniques, namely XRD, FTIR and TG-DTG were used to identify new phases and subsequently elucidate to some degree the mechanisms involved. Finally, the paper discusses briefly the potential of inorganic polymer technology as a feasible option for the utilisation of certain potentially hazardous mining and metallurgical wastes towards an increased sustainability of the wider minerals sector. PMID:18508195

Komnitsas, Kostas; Zaharaki, Dimitra; Perdikatsis, Vasillios

2009-01-30

239

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.

Pedersen, Preben Terndrup

1996-01-01

240

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

 
 
 
 
241

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

242

Experiments on the enhancement of compressible mixing via streamwise vorticity. II - Vortex strength assessment and seed particle dynamics  

Science.gov (United States)

The effect of streamwise vorticity on compressible axisymmetric mixing layers is examined using vortex strength assessment and seed particle dynamics analysis. Experimental results indicate that the particles faithfully represent the dynamics of the turbulent swirling flow. A comparison of the previously determined mixing layer growth rates with the present vortex strength data reveals that the increase of turbulent mixing up to 60 percent scales with the degree of swirl. The mixing enhancement appears to be independent of the compressibility level of the mixing layer.

Naughton, J. W.; Cattafesta, L. N.; Settles, G. S.

1993-01-01

243

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

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

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

Directory of Open Access Journals (Sweden)

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

246

Predicting the compressive and tensile strength of rocks from indentation hardness index  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english The prediction of rock properties from indirect testing methods is important, particularly for preliminary investigations since indirect tests are easier and cheaper than the direct tests. In this study, we investigate the predictability of the uniaxial compressive strength (UCS) and Brazilian tensi [...] le strength (BTS) of rocks from the indentation hardness index (IHI) obtained using point load apparatus. Forty-six different rock types, 14 of which were igneous, 15 were metamorphic, and 17 were sedimentary were tested in the laboratory. The UCS and BTS values were correlated with the corresponding IHIvalues and the results were statistically analysed. The influence of rock classes on the relationships was also investigated. A strong correlation between UCS and IHI was found for all data. The correlation between BTS and IHI is not as strong as the correlation between UCS and IHI. However, it is in the acceptable limits. When the regression analyses were repeated for igneous, metamorphic, and sedimentary rocks, the correlation coefficients were generally increased. The results show the UCS and BTS can be estimated from IHI. In addition, the effect of rock classes on the relationships between IHI and both UCS and BTS is important.

S, Kahraman; M, Fener; E, Kozman.

2012-05-01

247

Predicting the compressive and tensile strength of rocks from indentation hardness index  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english The prediction of rock properties from indirect testing methods is important, particularly for preliminary investigations since indirect tests are easier and cheaper than the direct tests. In this study, we investigate the predictability of the uniaxial compressive strength (UCS) and Brazilian tensi [...] le strength (BTS) of rocks from the indentation hardness index (IHI) obtained using point load apparatus. Forty-six different rock types, 14 of which were igneous, 15 were metamorphic, and 17 were sedimentary were tested in the laboratory. The UCS and BTS values were correlated with the corresponding IHIvalues and the results were statistically analysed. The influence of rock classes on the relationships was also investigated. A strong correlation between UCS and IHI was found for all data. The correlation between BTS and IHI is not as strong as the correlation between UCS and IHI. However, it is in the acceptable limits. When the regression analyses were repeated for igneous, metamorphic, and sedimentary rocks, the correlation coefficients were generally increased. The results show the UCS and BTS can be estimated from IHI. In addition, the effect of rock classes on the relationships between IHI and both UCS and BTS is important.

S, Kahraman; M, Fener; E, Kozman.

248

An investigation of the effect of aggregate on concrete compressible strength  

Science.gov (United States)

Findings of an investigation were compiled whose objectives were to determine the significance of variation in the plastic properties of concrete as denoted by construction records; to isolate those variables that also have an affect on the hardened properties of concrete; to determine if rigid control of aggregate gradation could be justified by requiring the aggregate to be separate into several size fractions prior to field batching in order to produce a durable superior concrete; and to evaluate the microwave oven tehnique of determing the water-cement ratio of plastic concrete. The statistical analysis of ten years of concrete construction data showed that some sources of coarse aggregate had not met their expected strengths and that concretes made of type 2 cements were found to produce compressive strengths about eight percent higher than concrete made of type 1 cements. Findings from laboratory testing implied that improved durability may be obtained by requiring tight control on the coarse aggregate gradation by separating it into three size fractions. The microwave technique appears to be a viable method of determining the water cement ratio of plastic concrete.

Gress, D. L.

1982-03-01

249

Formulation of reduction rate for ultimate compressive strength of stiffened panel induced by opening  

Science.gov (United States)

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

Yu, Chang-li; Lee, Joo-sung

2014-08-01

250

Strength of Tantalum at High Pressures through Richtmyer-Meshkov Laser Compression Experiments and Simulations  

Science.gov (United States)

Strength at extreme pressures (>1 Mbar or 100 GPa) and high strain rates (106-108 s-1) of materials is not well characterized. The goal of the research outlined in this thesis is to study the strength of tantalum (Ta) at these conditions. The Omega Laser in the Laboratory for Laser Energetics in Rochester, New York is used to create such extreme conditions. Targets are designed with ripples or waves on the surface, and these samples are subjected to high pressures using Omega's high energy laser beams. In these experiments, the observational parameter is the Richtmyer-Meshkov (RM) instability in the form of ripple growth on single-mode ripples. The experimental platform used for these experiments is the "ride-along" laser compression recovery experiments, which provide a way to recover the specimens having been subjected to high pressures. Six different experiments are performed on the Omega laser using single-mode tantalum targets at different laser energies. The energy indicates the amount of laser energy that impinges the target. For each target, values for growth factor are obtained by comparing the profile of ripples before and after the experiment. With increasing energy, the growth factor increased. Engineering simulations are used to interpret and correlate the measurements of growth factor to a measure of strength. In order to validate the engineering constitutive model for tantalum, a series of simulations are performed using the code Eureka, based on the Optimal Transportation Meshfree (OTM) method. Two different configurations are studied in the simulations: RM instabilities in single and multimode ripples. Six different simulations are performed for the single ripple configuration of the RM instability experiment, with drives corresponding to laser energies used in the experiments. Each successive simulation is performed at higher drive energy, and it is observed that with increasing energy, the growth factor increases. Overall, there is favorable agreement between the data from the simulations and the experiments. The peak growth factors from the simulations and the experiments are within 10% agreement. For the multimode simulations, the goal is to assist in the design of the laser driven experiments using the Omega laser. A series of three-mode and four-mode patterns are simulated at various energies and the resulting growth of the RM instability is computed. Based on the results of the simulations, a configuration is selected for the multimode experiments. These simulations also serve as validation for the constitutive model and the material parameters for tantalum that are used in the simulations. By designing samples with initial perturbations in the form of single-mode and multimode ripples and subjecting these samples to high pressures, the Richtmyer-Meshkov instability is investigated in both laser compression experiments and simulations. By correlating the growth of these ripples to measures of strength, a better understanding of the strength of tantalum at high pressures is achieved.

John, Kristen Kathleen

251

Compressive strength of glass fiber reinforced composites at room temperature, 77 K and 4.2 K  

International Nuclear Information System (INIS)

Experiments to determine the ultimate compressive strengths of industrial high-pressure laminates are reported. The choice of materials has been restricted to low cost unidirectional glass fiber and glass cloth reinforcement in matrices of polyester, vinyl ester, and epoxy. Measurements on 1.27 cm diameter rods at room temperature, 77 k and 4.2 k have been made

252

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

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

FAREED AHMED MEMON

2013-02-01

253

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

254

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

255

Effect of Impact Damage and Open Holes on the Compression Strength of Tough Resin/high Strain Fiber Laminates  

Science.gov (United States)

Tests to assess the performance of composite structures damaged by impact or containing local discontinuities such as cutouts are discussed. In particular, two plate specimen test configurations which were developed to define the serverity of compression strength reduction are described; one for impact damage and the other open hole specimens. The test technique for impact specimens involves damaging the plate at selected energies, measuring the size of damage by ultrasonic C-scan techniques and measuring the residual strength in a compression load test. Open-hole specimen compression tests are conducted for several different hole diameters and the failure strain and load and mode of failure recorded. The plate specimen used in these tests is designed with length, width, thickness and laminate stiffness to ensure that overall plate buckling is not responsible for initiating failure.

Williams, J. G.

1984-01-01

256

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.

257

Development of a method for evaluating tensile and compressive strengths of discontinuous rock mass considering scale effect  

International Nuclear Information System (INIS)

The purpose of this research is to develop a method for evaluating tensile and compressive strengths considering scale effect which is an old problem in rock mechanics. The method is based on the results of investigation on geometrical information of discontinuity distribution in rock mass. We created a three-dimensional structural model of rock mass with reference to previous studies. Discontinuities in the 3D model were arranged in the supposed cube which is equal to the size of FEM mesh in stability analysis. We clipped arbitrarily-sized two-dimensional cross-section model from the 3D model and calculated tensile and compressive strengths of the 2D model by the stress analysis method we proposed. The relationship between the strength and the size, or the scale effect can be obtained from the method previously describe. The results of the simulations of the proposed method agree with the past test results that the strength and the rate of change of strength decreases with decreasing scale, and show that the scale effect varies according to conditions of geometrical information of discontinuity, confining stress and compression or tension. (author)

258

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)

259

The Influence of Rock Properties and Size into Strength Criteria: A Proposed Criterion for Soft Rock Masses  

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Full Text Available A new modified strength criterion for soft rock masses is proposed in this paper in order to provide a suitable estimation for soft rock mass strength. The new criterion is based upon the current compression test data of soft materials of over 150 samples, and available published data of soft rock strength. It is shown that the proposed criterion estimates reasonable values of soft rock mass strength. Rock properties and size contribute significantly into the strength, represented by friction angle and unconfined compressive strength. Examples exercised reveal that the structure of soft rock masses takes a dominant part in controlling the strength, which then determines the modelled strength of soft rock masses. The results also show that the strength of the proposed equation could relatively be higher three times than the strength of the Hoek-Brown criterion for a massive soft rock mass.

Agustawijaya D.S.

2011-01-01

260

Reliability Assessment of Buckling Strength for Compressed Cylindrical Shells with Interacting Localized Geometric Imperfections  

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Full Text Available Problem statement: Elastic cylindrical shells are common structures in the fields of civil engineering and engineering mechanics. These thin-walled constructions may undergo buckling when subjected to axial compression. Buckling limits to large extent their strength performance. This phenomenon depends hugely on the initial distributed or localized geometric imperfections that are present on the shell structure. Localized geometric imperfections result in general from the operation of welding strakes to assemble the shell structure. In this study, reliability of buckling strength as it could be affected by shell material and geometry parameters was investigated. The localized geometric imperfections were chosen to be entering and having either a triangular or a wavelet form. Interaction between three localized imperfections had also been considered. Approach: A special software package which was dedicated to buckling analysis of quasi axisymmetric shells was used in order to compute the buckling load via the linear Euler buckling procedure. A set of five factors including shell aspect ratios, defect characteristics and the distance separating the localized initial geometric imperfections had been found to govern the buckling problem. A parametric study was performed to determine their relative influence on the buckling load reduction. Reliability analysis was carried out by using first order reliability method. Results: Wavelet imperfection was found to be more severe than triangular form in the range of low amplitude imperfections. It was shown also by comparison with the single imperfection case that further diminution of the critical load is obtained for three interacting imperfections. The interval distance separating the localized geometric imperfections was found to have important influence on the reliability index. Conclusion/Recommendations: In the he range of investigated parameters, reliability was found to increase with the distance separating the localized geometric imperfections. This can help performing optimal design of assembled strakes.

Jalal E. Bahaoui

2010-01-01

 
 
 
 
261

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.

262

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

263

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

264

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

265

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

266

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

267

An engineering procedure for calculating compressive strength of isogrid cylindrical shells with buckled skin  

Science.gov (United States)

An engineering procedure is presented for calculating the compressive buckling strength of isogrid cylinders using shell of revolution techniques and accounting for loading beyond the material proportional limit and/or local buckling of the skin prior to general buckling. A general nondimensional chart is presented which can be used in conjunction with formulas based on simple deformation plasticity theory to calculate postbuckling stiffnesses of the skin. The stiffening grid system is treated as an equivalent isotropic grid layer. Stiffnesses are determined for this grid layer, when loaded beyond the proportional limit, by the same plasticity theory used for the skin and a nonlinear stress-strain curve constructed from simple isogrid-handbook formulas and standard-reference-manual stress-strain curves for the material involved. Comparison of prebuckling strains and buckling results obtained by this procedure with data from a large isogrid-cylinder test is excellent with the calculated buckling load no more than 4 percent greater than the test value.

Heard, W. L., Jr.; Anderson, M. S.; Slysh, P.

1976-01-01

268

Effect of Superplasticizer and Extra Water on Workability and Compressive Strength of Self-Compacting Geopolymer Concrete  

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Full Text Available This study documents the results of an experimental work carried out to investigate the effect of superplasticizer and amount of extra water on strength and workability properties of Fly ash-based Selfcompacting geopolymer concrete. The experiments were conducted by varying the amount of extra water and dosage of superplasticizer. A total of nine mixtures with superplasticizer content varying from 3 to 7% and extra water ranging from 10 to 20% of the mass of fly ash were prepared and tested. The essential workability properties of the freshly prepared concrete such as filling ability, passing ability and segregation resistance were evaluated by using Slump flow, T50 slump flow, V-funnel, L-box and J-ring test methods. The compressive strength tests were carried out at 1, 3, 7 and 28 days. Test results indicated that extra water and superplasticizer are key parameters and play an important role in the development of self-compacting geopolymer concrete. Workability of self-compacting geopolymer concrete was dependent on the amount of extra water and dosage of superplasticizer. With the increase in amount of extra water and superplasticizer, the workability was improved. However, the addition of water beyond 15% resulted in bleeding as well as segregation and decreased the compressive strength of the concrete. The compressive strength of self-compacting geopolymer concrete was significantly decreased as the amount of extra water exceeded 12% by mass of Fly ash.

Fareed Ahmed Memon

2012-03-01

269

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

270

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

271

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

Directory of Open Access Journals (Sweden)

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

Floriberto Díaz-Díaz

2013-11-01

272

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

273

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)

274

In situ micropillar compression reveals superior strength and ductility but an absence of damage in lamellar bone  

Science.gov (United States)

Ageing societies suffer from an increasing incidence of bone fractures. Bone strength depends on the amount of mineral measured by clinical densitometry, but also on the micromechanical properties of the hierarchical organization of bone. Here, we investigate the mechanical response under monotonic and cyclic compression of both single osteonal lamellae and macroscopic samples containing numerous osteons. Micropillar compression tests in a scanning electron microscope, microindentation and macroscopic compression tests were performed on dry ovine bone to identify the elastic modulus, yield stress, plastic deformation, damage accumulation and failure mechanisms. We found that isolated lamellae exhibit a plastic behaviour, with higher yield stress and ductility but no damage. In agreement with a proposed rheological model, these experiments illustrate a transition from a ductile mechanical behaviour of bone at the microscale to a quasi-brittle response driven by the growth of cracks along interfaces or in the vicinity of pores at the macroscale.

Schwiedrzik, Jakob; Raghavan, Rejin; Bürki, Alexander; Lenader, Victor; Wolfram, Uwe; Michler, Johann; Zysset, Philippe

2014-07-01

275

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

276

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

277

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.

2014-08-01

278

Effect of Elevated Temperature and Aggressive Chemical Environment on Compressive Strength of M-30 Grade of Concrete Composite.  

Directory of Open Access Journals (Sweden)

Full Text Available The present paper reports result of an experimental program conducted to study the behavior of M-30 grade of concrete at elevated temperature on the basis of physical appearance, weight loss and residual compressive strength test. The concrete cubes(M-30 of 150×150×150 mm were cast with a ratio of 1:1.26:2.8 by weight. Three cubeswere tested for compressive strength at the age of 7 days and 28 days by universal testing machine. Then the specimen were subjected to the elevated temperature 200o c, 400o c, 600o c, 800o c and 1000o c in an electric air heated muffle and after cooling were tested for the compressive strength. Six cubes were immersed in each solution of sodium sulphate, sulfuric acid, and sodium chloride for 30 days and 60 days. The testreveal the properties of M-30 concrete and its applicability at elevated temperature and against aggressive environment such as acid attack, sulphate attack and chloride attack. Keywords:

Chandan Kumar

2014-05-01

279

Effects of carbonation on the leachability and compressive strength of cement-solidified and geopolymer-solidified synthetic metal wastes.  

Science.gov (United States)

The effects of accelerated carbonation on the compressive strength and leachability of fly ash-based geopolymer and ordinary portland cement (OPC) doped with Cd(II), Cr(III), Cr(VI), Cu(II), Pb(II) or Zn(II) salts were investigated. Cement was effective at immobilizing Cd, Cr(III), Cu, Pb and Zn under both the Synthetic Precipitation Leaching Procedure (SPLP) and the Toxicity Characteristic Leaching Procedure (TCLP), but ineffective for retaining Cr(VI). Carbonated cement maintained its ability to immobilize Cd, Cr(III), Pb and Zn, but, under acidic TCLP conditions, was much worse at retaining Cu. Geopolymer was effective at immobilizing Cr(III) and Cu, and, to a lesser degree, Cd, Pb and Zn in SPLP leaching tests. Only Cr(III) was immobilized under comparatively acidic TCLP testing conditions. Carbonation did not change the metal retention capacity of the geopolymer matrix. Metal doping caused compressive strengths of both geopolymer and cement to decrease. Carbonation increased the compressive strength of cement, but decreased that of the geopolymer. Geochemical equilibrium modeling provided insight on the mechanisms of metal immobilization. PMID:22406845

Pandey, Bhishan; Kinrade, Stephen D; Catalan, Lionel J J

2012-06-30

280

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)

 
 
 
 
281

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

282

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

International Nuclear Information System (INIS)

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

283

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

284

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

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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

285

Experimental Investigation on the Strength, Deformability, Failure Behavior and Acoustic Emission Locations of Red Sandstone Under Triaxial Compression  

Science.gov (United States)

Conventional triaxial compression and "reducing confining pressure" experiments were carried out for red sandstone by an MTS815 Flex Test GT rock mechanics experimental system. Our results show that the post-peak axial deformation characteristics of red sandstone changed as the confining pressure was increased from 5 to 65 MPa. Young's modulus of red sandstone increased nonlinearly with increasing confining pressure, but Poisson's ratio remained unaffected. Using our new data, the compactive and dilatant behavior, strength and failure characteristics of sandstone under triaxial compression are further discussed. For our data, the nonlinear Hoek-Brown criterion better reflects the peak strength properties than the linear Mohr-Coulomb criterion. However, the residual strength shows a clear linear relationship with confining pressure, which can be best described using the linear Mohr-Coulomb criterion. The peak and residual strengths were not directly related to the two different loading paths. The onset of dilatancy ( C'), the switch from compaction-dominated to dilatant-dominated behavior ( D') and the stress at zero volumetric strain all increased linearly with the confining pressure. In our conventional triaxial compression experiments, the failure mode changed from mixed tension and shear fracture (single shear fracture) to shear fracture with double slippage planes with increasing confining pressure. However, the failure mode in our "reducing confining pressure" experiments was more complicated and results mainly from the unstable failure characteristics of the rock during the reduction in confining pressure. Finally, based on our acoustic emission (AE) locations, at a confining pressure of 35 MPa, a detailed analysis of the evolutionary process of internal cracks is presented for the entire loading process.

Yang, Sheng-Qi; Jing, Hong-Wen; Wang, Shan-Yong

2012-07-01

286

Study on the testing method and procedures for engineering properties of NPP site : compressive strength and rock mass deformation modulus  

International Nuclear Information System (INIS)

This study have been carried out for attempting to develop the minimum requirements of testing methods and procedures for determining engineering properties for foundation bedrock at NPP site. As a first phase study, for the compressive strength and deformation modulus of rock important to the safety evaluation of the bearing capacity and settlement of the foundation, the testing methods and procedures for determining the two characteristic values were reviewed and comparison between each value of the sites under studying was carried out. The data originated from Wolsong 1 spent fuel dry storage site and the NPP sites of Yonggwang 3 · 4, Wolsong 2·3·4, and Ulchin 3·4. Also, re-evaluation was made for the data excluded from original analysis, and especially re-calculation of rock mass deformation modulus of Wolsong unit 2 was conducted by using the settlement data. The analysis result show that the uniaxial compressive and point load tests had been conducted for compressive strength and the jack test, hydraulic pressure meter test, and correlation methods using RQD, RMR, and velocity index were conducted for rock mass deformation modulus. It is also found that there was a tendency to decide characteristic values by selecting the lower value among various test results rather than considering the credibility of the test results

287

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

288

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

289

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

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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 ...

2009-01-01

290

[Study of the strength of compacts of mixed dry binders consisting of powdered cellulose and directly compressible lactose].  

Science.gov (United States)

The paper studied the strength of compacts of dry binders consisting of powdered cellulose and directly compressible lactose. The powdered cellulose employed was Arbocel A300, the directly compressible lactose, Pharmatosa DCL 21. The first step of the evaluation comprised the tensile strength of compacts and sensitivity of dry binders alone to an addition of magnesium stearate. The same method of evaluation was then used for mixed dry binders from Arbocel A300 and Pharmatosa DCL 21 in ratios of 3:1, 1:1 and 1:3. The tested concentrations of magnesium stearate were 0.4 and 0.8%. Sensitivity of dry binders to an addition of the lubricant was evaluated by means of lubricant sensitivity ratio (LSR) values. The compacts with the highest strength and at the same time the lowest sensitivity to an addition of magnesium stearate were produced using a mixture of Arbocel A300 and Pharmatosa DCL 21 in a ratio of 1:3. The evaluation also included the commercially produced mixed dry binder Cellactosa 80, in which higher sensitivity to an addition of stearate than in a mixture of Arbocel A300 and Pharmatosa DCL 21 in a ratio of 1:3 was found. PMID:15369229

Muzíková, J; Hájková, P; Vinklarová, S

2004-07-01

291

OVERVIEW OF RECENT STUDIES AT IPST ON CORRUGATED BOARD EDGE COMPRESSION STRENGTH: TESTING METHODS AND EFFECTS OF INTERFLUTE BUCKLING  

Directory of Open Access Journals (Sweden)

Full Text Available Several recent series of investigations were conducted on corrugated board performance in the areas of: loaded container endurance in cyclic humidity, predictive models for edge compression strength (ECT, effects of lightweight facings, measurement of transverse shear rigidity, effects of adhesive level, and out-of-plane crushing on ECT. The course of this program prompted exploration and review of several aspects of ECT testing methods: specimen height, test duration, and fixture-clamping effects. In this review, ECT values are shown to be influenced by the combination of the selected testing technique with the specific structural and strength characteristics of the board being tested. The effect of specimen height on selected single wall C-, E-, F-, and N-flute boards is measured and rationalized using a simplified beam-theory approach. Apparent loss of ECT in a C-flute crushed board is explored to determine whether mitigation is possible by selection or modification of testing method. Investigations of platen speed effects on C-flute substantiate previous work. Lightweight facings on A- and C-flute corrugated boards are observed to display localized buckling, which affects the ECT value. An analytical model that combines the measured bending stiffness of the facings and the compression strengths of the fluting and facings provides an improved predictive accuracy and is applied to a series of laboratory and commercial corrugated boards.

Roman Popil

2012-04-01

292

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)

293

Evaluation of compressive strength and stiffness of grouted soils by using elastic waves.  

Science.gov (United States)

Cement grouted soils, which consist of particulate soil media and cementation agents, have been widely used for the improvement of the strength and stiffness of weak ground and for the prevention of the leakage of ground water. The strength, elastic modulus, and Poisson's ratio of grouted soils have been determined by classical destructive methods. However, the performance of grouted soils depends on several parameters such as the distribution of particle size of the particulate soil media, grouting pressure, curing time, curing method, and ground water flow. In this study, elastic wave velocities are used to estimate the strength and elastic modulus, which are generally obtained by classical strength tests. Nondestructive tests by using elastic waves at small strain are conducted before and during classical strength tests at large strain. The test results are compared to identify correlations between the elastic wave velocity measured at small strain and strength and stiffness measured at large strain. The test results show that the strength and stiffness have exponential relationship with elastic wave velocities. This study demonstrates that nondestructive methods by using elastic waves may significantly improve the strength and stiffness evaluation processes of grouted soils. PMID:25025082

Lee, In-Mo; Kim, Jong-Sun; Yoon, Hyung-Koo; Lee, Jong-Sub

2014-01-01

294

Evaluation of Compressive Strength and Stiffness of Grouted Soils by Using Elastic Waves  

Science.gov (United States)

Cement grouted soils, which consist of particulate soil media and cementation agents, have been widely used for the improvement of the strength and stiffness of weak ground and for the prevention of the leakage of ground water. The strength, elastic modulus, and Poisson's ratio of grouted soils have been determined by classical destructive methods. However, the performance of grouted soils depends on several parameters such as the distribution of particle size of the particulate soil media, grouting pressure, curing time, curing method, and ground water flow. In this study, elastic wave velocities are used to estimate the strength and elastic modulus, which are generally obtained by classical strength tests. Nondestructive tests by using elastic waves at small strain are conducted before and during classical strength tests at large strain. The test results are compared to identify correlations between the elastic wave velocity measured at small strain and strength and stiffness measured at large strain. The test results show that the strength and stiffness have exponential relationship with elastic wave velocities. This study demonstrates that nondestructive methods by using elastic waves may significantly improve the strength and stiffness evaluation processes of grouted soils. PMID:25025082

Lee, In-Mo; Kim, Jong-Sun; Yoon, Hyung-Koo; Lee, Jong-Sub

2014-01-01

295

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

296

Evidence for a Long-Term Strength Threshold in Crystalline Rock  

Science.gov (United States)

The mechanical response of brittle rock to long-duration compression loading is of particular concern in underground disposal of nuclear waste, where radionuclides must be isolated from the biosphere for periods of the order of a million years. Does the strength decrease without limit over such time, or is there, for some rock types, a lower “threshold” strength below which the rock will cease to deform? This paper examines the possibility of such a threshold in silicate crystalline rocks from several perspectives, including: (1) interpretation of the results of short-term creep tests on rock; (2) numerical analysis of the effect of decrease in fracture toughness due to stress corrosion on the strength of a crystalline rock; and (3) evidence from plate tectonics, and observations of in situ rock stress in granite quarries. The study concludes that there is clear e vidence of threshold strength. The threshold is of the order of 40% of the unconfined compressive strength or higher for laboratory specimens under unconfined compressive loading, and increases rapidly in absolute value with confinement. Field evidence also leads to the conclusion that the long-term strength of crystalline rock in situ is of comparable magnitude to the laboratory value.

Damjanac, Branko; Fairhurst, Charles

2010-09-01

297

Effect of high volume of fly ash from 5 sources on compressive strength and acid resistance of concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this research was to examine the effect of high volume of fly ash from various sources on compressive strength and acid resistance of concrete. Fly ashes from 5 sources were collected and classified by an air classifier into 3 groups of different degree of fineness; low, medium, and high fineness. Portland cement type I was replaced by fly ash at the rate of 50% by weight of cementitious materials (Portland cement type I and fly ash) to cast concrete cylinders of 10 cm in diame...

Vivatanachang, N.; Homwuttiwong, S.; Jaturapitakkul, C.

2004-01-01

298

Resistencia a la compresión y reología de cementantes ambientalmente amigables / Compressive strength and rheology of environmentally-friendly binders  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Siendo la producción de cemento responsable de aproximadamente el 9% de la producción industrial de gases de invernadero, y en pro de generar materiales alternativos, en este artículo se presentan los resultados de una investigación encaminada a desarrollar cementantes que potencialmente representen [...] una alternativa ambientalmente sostenible en la construcción civil. Combinaciones de escoria granulada de alto horno, escoria de acería obtenida mediante un proceso de oxígeno básico, polvo de horno de cemento y residuo de demolición de divisiones de yeso fueron usados para optimizar la resistencia a la compresión y obtener cinco mezclas de concreto con cementantes hechos parcial o totalmente con residuos industriales. Los resultados obtenidos muestran que las resistencias de las mezclas compuestas de cemento Portland y residuos industriales son adecuadas para una cantidad importante de aplicaciones en construcción civil, y aunque para las mezclas formadas completamente por residuos industriales se presentó una importante disminución en la resistencia a la compresión, los resultados obtenidos mostraron un gran potencial para determinadas aplicaciones industriales. Adicionalmente a la resistencia a la compresión, a dichas mezclas se les determinaron sus propiedades reológicas definiendo sus características de flujo y trabajabilidad. Abstract in english Ordinary Portland cement production accounts for 9% of worldwide greenhouse gas emissions. This paper summarises the results of research aimed at developing environmentally-friendly binders which can be used as an alternative in civil construction, aimed at generating alternatives and sustainable ma [...] terials. Mixes of the combination of granulated ground blast furnace slag, basic oxygen slag, cement kiln dust and plasterboard gypsum were used for optimising the binders, according to their compressive strength, to obtain 5 concrete mixtures made partially or completely with industrial waste. The results showed that the compressive strength of mixtures of Portland cement and industrial waste were suitable for different civil construction applications and, although mixtures formed entirely from industrial waste had a significant decrease in their compressive strength, the results showed great potential for specific industrial applications. In addition to compressive strength, the rheological properties of these mixtures were determined for defining flow and workability characteristics.

Juan Manuel, Lizarazo Marriaga; Peter, Claisse.

2009-08-01

299

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

300

Resistencia a la compresión y reología de cementantes ambientalmente amigables / Compressive strength and rheology of environmentally-friendly binders  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Siendo la producción de cemento responsable de aproximadamente el 9% de la producción industrial de gases de invernadero, y en pro de generar materiales alternativos, en este artículo se presentan los resultados de una investigación encaminada a desarrollar cementantes que potencialmente representen [...] una alternativa ambientalmente sostenible en la construcción civil. Combinaciones de escoria granulada de alto horno, escoria de acería obtenida mediante un proceso de oxígeno básico, polvo de horno de cemento y residuo de demolición de divisiones de yeso fueron usados para optimizar la resistencia a la compresión y obtener cinco mezclas de concreto con cementantes hechos parcial o totalmente con residuos industriales. Los resultados obtenidos muestran que las resistencias de las mezclas compuestas de cemento Portland y residuos industriales son adecuadas para una cantidad importante de aplicaciones en construcción civil, y aunque para las mezclas formadas completamente por residuos industriales se presentó una importante disminución en la resistencia a la compresión, los resultados obtenidos mostraron un gran potencial para determinadas aplicaciones industriales. Adicionalmente a la resistencia a la compresión, a dichas mezclas se les determinaron sus propiedades reológicas definiendo sus características de flujo y trabajabilidad. Abstract in english Ordinary Portland cement production accounts for 9% of worldwide greenhouse gas emissions. This paper summarises the results of research aimed at developing environmentally-friendly binders which can be used as an alternative in civil construction, aimed at generating alternatives and sustainable ma [...] terials. Mixes of the combination of granulated ground blast furnace slag, basic oxygen slag, cement kiln dust and plasterboard gypsum were used for optimising the binders, according to their compressive strength, to obtain 5 concrete mixtures made partially or completely with industrial waste. The results showed that the compressive strength of mixtures of Portland cement and industrial waste were suitable for different civil construction applications and, although mixtures formed entirely from industrial waste had a significant decrease in their compressive strength, the results showed great potential for specific industrial applications. In addition to compressive strength, the rheological properties of these mixtures were determined for defining flow and workability characteristics.

Juan Manuel, Lizarazo Marriaga; Peter, Claisse.

 
 
 
 
301

Studies on Relationship Between Water/Binder Ratio And Compressive Strength Of High Volume Fly Ash Concrete  

Directory of Open Access Journals (Sweden)

Full Text Available Pozzolanic admixtures are generally being used along with the cement in concrete mixes so as to derive certain benefits like economy, durability, Chemical resistance in permeability etc. The use of high volumes of fly ash has become on of the current topics of research possibility promoted by the availability of a wide range of chemical and mineral admixtures. In the present experimental investigation fly ash has been used in large volumes as an additional ingredient in concrete mixes. The present experimental investigations was carried out to study the relationship between Water /Binder Ratio to Compressive strength of high volume fly ash concrete using fly ash as an additional material in the cement concrete. The studies have indicated that the high volumes fly ash used in concrete as an additional material would lead to enhanced properties in concrete and contribute towards development of high performance and high strength concrete which is the need of the hour.

Dr Sravana 1 Sarika.P 3 Dr.Srinivasa Rao 1 Dr.Seshadri Sekhar T 2 , Apparao.G 2 ,

2013-08-01

302

Comparison of compressive strength of solid and hollow pontic designs for ceramometal fixed partial dentures.  

Science.gov (United States)

A total of 60 ceramometal frameworks were subjected to compressive loading. Half of the specimens had a hollow pontic design. After the addition of porcelain, it was found that there was no significant difference in the fracture resistance of the porcelain whether the pontic was solid or hollow. PMID:3295201

Rosenstein, H E; Myers, M L; Graser, G N; Jarvis, R H

1987-06-01

303

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

304

Compressive strength and ductility of short concrete columns reinforced by bamboo  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 req...

Satjapan Leelatanon; Suthon Srivaro; Nirundorn Matan1

2010-01-01

305

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

306

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.)

307

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

308

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

CERN Document Server

A comparative analysis of toroidal, compressional and vortical dipole strengths in the spherical $^{144}$Sm and the deformed $^{154}$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 $j_{\\text{con}}$ and magnetization $j_{\\text{mag}}$ 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. In $^{154}$Sm, the $\\mu$=0 and $\\mu$=1 branches of the mode form well separated resonances. When stepping from $^{144}$Sm to $^{154}$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 signific...

Kvasil, J; Kleinig, W; Bozik, D; Reinhard, P -G; Iudice, N Lo

2013-01-01

309

Relative scale and the strength and deformability of rock masses  

Science.gov (United States)

The strength and deformation of rocks depend strongly on the degree of fracturing, which can be assessed in the field and related systematically to these properties. Appropriate Mohr envelopes obtained from the Rock Mass Rating (RMR) classification system and the Hoek-Brown criterion for outcrops and other large-scale exposures of fractured rocks show that rock-mass cohesive strength, tensile strength, and unconfined compressive strength can be reduced by as much as a factor often relative to values for the unfractured material. The rock-mass deformation modulus is also reduced relative to Young's modulus. A "cook-book" example illustrates the use of RMR in field applications. The smaller values of rock-mass strength and deformability imply that there is a particular scale of observation whose identification is critical to applying laboratory measurements and associated failure criteria to geologic structures.

Schultz, Richard A.

1996-09-01

310

Depth Variability of Compressive Strength Test Results of Toki Granite from Shobasama and Mizunami Construction Sites, Japan  

Science.gov (United States)

This paper studies the depth variability of uniaxial compressive laboratory test results on intact Toki granite (i.e., sound rock without macroscopic fractures) from the Shobasama and Mizunami Construction Sites, Japan. Some of the depth variability observed in the laboratory results can be indirectly attributed to the high fracture frequency of the “upper highly fractured rock domain” from which some of the samples were taken. For samples taken from the “lower sparsely fractured rock domain,” however, the uniaxial compressive strength of the granite seems to be very strongly correlated to the level of in situ rock stress (i.e., maximum shear stress) determined by measurement results obtained from hydrofracturing tests. The correlation between the laboratory results and the level of in situ stress is explained by the damage due to the complex stress path that the cores undergo during drilling, besides the stress concentrations at the drill-bit/rock contact, which can also affect the microcracking of the samples. An attempt to adjust laboratory test results to estimate the in situ intact rock strength of Toki granite based on its correlation with in situ stresses was carried out.

Lanaro, Flavio; Sato, Toshinori; Nakama, Shigeo

2009-08-01

311

The effects of friction on the compressive behaviour of high strength steels  

International Nuclear Information System (INIS)

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 be applied if meaningful results are to be obtained. (orig.)

312

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.

313

Nano-Meso-Macro strength analysis of low carbon austenitic stainless steels pre-strained under tension and compression loading  

International Nuclear Information System (INIS)

This report describes the nanoscopic strength analysis of low carbon austenitic stainless steel 316NG pre-strained to ±10% and ±20% true strain under tension and compression loading. This strength analysis was conducted, using an ultra-micro, micro and Vickers hardness testers and TEM. TEM observations showed that micro-structural parameters relevant the analysis are the dislocation cell size, dcel and the coarse slip band spacing, lcsl. 10dcel or 10lcsl shows the position where fine grain strengthening by dislocation cells or slip spacing saturates and the hardness becomes constant. The Vickers hardness, HV, corresponding to the micro strength was expressed as HV=H?*bas + H?*sol + H?*dis + H?*cel + H*?csl. H?*bas is the base hardness, H?*sol is the solid solution strengthening hardness, H?*dis is the dislocation strengthening hardness in the dislocation cell, and H?*cel and H?*csl are the fine grain strengthening hardness due to the dislocation cell and coarse slip band, respectively. H?*bas, H?*sol and H?*dis were about 100, 50 and 0, respectively, independently of the pre-strain of ±10% and ±20%. Accordingly, the Vickers hardness increment corresponding to the work hardening was equal to the sum of H?*cel and H?*csl. In other words, the workn other words, the work hardening due to tension and compression pre-straining up to ±20% is dominated by fine grain strengthening due to the dislocation cell and coarse slip band. This behavior was similar to that obtained in SUS316NG steel pre-stained by cold rolling in the previous study. It is concluded from those results that the work hardening mechanisms in SUS316NG steel are independent of the pre-strain method. (author)

314

Theory of DDT in unconfined flames  

CERN Document Server

This paper outlines a theoretical approach for predicting the onset of detonation in unconfined turbulent flames which is relevant both to problems of terrestrial combustion and to thermonuclear burning in Type Ia supernovae. Two basic assumuptions are made: 1) the gradient mechanism is the inherent mechanism that leads to DDT in unconfined conditions, and 2) the sole mechanism for preparing the gradient in induction time is by turbulent mixing and local flame quenching. The criterion for DDT is derived in terms of the one-dimensional detonation wave thickness, the laminar flame speed, and the laminar flame thickness in the reactive gas. This approach gives a lower-bound criterion for DDT for conditions where shock preheating, wall effects, and interactions with obstacles are absent. Regions in parameter space where unconfined DDT can and cannot occur are determined. A subsequent paper will address these issues specifically in the astrophysical context.

Khokhlov, A M; Wheeler, J C; Wheeler, J Craig

1996-01-01

315

Time-Dependent Behavior of High-Strength Concrete Under High Sustained Compressive Stresses.  

Science.gov (United States)

Results are reported of an investigation of the behavior of high-strength concrete under sustained stresses in excess of normal working stress levels. The influences of drying and of sustained stresses, ranging from 40 percent up to stress levels above wh...

M. M. Smadi

1982-01-01

316

Compressive and Flexural Strengths for Considerable Volume Fly-Ash Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

317

Modeling and analysis of porosity and compressive strength of gradient Al2O3-ZrO2 ceramic filter using BP neural network  

Directory of Open Access Journals (Sweden)

Full Text Available BP neural network was used in this study to model the porosity and the compressive strength of a gradient Al2O3-ZrO2 ceramic foam filter prepared by centrifugal slip casting. The influences of the load applied on the epispastic polystyrene template (F, the centrifugal acceleration (v and sintering temperature (T on the porosity (P and compressive strength (? of the sintered products were studied by using the registered three-layer BP model. The accuracy of the model was verified by comparing the BP model predicted results with the experimental ones. Results show that the model prediction agrees with the experimental data within a reasonable experimental error, indicating that the three-layer BP network based modeling is effective in predicting both the properties and processing parameters in designing the gradient Al2O3-ZrO2 ceramic foam filter. The prediction results show that the porosity percentage increases and compressive strength decreases with an increase in the applied load on epispastic polystyrene template. As for the influence of sintering temperature, the porosity percentage decreases monotonically with an increase in sintering temperature, yet the compressive strength first increases and then decreases slightly in a given temperature range. Furthermore, the porosity percentage changes little but the compressive strength first increases and then decreases when the centrifugal acceleration increases.

Li Qiang

2013-07-01

318

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

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

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

 
 
 
 
321

Compressive yield strength of the nanocrystalline Cu with Al2O3 dispersoid  

International Nuclear Information System (INIS)

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.

322

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

323

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

324

Non-Uniform Compressive Strength of Debonded Sandwich Panels : II. Fracture Mechanics Investigation  

DEFF Research Database (Denmark)

This article describes the development, validation and application of a FEM based numerical model for prediction of residual strength of damaged sandwich panels. The core of the theoretical method is a newly developed procedure for prediction of the propagation of a face-core debond. As demonstrated, the method can predict the maximum load carrying capacity of real-life panels with debond damages, where the failure is governed by face-sheet buckling followed by debond growth. The developed theoretical procedure is an extension of the as Crack Surface Displacement method, here denoted as the Crack Surface Displacement Extrapolation method. The method is first developed in 2D and then extended to 3D by use of a number of realistic assumptions for the considered configurations. Comparison of the theoretical predictions to a series of large-scale experiments, described in Nøkkentved et al.(2005)., shows that the model is indeed able to predict the failure modes and the residual strength of damaged panels with accuracy sufficient for practical applications. This opens up for a number of important engineering applications, for example risk-based inspection and repair schemes.

Berggreen, Carl Christian

2005-01-01

325

Modeling and analysis of porosity and compressive strength of gradient Al2O3-ZrO2 ceramic filter using BP neural network  

Digital Repository Infrastructure Vision for European Research (DRIVER)

BP neural network was used in this study to model the porosity and the compressive strength of a gradient Al2O3-ZrO2 ceramic foam filter prepared by centrifugal slip casting. The influences of the load applied on the epispastic polystyrene template (F), the centrifugal acceleration (v) and sintering temperature (T) on the porosity (P) and compressive strength (?) of the sintered products were studied by using the registered three-layer BP model. The accuracy of the model was verified by comp...

Li Qiang; Zhang Fengfeng; Yu Jingyuan

2013-01-01

326

Strain Rate Dependency of Coarse Crystal Marble Under Uniaxial Compression: Strength, Deformation and Strain Energy  

Science.gov (United States)

Strain rate during testing, uniaxial or triaxial, has important influence on the measured mechanical properties of rocks. Uniaxial compression tests were performed at nine pre-specified static-to-quasistatic strain rates (ranging from 1 × 10-5 to 1 × 10-1 s-1) on coarse crystal marble. The aim is to gain deep insight into the influence of strain rate on characteristic stresses, deformation properties and conversion of strain energy of such rock. It is found that the strain rate of 5 × 10-3 s-1 is the threshold to delineate the failure modes the tested coarse marble behaves in. At a strain rate less than this threshold, single-plane shear and conjugate X-shaped shear are the main failure modes, while beyond this threshold, extensile and splitting failures are dominant. The stress for crack initiation, the critical stress for dilation, the peak stress, and Young's modulus are all found to increase with strain rate, with an exception that the above stresses and modulus appear relatively low compared to the strain rate in the range of between 1 × 10-4 and 5 × 10-3 s-1. The pre-peak absorbed strain energy, damage strain energy and elastic strain energy are found to increase with strain rate. In addition, the elastic strain energy stored before peak point favors brittle failure of the specimen, as the more stored elastic energy in the specimen, the stronger the fragmenting.

Li, Yanrong; Huang, Da; Li, Xi'an

2014-07-01

327

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

328

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

329

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)

330

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.

331

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

332

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

Directory of Open Access Journals (Sweden)

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

333

The influence of hybridization on impact damage behavior and residual compression strength of intraply basalt/nylon hybrid composites  

International Nuclear Information System (INIS)

Highlights: ? The impact performances of basalt/nylon intraply hybrid composites were studied. ? In basalt/nylon composite, the excellent impact resistance of nylon fiber was used. ? At high impact energy, the hybrid composite have a better property than the pure ones. ? The impact property of hybrid samples is significantly affected by the fiber content. ? SEM analyses show that hybridization can prevent of catastrophic and complete failure. -- Abstract: Low-velocity impact and compression after impact (CAI) tests were performed to investigate the impact behavior of hybrid composite laminates reinforced by basalt-nylon intraply fabrics. The purpose of using this hybrid composite is to combine the good mechanical property of basalt fiber as a brittle fiber with the excellent impact resistance of nylon fiber as a ductile fiber. Five different types of woven fabric with different contents of nylon (0%, 25%, 33.3%, 50% and 100%) were used as reinforcement. The effect of nylon/basalt fiber content on impact parameters, impact damage behavior and CAI strength was studied at different nominal impact energy levels (16, 30 and 40 J). The results indicate that at low impact energy, hybridization and variation in basalt/nylon fiber content cannot improve the impact performance of composite plates. With increasing impact energy, the impact performance becomes more and more dependent on the content of nylon and basalt.

334

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

335

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

336

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

337

Application of support vector machines and relevance vector machines in predicting uniaxial compressive strength of volcanic rocks  

Science.gov (United States)

The uniaxial compressive strength (UCS) of intact rocks is an important and pertinent property for characterizing a rock mass. It is known that standard UCS tests are destructive, expensive and time-consuming task, which is particularly true for thinly bedded, highly fractured, foliated, highly porous and weak rocks. Consequently, prediction models have become an attractive alternative for engineering geologists. In the last several years, a new, alternative kernel-based technique, support vector machines (SVMs), has been popular in modeling studies. Despite superior SVM performance, this technique has certain significant, practical drawbacks. Hence, the relevance vector machines (RVMs) approach has been proposed to recast the main ideas underlying SVMs in a Bayesian context. The primary purpose of this study is to examine the applicability and capability of RVM and SVM models for predicting the UCS of volcanic rocks from NE Turkey and comparing its performance with ANN models. In these models, the porosity and P-durability index representing microstructural variables are the input parameters. The study results indicate that these methods can successfully predict the UCS for the volcanic rocks. The SVM and RVM performed better than the ANN model. When these kernel based models are considered, RVM model found successful in terms of statistical performance criterions (e.g., performance index, PI values for training and testing data are computed as 1.579 and 1.449). These values for SVM are 1.509 and 1.307. Although SVM and RVM models are powerful techniques, the RVM run time was considerably faster, and it yielded the highest accuracy.

Ceryan, Nurcihan

2014-12-01

338

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

339

Preparation of calcium aluminate cement for hard tissue repair: effects of lithium fluoride and maleic acid on setting behavior, compressive strength, and biocompatibility.  

Science.gov (United States)

We investigated lithium fluoride (LiF) and maleic acid (MA) containing calcium aluminate cement (CAC) for hard tissue repair. The objective of this study is to estimate the addition effects of LiF and MA on setting behavior, compressive strength, and biocompatibility of CAC and to find the most compatible composition of LiF and MA for using CAC as a new bone cement. The CAC was composed mainly of CaO. Al(2)O(3). Samples of LiF and MA containing CAC were formed along with recording of setting time and peak temperature and then set cement was analyzed by X-ray diffraction (XRD). Agar diffusion test, tetrazolium bromide (MTT) assay, and hemolysis test were used to detect initial in vitro biocompatibility of LiF and MA containing CAC. It was revealed from the results that LiF shortened setting time and decreased compressive strength, whereas MA delayed setting time and increased compressive strength. However, LiF and MA showed no or little influence on maximum temperature of CAC. CAC containing 0.5 g of LiF and 8.75 g of MA showed the highest compressive strength (111.64 +/- 7.74 MPa) across all the experimental compositions. The CACs containing 0.5 g of LiF/8.75 g of MA and 1.01 g LiF/8.75 g of MA had no cytotoxicity and hemolysis. In this study, CAC with 0.5 g of LiF and 8.75g of MA showed the most compatible properties for using bone cement, and thus it was assessed a candidate for a new bone cement along with CAC. PMID:12221708

Oh, Seung-Han; Choi, Se-Young; Lee, Yong-Keun; Kim, Kyoung Nam

2002-12-15

340

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

 
 
 
 
341

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

342

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.

343

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

344

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 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.

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

1999-11-08

345

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

346

New phosphate-based binder for stabilization of soils contaminated with heavy metals: leaching, strength and microstructure characterization.  

Science.gov (United States)

Cement stabilization is used extensively to remediate soils contaminated with heavy metals. However, previous studies suggest that the elevated zinc (Zn) and lead (Pb) concentrations in the contaminated soils would substantially retard the cement hydration, leading to the deterioration of the performance of cement stabilized soils. This study presents a new binder, KMP, composed of oxalic acid-activated phosphate rock, monopotassium phosphate and reactive magnesia. The effectiveness of stabilization using this binder is investigated on soils spiked with Zn and Pb, individually and together. Several series of tests are conducted including toxicity characteristic leaching (TCLP), ecotoxicity in terms of luminescent bacteria test and unconfined compressive strength. The leachability of a field Zn- and Pb- contaminated soil stabilized with KMP is also evaluated by TCLP leaching test. The results show that the leached Zn concentrations are lower than the China MEP regulatory limit except when Zn and Pb coexist and for the curing time of 7 days. On the other hand, the leached Pb concentrations for stabilized soils with Pb alone or mixed Zn and Pb contamination are much lower than the China MEP or USEPA regulatory limit, irrespective of the curing time. The luminescent bacteria test results show that the toxicity of the stabilized soils has been reduced considerably and is classified as slightly toxic class. The unconfined compressive strength of the soils decrease with the increase in the Zn concentration. The stabilized soils with mixed Zn and Pb contaminants exhibit notably higher leached Zn concentration, while there is lower unconfined compressive strength relative to the soils when contaminated with Zn alone. The X-ray diffraction and scanning electron microscope analyses reveal the presence of bobierrite (Mg3(PO4)2·8H2O) and K-struvite (MgKPO4·6H2O) as the main products formed in the KMP stabilized uncontaminated soils; the formation of hopeite (Zn3(PO4)2·4H2O), scholzite (CaZn2(PO4)2·2H2O), zinc hydroxide (Zn(OH)2), and fluoropyromorphite (Pb5(PO4)3F) in the soils are the main mechanisms for immobilization of Zn and Pb with the KMP binder. The change in the relative quantities of the formed phosphate-based products, with respect to the Zn concentration and presence of mixed Zn and Pb contaminants, can well explain the measured impact of the Zn concentration levels and presence of both Zn and Pb contaminants on the unconfined compressive strength of the KMP stabilized soils. PMID:25173726

Du, Yan-Jun; Wei, Ming-Li; Reddy, Krishna R; Jin, Fei; Wu, Hao-Liang; Liu, Zhi-Bin

2014-12-15

347

Compression of silver in a diamond anvil cell: Pressure dependences of strength and grain size from X-ray diffraction data  

Energy Technology Data Exchange (ETDEWEB)

Two silver samples, coarse grained (c-Ag, grain size 300{+-}30 nm) and nanocrystalline (n-Ag, grain size 55{+-}6 nm), are compressed in a diamond anvil cell in separate experiments. The pressure is increased in steps of {approx}3 GPa and the diffraction pattern recorded at each pressure. The grain size and compressive strength are determined from the analysis of the diffraction line-widths. The grain size of c-Ag decreases rapidly from 300{+-}30 nm at ambient pressure to 40{+-}8 nm at 15 GPa, and then gradually to 20{+-}3 nm at 40 GPa. After pressure release to ambient condition, the grain size is 25{+-}4 nm. The strength at ambient pressure is 0.18{+-}0.05 GPa and increases to 1.0{+-}0.3 GPa at 40 GPa. The grain size of n-Ag decreases from 55{+-}6 nm at ambient pressure to 17{+-}4 nm at 15 GPa and to 14{+-}3 nm at 55 GPa. After release of pressure to ambient condition, the grain size is 50{+-}7 nm. The strength increases from 0.51{+-}0.07 GPa at ambient pressure to 3.5{+-}0.4 GPa at 55 GPa. The strength is found to vary as the inverse of the square-root of the grain size. The results of the present measurements agree well with the grain-size dependence of strength derived from the hardness versus grain size data at ambient pressure available in the literature.

Liermann, Hanns-Peter; Jain, Anjana; Singh, Anil K.; Saxena, Surendra K. (NAL); (FIU); (CIW)

2010-10-22

348

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

349

Conditions pertaining to the influence of electrode surface roughness upon the insulation strength of compressed SF6 systems  

DEFF Research Database (Denmark)

On the basis of a series of experimental investigations reported in the literature, electrode microscopic surface roughness was dismissed as a factor influencing breakdown levels in compressed SF6, irrespective of field non-uniformity. This conclusion appears to be tenable if one restricts observations to the investigations in question. In the present communication, we contend that the scope of these studies formed an insufficient basis on which to invoke such a general conclusion. To clarify this contention, the role of surface roughness in relation to the breakdown characteristics of compressed SF6 is recalled and its domain of influence brought into focus.

McAllister, Iain Wilson; Crichton, George C

1997-01-01

350

Ideal shear strength under compression and tension in C, Si, Ge, and cubic SiC: an ab initio density functional theory study  

International Nuclear Information System (INIS)

Ideal shear strength under superimposed normal stress of cubic covalent crystals (C, Si, Ge, and SiC) is evaluated by ab initio density functional theory calculation. Shear directions in [11 2-bar] and [1 1-bar 0] on the (111) plane are examined. The critical shear stress along the former direction is lower than that along the latter in all the crystals unless the hydrostatic tension is extremely high. In both the [11 2-bar]-shear and [1 1-bar 0]-shear, critical shear stress is increased by compression in C but is decreased in the other crystals. The different response of the critical shear stress to normal stress is due to the strength of the bond-order term, i.e. dependence of the short-range interatomic attraction on the bond-angle. (paper)

351

Unconfined versus confined speleogenetic settings: variations of solution porosity  

Directory of Open Access Journals (Sweden)

Full Text Available 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 and confined settings by the analysis of morphometric parameters of typical cave patterns. Two samples of typical cave systems formed in the respective settings are compared. The sample that represents unconfined speleogenesis consists of solely limestone caves, whereas gypsum caves of this type tend to be less dendritic. The sample that represents confined speleogenesis consists of both limestone and gypsum maze caves. The comparison shows considerable differences in average values of some parameters between the settings. Passage network density (the ratio of the cave length to the area of the cave field, km/km2 is one order of magnitude greater in confined settings than in unconfined (average 167.3 km/km2 versus 16.6 km/km2. Similarly, an order of magnitude difference 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 settings than in unconfined (29.7 % versus 6.4 %. This indicates that conduit permeability in confined aquifers is appreciably easier to target with drilling than the widely spaced conduits in unconfined aquifers.

Klimchouk, A.B.

2003-01-01

352

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

353

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

Science.gov (United States)

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

Sim, Jongsung; Park, Cheolwoo

2011-11-01

354

Effect of Superplasticizer and Extra Water on Workability and Compressive Strength of Self-Compacting Geopolymer Concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study documents the results of an experimental work carried out to investigate the effect of superplasticizer and amount of extra water on strength and workability properties of Fly ash-based Selfcompacting geopolymer concrete. The experiments were conducted by varying the amount of extra water and dosage of superplasticizer. A total of nine mixtures with superplasticizer content varying from 3 to 7% and extra water ranging from 10 to 20% of the mass of fly ash were prepared and tested. ...

Fareed Ahmed Memon; Muhd Fadhil Nuruddin; Samuel Demie; Nasir Shafiq

2012-01-01

355

Study Of Compressibility Corrections To Turbulence Models  

Science.gov (United States)

Effects on shear layers in simulated confined and unconfined flows studied. Report presents comparative study of some terms that correct for effects of compressibility in standard k-epsilon mathematical model of turbulence where k denotes turbulence kinetic energy and epsilon denotes rate of dissipation of turbulence kenetic energy. Involved simulation of flows by numerical solution of Reynolds-averaged Navier-Stokes equations.

Viegas, J. R.; Rubesin, M. W.

1993-01-01

356

Stability of Strength and Deformation Characteristics of Expanded Polystyrene (EPS within the Time of Long-Term Investigation of Creep Strain under Permanent Compressive Loading  

Directory of Open Access Journals (Sweden)

Full Text Available The results of investigation of strength (s10 %, scr and deformability (E characteristics of expanded polystyrene specimens are presented. The results are based on the short-term compression in the organization of long-term creep study. For the experiments identical specimens stored 5 years at ambient temperature (23 ±2 °C and relative humidity (50 ±5 % as well specimens after removal long-term loading were used. There were established, that difference between experimental values of stress and initial modulus of tested expanded polystyrene specimens with confidence probability P = 90 % (on-sided test is negligible (random.DOI: http://dx.doi.org/10.5755/j01.ms.19.2.4442

Saulius VAITKUS

2013-05-01

357

Anhydrite binders in mining. Part 3. Effects of water-anhydrite index, activator and expansor on consistence, setting velocity, immediate compression strength and expansion range of binding materials  

Energy Technology Data Exchange (ETDEWEB)

On the basis of investigations carried out by the Institute of Mine Design, Construction and Ground Surface Protection of the Silesian Technical University analyzes physical and mechanical properties of anhydrite binders used for strata control, grouting, packing, stowing and construction of ventilation barriers in underground coal mines in Poland. The following types of anhydrite binders are comparatively evaluated: anhydrite dust, anhydrite binder activated by sodium hydroxide (not exceeding 2%), anhydrite binder activated by calcium oxide (2%), anhydrite binder activated by sodium carbonate (2%), expansive anhydrite binder with sodium bicarbonate (2%), expansive binder with 4% sodium bicarbonate (expansive agent) and 2% calcium hydroxide (activating agent), expansive binder with 2.5% sodium bicarbonate (expansive agent) and 0.5% sodium hydroxide (activating agent). Effects of types and concentration ratio of activating and expanding reagents as well as water to anhydrite ratio on immediate and final compression strength and porosity of anhydrite binders are analyzed. 7 refs.

Chudek, M.; Janiczek, S.; Majchrzak, R.

1988-09-01

358

Three-dimensional groundwater velocity field in an unconfined aquifer under irrigation  

International Nuclear Information System (INIS)

A method for three-dimensional flow velocity calculation has been developed to evaluate unconfined aquifer sensitivity to areal agricultural contamination of groundwater. The methodology of Polubarinova-Kochina is applied to an unconfined homogeneous compressible or incompressible anisotropic aquifer. It is based on a three-dimensional groundwater flow model with a boundary condition on the moving surface. Analytical solutions are obtained for a hydraulic head under the influence of areal sources of circular and rectangular shape using integral transforms. Two-dimensional Hantush formulas result from the vertical averaging of the three-dimensional solutions, and the asymptotic behavior of solutions is analyzed. Analytical expressions for flow velocity components are obtained from the gradient of the hydraulic head field. Areal and temporal variability of specific yield in groundwater recharge areas is also taken into account. As a consequence of linearization of the boundary condition, the operation of any irrigation system with respect to groundwater is represented by superposition of the operating wells and circular and rectangular source influences. Combining the obtained solutions with Dagan or Neuman well functions, one can develop computer codes for the analytical computation of the three-dimensional groundwater hydraulic head and velocity component distributions. Methods for practical implementation are discussed. (Auth

359

The compression strength investigations of AW-AlCu4Mg2Mn alloy based composites reinforced with SiC particles  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper strength tests of composite materials based on AW-AlCu4Mg2Mn obtained in uniaxial compression test was studied.Materials used for examination were made from AW-AlCu4Mg2Mn alloy and porous preforms of SiC particles (grain size 6÷10?m bypressure infiltration (squeeze casting. The stress-strain curves of the materials with 10% vol., 20% vol., 30% vol. particles of SiC, as well unreinforcement alloy and microstructure of scrap surface samples in a plane parallel to the compressive force were analyzed. The investigated metal matrix composites are characterized by marked reduced the plastic strain values with increasing particle strengthening while the unreinforcement materials throughout the range of deformation show considerable plasticity. In the case of the material containing 10% vol of SiC the plastic strain is a slight strengthening of the material. With increasing of the particle content the plasticity decreases. Materials with 20%vol and 30%vol of SiC particles were brittle cracked at much higher values of stress ?.

A. Kurzawa

2011-04-01

360

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

 
 
 
 
361

Size effect on strength and strain hardening of small-scale [1 1 1] nickel compression pillars  

International Nuclear Information System (INIS)

This study investigates uniaxial compression behavior of focused ion beam (FIB) manufactured [1 1 1] nickel (Ni) small-scale pillars, ranging in diameter from approximately 25 ?m to below 200 nm, in order to examine the effect of crystallographic orientation on the mechanical properties. This study is unique from other micro-pillar studies in that the [1 1 1] orientation has a considerably lower Schmid factor, and has multiple slip systems available. The [1 1 1] Ni pillars show a strong increase in yield stress and work hardening with decreasing diameter. The relationship between yield stress and diameter (?y ? d-0.69) matches well with previous small-scale pillar studies. Strain hardening, which has been inconsistently observed in other micro-pillar studies, is found to be a function of both diameter and orientation. Although the precise mechanism for hardening is unknown, transmission electron microscopy reveals dislocations throughout the pillar and into the base material suggesting that dislocation interactions and deformation below the pillar play a role in the observed strain hardening. Furthermore, a slight crystallographic rotation of the pillar is observed likely contributing to the observed mechanical properties. By exploring the role of crystallography on the plastic deformation behavior, this study provides additional insight into the nature of the size effect

362

Bivariate genome-wide association study suggests fatty acid desaturase genes and cadherin DCHS2 for variation of both compressive strength index and appendicular lean mass in males.  

Science.gov (United States)

Compressive strength index (CSI) is a newly established index for predicting hip fracture, the most serious consequence of osteoporosis. Appendicular lean mass (ALM), which influences skeletal strength of the lower limbs, is another trait associated with the risk of hip fracture. In this study, we performed a bivariate genome-wide association study (GWAS) to identify new candidate genes responsible for both CSI and ALM. In our discovery sample of 1627 unrelated Chinese subjects (802 males and 825 females), we scanned 909,509 SNPs using the Affymetrix Human Genome SNP 6.0 genotyping array. We successfully replicated our results in a sample of 2286 Caucasian subjects (558 males and 1728 females). The results indicated that five SNPs (rs174583, rs174577, rs174549, rs174548, rs7672337) in the FADS1, FADS2, and DCHS2 genes had significant bivariate associations with CSI and ALM in male subjects for both the GWAS discovery (with PFADS1, FADS2, and DCHS2, containing these SNPs might play dual roles influencing both CSI and ALM in males. Our findings provide new insights into our understanding of the genetic basis of bone metabolism and the pathogenesis of osteoporosis. PMID:22960237

Han, Yingying; Pei, Yufang; Liu, Yaozhong; Zhang, Lei; Wu, Shuyan; Tian, Qing; Chen, Xiangding; Shen, Hui; Zhu, Xuezhen; Papasian, Christopher J; Deng, Hongwen

2012-12-01

363

Probe penetration test applied for evaluating shotcrete compressive strength / Ensaio de penetração de pino aplicado na avaliação da resistência à compressão de concreto projetado  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este trabalho visa apresentar uma metodologia de avaliação da resistência à compressão de concreto projetado. Em função da elevada rugosidade superficial e da baixa espessura da camada de concreto, observada em estruturas de concreto projetado, a metodologia proposta tem por base o ensaio de penetra [...] ção de pinos. Em uma primeira etapa, a variabilidade do ensaio de penetração de pinos foi investigada de modo a definir a quantidade de ensaios necessários para a definição da curva de correlação do ensaio. Em seguida, o procedimento empregado na definição da curva de correlação foi definido. Tal procedimento inclui a moldagem de placas de concreto projetado in loco; o controle da energia de disparo dos pinos; a extração de testemunhos das placas para determinação da resistência à compressão do concreto; e a análise estatística dos dados. De posse da curva de correlação do ensaio, procede-se com a avaliação da estrutura e análise dos dados. De modo a verificar a aplicabilidade da metodologia proposta, a estrutura de concreto projetado de um túnel em uma Pequena Usina Hidrelétrica foi investigada. Na estrutra em questão, foram observados resultados de resistência não-conformes com as especificações de projeto e indícios de falta de homogeneidade do concreto. Uma vez que a metodologia em questão possibilitou a caracterização das condições da estrutura avaliada, pode-se afirmar que a solução proposta neste trabalho é adequada para a avaliação da resistência à compressão de estruturas de concreto projetado. Abstract in english This study presents a methodology for evaluating shotcrete compressive strength. Because of the high surface roughness and low thickness of the concrete layer observed in shotcrete structures, the proposed methodology is based on the probe penetration test. In a first phase, the variability of the p [...] robe penetration test was investigated to define the number of tests that are required to characterise the test correlation curve. Then, a procedure that can be applied to define the correlation curve was described. This procedure includes the moulding of shotcrete plates in loco, the control of the discharge energy of the pins, the extraction of the plates' samples to determine the concrete compressive strength, and statistical analysis. With the test correlation curve, an evaluation of the structure and data analysis can be performed. To verify the applicability of the proposed methodology, the structure of a shotcrete tunnel in a small hydropower plant was investigated. In the analysed structure, strength results that were non-compliant with the project specifications and a lack of concrete homogeneity were observed. Since the analysed methodology allowed for the characterisation of the considered structure conditions, the proposed solution is adequate for evaluating the compression strength of shotcrete structures.

W. R. L. da, Silva; L. R., Prudencio Jr; A. L. de, Oliveira.

364

Controlled low-strength material using fly ash and AMD sludge.  

Science.gov (United States)

Controlled low-strength material (CLSM) is a cementitious material with properties similar to stabilized soil. After hardening, CLSM provides adequate strength in bearing capacity and support but can also be easily excavated. To be classified as a CLSM, the material must have a compressive strength between 450 kPa (65 psi) and 8400 kPa (1200 psi). Typical CLSM contains coal-combustion fly ash (FA), cement, water and fine or coarse aggregate. In this paper, physical and strength properties of CLSM formed by combining sludge, a by-product from the treatment of acid mine drainage (AMD), with Class F FA are investigated. The sludge is a lime-based waste product that when combined with FA, exhibits self-hardening characteristics similar to cement. A main focus of this research is to develop a CLSM mix in which by-product material utilization is maximized while satisfying workability and performance requirements. A mixture of 10% AMD sludge, 2.5% Portland cement (PC), 87.5% Class F FA (dry wt.%) with water provided unconfined compressive strength values within the range for classification as CLSM. This mixture satisfies the excavatability and walkability requirements as well as the hardening time and stability criteria. PMID:10936537

Gabr, M A; Bowders, J J

2000-09-15

365

The Australian Paleoflood Model for Unconfined Fluvial Deposition on Mars  

Science.gov (United States)

Paleoflood deposits in central Australia represent a new model for possible fluvial deposits on Mars. The distinct Australian assemblage of landforms and sediments is used to identify potential unconfined paleoflood deposits in Mars Orbiter Camera (MOC) images of Mars. Additional information is contained in the original extended abstract.

Bourke, M. C.; Zimbelman, J. R.

2001-01-01

366

Resistência à compressão de argamassas em função da adição de fibra de coco / Compressive strength of cement mortar prepared with the addition of coconut fiber  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Neste trabalho se propôs analisar a influência que a variação do comprimento da fibra de coco exerce na resistência à compressão da argamassa, em busca de se determinar, experimentalmente, o comprimento mais próximo ao tamanho crítico. Foram confeccionadas argamassas com adição (0,3% em relação ao v [...] olume total da mistura) de 6 comprimentos diferentes de fibras de coco: 12,5; 25,0; 37,5; 50,0; 62,5 e 75,0 mm, além de uma argamassa de referência sem adição de fibra de coco. Para a avaliação do comportamento de cada um deles na argamassa foram efetuados ensaios de consistência no estado fresco e resistência à compressão axial no estado endurecido, realizado nas idades 7, 28 e 56 dias, ao longo do primeiro semestre de 2013. Foi observado que todos os comprimentos de fibra testados diminuem a resistência à compressão em relação à argamassa de referência, nas três idades. No entanto, dentre esses comprimentos testados, pode-se afirmar que a argamassa com adição de fibras de comprimento 25,0 mm obteve melhor desempenho nas três idades testadas. Abstract in english This paper aims to analyse the influence that the length of coconut fiber exerts on compressive strength of mortar seeking to determine their critical length. Mortars were prepared with addition (0.3% volume of the mixture) of 6 different lengths of coconut fibers: 12.5, 25.0, 37.5, 50.0, 62.5 and 7 [...] 5.0 mm, and a reference mortar. To study the behavior of each one in mortar, consistency tests were performed on fresh and hard state in axial compression strength test at three ages (7, 28 and 56 days) during the first half of 2013. It was observed that all lengths tested decrease resistance compared to the reference mortar in three ages, however, the mortar with addition of 25.0 mm length fibers had a better performance in the study.

Everton J. da, Silva; Paola D. da, Silva; Maria L., Marques; Celso C. M., Fornari Junior; Fermin C., Garcia; Francisco H. M., Luzardo.

1268-12-01

367

Effect of Microwave Treatment on Oak Compression Strength / Effet du Traitement du Bois de Chêne par des Ultrasons sur la Résistance à la Compression / Efeito na Resistência à Compressão do Tratamento de Madeira de Carvalho com Ultra-Sons  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in portuguese A energia de microondas (electromagnética) é actualmente utilizada no tratamento de degradação biológica e na classificação mecânica de madeira e perspectiva-se a sua utilização na secagem de madeira. A exposição a microondas de elementos estruturais de madeira implica, tal como para outros processo [...] s de preparação da madeira (preservação ou tratamentos ignífugos), analisar o efeito dessa exposição nas propriedades mecânicas da madeira. O presente artigo pretende contribuir para esta discussão, apresentando um estudo preliminar sobre o efeito da exposição a microondas (durante 5 e 10min) na resistência à compressão paralela às fibras de madeira de Carvalho limpa de defeitos. Os resultados obtidos mostram uma clara perda de resistência com a exposição e aumento do tempo de exposição. Considerando os resultados obtidos no presente estudo e por outros autores, torna-se clara a necessidade de estudos mais exaustivos tendo em vista estabelecer possíveis factores de correcção ou regras de utilização segura desta energia de forma a garantir um apropriado comportamento mecânico da madeira. Abstract in english Microwave (electromagnetic) energy is currently used in the treatment of biological damage, in the machine grading of timber and its use for timber drying is foreseen. The exposure of structural timber elements to microwaves, such as for other timber treatments (preservation or fire-retardant), impl [...] ies analyzing its effect on the mechanical properties of the wood. This paper intends to contribute to this discussion, presenting a preliminary study on the effect of microwave exposure (during 5 and 10min) on compression parallel to grain strength of clear Oak wood. The results obtained show a clear loss of strength due to exposure and to an increase in the time of exposure. Considering the results obtained in this study and by other authors, it becomes clear that more thorough research is needed, bearing in mind the establishment of strength correction factors or rules towards the safe use of this technology for assuring the proper mechanical behaviour of timber.

José Saporiti, Machado.

2006-06-01

368

Effect of Microwave Treatment on Oak Compression Strength / Effet du Traitement du Bois de Chêne par des Ultrasons sur la Résistance à la Compression / Efeito na Resistência à Compressão do Tratamento de Madeira de Carvalho com Ultra-Sons  

Scientific Electronic Library Online (English)

Full Text Available SciELO Portugal | Language: English Abstract in portuguese A energia de microondas (electromagnética) é actualmente utilizada no tratamento de degradação biológica e na classificação mecânica de madeira e perspectiva-se a sua utilização na secagem de madeira. A exposição a microondas de elementos estruturais de madeira implica, tal como para outros processo [...] s de preparação da madeira (preservação ou tratamentos ignífugos), analisar o efeito dessa exposição nas propriedades mecânicas da madeira. O presente artigo pretende contribuir para esta discussão, apresentando um estudo preliminar sobre o efeito da exposição a microondas (durante 5 e 10min) na resistência à compressão paralela às fibras de madeira de Carvalho limpa de defeitos. Os resultados obtidos mostram uma clara perda de resistência com a exposição e aumento do tempo de exposição. Considerando os resultados obtidos no presente estudo e por outros autores, torna-se clara a necessidade de estudos mais exaustivos tendo em vista estabelecer possíveis factores de correcção ou regras de utilização segura desta energia de forma a garantir um apropriado comportamento mecânico da madeira. Abstract in english Microwave (electromagnetic) energy is currently used in the treatment of biological damage, in the machine grading of timber and its use for timber drying is foreseen. The exposure of structural timber elements to microwaves, such as for other timber treatments (preservation or fire-retardant), impl [...] ies analyzing its effect on the mechanical properties of the wood. This paper intends to contribute to this discussion, presenting a preliminary study on the effect of microwave exposure (during 5 and 10min) on compression parallel to grain strength of clear Oak wood. The results obtained show a clear loss of strength due to exposure and to an increase in the time of exposure. Considering the results obtained in this study and by other authors, it becomes clear that more thorough research is needed, bearing in mind the establishment of strength correction factors or rules toward