• International Journal of Concrete Structures and Materials
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• 제19권1E호
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• pp.41-48
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• 2007

Addition of latex to concrete is known to increase its durability and permeability. The purpose of this study is to analyze air void systems in latex-modified concretes using a reasonable and objective method of image analysis with such experimental variables as water-cement (w/c) ratios, latex contents (0%, 15%) and cement types (ordinary portland cement (OPC), high-early strength (HES) cement and very-early strength (VES) cement). The results are analyzed by spacing factor, air volume (content) after hardening, air void distribution and structure. Additionally, air void systems and permeability of latex-modified concrete (LMC) are compared by a correlation analysis. The results are as follows. The LMC of the same w/c ratio showed better air entraining (AE) effect than OPC with AE water reducer. The VES-LMC showed that the quantity of entrained air below $100{\mu}m$ increased more than four times. For the case of HES-LMC, microscopic entrained air between the range of 50 to $500{\mu}m$ increased greater than 7 times even in the absence of anti-foamer. Although spacing factor was measured rather low, the permeability of latex-modified concrete was good. It is construed that air void system does not have a considerable effect on the property of latex-modified concrete, but latex film (membrane) has a definite influence on the durability of LMC.

• Korean Chemical Engineering Research
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• 제50권6호
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• pp.1076-1081
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• 2012

라텍스 개질 콘크리트의 혼화용 라텍스를 개발할 목적으로 carboxylated styrene butadiene 라텍스를 이단계 유화중합법으로 제조하고 콘크리트에 적용하는 실험을 수행하였다. 음이온 유화제로는 sodium dodecylbenzene sulfonate와 sodium salt of lauryl sulfate를 선정하였고, 라텍스 안정제로는 nonylphenoxy poly(ethyleneoxy) ethanol 계열의 동족체들(n=10, 20, 40)을, 그리고 potassium persulfate와 sodium bisulfite를 redox 개시제로, $Na_2HPO_4$와 $K_2CO_3$를 전해질로 각각 사용하였다. 중합안정성에 대한 음이온 유화제의 종류와 사용량의 영향 및 입자크기의 전해질 농도 의존성을 실험적으로 고찰하여 LMC용 라텍스 제조에 적합한 중합처방을 제시하였다. 이 중합처방으로 제조한 라텍스의 LMC 용도에 대한 적용성을 시험한 결과, 슬럼프와 공기량은 한국도로공사의 품질기준을 충족하며, 역학적 물성시험 결과에서는 28일간 경화시킨 시편의 압축강도와 휨강도가 품질기준보다 각각 39.6, 87.3% 더 높은 증진효과가 발현됨을 확인하였다.

• 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.

• 콘크리트학회논문집
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• 제13권5호
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• pp.507-515
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• 2001

신.구 콘크리트 부착계면의 부착강도는 신 콘크리트에 라텍스를 이용하여 개선할 수 있다. 그러나, 현재까지 신.구 콘크리트 사이의 부착강도를 측정하기 위해 표준으로 채택되어진 실험은 아직 없다. 일축인장시험에서, 신.구 콘크리트 계면의 부착강도는 시험체의 파단 시 인장에 의해 실제적으로 구해진다. 본 연구에서 새로이 제시한 직접인장 부착강도 실험으로 라텍스 개질 콘크리트의 부착특성을 평가하고자 하였다. 새로이 제시되는 직접인발 부착강도 실험을 위하여 현장과 같은 조건의 슬래브를 제작하여 pull-out 실험을 실시하였으며, 기존의 시편을 이용한 직접인장 실험 시편을 제작하여 본 연구에서 사용하였다. 실험결과는 다음과 같다: 라텍스 혼입율 증가에 따라 부착강도는 증가하는 것으로 나타났다. 이를 통해 라텍스에 의한 부착력증진을 확인할 수 있었다. 또한, 기존 콘크리트의 표면처리에 따른 라텍스 개질 콘크리트의 부착특성을 평가한 결과, 표면처리에 따라 라텍스 개질 콘크리트의 부착강도가 개선되는 것으로 나타났다. 기존 콘크리트의 표면함수상태에 따른 라텍스 개질 콘크리트의 부착특성을 평가하기 위해서 다양한 표면함수상태에서 부착강도를 평가한 결과, 표면건조포화상태가 가장 이상적인 조건임을 알 수 있었다.

• 한국농공학회논문집
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• 제49권4호
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• pp.35-41
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• 2007

The most agricultural concrete structures for the irrigation and drainage are exposed to the underwater condition at the irrigation period and they take the influence on very severe cold in the winter. Therefore, it is impossible to use repair materials used to the general concrete structures. The research need the development of the repair material for a performance enhance of the agricultural underwater concrete structures. This research evaluated the mechanical and durability performance of the latex modified repair mortar for underwater concrete structures which peformed the repair in the underwater according to the characteristic of the agricultural concrete structure. The latex modified repair mortar is a material that minimize the effect of the ecosystem, environment and the segregation. In this research, the construction condition of the latex modified repair mortar for agricultural concrete structures was considered and the test specimens made in the underwater condition. Test results was then compared with target performance and commercial repair mortar. Experimental test results indicated that the mechanical and durability performance of latex modified repair mortar for agricultural underwater concrete structure satisfied all target performance. Also, the latex modified repair mortar resulted in better repair performance than the commercial repair mortar.

• 콘크리트학회논문집
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• 제13권5호
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• pp.484-490
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• 2001

본 연구는 라텍스 혼입률을 5, 10, 15, 20%로 변화함에 따른 염소이온 투수성과 동결융해저항성 관점에서 라텍스 개질 콘크리트의 내구특성을 고찰하고자 한다 콘크리트에 라텍스가 혼입되고 양생되었을 때 콘크리트는 라텍스 입자의 필름막에 의해 서로 연결된 시멘트수화물과 골재가 구성된다. 이때 라텍스의 양이 증가함에 따라 콘크리트의 휨강도는 증진되나, 압축강도는 다소 저하된다. 이와 같은 휨강도의 증가는 시멘트수화물과 골재사이의 라텍스 필름막에 기인한 것이며 압축강도의 감소는 라텍스의 성분 중 부타디엔의 유연성 때문에 발생되는 것으로 판단된다. 라텍스 개질 콘크리트와 보통콘크리트의 상대 투수성을 측정하기 위하여 염소이온투과시험법을 사용하였다. 실험 결과 라텍스 개질 콘크리트의 투수성은 보통콘크리트의 투수성보다 매우 낮음을 알 수 있었다. 이것은 라텍스 미립자가 미세공극을 충전하고 라텍스 입자의 필름막에 의해 골재와 시멘트수화물이 연결되었기 때문이다. 그리고 라텍스 개질 콘크리트의 동결융해저항성은 보통콘크리트에 비해 매우 높으며, 보통콘크리트에서는 동결융해저항성을 증가시키기 위해 공기연행제를 필요로 하지만, 라텍스 개질 콘크리트에서는 적절한 양생이 이루어지면 추가적인 공기연행제는 요구되지 않는다.

• 콘크리트학회지
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• 제15권6호
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• pp.78-84
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• 2003

• 산업기술연구
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• 제24권A호
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• pp.165-171
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• 2004

Latex modification of concrete provides the material with higher flexural strength, as well as high bond strength and reduced water permeability. However, If the thermal expansion properties of overlay concrete (latex-modified concretes) are big different from that of substrate (ordinary portland cement concrete), these would cause a big interfacial stresses and result in premature failure. Therefore, the purposes of this study were to investigate thermal expansion characteristics of latex-modified concrete with cement types. The result of thermal expansion showed the coefficient of thermal expansion of concretes increased with latex inclusion. The coefficient of thermal expansion of RSLMC was a little smaller than that of LMC, which might be due to the finer cement grain, compacter internal, and stiffer properties of concrete. However, the coefficients of LMC and RSLMC were quite similar to that of ordinary cement concrete. Thus, this would not cause an interfacial stresses and will enable to ensure long-term performance of concrete bridge deck overlays.

• 한국농공학회논문집
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• 제49권2호
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• pp.37-46
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• 2007

The service life of agricultural concrete structures is designed in about 30 to 100 years, but actual service lift is estimated in an average 18 years. Therefore, as the service life of the agricultural concrete structures increases, necessity of repair by aging from various environment condition exposure increases. This study was to determinate the optimum mix proportion of latex modified repair mortar and to improve the durability performance of agricultural concrete structures. The physical and mechanical tests of latex modified repair mortar were performed. Tests of flow, compressive strength, flexural strength and bond strength tests were conducted. Test results show that the optimum nex proportion of latex modified repair mortar, when used in 5% latex volume fraction (weight of cement), 1.5% antifoaming agent (weight of latex), 0.2% PVA fiber volume fraction, 1:2 (binder-sand ratio), 10% silica fume replacement ratio (weight of cement), could result in best performance for the repair of agricultural concrete structures.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.647-652
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• 2000

The bond strength of latex-modified concrete to normal portland cement concrete measured with direct pull-out test. Using $250\times1100\times1400$mm concrete slab as the base concrete, an overlay of the latex-modified concrete is applied and cured similar to bridge deck and then tested in direct pull-out. The test results not only give values of the bond strength of the overlay tested but also clearly indicate whether the failure is in the bond interface or the materials tested.