• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.603-606
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• 2005

Strength development of low heat portland cement(Type IV) concrete according of addition of fly-ash in high strength range is tested. In this study strength development according to water-binder ratio, strength development according to age, effect of fly ash are tested. This study tests effect of low heat portland cement in high strength range concrete and provide guide line concrete mix design for later study and construction.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 2부
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• pp.31-34
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• 2011

In this study, for the evaluation of field application of low heat concrete using high volume mineral admixture, the characteristics of hydration heat generation and engineering properties of low heat concrete was investigated by mock-up test according to the replacement ratio of mineral admixture. Also, it was evaluated the compressive strength of low heat concrete with curing temperatures and ages for effective concrete mix design considering seasonal change.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.69-72
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• 2005

In this study, it is contents to application on AE water reducing admixture for high early strength, which reduce to construction period for cost down in construction. In experiment result on the kinds of AE water reducing admixture for concrete strength promotion, when passed 60 minutes, while it was happened on lignin and naphthalene system about $30\∼35\%$ that loss related to slump, slump flow and air, but happened about $8\∼10\%$ on polycarboxylic system. And the result of compressive strength tests, when 32 hours passed in polycarboxylic system than lignin and naphthalene system, was showing an increase of 10$\%$. Accordingly, concrete properties was measured to condition change by the addition amount and curing temperature of polycarboxylic system. The required curing temperature to gain 5MPa of compressive strength, which is capable of side form stripping, must keep more than smallest 12. 5$^{circ}C$ when polycarboxylic system is used. As a result, AE water reducing admixture of polycarboxylic system may apply effectively to high early strength concrete

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1991년도 가을 학술발표회 논문집
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• pp.152-157
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• 1991

Expert systems represent the application of artificial intelligence research that is at least 10-15 years old. It may well take another 5-10 years before the present technology is exploited by industry. The objective of this paper is to show the applicability of Combined Hypertext-Expert System Techniques to the professionals working in the construction industry. Expert systems alone don't give the user any control over the system. Hypertext systems that focus only on displaying messages have the opposite problem. While they allow the user to control the system., the only control the system designer has is in setting up the hypertext links. Therefore the combination of these two techniques, offered by KnowledgePro, may bring us closer to real user-expert communication. The system developed in this work offers information on ACI Manual concerning various problem areas in concrete practice, consultation about mix design of concrete and guidance to identify types of cracks in concrete. Once the type of crack is identified through the rule-based knowledge, the system provides the user with remedial measures through the control of the user.

• 한국구조물진단유지관리공학회 논문집
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• 제3권2호
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• pp.155-160
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• 1999

Recently, the study on mix design of lightweight concrete using the polystyrene foam balls is put into practice from the viewpoint to grade up the quality of concrete and recyclable usage of industrial by products. Polystyrene aggregate concrete, PAC, can be used as structural concrete in low strength application. For instance, PAC could be used in the middle part of sandwich panel where stresses are generally low and in the case of grid-type reinforcement where it does not need high bond strength but little compressive strength to resist the pressure of transverse reinforcement. From this point of view, the authors discussed the influence of fluidity and compressive strength of concrete by the difference of the volume percentage of polystyrene foam balls and water cement ratio.

• Computers and Concrete
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• 제30권1호
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• pp.33-42
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• 2022

Experimentally predicting the compressive strength (CS) of concrete (for a mix design) is a time-consuming and laborious process. The present study aims to propose surrogate models based on Support Vector Machine (SVM) and Gaussian Process Regression (GPR) machine learning techniques, which can predict the CS of concrete containing nano-silica. Content of cement, aggregates, nano-silica and its fineness, water-binder ratio, and the days at which strength has to be predicted are the input variables. The efficiency of the models is compared in terms of Correlation Coefficient (CC), Root Mean Square Error (RMSE), Variance Account For (VAF), Nash-Sutcliffe Efficiency (NSE), and RMSE to observation's standard deviation ratio (RSR). It has been observed that the SVM outperforms GPR in predicting the CS of the concrete containing nano-silica.

• 자원리싸이클링
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• 제9권3호
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• pp.37-45
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• 2000

본 논문은 가열 페타이어 재활용 아스팔트 혼합물의 습윤과 동결융해 저항성에 대한 시험결과를 나타내고 있다. 재래식 아스팔트 혼합물과 페타이어 재활용 아스팔트의 기계적 특성을 비교하기 위하여 각기 다른 습윤 조건과 동결 융해 횟수하에서 시험이 수행되었다. 또한, 두 혼합물에 대한 최적 아스팔트 함량을 결정하기 위하여 마샬배합설계가 우선 수행되었다. 본 연구에서 수행된 시험결과에 의하면 페타이어 재활용 아스팔트 혼합물의 습윤과 동결-융해 저항성이 재래식 아스팔트 혼합물보다 우수함을 나타내었다. 따라서 향후 도로포장 재료로의 페타이어 재활용은 습윤과 동결융해로 인한 피해를 최소화할 수 있을 것으로 기대된다.

• Computers and Concrete
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• 제29권 5호
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• pp.347-360
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• 2022

Fiber-reinforced cementitious composites (FRCC) have emerged as a response to the calls for strong, ductile and sustainable concrete mixes. FRCC has shown outstanding mechanical properties and ductility where special fibres are used in the mixes to give it the strength and the ability to exhibit strain hardening. With the possibility of designing the FRCC mixes to include sustainable constituents and by-products materials such as fly ash, FRCC started to emerge as a green alternative as well. To be able to design mixes that achieve these conflicting properties in concrete, there is a need to understand the composition effect on FRCC and optimize these compositions. Therefore, this paper aims to investigate the influence of FRCC compositions on the properties of fresh and hardened of FRCC and then to optimize these mix compositions using factorial design approach. Three factors, water-to-binder ratio (w/b), mineral admixtures (total of fly ash and metakaolin by cement content (MAR)), and metakaolin content (MK), were investigated to determine their effects on the properties of fresh and hardened FRCC. The results show the importance of combining both FA and MK in obtaining a satisfactory fresh and mechanical properties of FRCC. Models were suggested to elucidate the role of the studied factors and a method for optimization was proposed.

• International Journal of Concrete Structures and Materials
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• 제7권3호
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• pp.225-238
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• 2013

In this study, a two-layer feed-forward neural network was constructed and applied to determine a mapping associating mix design and testing factors of cement-nano silica (NS)-rice husk ash ternary blended concrete samples with their performance in conductance to the water absorption properties. To generate data for the neural network model (NNM), a total of 174 field cores from 58 different mixes at three ages were tested in the laboratory for each of percentage, velocity and coefficient of water absorption and mix volumetric properties. The significant factors (six items) that affect the permeability properties of ternary blended concrete were identified by experimental studies which were: (1) percentage of cement; (2) content of rice husk ash; (3) percentage of 15 nm of $SiO_2$ particles; (4) content of NS particles with average size of 80 nm; (5) effect of curing medium and (6) curing time. The mentioned significant factors were then used to define the domain of a neural network which was trained based on the Levenberg-Marquardt back propagation algorithm using Matlab software. Excellent agreement was observed between simulation and laboratory data. It is believed that the novel developed NNM with three outputs will be a useful tool in the study of the permeability properties of ternary blended concrete and its maintenance.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.33-36
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• 2007

In order to select the optimum mix for the required fluidity and strength of mass concrete which is applied to transfer girder and to choose the optimum curing method depending on circumstances through hydration heat analysis of mass concrete, this study examined slump flow, air content and elapsed variation (0, 30, 60, 90) in unhardened concrete properties and reviewed compressive strength characteristics in hardening properties. And hydration heat analysis results through simulation are as follows; 1) Fluidity changes of unhardened concrete showed no significant difference, and those of elapsed variation also showed no difference but a bit of tendency to increase in comparison with the initial properties. 2) The higher the water-binder ratio was, the lower the compressive strength properties were, and the higher the fly ash replacement rate was, the lower the compressive strength development was. 3) In case of $Fc=40N/mm^2$, the optimum mix was fly ash replacement rate of 15% from water-binder ratio of 33.0%. 4) Hydration heat analysis results showed that in case of bundle cast, concrete temperature profile characteristics around transfer girder was unfavorable, and in case of separate cast, constant curing for at least seven days guaranteed thermal cracking index of 1.2.