• Computers and Concrete
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• v.9 no.5
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• pp.389-402
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• 2012

In this study, the modulus of elasticity of low, normal and high strength steel fiber reinforced concrete has been predicted by developing a fuzzy logic model. The fuzzy models were formed as simple rules using only linguistic variables. A fuzzy logic algorithm was devised for estimating the elastic modulus of SFRC from compressive strength. Fibers used in all of the mixes were made of steel, and they were in different volume fractions and aspect ratios. Fiber volume fractions of the concrete mixtures have changed between 0.25%-6%. The results of the proposed approach in this study were compared with the results of equations in standards and codes for elastic modulus of SFRC. Error estimation was also carried out for each approach. In the study, the lowest error deviation was obtained in proposed fuzzy logic approach. The fuzzy logic approach was rather useful to quickly and easily predict the elastic modulus of SFRC.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.437-443
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• 2009

Impact echo method estimating the soundness of concrete measures the dynamic elastic modulus of specimens which are different with static elastic modulus tested by uni-axial compression test. Thus, this paper investigates the relationships between dynamic and static elastic modulus based on in-situ concrete cores. Also, dynamic elastic modulus was compared with compressive strength. Concrete cores were obtained from about 20 to 70 years concrete structures at three different harbors which were Incheon, Wando, and Masan in Korea. In order to investigate the influence of exposure condition on the relationship, air zone, splash zone, and tidal zone were selected. Different harbors showed the different relationships between dynamic and static elastic modulus, but exposure conditions have no influence on the relationship between dynamic and static elastic modulus. Also, the relationship between dynamic elastic modulus and compressive strength has the same tendency as the relationship between dynamic and static elastic modulus. The relationship equations were proposed to estimate the relationships properly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.4
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• pp.1215-1225
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• 2014

Volcanic rocks formed from magma near the earth surface commonly show vesicular structures due to exsolution of gaseous phases in magma. The distinction and the amount of vesicles are greatly various, but there are few researches on the effect of volume percentage of vesicles on the mechanical properties. In this study, mechanical characteristics of volcanic rocks in relation to the porosity are investigated through experimental tests with Jeju basalt. Two methods (the buoyancy method and the caliper method) are adopted for measuring porosity. And unconfined compressive strength, elastic modulus, tensile strength, and elastic wave velocity are plotted against porosity in order to propose the empirical relations after the regression analysis. Also, unconfined compressive strength and the elastic modulus in relation to the elastic wave velocity are proposed with the analysis. In the case of vesicular rocks with more than 5% porosity, it is found that the buoyancy method provides more accurate estimation of porosity than the caliper method. The unconfined compressive strength, the elastic modulus, and the elastic wave velocity decrease curvilinearly with increasing in porosity. Also, the unconfined compressive strength and the elastic modulus increase linearly with increasing in elastic wave velocity.

• Advances in concrete construction
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• v.13 no.3
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• pp.215-221
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• 2022

Considering their similar mass densities, an attempt was made to optimize the mix design of micro-concrete that used barite sand as an aggregate by substituting marble powder (5%, 10%, 20%, 30%, 40%, 50%, 70%), clay brick powder (30%, 50%, 70%), and fly ash (30%, 50%, 70%) for the concrete (by mass) to form specimens for shaking table tests. The test results showed that for these three groups of materials, the substitutions had little effect on the density. The barite sand played a decisive role in the density, and the overall density of the specimens reached approximately 2.9 g/cm³. The compressive strength and elastic modulus decreased with an increase in the substitution rates for the three types of materials. Among them, the 28 day compressive strength values of the 40% and 50% marble powder groups were 11.73 MPa and 8.33 MPa, respectively, which were 58.7% and 70.7% lower than the control group, respectively. Their elastic modulus values were 1.33×10⁴ MPa and 1.42×10⁴ MPa, respectively, which were 39.1% and 35% lower than those of the control group, respectively. The 28 day compressive strength values of the 50% and 70% clay brick powder groups were 13.13 MPa and 5.8 MPa, respectively, which were 53.8% and 79.6% lower than the control group, respectively. Their elastic modulus values were 1.54×10⁴ MPa and 1.19×10⁴ MPa, respectively, which were 29.7% and 45.4% lower than those of the control group, respectively. The 28 day compressive strength values of the 50% and 70% fly ash groups were 13.5 MPa and 7.1 MPa, respectively, which were 52.5% and 75% lower than those of the control group, respectively. Their elastic modulus values were 1.36×10⁴ MPa and 0.95×10⁴ MPa, respectively, which were 37.9% and 56.6% lower than those of the control group, respectively. There was a linear relationship between the 28 day compressive strength and elastic modulus, with the correlation coefficient reaching a value higher than 0.88. The test results showed that the model materials met the high density, low compressive strength, and low elastic modulus requirements for shaking table tests, and the test data of the three groups of different alternative materials were compared and analyzed to provide references and assistance for relevant model testers.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.159-163
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• 1995

The purpose of this experimental research is to not only devlop the high-strength concrete using sea and river sand, but also investigatc mechanical properites of the high-strength concrete, such as the elastic modulus, the compressive strength of concrete cyllinder, and etc. Also, rational analytical formula for elastic modulus has been proposed together with those for the splitting tensile strength and the flexural strength to be predicted from compressive strength of conccrete cyllinder.

• Advances in concrete construction
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• v.8 no.1
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• pp.1-7
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• 2019

The possibility of using recycled coarse glass aggregates as a substitute for natural crushed stone are relatively limited. In order to promote it for engineering application, this paper reports the effect of coarse glass aggregate on mechanical behavior of concrete. The coarse aggregates are substituted for coarse glass aggregate (CGA) as 0%,20%,40%,60%,80% and 100%.The results show that increasing the coarse glass aggregate content cause decrease in compressive strength, the elastic modulus, the splitting tensile strength, the flexural strength. An equation is presented to generate the relationship between cube compressive strength and prism compressive strength, the relationship between cube compressive strength and elastic modulus, the relationship between cube compressive strength and splitting tensile strength, the relationship between cube compressive strength and flexural strength of coarse glass concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.37-42
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• 2001

This paper presents the improved elastic modulus equation more appropriate to predict the modulus of elasticity of structural elements designed and made by high-strength concrete. To propose the elastic modulus equation, more than 300 laboratory specimen tests having the range of 5n to 800kgf/$cm^{2}$ in concrete compressive strength were conducted and analyzed statistically. The equation derived in terms of empirical constant, the elastic moduli of coarse aggregate and mix proportions. Comparison of the proposed elastic modulus equation with the previously suggested equations in the ACI363R, and New-RC were also presented to demonstrate the applicability to practice.

• Journal of the Korean Geotechnical Society
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• v.25 no.8
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• pp.65-76
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• 2009

Little attention has been paid to Brazilian test for the estimation of uniaxial compressive strength and elastic modulus of rocks as an indirect method despite high availability of civil engineering parameters. This paper employed Brazilian test value to estimate two parameters of igneous rocks (granite, andesite, rhyolite) of Korea. High reliability of Brazilian test has been supported by the conclusions drawn from point load test and Schmidt hammer strike values. It has also been found that this method can be applied easily and rapidly to the estimation of uniaxial compressive strength and elastic modulus of rock cores when direct tests are not available.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.89-92
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• 2005

An experimental study was conducted to study the mechanical properties of recycled aggregate concrete in accordance with the different replacement ratios of recycled fine and coarse aggregate, ranging from 0$\%$ to 30$\%$ and 0$\%$ to 50$\%$, respectively. According to increase of these replacement ratios, compressive strengths and elastic modulus are reduced down to $10\∼20\%$ and $15\∼30\%$, respectively. The reducing ratios of elastic modulus are more distinct than that of compressive strength. For the selection of replacement ratios of recycled aggregate for structural concrete properly, it is necessary to evaluate the elastic modulus carefully.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.2
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• pp.144-151
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• 2017

The mechanical properties such as compressive strength and elastic modulus of recycled aggregate concrete containing fly ash are investigated in this study. The experimental parameters were replacement ratio of recycled coarse aggregate(RCA) and fly ash. Replacement ratio of RCA was 0, 30, 50, and 70% and replacement ratio of fly ash was 0, 15, 30%. The experimental results were extensively discussed about compressive strength and elastic modulus of concrete at ages of 7, 28 and 91 days. Compared with concrete not containing fly ash, the decrease of compressive strength and elastic modulus of concrete containing fly ash with the replacement ratio of 30% was significant. Therefore, the test results represented that the fly ash replacement ratio of less than 30% was favorable in terms of mechanical properties of recycled coarse aggregate concrete.