• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.173-178
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• 2000

New prediction model is investigated estimating splitting tensile strength and modulus of elasticity with curing temperature and aging. New prediction model is based on the model which was proposed to predict compressive strength, and splitting tensile strength and modulus of elasticity calculated by this model are compared with experimental values. New prediction model well estimated splittinge tensile strength and elastic modulus as well as compressive strength.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.206-211
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• 2015

Recently, for UHPC (Ulta High Performance Concrete) which is researched actively, as the tensile strength is absolutely influenced on the content of steel fiber, in this paper, experiments of compressive strength, elasticity modulus and tensile strength were performed according to compressive strength and content of steel fiber as variables. By the test results, compressive strength, elasticity modulus and tensile strength are proportioned and have a good correlation and according to content of steel fiber, compressive and tensile strength are also proportioned and have a good correlation. In case of elasticity modulus, the difference between test and present design code is not large, so it is possible to adapt to present design code. On the other hand, in case of tensile strength, as there is no specification of present design code, new prediction equation is proposed by using nonlinear regression analysis and the proposed equation have a good correlation to test results.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.4
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• pp.25-32
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• 2005

This study was performed to evaluate the strength properties of polymer concrete using recycled aggre-gate. The compressive strength, splitting tensile strength, flexural strength and pulse velocity of polymer concrete were decreased with increasing the content of recycled aggregate. At the curing age of 7days, the compressive strength was $80.5\~88.3$ MPa, the splitting tensile strength was $9.1\~10.6$ MPa, the flexural strength was $19.2\~21.5$ MPa and the pulse velocity was $3,931\~4,041$ m/s, respectively. Also, the compressive strength, splitting tensile strength, flexural strength and pulse velocity of concrete using recycled fine aggregate were higher than that of the silica sand. Therefore, these recycled aggregate polymer concretes were estimated for high strength concrete without major problem.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.35-42
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• 2000

In paper I, the relationships between compressive strength and splitting tensile strength or modulus of elasticity were proposed. In this paper, new prediction model is investigated from estimating splitting tensile strength and modulus of elasticity with curing temperature and aging without compressive strength. New prediction model is based on the model which was proposed to predict compressive strength, and splitting tensile strength and modulus of elasticity calculated by this model are compared with experimental values of paper I. To evaluate in-situ applicability of the model, strength and modulus of elasticity tested with variable temperatures are estimated by the prediction model. The prediction model reasonably estimates the strength and the modulus of elasticity of type I and V cement concretes tested in paper I and experimental results with variable temperature tested in this paper.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.29-32
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• 2004

An experimental investigation of the behavior of steel cords(SC) and SC and Polyethylene(PE) hybrid fiber reinforced cementitious material under compressive and tensile loading is presented. In this experimental research, the tensile and compressive strength and strain capacity of high performance fiber-reinforced cementitious composites(HPFRCC) were selected using the cylindrical specimens. Uniaxial compressive and tensile tests have also been carried out at varying strain rates to better understand the behavior of. HPFRCC and propose the standard loading rate for compressive and tensile tests of new HPFRCC materials. The results show that there is a substantial increase in the ultimate compressive and tensile strength with increasing strain rate.

• Structural Engineering and Mechanics
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• v.65 no.3
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• pp.343-348
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• 2018

This paper reports mechanical behavior of recycled fine aggregate concretes after high temperatures. It is found that compressive strength of recycled fine aggregate concretes decline significantly as the temperature rises. The elastic modulus of recycled fine aggregate concretes decreases with the increase in temperature, and the decrease is much quicker than the decrease in compressive strength. The split tensile strength of recycled fine aggregate concrete decrease as the temperature rises. Through the regression analysis, the relationship of the mechanical behavior with temperature are proposed, including the compressive behavior, elastic modulus and split tensile strength, which are fitting the test data.

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.495-508
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• 2012

The strength theory of concrete is significant to structure design and nonlinear finite element analysis of concrete structures because concrete utilized in engineering is usually subject to the action of multi-axial stress. Experimental results have revealed that lightweight aggregate (LWA) concrete exhibits plastic flow plateau under high compressive stress and most of the lightweight aggregates are crushed at this stage. For the purpose of safety, therefore, in the practical application the strength of LWA concrete at the plastic flow plateau stage should be regarded as the ultimate strength under multi-axial compressive stress state. With consideration of the strength criterion, the ultimate strength surface of LWA concrete under multi-axial stress intersects with the hydrostatic stress axis at two different points, which is completely different from that of the normal weight concrete as that the ultimate strength surface is open-ended. As a result, the strength criteria aimed at normal weight concrete do not fit LWA concrete. In the present paper, a multi-axial strength criterion for LWA concrete is proposed based on the Unified Twin-Shear Strength (UTSS) theory developed by Prof Yu (Yu et al. 1992), which takes into account the above strength characteristics of LWA under high compressive stress level. In this strength criterion model, the tensile and compressive meridians as well as the ultimate strength envelopes in deviatoric plane under different hydrostatic stress are established just in terms of a few characteristic stress states, i.e., the uniaxial tensile strength $f_t$, the uniaxial compressive strength $f_c$, and the equibiaxial compressive $f_{bc}$. The developed model was confirmed to agree well with experimental data under different stress ratios of LWA concrete.

• Advances in materials Research
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• v.8 no.2
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• pp.103-115
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• 2019

Polypropylene (PP) fibers for making fabric which is used for packing cement have a high strength and high tear resistance. Due to these excellent properties the present study investigates the effect of PP fibers on the mechanical strength of concrete. Mechanical strength parameters such as compressive strength, splitting tensile strength and flexural strength are evaluated. Structural integrity of concrete using Ultrasonic Pulse Velocity (UPV) was also studied. Concrete containing PP fibers in percentage of 0%, 0.15%, 0.25%, 0.5% and 0.75% was developed with a characteristic compressive strength of 25 MPa. Concrete cubes, cylinder and prismatic specimens were cast and tested. It was found that the UPV values recorded for all specimens were of the similar order. Test results indicated the used of PP fibers can significantly improve the flexural and splitting tensile strengths of concrete materials whereas it resulted a decreased in compressive strength. The relative increase in split tensile and flexural strength was optimum at a fiber dosage of 0.5% and a mild decreased were observed in 28 days compressive strength. The findings in this paper suggested that PP fibers deriving from these waste cement bags are a feasible fiber option for fiber-reinforced concrete productions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.5
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• pp.603-613
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• 2024

This study evaluated the mechanical properties of high-tension performance biochar concrete, focusing on the effects of varying biochar cement replacement ratios (0 %, 1 %, 2 %, 3 %, 4 %, and 5 %). Mechanical properties, including compressive strength, tensile strength, and flexural strength, were tested. The results showed a general decrease in compressive strength with increasing biochar replacement, with significant reductions at 1 % to 3 % levels. PVA fiber reinforcement improved long-term compressive strength, particularly at higher biochar levels. Tensile and flexural strength also showed initial reductions with low biochar levels but improved at higher replacement levels. PVA fibers consistently enhanced tensile and flexural strength. SEM images confirmed the integration of biochar and PVA fibers into the cement matrix, enhancing microstructural density and crack resistance.

• Journal of the Korean Geotechnical Society
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• v.32 no.8
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• pp.27-33
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• 2016

In this study, Polyvinyl alcohol (PVA) fiber was used to increase strength (unconfined compressive strength and tensile strength) of bio-cemented sand using microorganism. Ottawa sand was mixed with PVA fibers having three fiber contents (0, 0.4, and 0.8%). The fiber mixed sand was treated 14 times by using Microbially Induced Calcite Precipitation (MICP) which included culture (2 times per day) during 7 days to improve its engineering properties. The Bacillus Sporosarcina pasteurrii (Bacillus sp.) was used for urease activity. The specimen was prepared as a cylindrical specimen of 5 cm in diameter and 10 cm in height. Unconfined compressive strength and tensile strength were measured after cementation. Moreover, calcium carbonate content and SEM analyses were performed with a piece of sample. An average value of unconfined compressive strength increased and then slightly decreased but an average value of tensile strength ratio increased with increasing carbonate content the in same condition. Unconfined compressive strength and tensile strength increased about 30% and 160%, respectively. A strength ratio of unconfined compressive strength to tensile strength representing the brittleness decreased from 8 to 4 when fiber content increased from 0.0 to 0.8%. Such bio-cemented sand can be applied into slope area to prevent its shear failure or increase its tensile strength.