• Architectural research
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• v.10 no.2
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• pp.27-35
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• 2008

Because of several advantages of mortar-filled sleeve splice in reinforced concrete buildings, this method is being applied increasingly at construction sites and various methods of the splice have been developed in Korea and other countries. In order to apply this system in the field, studies on mortar-filled sleeve splice have been mainly experimental research focused on overall structural performance. However, for understanding the structural characteristics of this splice more accurately, we need to study the confining effect of sleeve, which is known to affect bond strength between filling mortar and reinforcing bar, the most important structural elements of the bar splice. Thus, in order to examine the confinement effect of mortar-filled steel pipe sleeve splice, the present study prepared actual-size specimens of steel pipe sleeve splice, and conducted a loading. Using the test results, we analyzed how the confining effect of steel pipe sleeve affects the bond strength of this splice and obtained data for developing more reasonable methods of designing the splice of reinforcement.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.437-439
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• 2007

This paper was analyzed the resistivity change characteristic of mortar model block and concrete that was made earth electrode that's used concrete or basic concrete of building for 1 year. The early resistivity measurement value of concrete model block is higher than mortar model block. But after 1 year the resistivity measurement value of mortar model block is significantly higher than concrete model block. Because depends on time elapsed complete dryness factor of mortar model block that has not gravel is higher than concrete model block. And absorptance and function of mortar mode block was by far outstanding than concrete model block in the data for verification of the amount of contained water and the amount of dryness of mortar model block and concrete model block.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.203-208
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• 1999

The purpose of this study is to examine the bond properties of polymer cement mortar. Generally, cement mortar using polymer has been used that recovering the deteriorative concrete structure performance. In this case, it is very important problem to become a monolithic construction by bonding property. In this study, it is evaluated with other properties that adhesion strength between polymer cement mortar and concrete substrate. And polymer cement mortar was compared with plain cement mortar by scanning electron microscope.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.343-348
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• 1999

The purpose of this study is to evaluated the effects of added expanded polystyrene on the basic properties of UP mortar. Polyester resin mortars are prepared with expanded polystyrene ratio in styrene monomer (EPS/PS), and the ratio of total polystyrene resin to UP resin (PS/UP). And it is tested for viscosity of UP resin added PS resin, slump-flow test, working life, flexural and compressive strengths, and curing shrinkage test. From the test result, Viscosity of resin for polymer mortar increases with increasing PS content. Curing shrinkage of UP mortar is considerably smaller than that of plain UP mortar, nevertheless, reduction in the strengths is not recognized according to adding PS resin. In this study, we can obtain the optimum mix proportions of polymer mortar using PS resin.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.727-730
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• 2005

The purpose of this study evaluates possibilities of waste phosphogypsum into concerts by steam curing admixture. The waste phosphogypsum is made use of 4 forms(Dehydrate, $\beta$-Hemihydrate, III-Anhydrite and II-Anhydrite) which were changed to in low temperature of calcination. The penetration depth and compressive strength of cement mortar are investigated to evaluate the chloride ion and carbonation resistance. As a result, chloride ion and carbonation resistance of cement mortar admixed with waste phosphogypsum are more excellent than cement mortar contained OPC alone. The internal pores of cement mortar are decreased by using waste phosphogypsum, because the hydrates of ettringite which is denesified in structure is much formed in early ages at steam curing. These densified effect is concluded with improving the resistance to attack of cement mortar including waste phospogypsum.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.639-642
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• 2005

Main components of metakaolin(MK) were $SiO_2\;and\;Al_2O_3$. and specific surface was 2.2 times larger than that of ordinary portland cement(OPC). MK indicated the fine particle and fiber texture. Flow value of mortar with MK was decreased linearly each $13\%$ as the replacement ratio of MK was increased each $5\%$. Compressive strength of mortar with MK was increased more than that of mortar with OPC by 3days. Compressive strength of mortar with $10\%$ MK was about 83MPa at 28 days. When MK was replaced with $10\%$ of cement volume, flexural strength and modulus of elasticity of mortar was indicated the maximum value at 28 days.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.285-288
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• 2006

Recently, polymer mortar has been developed not only more improving the performance of modified mortar with polymer, but also protecting and repairing materials of structures, especially in marine environment because of their excellent performance to improve compressive strength, flexural strength, and adhesive strength. however, in fact, these rehabilitation techniques in marine environment, which consist of removing delaminated areas of concrete, cleaning affected steel and patching with polymer mortar, have proven to be ineffective for marine structures. Also, repairs are often repeated every several years. Therefore, it is neccessary to research performance evalution of chloride ion penetration of polymar mortar for section restoration.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.93-102
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• 1995

In this study the characteristics of adiabatic and lightweight of cement mortar was improved by using porous Bottom ash which was industrial waste. when a foaming agent was added, the characteristics of mortar using sand and Bottom ash were compared. From the empirical results the heat-transfer ratio for the mortar using Bottom ash only was shown the lower values than that for a general mortar, and the lightweight concrete with unit weight of 1.5t/$\textrm{m}^3$ could be made. When the foaming agent of 0.25% and 0.5% in usage of cement was added to that, the compressive strength scould be measured as 5 and 8times of the general mortar respectively. Also, the characteristics of adiabatic for that mortar was great improved so that the heat-transfer ratio was fallen to 0.172kcal/$mh^{\circ}C$.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.30-35
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• 1996

Accumulations of worn-out automobile tires creat fire and health hazards. As a possible solution to the problem of scrap-tire disposal, an experimental study was conducted to examine the potential of using tire chips as aggregate in rubber mortar. This paper examines strength and toughness properties of rubber mortar in which different amounts of rubber-tire particles of several sizes were used as aggregate. The rubber mortar mixtures exhibited lower compressive, bending, tensile than did normal mortar. However, these mixtures did not demonstrate brittle failure, but rather a ductile, plastic failure, and had the ability to absorb a large amount of plastic energy under compressive loads.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.828-833
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• 2003

In this paper, a study on fracture characteristics of chemically prestressed mortar with addition of expansive additives was carried out. Uni-axial tension tests with reinforced mortar specimen restrained by embedded reinforcing bar and three point bending tests with notched steel fiber reinforced beams were carried out to verify the characteristics of the cracking behavior, the tension stiffening effect due to bond between rebar and mortar, and fracture characteristic. Tension stiffening curve for the chemically prestressed mortar was obtained from uni-axial tension test. And increased fracture energy due to the chemical prestress was also obtained from bending test and tension softening curve for chemically prestressed mortar was also obtained.