• Structural Engineering and Mechanics
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• 제55권1호
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• pp.137-160
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• 2015

The one-way (two-way) flexural strength of RCC prisms (circular slabs) reinforced with glass fiber textiles is addressed. To this end, alkaline-resistant glass fiber textiles with three surface weights were used in the composite, the matrix concrete was designed with zero/nonzero slump, and the textiles were used with/without an intermediate layer provided by epoxy resin and sand mortar. Prisms were tested under a four-point loading apparatus and circular slabs were placed on simple supports under a central load. Effects of the amount and geometry of reinforcement, matrix workability, and the intermediate layer on the ultimate load and deflection were investigated. Results revealed that, with a specific reinforcement amount, there is an optimum textile tex for each case, depending on the matrix mix design and the presence of intermediate layer. Similar results were obtained in one-way and two-way bending tests.

• 콘크리트학회지
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• 제9권6호
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• pp.195-206
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• 1997

산업폐기물인 폐주물사를 재활용하여 에너지절감과 환경오염방지효과를 얻을 수 있다. 반요인실험법을 사용하여 폐주물사를 잔골재에 일정비율 치환한 콘크리트의 적정배합설계제시를 위한 예비실험에서 물-시멘트비, 폐주물사의 잔골재치환율, 잔골재율, 슬럼프와 같은 주요변수와 변수사이의 2차상호작용을 파악하였다. 예비실험결과 폐주물사의 잔골재치환율 70%까지 실시하였을 때 폐주물사를 혼입한 콘크리트의 강도 발현에 가장 중요한 변수는 물-시멘트비로 분석되었고 폐주물사의 잔골재치환율은 거의 영향이 없는 것으로 분석되어 폐주물사를 콘크리트의 잔골재로 대체할 수 있음을 알 수 있었다. 각 변수의 2차상호작용에서는 폐주물사의 잔골재치환율과 잔골재율의 상관관계가 콘크리트의 강도발현에 가장 큰 영향을 미치는 것으로 나타났다. 목표압축강도에 대한 적정배합조건을 폐주물사의 잔골재 치환율에 따라 물-시멘트비, 잔골재율에 대해 제시하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.123-125
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• 2011

Pre-foaming that has been used in this study is using to control and guarantee quality, but the optimum mix proportion and regulation are not definite. Therefore, this study investigated properties of foamed concrete according to concentrations of foaming agent to improve usability of foamed concrete. Synthetic foaming agent such as AES(Alkyl Ether Sulfate) and AOS(Alpha Olefin Sulfonate) are used to make foam with 1, 3, and 5% concentrations. We found that the flow of foam concrete increases when foam concentration is high and AES is more flowable than AOS. Density and compressive strength increase when foam concentration is low.

• 한국구조물진단유지관리공학회 논문집
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• 제5권3호
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• pp.153-162
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• 2001

This paper presents the fundamental study on rational manufacture of Ultra High Strength(VHS) concrete using industrial by-products as like silica fume, slag and fly ash. In this study, we had tested various mixing cases to manufacture the UHS concrete(target compressive strength : over $1,000kgf/cm^2$) which is easily workable (target slump flow : $60{\pm}10cm$). The main variables are studied: 1) to find the optimum replacement ratio of mineral admixture. 2) to find a rational water-binder ratio and a proper binder content. 3) to find the method for reduction of slump loss. From the test results, it is concluded that the rational mix design can be made by using 40% slag, 10% silica fume. We found that compressive strength of UHS concrete increases according to decreasing W/B ratio but in W/B ratio 18~20%, the difference is vague and the compressive strength does not necessarily increase according to increasing binder content over 700kg.

• 한국농공학회논문집
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• 제52권6호
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• pp.101-110
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• 2010

This study was performed to evaluate the void ratio and strength of porous polymer concrete used coarse aggregates and unsaturated polyester resin to find optimum mix design of porous polymer concrete for planting block. Also, this study was performed to evaluate the planting properties of herbaceous plant and cool-season grass in porous polymer blocks based on the experimental results of porous polymer concrete to develop environmentally friendly planting blocks. Tests for the void ratio and compressive strength of porous polymer concrete were performed at the curing age 7 days. Also, kinds of plants such as Tall fescue, Perennial ryegrass, Lespedeza and Alfalfa for planting were applied to porous polymer blocks. Within 6 weeks after seed, initial germination ratio, cover view and growth length for planting blocks were estimated by various methods.

• Advances in concrete construction
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• 제11권3호
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• pp.207-217
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• 2021

This study relates to a production of Quaternary Cement Concrete (QCC) prepared by using Micro Silica (MS), Marble Dust (MD) and Rice Husk Ash (RHA), followed by an investigation towards fresh and hardened properties of blended concrete. A total of 39 mixes were cast by incorporating different percentages of MS (6%, 7% and 8%), MD (5%, 10% and 15%) and RHA (5%, 10%, 15% and 20%) as partial replacement of Ordinary Portland Cement. The workability of fresh concrete was maintained in the range of 100±25 mm by adding 0.7% of Super Plasticizer in the mix. Optimum mechanical strength was observed at combination of 8% MS+5% MD+10% RHA. Marble dust replacement from 10 to 15% and Rice husk ash replacements from 15 to 20% depicted a substantial reduction in compressive strength at all ages. Durability parameter with respect to water absorption at 28 days shows an increasing trend as the percentage of blending increases.

• 한국건축시공학회지
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• 제13권3호
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• pp.282-290
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• 2013

본 연구는 혼화재의 다량 치환 시 배합 요인의 조정 범위를 검토하기 위한 목적으로 일반 콘크리트에서 혼화재 다량 치환 콘크리트로의 배합변경 데이터를 확보하고자 하였다. 실험결과를 요약하면, 일반 범용적 배합내에서 혼화재 다량 치환 콘크리트로 배합을 변경 시 적정 품질을 확보하기 위한 단위수량의 경우 $20{\sim}30kg/m^3$ 하향 조정, 잔골재율은 W/B 5 % 하향조정 시 약 1 %, 총 치환율 5 % 증가 시약 0.12 %로 중복 하향 조정, AE제는 FA 치환율 5 % 증가 시 컨벤셔널 대비 약 20~30 % 정도 상향 조정, W/B는 FA 및 BS의 치환율이 5 % 상향 시 W/B를 약 1~4 % 정도 하향 조정함으로써 콘크리트의 기본 물성을 확보할 수 있는 것으로 나타났다.

• Advances in concrete construction
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• 제3권4호
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• pp.253-268
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• 2015

This paper investigates the influence of various mix design parameters on the characteristics of concrete containing recycled coarse aggregates and Nano-Silica using Taguchi method. The present study adopts Water-cement ratio, Recycled Coarse Aggregate (%), Maximum cement content and Nano-Silica (%) as factors with each one having three different levels. Using the above mentioned control parameters with levels an Orthogonal Array (OA) matrix experiments of L9 (34) has selected and nine number of concrete mixes has been prepared. Compressive Strength, Split Tensile Strength, Flexural Tensile Strength, Modulus of Elasticity and Non-Destructive parameters are selected as responses. Experimental results are analyzed and the optimum level for each response is predicted. Analysis of 28 days CS depicts that NS (%) is the most significant factor among all factors. Analysis of the tensile strength results indicates that the effect of control factor W/C ratio is ranked one and then NS (%) is ranked two which suggests that W/C ratio and NS (%) have more influence as compared to other two factors. However, the factor that affects the modulus of elasticity most is found to be RCA (%). Finally, validation experiments have been carried out with the optimal mixture of concrete with Nano-Silica for the desired engineering properties of recycled aggregate concrete. Moreover, the comparative study of the predicted and experimental results concludes that errors between both experimental and predicted values are within the permissible limits. This present study highlights the application of Taguchi method as an efficient tool in determining the effects of constituent materials in mix proportioning of concrete.

• 한국안전학회지
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• 제30권3호
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• pp.59-66
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• 2015

본 연구는 슬럼프 감소, 연행 공기 부족, 건조수축 균열, 강도감소 등 굳지 않은 콘크리트와 굳은 콘크리트의 성질에 대한 타설시 고온의 악영향에 대한 원인분석을 실시하고 이를 경감시키기 위한 감수제, 공기연행제, 지연제 등의 화학적 혼화제와 플라이 애쉬, 고로 슬래그 등의 무기질 혼화재의 다양한 적용이 검토되었다. 즉, 서중 콘크리트의 품질향상을 위한 다양한 콘크리트 배합이 설계되고 각 배합에서의 굳지 않은 콘크리트 및 굳은 콘크리트 에 대한 영향이 분석되고 몇 가지의 최적 배합이 도출되었다.

• 한국도로학회논문집
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• 제12권1호
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• pp.87-98
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• 2010

소입경 골재노출 콘크리트포장은 콘크리트 타설 직후 포장표면에 응결지연제를 살포하여 표면으로부터 2~3mm 정도의 모르타르 경화를 늦추게 한 후 표면의 모르타르 제거를 통해 굵은 골재를 포장표면에 노출시키는 공법이다. 소입경 골재노출 콘크리트포장의 타이어-노면 소음은 일반 콘크리트포장보다 작으면서도 적정한 미끄럼저항을 장기간 유지한다는 장점을 가지고 있다. 성공적인 소입경 골재노출 콘크리트포장의 건설을 위해서는 굵은골재의 최대입경이 적정하여야 하며 적정량의 굵은골재를 포장표면에 균일하게 노출하도록 해야 하기 때문에 이를 위한 적절한 배합과 노출기법의 도출이 요구된다. 본 연구에서는 소입경 골재노출 콘크리트포장의 시험시공을 실시하여 초기 공용성을 평가하였으며, 이를 통하여 적정 강도, 저소음 및 적정 미끄럼저항을 확보함을 확인하였다.