• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.5-10
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• 1992

The aim of this study is to decide the optimum replacement method when mineral Admistures as SILCA FUME and FLY ASH are used, as a part of practical use of ultra High-Strength Concrete. For this purpose, Four types of replacement methods are examined and the relationship between replacement methods and concrete properties is studied. As a result, workability and gain of strength are dependent on the replacement method of mineral Admixtures. The methods of using volumn ratio of cement in FIY ASH, weight ratio of cement in SILCA FUME are shown better workability and strength of concrete than any other replacement method.

• 한국건축시공학회지
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• 제8권2호
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• pp.99-106
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• 2008

To improve concrete tensile strength and bending strength, New plan that have more economical and simple manufacture process is groped. By an alternative plan, chemical pre-stressed concrete is presented. In this study, we analyzed the rheological properties of cement paste with the kind and replacement ratio of k-type CSA type expansive additives that is used mainly in domestic. and we suggested that the algorithm of a mixing plan in the chemical pre-stressed concrete and from this, we presented the basic report for the right mixing plan. From the results, Flow increased more or less according to use of expansive additives. This phenomenon was observed by increasing paste amount that shows as substitution for expansive additives that specific gravity is smaller than that of cement. As linear regression a result supposing paste that mix expansive additives by Bingham plastic fluid. The shear rate and shear stress expressed high interrelationship. therefore, flow analysis of quantitative was available. The plastic viscosity following to replacement ratio of expansive additives is no change almost, the yield value is decreased in proportion to the added amount of expansive additives. Through this experiment, we could evaluate rheological properties of cement paste using the expansive additives. Hereafter by an additional experiment, we must confirm stability assessment of material separation by using the aggregate with the kind and replacement ratio of expansive additives.

• 자원리싸이클링
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• 제33권3호
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• pp.12-20
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• 2024

세계 시멘트 산업의 온실가스 배출량은 약 29억 톤이며, 이중 17.4~18.9억 톤이 시멘트 클링커의 주원료인 석회석으로부터 배출된다. 따라서 비탄산 CaO 원료인 슬래그류 사용이 연구되어야 하며, 이때 시멘트의 물리적 특성도 충분히 발현되어야 한다. 본 연구에서는 슬래그류 사용에 따른 혼합원료 배합 조건과 시멘트 물성을 분석하였다. 슬래그류 단독 사용 시 CaCO₃ 대체율은 한계를 갖으나, 혼합 슬래그 사용 시 CaCO₃ 대체율이 12 % 이상 증가하였다. 단독 슬래그 사용 시멘트의 압축강도는 OPC 대비 감소하였으며, 압축강도 증진을 위해 혼합원료의 LSF 및 시멘트 분말도를 상향시켰다. 분말도 상향 시멘트의 압축강도는 CaCO3₃ 대체율 6 %까지 OPC와 유사하였으나, 9 % 이상에서는 소폭 하락하였다. 하지만 혼합 슬래그 사용 시멘트의 분말도와 LSF를 모두 상향 시, CaCO₃ 대체율 12 % 시멘트도 OPC와 유사한 압축강도가 발현되었다. 또한 CaCO₃ 대체율 12 % 시멘트의 플로우 값도 OPC와 유사하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.77-82
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• 1998

It was investigated to evaluate the characteristics of cement-flyash paste affected the replacement level, curing method and chemical admixtures. The strength of cement-flyash paste was lower than that of cement paste only and the differences increased with increasing the replacement level. However, in steam curing, the strength of cement-flyash pastes was improved and specially, the early strength was effectively increased. In order to improve the early strength, the use of $Na_2SO_4$ in cement-flyash paste increased the quality of concrete. In addition, the strength of concrete including 30% of fly ash has improved and obtained the highest strength compared to other concrete mix.

• Smart Structures and Systems
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• 제24권3호
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• pp.415-425
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• 2019

This study was carried out to evaluate the natural zeolite in producing green concrete as an effort to prevent global warming and environmental impact problems of cement industries. To achieve this target, two types of natural zeolites applied to study physical, chemical and compressive strength of concrete containing different percentages of zeolites. The results in comparison with control samples indicate that compressive strength of zeolites mixes increases with the 15% replacement of zeolite instead of cement in all types of samples. In the water-cement ratio of 0.6, results showed an increase in the compressive strength of all percentages of replacement. This results indicate that using natural zeolites could be produced a green concrete by a huge reduction and saving in the consumption of cement.

• 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.

• 한국건축시공학회지
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• 제5권1호
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• pp.81-88
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• 2005

As a part of efforts for conformity of demand to high quality of concrete and for solution of economic problem, blast-furnace slag has been utilized by means of cement replacement. With utilization of blast-furnace slag, superior performance can be ensured, environmental pollution can be prevented and economical advantage can be obtained. But blast-furnace slag has a lot of disadvantages like retardation of strength manifestation etc. in field construction, so properties examination of concrete using blast-furnace slag instead of cement is necessary. For upper necessity, it is planed that basic data for utilization and performance management of blast-furnace slag by means of cement replacement is presented with experimental comparison and investigation of engineering properties of concrete according to the replacement ratio and fineness of blast-furnace slag.

• Advances in concrete construction
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• 제4권1호
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• pp.49-69
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• 2016

This work investigates the mechanical properties of conventional concrete (CC) and self compacting concrete (SCC) using fine rubber and silpozz were accompanied by a comparative study between conventional rubberized concrete (CRC) and self compacting rubberized concrete (SCRC). Fine rubber (FR) from scrap tires has replaced the fine aggregate (FA) and Silpozz has been used as a replacement of cement at the proportions of 5, 10 and 15%. Silpozz as a partial replacement of cement in addition of superplasticiser (SP) increases the strength of concrete. Fresh concrete properties such as slump test, compaction factor test for CRC, whereas for SCRC slump flow, $T_{500}$, V-funnel, L-box, U-box, J-ring tests were conducted along with the hardened properties tests like compressive, split tensile and flexural strength test at 7, 28 and 90 days of curing. The durability and microstructural behavior for both CRC and SCRC were investigated. FR used in the present study is 4.75 mm passing with fineness modulus 4.74.M30 grade concrete is used with a mix proportion of 1:1.44:2.91 and w/c ratio as 0.43. The results indicate that as FR quantity increases, workability of both CRC and SCRC decreases. The results also show that the replacement of natural fine aggregate (NFA) with FR particles decreases the compressive strength with the increase of flexural strength observed upto 5% replacement of FR. Also replacement of cement with silpozz resulted enhancement of strength in SCRC.

• Computers and Concrete
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• 제11권2호
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• pp.93-104
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• 2013

The use of rock wool waste, an industrial by-product, in cement-based composites has positive effects on the environment because it reduces the problems associated rock wool disposal. The experiments in this study tested cement-based composites using various rock wool waste contents (10, 20, 30 and 40% by weight of cement) as a partial replacement for Portland cement in mortars. The pozzolanic strength activity test, flow test, compressive strength test, dry shrinkage test, absorption test, initial surface absorption test and scanning electron microscope observations were conducted to evaluate the properties of cement-based composites. Test results demonstrate that the pozzolanic strength activity index for rock wool waste specimens is 103% after 91 days. The inclusion of rock wool waste in cement-based composites decreases its dry shrinkage and initial surface absorption, and increases its compressive strength. These improved properties are the result of the dense structure achieved by the filling effect and pozzolanic reactions of the rock wool waste. The addition of 30% and 10% rock wool wastes to cement is the optimal amount based on the results of compressive strength and initial surface absorption for a w/cm of 0.35 and 0.55, respectively. Therefore, it is feasible to utilize rock wool waste as a partial replacement of cement in cement-based composites.

• 한국지반환경공학회 논문집
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• 제15권8호
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• pp.51-58
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• 2014

본 연구에서는 원지반 점토와 시멘트 혼합토를 포함하는 복합지반을 조성하고 이에 대한 실내 일축압축강도 시험을 통해 원지반 점토 함수비 및 치환율, 시멘트 함유율 등에 따른 강도 및 변경 특성치를 분석하였으며, 혼합토에 대한 개별요소 수치모델링을 수행하였다. 시멘트 함유율 15 % 이상에서는 최종적인 복합지반의 강도에 있어 치환율을 증가시키는 것보다 시멘트 함유량 증가 등을 통한 혼합토의 강도를 증가시키는 것이 더욱 유리함을 알 수 있었으며, 회귀분석을 통해 원지반 점성토의 일축압축강도와 시멘트 혼합토의 시멘트 함유율, 복합지반 치환율을 이용하여 최종적인 복합지반의 일축압축강도 및 탄성계수 예측이 가능하였다. 치환율과 함께 최종적인 복합지반의 강도 및 변형 특성치 예측에 가장 중요한 요소인 시멘트 혼합토의 일축압축강도는 실내시험 및 본딩모델이 적용된 3차원 개별요소 수치모델링을 통해 그 검증과 예측이 가능하였다.