scholarly journals Details about unconfined compression tests and diametral compression tests for tensile strength determination

Geotecnia ◽  
2016 ◽  
Vol 136 ◽  
pp. 127-142
Author(s):  
Saul Barbosa Guedes ◽  
◽  
<br>Roberto Quental Coutinho ◽  
<br>António Viana da Fonseca ◽  
◽  
...  
2020 ◽  
Vol 195 ◽  
pp. 03008
Author(s):  
Carmen Covadonga Garcia-Fernandez ◽  
Rafaela Cardoso ◽  
Martina Inmaculada Alvarez-Fernandez ◽  
Celestino Gonzalez-Nicieza

Cracking due to desiccation can compromise the behaviour of earth structures built with compacted clayey soils by promoting water access and consequent volume changes on further wetting. Tensile strength therefore is important to be considered when studying the behaviour of such structures, and in particular its dependence on the degree of saturation or water content. The influence of water content in tensile behaviour of compacted marls was investigated by performing diametral compression tests (Brazilian splitting tests), where axial deformations were measured besides strength. The samples were prepared by compaction at optimum point using standard compaction energy (optimum water content 16%) and then dried by vapour equilibrium to reach water contents between 5% and 16%. The correspondence between water content and suction was done by using the drying branch of the water retention curve, measured using WP4 equipment (Water Dewpoint Potentiometer). Good relationships were found between tensile strength and the water content (and suction). In addition, the study was completed with the analysis of other parameters such as the semi-contact angle created in the loaded area and the stiffness of the material, which also showed changes with water content.


1995 ◽  
Vol 32 (1) ◽  
pp. 166-171 ◽  
Author(s):  
B.M. Das ◽  
S.C. Yen ◽  
R.N. Dass

Tensile stress – tensile strain relationships for lightly cemented sand specimens obtained by conducting Brazilian tensile strength tests have been presented. The tensile strain measurement was done by using an optical image analysis technique. In addition to the tensile strength tests, some unconfined compression tests on sand specimens with varying cement contents were also performed. Based on the results of the above tests, a nondimensional tensile stress – tensile strain relationship has been presented. Also the variation of the tensile and compressive strength and strain ratios with varying cement contents have been discussed. Key words : lightly cemented sand, optical image analysis, tensile strain, tensile strength, unconfined compression strength.


1970 ◽  
Vol 7 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roland Pusch

A series of unconfined compression tests has been made on a marine, quick clay and small specimens were extracted for microstructural investigation. The natural microstructural pattern was characterized by a network of small aggregates connected by links of particles. The links broke down successively at increasing shear deformation and formed domain-like groups of particles. In the macroscopic shear zone the shear forces tended to orient and deform the aggregates.The aggregates behaved as rigid bodies to a certain stress level during the shear process. The concept of residual strength may correspond to the state where the majority of the links have been broken while the aggregates are still intact.


1970 ◽  
Vol 12 (1) ◽  
pp. 9-24
Author(s):  
Kazuo NAGAI ◽  
Masayoshi OHASHI ◽  
Hiroyoshi HABU ◽  
Masahiro UEMURA ◽  
Fujio KORENAGA ◽  
...  

Author(s):  
Ömür Çimen ◽  
Mehmet Saltan ◽  
S. Nilay Keskin

AbstractHigh-plasticity clayey subgrade, which is unsuitable for road construction, may sometimes occur along highway routes. In such cases, engineers need to change the route of a highway project, resulting in an increase in road length and project costs. In this study, waste pumice was examined for stabilization of high-plasticity clayey subgrade, which is inappropriate for road construction. For this purpose, the physical and index properties of clay and pumice were determined. Then, the pumice was mixed with high plasticity clay at different ratios by weight. By performing standard Proctor compaction tests on the mixtures, the effects of adding pumice on compaction were also studied. Unconfined compression tests and California bearing ratio (CBR) tests were performed on all pumice-clay mixtures, and the test results and the CBR ratios were compared for each sample, respectively. The results showed that pumice stabilization improved the mechanical properties and reduced the swelling potential of high plasticity clayey subgrade.


2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Ali Ateş

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


2018 ◽  
Vol 928 ◽  
pp. 263-268 ◽  
Author(s):  
Anuchit Uchaipichat

The soil-cement columns are generally installed and cured in the soft clay layers under confining pressure. The strength of the soil-cement columns may be influenced by confining pressure during curing period. In this study, the main objective was to study the influence of curing pressure on unconfined compressive strength of cemented clay. A series of unconfined compression tests was performed on a cement admixed clay sample cured under pressure values of 0 kPa (atmospheric pressure), 25kPa, 50kPa and 100 kPa using a typical unconfined compression equipment. The test samples with values of cement content of 0.5, 1.0 and 2.0 percent were cured for 28 days.The stress-strain curves obtained from all tests show a peak value of stress. The unconfined compressive strength or peak stress obviously increased with increasing cement content for all curing pressure conditions. It can be observed that the strength of samples gradually increased with curing pressure for cement content of 0.5 percent. For cement contents of 1.0 and 2.0 percent, the strengths of samples cured under pressures of 25 kPa dramatically increased from the strength of samples cured without pressure (0 kPa), however, the strengths of samples for curing pressures of 25, 50 and 100 kPa were not clearly different.


Author(s):  
Sara Fayek ◽  
Xiaolong Xia ◽  
Lin Li ◽  
Xiong Zhang

Triaxial tests are used extensively to evaluate stress-strain behavior for both saturated and unsaturated soils. A literature review indicates that all conventional triaxial test methods measure the relative volume of soil; however, between the initial measurements and the start of the triaxial tests, there are unavoidably disturbances during installation that cause deviation of soil volume from that at the initial condition. Recently image-based methods have been developed to measure the absolute volume of soil specimens. However, these methods still have a major limitation in their inability to determine top and bottom boundaries between the soil specimen, and the top and bottom caps. This paper proposes a photogrammetry-based method to overcome this limitation by developing a mathematically rigorous technique to determine the upper and lower boundaries of soil specimens during triaxial testing. The photogrammetry technique was used to determine the orientations of the camera, and the shape and location of the acrylic cell. Multiple ray-tracings and least-square optimization techniques were also applied to obtain the coordinates of any point inside the triaxial cell, and thus back-calculate the upper and lower boundaries. With these boundaries and the side surface, a triangular surface mesh was constructed and the specimen volume was then calculated in both unconfined compression tests and triaxial tests. The calculation procedures are presented in detail with validation tests performed on a cylindrical specimen to evaluate the accuracy of the method. Results indicate that the accuracy of the proposed method is up to 0.023% in unconfined compression tests and 0.061% in triaxial tests.


Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 889 ◽  
Author(s):  
Chengdong Xia ◽  
Songtao Lv ◽  
Lingyun You ◽  
Dong Chen ◽  
Yipeng Li ◽  
...  

Although the rutting resistance, fatigue cracking, and the resistance to water and frost are important for the asphalt pavement, the strength of asphalt mixture is also an important factor for the asphalt mixture design. The strength of asphalt mixture is directly associated with the overall performance of asphalt mixture. As a top layer material of asphalt pavement, the strength of asphalt mixture plays an indispensable role in the top structural bearing layer. In the present design system, the strength of asphalt pavement is usually achieved via the laboratory tests. The stress states are usually different for the different laboratory approaches. Even at the same stress level, the laboratory strengths of asphalt mixture obtained are significantly different, which leads to misunderstanding of the asphalt mixtures used in asphalt pavement structure design. The arbitrariness of strength determinations affects the effectiveness of the asphalt pavement structure design in civil engineering. Therefore, in order to overcome the design deviation caused by the randomness of the laboratory strength of asphalt mixtures, in this study, the direct tension, indirect tension, and unconfined compression tests were implemented on the specimens under different loading rates. The strength model of asphalt mixture under different loading modes was established. The relationship between the strength ratio and loading rate of direct tension, indirect tension, and unconfined compression tests was adopted separately. Then, one unified strength model of asphalt mixture with different loading modes was established. The preliminary results show that the proposed unified strength model could be applied to improve the accurate degree of laboratory strength. The effectiveness of laboratory-based asphalt pavement structure design can therefore be promoted.


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