• Resources Recycling
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• v.12 no.2
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• pp.11-20
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• 2003

Limestone mine waste was used as a aggregate far permeable concrete. Void ratio, continuous void ratio, coefficient of permeability, compressive strength and flexural strength of concrete were measured and then the relationship between porosity and strength properties was investigated. Void ratio, continuous void ratio and strength properties of permeable concrete were greatly influenced by the grain size of aggregate and void filling ratio in comparison with the containing ratio of limestone mine waste. Furthermore, void ratio showed a good relation with continuous void ratio, and porosity of permeable concrete indicated a good relation with strength properties also. The coefficient of permeability of permeable concrete using limestone waste was over 0.2 cm/sec and was excellent result in comparison with normal concrete. Therefore, it could be expected that the limestone mine waste would be utilized as aggregate for pavement concrete, green concrete and water resource specie concrete in the results of this study.

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.469-475
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• 2013

The purpose of this experimental research is to estimate compressive strength and resistance to freezing and thawing of recycled aggregate concrete containing ground granulated blast furnace slag. For this purpose, concrete specimens according to substitution ratio of recycled aggregate were made for different replacement ratio of ground granulated blast furnace slag(GGBFS), and then compressive strength and resistance to freezing and thawing were evaluated for those. It was observed from the test results that compressive strength at 28 days of recycled aggregate concrete containing GGBFS of 20% was much more excellent than plain concrete and when air content of concrete was maintained 4 to 6%, influence of substitution ratio of recycled aggregate and replacement ratio of GGBFS on resistance to freezing and thawing was little up to 300 cycles of freezing and thawing.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.465-468
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• 2008

This study investigated the best condition when mixed sand with a river and crushed sand was used though the experiment for the properties of the concrete corresponding to the control of fine aggregate ratio to apply the mixed sand and properties of the fine aggregate at the ready-mixed concrete factory on Yeongnam and Honam. The physical properties of Yeongnam and Honam is satisfied with KS F 2526 and KS F 2527 except fineness modulus and passing amount of 8mm sieve. And, the mixed sand above two types which were incongruent to use individually was being used at each factory, and it was managed in accordance with KS. The flowabillity of the mixture proportion of concrete which was estimated by method of unit volume weight according to the fine aggregate ratio at each factory on Yeongnam and Honam was higher than existing mixture proportion. It was analyzed that the residual water due to decline of the surface area caused by reducing fine aggregate ratio was increased relatively. Accordingly, it was considered that the effect on the economic mixture proportion and improvement of durability might be possible.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.775-780
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• 2002

Sandwich panel made by foamed styrene and ployuretane has been used generally in the construction area because of the high thermal conductivity and light weight but they occur harmful gases to both bodies and environments in the high temperature over $50^{\circ}C$. So, the purpose of this study is to investigate the physical properties of light-weight panel using the non-structural lightweight aggregate as a part of the substitution of foamed styrene and ployuretane. This paper dealt with the effect of the addition of polymer dispersion such as SBR, St/BA-1 and St/BA-2 having polymer-cement ratio as 5, 10, 15% and the filling ratio of continuous void as 50, 60% on the strength of polymer-modified sandwich panel core. From the results, we could know that the compressive and flexural strength of the sandwich panel core using non-structural lightweight aggregate and polymer dispersion such as SBR, St/BA-1 and St/BA-2 tended to be increased with an increase in the polymer-cement ratio and the filling ratio of continuous void.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.154-155
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• 2016

Oyster shell is light weighted and its strength characteristic is similar to sand. So we produced mortar test piece using grounded oyster shell powder under 0.5mm, which is a standard of fine aggregate, and reviewed strength properties according to water cement ratio. In our test, we used two kinds of oyster shell particles: below 0.6mm and 1.2~2.5mm. Water cement ratio is varied 40% to 100% and we found that flexural strength and compressive strength are decreased in higher water cement ratio.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.183-184
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• 2020

This study evaluated the effect of foam volume ratio on shear friction behavior of bottom ash based lightweight aggregate concrete (LWA_BA). The LWA_BA with different foam volume ratio ranged between 8 and 25 MPa for compressive strength(f_ck), 17.3~62.5 kN for shear capacity at first shear crack(V_cr), 31.1~73.8 kN for shear friction capacity(V_n), and 0.01~0.03 mm for slip at maximum peak load(S₀). f_ck decreased with increase in the foam volume ratio, showing that this trend was also observed in V_cr, V_n, and S₀.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.102-105
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• 2003

The purpose of this study is to examine the influence of the flowability and the compressive strength of concrete after the improving of grain shape of the coarse aggregate and fine aggregate fineness modulus. According to the experimental results, the coarse aggregate after improvement of grain shape it lead to be down by 6% fine aggregate ratio, from 47% to 41%. The 0.5% increase of fine aggregate fineness modulus lead to 3% increase of concrete slump, and 1% reduction of concrete air content. While compressive strength on fine aggregate fineness modulus, it was increased until fineness modulus 3.0, but after it reached by 3.5 it was decreased. The compressive strength of the coarse aggregate after improving the grain shape was decreased by 6% due to loss of the adhesion of cement paste.

• Journal of the Korea Concrete Institute
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• v.19 no.3
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• pp.377-383
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• 2007

In recent years the field application of high performance concrete has been increased to improve the quality and reliability of concrete structures. The mix design of the high performance concrete includes the 2 set-off mixture theory of mortar and coarse aggregate and that of paste and aggregate. The 2 set-off mixture theory of mortar and coarse aggregate has a problem of having to determine its value through repeated experiments in applying the rheological characteristics of mortar. The 2 set-off mixture theory of paste and aggregate has never been applied to high performance concrete since it doesn't take into account the relationship between optimum fine aggregate ratio and unit volume of powder nor does it consider the critical aggregate volume ratio. As the mixture theory of these high performance concretes, unlike that of general concrete, focuses on flowability and charge-ability, it does not consider intensity features in mix design also, the unit quantity of the materials used is determined by trial and error method in the same way as general concrete. This study is designed to reduce the frequency of trial and error by accurately calculating the optimum fine aggregate ratio, which makes it possible to minimize the aperture of aggregate in use by introducing the maximum density theory to the mix design of high performance concrete. Also, it is intended to propose a simple and reasonable mix design for high performance concrete meeting the requirements for both intensity and flowability. The mix design proposed in this study may reduce trial and error and conveniently produce high performance concrete which has self-chargeability by using more than the minimum unit volume of powder and optimum fine aggregate with minimum porosity.

• Journal of the Korean Geotechnical Society
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• v.32 no.9
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• pp.29-36
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• 2016

Backfill materials of rail abutment were commonly composed with cement treated aggregate, general aggregate and soil. The friction angle of cement treated aggregate increased up to $40^{\circ}$ or more due to strength enhancement. However, $30^{\circ}{\sim}35^{\circ}$ of friction angle was typically applied for in-situ condition. This phenomenon could cause over-designing, therefore, it is essential to determine reasonable material properties of cemented treated aggregate. In this study, a series of CBR tests and circular model tests have been conducted for cement treated aggregate, while changing cement mixing ratio. Based on test results, characteristics of settlement and strength have been analyzed quantitatively. The settlement of cement treated aggregate decreased with the number of cyclic loading and aging period. In addition, The strength increment ratio in CBR test increased up to 13~16 times at 28 days aging.

• Journal of the Korea Institute of Building Construction
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• v.7 no.1 s.23
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• pp.115-121
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• 2007

Ordinary concrete uses aggregate sufficiently soaked with water, and is weighed, mixed with other materials and placed in accord with performances required in the construction field. Recently special concrete with high fluidity and durability is required but it is difficult to use top-quality concrete due to lack of high-quality aggregate, delayed transportation because of traffic jam, etc. In addition, sometimes the use of a remicon is inevitable just for small-sized concrete constructions or it is difficult for a remicon to reach remote construction places such as mountainous areas. To solve these problems, this study attempted to pack concrete materials. In other words, it is to instantize concrete. This study dried aggregate, a material of concrete, and compared the change of absorption phase of the aggregate in water and in paste in order to examine the effect of the dryness of aggregate on its absorption rate and, based on the absorption rate, decided water addition ratio necessary for the reduction of unit quantity caused by the use of dry aggregate in designing concrete mixture, and analyzed the properties of unhardened concrete according to water addition ratio in manufacturing concrete using aggregate in the state of absolute dryness and in the state of surface dryness.