• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.21-24
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• 1989

The effect of superplasticizing agents on the mechanical properties in hardened concrete have been analyzed and investigated under various mix proportions of water cement ratio of 0.40, 0.50, 0.60 and 0.70, Superplasticizing agents of NL-4000, and Rheobuild-716, and addition rate of sp. agents of 0.0, 0.5, 1.0, 1.5 and 2.0 in the practical range. It is the aim of this study to provide the fundamental data on the compressive strength, dynamic and static modulus of elasticity, stress and strain curve of hardened concrete comparing with base concrete and conventional concrete for the practical use and research data accumulation of superplasticized concrete in the side of development of concrete construction technology and management.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.412-418
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• 2010

This paper presents the results of experimental work on both mechanical properties and durability of concrete or mortar incorporating silica fume. The aim of this study was to investigate the effect of replacement of silica fume on the performance of hardened concrete or mortar. The replacement levels of silica fume that replaced cement in this work were 0%, 5%, 10% and 15%, respectively. The results of this study indicate that both mechanical properties and durability of concrete are greatly dependent on the replacement levels of silica fume. As the replacement level of silica fume increased, the mechanical properties including compressive and flexural strengths, and static modulus of elasticity were proportionally enhanced. Furthermore, it was found that silica fume had some beneficial effects on the resistances to both chloride ions penetration and sodium sulfate attack. However, it exhibited poor resistances to both freezing-thawing action and magnesium sulfate attack.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.1
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• pp.83-92
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• 1997

An experimental study of the application of Silica fume for the high strength concrete was conducted. Nine specimens with three different contents of silica fume, 0%, 10%, 20% and with three water-cement ratio 30%, 40%, 50% were tested. Results shows that 10% of silica fume and 30% of water-cement ratio has a maximum strength with 700kg/$cm^2$ of compressive strength and 64kg/$cm^2$ of splitting tensile strength and 100kg/$cm^2$ of flexural strength. Slump value of the tested samples decreases with increasing water-cement ratio and elapsed time of silica fume. Splitting tensile strength$({\sigma}_f)$ and flexural strength $({\sigma}_f)$ and static modulus of elasticity(E) can be correlated with compressive strength $({\sigma}_c)$ from a regression analysis.

• Fire Science and Engineering
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• v.1 no.1
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• pp.19-26
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• 1987

In this study, fire resistance of steel fiber reinforced concrete was investigated Cylindrical and prismatic specimens made of Ordinary Portland Cement plain concrete and steel fiber reinforced concrete were exposed to heating in accordance with a standard time-temperature curve as specified in KS·F22 57, method of fire resistance test for structural parts of buildings, the period of heating was 1 hour and 2 hours. After the fire resistance test, mechanical properties of specimens such as compressive and bending strength, stress-strain curve, static and dynamic modulus of elasticity and bending toughness were investigated. Also the cracks and spallings of the specimens were observed. From the test results, it was confirmed that steel fiber reinforced concrete has a excellent fire resistance than plain concrete in the view of higher residual strength of concrete and smaller crackings because of steel fibers in concrete.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.324-329
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• 1999

This study is performed to evaluate an elastic properties of rice straw ash concrete . The following conclusions are drawn ; The ultrasonic pulse velocity is in the range of 4.084 ∼4.336㎧, which has showed abuot the same compared to that of the normal cement concrete. The highest ultrasonic pulse velocity is showed by 5% rice straw ash filled reice straw ash concrete. The dynamic and static modulus of elasticity i sin the range of 294 ${\times}$103 ∼ 347 ${\times}$103 and 266${\times}$ 103 ∼347${\times}$ 103 kgf/$\textrm{cm}^2$ , respectively. It is showed about the same compared to that of the normla cement concrete. The poisson's number of rice straw ash concrete is less than that of the normal cement concrete . The stress-strain curve of concrete which is contained rice straw ash within 10% appear slowly and over 10% appear almost straightly.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.3
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• pp.107-113
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• 2000

This study is performed to examine the physical and mechanical properties of concrete with fly ash. Test results show that the unit weights of concrete with fly ash are decreased 1-3% and the highest strength is achieved by 10% filled fly ash concrete with it is increased 7% than that of the normal cement concrete. the ultrasonic pulse velocity is in the range of 3.705~4.204m/s and the dynamic and static modulus of elasticity is in the range of 271$\times$103 ~289$\times$103kgf/cm2 and 208$\times$103 ~262$\times$103kgf/cm2 respectively. The acid-resistance is increased with increase of the content of fly ash. It is 1.2 times of the normal cement concrete by 10% filled fly ash concrete and 1.7 times by 30% filled fly ash concrete respectively.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.1
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• pp.92-98
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• 2000

This study is performed to evaluate the elastic properties of rice straw ash concrete using reices straw ash, cement, natural sand, gravel, and superplasticizer. The following conclusions are drawn ; The ultrasonic pulse velicity is in the range of 4,084 ~4,336m/s , which has showed about the same compared to that of the normla cement concrete. The highest ultrasonic pulse velocity is showed by 5 % rice straw ash filled rice straw ash concrete. The dynamic and static modulus of elasticity is in the range of 294 $\times$10$^3$ ~347 $\times$ 10$^3$ and 266 $\times$10$^3$~328 $\times$10$^3$kgf/㎤ , respectively. It is showed about the same compared to that of the normal cement concrete. The Poisson's number of rice straw ash concrete is less than that of the normal cement concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.35-38
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• 1993

Although bonding material content of the high strength flowing concrete is very important in engineering properties, in rich mix concrete increasing the bonding material content may not follow more good properties. This study is to investigate the influence of the bonding material content affecting on the engineering properties of high strength flowing concrete, and this paper is to analyze the properties of hardened concrete. The results reveal that the strength of concrete having loss bonding material content is higher than that of concrete having more bonding material content, and that in proportion to increasing of concrete strength brittleness factors decrease, and that the static modulus of elasticity in this study is less than that in specification.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.5
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• pp.99-103
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• 1999

This study examines the stress-strain and acid-resistance of pine needle ash (PNA) concrete. Materials used for this experiment are PNA , normal portland cement, natural fine and coarse aggregate. Test results show that the highest static modulus of elasticity are achieved by 5 % PNA filled PNA concrete. Acid-resistance of PNA concrete is increased with increase of the content of PNA. It is 1.29 times of the normal cement concrete for 5 % PNA filled PNA concrete and 2.57 times fo r15% PNA filled PNA concrete, based on the elased days for 25% mass loss of original mass immersed in the 5% H2SO4 solution. Accordingly, PNA concrete will greatly improve the properties of concrete.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.271-276
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• 1999

This study is performed to evaluate an elastic properties and acid-resistance of concrete using pine needle ash(PNA). Materials used for this experiment are PNA , normal portland cement, natural fine and coarse aggregate. Test results show that the highest ultrasonic pulse velocity , dynamic and static modulus of elasticity is achieved by 5% PNA filled PNA concrete, which has showed similar with those of thei normal cement concrete. Acid-resistance of PNA concrete is increased with increase of the contnet of PNA , it is 1.29 times of the normal cement concrete by 5% PNA fille PNA concrete an d2.57 times by 15% PNA filled PNA concrete . Accordingly , PNA concrete wil greatly improve the properties of concrete.