scholarly journals A New Flattened Cylinder Specimen for Direct Tensile Test of Rock

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4157
Author(s):  
Qiuhua Rao ◽  
Zelin Liu ◽  
Chunde Ma ◽  
Wei Yi ◽  
Weibin Xie
Keyword(s):  
Tensile Strength ◽  
Tensile Test ◽  
Cylindrical Specimen ◽  
Image Correlation ◽  
Stress Distributions ◽  
Direct Tension ◽  
Brazilian Disc ◽  
Indirect Tensile ◽  
Direct Tensile ◽  
Direct Tensile Test

In recent decades, researchers have paid more attention to the indirect tensile test than to the direct tensile test (DTT) of rocks, mainly due to difficulties in the alignment and the stress concentration at the end of an intact cylindrical specimen. In this paper, a new flattened cylinder specimen and a clamp device were designed to obtain the true tensile strength of the rock in DTT. Stress distributions of the specimen with different lengths (l) and cutting thicknesses (t) were analyzed, and damage processes of the specimen were monitored by the Digital Image Correlation (DIC), the fractured sections were also scanned. Different mechanical parameters were also obtained by the DTT of the flattened cylinder specimens and the intact cylinder specimens, as well as the Brazilian disc. Research results show that the tensile strength obtained by DTT is smaller than the Brazilian disc and is slightly greater than the intact cylindrical specimen. The flattened cylinder specimen with 0.20 ≤ 2t/D < 0.68 and 0.10 ≤ l/D ≤ 0.20 is recommended to measure the true tensile strength of rock material in DTT. This new shape of the specimen is promising to be extended in the uniaxial or triaxial direct tension test.

scholarly journals Calculation Derivation and Test Verification of Indirect Tensile Strength of Asphalt Pavement Interlayers at Low Temperatures

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6041
Author(s):  
Qian Zhang ◽  
Zhihe Fang ◽  
Yiheng Xu ◽  
Zhao Ma
Keyword(s):  
Tensile Strength ◽  
Tensile Test ◽  
Asphalt Pavement ◽  
Indirect Tensile Strength ◽  
Elastic Theory ◽  
Calculation Formula ◽  
Indirect Tensile Test ◽  
Indirect Tensile ◽  
Direct Tensile ◽  
Direct Tensile Test

When the direct tensile test is adopted to determine the interlayer tensile strength of the asphalt pavements, specimen separation or internal cracking often occurs at the bonding area of the loading head, rather than at the interlaminar bonding interface. In view of the tedious and discrete data of the direct tensile test, this paper attempts to introduce an indirect tensile test to determine the interlayer bond strength of asphalt pavement to solve this problem. However, the indirect tensile test method of a binder lacks the corresponding mechanical theory. This paper deduces the calculation formula of the indirect tensile strength of a binder based on elastic theory. A mechanical model of the test was established with the finite element method. In accordance with the two-dimensional elastic theory and the Flamant solution, an analytical solution of tensile stress in the indirect tensile test is proposed through the stress superposition. On this basis, the calculation formula for the indirect tensile strength of the interlaminar bonding is derived according to Tresca’s law. A low-temperature indirect tensile test was designed and conducted to verify the correctness of the formula. By comparing the results of the indirect tensile test and direct tensile test, it is found that the interlaminar strength of the mixture measured by them is similar, and the dispersion of indirect tensile test results is small. The results show that the indirect tensile test can replace the direct tensile test to evaluate the interlaminar tensile strength.

Comparison of Tensile Strengths with Different Test Methods in Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC)

2009 ◽  
Vol 417-418 ◽  
pp. 649-652 ◽  
Author(s):  
Su Tae Kang ◽  
Jung Jun Park ◽  
Gum Sung Ryu ◽  
Gyung Taek Koh ◽  
Sung Wook Kim
Keyword(s):  
Tensile Strength ◽  
Tensile Test ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Steel Fiber Reinforced Concrete ◽  
Flexural Tensile Strength ◽  
Ultra High Strength Steel ◽  
Direct Tensile ◽  
Direct Tensile Test ◽  
Direct Tensile Strength

Ultra High Strength Steel-Fiber Reinforced Concrete (UHS-SFRC) is characterized by very high compressive and tensile strength that is about 8 times of ordinary concrete, and high ductility owing to the addition of steel fibers. This paper investigates the relationship existing among the direct tensile strength, flexural tensile strength and splitting tensile strength of UHS-SFRC. Differently from ordinary concrete, it is found that the first cracking strengths in UHS-SFRC obtained through direct tensile test and splitting tensile test are similar, while the strength obtained from flexural tensile test is significantly larger than those from other tests. Based on the experimental results, relationships between the direct tensile strength and flexural tensile strength, between the first cracking strengths in direct tensile test and in flexural tensile test, and between the first cracking strength in direct tensile test and the flexural tensile strength are proposed.

Experimental investigation of recycled aggregate effect on the concrete properties

2018 ◽  
Vol 9 (4) ◽  
pp. 560-571
Author(s):  
Hamed Hemmati Pourghashti ◽  
Malek Mohammad Ranjbar ◽  
Rahmat Madandoust
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Tensile Test ◽  
Recycled Concrete ◽  
Test Results ◽  
Content Type ◽  
Treatment Conditions ◽  
Natural Aggregates ◽  
Direct Tensile ◽  
Direct Tensile Test

Purpose The purpose of this paper is to conduct a laboratory investigation on measuring the tensile strength of recycled concrete using a double punch test. Furthermore, one of the main goals of this study is to compare the tensile and compressive strengths of recycled concrete samples. Design/methodology/approach Recycled concrete samples were made with variables such as aggregate type (natural stone and aggregate recycled concrete), different water-to-cement ratios and different treatment conditions in the first stage. In the next stage, the double punch test was performed on them, and finally the results obtained from experiments were analyzed and investigated. Findings According to the above tests, it was concluded that: first, according to the laboratory results, the strength of concrete containing recycled aggregates becomes closer to the strength of concrete containing natural aggregates whenever the water-to-cement ratio is higher. Second, upon investigating the treatment conditions, it was observed that the treatment had a greater effect on the strength of the recycled concrete. However, this effect was less tangible in tensile strength. Third, upon investigating the results of tensile strength, it can be said that the Barcelona test results were closer to the direct tensile test results compared to the Brazilian test results. This indicates the higher viability of Barcelona’s test results. Fourth, the results obtained from the Barcelona tensile test for recycled concrete were closer to the results of the direct tensile test compared to the concrete containing natural aggregates, which suggests that the Barcelona test is more suitable as a tensile test for recycled concrete. Fifth, the effects of various factors on tensile strength were somewhat less compared to the compressive strength, although very close. Sixth, the relationships provided by the regulation for concrete tensile strength on compressive strength were highly inconsistent with the results obtained from the direct tensile test, for which the consistency was higher for concrete containing natural aggregates compared to recycled concrete. Seventh, the dispersion of results obtained from tensile tests was higher for recycled concrete compared to concrete containing natural aggregates, but lesser of this dispersion was observed in the compressive strength. Originality/value According to the laboratory results, the strength of concrete containing recycled aggregates becomes closer to the strength of concrete containing natural aggregates whenever the water-to-cement ratio is higher. Upon investigating the treatment conditions, it was observed that the treatment had a greater effect on the strength of the recycled concrete. However, this effect was less tangible in tensile strength. On the basis on the results of the tensile strength, it can be said that the Barcelona test results were closer to the results of the direct tensile test compared to those of the Brazilian test. This indicates the higher viability of Barcelona’s test results. The results obtained from the Barcelona tensile test for recycled concrete were closer to the results of direct tensile test compared to the concrete containing natural aggregates, which suggests that the Barcelona test is more suitable as a tensile test for recycled concrete. The effects of various factors on tensile strength were somewhat less compared to the compressive strength, although very close. The relationships provided by the regulation for concrete tensile strength on compressive strength were highly inconsistent with the results obtained from the direct tensile test, for which the consistency was higher for concrete containing natural aggregate compared to recycled concrete. The dispersion of results obtained from tensile tests was higher for recycled concrete compared to concrete containing natural aggregate, but lesser of this dispersion was observed in the compressive strength.

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.

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