• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.549-554
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• 2002

In Powder System, SCC demands high dosage of superplasticizer and a lage amout of powder for suitable fluidity and viscosity. Okamura's method of most representative mixing design method in SCC of Powder-System is unfavorable economically because of using a large amount of powder. In addition, many ready-mixed concrete plants do not use his mix design method and procedure due to complexity for practical application. Therefore, Nan Su proposed more simple mix design method than Okamura's. It had an advantage in simplicity in practical application and required a smaller amount of powders compared with Okamura's method. This paper proposed an optimal mixture proportion of SCC with consideration of Nan Su's method. The new and modified mix design method required a smaller amount of powder than that of Nan Su's. To check the properties of SCC, considered with the requirements specified by the Japanese Society of Civil Engineering.(JSCE)

• 기술사
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• 제30권6호
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• pp.113-120
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• 1997

This subject,'S" apartment structural frame has not been achieved without considerable effort by all quality controller involved. Therefore, it is appropriate at this time to report by all the fact of concrete quality control in our site. These are emphasized that the average strength of placed concrete must always exceed the specified value of design strength used in the structural design phase. In general, quality of ready mixed concrete largely depends not only upon the manner of production and proper observance of recognized methods of placement, finishing, curing, transportation etc. ,but also many kinds of influential factors even more handling of the test procedure, As this practical report, approaching to judgement by analysis of sampled specimens in site weather placed concrete have satisfied quality compare the specified strength with the target strength which is applied to standard deviation related with influential factors as above mentioned. This case study is consist of 1) A foreword, 2) Site brief, 3) A precondition for analysis, 4) A formulas derivation and quality analysis, 5) Economic gains by the coefRcient of increase and 6) A conclusion.sion.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.427-430
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• 2005

The purpose of this study is to choose the right chemical admixture to reduce slump loss of lightweight aggregate concrete. So we compare 3 types of chemical admixture as measuring slump loss from mixing to 60 minutes. The lightweight aggregate of this study is made by clayt and dust from lots of industry. To save natures, we will use many types of industrial wastes and try to spend much making artificial aggregate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.109-112
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• 2005

As civilization progresses amount of sewage sludge continues to increase from a sewage disposal plant with a huge expenditure of water resources. So It is necessary to reduce the high costs of sewage disposal and the pollution of the environment and also a unit cost of artificial lightweight aggregate by continual recycling. The purpose of this study is to put artificial lightweight aggregate concrete to practical use by using sewage sludge and clay

• 한국건설순환자원학회지
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• 제13권4호
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• pp.33-41
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• 2018

• Computers and Concrete
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• 제4권4호
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• pp.299-316
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• 2007

The compressive strength of concrete is a commonly used criterion in producing concrete. However, the test on the compressive strength is complicated and time-consuming. More importantly, since the test is usually performed 28 days after the placement of the concrete at the construction site, it is too late to make improvements if unsatisfactory test results are incurred. Therefore, an accurate and practical strength estimation method that can be used before the placement of concrete is highly desirable. In this study, the estimation of the concrete strength is performed using support vector regression (SVR) based on the mix proportion data from two ready-mixed concrete companies. The estimation performance of the SVR is then compared with that of neural network (NN). The SVR method has been found to be very efficient in estimation accuracy as well as computation time, and very practical in terms of training rather than the explicit regression analyses and the NN techniques.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.23-26
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• 2006

The study about the concrete to use recently a light weight aggregate, processed actively. And concrete pumping with a high pressure pump has been popularized, the mechanical development, such as high pressure pumps or pipes, is progressing rapidly. Concrete placing by pumping has the advantage of the reduction of the construction period with workability, easiness of work and the increase of placing, but the quality variation of concrete is caused by pumping is seldom considered, including the increase of the pipe length by high-rising and large-sizing, there by the loss of the unit quantity of water, with pumpability or workability deteriorated. In this research, we will compare and analyze before pumping and after pumping samples of ready-mixed light weight concrete. The result of study as follow. The case of a light weight concrete which the low slump is more decrement compared with high slump light weight concrete in after pumping samples. After pumping the water by pressure of a pump was absorbed to the aggregate inside, and it showed an increase of compression strength about $5{\sim}20%$.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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• pp.21-24
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• 2006

This study investigates field application of flowing concrete in order to improve workability, duality and economic evaluation of concrete. Test results showed that slump of fresh concrete satisfied the target value before and after flowing concrete, and setting time indicated 3 hours difference depending on the mixture proportion of ready-mixed-concrete company. As for the hardened concrete, compressive strength of standard curing specimens, both control and flowing concrete, presented designed value at 28 days elapse. However, the specimens curing at atmosphere decreased the value, due to the lower curing temperature, but also performed the designed value at 91 days. For the evaluation of construction fee by value engineering(V.E) concept, a flowing method declined 4.89% of concrete construction fee, which is 4.9% reduction for materials and 25% reduction for labor expenses, compared with previous construction methods.

• KIEAE Journal
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• 제9권1호
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• pp.91-97
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• 2009

In this thesis presents the application to the field of Hwangto-used concrete highlighted as an eco-friendly material and performs an experiment in the aspect of construction and quality on the construction for all parts of buildings, rather than for some parts of buildings as shown from existing application and got the conclusion as followings. 1) It was turned out that Hwangto concrete showed lower hydrated heat and arid contraction comparing to those of cement concrete. And this phenomenon is judged to appear high when applied to mass building and huge span structures. 2) The construction of Hwangto concrete is judged to be possible in applying to constructions since the mechanical construction seems to be possible by using pump car and ready-mixed concrete which are used at the practical sites at the moment. 3) The pockmarks appearing on the exposure surface were about 2% of total area. This has great cohesion by Hwangto concrete but is judged that it will be improved through enough vibration stamping. Through the experiments of quality and construction of Hwangto concrete as environment-friendly construction materials, it is possible to judge modernized application of Hwangto concrete. It is in need of more studies about economical efficiency, structural stability, design application, etc. afterwards.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.50-53
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• 1992

The damages due to alkali-aggregate reaction between the reactive silicia constituents of the aggregate and the alkalies in cement have been frequently reported since 1923 in America . Recently alkali-aggregate reaction, especially alkali-silica reaction, can be found all over the area using crushed stones. The first research, in 1990, was performed to identify the alkali-silica reactivity of 18 sets of crushed stones used in domestic ready-mixed concrete plant as coarse aggregates by 4 petrollgical, chemical and mortar bar method, And the study was continued with 10 sets of crushed stones in this research. It was found that all the aggregates used in this study are innocuous at alkali-silica reaction.