• 한국소음진동공학회논문집
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• 제23권5호
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• pp.414-422
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• 2013

As structure-borne sound, the floor impact sound is one of the serious noises in residential building. Most of heating system applied to the typical Korean residential building is floor heating system which is called ondol. The ondol usually consists of finishing material, mortar with heating coil, light-weight aerated concrete and reinforced concrete. This study focused on the isolation of heavy-weight impact sound and modification of mortar and light-weight aerated concrete. Specifically the glass foam aggregate was added on light-weight aerated concrete. Also, water-cement ratio and amount of cement on mortar were revised. The sound pressure level of heavy-weight impact was measured in reverberation chamber using both bang-machine and impact ball. The size of specimen was 1 m by 1 m. Substitution ratio of glass foam aggregate on light-weight aerated concrete shows relationship with heavy-weight impact sound pressure level. In addition, heavy-weight impact sound pressure level was decreased with increment of water-cement ratio and amount of cement on mortar.

• 콘크리트학회지
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• 제8권5호
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• pp.135-143
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• 1996

콘크리트 및 모르터중의 수분의 확산 거동은 탄성계수, 크리프, 건축수축 등의 역학적 성질에 큰 영향을 미친다. 일반적으로 건조과정에서 폴리머 시멘트 콘크리트와 모르터의 수분의 증발에 의한 중량감소는 내부의 폴리머 필름형성에 의한 보수효과로 보통 시멘트 콘크리트 및 모르터에 비해 월등히 적다. 본 연구는 폴리머 시멘트 모르터 내부의 수분의 확산 과정을 확인하기 위하여 3종류의 폴리머디스퍼션과 에폭시 수지를 사용한 폴리머 시멘트 모르터를 제조하여 건조조건에 따른 수분의 확산 정도를 확산계수로 평가하였다. 실험결과, 폴리머 시멘트 모르터의 수분확산은 보통 시멘트 모르터에 비하여 아주 적었으며 폴리머 시멘트비에 따라 감소하였다.

• 한국세라믹학회지
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• 제44권9호
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• pp.496-501
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• 2007

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. To overcome this problem, polymer-modified cement based on rapid setting cement mortars were prepared by varying polymer/cement mass ratio (P/C) with a constant water/cement mass ratio of 0.5. The effect of polymer on the hydration of this polymer cement is studied on different curing temperature. The results showed that the polymer mortar which is modified with rapid setting cement have superior physical strength properties on independent curing temperature. In addition the PIC ratio, the compressive strength, flexural strength, tensile strength and adhesion strength of mortar is enhances and polymer-modified cement based on rapid setting cement is more beneficial to the improvement of the mortar properties in jobsite.

• 한국세라믹학회지
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• 제26권5호
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• pp.698-704
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• 1989

Basic investigation for the flexural strength and water stability of hardened cement pastes using ordinary portland cement with water-soluble polyer (hydroxypropyl methyl cellulose ; HPMC) was carried out with 0.2 of water cement ratio. For molding of the specimen, the paste was mixed by twin roll mill. According to increase in the content of HPMC, the setting time of cement paste was delayed and the flexural strength was increased. The maximum flexural strength of hardened cement paste with 5.0wt% of HPMC was about 330 kg/$\textrm{cm}^2$. The expansion of the hardened cement paste immersed in water was increased with the content of water soluble polymer(HPMC). Consequently, the strength and the water stability of the hardened cement pastes were remarkably reduced by the expansion of them.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.527-532
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• 2003

When fresh concrete is exposed to sufficiently low temperature, the free water in the concrete is cooled below its freezing point and transforms into ice, which causes decrease in compressive strength of concrete. Of the many influencing factors on the loss of compressive strength, the age of concrete at the beginning of freezing, water-cement ratio, and cement-type are significantly important. The objective of this study is to examine how the these factors affect the compressive strength of concrete frozen at early ages. The results from the tests showed that as age at the beginning of freezing is delayed and water-cement ratio is low, the loss of compressive strength decreases. In addition, concrete made with high-early-strength cement is less susceptible to frost damage than concrete made with ordinary portland cement.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.247-250
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• 2000

As construction technology advances, most of concrete structures are becoming larger and taller. Therefore, high strength and high quality concrete is necessary for them. Nowadays, the proposal of using type IV(belite cement) is investigated to satisfy high flowing, low heat, and ho호 strength. In this study, the flow value and compressive strength of mortar were investigated according to usage of AE high range water reducer. And the slump flow value, falling time and heigth difference of concrete with beilte cement and ordinary cement were examined depending on water cement ratio, sand ratio and unit water weigth, and compressive strength to checked depending on age.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.657-660
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• 2006

Recently, very-early strength latex-modified concrete(below ; VES-LMC) has been developed for repairing and overlaying the old concrete bridge deck. Early-age defects in high-performance concrete due to thermal and autogenous deformation shorten the life cycle of concrete structures. Thus, it is necessary to examine the behavior of early-age concrete at the stages of design and construction. The purpose of this study was to evaluate the autogenous shrinkage of VES-LMC, having an experimental variables such as retarder and water-cement ratio. The greater the retarder content in VES-LMC, the greater the expansion at early-age. This recommend the small retarder content as possible. The effect of water-cement ratio on early-age behavior is very small, because of the wrapped specimen in order to prevent water evaporation.

• 한국건축시공학회지
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• 제17권3호
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• pp.227-234
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• 2017

본 연구에서는 준설토 투기장의 갯벌을 골재의 대체 재료로 사용하여 갯벌의 혼입율, 물-시멘트비의 증가에 따른 모르타르의 특성 및 친환경 건축자재로서의 적용 가능성을 분석하였다. 플로우 실험결과 갯벌 혼입량이 증가할수록 플로우 값이 감소하는 것으로 나타났으며, 염화물함유량시험은 갯벌의 혼입량이 증가함에 따라 염화물함유량이 증가하는 것으로 나타났다. 갯벌을 혼입한 시험체의 압축 및 인장강도시험에서는 갯벌의 혼입율이 증가할수록 강도는 저하되었지만 재령 14일강도 기준으로 대부분의 시험체가 Plain보다 높은 강도를 나타냈으나, 재령 14일의 강도가 재령 28일의 강도보다 높은 값을 발현하였다. 이는 갯벌의 점성과 응집력으로 인한 혼합과정의 실험오차로 판단되며, 추후 갯벌의 혼합방법에 대한 연구가 필요할 것으로 사료된다. 본 실험의 압축강도에서는 물-시멘트비 70%가 가장 우수하였고, 인장강도에서는 물-시멘트비 80%가 가장 우수하였다. 표면분석평가에서는 강도와 배합, 다짐에서 가장 양호한 물-시멘트비 70%를 선정하여 표면의 거칠기를 분석하였는데, 분석결과에서 갯벌의 혼입율이 증가할수록 매끄러운 표면을 나타냈다. 결론적으로 물-시멘트비 70%가 갯벌모르타르의 최적의 혼합비이며 갯벌 혼입율 10~30%가 가장 최적의 비율로 판단된다. 또한 갯벌을 이용한 벽돌, 타일 등의 내부 마감재와 내부 미장바름재 등의 적용이 가능할 것으로 판단된다.

• Computers and Concrete
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• 제7권5호
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• pp.421-435
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• 2010

This paper utilizes the modified Davis model and the mode coupling theory, as parts of the electrolyte solution theory, to investigate the diffusivity of the ion in concrete. Firstly, a computational model of the ion diffusion coefficient, which is associated with ion species, pore solution concentration, concrete mix parameters including water-cement ratio and cement volume fraction, and microstructure parameters such as the porosity and tortuosity, is proposed in the saturated concrete. Secondly, the experiments, on which the chloride diffusion coefficient is measured by the rapid chloride penetration test, have been carried out to investigate the validity of the proposed model. The results indicate that the chloride diffusion coefficient obtained by the proposed model is in agreement with the experimental result. Finally, numerical simulation has been completed to investigate the effects of the porosity, tortuosity, water-cement ratio, cement volume fraction and ion concentration in the pore solution on the ion diffusion coefficients. The results show that the ion diffusion coefficient in concrete increases with the porosity, water-cement ratio and cement volume fraction, while we see a decrease with the increasing of tortuosity. Meanwhile, the ion concentration produces more obvious effects on the diffusivity itself, but has almost no effects on the other ions.

• 한국지반공학회논문집
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• 제33권1호
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• pp.5-15
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• 2017

주면마찰력은 매입말뚝에서 가장 큰 영향 요소이다. 특히 시멘트풀과 지반 사이의 인터페이스 거동에 있어 가장 큰 영향을 미친다. 본 연구에서는 시멘트 풀 영향을 고려하여 단독말뚝에 대한 현장축소모형말뚝 재하시험을 수행하였다. 시험말뚝은 상사비를 고려하여 길이 1.3m 지름 0.067m로 선정하였으며, 굴착공경은 150, 125, 90, 86, 74mm, 시멘트풀 물/시멘트비는 90, 70, 60%로 급속재하시험을 수행하였다. 분석 결과 굴착공경이 증가할수록 지지력 증가를 확인하였다. 또한, 물/시멘트비가 부배합일수록 지지력이 증가하는 것을 확인하였다. 상사비를 고려한 축소모형시험결과, 굴착 공경은 말뚝지름(0.508mm 기준)보다 대략 0.1~0.4D(50~200mm) 크게 시공하는 것이 적합하다. 그리고 시멘트풀 물/시멘트비는 본 연구 결과와 품질관리 등을 고려하였을 때, 70% 정도가 적절하다.