• Advances in concrete construction
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• 제5권3호
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• pp.289-301
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• 2017

The synergistic interactions of supplementary cementitious materials (SCMs) with ordinary portland cement (OPC) in multi-blended systems could enhance the mechanical and durability properties of concrete and increase the amount of cement that can be replaced. In this study, the characteristics of the hydration products as well as paste microstructure of blended cement containing 20% coal fly ash, 10% rice hull ash and 10% sugar mill lime sludge in quaternary blended system was investigated. Portlandite content, hydration products, compressive strength, pore size distribution and microstructural architecture of hydrated blended cement pastes were examined. The quaternary blended cement paste showed lower compressive strength, reduced amount of Portlandite phases, and higher porosity compared to plain hardened cement paste. The interaction of SCMs with OPC influenced the hydration products, resulting to the formation of ettringite and monocarboaluminate phases. The blended cement paste also showed extensive calcium silicate hydrates and calcium aluminate silicate hydrates but unrefined compared to plain cement paste. In overall, the expected synergistic reaction was significantly hindered due to the low quality of supplementary cementitious materials used. Hence, pre-treatments of SCMs must be considered to enhance their reactivity as good quality SCMs can become limited in the future.

• 한국건축시공학회지
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• 제19권3호
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• pp.219-228
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• 2019

본 연구의 목적은 저점도형 고성능 감수제가 혼화재료를 포함하는 시멘트 계열 재료의 유동성 및 레올로지 특성에 미치는 영향을 분석하여 기초적인 정보를 제공하는 것이다. 이에 플라이애시, 고로슬래그, 실리카흄을 치환한 시멘트 페이스트와 모르타르에 대하여 일반적인 고성능 감수제와 저점도형 고성능 감수제를 사용하여 실험을 실시하였다. 실험 결과 저점도형 고성능 감수제는 소성점도에 있어서 일반형 고성능 감수제보다 크게 저감시키는 것으로 나타났다. 이러한 결과를 바탕으로 본 연구가 향후 저점도형 고성능 감수제를 사용하는 데에 기초적인 데이터를 제공할 것으로 기대한다.

• 한국건설순환자원학회논문집
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• 제5권2호
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• pp.137-143
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• 2017

기존의 경우 콘크리트 내구성에 관한 연구는 다양하게 많은 량이 진행된바 있다. 특히 화학적 침식에 관한 연구로는 산 알칼리, 황산염에 대한 침식저항성의 연구가 활발히 진행되었다. 하지만 유지류에 관한 연구로, 특히 각종 유지류의 종류가 혼화재 치환 모르타르에 어떠한 영향을 미치는지에 관해서는 거의 연구되지 않았다. 따라서 본 연구에서는 FA 및 BS의 혼화재 치환 시멘트 모르타르가 각종 유지류에 침지될 경우 나타나는 열화특성에 관하여 연구하였다. 실험결과 유지류 종류 중에서는 지방산 함유량이 높을수록, 특히 BD(바이오디젤)의 경우가 모든 혼화재 치환 시멘트 모르타르의 열화를 가장 크게 일으키는 것으로 나타났고, 혼화재 치환을 한 모르타르의 경우는 OPC(보통포틀랜드시멘트)보다 BS 및 FA치환 모르타르의 경우에서 열화가 더 크게 나타나는 것을 알 수 있었다.

• Advances in concrete construction
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• 제16권6호
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• pp.303-316
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• 2023

Using industrial wastes and construction and demolition (C&D) wastes is potentially advantageous for concrete production in terms of sustainability improvement. In this paper, a sustainable Self-Compacting Concrete (SCC) made with industrial wastes and C&D wastes was proposed by considerably replacing natural counterparts with recycled coarse aggregates (RCAs) and supplementary cementitious materials (SCMs) (i.e., Fly ash (FA), ground granulated blast furnace slag (GGBS) and silica fume (SF)). A total of 12 SCC mixes with various RCAs and different combination SCMs were prepared, which comprise binary, ternary and quaternary mixes. The mechanical properties in terms of compressive strength and static elasticity modulus of recycled aggregates (RA-SCC) mixes were determined and analyzed. Microstructural study was implemented to analyze the reason of improvement on mechanical properties. By means of life cycle assessment (LCA) method, the environmental impacts of RA-SCC with various RCAs and SCMs were quantified, analyzed and compared in the system boundary of "cradle-to-gate". In addition, the comparison of LCA results with respect to mechanical properties was conducted. The results demonstrate that the addition of proposed combination SCMs leads to significant improvement in mechanical properties of quaternary RA-SCC mixes with FA, GGBS and SF. Furthermore, quaternary RA-SCC mixes emit lowest environmental burdens without compromising mechanical properties. Thus, using the combination of FA, GGBS and SF as cement substitution to manufacture RA-SCC significantly improves the sustainability of SCC by minimizing the depletion of cement and non-renewable natural resources.

• Advances in concrete construction
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• 제11권5호
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• pp.419-428
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• 2021

The pH of cement-based materials (CBMs) is an important factor for their durability, sustainability, and long service life. Currently, the use of supplementary cementitious materials (SCMs) is becoming mandatory due to economic, environmental, and sustainable issues. There is a decreasing trend in pH of CBMs due to incorporation of SCMs. The determination of numerical values of pH is very important for various low and high volume SCMs blended cement mortars for the better understanding of different defects and durability issues during their service life. In addition, the effect of cement hydration and pozzolanic reaction of SCMs on the pH should be determined at initial and later ages. In this study, the effect of low and high-volume fly ash (FA) and ground granulated ballast furnace slag (GGBFS) cement mortars in different curing conditions on their pH values has been determined. Thermal gravimetric analysis (TGA) was carried out to support the findings from pH measurements. In addition, thermal conductivity (k-value) and strength activity indices of these cement mortars were discussed. The results showed that pH values of all blended cement mortars were less than ordinary Portland cement (OPC) mortar in all curing conditions used. There was a decreasing tendency in pH of all mortars with passage of time. In addition, the pH of cement mortars was not only dependent on the quantity of Ca(OH)₂. The effect of adding SCMs on the pH value of cement mortar should be monitored and measured for both short and long terms.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.127-128
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• 2022

In order to realize carbon neutrality in the international society, research on supplementary cementitious materials(SCMs) has been actively conducted as a way to reduce carbon dioxide emissions in the cement industry. However, the use of SCMs causes problems of initial hydration delay and strength reduction due to the reduction of tricalcium silicate(C3S) in the cement clinker. Therefore, in this study, the initial hydration and basic characteristics of cement mortar were confirmed by adding a C-S-H based hardening acceleration to blended cement mixed with Portland cement, blast furnace slag, fly ash, and limestone power. As a result of the heat of hydration and compressive strength test, it was confirmed that when hardening acceleration was added, the initial reactivity was high, so the heat of hydration was promoted, and the initial strength was increased. It is considered to be due to C-S-H seeding effect. Therefore, it is judged that the use of C-S-H based hardening acceleration can supplement the problem of initial hydration delay of blended cement in Korea.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.19-20
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• 2022

Portland Limestone Cement (PLC) is a blended cement using limestone powder as SCMs (Supplementary Cementitious Materials), and is currently regarded as an essential means for achieving carbon neutral in the cement industry. This study was performed to investigate the fresh and hardened properties of cement mortar according to the fineness and replacement ratio of limestone powder. As a result, the compressive strength of mortar used high blaine limestone powder were equivalent level of that of OPC.

• Advances in concrete construction
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• 제10권5호
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• pp.417-429
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• 2020

Waste glass is a global solid waste with huge reserves. The discarded waste glass has caused a series of problems such as resource waste and environmental pollution, so it is urgent to recycle waste glass with high replacement level. Glass powder (GP), as a supplementary cementitious material (SCM), used in cement-based materials has already become one of the important ways to recycle waste glass mainly attributed to its pozzolanic reaction and filling effect, especially to the suppressed ASR expansion. This paper demonstrates an overview of the properties of GP and its effect on the fresh and mechanical properties of cement-based materials. The study found that the influence of GP on the performance of cement-based materials mainly depends on its content, particle size, color and type, curing conditions, and other SCMs. Finally, based on the problems involved in the investigation of concrete containing GP, some corresponding suggestions and efforts are given to further guide the utilization of GP in cement-based materials.

• 대한건축학회논문집:구조계
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• 제35권12호
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• pp.165-172
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• 2019

본 연구는 물결합재비 40 %인 일반강도 영역에서 FA, BS 및 FA+BS인 광물질 혼화재의 0~30 %의 치환율 변화가 분체계 고유동 콘크리트의 재료분리 저항성 등 제반 특성에 미치는 영향에 대하여 분석하였다. 특히 고유동 콘크리트에서 밀도가 작은 분체의 치환율을 증가시킬 경우 액상 콘크리트의 점성저하로 재료분리가 증대될 수 있지 않은지, 또한 J-ring시험으로 철근 장애부에 의한 재료분리 정도에는 영향을 미치지 않을지 등 제반특성을 검토 분석하였다. 실험연구 결과 Normal 시험의 경우는 기존의 이론과 같이 광물질 혼화재의 치환율이 증가할수록 레올로지적 측면의 점성증가로 재료분리가 방지되었다. 단, J-ring를 이용한 시험의 경우는 액상중 밀도저하로 양호하게 골재를 끌고 철근사이를 통과하지 못해 재료분리 방지에 큰 역할을 하지 못함을 알 수 있었다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 추계 학술논문 발표대회
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• pp.46-47
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• 2018

High performance concrete with low water-to-cement ratio has been widely used with increased demand of high rising buildings and huge scaled structures. Additionally, for high performance concrete, various SCMs are replaced to improve its performance from fresh state to hardened state. With the drawback of increased viscosity of the concrete mixture for high performance concrete, low-viscosity typed high range water reducer is the relatively new admixture. Therefore, as a goal of the research, under using various SCMs with wide range of content, the performance of low-viscosity typed high range water reducer was evaluated. Especially, in this research, the influence of low-viscosity typed high range water reducer on rheological properties including plastic viscosity and yield stress were assessed. As a result of the research, it is expected to provide a fundamental information of low -viscosity typed high ranged water reducer on high performance concrete with various conditions of SCMs.