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1

Dataset of the relationship between unconfined compressive strength and tensile strength of rock mass  

Energy Technology Data Exchange (ETDEWEB)

This report summary the dataset of the relationship between unconfined compressive strength and tensile strength of the rock mass described in supporting report 2; repository design and engineering technology of second progress report (H12 report) on research and development for the geological disposal of HLW in Japan. (author)

Sugita, Yutaka; Yui, Mikazu [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works

2002-02-01

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 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 25"0C and 100"0C; time, 3.5 x 10"3s and 950 x 10"3s (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

1987-01-01

4

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 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)

2008-01-01

5

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

Energy Technology Data Exchange (ETDEWEB)

K-Basin sludge will be stored in the Sludge Transport and Storage Containers (STSCs) at an interim storage location on Central Plateau before being treated and packaged for disposal. During the storage period, sludge in the STSCs may consolidate/agglomerate, potentially resulting in high-shear-strength material. The Sludge Treatment Project (STP) plans to use water jets to retrieve K-Basin sludge after the interim storage. STP has identified shear strength to be a key parameter that should be bounded to verify the operability and performance of sludge retrieval systems. Determining the range of sludge shear strength is important to gain high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from the STSCs. The shear strength measurements will provide a basis for bounding sludge properties for mobilization and erosion. Thus, it is also important to develop potential simulants to investigate these phenomena. Long-term sludge storage tests conducted by Pacific Northwest National Laboratory (PNNL) show that high-uranium-content K-Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has 'paste' and 'chunks' with shear strengths of approximately 3-5 kPa and 380-770 kPa, respectively. High-uranium-content sludge samples subjected to hydrothermal testing (e.g., 185 C, 10 hours) have been observed to form agglomerates with a shear strength up to 170 kPa. These high values were estimated by measured unconfined compressive strength (UCS) obtained with a pocket penetrometer. Due to its ease of use, it is anticipated that a pocket penetrometer will be used to acquire additional shear strength data from archived K-Basin sludge samples stored at the PNNL Radiochemical Processing Laboratory (RPL) hot cells. It is uncertain whether the pocket penetrometer provides accurate shear strength measurements of the material. To assess the bounding material strength and potential for erosion, it is important to compare the measured shear strength to penetrometer measurements and to develop a correlation (or correlations) between UCS measured by a pocket penetrometer and direct shear strength measurements for various homogeneous and heterogeneous simulants. This study developed 11 homogeneous simulants, whose shear strengths vary from 4 to 170 kPa. With these simulants, we developed correlations between UCS measured by a Geotest E-280 pocket penetrometer and shear strength values measured by a Geonor H-60 hand-held vane tester and a more sophisticated bench-top unit, the Haake M5 rheometer. This was achieved with side-by-side measurements of the shear strength and UCS of the homogeneous simulants. The homogeneous simulants developed under this study consist of kaolin clay, plaster of Paris, and amorphous alumina CP-5 with water. The simulants also include modeling clay. The shear strength of most of these simulants is sensitive to various factors, including the simulant size, the intensity of mixing, and the curing time, even with given concentrations of simulant components. Table S.1 summarizes these 11 simulants and their shear strengths.

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

2011-02-20

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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.

7

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.

8

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 Mateus

2008-01-01

9

Behavior of Stabilized Peat Soils in Unconfined Compression Tests  

Directory of Open Access Journals (Sweden)

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

Wong L. Sing

2008-01-01

10

Poroviscoelastic modeling of liver biomechanical response in unconfined compression.  

Science.gov (United States)

Mechanistic modeling approaches are important for understanding how fluid and solid components of the liver interact during impact trauma. This study uses poroviscoelasticity (PVE) theory to simulate liver biomechanical response in unconfined compression stress relaxation experiments, for variable ramp strain rates ranging from 0.001 to 0.1 s(-1). Specimens included 17 ex vivo porcine liver samples tested in a humidified temperature-controlled chamber. Liver response was modeled using ABAQUS, and best-fit parameters were determined using non-linear least-squares algorithms. The PVE model was able to capture the behavior of porcine liver in unconfined compression, with regression analyses for the ramp phase demonstrating high correlation between model and experiment (R(2) > 0.993, slope > 0.833, p dummies, and improved vehicle safety. PMID:20177783

Raghunathan, Smitha; Evans, Douglas; Sparks, Jessica L

2010-05-01

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Determination of Friction Coefficient in Unconfined Compression of Brain Tissue  

CERN Multimedia

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

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

2013-01-01

12

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

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Behavior of Stabilized Peat Soils in Unconfined Compression Tests  

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Problem statement: Deep stabilized peat columns were known to be economical at forming foundations to support highway embankments constructed on deep peat land. However, failure in the formation of the columns with adequate strength was often attributed to unsuitable type and insufficient dosage of binder added to the soil. Organic matter in peat was known to impede the cementing process in the soil, thus retarding the early strength gain of stabilized peat. Approach: To evaluat...

2008-01-01

14

Single unconfined compression of cellular dense collagen scaffolds for cartilage and bone tissue engineering  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cell seeded collagen matrix scaffolds have been extensively evaluated recently as potential systems for de-novo tissue regeneration and repair for a variety of tissue types. While collagen gels are biologically excellent as starting point scaffold materials, their use is limited by the lack of cohesive structure and inherently weak mechanical properties due to a high liquid content (>99%). An ingenious method of combining unconfined plastic compression (PC) with capillary action has shown tha...

Bohr, A.; Memarzadeh, K.; Alp, B.; Brown, R.; Salih, V.

2009-01-01

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

Science.gov (United States)

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

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

1999-06-01

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

International Nuclear Information System (INIS)

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

1993-01-01

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A Comparison of the Mechanical Properties of the Goat Temporomandibular Joint Disc to the Mandibular Condylar Cartilage in Unconfined Compression  

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The aim of this study was to make a comparison of the compressive properties of the goat temporomandibular joint (TMJ) disc to the mandibular condylar cartilage (MCC) and to explore the transversely isotropic biphasic model. Samples taken mediolaterally from three regions of the TMJ disc and MCC were tested in unconfined compression at strain levels ranging from 10% to 50% and then assessed for biochemical content. The results indicated that the TMJ disc exhibits a significantly greater ta...

Hagandora, Catherine K.; Chase, Thomas W.; Almarza, Alejandro J.

2011-01-01

18

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

2010-01-01

19

Effect of strain rate on the material properties of human liver parenchyma in unconfined compression.  

Science.gov (United States)

The liver is one of the most frequently injured organs in abdominal trauma. Although motor vehicle collisions are the most common cause of liver injuries, current anthropomorphic test devices are not equipped to predict the risk of sustaining abdominal organ injuries. Consequently, researchers rely on finite element models to assess the potential risk of injury to abdominal organs such as the liver. These models must be validated based on appropriate biomechanical data in order to accurately assess injury risk. This study presents a total of 36 uniaxial unconfined compression tests performed on fresh human liver parenchyma within 48?h of death. Each specimen was tested once to failure at one of four loading rates (0.012, 0.106, 1.036, and 10.708?s-1) in order to investigate the effects of loading rate on the compressive failure properties of human liver parenchyma. The results of this study showed that the response of human liver parenchyma is both nonlinear and rate dependent. Specifically, failure stress significantly increased with increased loading rate, while failure strain significantly decreased with increased loading rate. The failure stress and failure strain for all liver parenchyma specimens ranged from -38.9?kPa to -145.9?kPa and from -0.48 strain to -1.15 strain, respectively. Overall, this study provides novel biomechanical data that can be used in the development of rate dependent material models and the identification of tissue-level tolerance values, which are critical to the validation of finite element models used to assess injury risk. PMID:23775282

Kemper, Andrew R; Santago, Anthony C; Stitzel, Joel D; Sparks, Jessica L; Duma, Stefan M

2013-10-01

20

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

 
 
 
 
21

A comparison of the mechanical properties of the goat temporomandibular joint disc to the mandibular condylar cartilage in unconfined compression.  

Science.gov (United States)

The aim of this study was to make a comparison of the compressive properties of the goat temporomandibular joint (TMJ) disc to the mandibular condylar cartilage (MCC) and to explore the transversely isotropic biphasic model. Samples taken mediolaterally from three regions of the TMJ disc and MCC were tested in unconfined compression at strain levels ranging from 10% to 50% and then assessed for biochemical content. The results indicated that the TMJ disc exhibits a significantly greater tangent modulus than the MCC from 20% to 50% strain with values ranging from 729 ± 267 to 2413 ± 406?kPa and 363 ± 169 to 1677 ± 538?kPa, respectively (P < .05). The collagen content of the TMJ disc was significantly greater than the MCC, while the opposite held for the glycosaminoglycan (GAG) and DNA content. The results emphasize fundamental differences between the articulating tissues of the TMJ. PMID:21765875

Hagandora, Catherine K; Chase, Thomas W; Almarza, Alejandro J

2011-01-01

22

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

23

Compressive Strength of Autoclaved Aerated Concrete Blockwork  

Digital Repository Infrastructure Vision for European Research (DRIVER)

One of the basic problems in the design of masonry structures is the calculation of the compressive strength of masonry walls. This paper discusses the various parameters which affect the compressive strength of Autoclaved Aerated concrete blockwork with particular reference to the British Standard BS 5628: Part 1 and the Draft Eurocode EC6. Thirty six blockwork wallettes made of Autoclaved Aerated concrete blockwork were built and tested together with the corresponding properties of the unit...

Daou, Y. A.

2001-01-01

24

Compressive Strength of Autoclaved Aerated Concrete Blockwork  

Directory of Open Access Journals (Sweden)

Full Text Available One of the basic problems in the design of masonry structures is the calculation of the compressive strength of masonry walls. This paper discusses the various parameters which affect the compressive strength of Autoclaved Aerated concrete blockwork with particular reference to the British Standard BS 5628: Part 1 and the Draft Eurocode EC6. Thirty six blockwork wallettes made of Autoclaved Aerated concrete blockwork were built and tested together with the corresponding properties of the units. The parameters examined were unit strength, mortar strength and size of the units. For the range of the block width (i.e. 100mm and 200mm, The strength of the wallettes were not significantly affected by the height/width ratio of the unit. Higher block strength yielded higher wallette stergnth, but only a slight difference in the strength of wallettes built with mortar designation (iii and (iv (i.e. 1:1:6 and 1: 2:9 by volume, cement: lime: sand respectively was obtained. The methods used in the British Standard BS 5628 and the Eurocode EC6 for the determination of the compressive strenght of masonry are reviewd and compared with the test results.

Y.A. Daou

2001-01-01

25

Mechanical properties of a novel PVA hydrogel in shear and unconfined compression.  

Science.gov (United States)

Poly(vinyl alcohol) (PVA) hydrogels have been proposed as promising biomaterials to replace diseased or damaged articular cartilage. A critical barrier to their use as load-bearing tissue replacements is a lack of sufficient mechanical properties. The purpose of this study was to characterize the functional compressive and shear mechanical properties of a novel PVA hydrogel. Two formulations of the biomaterial were tested, one with a lower water content (75% water), and the other with higher water content (80% water). The compressive tangent modulus varied with biomaterial formulation and was found to be statistically strain magnitude and rate dependent. Over a strain range of 10-60%, the compressive modulus increased from approximately 1-18 MPa, which is within the range of the modulus of articular cartilage. The shear tangent modulus (0.1-0.4 MPa) was also found to be strain magnitude dependent and within the range of normal human articular cartilage, but it was not statistically dependent on strain rate, This behavior was attributed to the dominance of fluid flow and related frictional drag on the viscoelastic behavior. Compressive failure of the hydrogels was found to occur between 45 and 60% strain, depending on water content. PMID:11246948

Stammen, J A; Williams, S; Ku, D N; Guldberg, R E

2001-04-01

26

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

27

Compressive strength of continuous fiber unidirectional composites  

Science.gov (United States)

Dow and Rosen's work in 1965 formed an intellectual framework for compressive strength of unidirectional composites. Compressive strength was explained in terms of micro-buckling, in which filaments are beams on an elastic foundation. They made simplifying assumptions, with a two dimensional idealization and linearized material properties. This study builds on their model, recognizing that the shear mode of instability drives unidirectional compressive strength. As a necessary corollary, the predictive methods developed in this study emphasize correct representation of composite shear stiffness. Non-linear effects related to matrix material properties, fiber misalignment, three dimensional representation, and thermal prestrains are taken into account. Four work streams comprise this study: first, development of a closed form analytical model; second, empirical methods development and model validation; third, creation and validation of a unit cell finite element model; and fourth, a patent application that leverages knowledge gained from the first three work streams. The analytical model characterizes the non-linearity of the matrix both with respect to shear and compressive loading. This improvement on existing analyses clearly shows why fiber modulus affects composite shear instability. Accounting for fiber misalignment in the model and experimental characterization of the fiber misalignment continuum are important contributions of this study. A simple method of compressive strength measurement of a small diameter monofilament glass-resin composite is developed. Sample definition and preparation are original, and necessary technologies are easily assessable to other researchers in this field. This study shows that glass fiber composites have the potential for high compressive strength. This potential is reached with excellent fiber alignment and suitable matrix characteristics, and results are consistent with model predictions. The unit cell three dimensional finite element model introduces a boundary condition that only allows compressive and shear deformation, thus recognizing the actual deformation mechanism of a compressed unidirectional composite. A new approach for representing the resin matrix is employed, giving improved correlation to empirical measurements noted in the literature. A method of accounting for realistic composite imperfections is introduced. The patent application work was fed by results from the first three areas. A new engineering structure is created in which buckling is beneficial. Post buckled behavior favorably affects other structural components in an overload situation. The first three work streams form a coherent unit and are mutually supportive. The analytical model predictions are corroborated by the experimental measurements. Finite element model predictions are consistent with the analytical model predictions.

Thompson, Ronald H.

28

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Tan, Ö.; Sahin Zaimoglu, A.

2007-01-01

29

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

30

Short-span compressive strength and interlaminar shear resistance  

Energy Technology Data Exchange (ETDEWEB)

A relatively simple relation between short-span compressive strength and ultimate interlaminar shear strain is derived and shown to fit data for machine-made boards from different sources. Interlaminar shear resistance seems to be the pertinent bond test for edgewise compression strength studies. Experimental results illustrate how (shear) bond strength can be monitored by measuring in-plane modulus and short-span compression strength. Practical aspects of the interlaminar shear resistance test are also discussed.

Amini, J.; Robillard, N. [Domtar Inc., Senneville, Quebec (Canada); Bardeau, C.E. [3M Canada Inc., London, Ontario (Canada)

1995-12-31

31

STRENGTH SHRINKAGE AND CREEP OF CONCRETE IN TENSION AND COMPRESSION  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Kristiawan, S. A.

2006-01-01

32

STRENGTH SHRINKAGE AND CREEP OF CONCRETE IN TENSION AND COMPRESSION  

Directory of Open Access Journals (Sweden)

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

S A Kristiawan

2006-01-01

33

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

34

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 (fmâ??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

35

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2013-01-01

36

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

37

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

38

Calcite-forming bacteria for compressive strength improvement in mortar.  

Science.gov (United States)

Microbiological calcium carbonate precipitation (MCP) has been investigated for its ability to improve the compressive strength of concrete mortar. However, very few studies have been conducted on the use of calcite-forming bacteria (CFB) to improve compressive strength. In this study, we discovered new bacterial genera that are capable of improving the compressive strength of concrete mortar. We isolated 4 CFB from 7 environmental concrete structures. Using sequence analysis of the 16S rRNA genes, the CFB could be partially identified as Sporosarcina soli KNUC401, Bacillus massiliensis KNUC402, Arthrobacter crystallopoietes KNUC403, and Lysinibacillus fusiformis KNUC404. Crystal aggregates were apparent in the bacterial colonies grown on an agar medium. Stereomicroscopy, scanning electron microscopy, and x-ray diffraction analyses illustrated both the crystal growth and the crystalline structure of the CaCO3 crystals. We used the isolates to improve the compressive strength of concrete mortar cubes and found that KNUC403 offered the best improvement in compressive strength. PMID:20467254

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

2010-04-01

39

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

40

The compressive modulus and strength of saturated calcium sulphate dihydrate cements: Implications for testing standards.  

Science.gov (United States)

Calcium sulphate-based bone cement is a bone filler with proven biological advantages including biodegradability, biocompatibility and osteoconductivity. Mechanical properties of such brittle ceramic cements are frequently determined using the testing standard designed for ductile acrylic cements. The aims of the study were (1) to validate the suitability of this common testing protocol using saturated calcium sulphate dihydrate (CSD), and (2) to compare the strength and effective modulus of non-saturated and saturated CSD, in order to determine the changes in the mechanical behavior of CSD upon saturation. Unconfined compression tests to failure were performed on 190 cylindrical CSD samples. The samples were divided into four groups having different saturation levels (saturated, non-saturated) and end conditions (capped and non-capped). Two effective moduli were calculated per sample, based on the deformations measured using the machine platens and a sample-mounted extensometer. The effective moduli of non-saturated groups were found to be independent of the end conditions. The saturated and capped group showed no difference in the effective moduli derived from different measurement methods, while the saturated and non-capped group showed a significant difference between the machine platen- and extensometer-derived moduli. Strength and modulus values were significantly lower for saturated samples. It was assumed that the existence of water in saturated CSD alters the mechanical response of the material due to the changes in chemical and physical behaviors. These factors are considered to play important roles to decrease the shear strength of CSD. It was proposed that the reduction in CSD shear strength evokes local deformation at the platen-sample boundary, affecting the strength and effective moduli derived from the experiments. The results of this study highlighted the importance of appropriate and consistent testing methods when determining the mechanical properties of saturated ceramic cements. PMID:24603215

Koh, Ilsoo; López, Alejandro; Helgason, Benedikt; Ferguson, Stephen J

2014-06-01

 
 
 
 
41

Stability of shear cracks and the calculation of compressive strength  

Energy Technology Data Exchange (ETDEWEB)

Griffith's 1921 theory of crack stability is extended to account for the frictional energy dissipation associated with interfacial sliding when the crack faces are in contact. This global energy balance approach is essentially different from Griffith's 1924 local theory of compression cracks, which assumes that instability occurs when the stress at any point exceeds the intrinsic strength of the material. An explicit expression for critical crack size in compression is obtained. On the basis of this expression we find the most critical crack orientation and define theoretical strength as the critical stress for that orientation. This uniaxial compression strength significantly exceeds the tensile strength. For example, when the coefficient of friction is unity, the ratio of compressive to tensile strength is 8.7, and the crack plane lies at 13/sup 0/ to the loading direction. Following this, the heating due to interfacial sliding is found by a one-dimensional thermoelastic analysis. It is concluded that under normal conditions the stress field acting on the crack faces is only slightly affected by frictional heating, though the temperature rise may be very high, and melting may occur within microseconds.

Dienes, J.K.

1983-02-10

42

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

43

Evaluation of Adhesive and Compressive Strength of Glass Ionomer Cements  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of the study was to assess, compare and evaluate the adhesive strength and compressive strength of different brands of glass ionomer cements to a ceramometal alloy. (A) Glass ionomer cements: GC Fuji II (GC Corporation, Tokyo), Chem Flex (Dentsply DeTrey, Germany), Glass ionomer FX (Shofu-11, Japan), MR dental (MR dental suppliers Pvt Ltd, England). (B) Ceramometal alloy (Ni–Cr: Wiron 99; Bego, Bremen, Germany). (C) Cold cure acrylic resin. (E) Temperature cum humidity control chamb...

2011-01-01

44

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

45

Compressive strength and hydration processes of concrete with recycled aggregates  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-02-15

46

Influence of Different Drying Conditions on High Strength Concrete Compressive Strength  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of different drying conditions on the compressive strength and strength development rates of high strength concrete up to an age of 28 days was evaluated. Two HSC mixes with and without silica fume addition were used to cast cubes of 10 cm size. The cubes were stored in different drying conditions until the age of testing at 3, 7, 28 days.

M. Safan

2001-01-01

47

[Compressive and bend strength of experimental admixed high copper alloys].  

Science.gov (United States)

Mixed alloys for dental amalgams have been used mainly in the form of admixed alloys, where eutectic spheres are blend with conventional flakes. In the present study the compressive strength, bend strength and microstructure of two high-copper alloys (Tytin, Ana-2000) is compared with three experimental alloys prepared of the two high copper by mixing them in proportions of 3:1, 1:1 and 1:3 by weight. The results revealed that experimental alloys inherited high early and final strength values without any significant change in their microstructure. PMID:3153681

Sourai, P; Paximada, H; Lagouvardos, P; Douvitsas, G

1988-01-01

48

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 10"9 and 2 x 10"1"0 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

1989-10-02

49

Prediction of Compressive Strength of Concrete using Artificial Neural Network  

Directory of Open Access Journals (Sweden)

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

Wankhade M W

2013-07-01

50

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

51

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

Nazari, A.; Torgal, Fernando Pacheco

2013-01-01

52

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

53

Bulgarian state standard for determining monoaxial compression strength  

Energy Technology Data Exchange (ETDEWEB)

Discusses Bulgarian, Soviet and ISRM (International Society of Rock Mechanics) standards for determining compression strength of rock samples. The influence of rock sample dimensions and number, roughness of plates of hydraulic presses and their diameter and thickness is considered. Bulgarian state standard 173-63, a compromise between Soviet and ISRM standards, may need revision; dimensions and numbers of samples investigated, applied loading procedure and hydraulic press plate dimension are mentioned. Recommendations for an improved standard are made. 21 refs.

Andreev, G.; Manev, G.

1987-12-01

54

Effect of Loading Rate on the Edgewise Compressive Strength of Corrugated Fiberboard.  

Science.gov (United States)

Research was conducted to determine the effect of loading rate on the edgewise compressive strength of corrugated fiberboard. Results indicated that as the loading rate was increased the edgewise compressive strength, parallel to the flutes, also increase...

R. C. Moody J. W. Koning

1966-01-01

55

INTRA-RING COMPRESSION STRENGTH OF LOW DENSITY HARDWOODS  

Directory of Open Access Journals (Sweden)

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

56

Compressive strength test for cemented waste forms: validation process  

International Nuclear Information System (INIS)

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

2007-10-05

57

Natural minerals mixture for enhancing concrete compressive strength  

Directory of Open Access Journals (Sweden)

Full Text Available The construction material quality is required to be improved in order to enhancing structure stability, optimizing construction cost and quality. The kaolin and bentonite have been mixed in equal quantity and treated by heat for 1 hour under 600 ºC, 800 ºC and 1000 ºC to create new minerals under high temperature condition to introduce an acceptable concrete additive for achieving concrete compressive strength in early age. To study micro properties of additive-cement mixture, X-ray and FESEM experiments have been used. The results indicate that acceptable proportion of unheated kaolin-bentonite is improving the concrete compressive response. But if kaolin-bentonite mixture treated by heat under 800 ºC and in quantity of 12 % has been used in concrete mixed design, then the concrete compressive strength of 7 days shows the best result. The result is due to the development of new minerals under high temperature condition in mineral mixture and also kaolin-bentonite additive change cement past crystal and lead to enhancement of nano structural cement bonding

Abdoullah Namdar

2012-10-01

58

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.

59

Compressive strength and hydrolytic stability of fly ash based geopolymers  

Directory of Open Access Journals (Sweden)

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

Nikoli? Irena

2013-01-01

60

High strain rate compression and tension characterization of high strength (automotive) sheet steels  

International Nuclear Information System (INIS)

Compression and tension split Hopkinson bar techniques are used to characterize high strength automotive sheet steels at strain rates of 500/s and 1000/s. Compression and tension data on two representative steel grades are given. There are differences in the measured compression and tension flow stresses for both the steels. The effect of strain rate and steel strength on these differences is discussed

2004-07-20

 
 
 
 
61

Investigation of Salinity Effect on Compressive Strength of Reinforced Concrete  

Directory of Open Access Journals (Sweden)

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

62

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

Directory of Open Access Journals (Sweden)

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

Sudip Talukdar

2007-12-01

63

Permeability, porosity and compressive strength of self-compacting concrete  

Directory of Open Access Journals (Sweden)

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

64

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

65

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

Directory of Open Access Journals (Sweden)

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

Abdoullah Namdar

2014-02-01

66

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

DEFF Research Database (Denmark)

The development of mechanical properties has been studied in a test program comprising 15 different concrete mixes with 3 different w/c ratios and different additions of superabsorbent polymers (SAP). The degree of hydration is followed for 15 corresponding paste mixes. This paper concerns compressive strength. It shows that results agree well with a model based on the following: 1. Concrete compressive strength is proportional to compressive strength of the paste phase 2. Paste strength depends on gel space ratio, as suggested by Powers 3. The influence of air voids created by SAP on compressive strength can be accounted for in the same way as when taking the air content into account in Bolomeys formula. The implication of the model is that at low w/c ratios (w/c 0.45) and addition of large amounts of SAP, this effect cannot counterbalance the strength reducing effect of increased void volume. In these cases, SAP addition reduces the compressive strength.

Hasholt, Marianne Tange; Jespersen, Morten H. Seneka

2010-01-01

67

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Majeed, Sura A.

2011-01-01

68

Mechanical properties of sedimentary soft rock at high temperature. Part 2. Evaluation of temperature dependency of creep behavior based on unconfined compression test  

International Nuclear Information System (INIS)

The geological disposal is expected to be the most practical measure for isolating high-level radioactive waste (HLW). Since heat is generated due to the collapse of nuclide in HLW, the rock mass around the geological disposal facility will experience high temperatures. Therefore, it is important to understand the effect of high temperature on the rock masses. In this study, under different temperature from 24degC to 95degC, a series of unconfined creep tests was conducted on a mudstone and tuffaceous rock, Ohya stone. The results show that the time to failure of Ohya stone is decreased, while the minimum strain rate is increased for high temperature. However, the relationships between the time to failure and the minimum strain rate are dependent on neither creep stress nor temperature. (author)

2006-09-01

69

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

Directory of Open Access Journals (Sweden)

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

U.J. Alengaram

2008-01-01

70

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

1986-03-01

71

Effect of cure time and sample size on compressive strength of LLW  

International Nuclear Information System (INIS)

One area of interest in the solidification of low-level radioactive waste is the compressive strength. This paper deals with the results of compressive strength tests performed at various cure times on cylinder and cube samples of six simulated wastes expected to be generated at the West Valley Demonstration Project

1986-01-01

72

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.

73

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

1991-12-01

74

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

Directory of Open Access Journals (Sweden)

Full Text Available A study has been undertaken to investigate the strength of stabilized clay-soil reinforced with randomly distributed discrete plastic waste fibers by carrying out unconfined compressive strength and tensile-split strength test. In this study, the clay soil was stabilized with lime and rice husk ash mixtures. The effect of the fiber length and content on the compressive and split tensile strength was investigated. The laboratory investigation results show that inclusion of the plastic waste fiber increased significantly both the unconfined compressive strength and tensile-split strength of the stabilized clay soil. The fiber length plays a significant contribution in increasing the soil strength. To contribute for any significant improvement on compression as well as tensile strength, the fiber length should be in range of 20 mm to 40 mm. Fiber reinforcements also reduced soil brittleness by providing smaller loss of post-peak strength.

A. S. Muntohar

2009-01-01

75

Test study of coal's strength and deformation characteristics under triaxial compression  

Energy Technology Data Exchange (ETDEWEB)

The conventional triaxial compression test of No.3 coal seam of Baodian Colliery was carried out with MTS815 servo-controlled rock mechanical test system and the strength and deformation characteristics were analyzed. The experimental results indicate that under the confining compression, fissures close due to the large quantity of micro fissures, and the modulus increase with it, but presents nonlinear relation. Under general triaxial compression, and triaxial compression strength of coal specimens and confining compression have good linear relation (the case of uniaxial compression excluded), when the confining compression is less than maximum experimental compression, the destroy of coal mine fits the Coulomb criterion, but because of the obvious heterogeneity of coal specimens, there are large quantity of flaws such as random fissures, and the cohesion is low, it is most possible for the random fissures of coal specimens deviate from {theta} = 45{sup o} + {phi}/2. 7 refs., 5 figs.,. 2 tabs.

Yang Yong-jie; Song Yang; Chen Shao-jie [Shandong University of Science and Technology, Qingdao (China). College of Resource and Environment Engineering

2006-07-01

76

The estimation of compressive strength of normal and recycled aggregate concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Estimation of concrete strength is an important issue in ready-mixed concrete industry, especially, in proportioning new mixtures and for the quality assurance of the concrete produced. In this article, on the basis of the existing experimental data of compressive strength of normal and recycled aggregate concrete and equation for compressive strength calculating given in Technical regulation are compared. The accuracies of prediction by experimental data obtained in laboratory as well ...

2011-01-01

77

Performance Assessment of Portland Cement Pervious Pavement. Report 3 of 4: Compressive Strength of Pervious Concrete Pavements.  

Science.gov (United States)

The pervious concrete system and its corresponding strength are as important as its permeability characteristics. The strength of the system not only relies on the compressive strength of the pervious concrete but also on the strength of the soil beneath ...

A. M. Mulligan M. Chopra M. Wanielista

2006-01-01

78

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Muntohar, A. S.

2009-01-01

79

Compressive epitactic layers on single-crystal components for improved mechanical durability and strength  

International Nuclear Information System (INIS)

Compressive epitactic layers grown on single-crystal substrates are shown to substantially improve mechanical durability. In this study, neodymium-substituted gadolinium gallium garnet (GGG) layers are grown on undoped GGG substrates. The layers are found to dramatically improve the abrasion resistance of the substrates, but to have only a slight effect on strength. Abrasion treatments, which cause up to 20 times decrease in the strength of substrates without epitactic layers, do not cause a significant decrease in the strength of substrates with these compressive surface layers. This permits the high strength of specially prepared strong substrates to be retained after abrasion

1987-09-01

80

Multiple Regression Model for Compressive Strength Prediction of High Performance Concrete  

Directory of Open Access Journals (Sweden)

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

M. F.M. Zain

2009-01-01

 
 
 
 
81

Neuromuscular Compression Garments: Effects on Neuromuscular Strength and Recovery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Graduated compression stockings have been used as a mechanical method of deep vein thrombosis prophylaxis for several years. Several studies have demonstrated an increase in mean deep venous velocity, reduced venous pooling, improved venous return, and increase blood lactate clearance in subjects who wore graduated compression stockings during exercise. A possible improvement in venous return during and after exercise may facilitate the clearance of metabolites produced during exercise. Also,...

Bottaro, Martim; Martorelli, Saulo; Vilac?a, Jose?

2011-01-01

82

Fracture Energy of High-Strength Concrete in Compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Compression tests are usually carried out in load control. This implies the termination of the test at the peak point of the load-displacement curve, while the fracture under these conditions becomes unstable at the descending branch of the load displacement relation. However, the descending branch is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical proper...

Dahl, Henrik; Brincker, Rune

1989-01-01

83

Fracture Energy of High-Strength Concrete in Compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Compression tests are usually carried out in load control. This implies the termination of the test at the peak point of the load-displacement curve, while the fracture under these conditions becomes unstable at the descending branch of the load displacement relation. However, the descending branch is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical proper...

Dahl, H.; Brincker, Rune

2005-01-01

84

Fracture Energy of High-Strength Concrete in Compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Compression tests are usually carried out in load control. This implies the termination of the test at the peak point of the load-displacement curve, while the fracture under these conditions becomes unstable at the descending branch of the load displacement relation. However, the descending branch is essential for understanding the fracture mechanism of concrete in compression. In this paper a series of tests is reported, carried out for the purpose of studying the fracture mechanical proper...

Dahl, Henrik; Brincker, Rune

2011-01-01

85

The influence of tensile fatigue damage on residual compressive strength of woven composites  

Energy Technology Data Exchange (ETDEWEB)

The long term mechanical fatigue of a Celion G30-500/PMR-15 woven composite system is investigated to study the interrelationship between thermo-mechanical properties, namely the thermal expansion coefficient (TEC) and the compressive strength. Residual compressive strength measurements (IITRI fixture) conducted on specimens subjected to tension-tension fatigue cycling indicate that this material property is sensitive to cracks and delaminations which form during mechanical cycling. Measured compressive strength degradation are as large as 49% for this material undergoing mechanical fatigue cycling with TEC degradation as large as 61%. Experimental results show that a correlation exists between TEC measurements and compressive strength. This correlation suggests that TEC measurements may be used as a damage evaluation technique.

Mitrovic, M.; Carman, G.P. [Univ. of California, Los Angeles, CA (United States). Mechanical, Aerospace and Nuclear Engineering Dept.

1995-12-31

86

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

Directory of Open Access Journals (Sweden)

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

Djwantoro Hardjito

2004-01-01

87

Functional relation between mineral composition and compression strength of carboniferous rocks from the pilot mine Bogdanka  

Energy Technology Data Exchange (ETDEWEB)

Investigations of dependence of mechanical properties of carboniferous rocks of the Lublin Coal Basin on their mineral composition are discussed. Determining mechanical properties of rocks surrounding coal seams is necessary for optimization of roof control methods and forecasting subsidence, deformations of walls of workings and roof, and floor tendency to swelling. Twenty five rock samples from the Bogdanka mine were tested: sandstones, mudstones, claystones, sideritic claystone, siderites and coal. The following properties were tested: compression strength of rock samples with natural moisture content, compression strength of dried rock samples, compression strength of rock with maximum moisture content, tensile properties and shear properties. Investigations show that compression strength of rock samples with natural moisture content increases with increasing content of quartz and feldspars and decreases with increasing content of coal and and silty minerals. No functional relationship between mechanical properties of sedimentary rocks and proportion of carbonates or siderite can be established. (4 refs.) (In Polish)

Kowalski, W.M.; Motyczka, A.; Stalega, S.; Motyczka, W.

1981-01-01

88

Compressive Strength of Stainless-Steel Sandwiches at Elevated Temperatures  

Science.gov (United States)

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

Mathauser, Eldon E.; Pride, Richard A.

1959-01-01

89

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2004-01-01

90

Face compression yield strength of the copper-Inconel composite specimen  

Energy Technology Data Exchange (ETDEWEB)

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.

Horie, T.

1987-05-01

91

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

1987-01-01

92

Standard test method for edgewise compressive strength of flat sandwich constructions  

Energy Technology Data Exchange (ETDEWEB)

This method covers determination of the compressive properties of flat structural sandwich constructions in a direction parallel to the plane of the sheet of sandwich. Significance of the edgewise compressive strength of flat sandwich constructions, apparatus, dimensions, number and preparation of specimens, conditioning, procedure and reporting are discussed.

1980-01-01

93

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

94

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Tinic, C.; Bru?hwiler, E.

1985-01-01

95

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-29

96

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

97

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 inc...

2012-01-01

98

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

International Nuclear Information System (INIS)

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

1993-02-15

99

Effect of Silica Nanoparticles on Compressive Strength of Leaves-Waste Composite  

Science.gov (United States)

The utilization of solid-waste, especially leaves-waste is one of interesting research of environmental field. One of them is making a composite using polyvinyl acetate (PVAc) polymer as binder (matrix) and silica nanoparticles as reinforcement (filler) to improve the strength of composite-produced. Those raw materials preliminary were mixed by simple mixing with varied compositions and then hot-pressed at 36 MPa and 100 °C for 20 minutes. From compressive strength test, it was found that composite with composition 7:8 of PVAc and leaves-waste had maximum compressive strength, i.e. 57.60 MPa. It was also that the enhancement of strength due to PVAc fraction (w/w) increasing is a percolation behavior, even though its mathematical explanation has not been performed. Into composition of maximum strength above, silica with average size is 74 nm then was added to improve the strength and found that at silica weight fraction of 0.79 (%w/w), the composite had optimum compressive strength, i.e. 70.5 MPa, or increased up to 22.4% of that without silica. The final compressive strength was very comparable to some building goods such as sandstones and bricks. The composite density was also measured and obtained that it was about 0.9 g/cm3 that is very close to some usual woods.

Masturi, Masturi; Aliah, Hasniah; Aji, Mahardika Prasetya; Sagita, Adi Ardian; Bukit, Minsyahril; Sustini, Euis; Khairurrijal, Khairurrijal; Abdullah, Mikrajuddin

2011-12-01

100

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

Directory of Open Access Journals (Sweden)

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

Antonius

2012-11-01

 
 
 
 
101

A new look at the uniaxial compressive strength of coal  

Energy Technology Data Exchange (ETDEWEB)

The US Bureau of Mines has recently completed a comprehensive study of coal strength. More than 3200 individual test results from over 50 seams were extracted from the literature and combined into a data base of the uniaxial comprehensive strength of coal. In addition, more than 100 case studies of in-mine pillar performance were available in the Analysis of Retreat Mining Pillar Stability (ARMPS) data base. Statistical analysis of this data has yielded valuable results. The data show clearly that the `size effect` is related to coal structure. The widely-used Gaddy formula, which predicts a significant strength reduction as the specimen sized is increased, was found to apply only to `blocky` coals. For friable coals, the size effect was much less pronounced or even non-existent. Case histories of failed pillars are the best available data on in situ coal strength. This study found no correlation between the stability factor of failed pillars and coal specimen strength. Pillar design was much more reliable when a uniform coal strength was used in all case histories. 25 refs., 7 figs., 1 tab.

Mark, C.; Barton, T.M. [US Bureau of Mines, Pittsburgh, PA (United States). Pittsburgh Health and Safety Research Center

1996-12-31

102

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

103

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

International Nuclear Information System (INIS)

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

2012-09-01

104

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

105

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

Directory of Open Access Journals (Sweden)

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

Ramadhan W. Salim

2014-06-01

106

The estimation of compressive strength of normal and recycled aggregate concrete  

Directory of Open Access Journals (Sweden)

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

Jankovi? Ksenija

2011-01-01

107

Permeability, porosity and compressive strength of self-compacting concrete  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Most deterioration affecting the durability of self-compacting concrete structures is mediated by water penetration in the concrete, a condition related to its porous structure. The present study analyzes these two factors. To this end, two types of concrete were prepared, a self-compacting and a traditional vibrated concrete, with different W/C ratios and different types of cement. The results of low-pressure water testing to evaluate permeability and analyses to determine compressive streng...

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

2005-01-01

108

A Study on the Compression Strength of Human Vertebrae.  

Science.gov (United States)

The strength of the vertebrae in the age group from 19 to 40 years underwent changes under the rate of loading 10 mm/min, on the average from 400 kg in the cervical region to 1300 kg in the lumbar one. In case of axial loading the sublimbic zone proved to...

S. A. Gozulov V. A. Korzhenyants V. G. Skrupnik Y. N. Sushkov

1972-01-01

109

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

2003-11-27

110

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

Directory of Open Access Journals (Sweden)

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

111

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

Directory of Open Access Journals (Sweden)

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

112

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.

113

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

114

A new approach to compressive strength assessment of concrete: Image processing technique  

Science.gov (United States)

In this study, the compressive strength levels of different concrete classes were estimated using an image processing technique. A series of different concretes were prepared by applying different water/cement ratios. The percentages of cement matrix, aggregate, and air void were calculated by processing the images obtained from the surfaces of hardened concretes. The relation between the parameters that were calculated via image processing and the compressive strengths of the concretes produced were examined. By this means, the compressive strength levels of concretes were estimated one by one via the developed image processing software and ImageJ. It was found that the compressive strength levels of concretes can be estimated with a high level of correlation by using the values obtained via the image processing technique. The developed software can be used to estimate the compressive strength levels of concretes. In addition, in considering concrete age, cure conditions, and relative humidity, the method used in this study can be used together with destructive and non-destructive test methods.

Ba?yi?it, Celalettin; Çomak, Bekir; Kilinçarslan, ?emsettin

2012-09-01

115

Compressive strength measurements in aluminum for shock compression over the stress range of 4-22 GPa  

International Nuclear Information System (INIS)

Measurements of the high-pressure compressive strength are presented for several aluminum alloys shocked to 22 GPa. Five well-characterized aluminum materials were studied, including 6061 alloy with three average grain sizes (50, 30, and yield-YHEL), increases with applied stress and plastic strain. A strength model was developed to describe this increase, which fits the data accurately to 55 GPa and reveals that ?Y increases with shock stress in three distinct regions. It also strongly indicates that metallurgical properties, such as impurities and grain size, influence the ambient yield strength, but not the change in strength, which appears to be controlled by the shock-deformed aluminum matrix and possibly grain boundaries

2005-08-01

116

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

International Nuclear Information System (INIS)

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

2012-03-01

117

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

Directory of Open Access Journals (Sweden)

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

118

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)

2009-10-01

119

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

International Nuclear Information System (INIS)

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

2003-10-01

120

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

International Nuclear Information System (INIS)

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

1994-08-21

 
 
 
 
121

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

Directory of Open Access Journals (Sweden)

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

122

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

1991-01-01

123

Effect of Test Circumstances on Compressive Strength of Porous Calcium Phosphate Ceramics for Establishment of Standard Measurement Condition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In order to establish a reasonable biomimetic condition for compressive strength of bioactive ceramics, the compressive strengths of several commercial bioactive ceramics were measured under various conditions. All specimens except for one of Japanese ceramics, specimen A, showed no significant differences among the conditions, but showed a tendency of decreasing the compressive strength more than 10% in comparison to the dry condition that was conventionally described in product brochures. F...

Masanori Kikuchi

2011-01-01

124

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

Directory of Open Access Journals (Sweden)

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

Krepelka František

2002-03-01

125

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

Directory of Open Access Journals (Sweden)

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

126

Point load test application for estimating compressive strength of concrete structures from small core  

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Full Text Available To estimate a compressive strength from existing concrete structures by core drilling are usually gathered with a diameter specimen of 100mm or three times of maximum coarse aggregate size and examined by uniaxial compressive strength (UCS test as stated in JIS A1170. To get an alternative solution with smaller specimen, point load test (PLT has been selected which is a simple test and widely accepted in rock materials research, but relatively new in concrete. The reliability of PLT is examined by extracting a lot of core drilled specimen from ready mixed concrete blocks with maximum coarse aggregate size, Gmax of 20mm in representative of architectural structures and 40mm in representative of civil structures on the range of concrete grade from 16 to 50. The reference of strength is resulted from concrete core diameter of 100 and 125mm with h/d ratio of 2.0, and examined by UCS test with compressive strength of concrete core of f’cc in results. The core specimen diameters are 35 and 50mm with h/d ratio of 1.5 and 2.0, and examined by PLT with point load index of IS in results. The estimation of compressive strength is conducted by making a linear approximation for IS to f’cc for each group of Gmax and h/d. This study also evaluates the reliability of test results for each core specimen and proposes a new geometric correction factor.

A. Zacoeb

2009-09-01

127

Compressive strength of some polyalkenoates with or without dental amalgam alloy incorporation.  

Science.gov (United States)

The present study compares the compressive strength after one week of some conventional glass-ionomer restorative materials with that of glass ionomers reinforced by the addition of ceramic-coated silver or dental amalgam alloy particles to the aluminosilicate glass powder. Apart from the commercially available Ketac Silver and Miracle Mix, experimental mixtures of Fuji II glass-ionomer powder, the old as well as the new version, with various amounts of either a spherical or lathe-cut amalgam alloy were investigated. For the conventional glass ionomers, the mean compressive strength based on all measurements amounts to 159.9 +/- 4.5 MPa. Both formulations of Fuji II have a comparable strength after one-week maturation. The compressive strength of Ketac Silver does not differ significantly from that of Ketac Fill or from that of the conventional glass ionomers investigated. The effect of admixing amalgam alloy on the compressive strength is found to be determined by the shape and the amount of the alloy particles. Moreover, both parameters are interactive with the formulation of the Fuji glass ionomer used for preparation of the mixture. The results indicate that when dental amalgam alloy is added to the glass ionomer, lathe-cut particles are to be preferred but only in an amount up to 20% by weight. PMID:1813336

Beyls, H M; Verbeeck, R M; Martens, L C; Lemaitre, L

1991-07-01

128

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

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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-methylmethacrylate (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...

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

2010-01-01

129

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Abdul Ahad, Ramzi B.

2000-01-01

130

Strength Behavior Study of Apples under Compression Loading  

Directory of Open Access Journals (Sweden)

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

Abbas Gorji Chakespari

2010-06-01

131

Deflagration explosion of an unconfined fuel vapor cloud  

International Nuclear Information System (INIS)

In the reported study, explosions are produced by injecting a small amount of liquefied petroleum gas (LPG) into air. The ignition and subsequent evolution of the explosion of the unconfined vapor cloud are observed by the simultaneous use of direct photographs and pressure recording. The intensity of the compression waves generated by unconfined combustion are modeled on the basis of the solution of the conservation equations for the flow associated with a spherically symmetric expanding piston. The obtained results are compared with the measurements. It is pointed out that the development of unconfined fuel vapor cloud explosions can be divided into two stages, including a deflagration propagating in premixed gases, which is followed by a diffusion flame promoted by buoyancy and convection. The experimental result from the pressure measurement is found to be quantitatively consistent with the result obtained from the spherical piston model

1979-08-24

132

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

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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

133

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

134

Strength and Permeability of Stabilized Peat Soil  

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

L.S. Wong

2008-01-01

135

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

136

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

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

Akaninyene Afangide Umoh

2012-11-01

137

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

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

138

COMPRESSIVE STRENGTH OF SOLID ROUND STEEL MEMBERS REINFORCED WITH SPLIT PIPE(S  

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Full Text Available Results of experimental investigation on the compressive strength of twenty solid round steel leg member specimens of lattice communication towers reinforced with one or two split pipe(s are presented in this paper. The reinforcement was connected to the leg members either by means of U-bolts only or by means of U-bolts and end welding. It was found that bolt torque has no significant effect in the increase on the strength. It was also concluded that using two split pipes without end welding is better than using one split pipe with end welding. Based on the test results, a simplified and conservative design procedure in accordance to the Canadian and American Standards is proposed to determine the compressive strength of solid round steel leg members reinforced with split pipe(s.

Vrushali M. Tickle

2005-01-01

139

Analyses of spacer grids compression strength and fuel assemblies structural behavior  

International Nuclear Information System (INIS)

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

2013-07-01

140

Behaviour of venous flow rates in intermittent sequential pneumatic compression of the legs using different compression strengths  

International Nuclear Information System (INIS)

A study with 25 patients was performed in order to find out whether intermittent, sequential, pneumatic leg compression is of value in the preventive management of thrombosis due to its effect on the venous flow rates. For this purpose, xenon 133 was injected into one of the foot veins and the flow rate in each case determined for the distance between instep and inguen using different compression strengths, with pressure being exerted on the ankle, calf and thigh. Increased flow rates were already measured at an average pressure value of 34.5 mmHg, while the maximum effect was achieved by exerting a pressure of 92.5 mmHg, which increased the flow rate by 366% as compared to the baseline value. The results point to a significant improvement of the venous flow rates due to intermittent, sequential, pneumatic leg compression and thus provide evidence to prove the value of this method in the prevention of hemostasis and thrombosis. (TRV)

1984-01-01

 
 
 
 
141

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

142

The high temperature compressive strength of non-oxide ceramic foams  

Energy Technology Data Exchange (ETDEWEB)

The compression strengths of five coated vitreous carbon foams under development were measured at 25, 1000, 1200 and 1400 C. Only qualitative trends in the measured strengths were obtainable due to a numerical lack of specimens. One developmental foam was a pyrolytic carbon (PC)-coated reticulated vitreous carbon (RVC) foam, and it was tested in argon at the three elevated temperatures. Four developmental RVC foams had chemical vapor infiltration (CVI)-SiC coatings on them, each with different coating thicknesses and consequential different bulk densities; these SiC-RVC foams were tested in ambient air at the elevated temperatures. The strength of the PC-RVC foam was independent of temperature up to 1400 C in argon. The compressive strengths of the SiC-RVC foams having the two thinnest coatings (or the two smallest bulk densities) were equivalent in ambient air to those of the PC-RVC foam in argon up to 1400 C, while the SiC-RVC foams having the two thickest coatings (or the two greatest bulk densities) were consistently stronger. These results show thin-SiC layered SiC-RVC foams grant oxidation protection that PC-RVC foams do not possess to 1400 C, and that thicker SiC layers on SiC-RVC foams are required for added strength. (orig.)

Wereszczak, A.A. [Oak Ridge National Lab., TN (United States). High Temperature Materials Lab.; Liu, E. [Ultramet, Pacoima, CA (United States); Heng, V. [Ultramet, Pacoima, CA (United States); Kirkland, T.P. [Oak Ridge National Lab., TN (United States). High Temperature Materials Lab.; Ferber, M.K. [Oak Ridge National Lab., TN (United States). High Temperature Materials Lab.

1996-11-30

143

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

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

2007-01-01

144

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

145

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

146

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The aim of this study was to assess the influence of ultrasonic wave propagation on the compressive (CS) and diametral tensile (DTS) strengths of glass ionomer cements (GICs). Three variables were evaluated: conventional GICs, ultrasonic excitation and storage time (1 hour, 24 hours and 7 days). Bov [...] ine teeth molds were used for simulating a clinical ultrasonic excitation. The data were submitted to three-way ANOVA and Tukey tests (P

Terezinha Jesus Esteves, Barata; Eduardo, Bresciani; Akimi, Adachi; Ticiane Cestari, Fagundes; Carlos Augusto Ramos, Carvalho; Maria Fidela Lima, Navarro.

147

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to assess the influence of ultrasonic wave propagation on the compressive (CS) and diametral tensile (DTS) strengths of glass ionomer cements (GICs). Three variables were evaluated: conventional GICs, ultrasonic excitation and storage time (1 hour, 24 hours and 7 days). Bovine teeth molds were used for simulating a clinical ultrasonic excitation. The data were submitted to three-way ANOVA and Tukey tests (P < 0.05). All the tested conventional GICs presented an incre...

Terezinha Jesus Esteves Barata; Eduardo Bresciani; Akimi Adachi; Ticiane Cestari Fagundes; Carlos Augusto Ramos Carvalho; Maria Fidela Lima Navarro

2008-01-01

148

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

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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 i...

Gokhan Gunduz; Suleyman Korkut; Deniz Aydemir; Ilter Bekar

2009-01-01

149

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

Directory of Open Access Journals (Sweden)

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

Suraya Hani Adnan

2012-10-01

150

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

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

Ravindra N. Thakur

2009-06-01

151

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

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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 compressio...

Paulo Ricardo Gherardi Hein; José Tarcísio Lima

2012-01-01

152

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

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

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

2008-01-01

153

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

Energy Technology Data Exchange (ETDEWEB)

Nanoporous metal phosphate (NP-MPO) materials are being developed for removal of contaminant oxyanions (As(OH)O32-, CrO42-, and TcO4-), and cations (mercury, cadmium, and lead) from water and waste streams. Following sequestration, incorporation of metal laden NP-MPOs as a portion of cement formulation would provide an efficient and low-cost way to immobilize metal laden NP-MPOs in an easily handled waste form suitable for permanent disposal. There are no known investigations regarding the incorporation of NP-MPOs in concrete and the effects imparted on the physical and mechanical properties of concrete. Results of this investigation demonstrate: i) incorporation of NP-MPO materials requires additional water in the concrete formulation, which decreases the compressive strength, ii) the high reactive surface area afforded by the fine NP-MPO particles increases the compressive strength, and iii) overall, the compressive strength of concrete waste forms is equal to or greater than standard concrete as a function of the water/cement ratio.

Wellman, Dawn M.; Parker, Kent E.; Mattigod, Shas V.; Fryxell, Glen E.

2008-05-05

154

Investigation of compressive strength of concrete with slag and silica fu  

International Nuclear Information System (INIS)

Without doubt, concrete has special place in construction of different types of structures, and used as one of the most important materials in construction industry. Today, with development and modernization of human knowledge in construction industry, it is possible to reach high performance concrete. Mechanical properties and durability of high performance concrete is quite better than that of conventional concrete. In present, the use of supplementary cementitious materials, mainly silica fume, fly ash and blast furnace slag has become increasingly common for reasons of economy and technical benefits imparted by these materials. The aim of present research is investigation and comparison compressive strength of concrete specimens due to variation of water to cementitious materials ratio (W/C M), silica fume and slag percent and their proportions as cement replacement. Furthermore, it is intended to determine best combination of these materials with cement in concrete (optimum percent) to reach to maximum compressive strength. In the current study, specimens were made in 0.5,0.4 and 0.3 W/C M ratio contained 0,20,35 and 50 percent of slag as cement replacement, where in each slag replacement percent, 0, 5, 10 and 15 percent of of silica fume were used as cement replacement. Results of the current study show that the combination effect of slag and silica fume replacement in concrete leads to the maximum compressive strength in concrete; also there are some optimum percents for replacement of slag and silica fume to cement to get the best results

2002-01-01

155

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

Science.gov (United States)

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

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

2014-03-01

156

Compressive strength of radiation-induced polymer impregnated autoclaved lime-rich clay  

International Nuclear Information System (INIS)

Factors affecting the radiation-induced polymer impregnation of autoclaved lime-rich clay specimens have been investigated. The monomer used is acrylic acid and it was found that the amount of monomer absorbed by the autoclaved specimens increases with increase of acrylic acid concentration and with impregnation time. The degree of polymer incorporation at a fixed ?-irradiation dose of 20 kGy increased with impregnation time of monomer up to 5 hr and also with monomer concentration. An improvement in the compressive strength of the polymer-impregnated autoclaved specimens was observed, and was found to depend mainly on the degree of polymer incorporation. The compressive strength of the autoclaved impregnated specimens was twice the value of the unimpregnated at a degree of polymer incorporation of 12%. The effect of ?-irradiation dose on the degree of polymer incorporation and on the compressive strength of the specimens was also investigated. Infrared and scanning electron microscopic studies of the polymer impregnated specimens were carried out. (author)

1986-01-01

157

A Simplified Failure Criterion for Intact Rocks Based on Rock Type and Uniaxial Compressive Strength  

Science.gov (United States)

The uniaxial compressive strength (UCS) of intact rock, which can be estimated using relatively straightforward and cost-effective techniques, is one of the most practical rock properties used in rock engineering. Thus, constitutive laws to represent the strength and behavior of (intact) rock frequently use it, along with additional intrinsic rock properties. Although triaxial tests can be employed to obtain best-fit failure criterion parameters that provide best strength predictions, they are more expensive and require time-consuming procedures; as a consequence, they are often not readily available at early stages of a project. Based on the analysis of an extensive triaxial test database for intact rocks, we propose a simplified empirical failure criterion in which rock strength at failure is expressed in terms of confining stress and UCS, with a new parameter which can be directly estimated from the UCS for a specified rock type in the absence of triaxial test data. Performance of the proposed failure criterion is then tested for validation against experimental data for eight rock types. The results show that strengths of intact rock estimated by the proposed failure criterion are in good agreement with experimental test data, with small discrepancies between estimated and measurements strengths. Therefore, the proposed criterion can be useful for preliminary (triaxial) strength estimation of intact rocks when triaxial tests data are not available.

Shen, Jiayi; Jimenez, Rafael; Karakus, Murat; Xu, Chaoshui

2014-03-01

158

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

Directory of Open Access Journals (Sweden)

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

Terezinha Jesus Esteves Barata

2008-03-01

159

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

CERN Multimedia

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

American Society for Testing and Materials. Philadelphia

1988-01-01

160

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

 
 
 
 
161

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

162

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

163

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-09-15

164

Factors influencing the strength of cement fly ash base courses  

Energy Technology Data Exchange (ETDEWEB)

Fly ash is a waste produced in coal-fired thermal power stations. It has pozzolonic properties and can therefore be stabilized with either cement or lime to achieve the strength required for use as base courses in pavements. Agencies such as the Electric Power Research Institute (EPRI) have specified criteria and guidelines for the determination of the stabilizer content. This requires carrying out unconfined compression tests on stabilized fly ash specimens prepared and cured as per standard procedures. The stabilizer content is the minimum amount of the stabilizer for which the unconfined compressive strength of the specimens complies with the specified values. The actual curing conditions of the stabilized fly ash bases in the field, however, will differ from those of the laboratory specimens. This will affect the strength development of the bases, their durability, and their performance. The paper explains the details and results of a laboratory experimental program carried out to study the influence of curing conditions and other factors on the development of strength. The program comprised compaction tests and unconfined compression tests. Two Indian fly ashes and a commercial portland cement were used in the study. Six different curing conditions, including controlled and ambient conditions, were adopted. The influence of differences in the dry unit weight and water content was also investigated.

Kaniraj, S.R.; Gayathri, V. [Indian Institute of Technology, New Delhi (India). Dept. of Civil Engineering

2003-10-01

165

Uniaxial compression test series on Bullfrog Tuff  

International Nuclear Information System (INIS)

Nineteen uniaxial compressive experiments were performed on samples of the Bullfrog Member of the Crater Flat Tuff, obtained from drillhole USW-G1 at Yucca Mountain on the Nevada Test Site. The water saturated samples were deformed at a nominal strain rate of 10-5 sec-1, atmospheric pressure and room temperature. Resultant unconfined compressive strengths, axial strains to failure, Young's moduli and Poisson's ratios ranged from 4.63 to 153. MPa, .0028 to .0058, 2.03 to 28.9 GPa and .08 to .16, respectively

1982-01-01

166

Long-term isothermal aging effects on carbon fabric-reinforced PMR-15 composites: Compression strength  

Energy Technology Data Exchange (ETDEWEB)

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 h for the lower temperature runs. The unaged and aged specimens were tested in compression in accordance with Test Method for Compressive Properties of Rigid Plastics (ASTM D 695). Both thin and thick (prism) 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 dependence.

Bowles, K.J.; Roberts, G.D.; Kamvouris, J.E. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center

1997-12-31

167

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.

168

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

169

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

DEFF Research Database (Denmark)

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

Misirlis, K. Newcastle University

2009-01-01

170

The effect of vancomycin addition to the compression strength of antibiotic-loaded bone cements  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this study was to record the effect of the addition of vancomycin on the compression strength of antibiotic-loaded bone cement and to compare the results with the international standards (ISO 5833–2). The formulations tested were: Palamed G and Copal. Vancomycin concentrations of 2.5%, 5% and 10% per powder weight were added. Samples of Palamed G with 5% vancomycin and non-standardised mixing procedures were also tested. The ISO requirements for the testing procedures were fo...

2009-01-01

171

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

Directory of Open Access Journals (Sweden)

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

D.Audinarayana

2013-09-01

172

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

Energy Technology Data Exchange (ETDEWEB)

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.

Biermann, H; Kolbe, A [TU Bergakademie Freiberg, Institute for Materials Engineering, Gustav-Zeuner-Strasse 5, D-09599 Freiberg (Germany); Aneziris, C G; Schaerfl, W [TU Bergakademie Freiberg, Institute for Ceramics, Glass and Construction Materials (Germany); Martin, U; Mueller, A [TU Bergakademie Freiberg, Institute for Materials Science, Gustav-Zeuner-Strasse 5, D-09599 Freiberg (Germany); Herrmann, M, E-mail: biermann@ww.tu-freiberg.d [Fraunhofer IKTS, D-01277 Dresden (Germany)

2010-07-01

173

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

Directory of Open Access Journals (Sweden)

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

Santos Cristina Calmeiro

2013-09-01

174

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Santos, Cristina Calmeiro Dos; Rodrigues, Joa?o Paulo C.

2013-01-01

175

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1992-11-01

176

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

177

Higher compressive strengths and the Bauschinger effect in conformally passivated copper nanopillars  

International Nuclear Information System (INIS)

Our current understanding of size-dependent strength in nano- and microscale crystals is centered around the idea that the overall strength is determined by the stress required to propagate dislocation sources. The nature and type of these dislocation sources is the subject of extensive debate, however, one commonality amongst these theories is that the ability of the free surface to absorb dislocations is a necessary condition for transition to a source controlled regime. In this work we demonstrate that atomic layer deposition (ALD) of conformal 5–25 nm thick TiO2/Al2O3 coatings onto electroplated single crystalline copper pillars with diameters ranging from 75 nm to 1 ?m generally inhibits the ability of a dislocation to vanish at the free surface. Uniaxial compression tests reveal increased strength and hardening relative to uncoated pillars at equivalent diameters, as well as a notable recovery of plastic strain during unloading, i.e. the Bauschinger effect. Unlike previous reports, these coated pillars retained the stochastic signature in their stress–strain curves. We explain these observations within the framework of a size-dependent strength theory based on a single arm source model, dislocation theory, and microstructural analysis by transmission electron microscopy.

2012-05-01

178

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

Science.gov (United States)

Several dental materials have been used for core build-up procedures. Most of these materials were not specifically developed for this purpose, but as a consequence of their properties, have found application in core build-up procedures. Improvements in composites and the development of nanocomposites have led to their use as a core build up material due to their superior mechanical properties, optical properties and ease of handling. However it is not clear if they have better mechanical properties than the conventional core build up materials like amalgam, GIC and dual cure composite core build up material. The strength of the core material is very important and this study was undertaken to compare the mechanical properties of materials used for direct core foundations. The differences between the compressive strength and flexural strength of Filtek Z350 nanocomposite with conventional core build up materials like Amalgam, Vitremer GIC and Fluorocore were tested. Cylindrical plexi glass split molds of dimension 6 ± 1 mm [height] x4 ± 1 mm [diameter] were used to fabricate 15 samples of each core material for testing the compressive strength and rectangular plexi glass split molds of dimension 25 ± 1 mm [length] x 2 ± 1 mm[height] x2 ± 1 mm [width] used for fabricating samples for flexural strength. The samples were stored a water bath at 250 °C for 24 h before testing. The samples were tested using a Universal Instron testing machine. The results of the study showed that Fluorocore had the highest compressive strength and flexural strength followed by Filtek Z350 [nanocomposite] Amalgam had the least flexural strength and Vitremer GIC had the least compressive strength. Thus flurocore and nanocomposite are stronger than other core build up materials and hence should be preferred over other conventional core build up materials in extensively damaged teeth. PMID:24431748

Jayanthi, Narasimha; Vinod, V

2013-09-01

179

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

180

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

Science.gov (United States)

The application of microorganisms in the field of construction material is rapidly increasing worldwide; however, almost all studies that were investigated were bacterial sources with mineral-producing activity and not with organic substances. The difference in the efficiency of using bacteria as an organic agent is that it could improve the durability of cement material. This study aimed to assess the use of biofilm-forming microorganisms as binding agents to increase the compressive strength of cement-sand material. We isolated 13 alkaliphilic biofilmforming bacteria (ABB) from a cement tetrapod block in the West Sea, Korea. Using 16S RNA sequence analysis, the ABB were partially identified as Bacillus algicola KNUC501 and Exiguobacterium marinum KNUC513. KNUC513 was selected for further study following analysis of pH and biofilm formation. Cement-sand mortar cubes containing KNUC513 exhibited greater compressive strength than mineral-forming bacteria (Sporosarcina pasteurii and Arthrobacter crystallopoietes KNUC403). To determine the biofilm effect, Dnase I was used to suppress the biofilm formation of KNUC513. Field emission scanning electron microscopy image revealed the direct involvement of organic-inorganic substance in cement-sand mortar. PMID:22450795

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

2012-03-01

 
 
 
 
181

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.

182

The effects of aging on compressive strength of low-level radioactive waste form samples  

International Nuclear Information System (INIS)

The Field Lysimeter Investigations: Low-Level Waste Data Base Development Program, funded by the US Nuclear Regulatory Commission (NRC), is (a) studying the degradation effects in organic ion-exchange resins caused by radiation, (b) examining the adequacy of test procedures recommended in the Branch Technical Position on Waste Form to meet the requirements of 10 CFR 61 using solidified ion-exchange resins, (c) obtaining performance information on solidified ion-exchange resins in a disposal environment, and (d) determining the condition of liners used to dispose ion-exchange resins. Compressive tests were performed periodically over a 12-year period as part of the Technical Position testing. Results of that compressive testing are presented and discussed. During the study, both portland type I-II cement and Dow vinyl ester-styrene waste form samples were tested. This testing was designed to examine the effects of aging caused by self-irradiation on the compressive strength of the waste forms. Also presented is a brief summary of the results of waste form characterization, which has been conducted in 1986, using tests recommended in the Technical Position on Waste Form. The aging test results are compared to the results of those earlier tests. 14 refs., 52 figs., 5 tabs

1996-01-01

183

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

184

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

1986-01-01

185

Effect of Relative Proportion of Pozzolana on Compressive Strength of Concrete Under Different Curing Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available In this experimental and analytic research, the effect of curing regime on various combinations of silica fume and fly ash was investigated in terms of development of compressive strength. Over 24 mixes were prepared with the water-to-binder ratios of 0.45, 0.35 and 0.25 and with differing percentage of additives used as a combination of 2 or 3 binders. The specimens were subjected to five different curing regimes ranging from continuously water cured to continuously air cured. Results show that it is economical to use a combination of silica fume and fly ash rather than using only silica fume for attaining the same strength level. Poor curing condition adversely affect the strength characteristics of pozzolanic concrete than that of OPC concrete. For silica fume concrete, it is necessary to apply water curing for the initial 7 days to explore pozzolainc activity but it is imperative to cure the fly ash concrete for an extended period to utilize its full potential.

B. Bhattacharjee

2008-02-01

186

Distribution of the X-ray density, compressive and tensile breaking strength in the human femoral shaft  

Energy Technology Data Exchange (ETDEWEB)

105 cross sections of 21 femora (13 male, 8 female) were examined with respect to X-ray density, compressive and tensile breaking strength. On X-ray photographs of each specimen, the density measurements were obtained with photographic equidenses in 4 sites: anterior, medial, posterior and lateral. Then the compressive and tensile breaking strength were determined on 817 standardized samples from the same sites. The results show, that the X-ray density, compressive and tensile breaking strength respectively represent characteristic features of their distributions, and that these three factors are correlated with one another. From these facts it is derived, that the resultant force in the femoral shaft may be within the cross section of femur, and that the functional adaptation of the bone on its mechanical stress is reached by several factors of bone materials at the same time.

Saito, S. (Koeln Univ. (Germany, F.R.))

1983-01-01

187

Distribution of the X-ray density, compressive and tensile breaking strength in the human femoral shaft  

International Nuclear Information System (INIS)

105 cross sections of 21 femora (13 male, 8 female) were examined with respect to X-ray density, compressive and tensile breaking strength. On X-ray photographs of each specimen, the density measurements were obtained with photographic equidenses in 4 sites: anterior, medial, posterior and lateral. Then the compressive and tensile breaking strength were determined on 817 standardized samples from the same sites.The results show, that the X-ray density, compressive and tensile breaking strength respectively represent characteristic features of their distributions, and that these three factors are correlated with one another. From these facts it is derived, that the resultant force in the femoral shaft may be within the cross section of femur, and that the functional adaptation of the bone on its mechanical stress is reached by several factors of bone materials at the same time. (author)

1983-01-01

188

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

Scientific Electronic Library Online (English)

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

Waldemir, Rodrigues; Mariano Martínez, Espinosa; Wagner Luis, Polito.

189

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

190

On the determination of tensile and compressive strengths of unidirectional fiber composites  

Energy Technology Data Exchange (ETDEWEB)

Stress fields in tabbed unidirectional composite coupons and in cross-ply specimens are examined with a goal towards improving the methods for determining the axial strengths of the unidirectional material. Results of parametric studies for evaluation of the influence of tab materials and geometries as well as adhesive properties on the stress peaks in unidirectional tension coupons are presented. Use of ductile (but tough) adhesives, soft tabs, and low taper angles is recommended to reduce failures near tab ends. Data reduction schemes for evaluation of cross-ply test data are critically examined with due consideration to subcritical damages (such as ply cracks) and expected failure modes. Test results from cross-ply and unidirectional tension and compression specimens of carbon and glass-fiber composites are compared. Some recommendations are made based on the results reported. Tests and data correlations for other composites are suggested for selecting a data reduction scheme acceptable to the composites community.

Chatterjee, S.N.; Yen, C.F. [Materials Sciences Corp., Fort Washington, PA (United States); Oplinger, D.W. [Federal Aviation Administration, Atlantic City International Airport, NJ (United States). FAA Technical Center

1997-12-31

191

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

Directory of Open Access Journals (Sweden)

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

Mücteba Uysal

2011-12-01

192

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.

193

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

194

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

Directory of Open Access Journals (Sweden)

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

M. Scafè

2014-07-01

195

Compressive Strength and Water Permeability Performance of Micronised Biomass Silica Concrete  

Directory of Open Access Journals (Sweden)

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

S.H. Adnan

2009-12-01

196

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.

197

Developing a Material Strength Design Value Based on Compression after Impact Damage for the Ares I Composite Interstage  

Science.gov (United States)

The derivation of design values for compression after impact strength for two types of honeycomb sandwich structures are presented. The sandwich structures in this study had an aluminum core and composite laminate facesheets of either 16-ply quasi or 18-ply directional lay-ups. The results show that a simple power law curve fit to the data can be used to create A- and B-basis residual strength curves.

Nettles, A. T.; Jackson, J. R.

2009-01-01

198

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

Directory of Open Access Journals (Sweden)

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

199

Compressive strength and pore structure of high-performance concrete after exposure to high temperature up to 800 C  

Energy Technology Data Exchange (ETDEWEB)

An experimental program was carried out to study the mechanical properties and pore structure of high-performance concrete (HPC) and normal-strength concrete after exposure to high temperature. After the concrete specimens were subjected to a temperature of 800 C, their residual compressive strength was measured. The porosity and pore size distribution of the concrete were investigated by using mercury intrusion porosimetry. Test results show that HPC had higher residual strength, although the strength of HPC degenerated more sharply than the normal-strength concrete after exposure to high temperature. The changes in pore structure could be used to indicate the degradation of mechanical property of HPC subjected to high temperature. A model was developed by optimizing the parameters in the Ryshkewitch model to predict the relationship between porosity and the strength of HPC.

Chan, Y.N.; Luo, X.; Sun, W.

2000-02-01

200

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

Directory of Open Access Journals (Sweden)

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

Borvorn Israngkura Na Ayudhya

2011-10-01

 
 
 
 
201

Numerical investigations on the role of micro-cracks in determining the compressive and tensile strength of rocks  

Science.gov (United States)

Bonded particle models implemented using the Discrete Element Method (DEM [1]) have proven a useful numerical laboratory to investigate the interplay between geological structure and mechanical response of rock specimens [4]. However, it is well-known that such bonded particle models fail to reproduce the ratios of compressive:tensile strength of rocks (typically ranging between 10:1 and 50:1). Since this strength ratio is a critical geotechnical engineering design parameter, it is important to resolve this discrepancy between rock and their DEM analogues. To date, the largest compressive:tensile strength ratio achieved in DEM rock analogue models ranges between 10:1 and 12:1 [3]. In said studies, the compressive:tensile strength ratio was found to depend on the number of particle bonds removed from the specimen prior to testing; a modelling analogy for changing the micro-crack density within the specimen. These results are consistent with the popular conjecture that the compressive and tensile strengths of rock are impacted by the opening (or closure) of micro-cracks oriented parallel (or perpendicular) to the loading direction. The current research consists of a rigorous analysis of the role of micro-cracks in governing the compressive:tensile strength ratio of DEM rock specimens. Micro-cracks are geometrically represented as planar surfaces of variable size and orientation. Spherical particles are packed around each planar micro-crack forming a surface that is flat on scales larger than the particle scale. This geometrical approach permits prescription of the sizes and orientations of micro-cracks, as well as the crack density. A series of cylindrical DEM rock specimens are prepared with varying micro-crack densities and orientations. Specimens with either or both micro-cracks sub-parallel to, or sub-perpendicular to the cylinder axis are consided. Each DEM rock specimen is subjected to both a numerical uniaxial compression test and a numerical direct tension test. From these tests, four macroscopic material properties are measured for each specimen: Young's modulus, Poisson's ratio, uniaxial compressive strength and unixial tensile strength. Fracture mechanisms are also examined. Preliminary results indicate that both micro-crack density and micro-crack orientation significantly impact the macroscopic mechanical properties of DEM rock specimens. Quantitative results will be presented at the meeting. The software employed for these experiments is ESyS-Particle [2], an Open Source DEM simulation package for multi-core PCs or supercomputers.

Weatherley, D.; Ayton, T.

2012-04-01

202

Uniaxial-compression-test series on Tram tuff  

International Nuclear Information System (INIS)

Twenty-five uniaxial compression experiments were performed on samples of the Tram Member of the Center Flat Tuff obtained from drill hole USW-G1 at Yucca Mountain on the Nevada Test Site. The water saturated samples were deformed at nominal strain rates ranging from 10-2 to 10-6 sec-1, atmospheric pressure and room temperature. Resultant unconfined compressive strengths, axial strains to failure, Young's moduli and Poisson's ratios ranged from 14.5 to 69.2 MPa, .0029 to .0052, 5.17 to 22.5 GPa and .09 to .38, respectively

1982-01-01

203

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

204

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

Directory of Open Access Journals (Sweden)

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

205

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

International Nuclear Information System (INIS)

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

2002-10-01

206

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)

2013-01-01

207

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

Directory of Open Access Journals (Sweden)

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

208

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.

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

209

Influence of carbonation on the compressive strength and thermal conductivity of autoclaved aerated concrete masonry units; Zum Einfluss der Carbonatisierung auf die Druckfestigkeit und Waermeleitfaehigkeit von Porenbetonplansteinen  

Energy Technology Data Exchange (ETDEWEB)

Within a limited research project the influence of carbonation on the compressive strength and the thermal conductivity of commercially available autoclaved aerated concrete masonry units were investigated. Therefor samples have been cut out of complete masonry units and stored at different climate conditions. Subsequent the compressive strength and the thermal conductivity were determined and compared with the declared values of the manufacturers.

Stegmaier, Michael [Materialpruefungsanstalt Universitaet Stuttgart (Otto-Graf-Institut), Abteilung Mineralische Baustoffe, Stuttgart (Germany)

2011-10-15

210

Small-strain shear modulus and strength increase of cement-treated clay  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A simple nondestructive technique was used as an alternative method to monitor the hardening of cement-treated clay as a function of time. The principle of this monitoring technique is based on the use of bender elements to measure the small-strain shear modulus (G0) at various time intervals. The strength increase was monitored by conventional unconfined compression testing. Experimental work was carried out on Kaolin clay treated with Portland cement and blast furnace slag cement at differe...

Verastegui Flores, Ramiro; Di Emidio, Gemmina; Impe, William

2010-01-01

211

Effect of impact damage on the compression strength of filamentary-composite hat-stiffened panels  

Science.gov (United States)

An experimental investigation was conducted to evaluate the effect of low-velocity impact damage on the compression strength of filamentary-composite hat-stiffened panels. Twenty-four specimens of three design configurations fabricated from graphite-epoxy and boron-epoxy materials were tested. All three design configurations met the design buckling requirements in the undamaged condition. The impact damage was caused by firing aluminum spheres at the panels to simulate impact on aircraft from runway stones. Panels were damaged by impact in the hat cap or in the skin beneath the hat cap (regions of high axial stiffness) and in the skin between stiffeners (region of low axial stiffness). The panels were relatively insensitive to impact damage in the regions of low axial stiffness but were very sensitive to impact damage in the regions of high axial stiffness. Test results suggest that impact damage may be more dependent on the matrix properties than on the fiber properties of the composite materials considered.

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

1978-01-01

212

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

Directory of Open Access Journals (Sweden)

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

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

2014-07-01

213

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objectives: 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 Methods: Specimen groups of 40 (eight batches of n = 5) cylinders (6.0 ± 0.1 mm height, 4.0 ±0.1 mm diameter) for compressive testing, bars (25.0 ± 0.1 mm...

Fleming, Garry

2012-01-01

214

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

215

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

216

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

217

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

Science.gov (United States)

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.

Diaz-Diaz, Floriberto; de J. Cano-Barrita, Prisciliano F.; Balcom, Bruce J.; Solis-Najera, Sergio E.; Rodriguez, Alfredo O.

2013-01-01

218

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)

2008-04-01

219

An experimental method of measuring the confined compression strength of geomaterials  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Knowledge of the behaviour of geomaterials under confined compression is a pre-requisite for any analysis of their ballistic performance. This study proposes an experimental method of determining the spherical and deviatoric behaviour of these materials under high pressure. Known as the ‘quasi-oedometric compression test’ it consists of compressing a cylindrical specimen tightly enclosed in a thick confinement vessel. The principles of these quasi-oedometric tests are given first, and the...

Forquin, P.; Arias Herna?ndez, A?ngel; Zaera, Ramo?n

2007-01-01

220

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2011-01-01

 
 
 
 
221

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

222

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

223

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The durability of wood is affected by several factors. For this reason, much research has been done on a variety of chemical compounds for impregnating wood, aimed at preserving it while simultaneously improving its properties. Recent studies of the properties of impregnated wood have demonstrated the possibility of substantially improving its mechanical characteristics. Thus, the purpose of this work was to compare the strength to parallel compression of wooden fibers (Eucalyptus grandis), b...

2004-01-01

224

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)

2009-01-01

225

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

Science.gov (United States)

This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.

Li, Wangnan; Cai, Hongneng; Li, Chao

2013-01-01

226

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

Directory of Open Access Journals (Sweden)

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

Solanki P

2000-04-01

227

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 diffe...

Rooyen, Gerrit T.; Du Preez, Rudy; Villiers, Johan; Cromarty, Robert D.

2010-01-01

228

Compression strength of composite suspension push-rods for Formula 1 racing cars  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Advanced composite materials are extensively used in the construction of a contemporary Formula 1 racing car. This paper describes the manufacture and ultimate mechanical performance under compression of composite suspension push-rods that could typically be used in a Grand Prix racing car. An aerofoil-type cross-section was used with different lay-ups of unidirectional and woven cross-ply carbon/epoxy composite. Failure mechanisms including compression and buckling were observed and the ulti...

1997-01-01

229

A research study on the spallation strength of LY12 aluminum under the pre-compression condition  

Science.gov (United States)

To pre-compress the disk-shaped LY12 samples along the radial direction can be done with the aid of overstress assembly by heating or by mechanical clamping, which can also generate the deviatoric stress fields under different states. The spallation signals of these pre-compressed samples are measured by VISAR in the light-gas gun shock experiments. The experimental results show that even under the same impact velocity, the pullback amplitudes of the velocity at the free surface of the samples vary significantly. According to the experimental data, we propose a distinct concept that the material spallation strength is closely related to the deviatoric stress fields in the material. Based on the numerical simulation, we develop a damage constitutive model, which reveals that the deviatoric stress reduces the tensile threshold of the void growth. The numerical investigations also demonstrate that the spallation strength decreases as pre-compression increases. The experimental idea proposed in this paper can also be used to study the spallation process in other structures.

Zhang, ShiWen; Liu, CangLi; Li, QingZhong; Hua, JinSong; Liu, Qiao

2012-03-01

230

Prediction of Compressive Strength of Self compacting Concrete with Flyash and Rice Husk Ash using Adaptive Neuro-fuzzy Inference System  

Directory of Open Access Journals (Sweden)

Full Text Available Self-compacting concrete is an innovative concrete that does not require vibration for placing and compaction. It is able to flow under its own weight, completely filling formwork and achieving full compaction even in congested reinforcement without segregation and bleeding. In the present study self compacting concrete mixes were developed using blend of fly ash and rice husk ash. Fresh properties of theses mixes were tested by using standards recommended by EFNARC (European Federation for Specialist Construction Chemicals and Concrete system. Compressive strength at 28 days was obtained for these mixes. This paper presents development of Adaptive Neuro-fuzzy Inference System (ANFIS model for predicting compressive strength of self compacting concrete using fly ash and rice husk ash. The input parameters used for model are cement, fly ash, rice husk ash and water content. Output parameter is compressive strength at 28 days. The results show that the implemented model is good at predicting compressive strength.

S. S, Pathak

2012-10-01

231

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

232

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)

2013-07-01

233

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

234

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

Directory of Open Access Journals (Sweden)

Full Text Available

ABSTRACT

Uniaxial compressive strength (UCS deals with materials' to ability to withstand axially-directed pushing forces and especially considered to be rock materials' most important mechanical properties. However, the UCS test is an expensive, very time-consuming test to perform in the laboratory and requires high-quality core samples having regular geometry. Empirical equations were thus proposed for predicting UCS as a function of rocks' index properties. Analytical hierarchy process and multiple regression analysis based methodology were used (as opposed to traditional linear regression methods on data-sets obtained from carbonate rocks in NE Turkey. Limestone samples ranging from Devonian to late Cretaceous ages were chosen; travertine-onyx samples were selected from morphological environments considering their surface environmental conditions Test results from experiments carried out on about 250 carbonate rock samples were used in deriving the model. While the hierarchy model focused on determining the most important index properties affecting on UCS, regression analysis established meaningful relationships between UCS and index properties; 0. 85 and 0. 83 positive coefficient correlations between the variables were determined by regression analysis. The methodology provided an appropriate alternative to quantitative estimation of UCS and avoided the need for tedious and time consuming laboratory testing


RESUMEN

La resistencia a la compresión uniaxial (RCU trata con la capacidad de los materiales para soportar fuerzas empujantes dirigidas axialmente y, especialmente, es considerada ser uno de las más importantes propiedades mecánicas de los materiales rocosos. Sin embargo, una prueba de RCU es costosa, lleva mucho tiempo para hacerlo en el laboratorio y requiere muestras de núcleos de alta calidad que tienen una geometría regular.

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

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

Ersoy Hakan

2012-10-01

235

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

236

A summary of the strength and modulus of ice samples from multi-year pressure ridges  

Energy Technology Data Exchange (ETDEWEB)

Over two hundred unconfined compression tests were performed on vertical ice samples obtained from 10 multi-yr pressure ridges in the Beaufort Sea. The tests were performed on a closed-loop electrohydraulic testing machine at two strain rates (10/sup -5/ and 10/sup -3/ s/sup -1/) and two temperatures (-20/sup 0/ and -5/sup 0/C). This paper summarizes the sample preparation and testing techniques used in the investigation and presents data on the compressive strength and initial tangent modulus of the ice.

Cox, G.F.N.; Mellor, M.; Richter, J.A.; Weeks, W.F.

1985-03-01

237

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

Science.gov (United States)

The compression of a double-notched specimen was used to determine the in-plane shear strength (IPSS) of a carbon/carbon composite in the paper. The effects of the notch distance ( L), thickness ( T), and notch width ( W) and supporting jig on the IPSS of the double-notched specimens were investigated numerically and experimentally. The fracture surfaces were examined by a scanning electron microscope. It was found that the IPSS varied with L. Thin specimen yielded low strength. W has little effect on IPSS. The main failure modes include the matrix shear cracking, delamination, fracture and pullout of fibers or fiber bundles. Meanwhile, a supporting jig can provide lateral support and prevent buckling, therefore lead to the failure in a shear mode.

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

2012-01-01

238

Test Fixtures for Determining the CompresSive or Tensile Strength of Various Rings.  

Science.gov (United States)

A test fixture is provided in which the test ring is kept circular at all times. The compressive or tensile force is exerted upon the circumference of the test ring equally and simultaneously by each of seventy-two rigid steel rocker arms. A central axial...

L. R. Newton

1966-01-01

239

Mechanical behavior and dynamic failure of high-strength ultrafine grained tungsten under uniaxial compression  

International Nuclear Information System (INIS)

We have systematically investigated the quasi-static and dynamic mechanical behavior (especially dynamic failure) of ultra-fine grained (UFG) tungsten (W) under uniaxial compression. The starting material is of commercial purity and large grain size. We utilized severe plastic deformation to achieve the ultrafine microstructure characterized by grains and subgrains with sizes of ?500 nm, as identified by transmission electron microscopy. Results of quasi-static compression show that the UFG W behaves in an elastic-nearly perfect plastic manner (i.e., vanishing strain hardening), with its flow stress approaching 2 GPa, close to twice that of conventional coarse grain W. Post-mortem examinations of the quasi-statically loaded samples show no evidence of cracking, in sharp contrast to the behavior of conventional W (where axial cracking is usually observed). Under uniaxial dynamic compression (strain rate ?103 s-1), the true stress-true strain curves of the UFG W exhibit significant flow softening, and the peak stress is ?3 GPa. Furthermore, the strain rate sensitivity of the UFG W is reduced to half the value of the conventional W. Both in situ high-speed photography and post-mortem examinations reveal shear localization and as a consequence, cracking of the UFG W under dynamic uniaxial compression. These observations are consistent with recent observations on other body-centered cubic metals with nanocrystalline or ultrafine microstructures. The experimental results are discussed using existing models for adiabatic shear localization in metals

2006-01-01

240

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

 
 
 
 
241

Spatial variability of the compressive strength of the Toki granite at the Shobasama and Mizunami Construction Site, Japan  

International Nuclear Information System (INIS)

This paper studies the spatial variability of the laboratory results of uniaxial compressive tests on the Toki granite at the Shobasama and Mizunami Construction Site, Japan. Some of the spatial variability observed in the laboratory results can be indirectly attributed to the high fracture frequency of the upper highly fractured rock domain where 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 level of in-situ rock stress (i.e. maximum shear stress) determined by measurement results obtained from the hydro-fracturing method. The correlation between the laboratory results and the level of in-situ stress is explained by the damage due to the release of the stresses the cores undergo during drilling. An attempt to correct the laboratory results for estimating the in-situ intact rock strength based on its correlation with the in-situ stresses was carried out. (author)

2008-03-01

242

Compressive strength and ductility of short concrete columns reinforced by bamboo  

Directory of Open Access Journals (Sweden)

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

Satjapan Leelatanon

2010-08-01

243

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 ...

2013-01-01

244

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Addition of sugar surfactants, sucrose fatty acid esters and alkylpolyglucosides, to calcium phosphate cement designed for bone reconstruction is described. Thanks to their surface activity and through their adsorption at the surface of the calcium phosphate particles, they both induced a strong increase in the porosity (quantified by Image Analysis) and brought a very good workability. Other properties typically studied for these cements are reported, including setting times, compressive str...

2010-01-01

245

Brazilian tensile strength of rocks with different elastic properties in tension and compression  

Energy Technology Data Exchange (ETDEWEB)

The mechanical properties of rocks are usually measured in compression and then it is often assumed that the tensile properties are similar. The author points out that it is well known that rocks are usually weaker in tension and that the Young's modulus and Poisson's ratio may also be different. A method for correcting the error is given if certain of these properties are known. (LTN)

Sundaram, P.N.; Corrales, J.M.

1980-04-01

246

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

Science.gov (United States)

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.

van Rooyen, Gerrit T.; Preez, Rudy du; Villiers, Johan de; Cromarty, Robert

2010-08-01

247

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 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)

2006-06-01

248

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

249

Improvement compressive strength of cementitious composites in different curing media by incorporating ZrO2 nanoparticles  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In the present work, the effect of curing medium on microstructure, physical, mechanical and thermal properties of ZrO2 nanoparticles blended concrete has been investigated. ZrO2 nanoparticles were partially used instead of cement by 0.5, 1.0, 1.5 and 2.0 weight percent. Curing of the specimens was [...] carried out in water and saturated limewater for 7, 28 and 90 days. The results indicate that ZrO2 nanoparticles up to maximum of 2.0% produces cementitious composite with improved compressive strength by curing in saturated limewater. The optimum level of replacement for the specimens cured in water was 1.0 weight percent. ZrO2 nanoparticles can improve the filler effects and also the high activity of fine particles substantially increases the quantity of strengthening gel. Although the limewater reduces the strength of concrete without nanoparticles when compared with the specimens cured in water, curing the specimens in saturated limewater results in more strengthening gel formation around ZrO2 nanoparticles blended concrete causes high strength.

Rafieipour, Mohammad Hossein; Nazari, Ali; Mohandesi, Mohammad Ali; Khalaj, Gholamreza.

250

Microfracturing of coal due to interaction with CO 2 under unconfined conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Laboratory experiments conducted in the past century have shown that exposure of coal to CO2 under unconfined, hydrostatic conditions leads to reversible adsorption and swelling. However, several authors also report irreversible changes in sorption capacity, sample volume, equilibration time and brittle failure strength. Some relate these effects to the formation of microfractures, while others consider “structural rearrangements” in the macromolecular structure of coal to be responsible....

Hol, S.; Spiers, C. J.; Peach, C. J.

2012-01-01

251

Elevated Temperature, Residual Compressive Strength of Impact-Damaged Sandwich Structure Manufactured Out-of-Autoclave  

Science.gov (United States)

Several 1/16th-scale curved sandwich composite panel sections of a 10 m diameter barrel were fabricated to demonstrate the manufacturability of large-scale curved sections using minimum gauge, [+60/-60/0]s, toughened epoxy composite facesheets co-cured with low density (50 kilograms per cubic meters) aluminum honeycomb core. One of these panels was fabricated out of autoclave (OoA) by the vacuum bag oven (VBO) process using Cycom(Registered Trademark) T40-800b/5320-1 prepreg system while another panel with the same lay-up and dimensions was fabricated using the autoclave-cure, toughened epoxy prepreg system Cycom(Registered Trademark) IM7/977-3. The resulting 2.44 m x 2 m curved panels were investigated by non-destructive evaluation (NDE) at NASA Langley Research Center (NASA LaRC) to determine initial fabrication quality and then cut into smaller coupons for elevated temperature wet (ETW) mechanical property characterization. Mechanical property characterization of the sandwich coupons was conducted including edge-wise compression (EWC), and compression-after-impact (CAI) at conditions ranging from 25 C/dry to 150 C/wet. The details and results of this characterization effort are presented in this paper.

Grimsley, Brian W.; Sutter, James K.; Burke, Eric R.; Dixon, Genevieve D.; Gyekenyesi, Thomas G.; Smeltzer, Stanley S.

2012-01-01

252

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2007-01-01

253

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

254

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-05-15

255

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

International Nuclear Information System (INIS)

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

2012-05-01

256

Strain anisotropy and shear strength of shock compressed tantalum from in-situ Laue diffraction  

Science.gov (United States)

Laser driven shock experiments were performed at the Omega facility to study the dynamic yield strength of ~5 ?m thick single crystal tantalum using in-situ Laue diffraction. Tantalum samples were shocked along the [001] direction to peak stresses up to 50 GPa and probed using a 150 ps pulse of bremsstrahlung radiation from an imploding CH capsule x-ray source timed for when the shock was halfway through the sample. The capsule implosion was monitored by a combination of pinhole cameras and DANTE x-ray diode scopes. Diffraction spots for both the undriven and driven regions of the sample were recorded simultaneously on image plate detectors. The strain state of the material was found by combining the strain anisotropy found from the driven diffraction pattern and with simultaneous VISAR measurements.

Wehrenberg, C.; Comley, A. J.; Rudd, R. E.; Terry, M.; Hawreliak, J.; Maddox, B. R.; Prisbrey, S. T.; Park, H.-S.; Remington, B. A.

2014-05-01

257

Method of increasing the phase stability and the compressive yield strength of uranium-1 to 3 wt. % zirconium alloy  

Energy Technology Data Exchange (ETDEWEB)

A uranium-1 to 3 wt. % zirconium alloy characterized by high strength, high ductility and stable microstructure is fabricated by an improved thermal mechanical process. A homogenous ingot of the alloy which has been reduced in thickness of at least 50% in the two-step forging operation, rolled into a plate with a 75% reduction and then heated in vacuum at a temperature of about 750.degree. to 850.degree. C. and then quenched in water is subjected to further thermal-mechanical operation steps to increase the compressive yield strength approximately 30%, stabilize the microstructure, and decrease the variations in mechanical properties throughout the plate is provided. These thermal-mechanical steps are achieved by cold rolling the quenched plate to reduce the thickness thereof about 8 to 12%, aging the cold rolled plate at a first temperature of about 325.degree. to 375.degree. C. for five to six hours and then aging the plate at a higher temperature ranging from 480.degree. to 500.degree. C. for five to six hours prior to cooling the billet to ambient conditions and sizing the billet or plate into articles provides the desired increase in mechanical properties and phase stability throughout the plate.

Anderson, Robert C. (Crossville, TN)

1986-01-01

258

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

259

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

Directory of Open Access Journals (Sweden)

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

Palomo, A.

2007-08-01

260

Effect of the size and the proportion of gas coal and coal-char on the consist-compressive strength of formed coke  

Energy Technology Data Exchange (ETDEWEB)

Using the raw materials gas coal and weakly caking coal-char, a set of formed cokes was prepare by changing the size of gas coal and weakly caking coal-char. The effect of the size of gas coal and coal-char on the compressive strength of formed cokes was studied. The result shows that the compressive strength of formed coke will enhance with the increase of the size of gas coal when the size of weakly caking coal-char is fixed. The compressive strength of formed coke will reach the maximum when the size of gas coal is between 0.5 to 0.9 mm. The compressive strength of formed coke will be decreased sharply with the increase of the size of the weakly caking coal-char when the size of the gas coal is fixed. The majority of the macerals of formed coke consists of isotropic components by optical observation. The effects of size of the gas coal and the char of weakly caking coal on the macerals of formed coke are very weak. 6 refs., 4 figs., 2 tabs.

Ma, M.; Wang, Y.; Zhou, X. [China University of Mining and Technology, Beijing (China)

2007-04-15

 
 
 
 
261

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

Directory of Open Access Journals (Sweden)

Full Text Available

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

 

Asokan Pappu

2010-03-01

262

Determination of the interlaminar tensile strength of a C/C-composite by the diametral compression test at temperatures up to 1800 C  

Energy Technology Data Exchange (ETDEWEB)

For the determination of the interlaminar tensile strength (ILTS) which is the lowest strength that laminated structures exhibit, a testing procedure was developed which avoids the problems of load transfer of the devices normally used today. It is based on the diametral compression test and it can be demonstrated that this test really leads to interlaminar tensile failure inside the material so that reliable strength values are obtained. This procedure was successfully applied to specimens of a carbon fibre reinforced carbon (CFRC) at temperatures up to 1800 C. It is shown that its ILST increases by about a factor of 2 between room temperature and the highest temperature applied. (orig.) 4 refs.

Soltesz, U.; Schaefer, R.; Thielicke, B. [Fraunhofer-Institut fuer Werkstoffmechanik (IWM), Freiburg im Breisgau (Germany)

1999-03-01

263

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

Directory of Open Access Journals (Sweden)

Full Text Available

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

Abbas Gorji Chakespari

2010-06-01

264

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 des [...] te modelo 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 charac [...] teristic 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.

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

265

Uniaxial and triaxial compression test series on Topopah Spring tuff  

International Nuclear Information System (INIS)

Fifteen uniaxial and triaxial compression experiments were performed on samples of the Topopah Spring Member of the Paintbrush Tuff obtained from drill hole USW-G1 at Yucca Mountain on the Nevada Test Site. The water saturated test specimens were deformed at nominal strain rates of 10-2, 10-4, 10-5 and 10-6 s-1; confining pressures of 0.1, 5 and 10 MPa; and room temperature. Resultant unconfined compressive strengths, axial strains to failure, Young's moduli and Poisson's ratios ranged from 44.9 to 176.6 MPa, .0034 to .0057, 22.9 to 40.8 GPa and .15 to .33, respectively

1982-01-01

266

Uniaxial and triaxial compression test series on Calico Hills tuff  

International Nuclear Information System (INIS)

Forty-four uniaxial and triaxial compression experiments were performed on samples of the Tuffaceous beds of Calico Hills obtained from drill hole USW-G1 at Yucca Mountain on the Nevada Test Site. Water saturated and room dry test specimens were deformed at nominal strain rates of 10-3, 10-5 and 10-7 s-1; confining pressures of 0.1, 10 and 20 MPa; and room temperature. Resultant unconfined compressive strengths, axial strains to failure, Young's moduli and Poisson's ratios ranged from 14.2 to 42.0 MPa, 0.0037 to 0.0087, 2.52 to 9.72 GPA and 0.17 to 0.37, respectively

1982-01-01

267

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

268

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.

269

Unconfined versus confined speleogenetic settings: variations of solution porosity.  

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

Klimchouk Alexander

2006-01-01

270

Nematode Locomotion in Unconfined and Confined Fluids  

CERN Document Server

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

Bilbao, Alejandro; Vanapalli, Siva; Blawzdziewicz, Jerzy

2013-01-01

271

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)] 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

272

Fatigue growth analysis of an inclined crack under uniaxial cyclic loading in materials with different yield strengths in tension and compression  

Energy Technology Data Exchange (ETDEWEB)

In the present paper, an improved strain-energy-density criterion presented recently for the commonly used fracture criterion, the minimum strain-energy-density criterion, is extended to the case of cyclic loading to predict mixed-mode fatigue crack growth in materials with different yield strengths in tension and compression. The analysis of the mixed-mode fatigue crack growth process is very complex. For the purpose of more precisely predicting the mixed mode fatigue crack growth process, the authors developed a numerical scheme in which the improved fatigue crack growth criterion is combined with the displacement discontinuity method, a boundary element method. In the fatigue crack growth analysis of an inclined crack under uniaxial cyclic loading, the stress intensity factors for each increment of the crack growth are calculated by means of the displacement discontinuity method. Fatigue growth analysis of an inclined crack under uniaxial cyclic loading in materials with different yield strengths in tension and compression is carried out.

Yan, X.; Lei, W. (Harbin Inst. of Tech. (China))

1994-04-01

273

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

Directory of Open Access Journals (Sweden)

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

Yu Jingyuan

2011-08-01

274

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

275

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

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

Manas Banerjee

2010-11-01

276

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.

Khedmati, Mohammad Reza; Edalat, Pedram.

277

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

International Nuclear Information System (INIS)

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

2013-05-01

278

The effect of plaster (CaSO4 ·1/2H2O) on the compressive strength, self-setting property, and in vitro bioactivity of silicate-based bone cement.  

Science.gov (United States)

Bone cements have been widely used for orthopedic applications. Previous studies have shown that calcium silicon-based bone cements (CSC) were injectable, bioactive, biodegradable, and mechanically strong in the long term, while their short-term compressive strength was low and setting time was too long. On the other hand, plaster (CaSO(4)·1/2H(2)O, POP) sets quickly upon contact with water and has excellent short-term compressive strength. The aim of this study is to prepare CSC/POP composite cements and investigate the effect of POP on the compressive strength, setting time, injectability, degradation, and in vitro bioactivity of the composite cements. The results have shown that POP content plays an important role to modulate the physicochemical property of CSC. The addition of POP into CSC significantly decreased the initial and final setting time and enhanced the short-term compressive strength and degradation rate. The obtained composite cement with 30% POP has been found to possess optimal setting time and short-term compressive strength. In addition, the prepared composite cements still maintain apatite-mineralization ability in simulated body fluids and their ionic extracts have no significant cytotoxicity to L929 cells. The results suggested that the addition of POP into CSC is a viable method to improve their setting properties and short-term compressive strength. The obtained composite cements with the optimized composition of 70% CSC and 30% POP could be potentially used for bone repair application. PMID:23166057

Liu, Wenjuan; Wu, Chengtie; Liu, Weining; Zhai, Wanyin; Chang, Jiang

2013-02-01

279

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-02-01

280

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)

2011-09-28

 
 
 
 
281

Time-dependent compressive strength of rock containing cracks artificially induced by heating; Jinko netsu kiretsu wo yusuru ganseki no asshuku kyodo no jikan izonsei ni kansuru kenkyu  

Energy Technology Data Exchange (ETDEWEB)

The strength and deformation characteristics of the rocks are affected largely by effect of cracks present in the rocks. Therefore, in order to maintain stable the rock constructions for a long term, it is important to understand strength, deformation characteristics and their time dependence concept of the crack. In general, the strength and deformation characteristics of the rocks without containing any crack (intact rocks) are explained by a form of crack distribution such as crack number, density function and so forth created on loading process. And, Kodama et al. described that Kemeny`s microscopic construction model suits well to the time-dependency and the fracture mechanism of these rocks. However, it is not clear if the same description is possible for the rocks with numberless cracks in original random direction. In this paper, using thermally processed samples of cracked rocks, the strength features accompanied with mono axial compression loading rate under dry and wet conditions were elucidated to investigate if the Kemey`s microscopic construction model can be adopted to fracture mechanism of these rocks. 21 refs., 14 figs.

Furuzumi, M.; Abe, M. [Iwate Univ., Iwate (Japan). Faculty of Engineering; Sugimoto, F. [Akita Univ., Akita (Japan). Mining College; Abe, M. [Tohoku Univ., Sendai (Japan). Faculty of Engineering

1997-04-25

282

Ignition and combustion of unconfined liquid fuel on water  

Energy Technology Data Exchange (ETDEWEB)

Burning of unconfined oil layers on water is an area from which techniques could be developed to improve flame weapons or to remove accidental oil spills. A method is presented by which most petroleum-based liquids can be burned to completion when spilled onto water.

Hillstrom, W.W.

1970-11-01

283

Pressure and temperature dependence of shear modulus and yield strength for aluminum, copper, and tungsten under shock compression  

International Nuclear Information System (INIS)

Experimental data for the shear modulus and yield strength of shocked aluminum, copper, and tungsten were systematically analyzed. Comparisons between these data and calculations using the Steinberg-Cochran-Guinan (SCG) constitutive model [D. J. Steinberg, S. G. Cochran, and M. W. Guinan, J. Appl. Phys. 51, 1498 (1980)] indicate that the yield strength has the same dependence on pressure and temperature as the shear modulus for aluminum for shock pressures up to 50 GPa, for copper to 100 GPa, and for tungsten to 200 GPa. Therefore, the assumption of Yp'/Y0=Gp'/G0,YT'/Y0=GT'/G0 is basically acceptable for these materials, and the SCG model can be used to describe the shear modulus and yield strength of the shocked material at high pressure and temperature

2005-07-01

284

The use of coal fly ash in concrete for marine artificial reefs in the southeastern Mediterranean: compressive strength, sessile biota, and chemical composition  

Energy Technology Data Exchange (ETDEWEB)

To examine the possible use of coal fly ash (CFA) in concrete for artificial reefs, blocks containing 0%, 40%, 60% and 80% CFA as a substitute for sand were deployed in the Mediterranean at 18.5-m depth off the coast of Israel during a period of 33 months. Changes in compressive strength, composition, and coverage of sessile biota species, as well as in trace element concentration of the block surface and in sessile biota from four taxonomic groups, were determined as a function of time at sea and block type. Compressive strength clearly increased with time in all types to values well above the minimal strength considered necessary for stability of the blocks at sea. Moreover, the 40% and 60% CFA blocks were 1.5 times stronger than the 0% and 80% ones. Main sessile taxa recorded were filamentous green algae, bryozoa, barnacles, serpulid polychaeta, hydrozoa, and bivalves. Number of species settled and biotic coverage varied among block side and seasonally, but did not differ significantly between block types. The initial heavy metal composition (Hg, Cd, Pb, Cu, Zn, Cr, Mn, Fe, Al) of the block material was directly proportional to the CFA percentage. At the end of the study, Pb had decreased in all types, Cd in the 60% CFA block, and Fe and Al in the 40% and 60% blocks, while Mn had increased in the blocks with 0% and 80% CFA. After 21 months at sea, the only detectable change was a decrease in Pb concentration in all types, indicating that changes may be due to long-term processes. Trace metal levels (Hg, Cd, Zn, Mn, Cu, Fe, and Al) were measured in the sessile biota (hydrozoa, polychaeta, and bivalvia). In most cases, no dependence was found between metal levels and time at sea or CFA content of the blocks. In the hydroid, metal concentration even decreased over time.

Kress, N.; Tom, M.; Spanier, E. [National Institute of Oceanography, Haifa (Israel)

2002-07-01

285

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

286

Capillary effect on watertable fluctuations in unconfined aquifers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Parlange and Brutsaert [1987] derived a modified Boussinesq equation to account for the capillary effect on watertable dynamics in unconfined aquifers. Barry et al. [1996] solved this equation subject to a periodic boundary condition. Their solution shows the significant influence of capillarity on watertable fluctuations, which evolve to finite-amplitude standing waves at the high frequency limit. Here, we propose a new governing equation for the watertable, which considers both horizontal a...

Kong, Jun; Shen, Cheng-ji; Xin, Pei; Song, Zhiyao; Li, Ling; Barry, David Andrew; Jeng, Dong-sheng; Lockington, David Anthony; Parlange, Jean-yves

2013-01-01

287

Barometric fluctuations in wells tapping deep unconfined aquifers.  

Science.gov (United States)

Barometric effects on water levels in unconfined aquifers can be computed by solution of the differential equation governing the flow of gas in the unsaturated zone subject to the appropriate boundary conditions. Solutions to this equation for two sets of boundary conditions were applied to compute water level response in a well tapping the Ogallala Formation near Lubbock, Texas from simultaneous microbarograph records. -from Author

Weeks, E. P.

1979-01-01

288

Effect of nepheline syenite particle size on diametrical compression strength and reliability of extruded ceramic Raschig rings used in packed towers  

Energy Technology Data Exchange (ETDEWEB)

In order to understand the effect of nepheline syenite particle size on physico-chemical properties of ceramic Raschig rings, the fluxing agent was grinded at different milling times. The compositions were prepared by blending the illitic-kaolinitic clay and pre-grinded particles. The rings were shaped by a laboratory extruder and then were sintered at 1200 degree centigrade. The mechanical reliability of sintered specimens was mathematically described by Weibull theory and the effect of pre-grinding of fluxing agent on Weibull modulus was evaluated by measuring the diametrical compression strength. Weibull modulus and strength were the criteria for selecting the suitable particle size range of nepheline syenite. It was found that the pre-grinding of nepheline syenite acts as fairly strong parameter on microstructure of rings. The investigation concludes that reliable rings can be fabricated if the particle size of nepheline syenite is arranged between 53 and 75 {mu}m. This enhancement in reliability is valuable in packed towers. (Author) 17 refs.

Salem, A.; Rostami, N.

2013-05-01

289

Effect of nepheline syenite particle size on diametrical compression strength and reliability of extruded ceramic Raschig rings used in packed towers  

Energy Technology Data Exchange (ETDEWEB)

In order to understand the effect of nepheline syenite particle size on physico-chemical properties of ceramic Raschig rings, the fluxing agent was grinded at different milling times. The compositions were prepared by blending the illitic-kaolinitic clay and pre-grinded particles. The rings were shaped by a laboratory extruder and then were sintered at 1200 degree centigrade. The mechanical reliability of sintered specimens was mathematically described by Weibull theory and the effect of pre-grinding of fluxing agent on Weibull modulus was evaluated by measuring the diametrical compression strength. Weibull modulus and strength were the criteria for selecting the suitable particle size range of nepheline syenite. It was found that the pre-grinding of nepheline syenite acts as fairly strong parameter on microstructure of rings. The investigation concludes that reliable rings can be fabricated if the particle size of nepheline syenite is arranged between 53 and 75 {mu}m. This enhancement in reliability is valuable in packed towers. (Author)

Salem, A.; Rostami, N.

2013-06-01

290

Effect of nepheline syenite particle size on diametrical compression strength and reliability of extruded ceramic Raschig rings used in packed towers  

International Nuclear Information System (INIS)

In order to understand the effect of nepheline syenite particle size on physico-chemical properties of ceramic Raschig rings, the fluxing agent was grinded at different milling times. The compositions were prepared by blending the illitic-kaolinitic clay and pre-grinded particles. The rings were shaped by a laboratory extruder and then were sintered at 1200 degree centigrade. The mechanical reliability of sintered specimens was mathematically described by Weibull theory and the effect of pre-grinding of fluxing agent on Weibull modulus was evaluated by measuring the diametrical compression strength. Weibull modulus and strength were the criteria for selecting the suitable particle size range of nepheline syenite. It was found that the pre-grinding of nepheline syenite acts as fairly strong parameter on microstructure of rings. The investigation concludes that reliable rings can be fabricated if the particle size of nepheline syenite is arranged between 53 and 75 ?m. This enhancement in reliability is valuable in packed towers. (Author)

2013-01-01

291

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

292

Comparing the strength of f.c.c. and b.c.c. sub-micrometer pillars: Compression experiments and dislocation dynamics simulations  

International Nuclear Information System (INIS)

We compare mechanical strength of f.c.c. gold and b.c.c. molybdenum single crystal pillars of sub-micrometer diameter in uniaxial compression tests. Both crystals show an increase of flow stress with decreasing diameter, but the change is more pronounced in Au than in Mo. The ratio between the observed maximum flow stress and the theoretical strength is much larger in Au pillars than in Mo pillars. Dislocation dynamics simulations also reveal different dislocation behavior in these two metals. While in a f.c.c. crystal a dislocation loop nucleated from the surface simply moves on its glide plane and exits the pillar, in a b.c.c. crystal it can generate multiple new dislocations due to the ease of screw dislocations to change slip planes. We postulate that this difference in dislocation behavior is the fundamental reason for the observed difference in the plastic deformation behavior of f.c.c. and b.c.c. pillars

2008-10-15

293

Development of experimental concepts for investigating the strength behavior of fine-grained cohesive soil in the Spacelab/space shuttle zero-g environment  

Science.gov (United States)

Three different sets of tests are proposed for the NASA Spacelab experimental program. The first of tests, designed to measure the true cohesion of several different soils, would be carried out in space through use of a specially prepared direct shear apparatus. As part of this first series of tests, it is recommended that a set of drained unconfined compression tests be performed terrestrially on the same soils as tested in space. A form of the direct tension test is planned to measure the true tensile strength of the same types of soils used in the first series of tests. The direct tension tests could be performed terrestrially. The combined results of the direct shear tests, direct tension tests, and unconfined compression tests can be used to construct approximate failure envelopes for the soils tested in the region of the stress origin. Relationships between true cohesion and true tensile strength can also be investigated. In addition, the role of physio-chemical variables should be studied. The third set of tests involves using a multiaxial cubical or true triaxial test apparatus to investigate the influence of gravity induced fabric anisotropy and stress nonhomogeneities on the stress strain behavior of cohesive soils at low effective stress levels. These tests would involve both in space and terrestrial laboratory testing.

Bonaparte, R.; Mitchell, J. K.

1981-01-01

294

Unconfined heavy-fermion model of the upsilons  

International Nuclear Information System (INIS)

It is considered the possibility that the upsilon peaks are bound states of F and anti F, where F is a heavy spin-1/2 particle with integral charge. The presently known spectroscopy of the upsilons, neglecting spin effects, can readily be reproduced by a simple potential (which, of course, allows also for the existence of unconfined continuum states of F anti F as well). Predictions are made concerning hadronic production of upsilons, widths of the upsilon system, and other experimental signatures which might differentiate the model from the conventional b-quark picture. (author)

1979-09-08

295

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

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.

Machado, José Saporiti.

296

The use of the percentile method for searching empirical relationships between compression strength (UCS), Point Load (Is50) and Schmidt Hammer (RL) Indices  

Science.gov (United States)

Is50 and RL indices are commonly used to indirectly estimate the compression strength of a rocky deposit by in situ and in laboratory devices. The widespread use of Point load and Schmidt hammer tests is due to the simplicity and the speediness of the execution of these tests. Their indices can be related to the UCS by means of the ordinary least square regression analyses. Several researchers suggest to take into account the lithology to build high correlated empirical expressions (R2 >0.8) to draw UCS from Is50 or RL values. Nevertheless, the lower and upper bounds of the UCS ranges of values that can be estimated by means of the two indirect indices are not clearly defined yet. Aydin (2009) stated that the Schmidt hammer test shall be used to assess the compression resistance of rocks characterized by UCS>12-20 MPa. On the other hand, the Point load measures can be performed on weak rocks but upper bound values for UCS are not suggested. In this paper, the empirical relationships between UCS, RL and Is50 are searched by means of the percentile method (Bruno et al. 2013). This method is based on looking for the best regression function, between measured data of UCS and one of the indirect indices, drawn from a subset sample of the couples of measures that are the percentile values. These values are taken from the original dataset of both measures by calculating the cumulative function. No hypothesis on the probability distribution of the sample is needed and the procedure shows to be robust with respect to odd values or outliers. In this study, the carbonate sedimentary rocks are investigated. According to the rock mass classification of Dobereiner and De Freitas (1986), the UCS values for the studied rocks range between 'extremely weak' to 'strong'. For the analyzed data, UCS varies between 1,18-270,70 MPa. Thus, through the percentile method the best empirical relationships UCS-Is50 and UCS-RL are plotted. Relationships between Is50 and RL are drawn, too. Finally, the goodness of the plotted empirical expressions have been checked through couples of measures selected from the original dataset and not used to search for the empirical relationships. References Aydin A. (2009) ISRM Suggested method for determination of the Schmidt hammer rebound hardness: Revised version. Int J Rock Mech Min Sci, 46:627-634. Bruno G., Vessia G., Bobbo L. (2013) Statistical Method for Assessing the Uniaxial Compressive Strength of Carbonate Rock by Schmidt Hammer Tests Performed on Core Samples. Rock Mech Rock Eng., 46:199-206, DOI: 10.1007/s00603-012-0230-5. Dobereiner L. and De Freitas M.H. (1986) Investigation of Weak Sandstones. Engineering Geology Special Publications, 2:199-205, DOI:10.1144/GSL.ENG.1986.002.01.38.

Bruno, Giovanni; Bobbo, Luigi; Vessia, Giovanna

2014-05-01

297

Comparative evaluation of shear compressive bond strength between cross-linked acrylic resin denture base and cross-linked acrylic resin teeth with different modifcations of their ridge lap surfaces.  

Science.gov (United States)

A major problem commonly observed in denture wearer is the detachment of artifcial tooth/teeth from acrylic denture base. The problem was grave when porcelain teeth used along with the then available denture base materials. The bond formed was purely mechanical and hence debonding of teeth from denture base was a frequent occurrence. Inspite of chemical union between acrylic resin teeth and acrylic denture base material, detachment of teeth particularly anterior teeth is a frequent observation. The objective of the study is to study the effect of change in the surface treatment and surface confguration of ridge lap surface of the teeth on retention of cross-linked acrylic teeth on cross-linked acrylic resin denture base. Sixty specimens were tested for the shear compressive bond strength using instron universal testing machine in KN. Statistical analysis is used. The fndings were analyzed using one-way analysis of variance (ANOVA) and 't' test. Slight modifcation in the ridge lap surface of artifcial teeth alters the strength of the shear compressive bond. Sand papering of ridge lap surfaces improves the shear compressive bond then the one without any modifcation. Maximum shear compressive bond strength can be increased by application of monomer. PMID:24685795

Sadar, Leena; Dhume, Swaroop; Maniar, Neena; Prakash Patil, Jeevan; Rane, Prasad; Gandhewar, Mahesh

2013-01-01

298

Unconfined deflagrative explosions without turbulence: experiments and model  

International Nuclear Information System (INIS)

This paper reviews laboratory, balloon and open field experiments which have been performed to study the deflagration regime in free air. In a first part, are considered different models available to estimate deflagrative unconfined explosions effects, without turbulence. Then, a description is given of the known performed tests, which indicate the effective scale of various experiments, their operating conditions and the type of measurements carried out. Results are presented and discussed. The influence on the explosion force of different parameters (fuel concentration gradients, flammable mixture shape and size, ignition energy) is estimated. The overall conclusion of this survey is that flammable mixtures drifting over open field and ignited, will burn with low flame speed and consequently will generate very weak pressure effects

1989-01-01

299

Physical model simulations of seawater intrusion in unconfined aquifer  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this study is to simulate the seawater intrusion into unconfined aquifer near shoreline and to assessthe effectiveness of its controlling methods by using scaled-down physical models. The intrusion controlled methods studiedhere include fresh water injection, saltwater extraction, and subsurface barrier. The results indicate that under natural dynamicequilibrium between the recharge of fresh water and the intrusion well agree with the Ghyben-Herzberg mathematical solution.Fresh water pumping from the aquifer notably move the fresh-salt water interface toward the pumping well, depending on thepumping rates and the head differences (?h between the aquifer recharge and the salt water level. The fresh water injectionmethod is more favorable than the salt water extraction and subsurface barrier method. The fresh water injection rate of about10% of the usage rate can effectively push the interface toward the shoreline, and keeping the pumping well free of salinity.

Tanapol Sriapai

2012-12-01

300

Influence Factor Analysis on Strength of Lime-Fly Ash Loess  

Directory of Open Access Journals (Sweden)

Full Text Available 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 that 90d strength can be considered to calculate the strength of lime-fly ash loess in practice. And the most important factor to influence the 90d strength of lime-fly ash loess is the amount of fly ash and lime, the second is moisture content, and then is the ratio of fly ash to lime (1:K. These achievements are significant to the design and application of lime-fly ash loess in subgrade construction of loess areas.

Yufen Zhang

2013-06-01

 
 
 
 
301

Avaliação da resistência à compressão, resistência à tração e formação de microfissuras em concretos produzidos com diferentes tipos de cimentos, quando aplicado um pré-carregamento de compressão / Evaluation of compressive strength, tensile strength and microcracking formation in concretes produced with different cements, when a preloading of compression is applied  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Muitas empresas construtoras que querem competitividade no mercado buscam soluções para aumentar a velocidade de seus empreendimentos, tal como a redução do tempo de execução da estrutura, redução do tempo de escoramento e execução antecipada das alvenarias, sem respeitar o prazo mínimo de cura do c [...] oncreto. A retirada precoce do escoramento submete a estrutura a uma carga prematura. Os danos causados pela incompleta reação de hidratação e cura do concreto podem desencadear um processo generalizado de formação de microfissuras. O presente estudo avaliou o comportamento de diferentes tipos de concretos produzidos com quatro diferentes tipos de cimentos, quando submetidos a uma carga precoce de compressão, analisando-se suas propriedades mecânicas. A análise incluiu a avaliação da resistência à compressão, resistência à tração e microestrutura interna do concreto, através de microscopia eletrônica de varredura. Os resultados indicaram que há possibilidade de um processo de formação de microfissuras causadas pelo carregamento precoce no concreto e que há tendência de diminuição dos valores de resistência à tração. Entretanto, verificou-se, mediante análise de microscopia, que as microfissuras formadas pelo carregamento precoce tendem a se recuperar se o processo de cura for retomado ou se cessar o pré-carregamento. Abstract in english Many construction companies seeking competitive advantage in the market search for solutions to increase the speed of their projects, such as reducing the structure execution time, cutting shoring time and expediting the construction of masonry walls, disregarding the minimal time limit for curing c [...] oncrete. Early withdrawal of the concrete structure shoring submits it to a premature load. The damage caused by incomplete hydration reaction and curing of the concrete can trigger a widespread process of formation of microcracks. This study examined the behavior of different types of concrete produced with four different types of cements, subjected to an early compressive load, analyzing their mechanical properties. The analysis included an evaluation of the compressive strength, tensile strength and internal microstructure of the concrete, using scanning electron microscopy. The results indicated that there is a possibility of forming microcracks due to preloading on concrete, and that there is a tendency of reaching lower tensile strength values. However, microscopic analysis showed that the microcracks formed by preloading tend to recover if either the curing process is resumed or if early loading stops.

Vieira, Geilma Lima; Molin, Denise Carpena Coitinho Dal.

302

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Comparou-se a Resistência à Compressão (RC) e à Tração Diametral (TD) de um cimento de ionômero de vidro de alta viscosidade [Fuji IX (GC Corporation)] e de dois novos cimentos Brasileiros [Vitro Molar (DFL) e Bioglass R (Biodinamica)], recentemente lançados no mercado, ambos indicados para o Tratam [...] ento Restaurador Atraumático (ART), em diferentes períodos de tempo. Foram confeccionados quinze corpos-de-prova com 6,0 mm de diâmetro x 3,0 mm de altura para o teste de TD e quinze com 6,0 mm de diâmetro e 12,0 mm de altura para o teste de RC, para cada ionômero a ser testado. Os corpos-de-prova foram armazenados em recipientes plásticos, com água deionizada, e mantidos em estufa a 37ºC e 100% de umidade, até a realização dos testes. Cinco corpos-de-prova de cada material foram submetidos aos testes de TD e RC em cada período de tempo: 1-hora, 24-horas e 7-dias, em uma máquina de testes universal (EMIC - DL 500) a uma velocidade de 1,0 mm/min para RC e 0,5mm/min para TD. Os dados obtidos foram submetidos aos testes ANOVA a dois critérios e Tukey (á=0,05). Os valores médios de RC e TD variaram de 42,03 a 155.47 MPa e de 5,54 a 13,72 MPa, respectivamente para os períodos analisados. O Fuji IX e o Vitro Molar não apresentaram diferenças em relação aos testes de RC e TD, exceto para RC no período de 1-hora. O Bioglass R apresentou os menores valores de RC dos cimentos testados. Na TD o Bioglass R não apresentou diferença em relação aos outros cimentos testados no período de 1-hora e não foi diferente do Vitro-Molar nos períodos de 24-horas e 7-dias. Mais estudos são necessários para avaliar outras propriedades mecânicas desses novos cimentos de ionômero de vidro brasileiros, tais como: tenacidade e desgaste, bem como composição química e biocompatibilidade. Abstract in english 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 Atrauma [...] tic 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.

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

303

EXPLORACIÓN CON REDES NEURONALES ARTIFICIALES PARA ESTIMAR LA RESISTENCIA A LA COMPRESIÓN, EN CONCRETOS FIBROREFORZADOS CON ACERO / EXPLORING ARTIFICIAL NEURAL NETWORKS TO ESTIMATE COMPRESSIVE STRENGTH OF STEEL FIBER-REINFORCED CONCRETE  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish RESUMEN En diseño y construcción de estructuras de concreto, la resistencia a la compresión a 28 días de curado es la especificación de control de estabilidad de la obra. La inclusión de fibras como reforzamiento de la matriz cementicia permite una ganancia en sus propiedades, además de obtener un m [...] aterial de alto desempeño. En las normativas, se plantean formulaciones predictivas de la resistencia a la compresión basadas en unos pocos parámetros de composición del concreto, tales como la relación agua/cemento y el contenido de cemento Portland. Por otra parte, también se han planteado métodos de diseños de concreto para definir la ponderación de sus materiales componentes, teniendo como referencia la resistencia a la compresión del concreto simple. Además, las redes neuronales artificiales, como un símil de las neuronas biológicas, han sido utilizadas como herramientas de predicción de la resistencia a la compresión en el concreto, también con referencia al concreto simple, sin reforzamiento con fibras. Los antecedentes en este uso muestran que es interesante desarrollar aplicaciones en los concretos reforzados con fibras. En el presente trabajo se elaboraron redes neuronales artificiales para predecir la resistencia a la compresión en concretos reforzados con fibras de acero. Los resultados de los indicadores de desempeño mostraron que las redes neuronales artificiales elaboradas pueden realizar una aproximación adecuada al valor real de la propiedad mecánica. Abstract in english ABSTRACT By designing and building concrete structures, the compressive strength achieved at 28-day curing typically represents the stability control specification of any work. Furthermore, reinforcing fibers into the cement based matrix has allowed a gain to their properties, as well as a high perf [...] ormance material. Technical literature states predictive formulations of compressive strength of concrete in function of a few composition parameters, such as water/cement ratio and the Portland cement. Also, there are formulations to find the proportion of the raw materials to get a defined compressive strength, specifically non-reinforced ordinary concrete. Besides artificial neural networks as a metaphor of biological neurons have been used as a tool to predict concrete compressive strength. The experience in this application shows an increasing interest to develop applications using fiber-reinforced concrete. In this paper, an artificial neural network has been developed to predict the compressive strength of steel-fiber-reinforced-concrete. The results prove that developed artificial neural networks may perform an adequate approximation to the actual value of the mechanical property.

Luis Octavio, González Salcedo; Aydée Patricia, Guerrero Zúñiga; Silvio, Delvasto Arjona; Adrián Luis, Ernesto Will.

304

The influence of strain rate and sample inhomogeneity on the moduli and strength of welded tuff  

International Nuclear Information System (INIS)

A series of constant strain rate, unconfined compression experiments was performed on saturated welded tuff specimens collected from Busted Butte near Yucca Mountain, Nevada. Twenty specimens were loaded to failure at strain rates ranging from 10-9s-1 to 10-3s-1, under ambient pressure and temperature conditions. The strength of the specimens showed a continuous decrease with decreasing strain rate between 10-9 s-1 and 10-5 s-1. At the highest strain rate, 10-3 s-1, strengths were less than those observed at 10-5 s-1, likely due to hydrofracturing within the specimen at rapid loading rates. Reduction in strength, corresponding to the decrease in strain rate, is explained in terms of stress corrosion cracking. A detailed examination of six specimens tested at a strain rate of 10-9 s-1, using acoustic wave velocities and CT scans, shows a correlation between the nature of the microstructure of the specimens and the observed strengths and elastic moduli

1993-06-27

305

Transient radial flow to a well in an unconfined aquifer  

Energy Technology Data Exchange (ETDEWEB)

The analytic solutions of Boulton (1954) and Neuman (1972) for transient flow to a well in an unconfined aquifer are based on the assumption that the role of the unsaturated zone can be adequately accounted for by restricting attention to the release of water from the zone through which the water table moves. Both researchers mathematically treat this released water as a time-dependent source term. The differences between the models of Boulton and Neuman are that the former neglects vertical components of flow in the aquifer, but allows for an exponential process for the release of water as a function of time, whereas the latter assumes instantaneous release from storage, but accounts for vertical components of flow. Given this set of assumptions, we examine the applicability of these two methods using a general purpose numerical model through a process of verification extension and comparison. The issues addressed include: the role of well-bore storage in masking intermediate-time behavior, combined effects of exponential release as well as vertical flow, logic for vertical averaging of drawdowns, and the sensitivity of system response to the magnitude of specific yield. The issue of how good the assumptions of Boulton and Neuman are in the context of the general theory of unsaturated flow is addressed in part 2 of this two-part series of reports.

Narasimhan, T.N.; Zhu, Ming.

1991-08-01

306

Interface upconing due to a horizontal well in unconfined aquifer  

Energy Technology Data Exchange (ETDEWEB)

A simplified mathematical model is developed to predict the equilibrium location of upconed interface due to a horizontal well in an unconfined coastal aquifer of finite thickness. The model is based on Dupuit assumption and Ghyben-Herzberg approximation with modified boundary conditions along the shoreline deduced from available analytical solutions. For a specified natural flow condition, the amount of fresh-water discharge to the sea as well as the interface profile and length of intrusion can be determined. With the specification of the permissible extent of upconing from the natural interface location at any section, the model provides an estimate of the amount of water that can be withdrawn by a horizontal well, the upconed interface profile, and the additional length of intrusion. The computed interface profile for the natural flow condition is found to be in good agreement with the results of available analytical solutions. Comparison with the laboratory tests for the upconing case indicates that the simplified model provides a reasonable approximation of the interface profile for assessment of water withdrawal from a coastal aquifer at the initial stage of planning.

Gupta, A.D.; Gaikwad, V.P.

1987-07-01

307

Modelling of unconfined aquifer at Kalpakkam Plant site  

International Nuclear Information System (INIS)

The rainwater is the main source of recharge to the shallow unconfined groundwater system at Kalpakkam plant site. Both single layer and double layer models were conceptualized by employing available geohydrological data in the study area. First considering the sandy formation as a single homogeneous unit layer, the model was constructed and calibrated in two stages viz., steady state flow and transient state flow conditions. During the model calibration, field values of hydraulic conductivity Kx=38.8 m|d, Ky=38.8 m|d, Kz=3.88 m|d for sandy formation and Kx=17.11 m|d, Ky=17.11 m|d, Kz=17.11 m|d for weathered rock, were employed. Similarly the values of (Ss) specific storage 0.0381, 0.000313 were assigned for sandy and weathered rock respectively. The April 2006 water table data were taken as the initial head condition. The constant head boundary was assigned along north, east and west direction. The single layer model was run and calibrated for steady state flow and further developed for transient condition by inputting the successive eight months water table data (May 2006 to December 2006). From the actual lithology of the study area, the model was then developed for double layer system of sand and weathered rock. Since, the water table fluctuations were observed the above two layers per some of the bore wells. The hydraulic conductivity and specific storage of the sandy formation were retained and the appropriate aquifer parameters for weathered zone were also suitably included. The results of single and double layer model were compared with respect to regression coefficients and it was observed that applicability of single or double layer modeling depended on the water column fluctuation at a given bore well location. (author)

2008-07-16

308

Ensaio de cravação pneumática de pino para avaliação da resistência à compressão de juntas de assentamento de alvenaria estrutural / Pneumatic pin penetration test to evaluate the compressive strength of mortar bedding on structural masonry  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Ensaios não destrutivos têm sido propostos e usados para avaliação das condições de alvenarias estruturais, para controle de qualidade e propriedades dos materiais in loco. Entretanto, a maioria dos métodos funciona apenas para argamassas com baixa resistência à compressão ([...] as para avaliação qualitativa, além de não serem práticos para uso em campo, demandando muito tempo para a realização das avaliações. Em função disso, um pinador pneumático foi utilizado para avaliar a profundidade de penetração de pinos de aço e correlacioná-la com a resistência à compressão de argamassas em laboratório. O trabalho mostrou que há uma boa correlação entre a profundidade de cravação de pinos e a resistência à compressão das argamassas, além de ser um ensaio prático, rápido e fácil de ser realizado in loco. Abstract in english Nondestructive tests have been proposed and used for the evaluation of structural masonry conditions, quality control, and properties of materials in-situ. However, most of nondestructive methods work only with mortars with low compressive strength ([...] not practical for in-situ use, requiring too much time to perform evaluations. For those reasons, a pneumatic pin penetration test was used to evaluate the penetration depth of a steel probe and correlate it with the compressive strength of mortar in a laboratory. The study has shown a good correlation between the penetration depth of pins and the compressive strength of mortars, besides proving to be a practical test, which is fast and easy to implement in situ.

Alexandre Lima, Oliveira; Pedro Lehmkuhl, Damiani; Igor Fernando Reitz, Ribeiro; Rafael Andrade, Souza; Luciana Maltez Lengler, Calçada.

309

Compressive strength of glass ionomer cements using different specimen dimensions Resistência à compressão de cimentos de ionômero de vidro utilizando-se diferentes tamanhos de corpos-de-prova  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2007-01-01

310

Compressive strength of resin-modified glass ionomer restorative material: effect of P/L ratio and storage time Resistência à compressão de ionômeros de vidro modificados por resina: efeito da relação P/L e tempos de armazenagem  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to evaluate the compressive strength of resin-modified glass ionomer cement Fuji II LC and Vitremer, in powder/liquid ratios of 1:1, 1:2 and 1:3, at three periods (24 hours, 7 and 28 days of storage in distilled water at 37ºC. For each material, P/L ratio and storage time, 5 cylindrical specimens were prepared, with 4mm diameter and 6mm height, in silicon moulds. Specimens were light-cured for 40 seconds at each extremity, removed from the moulds and laterally light-cured (perpendicular to long axis for 40 seconds, protected as recommended by the manufacturers and immersed for the time tested. The specimens were submitted to compressive strength testing in an Instron machine at a crosshead speed of 1.0mm/min until failure. Data were submitted to ANOVA and Tukey's test (5%, and showed that the compressive strength of resin-modified glass ionomer cement was reduced when P/L ratio was reduced and that the storage in water had little influence on compressive strength.O objetivo deste estudo foi avaliar a resistência à compressão dos cimentos de ionômero de vidro modificados por resina Vitremer e Fuji II LC, nas relações pó/líquido 1:1, 1:2 e 1:3, por três períodos de armazenagem (24 horas, 7 e 28 dias em água destilada a 37 ºC. Para cada material, relação pó/líquido e tempo de armazenagem, cinco corpos-de-prova cilíndricos foram preparados com 4 mm de diâmetro por 6 mm de altura, em moldes de silicone. Os corpos-de-prova foram fotoativados por 40 segundos, em cada extremidade, removidos dos moldes, fotoativado lateralmente (perpendicular ao longo eixo por 40 segundos, protegidos conforme as instruções dos fabricantes e imersos pelo tempo de teste. Os corpos-de-prova foram submetidos à compressão em uma Instron, à velocidade de 1,0 mm/min até a falha. Os dados foram submetidos à análise de variância e ao teste de Tukey (5%, e mostraram que a resistência à compressão do cimento de ionômero de vidro modificado por resina foi reduzida quando a relação P/L foi diminuída e a armazenagem em água destilada teve pouca influência na resistência à compressão.

Mônica Aratani

2005-12-01

311

Compressive strength of resin-modified glass ionomer restorative material: effect of P/L ratio and storage time Resistência à compressão de ionômeros de vidro modificados por resina: efeito da relação P/L e tempos de armazenagem  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to evaluate the compressive strength of resin-modified glass ionomer cement Fuji II LC and Vitremer, in powder/liquid ratios of 1:1, 1:2 and 1:3, at three periods (24 hours, 7 and 28 days) of storage in distilled water at 37ºC. For each material, P/L ratio and storage time, 5 cylindrical specimens were prepared, with 4mm diameter and 6mm height, in silicon moulds. Specimens were light-cured for 40 seconds at each extremity, removed from the moulds and laterally ligh...

2005-01-01

312

Post-failure strength of gypsum silica-sand aggregate stemming material  

Energy Technology Data Exchange (ETDEWEB)

Post-failure stress-strain tests were performed on a mixture of gypsum cement and silica-sand aggregate used as stemming material for emplacement holes in underground nuclear testing. The purpose of these tests was to evaluate the remaining strength of the stemming material after it underwent initial failure at confining pressures typical of those found near the working point of the explosion. The failure data can also provide consitutive parameters that can be incorporated into future numerical calculations of the residual stress field of the stemming material. Individual samples were loaded to failure at a single elevated confining pressure. The experiments spanned a range of confining pressures from 10 to 300 MPa. For a set of samples experiencing failure at a given confinging pressure, each sample was subjected to a different amount of strain (up to 15%) subsequent to failure. After this procedure, each sample of failed material was then reloaded to failure again, but without confining pressure. Results indicate that the unconfined post-failure compressive strength of the material decrease as a function of increasing initial post-failure strain under confining pressure. Also, the samples that have experienced more than 15% initial post-failure strain under confining pressure have a complete loss of strength upon reloading without confining pressure. 4 figs., 1 tab.

Kusubov, A.S.; Anderson, G.D.; Dockery, H.A.

1987-10-01

313

Transport and sedimentation in unconfined experimental dilute pyroclastic density currents  

Science.gov (United States)

We present results from experiments conducted in a new facility that permits the study of large, unconfined particle laden density currents that are dynamically similar to natural dilute pyroclastic density currents (PDCs). Experiments were run in a sealed, air-filled tank measuring 8.5 m long by 6.1 m wide by 2.6 m tall. Currents were generated by feeding mixture of heated particles (5 ?m aluminum oxide, 25 ?m talc, 27 ?m walnut shell, 76 ?m glass beads) down a chute at controlled rates to produce dilute, turbulent gravity currents. Comparison of experimental currents with natural PDCs shows good agreement between Froude, densimetric and thermal Richardson, and particle Stokes and settling numbers; experimental currents have lower Reynolds numbers than natural PDCs, but are fully turbulent. Currents were illuminated with 3 orthogonal laser sheets (650, 532, and 450 nm wavelengths) and recorded with an array of HD video cameras and a high speed camera (up to 3000 fps). Deposits were mapped using a grid of sedimentation traps. We observe distinct differences between ambient temperature and warm currents: * warm currents have shorter run out distances, narrow map view distributions of currents and deposits, thicken with distance from the source, and lift off to form coignimbrite plumes; * ambient temperature currents typically travel farther, spread out radially, do not thicken greatly with transport distance, and do not form coignimbrite plumes. Long duration currents (600 s compared to 30-100 s) oscillate laterally with time (e.g. transport to the right, then the left, and back); this oscillation happens prior to any interaction with the tank walls. Isopach maps of the deposits show predictable trends in sedimentation versus distance in response to eruption parameters (eruption rate, duration, temperature, and initial current mass), but all sedimentation curves can be fit with 2nd order polynomials (R2>.9). Proximal sedimentation is similar in comparable warm and ambient temperature currents, but distal sedimentation (beyond the current runout) increases in warm currents reflecting deposition from coignimbrite plumes. We are currently developing analytical models to link the observed transport and sedimentation results.

Ramirez, G.; Andrews, B. J.; Dennen, R. L.

2013-12-01

314

Synthesis of Zinc Oxide Nanoparticles and Their Effect on the Compressive Strength and Setting Time of Self-Compacted Concrete Paste as Cementitious Composites  

Directory of Open Access Journals (Sweden)

Full Text Available In the present study, the mechanical properties of self-compacting concrete were investigated after the addition of different amounts of ZnO nanoparticles. The zinc oxide nanoparticles, with an average particle size of about 30 nm, were synthesized and their properties studied with the help of a scanning electron microscope (SEM and X-ray diffraction. The prepared nanoparticles were partially added to self-compacting concrete at different concentrations (0.05, 0.1, 0.2, 0.5 and 1.0%, and the mechanical (flexural and split tensile strength of the specimens measured after 7, 14, 21 and 28 days, respectively. The present results have shown that the ZnO nanoparticles were able to improve the flexural strength of self-compacting concrete. The increased ZnO content of more than 0.2% could increase the flexural strength, and the maximum flexural and split tensile strength was observed after the addition of 0.5% nanoparticles. Finally, ZnO nanoparticles could improve the pore structure of the self-compacted concrete and shift the distributed pores to harmless and less-harmful pores, while increasing mechanical strength.

Mohammad Reza Arefi

2012-04-01

315

Synthesis of Zinc Oxide Nanoparticles and Their Effect on the Compressive Strength and Setting Time of Self-Compacted Concrete Paste as Cementitious Composites  

Science.gov (United States)

In the present study, the mechanical properties of self-compacting concrete were investigated after the addition of different amounts of ZnO nanoparticles. The zinc oxide nanoparticles, with an average particle size of about 30 nm, were synthesized and their properties studied with the help of a scanning electron microscope (SEM) and X-ray diffraction. The prepared nanoparticles were partially added to self-compacting concrete at different concentrations (0.05, 0.1, 0.2, 0.5 and 1.0%), and the mechanical (flexural and split tensile) strength of the specimens measured after 7, 14, 21 and 28 days, respectively. The present results have shown that the ZnO nanoparticles were able to improve the flexural strength of self-compacting concrete. The increased ZnO content of more than 0.2% could increase the flexural strength, and the maximum flexural and split tensile strength was observed after the addition of 0.5% nanoparticles. Finally, ZnO nanoparticles could improve the pore structure of the self-compacted concrete and shift the distributed pores to harmless and less-harmful pores, while increasing mechanical strength.

Arefi, Mohammad Reza; Rezaei-Zarchi, Saeed

2012-01-01

316

The compression shear test for determination of interlaminar shear strength of fiber reinforced ceramics under various loading conditions; Der Druck-Scherversuch zur Ermittlung der interlaminaren Scherfestigkeit von faserverstaerkten Keramiken bei unterschiedlichen Beanspruchungsbedingungen  

Energy Technology Data Exchange (ETDEWEB)

A new testing method for determination of the interlaminar shear strength of laminated composites is reported, applied to testing asymmetrically notched specimens under axial compressive loads. With this method, essential drawbacks of hitherto applied tests can be avoided which were due to the complex loading conditions or the complicated stress superpositions involved in this type of tests. With the new testing method, relatively homogeneous shear stress distributions free of superposition of critical normal tensile stresses that will lead to interlaminar failure can be induced in the test specimens along the postulated defect sites. The method can likewise be applied for more complicated load cases, as e.g. measurement of the interlaminar shear strength under cyclic or dynamic loads, or at extremely high temperatures, because load application is particularly easy with this method. By using modified compressive shear specimens and load applicating devices, the effects of superimposed normal compressive stresses at high temperatures were analysed and are described. (orig./CB) [Deutsch] Es wird ein neues Pruefverfahren zur Ermittlung der Interlaminaren Scherfestigkeit (ILSF) von laminierten Verbundwerkstoffen vorgestellt, bei dem unsymmetrisch gekerbte Proben unter axialer Druckbelastung getestet werden. Mit dieser Vorgehensweise werden wesentliche Nachteile der bisher am haeufigsten angewendeten Pruefverfahren vermieden, die aus deren komplexer Beanspruchung bzw. aus komplizierten Spannungsueberlagerungen resultieren. Dagegen koennen in den Druck-Scherproben entlang der kuenftigen Versagensflaeche relativ homogene Schubspannungsverteilungen ohne die Ueberlagerung kritischer Normal-Zugspannungen erzielt werden, die zu einem eindeutigen interlaminaren Versagen fuehren. Wegen der einfachen Art der Lasteinleitung ist diese Methode ausserdem auch fuer kompliziertere Beanspruchungen geeignet, wie z.B. zur Messung der ILSF unter zyklischer oder dynamischer Belastung sowie bei extrem hohen Temperaturen. Mit Hilfe modifizierter Druck-Scherproben und Belastungsvorrichtungen wird darueber hinaus der Einfluss ueberlagerter Normal-Druckspannungen im Hochtemperaturbereich untersucht und dargestellt. (orig.)

Thielicke, B.; Soltesz, U. [Fraunhofer-Institut fuer Werkstoffmechanik, Freiburg (Germany)

1997-12-31

317

Pull Off test to evaluate the compressive strength of concrete: an alternative to Brazilian standard techniques / Ensaio de "Pull Off" para avaliar a resistência à compressão do concreto: uma alternativa aos ensaios normalizados no Brasil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Estimar a resistência à compressão do concreto é uma necessidade em muitos trabalhos de inspeção de estruturas de concreto armado. No Brasil, as ferramentas regulamentadas pela ABNT para este fim são a extração de testemunho, a esclerometria e o ultrassom. Nos Estados Unidos e Europa também são regu [...] lamentadas outras técnicas. O objetivo deste trabalho é estudar a viabilidade do uso do ensaio de "Pull Off" como ferramenta de inspeção em concreto e ainda divulgar a possibilidade de emprego de técnicas complementares as normalizadas no Brasil. Os resultados demonstram que o ensaio "Pull Off" apresenta alto índice de correlação (R²>0,93) com o resultado de resistência à compressão medido tanto em corpos de prova cilíndricos como nos prismáticos. A técnica de esclerometria não apresentou correlação satisfatória (R²?0,6) para o caso de corpos de prova cilíndricos e o ultrassom apresentou alta correlação (R²>0,98), mas se comporta diferente com a mudança de forma dos corpos de prova. Abstract in english To estimate the compressive strength of concrete is necessary in many reinforced concrete structures inspection works. In Brazil, the standard tests for this purpose are: Compressive test in drilled cores, rebound hammer test and ultrasonic test. In the United States and Europe are also regulated ot [...] her techniques. The aim of this paper is to analyze the use of Pull Off test as an inspection tool of concrete and also disclose the possibility of use of complementary techniques to the standard ones in Brazil. The results show that the Pull Off test results in high correlation (R²> 0.93) with the compressive strength, measured in cylindrical and prismatic specimens. The rebound hammer test did not show satisfactory correlation (R²?0.6) for the case of cylindrical specimens. The ultrasonic test showed high correlation (R²> 0.98), but behaves differently with the shape changing of the specimens.

E., Pereira; M. H. F. de, Medeiros.

318

Supplement to procedures, analysis, and comparison of groundwater velocity measurement methods for unconfined aquifers  

International Nuclear Information System (INIS)

This report is a supplement to Procedures, Analysis, and Comparison of Groundwater Velocity Measurement Methods for Unconfined Aquifers and provides computer program descriptions, type curves, and calculations for the analysis of field data in determining groundwater velocity in unconfined aquifers. The computer programs analyze bail or slug tests, pumping tests, Geoflo Meter data, and borehole dilution data. Appendix A is a description of the code, instructions for using the code, an example data file, and the calculated results to allow checking the code after installation on the user's computer. Calculations, development of formulas, and correction factors for the various programs are presented in Appendices B through F. Appendix G provides a procedure for calculating transmissivity and specific yield for pumping tests performed in unconfined aquifers

1988-01-01

319

Resistência à compressão do solo-cimento com substituição parcial do cimento Portland por resíduo cerâmico moído Compressive strength of soil-cement with partial replacement of the Portland cement by crushed ceramic waste  

Directory of Open Access Journals (Sweden)

Full Text Available Neste trabalho, apresenta-se o estudo experimental da resistência à compressão do solo-cimento, com substituição parcial do cimento Portland por resíduo cerâmico moído. Para tanto, foram ensaiados 81 espécimenes cilíndricos desse material à compressão, em que parte do cimento foi substituída por material cerâmico moído. Realizou-se uma programação fatorial, na qual três variáveis foram selecionadas para estudo: o teor de material ligante (cimento + resíduo cerâmico, a umidade do solo e o teor de resíduo cerâmico adicionado. É apresentado um estudo estatístico através de análise de variância da massa específica do material e da resistência a compressão. Tal estudo permitiu concluir-se que substituições de 25 e 57% do teor de cimento por material cerâmico podem produzir blocos de solo-cimento com resistências superiores a 2 MPa, com teor de material ligante de 6 e 8%, respectivamente.In this paper, an experimental study of the compressive strength of soil-cement with partial replacement of the Portland cement by crushed ceramic waste is presented and discussed. For this, eighty-one cylindrical specimens of soil-cement were tested, where part of cement percentage was replaced by crushed ceramic waste. The experiment was conducted in factorial design and three variables were selected and studied: the binding material content (cement + ceramic waste, soil moisture content and the ratio of ceramic waste. A statistical study using variance analysis of the specific mass and compressive strength of the material is presented. This study concluded that replacement ratios of 25 and 57% of the Portland cement by crushed ceramic material can be used to fabricate soil-cement bricks with strength higher than 2 MPa, for a binding material content of 6 and 8% respectively.

Rivanildo Dallacort

2002-12-01

320

Consolidation, permeability, and strength of crushed salt/bentonite mixtures with application to the WIPP [Waste Isolation Pilot Plant  

International Nuclear Information System (INIS)

Three tests were performed to measure the consolidation, permeability, and compressive strength of specimens prepared from bentonite/crushed salt mixtures. Each mixture comprised 30% bentonite and 70% crushed salt based on total dry weight. Brine was added to each mixture to adjust its water content to either 5 or 10% (nominal) of the total dry weight of the mixture. In the consolidation tests, each specimen was subjected to multiple stages of successively higher hydrostatic stress (pressure). During each stage, the pressure was maintained at a constant level and volumetric strain data were continuously logged. By using multiple stages, consolidation data were obtained at several pressures and the time required to consolidate the specimens to full saturation was reduced. Once full saturation was achieved, each specimen was subjected to a final test stage in which the hydrostatic stress was reduced and a permeability test performed. Permeability was measured using the steady flow of brine and was found to range between 1 x 10-17 and 5 x 10-17 m2. After the final test stage, unconfined compressive strength was determined for each specimen and was found to range between 0.5 and 8.1 MPa. Two constitutive models were fitted to the consolidation data. One relatively simple model related volumetric strain to time while the other related instantaneous density to time, pressure, and initial density. 8 refs., 9 figs., 8 tabs

1991-01-01

 
 
 
 
321

Confining model with composite left-handed and unconfined right-handed particles  

International Nuclear Information System (INIS)

We present a fermionic composite model in which left-handed quarks and leptons transform as bound states of three elementary fermions confined under a subcolor gauge group whereas their right-handed partners are unconfined singlets. All the elementary fermions, confined or unconfined, are classified into a single spinor representation. A mass-mechanism, originating from the breaking of the spinor representation, gives masses to the quarks and leptons, originally massless from the anomaly conditions. A natural mechanism arises for the neutrino mass matrix. (orig.)

1982-11-11

322

Dissolution rates and vadose zone drainage from strontium isotope measurements of groundwater in the Pasco Basin, WA unconfined aquifer  

Energy Technology Data Exchange (ETDEWEB)

Strontium isotope compositions measured in groundwater samples from 273 wells in the Pasco Basin unconfined aquifer below the Hanford Site show large and systematic variations that provide constraints on groundwater recharge, weathering rates of the aquifer host rocks, communication between unconfined and deeper confined aquifers, and vadose zone-groundwater interaction. This article describes the evaluation of strontium geochemistry of a major aquifer.

Singleton, Michael J.; Maher, Katharine; DePaolo, Donald J.; Conrad, Mark E.; Dresel, P. EVAN

2006-04-30

323

Dissolution rates and vadose zone drainage from strontium isotope measurements of groundwater in the Pasco Basin, WA unconfined aquifer  

International Nuclear Information System (INIS)

Strontium isotope compositions measured in groundwater samples from 273 wells in the Pasco Basin unconfined aquifer below the Hanford Site show large and systematic variations that provide constraints on groundwater recharge, weathering rates of the aquifer host rocks, communication between unconfined and deeper confined aquifers, and vadose zone-groundwater interaction. This article describes the evaluation of strontium geochemistry of a major aquifer

2006-04-30

324

Data Compression.  

Science.gov (United States)

Introduces this issue, which contains papers from the 1991 Data Compression Conference, and defines data compression. The two primary functions of data compression are described, i.e., storage and communications; types of data using compression technology are discussed; compression methods are explained; and current areas of research are…

Bookstein, Abraham; Storer, James A.

1992-01-01

325

CORRELATION DEVELOPMENT BETWEEN INDENTATION PARAMETERS AND UNAXIAL COMPRESSIVE STRENGTH FOR COLOMBIAN SANDSTONES Desarrollo de Correlaciones entre parámetros de indentación y resistencia comprensiva uniaxial para areniscas colombianas  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Anew way to characterize the perforated formation strength has been implemented using the Indentation test. This test can be performed on irregular cuttings mounted in acrylic resins forming a disc. The test consists of applying load on each sample by means of a flat end indenter. A graph of the load applied VS penetration of the indenter is developed, and the modules of the test, denominated Indentation Modulus (IM) and Critical Transition Force (CTF) are obtained (Ringstad et al., 1998). Ba...

Jefferson Mateus; NestorFernando Saavedra2; Zuly Calderón Carrillo3; Darwin Mateus4

2007-01-01

326

Raman spectroscopic determination of the length, strength, compressibility, Debye temperature, elasticity, and force constant of the C-C bond in graphene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

From the perspective of bond relaxation and vibration, we have reconciled the Raman shifts of graphene under the stimuli of the number-of-layer, uni-axial-strain, pressure, and temperature in terms of the response of the length and strength of the representative bond of the entire specimen to the applied stimuli. Theoretical unification of the measurements clarifies that: (i) the opposite trends of Raman shifts due to number-of-layer reduction indicate that the G-peak shift ...

Yang, X. X.; Li, J. W.; Zhou, Z. F.; Wang, Y.; Yang, L. W.; Zheng, W. T.; Sun, Chang Q.

2011-01-01

327

An evaluation of aquifer intercommunication between the unconfined and Rattlesnake Ridge aquifers on the Hanford Site  

Energy Technology Data Exchange (ETDEWEB)

During 1986, Pacific Northwest Laboratory conducted a study of a portion of the Rattlesnake Ridge aquifer (confined aquifer) that lies beneath the B Pond - Gable Mountain Pond area of the Hanford Site. The purpose was to determine the extent of intercommunication between the unconfined aquifer and the uppermost regionally extensive confined aquifer, referred to as the Rattlesnake Ridge aquifer. Hydraulic head data and chemical data were collected from the ground water in the study area during December 1986. The hydraulic head data were used to determine the effects caused by water discharged to the ground from B Pond on both the water table of the unconfined aquifer and the potentiometric surface of the confined aquifer. The chemical data were collected to determine the extent of chemical constituents migrating from the unconfined aquifer to the confined aquifer. Analysis of chemical constituents in the Rattlesnake Ridge aquifer demonstrated that communication between the unconfined and confined aquifers had occurred. However, the levels of contaminants found in the Rattlesnake Ridge aquifer during this study were below the DOE Derived Concentration Guides.

Jensen, E.J.

1987-10-01

328

Efecto del envejecimiento artificial acelerado sobre la resistencia a compresión de resinas compuestas / Effect of artificial accelerated aging on compression strength of composite resin  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish Este estudio tuvo como objetivo analizar el efecto del envejecimiento artificial acelerado (EAA) sobre la resistencia a compresión de las resinas compuestas Filtek Z-250 (F), Charisma (C), Durafil VS (D), Supreme para cuerpo (SNc) e Supreme translúcido (SNt). Fueron confeccionados 16 especímenes con [...] cada resina compuesta con dimensiones de 4x8mm. Las resinas fueron inseridas en tres incrementos y sobre el último incremento fue colocada una matriz de poliéster y una lamina de vidrio con la finalidad obtener una superficie regular. Cada incremento fue polimerizado con una intensidad de luz entre 580 y 600 mW/cm², la cual era monitoreada con un radiómetro (Gnatus) durante todo el tiempo de utilización. Veinticuatro horas después de la obtención de las muestras, 8 muestras de cada material fueron sometidas a los ensayos de compresión (grupo control) los cuales fueron realizados en una maquina EMIC DL 2000, con una célula de carga de 2000Kgf y velocidad de 0,5mm/min. Las otras 8 muestras de cada material fueron colocados en la máquina de EAA, las cuales permanecieron durante 196 horas, las mismas que equivalen a 5 años de envejecimiento y enseguida sometidos a los ensayos de compresión. Los resultados, fueron sometidos al ANOVA y test de Tukey (p24h. Se pudo concluir que el envejecimiento artificial acelerado aumento la resistencia a compresión de las resinas F, C e SNc. Abstract in english The aim of this study was to analyze the effect of artificially accelerated aging (AAA) on the resistance to compression of resin composites Filtek Z-250 (F), Charisma (C), Durafill VS (D), Supreme for body (SNC) and Supreme Translucent (SNt). Sixteen test specimens measuring 4 x 8 mm were made of e [...] ach resin composite. The resins were inserted in three increments, and on the last of them, a polyester strip and glass slide were placed for the purpose of obtaining a regular surface. Each increment was polymerized by light intensity of 580 to 600 mw/cm², which was monitored with a radiometer (Gnatus) throughout the time of use. Twenty-four hours after the samples were obtained, 8 specimens of each material were submitted to the compression test (Control Group) performed with an EMIC DL 2000, machine, with a 2000 Kgf load cell at a speed of 0.5 mm/min. The other 8 samples of each material were placed in an AAA machine, and remained there for 196 hours, equivalent to 5 years of aging. Next they were submitted to the compression test. The values were submitted to ANOVA and the Tukey test (p24h. It was concluded that artificially accelerated aging increased the resistance to compression of the resin composites F, C and SNc.

Priscila, Nogueira Gomes; José Carlos, Rabelo Ribeiro; Marcos, Ribeiro Moysés; Andréa, Candido Dias; Sérgio, Candido Dias.

329

Evaluación in vitro de la resistencia compresiva de un sellante resinoso fluorado pre y post liberación de flúor / In vitro compressive strength of fluoride-containing resin-based sealant before and after fluoride release  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish Objetivo: Evaluar in vitro la resistencia compresiva de un sellante resinoso fluorado (F) pre y post liberación de flúor luego de la inmersión en agua. Método: Se utilizaron 40 probetas de 6 mm de alto y 20 mm de diámetro de sellante resinoso fluorado (FluroShield, Brasil, Dentsply) y de sellante no [...] fluorado (Concise(TM) Light Cured White Sealant, USA, 3M ESPE). Las probetas fueron divididas en cuatro grupos, dos de sellante resinoso fluorado (F1 y F2) y dos de control (C1 y C2). Un grupo de probetas de sellante fluorado y un grupo del control (F1/C1) se mantuvieron sin exposición al agua, mientras que los grupos restantes (F2/C2) fueron inmersos en agua destilada por 30 días. Se midió la liberación de flúor desde el grupo F2 mediante el método de electrodo selectivo los días 1, 2, 3 y 30. Posteriormente se midió la resistencia compresiva mediante una máquina de ensayos mecánicos universales (Lloyd, LR 100, UK) con una velocidad de cruceta de 1 mm/min. Las comparaciones entre los grupos F1 vs F2 y C1 vs C2 se analizaron con t-Student. El nivel de significancia se estableció a 0.05. Resultados: La resistencia compresiva en MPa antes y después de la inmersión en agua para el sellante resinoso fluorado fue 337.2 y 337.4, mientras que la del sellante control fue 203.8 y 213.4. Para ambos grupos las diferencias observadas no fueron significativas. Se observó un patrón de liberación de flúor inicial de 1.9 ppm durante las primeras 24 horas para luego decaer a 0.0 ppm al tercer día de liberación. Conclusión: La liberación de flúor desde un sellante resinoso fluorado no afectó su resistencia compresiva en este estudio in vitro. Abstract in english Aim: To evaluate in vitro compressive strength of fluoride-containing resin-based sealant (F) before and after fluoride release in water. Materials and Methods: We used 40 specimens with 6 mm of height and 20 mm of diameter using fluoride-containing resin-based sealant (FluroShield,Brasil, Dentsply) [...] and non-fluoride-containing resin-based sealant (Concise (TM) Light Cured White Sealant, USA, 3M ESPE). The specimens were divided into four groups, two fluoride-containing resin-based sealants (F1 and F2) and two like control groups (C1 and C2). A group of specimens of fluoride-containing resin-based sealant and a control group (F1/C1) remained without exposure to water, while other groups (F2/C2) were immersed in distilled water for 30 days. The release of fluoride from the F2 was measured through selective electrode method on days 1, 2, 3 and 30. Subsequently, the compressive strength was measured using a universal testing machine (Lloyd, LR 100, UK) with a crosshead speed of 1 mm/min. Comparisons between groups F1 vs F2 and C1 vs C2 were analyzed with t-Student. The significance level was set at 0.05. Results: The compressive strength (Mpa) before and after immersion in water for fluoride-containing resin-based sealant was 337.2 and 337.4, while the control sealant was 203.8 and 213.4. For both groups the observed differences were not significant. The initial fluoride release was 1.9 ppm during the first 24 hours and then declined to 0.0 ppm during the third day of release. Conclusion: In this in vitro study, the release of fluoride from a fluoride-containing resin-based sealant does not affect compressive strength.

C, Vergara; S, Uribe.

330

Modelamiento de la resistencia a la compresión de concretos alternativos, usando la metodología de superficie de respuesta / Modeling of the compressive strength of alternative concretes using the response surface methodology  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish En este artículo se presentan los valores de resistencia a la compresión de concretos alternativos de activación alcalina, basados en mezclas binarias de una escoria siderúrgica (GBFS) y un metacaolín (MK) de alta pureza, a edades de curado de 7, 28, 90 y 180 días. Como activante alcalino se empleó [...] una solución de waterglass (Na2SiO3.nH2O + NaOH), cuya dosificación fue ajustada para lograr una relación molar SiO2/Al2O3 del sistema cementante en un rango entre 3,6 y 4,4. Los resultados a 28 días de curado se analizaron a través de la Metodología de Superficie de Respuesta (M.S.R) considerando como variables en estudio: el contenido de MK en el cementante (CMK) y la relación molar SiO2/Al2O3 (Rm). A partir del modelo estadístico obtenido, se presentan los contornos de resistencia a la compresión de estos materiales en función de los factores en estudio y se predice que los concretos producidos con cementos alternativos con una relación GBFS/(GBFS+MK) de 0,9 y con un Rm de 4,2, podrían desarrollar resistencias a la compresión de hasta 74 MPa. Cabe anotar que los concretos basados en sistemas binarios de GBFS/ MK presentan resistencias a la compresión de hasta 56 MPa y 80 MPa, a 7 y 180 días de curado respectivamente, comportamiento característico de materiales de alto desempeño mecánico. Abstract in english In this paper is to present the compressive strength reported by alternative concrete at ages of curing of 7, 28, 90 and 180 days. These materials were produced applying alkaline activation processes to binary systems based on granulated-blast furnace slag (GBFS) and high purity metakaolin (MK). As [...] alkali-activator a waterglass solution (Na2SiO3.nH2O + NaOH) was used and its dosages were adjusted in order to get a SiO2/Al2O3 molar ratio between 3.6 and 4.4. The results at 28 days of curing were analyzed through the statistical methodology of response surface (M.S.R). As study factors have been considered: the amount of MK into the binder (CMK) and the SiO2/Al2O3 molar ratio in the binder (Rm). From the proposed statistical model the compressive strength contours, as function of the binder variables, are identified and it is predicted that concretes elaborated from alternative binders with a GBFS/(GBFS+MK) ratio of 0.9 and Rm of 4.2, it is possible to obtain compressive strengths up to 74 MPa. It important stand out that concrete composed by binary systems of GBFS/MK to develop compressive strengths up to 56 MPa at 7 days of curing and up to 80 MPa at 180 days of curing, which is expected for high mechanical performance materials.

Susan, Bernal López; Marisol, Gordillo; Ruby, Mejía de Gutiérrez; Erich, Rodríguez Martínez; Silvio, Delvasto Arjona; Robert, Cuero.

331

Compressive strength of glass ionomer cements using different specimen dimensions / Resistência à compressão de cimentos de ionômero de vidro utilizando-se diferentes tamanhos de corpos-de-prova  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este estudo teve como objetivo avaliar a resistência à compressão de dois cimentos de ionômero de vidro, um convencional (Vitro Fil® - DFL) e outro modificado por resina (Vitro Fil LC® - DFL), utilizando-se dois tamanhos de amostras: uma com 6 mm de altura e 4 mm de diâmetro e outra com 12 mm de alt [...] ura e 6 mm de diâmetro, seguindo-se a especificação 7489:1986 da ISO e a especificação n. 66 da ANSI/ADA para Cimento Dental de Ionômero de Vidro, respectivamente. Foram confeccionados 10 corpos-de-prova (CP) de cada material para cada tamanho de amostra, totalizando 40 CP. Estes CP foram armazenados em água destilada e ensaiados 24 horas após a manipulação do material, sob uma carga de compressão em uma Máquina de Ensaio Universal (EMIC) a uma velocidade de 0,5 mm/min. Foi realizada a análise estatística para comparação dos resultados utilizando-se o teste Kruskal-Wallis (5%). As médias dos testes de resistência à compressão (MPa) foram: 54,00 ± 6,6 e 105,10 ± 17,3 para a amostra de 12 mm x 6 mm utilizando-se Vitro Fil e Vitro Fil LC, respectivamente, e 46,00 ± 3,8 e 91,10 ± 8,2 para a amostra de 6 mm x 4 mm utilizando-se Vitro Fil e Vitro Fil LC, respectivamente. O cimento de ionômero de vidro modificado por resina obteve melhores resultados independentemente do tamanho do corpo-de-prova. Para ambos os cimentos de ionômero de vidro, a matriz de 12 mm x 6 mm apresentou maiores valores de resistência que a matriz de 6 mm x 4 mm. Uma maior variabilidade nos resultados pôde ser observada quando os cimentos ionoméricos foram utilizados nas matrizes maiores. Abstract in english 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 hei [...] ght 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.

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

332

Compressive and tensile failure at high fluid pressure where preexisting fractures have cohesive strength, with application to the San Andreas fault  

Science.gov (United States)

In thrusting and strike-slip situations, when the maximum principal horizontal stress S1 acts nearly normal to a fault (a misoriented fault, such as the San Andreas), pore-fluid pressure > the lithostatic load, Pf > Sv, is required to reactivate movement on that fault. Pf > Sv may be achieved without causing hydraulic tensile fracturing if (1) previously existing cracks have regained cohesive strength by chemical processes, (2) subcritical crack growth has been blunted, and (3) the least principal horizontal stress S3 nearly equals Sv. Where Pf > Sv has been attained within a misaligned fault, increasing the stress difference (S1 - S3) at constant Pf > Sv will not lead to shear failure, while a decrease in (S1 - S3) can lead to shear failure of that fault. However, where the cohesive strength of material in a broad misaligned fault zone is less than that of the surrounding intact rock, increasing (S1 - S3) while Pf > Sv can result in shear failure of fractures at near optimum angles to S1, but confined within this weak fault zone. If this faulting results in the local short-lived attainment of Pf > Sv (cataclastic deformation and frictional heating overcoming dilation) and a simultaneous decrease in (S1 - S3), this combination of effects can trigger movement along the main trace of the misaligned fault. When increasing Pf results in hydraulic failure, anisotropy in tensile strength or fracture toughness resulting from foliation within faults allows fractures to propagate along the planes of weakness rather than across the foliation perpendicular to S3.

Fournier, R. O.

1996-01-01

333

Characterization of Erodibility Using Soil Strength and Stress-Strain Indices for Soils in Some Selected Sites in Imo State  

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Full Text Available In this study, initial soil strength indices (qu and stress-strain characteristics namely failure strain (?f; area under the stress-strain curve up to failure (Is and stress-strain modulus between no load and failure (Es were investigated as potential indicators for characterizing the erosion resistance of two compacted soils namely Sandy Clay Loam (SCL and Clay Loam (CL in some selected sites in Imo State, Nigeria. The unconfined compressive strength (used in obtaining strength indices and stress-strain measurements were obtained as a function of moisture content in percentage (mc % and dry density (?d. Test were conducted over a range of 8 to 30% moisture content and 1.0 to 2.0 g/cm3 dry density at applied loads of 20, 40, 80, 160 and 320 kPa. Based on the results, it was found out that initial soil strength alone was not a good indicator of erosion resistance. For instance in the comparison of exponents of mc % and ?d for jet index or erosion resistance index (Ji and the strength measurements, qu and Es (Table 1 agree in signs for mc %, but are opposite in signs for ?d. Therefore there is an inconsistency in exponents making it difficult to develop a relationship between the strength parameters and Ji for this data set. In contrast, the exponents of mc % and ?d for Ji and ?f and Is are opposite in signs (Table 1, there is potential for an inverse relationship. The measured stress-strain characteristics however, appeared to have potential in providing useful information on erosion resistance. The models developed for the prediction of the extent or the susceptibility of soils to erosion and subjected to sensitivity test on some selected sites as shown in Table 2 achieved over 90% efficiency in their functions.

N.A.A. Okereke

2012-07-01

334

Summary and evaluation of available hydraulic property data for the Hanford Site unconfined aquifer system  

International Nuclear Information System (INIS)

Improving the hydrologic characterization of the Hanford Site unconfined aquifer system is one of the objectives of the Hanford Site Ground-Water Surveillance Project. To help meet this objective, hydraulic property data available for the aquifer have been compiled, mainly from reports published over the past 40 years. Most of the available hydraulic property estimates are based on constant-rate pumping tests of wells. Slug tests have also been conducted at some wells and analyzed to determine hydraulic properties. Other methods that have been used to estimate hydraulic properties of the unconfined aquifer are observations of water-level changes in response to river stage, analysis of ground-water mound formation, tracer tests, and inverse groundwater flow models

1992-01-01

335

RELACIÓN ENTRE LA RESISTENCIA A LA COMPRESIÓN Y LA POROSIDAD DEL CONCRETO EVALUADA A PARTIR DE PARÁMETROS ULTRASÓNICOS / RELATIONSHIP BETWEEN COMPRESSIVE STRENGTH AND POROSITY OF CONCRETE EVALUATED FROM ULTRASONIC PARAMETERS  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish El propósito de la presente investigación fue evaluar la resistencia a la compresión y la porosidad en muestras de concreto empleando medidas de velocidad de pulso ultrasónico (VPU) y posteriormente establecer relaciones entre las propiedades estudiadas y la VPU. Las muestras fueron preparadas con d [...] iferentes relaciones agua/cemento (a/c) y curadas durante 28 días en condiciones ambientales bajo techo. El trabajo se planteó teniendo en cuenta que la porosidad es un factor importante que influye en el material, ya que permite el ingreso de agentes agresivos dentro de la matriz del concreto afectando su resistencia a la compresión, y en general disminuyendo el tiempo de vida útil proyectado para la estructura. Estudios anteriores han demostrado que la porosidad depende entre otros factores de la relación a/c empleada en la mezcla. Uno de los métodos para evaluar las estructuras sin afectarlas es el ultrasonido, por medio de este se puede estimar la resistencia mecánica tanto in situ como en laboratorio. La técnica ultrasónica de mayor aplicación es la de VPU. En el presente trabajo se midió la resistencia a la compresión, la porosidad y la VPU a probetas de concreto fabricadas con cemento Portland tipo I y relaciones a/c de 0,45, 0,50, 0,55 y 0,60. Los experimentos fueron llevados a cabo a 7, 14 y 28 días de curado. Este primer trabajo acerca de la aplicación de la técnica de VPU como ensayo no destructivo para la evaluación de la calidad del concreto, permitió verificar el potencial de la técnica como medio para estimar el comportamiento del material durante el tiempo de este estudio. Abstract in english The purpose of this research was to evaluate the compressive strength and porosity of concrete samples using ultrasonic pulse velocity (UPV) measurements and then establish relationships between the studied properties and the UPV. The samples were prepared with different water/cement ratios (w/c) an [...] d cured for 28 days at indoor environmental conditions. This work was raised taking into account that porosity is an important factor that influences the material, allowing aggressive agents to enter the concrete matrix affecting its compressive strength, and in general decreasing the projected lifetime of the structure. Previous studies have proved that porosity strongly depends on the water/cement ratio (w/c) used for the mixture. One method to evaluate structures without affecting them is ultrasounds. Through this technique, mechanical resistance can be estimated both in situ and in laboratory. The ultrasonic technique that is widely used is the ultrasonic pulse velocity (UPV). In this paper the compressive strength, the porosity, and the ultrasonic pulse velocity were measured in concrete test tubes manufactured with Portland cement type I, using water/cement ratios of 0.45, 0.50, 0.55, and 0.60. The experiments were carried out at 7, 14 y 28 curing days. This first work about UPV technique application as a non-destructive testing for assessing concrete quality, allowed studying the potential of technique itself, as a means to estimate the material behavior, in this case during the curing stage under environment conditions.

QUINTERO ORTÍZ, LUZ AMPARO; HERRERA, JULIAN; CORZO, LAURA; GARCÍA, JOHANA.

336

Neutralization of acid mine drainage using fly ash, and strength development of the resulting solid residues  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Acid mine drainage (AMD) from a South African coal mine was neutralized with fly ash (FA) from a local power station. An immediate increase in pH and subsequent decrease in the electrical conductivity (EC) values were observed with the addition of FA. A pH buffering region was observed for all the A [...] MD:FA ratios investigated. This was attributed to precipitation and hydrolysis of the main AMD constituents such as Al and Fe and adsorption of the precipitates upon the ash particles. A high percentage of major, minor and trace elements and SO4(2-) attenuation was achieved after contact of AMD with FA in solution; this removal depended on the final pH of the product water. Most of the contaminants were removed to acceptable levels in one simple procedure by contacting the AMD with FA in suitable ratios. Solid residues (SR) recovered from neutralization reactions were tested for unconfined compressive strength and elastic modulus in order to assess their suitability as backfill material. Strength testing was carried out for 410 days with and without the addition of ordinary Portland cement. The SR with a pozzolanic binder added gained 300% greater strength than without, both of which increased in strength over time. The implementation of this FA treatment process would not only be environmentally beneficial but also would be to the advantage of coal mines and power stations as a way of constructively using the large volumes of waste that they generate.

Vadapalli, V.R. Kumar; Klink, M.J.; Etchebers, O.; Petrik, L.F.; Gitari, W.; White, R.A.; Key, D.; Iwuoha, E..

337

Efecto de la adición mineral cal- zeolita sobre la resistencia a la compresión y la durabilidad de un hormigón / Effect of lime- zeolite binder on compression strength and durability properties of a concrete  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish La práctica internacional reporta una creciente utilización de los hormigones de altas resistencias, con excelentes resultados en la durabilidad, relacionado con la obtención de una matriz cementicia muy densa, a partir del empleo de altos volúmenes de adiciones minerales muy finas, tales como las c [...] enizas volantes, la microsílice, el metacaolín y otros materiales. Para los países emergentes, entre los cuales se ubica Cuba, el uso de estas adiciones puzolánicas resultan una solución relativamente costosa, dado los altos precios de importación de estos materiales puzolánicos, de ahí la utilidad de usar las fuentes nacionales de puzolanas disponibles de probada reactividad, como sustituías parciales de los contenidos de Cemento Portland Ordinario (CPO) en las mezclas de hormigón, sin que se vean afectadas significativamente sus propiedades. El presente trabajo muestra la influencia del nivel de sustitución de los contenidos de Cemento Portland por adición mineral cal- puzolana, en combinación con superplastificante, en el comportamiento de la resistencia a la compresión y la durabilidad de un hormigón. Varios niveles de sustitución de CPO son evaluados, utilizando toba zeolítica como puzolana. Los resultados obtenidos corroboran la posibilidad del reemplazo de altos volúmenes de CPO por aglomerante cal-zeolita, sin que se afecten la resistencia a compresión requerida y su comportamiento ante la acción del ingreso del ion cloruro y la carbonatación. Abstract in english The international construction practice reports a remarkable use and development of high performance concretes, with excellent results in the durability properties, associated with a very dense cement matrix, defined from the use of high volumes of very fine minerals additions, such as, fly ash, sil [...] ica fume, metakaolin and other fine powders. For the developing countries, among others Cuba, the use of these pozzolanic additions are relatively expensive, given for the high import prices of these pozzolanic materials, thus, the utility of using the national available pozzolanic sources with proven reactivity, as a partial substitute of the Ordinary Portland Cement (OPC) contents in the concrete mixtures without its properties are affected. The present paper shows the results of the study on the influence of substitution level of Ordinary Portland Cement contents by lime - pozzolan binder in combination with chemical admixture, in the behavior of the compression strength and the durability properties of a concrete. Several levels of OPC substitution are evaluated, using zeolite as pozzolan. The results obtained prove the possibility to carry out the partial replacement of high volumes of OPC by lime - zeolite binder, without affecting the values of compression strength required and their behavior before action of the chloride ion penetration and the carbonation.

Juan José, Dopico Montes de Oca; José Fernando, Martirena Hernandez; Alberto, López Rodríguez; Raúl, González López.

338

Efecto de la adición mineral cal- zeolita sobre la resistencia a la compresión y la durabilidad de un hormigón Effect of lime- zeolite binder on compression strength and durability properties of a concrete  

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Full Text Available La práctica internacional reporta una creciente utilización de los hormigones de altas resistencias, con excelentes resultados en la durabilidad, relacionado con la obtención de una matriz cementicia muy densa, a partir del empleo de altos volúmenes de adiciones minerales muy finas, tales como las cenizas volantes, la microsílice, el metacaolín y otros materiales. Para los países emergentes, entre los cuales se ubica Cuba, el uso de estas adiciones puzolánicas resultan una solución relativamente costosa, dado los altos precios de importación de estos materiales puzolánicos, de ahí la utilidad de usar las fuentes nacionales de puzolanas disponibles de probada reactividad, como sustituías parciales de los contenidos de Cemento Portland Ordinario (CPO en las mezclas de hormigón, sin que se vean afectadas significativamente sus propiedades. El presente trabajo muestra la influencia del nivel de sustitución de los contenidos de Cemento Portland por adición mineral cal- puzolana, en combinación con superplastificante, en el comportamiento de la resistencia a la compresión y la durabilidad de un hormigón. Varios niveles de sustitución de CPO son evaluados, utilizando toba zeolítica como puzolana. Los resultados obtenidos corroboran la posibilidad del reemplazo de altos volúmenes de CPO por aglomerante cal-zeolita, sin que se afecten la resistencia a compresión requerida y su comportamiento ante la acción del ingreso del ion cloruro y la carbonatación.The international construction practice reports a remarkable use and development of high performance concretes, with excellent results in the durability properties, associated with a very dense cement matrix, defined from the use of high volumes of very fine minerals additions, such as, fly ash, silica fume, metakaolin and other fine powders. For the developing countries, among others Cuba, the use of these pozzolanic additions are relatively expensive, given for the high import prices of these pozzolanic materials, thus, the utility of using the national available pozzolanic sources with proven reactivity, as a partial substitute of the Ordinary Portland Cement (OPC contents in the concrete mixtures without its properties are affected. The present paper shows the results of the study on the influence of substitution level of Ordinary Portland Cement contents by lime - pozzolan binder in combination with chemical admixture, in the behavior of the compression strength and the durability properties of a concrete. Several levels of OPC substitution are evaluated, using zeolite as pozzolan. The results obtained prove the possibility to carry out the partial replacement of high volumes of OPC by lime - zeolite binder, without affecting the values of compression strength required and their behavior before action of the chloride ion penetration and the carbonation.

Juan José Dopico Montes de Oca

2009-08-01

339

THE INFLUENCE OF MOLDING WATER CONTENT AND LIME CONTENT ON THE STRENGTH OF STABILIZED SOIL WITH LIME AND RICE HUSK ASH  

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Full Text Available The strength gain of stabilized soils is not only influenced by the type and proportion of the stabilizers and its curing time, but also by the water content needed to maintain the reaction. The reaction of lime – RHA with soil is pozzolanic. Hence, the process will be subjected greatly by the amount of water to react with admixtures and the proportion of the stabilizer. This paper presents the result of a laboratory study on the unconfined compressive strength (UCS of soils stabilized with lime and RHA, compacted at the OMC, and at the dry and wet side of OMC. The amount of lime required for stabilization (LRS is determined by Eades and Grim's Method. The results showed that the water content determines the UCS characteristics of unstabilized and stabilized soils. The UCS of stabilized soils decreased with increasing molding water content, but it is still higher than of the un-stabilized soils. In general, higher lime content results to a higher UCS. The maximum strength of the stabilized soil is attained at lime/RHA ratio of 1/2. The UCS of the stabilized soil increased significantly about 7 – 9 times to the un-stabilized UCS.

Agus Setyo Muntohar

2005-01-01

340

Statistical Evaluation of Model Rock Compressive Strength  

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Full Text Available Poèas razenia východnej èasti prieskumnej ?tôlne Branisko bol na plnoprofilový raziaci stroj Wirth TBII-330-H/M in?talovaný monitorovací a optimalizaèný systém WORS, vyvinutý na Ústave geotechniky SAV. Systém umo?òoval výpoèty v reálnom èase velièín ako ?pecifická energia rozpojovania a odporuèený prítlak raziacej hlavy. Údaje získané monitorovaním boli následne pou?ité ako vstupy do matematického modelu systému IKONA, ktorý umo?òoval previes parametre procesu razenia na parametre horninového masívu. Jednou z takto urèovaných velièín bola i modelová tlaková pevnos horniny, ktorej ?tatistické hodnotenie je uvedené v èlánku. Bola skúmaná vhodnos rôznych rozdelení pravdepodobnosti pre popis modelovej pevnosti v jednotlivých geologických úsekoch prieskumného tunela Branisko. Z analýzy je zrejmé, ?e pevný celistvý horninový masív najlep?ie charakterizuje normálne rozdelenie, zatia¾ èo masív poru?ený zlomami a diskontinuitami je vhodnej?ie popisova lognormálnym alebo Weibullovým rozdelením.

Lucia Ivani?ová

2004-12-01

 
 
 
 
341

Stochastic inversion of sequential hydraulic tests for transient and highly permeable unconfined aquifer systems  

Science.gov (United States)

A hydraulic tomography survey (HTS) is a conceptually improved technique that has been recognized to be efficient for estimating high-resolution aquifer parameters. Based on the concept of HTS, this study presents a modified stochastic inverse model for estimating hydraulic conductivity (K) and specific yield (Sy) in shallow and highly permeable unconfined aquifers. A well field with 15 fully screened wells was developed for the purpose of model implementations. In this study a synthetic example was first employed to assess the accuracy of the inverse model. We then implemented the model to field-scale, cross-hole injection tests in a shallow and highly permeable unconfined aquifer near the middle reach of the Wu River in central Taiwan. To assess the effect of constant head boundary conditions on the estimation results, two additional modeling domains were evaluated based on the same field data from the injection tests. Results for the synthetic example show that the modified inverse model can reproduce well the predefined geologic features of the unconfined aquifer. The inverse model can estimate accurately the ln K patterns and magnitudes. However, slightly fewer details of the ln Sy field are obtained due to the insensitivity of transient hydraulic stresses for specified sampling times. Model implementations of field-scale injection tests show that the model can estimate ln K and ln Sy fields with high spatial resolution. The estimated K and Sy values for the test site vary by one order of magnitude, indicating a relatively homogeneous aquifer for the tested well field. Results based on three different modeling domains show similar patterns and magnitudes of ln K and ln Sy near the well locations. This result suggests that the case with domain 40 m × 20 m should be sufficient for the injection tests at the well field.

Ni, C.-F.; Huang, Y.-J.; Yeh, T.-C. J.; Dong, J.-J.; Chen, J.-S.; Li, M.-H.

2013-12-01

342

Numerical study of two-phase unconfined fuel-air cloud characteristics to consider its detonability  

International Nuclear Information System (INIS)

A numerical simulation is introduced to study the characteristics of unconfined fuel-air mixture in order to study its detonability. A modified version of KIVA-3V code is used to model the dispersal process. Some models are applied to determine the initial conditions, and a comparison is made between the results of these models. The outcome of this study can be used to predict the best time and position for secondary ignition action to detonate the cloud. A theoretical consideration along with a comparison with other works is made for validation. (author)

2002-06-09

343

Recent Advances in Studies of the Strength of Rocks Under True Triaxial Compression Conditions / POST?PY W Badaniach Nad WYTRZYMA?O?CI? SKA? W Warunkach Prawdziwego TRÓJOSIOWEGO ?CISKANIA  

Science.gov (United States)

The results of true triaxial compression tests carried out by K. Mogi at the University of Tokyo, M. Takahashi at the Geological Survey of Japan and B. Haimson at the University of Wisconsin are summarized and the effect of the intermediate principal stress on the ultimate strength of rocks is discussed in the first part of the paper. Then, the Huber-Mises-Hencky failure theory, which was generalized by Nádai and further modified by Mogi to explain the stress-dependency of both the brittle fracturing and the ductile flow of rocks, is revisited. In the main part of the paper, the results of recent experimental studies carried out on samples of a Coal-Measure sandstone from the strata of the Upper Silesian Coal Basin under true triaxial compression conditions are presented. The studies focused on the effect of, independently, confining pressure, intermediate principal stress and minimum principal stress on the ultimate strength of this rock. The paper closes with a presentation and discussion of a general failure criterion that is capable of predicting the ultimate strength of rocks under both axisymmetric and true triaxial (asymmetric) compressive stress conditions. W pierwszej cz??ci artyku?u podsumowano wyniki bada? eksperymentalnych na prawdziwe trójosiowe ?ciskanie przeprowadzonych przez K. Mogiego z Uniwersytetu Tokijskiego, M. Takahashiego z Japo?skiego Instytutu Geologicznego i B. Haimsona z Uniwersytetu Wisconsin i omówiono wp?yw po?redniego napr??enia g?ównego na wytrzyma?o?? graniczn? ska?. Nast?pnie, przypomniano uogólnion? przez Nádai'a hipotez? wyt??eniow? Hubera-Misesa-Hencky'ego, któr? przed laty zmodyfikowa? Mogi ?eby wyja?ni? zale?no?? granicznego stycznego napr??enia oktaedrycznego od tzw. efektywnego napr??enia ?redniego dla, oddzielnie, ska? zachowuj?cych si? krucho i ska? doznaj?cych przy ?ciskaniu ci?gliwego p?yni?cia. W g?ównej cz??ci artyku?u przedstawiono wyniki najnowszych bada? eksperymentalnych przeprowadzonych na próbkach pewnego piaskowca z górotworu Górno?l?skiego Zag??bia W?glowego (by?to drobnoziarnisty arenit kwarcowy o stosunkowo wysokiej, równej oko?o 146 MPa, wytrzyma?o?ci granicznej na jednoosiowe ?ciskanie). Celem tych bada? by?o wykrycie wp?ywu, oddzielnie, ci?nienia okólnego (p = ?2 = ?3), po?redniego napr??enia g?ównego (?2) i najmniejszego napr??enia g?ównego (?3) na wytrzyma?o?? graniczn? tej ska?y. W próbach na konwencjonalne trójosiowe ?ciskanie wytrzyma?o?? badanego piaskowca silnie ros?a ze wzrostem ci?nienia okólnego. Przy ci?nieniu równym 62,5 MPa, graniczne najwi?ksze napr??enie g?ówne (F?1) by?o, ?rednio, 2,8 razy wi?ksze od tego zanotowanego w próbach na jednoosiowe ?ciskanie. Wyniki prób na prawdziwie trójosiowe ?ciskanie pokaza?y, ?e wp?yw po?redniego napr??enia g?ównego (?2) na wytrzyma?o?? graniczn? badanego piaskowca - chocia? ewidentny i znacz?cy - jest jednak wyra?nie s?abszy ni? wp?yw ci?nienia okólnego (rys. 19). W przypadku próbek badanych przy najmniejszym napr??eniu g?ównym (?3) równym 25 MPa, najwi?ksze napr??enie g?ówne na granicy wytrzyma?o?ci odpowiadaj?ce napr??eniu po?redniemu ?2 = 62,5 MPa by?o tylko o 19% wi?ksze ni? to odpowiadaj?ce napr??eniu ?2 = 25 MPa. Zaobserwowano przy tym, ?e tempo wzrostu wytrzyma?o?ci ze wzrostem po?redniego napr??enia g?ównego (w przedziale od 25 MPa do 62,5 MPa) nieznacznie maleje. Badania nad wp?ywem najmniejszego napr??enia g?ównego na wytrzyma?o?? graniczn? pokaza?y, ?e napr??enie to odgrywa rol? podobn? do roli napr??enia po?redniego (?2). Jednak?e, tempo wzrostu wytrzyma?o?ci badanej ska?y ze wzrostem ?3 by?o nieco wi?ksze od tego zaobserwowanego gdy zwi?kszano ?2 przy sta?ym ?3 (rys. 20). Przy po?rednim napr??eniu g?ównym równym 62,5 MPa, graniczne najwi?ksze napr??enie g?ówne (F?1) odpowiadaj?ce ?3 = 62,5 MPa by?o wy?sze o blisko 28% od tego odpowiadaj?cego napr??eniu ?3 równemu 25 MPa. Silniej

Kwa?niewski, Marek

2013-12-01

344

Material properties in unconfined compression of human nucleus pulposus, injectable hyaluronic acid-based hydrogels and tissue engineering scaffolds  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Surgical treatment for lower back pain related to degenerative disc disease commonly includes discectomy and spinal fusion. While surgical intervention may provide short-term pain relief, it results in altered biomechanics of the spine and may lead to further degenerative changes in adjacent segments. One non-fusion technique currently being investigated is nucleus pulposus (NP) support via either an injectable hydrogel or tissue engineered construct. A major challenge for either approach is ...

Cloyd, Jordan M.; Malhotra, Neil R.; Weng, Lihui; Chen, Weiliam; Mauck, Robert L.; Elliott, Dawn M.

2007-01-01

345

Strength Measurements of Archive K Basin Sludge Using a Soil Penetrometer  

Energy Technology Data Exchange (ETDEWEB)

Spent fuel radioactive sludge present in the K East and K West spent nuclear fuel storage basins now resides in the KW Basin in six large underwater engineered containers. The sludge will be dispositioned in two phases under the Sludge Treatment Project: (1) hydraulic retrieval into sludge transport and storage containers (STSCs) and transport to interim storage in Central Plateau and (2) retrieval from the STSCs, treatment, and packaging for shipment to the Waste Isolation Pilot Plant. In the years the STSCs are stored, sludge strength is expected to increase through chemical reaction, intergrowth of sludge crystals, and compaction and dewatering by settling. Increased sludge strength can impact the type and operation of the retrieval equipment needed prior to final sludge treatment and packaging. It is important to determine whether water jetting, planned for sludge retrieval from STSCs, will be effective. Shear strength is a property known to correlate with the effectiveness of water jetting. Accordingly, the unconfined compressive strengths (UCS) of archive K Basin sludge samples and sludge blends were measured using a pocket penetrometer modified for hot cell use. Based on known correlations, UCS values can be converted to shear strengths. Twenty-six sludge samples, stored in hot cells for a number of years since last being disturbed, were identified as potential candidates for UCS measurement and valid UCS measurements were made for twelve, each of which was found as moist or water-immersed solids at least 1/2-inch deep. Ten of the twelve samples were relatively weak, having consistencies described as 'very soft' to 'soft'. Two of the twelve samples, KE Pit and KC-4 P250, were strong with 'very stiff' and 'stiff' consistencies described, respectively, as 'can be indented by a thumb nail' or 'can be indented by thumb'. Both of these sludge samples are composites collected from KE Basin floor and Weasel Pit locations. Despite both strong sludges having relatively high iron concentrations, attribution of their high strengths to this factor could not be made with confidence as other measured sludge samples, also from the KE Basin floor and of high iron concentration, were relatively weak. The observed UCS and shear strengths for the two strong sludges were greater than observed in any prior testing of K Basin sludge except for sludge processed at 185 C under hydrothermal conditions.

Delegard, Calvin H.; Schmidt, Andrew J.; Chenault, Jeffrey W.

2011-12-06

346

Approaches to the simulation of unconfined flow and perched groundwater flow in MODFLOW.  

Science.gov (United States)

Various approaches have been proposed to manage the nonlinearities associated with the unconfined flow equation and to simulate perched groundwater conditions using the MODFLOW family of codes. The approaches comprise a variety of numerical techniques to prevent dry cells from becoming inactive and to achieve a stable solution focused on formulations of the unconfined, partially-saturated, groundwater flow equation. Keeping dry cells active avoids a discontinuous head solution which in turn improves the effectiveness of parameter estimation software that relies on continuous derivatives. Most approaches implement an upstream weighting of intercell conductance and Newton-Raphson linearization to obtain robust convergence. In this study, several published approaches were implemented in a stepwise manner into MODFLOW for comparative analysis. First, a comparative analysis of the methods is presented using synthetic examples that create convergence issues or difficulty in handling perched conditions with the more common dry-cell simulation capabilities of MODFLOW. Next, a field-scale three-dimensional simulation is presented to examine the stability and performance of the discussed approaches in larger, practical, simulation settings. PMID:21635246

Bedekar, Vivek; Niswonger, Richard G; Kipp, Kenneth; Panday, Sorab; Tonkin, Matthew

2012-01-01

347

Reflections about the modelling of unconfined explosions of air-hydrocarbon mixtures  

International Nuclear Information System (INIS)

To design nuclear power plants structures, an evaluation of hazards which can be induced by the industrial activities is needed. These hazards namely involve explosions of flamable air-hydrocarbon gas clouds. Such clouds can drift before ignition, and, when ignited, the generated pressure wave can cause serious damage, even far from the initial accident location. When the designs an industrial plant, the designer has to predict the overpressures capable of jeopardizing the safety functions of the plant. The analysis of real accidental explosions which have actually occurred, on the basis of a total explosion yield and the TNT equivalency concept, is a first step. Indeed, it allows a total explosion yield to be calculated, an empirical TNT equivalent of hydrocarbon to be deducted. Unfortunately, this TNT equivalency concept is scientifically not satisfying. The modelling of an unconfined air-hydrocarbon detonation can be used for safety analysis, if we assume that an unconfined explosion can be a detonation, which is unlikely. (orig./WL)

1983-01-01

348

Compressive behaviour of unidirecterional flax fibre reinforced composites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The compressive strength of unidirectional flax fibre epoxy composites was studied. The compressive strength is influenced negatively by the presence of kink bands in the flax fibres. Improvement of the adhesion between the fibres and the epoxy resin can be achieved easily by removing the thin wax layer which covers the surface of the flax fibres. However, improving the adhesion between fibres and matrix only improves the compressive strength to a very limited extent. Stabilisation of the kin...

Bos, H. L.; Molenveld, K.; Teunissen, W.; Wingerde, A. M.; Delft, D. R. V.

2004-01-01

349

Pushdown compression  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The pressing need for efficient compression schemes for XML documents has recently been focused on stack computation (Hariharan and Shankar 2006, League and Eng 2007), and in particular calls for a formulation of information-lossless stack or pushdown compressors that allows a formal analysis of their performance and a more ambitious use of the stack in XML compression, where so far it is mainly connected to parsing mechanisms. In this paper we introduce the model of pushdown compressor, base...

Albert, Pilar; Mayordomo, Elvira; Moser, Philippe; Perifel, Sylvain

2008-01-01

350

Finite-difference interblock transmissivity for unconfined aquifers and for aquifers having smoothly varying transmissivity  

Science.gov (United States)

More accurate alternatives to the widely used harmonic mean interblock transmissivity are proposed for block-centered finite-difference models of ground-water flow in unconfined aquifers and in aquifers having smoothly varying transmissivity. The harmonic mean is the exact interblock transmissivity for steady-state one-dimensional flow with no recharge if the transmissivity is assumed to be spatially uniform over each finite-difference block, changing abruptly at the block interface. However, the harmonic mean may be inferior to other means if transmissivity varies in a continuous or smooth manner between nodes. Alternative interblock transmissivity functions are analytically derived for the case of steady-state one-dimensional flow with no recharge. The second author has previously derived the exact interblock transmissivity, the logarithmic mean, for one-dimensional flow when transmissivity is a linear function of distance in the direction of flow. We show that the logarithmic mean transmissivity is also exact for uniform flow parallel to the direction of changing transmissivity in a two- or three-dimensional model, regardless of grid orientation relative to the flow vector. For the case of horizontal flow in a homogeneous unconfined or water-table aquifer with a horizontal bottom and with areally distributed recharge, the exact interblock transmissivity is the unweighted arithmetic mean of transmissivity at the nodes. This mean also exhibits no grid-orientation effect for unidirectional flow in a two-dimensional model. For horizontal flow in an unconfined aquifer with no recharge where hydraulic conductivity is a linear function of distance in the direction of flow the exact interblock transmissivity is the product of the arithmetic mean saturated thickness and the logarithmic mean hydraulic conductivity. For several hypothetical two- and three-dimensional cases with smoothly varying transmissivity or hydraulic conductivity, the harmonic mean is shown to yield the least accurate solution to the flow equation of the alternatives considered. Application of the alternative interblock transmissivities to a regional aquifer system model indicates that the changes in computed heads and fluxes are typically small, relative to model calibration error. For this example, the use of alternative interblock transmissivities resulted in an increase in computational effort of less than 3 percent. Numerical algorithms to compute alternative interblock transmissivity functions in a modular three-dimensional flow model are presented and documented.

Goode, D. J.; Appel, C. A.

1992-01-01

351

Shear Strength  

Science.gov (United States)

Dr. John Atkinson, of the University of the West of England, developed a site for undergraduate students wanting to learn more about soil classification. His site addresses issues such as: shear strength, peak strength, and residual strength testing. Filled with charts, diagrams, statistics, the information is pertinent and easily understood by almost any audience.

Atkinson, John

2008-10-07

352

Manufacture and compression properties of syntactic foams  

Science.gov (United States)

A study has been made of the processability, bulk density, and uniaxial compression properties of a syntactic foam system with varying volume fractions of phenolic microballoons. Short-term compression tests showed that the compression yield strength and initial tangent modulus of elasticity were linearly dependent on the bulk density (and the volume fraction of microballoons). The microballoon concentration and resin binder composition was found to be crucial to the ease of manufacturing syntactic foams.

Bunn, P.; Mottram, J. T.

1993-10-01

353

Investigating the Effect of Concrete Strength on the Behaviour of Composite Steel-concrete Beams  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The present study investigates the effects of increasing the compressive strength of concrete deck on the deflection at midspan and slip at ends of steel-concrete composite beam. In the present study, four groups of steel concrete composite beam were tested to investigate the effects of variation of concrete compressive strength on the deflection, slip, yield strength and ultimate strength of composite beam, using concrete cylinder compressive strength of 21, 42 and 64 MPa. The study al...

Suhaib Yahya Kasim Al-Darzi; Ameer, Usama A.

2012-01-01

354

Strength Modeling of High-Strength Concrete with Hybrid Fibre Reinforcement  

Directory of Open Access Journals (Sweden)

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

A. Ravichandran

2009-01-01

355

3D Simulation of Internal Tablet Strength During Tableting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study presents a new approach to model powder compression during tableting. The purpose of this study is to introduce a new discrete element simulation model for particle–particle bond formation during tablet compression. This model served as the basis for calculating tablet strength distribution during a compression cycle. Simulated results were compared with real tablets compressed from microcrystalline cellulose/theophylline pellets with various compression forces. Simulated and exp...

2011-01-01

356

Improved Multiaxial Creep-Rupture Strength Criterion.  

Science.gov (United States)

An improved strength model is developed for predicting creep-rupture under multiaxial stress states. The new model incorporates four stress parameters and distinguishes between life under tensile versus compressive stress states. Assessments of the new mo...

R. L. Huddleston

1984-01-01

357

Wellhead compression  

Energy Technology Data Exchange (ETDEWEB)

Over time, all wells experience a natural decline in oil and gas production. In gas wells, the major problems are liquid loading and low downhole differential pressures which negatively impact total gas production. As a form of artificial lift, wellhead compressors help reduce the tubing pressure resulting in gas velocities above the critical velocity needed to surface water, oil and condensate regaining lost production and increasing recoverable reserves. Best results come from reservoirs with high porosity, high permeability, high initial flow rates, low decline rates and high total cumulative production. In oil wells, excessive annulus gas pressure tends to inhibit both oil and gas production. Wellhead compression packages can provide a cost effective solution to these problems by reducing the system pressure in the tubing or annulus, allowing for an immediate increase in production rates. Wells furthest from the gathering compressor typically benefit the most from wellhead compression due to system pressure drops. Downstream compressors also benefit from higher suction pressures reducing overall compression horsepower requirements. Special care must be taken in selecting the best equipment for these applications. The successful implementation of wellhead compression from an economical standpoint hinges on the testing, installation and operation of the equipment. Key challenges and suggested equipment features designed to combat those challenges and successful case histories throughout Latin America are discussed below.(author)

Harrington, Joe [Sertco Industries, Inc., Okemah, OK (United States); Vazquez, Daniel [Hoerbiger Service Latin America Inc., Deerfield Beach, FL (United States); Jacobs, Denis Richard [Hoerbiger do Brasil Industria de Equipamentos, Cajamar, SP (Brazil)

2012-07-01

358

Mechanical strength properties of gypsum/aggregate mixtures for applications in stemming design  

Energy Technology Data Exchange (ETDEWEB)

A series of stress-strain tests was performed on a mixture of gypsum cement and tuff aggregate used as a stemming material for emplacement holes in underground nuclear testing. Purpose was to evaluate the failure strength of the stemming material as a function of pressure. The material was tested at confining pressures ranging up to 3000 psi at a strain rate of 10/sup -4/s/sup -1/, and in an unconfined state at strain rates of 10/sup -4/ s/sup -1/ and 10/sup -1/ s/sup -1/. In the tests at low strain rates, the strength increased from a range of about 1000 to 1500 psi unconfined to about 6000 to 8000 psi at 2000-psi confinement. The unconfined material was generally somewhat weaker at a strain rate of 10/sup -1/ s/sup -1/ than at 10/sup -4/ s/sup -1/. Strength also decreased with increasing moisture at low strain rate, but no trend could be discerned at the higher strain rate.

Kusubov, A.S.; Anderson, G.D.

1984-02-01

359

Establishment of earth tides effect on water level fluctuations in an unconfined hard rock aquifer using spectral analysis  

CERN Document Server

Short-interval water level measurements using automatic water level recorder in a deep well in an unconfined crystalline rock aquifer at the campus of NGRI, near Hyderabad shows a cyclic fluctuation in the water levels. The observed values clearly show the principal trend due to rainfall recharge. Spectral analysis was carried out to evaluate correlation of the cyclic fluctuation to the synthetic earth tides as well as groundwater withdrawal time series in the surrounding. It was found that these fluctuations have considerably high correlation with earth tides whereas groundwater pumping does not show any significant correlation with water table fluctuations. It is concluded that earth tides cause the fluctuation in the water table. These fluctuations were hitherto unobserved during manual observations made over larger time intervals. It indicates that the unconfined aquifer is characterised by a low porosity.

Maréchal, Jean-Christophe; Ahmed, Shakeel; Lachassagne, Patrick

2010-01-01

360

Compressed Counting  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Counting is among the most fundamental operations in computing. For example, counting the pth frequency moment has been a very active area of research, in theoretical computer science, databases, and data mining. When p=1, the task (i.e., counting the sum) can be accomplished using a simple counter. Compressed Counting (CC) is proposed for efficiently computing the pth frequency moment of a data stream signal A_t, where 0

Li, Ping

2008-01-01

 
 
 
 
361

Establishment of earth tides effect on water level fluctuations in an unconfined hard rock aquifer using spectral analysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Short-interval water level measurements using automatic water level recorder in a deep well in an unconfined crystalline rock aquifer at the campus of NGRI, near Hyderabad shows a cyclic fluctuation in the water levels. The observed values clearly show the principal trend due to rainfall recharge. Spectral analysis was carried out to evaluate correlation of the cyclic fluctuation to the synthetic earth tides as well as groundwater withdrawal time series in the surrounding. It was found that t...

Mare?chal, Jean-christophe; Sarma, Mp; Ahmed, Shakeel; Lachassagne, Patrick

2002-01-01

362

Shock-compression properties of ceramics  

Energy Technology Data Exchange (ETDEWEB)

High-resolution, time-resolved shock compression measurements have been performed on high-strength monolithic ceramics to assess equation-of-state, phase transformation and flow properties. A substantial base of data has been obtained on a range of ceramics including aluminium nitride, aluminum oxide, boron carbide, silicon carbide, titanium diboride and zirconium dioxide. These data provide material response properties for nonlinear elastic compliance, pressure-induced phase transformation, shear strength and tensile fracture strength. 14 refs., 8 figs.

Grady, D.

1991-01-01

363

Measurement of streaming potentials generated during laboratory simulation of unconfined aquifer pumping tests  

Science.gov (United States)

The streaming potential method has emerged as a promising technology for indirect acquisition of spatially dense measurements of the hydraulic system state response to pumping aquifers. The method relies on measurements of electric potentials generated by groundwater flow due to the existence of the electric double layer at the rock--water interface. Mathematical solutions describing the transient electric potentials associated with pumping tests have been recently developed and demonstrated to yield reasonable estimates of hydraulic parameters (Malama et al., 2009b,a). We present results of laboratory experiments conducted to investigate the applicability of the unconfined aquifer model under controlled conditions in a sand tank instrumented with pressure transducers and non-polarizable electrodes. The measured pressure and streaming potential changes under various pumping rates are presented and discussed. Measurements show unambiguous transient streaming potential responses to groundwater flow in bounded cylindrical system. Parameters estimated from streaming potential data are compared to those from drawdown data. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Malama, B.

2011-12-01

364

Theory of transient streaming potentials associated with axial-symmetric flow in unconfined aquifers  

Science.gov (United States)

We present a semi-analytical solution for the transient streaming potential response of an unconfined aquifer to continuous constant rate pumping. We assume that flow occurs without leakage from the unit below a transverse anisotropic aquifer and neglect flow in the unsaturated zone by treating the water-table as a moving material boundary. In the development of the solution to the streaming potential problem, we impose insulating boundary conditions at land surface and the lower boundary of the lower confining unit. We solve the problem exactly in the double Laplace-Hankel transform space and obtain the inverse transforms numerically. The solution is used to analyse transient streaming potential data collected during dipole hydraulic tests conducted at the Boise Hydrogeophysical Research Site in 2007 June. This analysis yields estimates of aquifer hydraulic parameters. The estimated hydraulic parameters, namely, hydraulic conductivity, transverse hydraulic anisotropy, specific storage and specific yield, compare well to published estimates obtained by inverting drawdown data collected at the field site.

Malama, Bwalya; Kuhlman, Kristopher L.; Revil, André

2009-11-01

365

Capture zone of a multi-well system in confined and unconfined wedge-shaped aquifers  

Science.gov (United States)

In this paper we present the equation of capture zone of a multi-well system in wedge-shaped confined and unconfined aquifers. Three wedge boundary configurations: barrier-barrier wedge, barrier-constant head wedge and constant head-constant head wedge are considered. The well system may be consisted of any number of production or injection wells or a combination of both with various flow rates. Method of image wells is used in the wedge-shaped domain and an appropriate complex function is formulated to find the capture zone. The stream function and velocity potential are derived from the imaginary part and real part of the complex function, respectively. Solutions are provided for the wedge domains with and without a uniform regional flow and can also be used for aquifers of infinite extent. The presented equations are of general character and have removed the limitations of the previous equations in regards to well numbers, positions and types, extraction/injection rate, and regional flow rate and direction. Capture envelopes are presented in dimensionless form which can be used as tools in real engineering practices to plan pump-and-treat operations, groundwater remediation projects or well-head protection plans. It is also demonstrated that the equations may also be used for the verification of numerical models. The developed equations are constrained by the image well theory limitations.

Samani, Nozar; Zarei-Doudeji, Somayeh

2012-04-01

366

Theory of transient streaming potentials in coupled unconfined aquifer-unsaturated zone flow to a well  

Science.gov (United States)

semianalytical solution is presented for transient streaming potentials associated with flow to a pumping well in an unconfined aquifer, taking into account the effect of flow in the unsaturated zone above the water table. Flow in the unsaturated zone is modeled with a linearized form of Richards' equation using an exponential model for soil moisture retention and unsaturated hydraulic conductivity. Archie's law is invoked for unsaturated electrical conductivity. The unsaturated electrokinetic coupling coefficient is modeled with a decaying exponential, where the maximum value is at and below the water table. The coupled flow and electrokinetic problem is solved using Laplace and Hankel transforms. The results of the model predicted behavior are presented and compared to that observed in laboratory simulations of pumping tests. The early time polarity reversal predicted the model is observable in the experiments. Other nonmonotonic streaming potential behaviors predicted by the model are also evident in experimental measurements. The model is used to estimate hydraulic parameters from SP data and these compare well to those obtained from drawdown data. For example, a hydraulic conductivity of 3.6 × 10-4 m/s is obtained from SP data compared to 3.4 × 10-4 m/s from drawdown data.

Malama, Bwalya

2014-04-01

367

Effects of cereal production on nutrient dynamics of shallow, unconfined aquifers in central Montana  

Science.gov (United States)

The effects of land management on groundwater chemistry are often poorly understood due to uncertainties in the connection between soil-vadose transport and groundwater recharge. In the Judith River Watershed of central Montana, decades of elevated and increasing groundwater nitrate may reflect both grassland soil organic matter mineralization upon cultivation and increasing N fertilizer use over time. Landform development and age are key to this connection because they determine aquifer character: Alluvial fans and strath terraces formed over the last two million years host shallow unconfined aquifers that are vulnerable to leaching in our study area, and are cultivated primarily for cereals, without irrigation. Solute and isotopic data from soils, well waters and emergent streams on characteristic landforms suggest that landform type and age, and the associated soil and vadose stratigraphy, are key determinants of hydrologic connection between soils and groundwater. We combine these data with conceptual models for nitrate leaching and groundwater flow to argue that solutes enter groundwater by dispersed recharge, as a function of seasonally rising water tables or increased infiltration that transports accumulated solutes from the soil-vadose zone. In leaching hot spots where fine textured soils are shallow to gravel, land management interacts with groundwater most intimately. Based on point measurements, we interpret larger scale effects of leaching using aerial imagery and satellite data.

Ewing, S. A.; Sigler, W.; Weissmann, G. S.

2012-12-01

368

Seasonal variation, chemical behavior and kinetics of uranium in an unconfined groundwater system  

International Nuclear Information System (INIS)

The seasonal changes in the concentration of uranium in an unconfined groundwater system in Cyprus have been investigated and compared to corresponding changes of boron and salinity, to better understand the chemical behavior of uranium in the respective system. Uranium concentration measurements were performed by alpha spectroscopy after selective pre-concentration, whereas boron concentration analysis and electrical conductivity measurements were carried out by photometry using azomethine-H and an electrical conductivity electrode, respectively. The experimental data show that seasonal variations are mainly related to rainwater infiltration and the specific chemical behavior of a species. Increased levels of uranium and boron in natural water systems are attributed to the increased stability of the uranium(VI)-carbonato complexes and the boric acid, which are in natural waters the predominant chemical species for uranium and boron, respectively. Dilution/dissolution processes govern the seasonal concentration changes of uranium and boron in a groundwater system, however redox-reactions resulting in the reduction of U(VI) to U(IV) affect significantly the concentration of uranium in the respective system, particularly under suboxic conditions. (author)

2014-01-01

369

Comparison of reach-scale morphologic adjustment in confined and unconfined alluvial mountain rivers, Olympic Peninsula, Washington  

Science.gov (United States)

Over human time scales (10-1 - 102 yr), alluvial mountain rivers respond to changes in sediment input and discharge through adjustments in reach-scale morphology (width, depth, grain size, and, to some degree, slope). Channel confinement (valley-width relative to the bankfull channel width) in these systems can strongly influence the magnitude of channel response. We compared channel responsiveness to flood events (50-100 yr) within the last 5 years in unconfined and confined valley segments on the Olympic Peninsula, western Washington. Field measurements of cross-sectional averaged width and depth in 20 confined and 20 unconfined valleys are compared to the bankfull dimensions predicted from established downstream hydraulic geometry relationships for the region. We expect that measured bankfull geometry of confined reaches will be significantly greater than the predicted bankfull dimensions, which would suggest that the morphology of confined channels is more responsive to flood events. In unconfined channels floodplains are large enough to disperse over-bank flows, which can limit the effect of peak discharges on channel morphology, whereas confined channels are forced to disperse the extra energy exerted by peak flows into increased shear stress along their bed and banks. Results from this study can aid modeling efforts to predict future changes in channel geometry and aquatic habitat in response to climate change or land use at the basin scale.

Micheletty, P. D.; Goode, J.; Pierce, J. L.; Buffington, J. M.

2011-12-01

370

Variação da densidade aparente e resistência à compressão paralela às fibras em função da intensidade de desbaste, adubação e posição radial em Eucalyptus grandis hill ex-maiden Variation of the specific gravity mass and the compression strength of the thinning intensity, fertilization and the radial position in Eucalyptus grandis hill ex-maiden  

Directory of Open Access Journals (Sweden)

Full Text Available O Eucalyptus grandis destaca-se pela produtividade e qualidade de sua madeira. O manejo florestal ideal das árvores em que se obtém maior proporção de madeira e melhor qualidade é uma das questões a serem consideradas nas pesquisas de E. grandis. Este trabalho teve como objetivo estudar a variação da densidade aparente e da resistência à compressão paralela às fibras em função da intensidade de desbaste, adubação e classe de diâmetro, na posição radial nas árvores de uma população de E. grandis de 21 anos de idade, manejada pelo sistema de desbastes seletivos com aplicação de fertilizantes na época do início dos desbastes, ou seja, aos 5 anos. Os fatores utilizados foram: três intensidades de desbastes seletivos (37, 50 e 75%, presença ou ausência de fertilizantes, três classes de diâmetro e cinco posições radiais. As influências dos fatores e de suas combinações foram avaliadas na densidade aparente e na resistência à compressão da madeira. A densidade aparente da madeira e a resistência à compressão foram influenciadas pelos fatores: adubo e classe de diâmetro em quase todas as posições radiais aumentaram no sentido da medula para a casca. Observou-se relação positiva entre densidade aparente, resistência à compressão e posição radial.The Eucalyptu grandis stands apart for its productivity and quality wood. The ideal forest management where a greater wood ratio and better quality are obtained is one of the questions to be considered in the research of the E. grandis. The present work had as its general objective the study of the variation of the specific gravity and the resistance to the compression as a function of the thinning intensity, fertilization and diameter classes in the radial position in trees of a 21-year old population of E. grandis, managed under the system of selective thinning, with the application of fertilizaers. The factors used in this study were: three intensities of selective thinning (37, 50 and 75%, presence or absence of fertilizers, three diameter classes and five radial positions. The influences of the factors and of their combinations were evaluated regarding specific gravity and compression strength. The specific gravity and compression strength of the wood were influenced by factors such as fertilizer and diameter class in almost all radial positions, increasing significantly from the pith to bark. A good positive relationship was found to exist among the specific mass, compression strength and radial position.

Israel Luiz de Lima

2010-06-01

371

Variação da densidade aparente e resistência à compressão paralela às fibras em função da intensidade de desbaste, adubação e posição radial em Eucalyptus grandis hill ex-maiden / Variation of the specific gravity mass and the compression strength of the thinning intensity, fertilization and the radial position in Eucalyptus grandis hill ex-maiden  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O Eucalyptus grandis destaca-se pela produtividade e qualidade de sua madeira. O manejo florestal ideal das árvores em que se obtém maior proporção de madeira e melhor qualidade é uma das questões a serem consideradas nas pesquisas de E. grandis. Este trabalho teve como objetivo estudar a variação d [...] a densidade aparente e da resistência à compressão paralela às fibras em função da intensidade de desbaste, adubação e classe de diâmetro, na posição radial nas árvores de uma população de E. grandis de 21 anos de idade, manejada pelo sistema de desbastes seletivos com aplicação de fertilizantes na época do início dos desbastes, ou seja, aos 5 anos. Os fatores utilizados foram: três intensidades de desbastes seletivos (37, 50 e 75%), presença ou ausência de fertilizantes, três classes de diâmetro e cinco posições radiais. As influências dos fatores e de suas combinações foram avaliadas na densidade aparente e na resistência à compressão da madeira. A densidade aparente da madeira e a resistência à compressão foram influenciadas pelos fatores: adubo e classe de diâmetro em quase todas as posições radiais aumentaram no sentido da medula para a casca. Observou-se relação positiva entre densidade aparente, resistência à compressão e posição radial. Abstract in english The Eucalyptu grandis stands apart for its productivity and quality wood. The ideal forest management where a greater wood ratio and better quality are obtained is one of the questions to be considered in the research of the E. grandis. The present work had as its general objective the study of the [...] variation of the specific gravity and the resistance to the compression as a function of the thinning intensity, fertilization and diameter classes in the radial position in trees of a 21-year old population of E. grandis, managed under the system of selective thinning, with the application of fertilizaers. The factors used in this study were: three intensities of selective thinning (37, 50 and 75%), presence or absence of fertilizers, three diameter classes and five radial positions. The influences of the factors and of their combinations were evaluated regarding specific gravity and compression strength. The specific gravity and compression strength of the wood were influenced by factors such as fertilizer and diameter class in almost all radial positions, increasing significantly from the pith to bark. A good positive relationship was found to exist among the specific mass, compression strength and radial position.

Lima, Israel Luiz de; Garcia, José Nivaldo.

372

Compression Enhanced Shear Yield Stress of Electrorheological Fluid  

International Nuclear Information System (INIS)

Shear tests of an electrorheological fluid with pre-applied electric field and compression along the field direction are carried out. The results show that pre-compressions can increase the shear yield stress up to ten times. Under the same external electric field strength, a higher compressive strain corresponds to a larger shear yield stress enhancement but with slight current density decrease, which shows that the particle interaction potentials are not increased by compressions but the compression-induced chain aggregation dominates the shear yield stress improvement. This pre-compression technique might be useful for developing high performance flexible ER or magnetorheological couplings

2009-04-01