• 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 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.589-592
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• 2006

The durability of concrete involves resistance to freeze-thaw action, corrosion, permeation, carbonation, chemical attack and so on. Generally, properties of concrete have been well understood under the separate action of these deterioration mechanisms. However, in practice, the degradation of concrete usually is the result of combined action of physical and chemical attack and can be accelerated by the combined action of several deterioration mechanisms. In the present study, to evaluate the combined deterioration by freeze-thaw action and seawater attack, ground granulated blast-furnace slag or silica fume concrete with water or seawater as mixing water was exposed to 300 cycles of freeze-thaw action. Tests were conducted to determined the relative dynamic modulus of elasticity and compressive strength. Furthermore, The MIP analysis were performed on the deteriorated part of concrete due to freeze-thaw action and seawater attack.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.416-421
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• 1997

This study was conducted to evaluate durability of high-strength light-weight aggregate concretes which are increasingly demanded recently. Two different artificial light-weight aggregates were used and two levels of high-strength concretes were made using w/c of 33% and 37% for target strength of 500kg/$\textrm{cm}^2$ and 400kg/$\textrm{cm}^2$, respectively. Cylinder specimens($\phi$=10cm and h=20cm) were made and treated with freezing-and-thawing(F/T) cycle at $-18^{\cire}C$ and $4^{\cire}C$. Dynamic modulus of elasticity and surface condition were evaluated with F/T cycle increase. The results showed that durability of the light-weight aggregate concretes was worse than that of conventional concrete, and the light-weight high-strength concrete with w/c=37% had the better durability than the one with w/c=33%.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.399-402
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• 2003

This study is performed to examine the physical and mechanical properties of the high strength concrete using recycled aggregate. The recycled aggregate is replaced by 0%, 25%, 50%, 75%, 100% of natural crushed aggregate. The compressive strength of the concrete used recycled aggregate is shown in more than $400kgf/cm^2$ at the curing age 28 days. But the pulse velocity and dynamic modulus of elasticity are decreased with increasing the content of recycled aggregate. Accordingly, these recycled aggregate concrete can be used for high strength concrete.

• Journal of Industrial Technology
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• v.17
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• pp.227-232
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• 1997

This study was conducted to evaluate durability of concrete which are increasingly demanded recently. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio, Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at $-18^{\circ}C$ and $4^{\circ}C$. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that decreasing W/C ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.161-166
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• 1998

This experiment was on purpose to estimate freezing and thawing resistance concering with developing rice straw ash concrete which were mixed rice straw ash to cement as ratio of cement weight. Freezing and thawing test was done by Method A of KS F 2456. It could estimate change of original mass, pulse velocity and dynamic modulus of elasticity during test. Test results showed that 5% filled rice straw ash concrete had the highest durability factor(DF) as 86 and from 5% to 7.5% filled rice straw ash concrete showed higher DF than normal cement concrete.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.395-398
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• 2003

This study is performed to evaluate the engineering properties of cement mortar with hwangtoh and fly ash The absorption ratio is in the range of $5.22{\sim}13.16%\;and\;8.53{\sim}13.29%$ at the curing age 14 and 28 days, respectively. The compressive strength is in the range of $92{\sim}458kgf/cm^2\;and\;88{\sim}316kgf/cm^2$ in water and dry cruing at the curing age 28days, respectively. The bending strength and dynamic modulus of elasticity are shown in similar tendency in water and dry curing.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.109-112
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• 2006

Social and environmental pressures draw greater significance on the recycling of the waste. Particularly, waste concrete is particularly crucial among the construction wastes in terms of conservation of natural construction resources as well as disposal crisis. The technology to recycle the waste concrete has been improved. This study has various replacement levels of natural fine aggregate with recycled fine aggregate while coarse aggregate is completely replaced with the recycled coarse aggregate and herein fundamental properties investigated include compressive strength, shrinkage and dynamic modulus of elasticity. As a result, it is anticipated that the recycled aggregate concrete can be successfully applied to structural concrete members provided a proper recycling process, mix design and curing method are practiced.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.211-212
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• 2010

This study is aimed to investigate effects of water-cement ratio on the freeze thaw resistance of fly ash concrete. Assess the effects of physical properties of fly ash concrete by measure the length change, weight change, dynamic modulus of elasticity.