• 산업기술연구
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• 제21권B호
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• pp.301-306
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• 2001

Drying shrinkage cracking which may be caused by the relatively large specific surface is a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. Therefore, the purpose of this dissertation was to study the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), latex contents(0, 5, 10, 15, 20%), W-C ratios, and curing days at a same controlled environment of 60% of relative humidity and $20^{\circ}C$ of temperature. Test results revealed that the drying shrinkage of latex modified concrete(LMC), rapid-setting cement latex modified concrete(RSLMC) was considerably lower than that of ordinary portland cement concrete(OPC), rapid-setting cement concrete(RSC), respectively. This may be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic and colloidal properties of the latexes, resulting in reduced water evaporation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1029-1034
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• 2001

The purpose of this research is to develop rapid setting cement latex modified concrete (RSLMC) which will be used to overlay bridge deck for maintaining and repairing. The main experimental variables were the types of rapid setting cement and variation of latex and antifoam agent contents were selected as admixture factor, then the properties of workability and strength development and durability properties were investigated. The results of this study show that latex content give increment of a slump due to surface tension in polymer particles and reduce unit weight of water for preservation of workability. In addition, When no and 1.6~3.2% antifoam agent were mixed, 8%, 2.0~3.8% were respectively obtained. An increasing the amount of latex produced concrete with increased flexural strength, but with slightly lower compressive strength. Rapid chloride permeability and freezing-thawing test carried out. As a results, according to increment of containing ratio antifoamer, strength of RSLMC increase, permeability showed lower value than ignorable 100 coulombs. Also, in the case of more than antifoamer 1.6%, the relativity dynamic modulus is mantained more than 90%, but in case of 0, 5%, it decrease. In consequence, with the view of strength and workability of RSLMC, it is considered that appropriate content ratio of antifoam agent and latex solid are respectively 1.6% by latex weight, 15% by cement weight.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.151-156
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• 2002

Drying shrinkage cracking which may be caused by the relatively large specific surface is a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. LMC and RSLMC were studied for field applications very actively in terms of strength and durability in Korea. However, there were no considerations in drying shrinkage. Therefore, the purpose of this study was to investigate the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), latex contents(0, 5, 10, 15, 20%), W-C ratios, and curing days at a controlled environment of 60% of relative humidity and 2$0^{\circ}C$ of temperature. The drying shrinkage for specimens was measured with a digital dial gauge of Demec. The test results showed that the drying shrinkage of LMC and RSLMC were considerably lower than that of OPC and RSC, respectively. This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.799-804
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• 2003

The purpose of this study was to investigate the effects of re-vibration and curing temperature onto the physical properties of latex-modified concrete with ordinary cement and rapid-setting cement, and thus to provide a guide line of re-vibration and curing conditions for good quality controls. The main experimental variables included two cement types(ordinary portland cement, rapid-setting cement), curing Temperature($10^{\circ}C$, $20^{\circ}C$, $30^{\circ}C$), re-vibration methods(continued, intermittent), and re-vibration times(initial setting, one day after mixing). The experimental results showed that the re-vibration affected little to the mechanical properties of LMC and RSLMC, while, the curing temperature a quite some. The early strength development was the highest at $20^{\circ}C$ curing temperature, and decreased at higher temperature. The permeability of concrete generally decreased with curing time. The rapid chloride permeability was a function of time and temperature. The chloride permeability of RSLMC was so small and negligible.

• 산업기술연구
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• 제22권A호
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• pp.161-168
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• 2002

Latex modified concrete is governed by both cement hydration and polymer film formation processes in its binder phase. Such the reactions are expected to improve the polymer-cement co-matrixes themselves and the bond between the cement hydrates and aggregates, and to improve the properties of hardened latex-modified concrete. The purpose of this study was to study the strength and chemical resistance of Rapid-setting latex modified concrete(RSLMC) with the main experimental variables such as latex content(0, 5, 10, 15, 20%) and water-cement ratio(36, 38, 40%) at latex content 15%. Water absorption test was earned out to estimate water permeability resistance. Chemical resistance test was carried out to measure the weight change and to observe the appearance of RSLMC immersion in hydrochloric acid, sulfuric acid, and calcium choloride.

• 콘크리트학회논문집
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• 제14권3호
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• pp.299-306
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• 2002

본 연구에서는 기존 교량의 신속한 유지보수를 위한 교면포장 덧씌우기용 라텍스개질 초속경 콘크리트를 개발하고자 하였다. 실험변수로는 국내 생산 초속경 시멘트를 이용하여 혼화제 인자로 라텍스 및 소포제 혼입률 변화를 선정하여 작업성, 강도발현 및 투수 특성을 고찰하고자 한다. 실험결과 동일 물-시멘트비 조건에서의 라텍스 혼입은 콘크리트의 슬럼프를 증대시켜 작업성을 유지하기 위한 단위수량을 감소시키는 것으로 나타났다. 소포제를 혼입하지 않을 때는 공기량이 8~9%로 나타났으나, 소포제를 1.6~3.2% 혼입함으로써 공기량이 2.0~3.8%로 감소되었으며, 이로 인해 압축강도가 10~20%정도 증진하였다. 라텍스의 양이 증가함에 따라 콘크리트의 휨강도는 증진되나, 압축강도는 다소 저하되었다. 그러나, 소포제의 혼입으로 타설 후 3시간 만에 교통개방을 위한 압축강도와 휨강도를 얻을 수 있었다. 라텍스를 일정량 이상 첨가할 경우 콘크리트를 불투수성의 재료로 평가할 수 있을 정도의 낮은 통과전하량을 나타내었다. 따라서 라텍스 개질 초속경 콘크리트는 구조물, 교량 포장의 덧씌우기 또는 보수재료로서 사용되어 질 수 있을 것으로 사료된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.355-360
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• 2002

The purpose of this study was to remove the excessive air foaming which was produced in mixing the RSLMC(latex-modified concrete with rapid- setting cement) by choosing the best antifoam agent type and the optimized quantity for performance improved RSLMC. A series of RSLMM(latex-modified mortar with rapid-setting cement) experiments were carried out as the basic for RSLMC with the main experimental variables such as antifiamer types(A, B, C, D), antifoamer contents(0, 1, 2, 3%). Air content test and compressive, flexural tests were carried out to measure the improved properties of RSLMM and RSLMC. Chloride ion permeability test was carried out to estimate water permeability resistance. The results of RSLMM showed that the decrease of 50% air content was obtained by admixturing a antifoam agent by 1%. The compressive strength and flexural strength at 3 hours after RSLMC placement were 235kgf/cm$^2$ and 49kgf/cm$^2$, respectively, which exceeded the flexural strength criterion of 45kgf/cm$^2$ in order to open the RSLMC placed to traffic. The chloride permeability using A and C antifoamer at 28 days were below 100 coulombs, which was the permeability rating of negligible according to ASTM.

• 산업기술연구
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• 제22권A호
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• pp.193-200
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• 2002

Drying shrinkage cracking which may be caused by the relatively large specific surface IS a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. LMC and RSLMC were studied for field applications very actively in terms of strength and durability in Korea. However, there were no considerations in drying shrinkage. Therefore, the purpose of this dissertation was to study the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), water-cement ratios and curing days at a same controlled environment of 60% of relative humidity and $20^{\circ}C$ of temperature The drying shrinkage for specimens was measured with a digital dial gauge of Demec. The test results showed that the drying shrinkage of LMC and RSLMC were considerably lower with low water-cement ratio, respectively This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation.

• 산업기술연구
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• 제21권B호
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• pp.317-324
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• 2001

This study focused on the investigation of strength development and permeability of LMC(Latex Modified Concrete) and RSLMC(Rapid-Setting Cement Latex Modified Concrete) as the latex content, cement types and w/c ratio changed. The compressive strength of latex modified concrete decreased slightly and the flexural strength increased quitely at 15% of latex content. This may be due to the flexibility of latex filled in voids and interconnections of hydrated cement and aggregates by a film of latex particles, respectively. The permeability test results showed that the permeability of LMC was considerably lower than that of conventional concrete. Results of chloride permeability test, for RSLMC indicated very low at an early age caused by the early formation of needle-shape ettringites and latex film.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.1023-1028
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• 2001

This study focused on the investigation of strength development and permeability of LMC(latex modified concrete) and RSLMC(rapid-setting cement latex modified concrete) as the latex content, cement types and w/c ratio variated. The compressive strength of latex modified concrete decreased slightly and the flexural strength increased quitely at the latex content of 15%. This may due to the flexibility of latex filled in voids and interconnections of hydrated cement and aggregates by a film of latex particles, respectively. The permeability test results showed that the permeability of LMC was considerably lower than that of conventional concrete. In the RSLMC's tests of permeability to chloride ion indicated very low permeability at an early age, which nay be due to the early formation of needle-shape ettringites and latex film.