• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.777-780
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• 2005

The paper presents details of an investigation into the effect of sand content upon the strength and shrinkage of mortar. This strategy was to produces more durable strength mortar with less cement. Cement mortars containing $20\;wt.\;\%$ Class F fly ash, and/or $6\;wt.\;\%$ silica fume were prepared at a water/binder ratio of 0.45 and sand/binder ratios of 2.0, 2.5, 2.7, and 3.0. The increase in sand/binder ratio caused a decrease in the mortar flow. However, the sand/binder ratio did not affect the strength development. Drying shrinkage decreased with increasing the sand contents.

• 콘크리트학회논문집
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• 제21권1호
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• pp.29-35
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• 2009

최근 전 세계적으로 우수한 성능을 인정받는 플라이애쉬는 시멘트의 대체재로 많은 연구와 적용사례가 늘어나고 있으나, KS L 5405에 규정된 분말도 $3,000{\sim}4,500\;cm^2/g$급인 플라이애쉬를 단위시멘트량의 20% 전후로 치환하여 사용하고 있어 그 이상의 분급에 관한 규정은 부족한 실정이다. 따라서, 본 연구에서는 3성분계 콘크리트의 특성에 미치는 고분말도 플라이애쉬의 치환율 및 물-결합재비 영향을 분석하기 위해 분말도 4000, 6000, 8000급과 치환율 15, 30, 45%의 3수준으로 설정하였으며, 물-결합재비는 40, 50%의 2수준으로 실험한 결과, 굳지않은 콘크리트의 성상에서 플라이애쉬의 치환율과 분말도가 높을수록 유동성이 향상되는 경향을 나타내었으나, 물-결합재비가 높을수록 현저히 낮아지는 것으로 나타났다. 또한, 공기량은 플라이애쉬의 치환율과 분말도가 증가하고 물-결합재비가 낮아짐에 따라 감소하는 경향을 나타내었고, 플라이애쉬의 치환율과 분말도가 높을수록 응결이 촉진되는 현상을 나타내었으며, 물-결합재비에 관계없이 플라이애쉬의 치환율이 높을수록 수화열 저감을 확인할 수 있었다. 또한, 강도특성에서는 치환율과 물-결합재비가 높아질수록 강도가 낮아지는 경향을 나타내었다.

• 산업기술연구
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• 제41권1호
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• pp.1-6
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• 2021

Fly ash and silica fume belong to industry by-products that can be used to produce concrete. This study shows the model of a neural network to evaluate the strength development of blended concrete containing fly ash and silica fume. The neural network model has four input parameters, such as fly ash replacement content, silica fume replacement content, water/binder ratio, and ages. Strength is the output variable of neural network. Based on the backpropagation algorithm, the values of elements in the hidden layer of neural network are determined. The number of neurons in the hidden layer is confirmed based on trial calculations. We find (1) neural network can give a reasonable evaluation of the strength development of composite concrete. Neural network can reflect the improvement of strength due to silica fume additions and can consider the reductions of strength as water/binder increases. (2) When the number of neurons in the hidden layer is five, the prediction results show more accuracy than four neurons in the hidden layer. Moreover, five neurons in the hidden layer can reproduce the strength crossover between fly ash concrete and plain concrete. Summarily, the neural network-based model is valuable for design sustainable composite concrete containing silica fume and fly ash.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2003년도 추계정기총회 및 국제심포지엄
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• pp.134-138
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• 2003

이 논문의 목적은 산업부산물인 플라이애쉬의 재활용을 높이기 위해 플라이애쉬를 대량으로 사용한 플라이애쉬 경화체를 제작 하였다. 단위시멘트량의 90%를 플라이애쉬로 대체하여 제작한 이 경화체의 압축강도, 탄성계수 등 기초적인 물성을 파악하여 구조용 건설재료로 실용화하기 위한 기초적 자료를 제시하고자 한다. 물-시멘트비를 변수로 하여 플라이애쉬 경화체의 휨강도를 측정한 결과 물-결합재비, 잔골재율이 증가할수록 파괴에너지가 감소하였다. 이러한 이유는 파괴에너지가 강도의 영향을 크게 받기 때문으로 판단된다. 이번 실험으로 플라이애쉬 경화체의 기초물성은 기존 콘크리트에 많이 접근했음을 알 수 있었다. 하지만 구조용 건설자재로 도입되기 위해서는 건조수축, 크리프, 동결융해 등의 내구성 실험도 계속 수행되어야 할 것이다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.33-34
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• 2019

Malaysia, as a tropical rainforest country, enjoys an abundance of bamboo plant that proliferate throughout the country. The application of geopolymer technology has become a trend and preserve the environment from harm. Fly ash geopolymer concrete has low early strength and requires 24 hours for the concrete to harden. Thus, the presence of calcium and potassium content in bamboo ash could remedy this problem. Besides, there is no research regarding the use of bamboo ash as a binder in geopolymer concrete. Therefore, the presence of bamboo ash could improve the research field with the use of agriculture waste in a building construction. This research aim is to use bamboo ash in the production of fly ash geopolymer concrete. The specimens were casted in $100mm{\times}100mm{\times}100mm$ cubes and sodium based activator were used as the alkaline solutions. The binders are formulated with different binder ratio. All test specimens were cured at ambient temperature ($23^{\circ}C-25^{\circ}C$) and 100% fly ash was chosen as control specimen. To determine the mechanical properties of fly sh geopolymer concrete with the presence of bamboo ash, compressive strength test was conducted. The test results depicted that as the percentage of bamboo ash decreases, compressive strength increases. Also, the addition of 5% of bamboo ash into fly ash geopolymer concrete could improve the early strength in 7 days. The results were proven with the result explained by X-ray fluorescence (XRF) and X-ray diffraction (XRD). Therefore, it can be concluded that the addition of bamboo ash improved the properties of fly ash geopolymer concrete at early ages.

• International Journal of Concrete Structures and Materials
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• 제7권3호
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• pp.193-202
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• 2013

Geopolymer mortar compressed blocks were prepared using fly ash, ground granulated blast furnace slag, silica fume and metakaolin as binders and sand/quarry dust/pond ash as fine aggregate. Alkaline solution was used to activate the source materials for synthesizing the geopolymer mortar. Fresh mortar was used to obtain the compressed blocks. The strength development with reference to different parameters was studied. The different parameters considered were fineness of fly ash, binder components, type of fine aggregate, molarity of alkaline solution, age of specimen, fluid-to-binder ratio, binder-to-aggregate ratio, degree of saturation, etc. The compressed blocks were tested for compression at different ages. It was observed that some of the blocks attained considerable strength within 24 h under ambient conditions. The cardinal aim was to analyze the experimental data generated to formulate a phenomenological model to arrive at the combinations of the ingredients to produce geopolymer blocks to meet the strength development desired at the specified age. The strength data was analyzed within the framework of generalized Abrams' law. It was interesting to note that the law was applicable to the analysis of strength development of partially saturated compressed blocks when the degree of saturation was maintained constant. The validity of phenomenological model was examined with an independent set of experimental data. The blocks can replace the traditional masonry blocks with many advantages.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.89-92
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• 2006

To investigate the properties of high flowing and high strength concrete with crushed sand and fly ash for CFT structure, many batches were performed by a trial-error method. In the experiment W/B was set up three levels as 0.25, 0.30 and 0.35. Also the variables of the experiment were a substitution ratio of fly ash, a blend ratio of crushed sand and the ages of specimens(3, 7, 28 days). The results of this study are summarized as the follows; 1) The effect a substitution ratio of fly ash on the compressive strength was not consistent with age. For twenty-eight day compressive strength, the best result was come out when cement was substituted by 10% of fly ash. 2) The decrease of the water binder ratio, the increase of compressive strength and elastic modulus. Also the relationship is very similar to the case of a normal concrete

• 한국환경과학회지
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• 제19권1호
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• pp.105-114
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• 2010

The objective of the paper is to experimentally investigate the compressive strength of the concrete incorporating fly ash. Ordinary Portland cement(OPC). Water to binder ratio(W/B) ranging from 30% to 60% and curing temperature ranging from $-10^{\circ}{\sim}65^{\circ}C$ were also adopted for experimental parameters. Fly ash was replaced by 30% of cement contents. According to the results, strength development of concrete contained with fly ash is lower than that of plain concrete in low temperature at early age and maturity. In high curing temperature, the concrete with fly ash has higher strength development than that of low temperature regardless of the elapse of age and maturity. Fly ash can have much effect on the strength development of concrete at the condition of mass concrete, hot weather concreting and the concrete products for the steam curing.

• 콘크리트학회논문집
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• 제23권1호
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• pp.99-107
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• 2011

이 연구는 대용량 지상식 LNG 저장탱크에 사용할 고강도 자기충전 콘크리트의 최적배합 조건을 도출하고, 현장적용을 위한 기본 자료를 제안하기 위한 것이다. 60~80 MPa 고강도 자기충전 콘크리트를 적용하면, 벽체두께의 감소와 자기충전성에 따른 인력절감 및 품질확보 등을 통하여 경제성을 확보할 것으로 예상된다. 시멘트 및 분체는 점성 증대 및 수화열 저감에 우수한 플라이애쉬와 저열 시멘트(벨라이트)를 사용하였다. 플라이애쉬의 치환율은 구속수비 및 배합변수 실험을 통해 정하였으며, 배합변수는 단위수량(W), 플라이애쉬 치환율(FA), 물-결합재비(W/B) 및 잔골재율(S/a)로 하여, 최적배합비 및 경제성 평가를 실시하였다. 실험 결과, 설계기준강도 60 MPa의 경우에는 단위수량 165 $kg/m^3$, 플라이애쉬 치환율 20% 및 물-결합재비 27~30%로 나타났으며, 설계기준강도 80 MPa의 경우에는 단위수량 165 $kg/m^3$, 플라이애쉬 치환율 10% 및 물-결합재비 25%로 나타났다. 또한, 기존의 설계기준강도 40 MPa과 비교해 볼 때, 압축강도 증가에 따른 재료비 상승은 60 MPa의 경우 14~22% 및 80 MPa의 경우 33%로 나타나, 현장관리 및 인력절감 등과 함께 매우 경제적인 것으로 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.3-8
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• 1998

This research is to examine the relationships between viscosity and fluidity according to binders in the super flowing concrete. And this research is described with respect to rheology concept, confined water ratio($\beta_p$) of binders in paste and mortar, also investigated experimentally the relationships between the relative flowing ratio ($\Gamma_m$) and the funneling velocity ratio($R_m$) on the mortar state according to the water binder ratio(W/B) and the dosage of the superplasticizer. From the confined water ratio tests, it is found that $\beta_p$ of the class C fly ash is higher than that of the class F fly and limestone in paste and mortar, therefore class F fly ash and limestone and super flowing concrete. The result of test, the optimum mix condition to the compactibility if satisfied when the replacement ratio is 30% and $K_p$ is 0.8 for the case of fly ash and limestone.