• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.676-681
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• 1997

The purpose of this study is to evaluate the thermal Conductivity and Foolr Impact Sound of Polyurethane Concretes. The Polyurethane Concretes are prepared with various resin content, Fine and Coarse aggregates content, and its thickness, and tested for the Thermal Conductivity and Impact Sound. From the test results. the sound insulation grade of polyurethane concretes by the floor impact sound test on high frequency band is L-60, and its effect is considerable Polyurethane concretes have high degree of solidity compared with other heat shield materials, and its thermal conductivity is 0.05kcal/$mh^{\cire}C$. And it is suitable for sound proof floor materials.

• Advances in concrete construction
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• 제2권3호
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• pp.193-207
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• 2014

The study presented herein aims to investigate the durability related properties of rubberized concrete. Two types of waste scrap tire rubber were used as fine and coarse aggregate, respectively. The rubber was replaced with aggregate by three crumb rubber and tire chips levels of 5, 15, and 25% for the rubberized concrete productions. In order to improve the transport properties and corrosion resistance of rubberized concretes, SF was replaced with cement at 10% replacement level by weight of total binder content. The transport properties of the rubberized concretes were investigated through water absorption, gas permeability, and water permeability tests. The corrosion behavior of reinforcing bars embedded in plain and silica fume based rubberized concretes was investigated by linear polarization resistance (LPR) test. The results indicated that the utilization of SF in the rubberized concrete production enhanced the corrosion behavior and decreased corrosion current density values. Moreover, the reduction in the water and gas permeability coefficients was observed by the incorporation of SF in plain and especially rubberized concretes.

• 한국환경복원기술학회지
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• 제2권2호
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• pp.62-69
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• 1999

This study was carried out to find out the capability of applying such materials as porous concrete, could be called environmentally friendly materials, for bringing vegetations. For verying the purpose of the experiments such materials as potland cement and slag cement, coarse aggravates(${\phi}25mm$, ${\phi}18mm$, ${\phi}13mm$) were mixed. In the voids of porous concrete peatmoss and chemical fertilizers were filled, and on the surface of concrete organic soils were adhered for seeding grasses. For testing compressive strength, pH, voids the 12($4mixed{\times}3times$) specimens were manufactured. As results, the compressive strength of porous concretes were from 59 to $267kg/cm^2$ depend on mixed ratios between cements and coarse aggregates. Voids of concrete were from 33% to 40% and the pH were varied pH 8-10.5. So the capability of planting vegetations was to be ascertained. The germination and growth of grasses were not good, but it could be found out that the capability of vegetations on the concretes. For generalizing these results and applying on the construction sites, it is necessary to verificate following studies for various conditions.

• International Journal of Concrete Structures and Materials
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• 제4권2호
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• pp.97-104
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• 2010

The crushed limestone sand is an abundant material in Tunisia, which induces many environmental problems. Indeed, available stocks of siliceous sand drastically decrease because of its massive use in hydraulic concrete. Some recent research works, carried out in Tunisia, concluded that crushed limestone sand may be used in concrete manufacture instead of siliceous sand traditionally used. In this context, an experimental study was achieved in order to quantify the influence of a partial or total substitution of siliceous sand by crushed limestone sand on hydraulic concrete performances. Preliminary chemical and physical tests on crushed sand indicated that it presented the minimum requirement for its use as aggregate in hydraulic concrete. 79 concretes were then prepared with siliceous sand, crushed limestone sand and a mix of the two sands. Their slump value and compressive strengths were measured on plain concretes. Complementary structural tests on reinforced concrete beam were also performed. The results proved that crushed limestone sand concretes showed workability and mechanical performances closed to those of siliceous sand concretes.

• Computers and Concrete
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• 제13권1호
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• pp.17-30
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• 2014

This research presents the effect of various ground pozzolanic materials in blended cement concrete on the strength and chloride penetration resistance. An experimental investigation dealing with concrete incorporating ground fly ash (GFA), ground bottom ash (GBA) and ground rice husk ash (GRHA). The concretes were mixed by replacing each pozzolan to Ordinary Portland cement at levels of 0%, 10%, 20% and 40% by weight of binder. Three different water to cement ratios (0.35, 0.48 and 0.62) were used and type F superplasticizer was added to keep the required slump. Compressive strength and chloride permeability were determined at the ages of 28, 60, and 90 days. Furthermore, using this experimental database, linear and nonlinear multiple regression techniques were developed to construct a mathematical model of chloride permeability in concretes. Experimental results indicated that the incorporation of GFA, GBA and GRHA as a partial cement replacement significantly improved compressive strength and chloride penetration resistance. The chloride penetration of blended concrete continuously decreases with an increase in pozzolan content up to 40% of cement replacement and yields the highest reduction in the chloride permeability. Compressive strength of concretes incorporating with these pozzolans was obviously higher than those of the control concretes at all ages. In addition, the nonlinear technique gives a higher degree of accuracy than the linear regression based on statistical parameters and provides fairly reasonable absolute fraction of variance ($R^2$) of 0.974 and 0.960 for the charge passed and chloride penetration depth, respectively.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.749-752
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• 2008

본 연구는 섬유혼입 초속경 폴리머 시멘트 콘크리트의 강도 특성에 미치는 섬유 혼입량 의 영향을 검토한 것이다. 그 결과, 섬유혼입 초속경 폴리머 시멘트 콘크리트의 압축 및 휨강도는 섬유 혼입량이 증가함에 따라 증가하였다. 특히 폴리머-시멘트비 20%, 섬유 혼입량 0.12%인 콘크리트의 휨강도는 폴리머 미혼입 시멘트 콘크리트보다 2배 이상의 강도발현을 나타냈다. 이와 같은 강도발현은 폴리머 및 섬유의 높은 인장강도와 폴리머 및 섬유의 혼입에 의한 시멘트 수화물과 골재간의 접착성이 개선되었기 때문이라 판단된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.130-135
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• 2000

The purpose of this study is to examine the physical properties of water-permeable concretes. The water-permeable concrete with cement-aggregate ratios of 1:3.5 to 1:6.0 and two type of coarse aggregate size of 8~13 and 13~18mm used OPC(ordinary portland cement) as a binder and superplasticizer are prepared, and then tested for flexural strength, compressive strength, compressive strength, continuous void percentage and coefficient of water permeability. It is concluded from the test result that the superior flexural and compressive strengths, coefficient of water permeability and continuous void percentage of water-permeable concretes that use OPC were obtained at cement-aggregate ratios of 1:3.2, 1:6.0 respectively, The water-permeable concretes with coarse aggregate of 8~13 and 13~18mm size used OPC as a binder havinga flexural strength of 24.81~45.56kgf/$\textrm{cm}^2$, 21.99~40.62kgf/$\textrm{cm}^2$, a compressive stength of 93.63~ 242kgf/$\textrm{cm}^2$, 114.8~191.7.kgf/$\textrm{cm}^2$, a coefficient of permeability of 0.59~1.85kgf/$\textrm{cm}^2$, 0.73~ 2.25kgf/$\textrm{cm}^2$, and a continuos void percentage of 16.6~26.32%, 13.52~24.35% respectively during 28 curing days.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2005년도 학술발표논문집
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• pp.97-101
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• 2005

High strength concretes utilizing EVA with micro particles were prepared by varying polymer/binder mass ratio and curing conditions with a constant water/binder mass ratio of 0.3. The EVA modified concretes on the compressive and flexural strength, microstructure, ultrapulse modulus in curing condition(dry and water curing) were studied. Also, scanning electron microscope analysis(SEM) was performed to reveal the presence of polymer film and cement hydrates in the concrete. The compressive strength of the EVA modified concretes cured at water conditions ere higher than that of the EVA modified concretes cured at dry conditions. But, the flexural strength of the specimens cured at dry conditions were higher than that of the specimens cured at water conditions. Due to the interaction of the cement hydrates and polymer film, an interpenetrating network originated in which the aggregates were embedded. The curing of the polymer modified concrete involves two step of cement hydrates and polymer modification, and cement hydrates was promoted in water conditions and polymer film formation take place when water evaporates and was thereby was favored in dry conditions. By SEM analysis, influences of polymer modification was strengthening of the transition zone between the aggregate and the paste, and the porosity of transition zone decreases. By spring analysis, it could known that polymer film affects in porosity decrease and strengthening of transition zone.

• Computers and Concrete
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• 제3권2_3호
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• pp.163-175
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• 2006

This research was conducted to determine effect of pumice aggregate ratio, cement dosage and slumps on freeze-thaw resistance, density, water absorption and elasticity of concrete. In the first batch, $300kg/m^3$ cement dosage were kept constant and pumice ratios were changed as 25%, 50%, 75% and 100% of replacement for normal aggregate by volume for $3{\pm}1cm$, $5{\pm}1cm$ and $7{\pm}1cm$ slumps. Other batches were prepared with $200kg/m^3$, $250kg/m^3$, $350kg/m^3$, $400kg/m^3$ and $500kg/m^3$ cement dosages and 25% pumice aggregate +75% normal aggregate at a constant slump. Test results showed that when pumice-aggregate ratio decreased the density and freeze-thaw resistance of concretes increased. With increasing of cement dosage in the mixtures, density of the concretes increased, however, freeze-thaw resistance of concretes decreased. Water absorption of the concrete decreased with increasing cement dosage but increased with the pumice ratio. Water absorption of the concrete also decreased after freeze-thaw cycles. Freeze-thaw resistance of concretes was decreased with increasing the slumps.

• Computers and Concrete
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• 제18권2호
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• pp.279-295
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• 2016

A new innovative composite material is textile reinforced cementitious composite (TRCC). To achieve high flexural performance researchers suggest polymer modification of TRCC matrices. In this study, nine ready mix repair mortars commonly used in construction industry and the production of TRCC elements were examined. Mechanical properties such as compressive and flexural strength, drying shrinkage were studied. Being a significant durability concern, alkali silica reaction tests were performed according to related standards. Results showed that, some ready repair mortar mixes are potentially reactive due to the alkali silica reaction. Two of the ready mortar mixes labelled as non-shrinkage in their technical data sheets showed the highest shrinkage. In this experiment, researchers designed new matrices. These matrices were fine grained concretes modified with polymer additives; latexes and redispersible powders. Two latexes and six redispersible powder polymers were used in the study. Mechanical properties of fine grained concretes such as compressive and flexural strengths were determined. Results showed that some of the fine grained concretes cast with redispersible powders had higher flexural strength than ready mix repair mortars at 28 days. Matrix composition has to be designed for a suitable consistency for planned production processes of TRCC and mechanical properties for load-carrying capacity.