• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.55-56
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• 2022

As global warming becomes serious, research is continuously being conducted to reduce CO2 emissions. Among building materials, the carbon emission of cement is so high that it accounts for 6.8% of the carbon emission of the entire industry. Studies replacement of cement with blast furnace slag and fly ash are steadily increasing. In addition, efforts are being made to reduce air pollution due to increased damage caused by increased concentrations of harmful substances such as fine dust and heavy metals in the air. There is an increasing number of studies that enable adsorption by mixing adsorbents into building materials. This study reviewed the strength properties to make an adsorbable non-cement finishing material by mixing tourmaline, an adsorbent, based on the non-cement composite, and confirmed that the strength decreases as the replacement ratio increases.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2014년도 춘계 종합학술대회 논문집
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• pp.71-72
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• 2014

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.154-163
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• 2009

The groutability depends on the properties of the grout, its injection processes, and on the mechanical properties of the soil formation. During the process of pouring cement-based grouting into a porous medium, a variation with time occurs in the viscosity of grout suspension. In addition the particle filtration phenomenon will limit the expansion of the grouted zone because cement particles are progressively stagnant within the soil matrix. In this paper, a closed-form solution was derived by implementing the mass balance equations and the generalized phenomenological filtration law, which can be used to evaluate the deposition of cement-based grout in the soil matrix. The closed-form solution relevant to a particular spherical flow was modified by a step-wise numerical calculation, considering the variable viscosity caused by a chemical reaction, and the decrease in porosity resulting from grout particle deposition in the soil pores. A series of pilot-scale chamber injection tests was performed to verify that the developed step-wise numerical calculation is able to evaluate the injectable volume of grout and the deposition of grout particles. The results of the chamber injection tests concurred well with that of the step-wise numerical calculation. Based on the filtration phenomenon, a new groutability criterion of cement-based grout in a porous medium was proposed, which might facilitate a new insight in the design of the grouting process.

• 한국건설순환자원학회논문집
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• 제12권1호
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• pp.102-109
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• 2024

석회석미분말을 콘크리트용 재료로 활용하기 위하여 치환율을 달리하여 제조한 시멘트 경화체의 역학적 특성 및 내구특성을 평가하였다. 일반적으로 석회석미분말은 시멘트 수화반응에 기여하지 못함으로 이를 사용한 모르타르의 압축강도 시험결과 치환율이 증가할수록 압축강도는 감소하였다. 그러나 석회석미분말을 사용한 모르타르의 염소이온 침투저항성, 탄산화저항성 및 화학저항성 등 내구성능을 평가한 결과 석회석미분말의 작은 입자가 시멘트 경화체 내부의 미세한 공극을 채워주는 마이크로 필러효과로 인하여 치환하지 않은 기준 모르타르에 비하여 우수한 결과를 나타내었다. 따라서 석회석미분말은 콘크리트의 내구성 향상을 위한 효과적인 방법으로 활용될 수 있을 것으로 기대된다. 본 연구에서는 석회석미분말의 치환량을 0 %, 5 %, 10 %, 15 %로 변화시켜 내구성능을 평가하였으나 향후 석회석미분말의 종료와 치환량을 다양한 수준으로 변화시켜 내구성능에 미치는 영향을 보다 자세히 연구할 필요가 있을 것으로 판단된다.

• 한국세라믹학회지
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• 제35권5호
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• pp.421-428
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• 1998

순수 HAC/PVA 계 및 epoxy 수지와 urethane이 첨가된 HAC/PVA 계 MDF 시멘트 복합재료에 서로 다른 관능기를 갖는 3종류의 silane coupling agent를 첨가하여 강도 및 수분안정성에 대한 영향을 살펴보고 기공율 분석을 통해 미세구조와 강도의 관계를 살펴보았다. Silane의 관능기에 따라 각각의 MDF 시멘트 복합재료의 강도 및 수분안정성 향상에 대한 효과가 다른 것을 알 수 있었다. 순수 PVA 메트릭스의 경우에 대해서는 vinyl 기를 갖는 silane이 효과적인 영향을 나타내었으며 epoxy수지가 첨가된 MDF 시멘트에 대해서는 epoxy-methoxy 기를 갖는 silane이, 그리고 urethane이 첨가된 MDF 시멘트에 대해서는 diamine 기의 silane이 효과적이었다. Silane의 첨가량에 따라서는 urethane이 첨가된 MDF 시멘트 복합재료의 경우, diamine 기의 silane이 많이 첨가될수록 수분안정성이 향상되었으며 특히 2wt%의 silane을 첨가하고 wqrm press를 이용하여 성형하였을 때 건조 강도는 약 20% 향상되었으며 습윤강도는 40~70%까지 크게 향상되었다. 이는 기공율과 밀접한 관계가 있음을 알 수 있었다. Epoxy 수지가 첨가된 MDF 시멘트의 경우에서도 2wt%의 silane 첨가까지는 그 첨갈향이 많아질수록 강도가 향상되는 것을 알 수 있었지만 과량의 silane(4wt%)이 첨가될 경우에서는 오히려 특성저하가 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.727-730
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• 2003

The objective of this work is to understand the deterioration mode of ordinary portland cement pastes and mortars immersed in 5% sodium sulfate solution for 510 days. In order to achieve the goal, x-ray diffraction (XRD) and scanning electron microscopy (SEM) are presented in this experimental work. Strength deterioration (SDF) and length change of the mortars were also measured to evaluate resistances to the attacking solution. The mortars were prepared by using water-cement ratio of 35%, 45% and 55%, respectively, and the water-cement ratio of pastes was fixed at 45%. Conclusively, the deterioration by sodium sulfate attack was primarily due to the formation of ettringite and thaumasite. This process of deterioration may submit the reasonable understanding on the sulfate attack mechanism of hardened cement pastes, mortars, and concretes.

• 한국세라믹학회지
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• 제36권12호
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• pp.1342-1349
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• 1999

In order to improve the density and the mechanical strength without change in chemical composition the hardened pastes of hydroxyapatite cement were reinforced with powders and/or whiskers of hydroxyapatite. The powders behaved as a seed of hydroxyapatite formation rather than a filler while the whiskers were mrerly dispersed in matrix and capillary pores of the hardened bodies leading to increase in mechanical strength. But the increase in strength But the increase in strength was nnt enough owing to the lack of homogeneous dispersion of the fibers. The highest diametral tensile strength of 18.5 MPa was measured at the hardened hydroxyapatite body in which well-dispersed whisker phase formed uniformly during hydro-thermal curing of power-added and dry-formed hydroxyapatite cement.

• 콘크리트학회논문집
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• 제29권4호
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• pp.399-406
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• 2017

CaO원 산업부산물은 CaO, $SO_3$ 및 $Al_2O_3$ 등으로 구성되어 있어 CaO 화합물의 원료로 사용되고 있다. 이러한 CaO원 산업부산물을 레미콘 회수수에 적용할 경우 슬러지수의 pH를 높여주어 콘크리트 분말원료의 수화 반응을 촉진 하여 콘크리트 조직을 치밀하게 하여 성능향상이 가능할 것이다. 본 연구에서는 레미콘 회수수에 CaO원 산업부산물 중 하나인 탈황석고를 혼입하여 제조된 활성슬러지의 효과를 확인하기 위하여 시멘트 경화체 및 모르타르의 특성을 분석하였다. 그 결과 시멘트 경화체의 경우 응결시간 단축 및 높은 안정성을 나타내었으며, 기기분석을 통해 수화반응이 촉진되었음을 확인할 수 있었다. 또한 활성 슬러지 제조를 위하여 CaO원으로서 사용된 탈황석고는 단위수량을 조절할 경우 작업성을 확보할 수 있을 뿐만 아니라 적절하게 혼입 될 경우 시멘트 사용량이 줄더라도 높은 강도 발현을 나타내는 것을 확인할 수 있었다.

• 한국세라믹학회지
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• 제55권5호
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• pp.480-491
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• 2018

Calcium phosphates (CaP) were prepared by a wet chemical method. Micro-crystalline dicalcium phosphate (DCPD) was precipitated at $37^{\circ}C$ and pH 5.0 using $Ca(OH)_2$ and $H_3PO_4$. The precipitated DCPD solution was kept at $37^{\circ}C$ for 96 h. Artificial bone cement was composed of DCPD, $Ca(H_2PO_4)_2{\cdot}H_2O$ (MCPM), and $CaSO_4{\cdot}1/2H_2O$, $H_2O$ and aqueous poly-phosphoric acid solution. The wet prepared CaP powder was used as a matrix for the bone cement recipe. With the addition of aqueous poly-phosphoric acid, the cement hardening reaction was started and the CaP bone cement blocks were fabricated for the mechanical strength measurement. For the tested blocks, the mechanical strength was measured using a universal testing machine, and the microstructure phase analysis was done by field emission scanning electron microscopy and X-ray diffraction. The cement hardening reaction occurred through the decomposition and recrystallization of MCPM and $CaSO_4{\cdot}1/2H_2O$ added on the surface of the wet prepared CaP, and this resulted in grain growth in the bone cement block.

• 환경위생공학
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• 제16권2호
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• pp.63-70
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• 2001

This study was initiated to evaluate and resolve the potential problems caused as the MSWI(Municipal Solid Waste Incinerator) fly ash were stabilized and solidified into the cement. The physical and chemical properties of fly ashes (K and M) used in this study were fixed according to the operating conditions of the incineration plant. The compressible strength of the solidified matrix used in this study were measured at 7, 28, and 56 curing days, respectively, to evaluate the stability of the solidified matrix, which were further analyzed by XRD and SEM. The experimental results obtained in this study showed that the relatively long hours of curing periods were needed to solidify the fly ash. The solidified matrix containing K ash had the high and excellent compressible strength of $200{\;}kg/\textrm{cm}^2$, after 56 curing days, but was not good enough in appearance. The analytical data by SEM confirmed that the alkaline Na and K, which are highly dissolved in water, were included in the fly ash and evenly distributed into the exterior surface of the solidified matrix. Whereas, the solidified matrix containing M ash never showed such a compressible strength as shown in the K ash due to the severe fracture, even as early as 7 curing days. Based on its XRD analysis, it appeared that both $C_2S$ and $C_3S$ highly related to the compressible strength were not crystallyzed into the solidified matrix. However, the compressible strength of the solidified and cemented M ash was remarkably improved by 100 times, after the alkalinity was washed out, which indicated that it is equivalent to 30 to 40g per one kg of fly ash.