• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.246-253
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• 2003

Although concrete members are not normally designed to resist direct tension, the knowledge of tensile strength is of value in estimating the cracking load. In general, there are three types of test method for tensile strength ; direct tension test, flexural tension test, and splitting tension test. Though direct tensile strength represents the real tensile strength of concrete, direct tension tests are seldom carried out, mainly because it is very difficult to applicate a pure tension force. The purpose of this paper is to investigate the test methods, effect of aspect ratio, and the size effect on the direct tensile strength. Direct tension test, using bonded end plates, follows RILEM and U.S.Bureau of Reclamation. And other test methods follow ASTM provisions. Four kinds of aspect ratio and two kinds of size effect are tested. Same variables are tested by direct tension test and splitting tension test for comparison between the two test methods. Test results show that direct tensile strength of concrete is more affected by aspect ratio and size than other kinds of strength.

• International Journal of Concrete Structures and Materials
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• v.5 no.2
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• pp.87-96
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• 2011

Many studies have been performed on steel fiber-reinforced normal/high-strength concrete (SFRC, SFRHC) for years, which is to improve some of the weak material properties of concrete. Most of equations for material strengths of SFRHC, however, were proposed based on relatively limited test results. In this research, therefore, the material test results of SFR(H)C were extensively collected from literature, and material tests have conducted on SFR(H)C; compressive strength tests, splitting tensile tests, and modulus of rupture tests. Based on the extensive test data obtained from previous studies and this research, a database of SFR(H)C material strengths has been established, and improved equations for material strengths of SFR(H)C were also proposed. Test results showed that both the splitting tensile strength and the modulus of rupture of SFR(H)C increased as the volume fraction of steel fiber increased, while the effect of the steel fiber volume fraction on the compressive strength of SFR(H)C were not clearly observed. The proposed equations for the splitting tensile strength and the modulus of rupture of SFR(H)C showed better results than the previous equations examined in this study in terms of not only accuracy but also safety/reliability.

• Computers and Concrete
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• v.18 no.1
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• pp.39-51
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• 2016

This paper considers the tensile strength of concrete samples in direct, CTT, modified tension, splitting and ring tests using both of the experimental tests and numerical simulation (particle flow code 2D). It determined that which one of indirect tensile strength is close to direct tensile strength. Initially calibration of PFC was undertaken with respect to the data obtained from Brazilian laboratory tests to ensure the conformity of the simulated numerical models response. Furthermore, validation of the simulated models in four introduced tests was also cross checked with the results from experimental tests. By using numerical testing, the failure process was visually observed and failure patterns were watched to be reasonable in accordance with experimental results. Discrete element simulations demonstrated that the macro fractures in models are caused by microscopic tensile breakages on large numbers of bonded discs. Tensile strength of concrete in direct test was less than other tests results. Tensile strength resulted from modified tension test was close to direct test results. So modified tension test can be a proper test for determination of tensile strength of concrete in absence of direct test. Other advantages shown by modified tension tests are: (1) sample preparation is easy and (2) the use of a simple conventional compression press controlled by displacement compared with complicate device in other tests.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.206-215
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• 2017

An experimental program was carried out to investigate the mechanical properties of high-strength concrete. High-strength concrete with compressive strengths of 80 to 120 MPa was tested. Test results are presented regarding effect of water-binder ratio on compressive strength and compressive strength gain. In addition, the effect of curing methods on compressive strength, elastic modulus, splitting tensile strength, and modulus of rupture is investigated. Test results of elastic modulus, splitting tensile strength, and modulus of rupture are compared with predictions from the current design recommendations. Predictions of elastic modulus by using KCI recommendation has good agreement with test results. However, predictions of modulus of rupture by using KCI recommendation underestimate the test results. ACI 363R recommendations predict well test results of splitting tensile strength and modulus of rupture. ACI 363R recommendations for predicting splitting tensile strength and modulus of rupture can be used for high-strength concrete with compressive strengths up to 120 MPa.

• Computers and Concrete
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• v.3 no.6
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• pp.389-400
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• 2006

This paper presents the investigations towards developing a better understanding on the contribution of steel fibers on the tensile strength of high-performance fiber reinforced concrete (HPFRC). An extensive experimentation was carried out with w/cm ratios ranging from 0.25 to 0.40 and fiber content ranging from zero to 1.5 percent with an aspect ratio of 80. For 32 concrete mixes, flexural and splitting tensile strengths were determined at 28 days. The influence of fiber content in terms of fiber reinforcing index on the flexural and splitting tensile strengths of HPFRC is presented. Based on the test results, mathematical models were developed using statistical methods to predict 28-day flexural and splitting tensile strengths of HPFRC for a wide range of w/cm ratios. The expressions, being developed with strength ratios and not with absolute values of strengths and are applicable to wide range of w/cm ratio and different sizes/shapes of specimens. Relationship between flexural and splitting tensile strengths has been developed using regression analysis and absolute variation of strength values obtained was within 3.85 percent. To examine the validity of the proposed model, the experimental results of previous researchers were compared with the values predicted by the model.

• Journal of the Korean Geotechnical Society
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• v.31 no.3
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• pp.5-16
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• 2015

The characteristics of tensile strength of fiber-reinforced grouting (cement paste) injected into rocks or soils were studied. A tensile strength of such materials utilized in civil engineering has been commonly tested by an indirect splitting tensile test (Brazilian test). In this study, a direct tensile testing method was developed with built-in cylinder inside a cylindrical specimen with 15 cm in diameter and 30 cm in height. The testing specimen was prepared with 0%, 0.5%, or 1% (by weight) of a PVA or steel fiber reinforced mortar. A specimen with 5 cm in diameter and 10 cm in height was also prepared and tested for the splitting tensile test. Each specimen was air cured for 7 days or 28 days before testing. The tensile strength of built-in cylinder test showed 96%-290% higher than that of splitting tensile test. The 3D finite element analyses on these tensile tests showed that the tensile strength from built-in cylinder test had was 3 times higher than that of splitting tensile test. It is similar to experimental result. As an amount of fiber increased from 0% to 1%, its tensile strength increased by 119%-190% or 23%-131% for 7 days or 28 days-cured specimens, respectively. As a curing period increased from 7 days to 28 days, its strength decreased. Most specimens reinforced with PVA fiber showed tensile strength 14%-38% higher than that of steel fiber reinforced specimens.

• Advances in concrete construction
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• v.13 no.3
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• pp.265-279
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• 2022

The roughness of substrate concrete interfaces before new concrete placement has a major effect on the interface bond behaviour. However, there are challenges associated with the consistency of the final roughness interface prepared using conventional roughness preparation methods which influences the interface bond performance. In this study, five quantitative interface roughness textures with different roughness tooth angles, depths, and tooth distribution were created to ensure consistency of interface roughness and to evaluate the bond behaviour at a precast and new concrete interface using the splitting tensile test, slant shear test, and double-shear test. In addition, smooth interface specimens and two separate the pitting interface roughness were also utilized. Obtained results indicate that the quantitative roughness has a very limited effect on the interface tensile bond strength if no extra micro-roughness or bonding agent is added at the interface. The roughness method however causes enhanced shear bond strength at the interface. Increased tooth depth improved both the tensile and shear bond strength of the interfaces, while the tooth distribution mainly influenced the shear bond strength. Major failure modes of the test specimens include interface failure, splitting cracks, and sliding failure, and are influenced by the tooth depth and tooth distribution. Furthermore, the interface properties were obtained and presented while a comparison between the different testing methods, in terms of bond strength, was performed.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.423-426
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• 2001

In this paper a large scale direct tension test of plain concrete is represented. Two independently controlled actuators were used to ensure a homogeneous tensile field and to avoid secondary flexural stresses. Fracture energies evaluated by a classical prediction equation and this test are compared. The result indicated that the classical prediction equation is not adequate to predict the fracture energy of large sized specimens. From this test, it was determined that the fracture energy obtained from large scale direct tension tests is significantly higher than the one obtained in wedge splitting tests on laboratory sized specimens. But the tensile strength was about half the value determined from splitting tensile strength test with cylindrical specimens.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.155-161
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• 2003

This paper presents experimental and analytical results of glass fiber-reinforced concrete (GFRC) and polypropylene fiber-reinforced concrete (PERC) to investigate the relationship between tensile strength and compressive strength based on the split cylinder test (ASTM C496) and compressive strength test (ASTM C39). Experimental studies were performed on cylinder specimens having 150 mm in diameter an 300 mm in height with two different fiber contents (1.0 and 1.5％ by volume fraction) at ages of 7, 28 and 90 days. A total of 90 cylinder specimens were tested including specimens made of the plain concrete. The experimental data have been used to obtain the relationship between tensile strength and compressive strength. A representative equation is proposed for the relationship between tensile strength and compressive strength of fiber-reinforced concrete (FRC) including glass and polypropylene fibers. There is a good agreement between the average experimental results and those calculated values from the proposed equation.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.205-213
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• 2007

Strength relationships are presented through experimental data from the concrete strength tests in this study. Various strength tests such as the compressive, flexural, and splitting tensile strength and the modulus of elasticity are included. An experimental work was performed to determine the various strength characteristics for various mix designs. Three different coarse aggregates such as granite, limestone, sandstone were used and included were fine aggregates such as natural sand, washed sand and crushed sand. Also included was cement amount as experimental variable. It was confirmed that each strength value with respect to curing time is to follow a typical strength development curve. With this somewhat reliable test results various strength relationships such as flexural strength-compressive strength, splitting tensile strength-compressive strength, modulus of elasticity-compressive strength, splitting tensile strength-flexural strength were analyzed through statistics. Experimental data were well fitted to the 0.5-power relationship of flexural strength and compressive strength which has been commonly accepted. The splitting tensile strength is expected to be best in the linear relationship from the flexural strength data. Finally splitting tensile strength was found to be proportional to the 0.87 power of the cylindrical compressive strength.