• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.437-440
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• 2005

The effects of polymer-cement ratio and recycled aggregate content on the continuous void ratio, coefficient of permeablity, compressvie, tensile and flexural strengths of water-permeable polymer-modified concretes using recycled aggregate are examined. As a result, the continuous void ratio and coefficient of permeablity of the water-permeable polymer-modified concretes tend to decrease with increasing polymer-binder ratio. Regardless of the recycled aggregate content, the compressvie, tensile and flexural strengths of the water-permeable polymer-modified concretes wtend to increase with increasing polymer-cement ratio.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.186-187
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• 2022

The purpose of this study was to give fluidizing properties to non-sirtered cement made using by-products that can replace Portland cement by using a fluidizing agent. Blast furnace slag, C-type fly ash, and F-type fly ash were used for non-sirtered cement, and sand was used for aggregate. The amount of fluidizing agent used was fixed at 1%, and the water-cement ratio (W/C) was different by setting the binder blending ratio of the non-sintered cement differently, and the fluidity test and flow were compared. As a result of the experiment, when the flow standard was 170mm when the fluidizing agent was used, the fluidizing properties were shown at an average water-cement ratio (W/C) of 36%. Through this study, it was confirmed that the fluidizing properties appeared when the fluidizing agent was used in non-sintered cement.

• 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.

• 한국세라믹학회지
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• 제45권11호
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• pp.744-749
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• 2008

The properties of the polymer-modified mortars are influenced by the polymer film, cement hydrates and the combined structure between the organic and inorganic phases. Also, this quality of polymer modified cement strongly depend on weather condition and polymer cement ratio. To overcome this problem, polymer-modified cement were prepared by varying polymer/cement mass ratio (P/C) with $0{\sim}20%$ and constant water/cement mass ratio of 0.5. The effect of polymer on the hydration of this polymer cement is studied on different polymer cement ratio. The results showed that the polymer cement paste have increased the viscosity in addition the amount of polymer dosage and the polymers is completed resulting in a reduced degree of hydration caused by different ion elution amount. Also we know that the reactants is calcium acetate as a results of chemical reaction between acetate group in EVA which is hydrolysis in water and $Ca^{2+}$ ion during hydration of cement.

• 한국농공학회지
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• 제43권6호
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• pp.135-142
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• 2001

Laboratory experiment was performed to evaluate the influence of mixing conditions to the strength of solidified sandy soils with cement. The major physical factors considered in this experiment were the fine particles content(<$\sharp200%$), cement content(%) and water-cement ratio, and unconfined compressive strength test was performed on the samples at 7 and 28 cured day. The results of tests shows that when the cement content is relatively low (7~10 percents) the fine content in the sandy soils is very important, but when cement content is high the water-cement ratio became more important. It was appeared that in the range of the cement content of 7~10 percents, about 20~30 percents of fine content to the total sample weight is the optimum condition to get the maximum strength. In the case of the cement content of 13 percents, the strength of sample was considerably affected by the water-cement ratio rather than the fine content. In this paper, empirical equations were also developed and evaluated to verify the relationship among three factors by the multi-regression analysis.

• 콘크리트학회논문집
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• 제13권3호
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• pp.237-243
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• 2001

본 논문에서는 플라이애시 콘크리트의 재령에 따른 변화를 예측하기 위한 모델식을 제시하고 그 모델식의 유효성을 검토하였다. 기존에 행해졌던 실험결과를 모델식을 이용하여 회귀분석한 후에 그 결과를 플라이애시 대체량과 물-시멘트비에 따라 분석하였다. 해석결과에 의하면 예측 모델식은 실험결과를 일정오차내에서 잘 모델링하였다. 그러나 물-시멘트비가 매우 작은 경우에는 플라이애시 대체량이 증가하면 실험값과 예측값의 오차가 조금 증가하는 경향을 나타내었다. 플라이애시 대체량이 증가할수록 한계상대압축강도의 크기가 증가하였고 초기 겉보기 활성에너지도 한계상대압축강도와 같이 플라이애시 대체량이 증가할수록 증가하였다. 0.40이하의 물-시멘트비에서는 한계상대압축강도와 겉보기 활성에너지의 크기가 일정하고 물-시멘트비가 0.40을 초과하면 물-시멘트비의 증가에 따라 한계상대압축강도와 겉보기 활성에너지가 조금씩 증가하였다.

• 콘크리트학회논문집
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• 제12권5호
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• pp.25-34
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• 2000

When concrete is placed underwater, it is diluted with separating cementitious material and as a result the quality of concrete becomes poor. To solve this problem, antiwashout underwater concrete is increasingly used for the construction and repair of the concrete structure underwater. The objective of this study is to investigate the characteristics of antiwashout underwater concrete as to the mix proportion, casting and curing water through experimental researches. The unit weight of water and cement, water-cement ratio, fine aggregate ratio, unit weight of antiwashout underwater agent and superplasticizer, and casting and curing water were chosen to measure the suspended solids, pH, air contents, slump flow, unit weight of hardened concrete, and compressive strength. From this study, the incremental modulus at mix proportion design and unit weight of antiwashout underwater agent were increased more than fresh water, and it is a optimum mix proportion that the unit weight of water(and cement) is 230kg/$\textrm{m}^3$(460kg/$\textrm{m}^3$), waterOcement ratio is 50%, fine aggregate ratio is 40%, unit weight of antiwashout underwater agent is 1.2% of water contents per unit weight of concrete, and unit weight of supeplasticizer is 2.5% of cement contents per unit weight of concrete when the antiwashout underwater concrete is used for the underwater work of ocean.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.463-471
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• 2009

Cemented soils or concrete are usually cured under moisture conditions and their strength increases with curing time. An insufficient supply of water to cemented soils can contribute to hydration process during curing, which results in the variation of bonding strength of cemented soils. In this study, by the consideration of in situ water supply conditions, cemented sand with cement ratio less than 20% was prepared by air dry, wrapped, and underwater conditions. A series of unconfined compression tests were carried out to evaluate the effect of curing conditions on the strength of cemented soils. The strength of air dry curing specimen was higher than those of wrapped cured specimen when cement ratio was less than 10%, whereas it was lower when cement ratio was greater than 10%. Regardless of cement ratio, air dry cured specimens were stronger than underwater cured specimens. A strength increase ratio with cement ratio was calculated based on the strength of 4% cemented specimen. The strength increase ratio of air dry cured specimen was lowest and that of wrapped and underwater cured ones increased by square. Strength of air dry cured specimen dropped to maximum 30% after wetting when cement ratio was low. However, regardless of cement ratio, strength of wrapped specimens dropped to an average 10% after wetting.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.124-129
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• 1995

In this study proposed to rapid and simple methid of test for early evaluation of strength of cement. The obtained results through a series of experiment are summarized as follow. The resistance ratio was decreased as the increase of water-cement ratio. The compressive strength of cement was increased as the resistance ratio increase. The experimental results of compressive strength of cement is shown in the same value no relation with the kind of cement respectively.

• 한국환경과학회지
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• 제20권1호
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• pp.71-79
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• 2011

In this study, a series of soil concrete mixtures were tested for the compressive strength according to ratio of aggregate to binder, compaction energy, maximum aggregate size, ratio of silica fume to cement, and ratio of water to binder. The optimum mixing ratio of soil concrete mixtures composed of volcaniclastic, cement, silica fume, concrete polymer and water were analysed. The test results for optimum proportion were as follows ; (1)ratio of aggregate to binder was 4 : 1, (2)compaction energy level was level 2, (3)maximum aggregate size was 13 mm, (4)ratio of silica fume to cement was 10%, (5)ratio of water to binder was 25%. Also, dry type construction techniques were applied using the optimum soil concrete mixture. From the results of this study, the compressive strength of soil concrete and construction techniques were suitable for making eco-friendly soil pavement.