Comparison of tensile strength values of rocks determined by point load and direct tension tests

1997 ◽  
Vol 30 (1) ◽  
pp. 65-72 ◽  
Author(s):  
C. Butenuth
Keyword(s):  
Tensile Strength ◽  
Point Load ◽  
Direct Tension ◽  
Tension Tests

Tensile strength of sands treated with microbially induced carbonate precipitation

2020 ◽  
Vol 57 (10) ◽  
pp. 1611-1616 ◽  
Author(s):  
Ashkan Nafisi ◽  
Douglas Mocelin ◽  
Brina M. Montoya ◽  
Shane Underwood
Keyword(s):  
Tensile Strength ◽  
Large Earthquake ◽  
Carbonate Precipitation ◽  
Direct Tension ◽  
Sem Images ◽  
Cemented Soil ◽  
Tension Tests ◽  
Deformational Behavior ◽  
Microbially Induced Carbonate Precipitation ◽  
Sand Type

During large earthquake events where bending moments within soil cements are induced, the tensile strength of cemented soil may govern the deformational behavior of improved ground. Several studies have been conducted to assess the tensile strength of artificially cemented sands that use Portland cement or gypsum; however, the tensile strength of microbially induced carbonate precipitation (MICP)-treated sands with various particle sizes measured through direct tension tests has not been evaluated. MICP is a biomediated improvement technique that binds soil particles through carbonate precipitation. In this study, the tensile strength of nine specimens were measured by conducting direct tension tests. Three types of sand (coarse, medium, and fine) were cemented to reach a heavy level of cementation (e.g., shear wave velocity of ∼900 m/s or higher). The results show that the tensile strength varies between 210 and 710 kPa depending on sand type and mass of carbonate. Unconfined compressive strength (UCS) tests were performed for each sand type to assess the ratio between tensile strength and UCS in MICP-treated sands. Scanning electron microscopy (SEM) images and surface energy measurements were used to determine the predominant failure mode at particle contacts under tensile loading condition.

scholarly journals The Influence of Loading Rate on Direct and Indirect Tensile Strengths: Laboratory and Numerical Methods

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Jie Liu ◽  
Gangyuan Jiang ◽  
Taoying Liu ◽  
Qiao Liang
Keyword(s):  
Tensile Strength ◽  
Tensile Stress ◽  
Crack Propagation ◽  
Large Scale ◽  
Loading Rate ◽  
Peak Stress ◽  
Direct Tension ◽  
Tension Tests ◽  
Indirect Tension ◽  
Indirect Tensile

To investigate different responses of direct and indirect tensile strengths to loading rate, direct and indirect tension tests were performed on sandstone, rust stone, and granite specimens. Typical load curves indicate that a peak tensile stress frequently appears before the second peak stress, used to calculate the tensile strength in indirect tension tests. As expected, increase in the loading rate increases the tensile strength. In addition, the calculated tensile strengths of the indirect tension tests are frequently higher. Interestingly, the increase ratio of the tensile strength with the increase in the loading rate in indirect tension tests is higher. To verify the above results, crack propagation and stress evolution in direct and indirect tension tests were dynamically monitored using PFC 3D. For direct tension tests, specimens fail at the peak tension point, corresponding to the tensile strength. However, for indirect tension tests, minor cracks, composing of continuous microcracks, form before the peak stress and accompany with the decreased slope of the compression curve. At the peak point, tensile stresses significantly concentrate at the crack tips and further cause large-scale crack propagation. In addition, the initiation stress instead of the peak tensile stress is closer to the tensile strength, obtained from the direct tests for the same loading rate.

MECHANICAL STRENGTH OF SEALED-CURED NEAT CEMENT-PASTE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
S. Walker ◽  
W. Choi ◽  
M. Picornell ◽  
R. Mohan ◽  
S. Hamoush
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Cement Paste ◽  
Concrete Strength ◽  
Curing Time ◽  
Portland Cement Concrete ◽  
Direct Tension ◽  
Tension Tests ◽  
Water To Cement Ratio ◽  
Program Show

The strength of Portland cement concrete is dependent on the strength of the cement paste binding the aggregates together. An understanding of the cement paste is the first step to assess the concrete strength. To this end, a program for strength testing of cement paste was implemented for water to cement ratios of 0.35 and 0.40. The compressive strength was evaluated using two inch cubes and four inch diameter cylinders; while the tensile strength evaluation was based on flexure and direct tension tests. All the specimens were cured in the mold the first day, followed by curing in sealed vacuum bags for the remaining of the time. The total curing time ranged from three, seven, fourteen and twenty-eight days. Three replicate specimens were prepared, cured, and tested for each combination of water to cement ratio, type of specimen, and time of curing. The results of the testing program show that while the compressive strength increases for increasing curing time, the tensile strength shows a consistent decline. These results indicate that the sealed curing forced that further hydration caused “self-desiccation” of the CSH, inducing new cracks or extension of existing cracks that would be responsible for the loss of tensile strength.

Experimental Investigation on Fracture and Tensile Characteristics of Micro-Surfacing Containing Crumb Rubber

2008 ◽  
Vol 385-387 ◽  
pp. 489-492 ◽  
Author(s):  
Zheng Chen ◽  
Shao Peng Wu ◽  
Tao Zhang ◽  
Ling Pang
Keyword(s):  
Tensile Strength ◽  
Crumb Rubber ◽  
Point Load ◽  
Indirect Tensile Strength ◽  
Asphalt Emulsion ◽  
Mean Values ◽  
Modified Asphalt ◽  
Tension Tests ◽  
Indirect Tension ◽  
Indirect Tensile

The major objective of this research was to evaluate the tensile and fracture properties of micro-surfacing, which as a preventive maintenance surface treatment on asphalt pavement, that formed the basis for the ISSA recommendation of an optimum micro-surfacing design incorporating crumb rubber. The research involved a full-factorial experiment with different rubber contents (0, 2 and 5%) and different polymer modified asphalt emulsion contents ranged from 10 to 13% by total weight of crushed aggregate in micro-surfacing. Fracture and indirect tension tests were performed on micro-surfacing beams and Marshall test samples, respectively, at two different test temperatures of 25 and -10°C. The variables studied were indirect tensile strength, peak center-point load carried, and load-point displacement. The results show that higher mean values of indirect tensile strength were obtained corresponding to the highest modified asphalt emulsion content (13%), irrespective of rubber contents, particularly at lower temperatures. A statistical analysis of the test results reveals that there are no significant differences among the means of most of the variables studied corresponding to different rubber contents. However, the differences are significant for different asphalt emulsion contents.

Watertightness, cracking resistance, and self-healing of asphalt concrete used as a water barrier in dams

2013 ◽  
Vol 50 (3) ◽  
pp. 275-287 ◽  
Author(s):  
Yingbo Zhang ◽  
Kaare Höeg ◽  
Weibiao Wang ◽  
Yue Zhu
Keyword(s):  
Asphalt Concrete ◽  
Leakage Rate ◽  
Strain Rates ◽  
Self Healing ◽  
Test Results ◽  
Direct Tension ◽  
Coefficient Of Permeability ◽  
Tension Tests ◽  
Laboratory Test Results ◽  
Cracked Specimens

The coefficient of permeability of hydraulic asphalt concrete is in the range 10−8–10−10 cm/s. Laboratory test results show that triaxial specimens in axial compression can undergo axial strains up to 18% without any significant increase in permeability until approaching the compressive strength. For temperatures between 5 and 20 °C and strain rates between 2 × 10−3%/s and 5 × 10−3%/s, conventional hydraulic asphalt concrete can tolerate 1%–3% tensile strains before cracking in direct tension tests and strains up to 3%–4% in bending. At 20 °C the tensile and bending strains at cracking are 2–4 times higher than those at 0 °C, and at −20 °C they are approximately 0.2% and 0.8%, respectively. Asphalt concrete possesses pronounced crack self-healing properties. In the experiments, the crack leakage rate dropped 1–4 orders of magnitude within a few hours and the cracked specimens regained 55% of the intact tensile strength after only 1 day of self-healing. In summary, the comprehensive series of laboratory tests documents that asphalt concrete has characteristics that make the material extremely well suited for use in impervious barriers in dams, and the test results reported herein can be of great use in barrier design.

scholarly journals IX. On the existence of an element of strength in beams subjected to transverse strain, arising from the lateral action of the fibres or particles on each other, and named by the author the 'resistance of flexture.’

1855 ◽  
Vol 145 ◽  
pp. 225-242
Keyword(s):  
Tensile Strength ◽  
Cast Iron ◽  
Neutral Axis ◽  
Direct Compression ◽  
Transverse Strain ◽  
Direct Tension ◽  
Direct Tensile ◽  
Direct Tensile Strength

It has been long known, that under the existing theory of beams, which recognizes only two elements of strength, namely, the resistances to direct compression and extension, the strength of a bar of cast iron subjected to transverse strain cannot be reconciled with the results obtained from experiments on direct tension, if the neutral axis is in the centre of the bar. The experiments made both on the transverse and on the direct tensile strength of this material have been so numerous and so carefully conducted, as to admit of no doubt of their accuracy; and it results from them, either that the neutral axis must be at, or above, the top of the beam, or there must be some other cause for the strength exhibited by the beam when subjected to transverse strain.

Assessment of Direct Tension Tests on Compacted Sand-Clay Mixtures

2019 ◽  
Vol 31 (10) ◽  
pp. 04019236
Author(s):  
Yu-Syuan Jhuo ◽  
Yu Guan ◽  
Louis Ge ◽  
Zhao Xia ◽  
Xin Kang
Keyword(s):  
Direct Tension ◽  
Tension Tests

scholarly journals Determination of Direct Tensile Strength Values of Rock Materials by a New Test Method of Drilled Disc Tension

2019 ◽  
Author(s):  
Eren Komurlu ◽  
Serhat Demir
Keyword(s):  
Tensile Strength ◽  
Experimental Studies ◽  
Test Method ◽  
Uniaxial Tensile ◽  
Direct Tension ◽  
Rock Materials ◽  
Uniaxial Tensile Stress ◽  
Direct Tensile ◽  
Drill Holes ◽  
Direct Tensile Strength

Use of drilled disc specimens was investigated with both numerical and experimental studies to determine direct tensile strengths of rock materials. A new loading apparatus with rods to insert into the drill holes of discs has been designed and manufactured to supply tension by using the compression test presses. In addition to the use of popular compressive presses for direct tension, elimination of the gluing in the standard direct tensile strength test method is a significant advantage to make possible both hard and soft rocks to be tested. The Brazilian test discs with the diameter of NX size and length to diameter ratio of 0.5 were used in tests. Different loading apparatus designs were analyzed and ideal angle of contact between rock and the loading rods was assessed to be 50° within various choices investigated in this study. The drilled discs were determined to fail due to the crack initiation under the condition of uniaxial tensile stress distribution at sidewalls of the hole. In addition to the drilled disc tension test, standard direct tensile strength tests were also carried out to take as reference and compare the results obtained from different methods. According to the results of both numerical and experimental studies, an equation was suggested to determine uniaxial tensile strengths of drilled disc specimens with 20 mm hole diameter and the contact angle of 50°.

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