• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.95-98
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• 2003

This paper presents the results of field experiment to apply the difference of setting tine method using super retarding agent for reducing hydration heat of mass concrete of foundation. According to the results, as the properties of fresh concrete, base concrete satisfies aimed slump and air content, and there is no difference of slump and air content with mixture of super retarding agent. The mixing ratio of super retarding agent is determined for setting time to be retarded by 12 hours in comparison with base concrete, but because the temperature of the air and concrete is low, the difference of setting time is retarded to 24 hours. In man concrete of foundation to which the difference of setting time method is applied, crack by hydration heat is not seen because the lower concrete of super retarding agent generates heat after generation of hydration heat of the upper concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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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 $5{\sim}20%$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.25-26
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• 2018

Various concrete material technologies and new materials have been developed in accordance with the advancement of buildings. As part of these new technologies, light transparent concrete, which was invented by Hungarian architect Aron Losonczi and attracted worldwide attention, has a technique of arranging optical fiber inside concrete and transmitting the light from exterior to concrete to show silhouette inside. However, due to many disadvantages, application to the field was limited and commercialization was not easy. In Korea, Light Emotion Friendly Concrete has been developed for commercialization. In order to solve the degradation of construction performance caused by the arrangement of expensive optical fiber, which is pointed out as a disadvantage of translucent concrete, It converts expensive fiber into low cost acrylic rod, easy to arrange, pre-assembled to form and post-cast. Therefore, this study aims to improve the mechanical properties of LEFC and to derive optimal combination.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.111-116
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• 2003

Instrumentation system in Concrete Face Rockfill Dam(CFRD) can give special attention to the deformation characteristics of the rockfill and behavior of the concrete membrane during construction, reservoir filling and subsequent phase of operation. It also contains data about vertical and transversal compressibility moduli of the rockfill, deflections in the concrete slab, and draws comparisons with other concrete face rockfill dams of recent construction. In this paper, the internal deformation data from D dam monitored by means of hydrostatic settlements cells are analyzed. Observations cover the construction stage, reservoir filling and up to March 1991. The above method can be concluded D dam was well constructed and maintained.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.103-104
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• 2015

This study is an experiment about what affects the compressive strength by using a reducing agent (PNS based admixtures) to play cement using the cement paste based Waste Concrete Powder of waste concrete, which accounts for more than 60% of construction waste around the latest domestic and international It was. Securing the replacement of cement with Waste Concrete Powder and, by varying the admixture was to compensate for the low absorption of liquidity and obtain a fine powder. And the experiment was conducted with a constant water cement ratio and aggregate usage for the purpose of lowering the water cement ratio promoting strength development. When substituted with the experimental results of 0.3% based on 3 ~ 28 days as strength 36Mpa exhibited the highest strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.35-38
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• 2012

Spacers which we have studied is the secondary product of the concrete to apply on concrete structure. It is needed to secure equal or greater performance than structural concrete that it is applied. There is a tendency that concrete structures are strengthened more and more. Therefore, designed set up position of reinforcement is used more and more, so it is needed increasingly high strength spacer. We have been doing a series of research to develop the different typed high strength spacer having crack resistance during constructing. The bearing load of different type spacer shows approximately 35% lower load than those in the general spacers.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.209-210
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• 2012

Cement is an essential material for social infrastructure. Cement production process for cement itself is energy-intensive and requires a large amount of natural resources for fuel and raw materials. This study is to development of recycled cement from waste concrete powder in manufacturing process of recycled aggregate concrete. Recycled cement is low carbon and green growth materials concept for eco friendly construction environment. From the test results, waste concrete powder is same chemical proportion regardless of manufacturing process of recycled aggregate concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.119-124
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• 2005

It is necessary for prediction of recycled aggregate concrete(RAC) strength at the early stage that facilitate concrete form removal and scheduling for construction. However, to predict RAC strength is difficult because of being influenced by complicated many factors. Therefore, this research suggest optimized estimation method that can reflect many factors. One way is Case-Based Reasoning(CBR) that solved new problems by adapting solutions to similar problems solved in the past, which are solved in the case library. Other way is Artificial Neural Networks(ANN) that solved new problems by training using a set of data, which is representative of problem domain. This study is to propose comparing accuracy of the estimating the compressive strength of recycled aggregate concrete using Case-Based Reasoning(CBR) and Artificial Neural Networks(ANN).

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.328-331
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• 2004

Recently, the study for practical construction application of recycled aggregate concrete is actively being proceeded, on the purpose of technical development for recycling on the construction waste concrete occurred at the time of destruction of building construction by the rapid increase of building wastes and exhaustion of natural aggregates. This study is performed to develop the permeable polymer concrete using recycled coarse aggregate and blast furnace slag for application of structures needed permeability. At 7 days of curing, compressive strength, flexural strength, water permeability and flexural load are in the ragge of $18\~20MPa,\;6\~7MPa,\;4.6\times10^{-2}\~6.9\times10^{-2}cm/s$ and $20\~25kN$, respectively. It is concluded that the recycled aggregate can be used in the permeable polymer concretes.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.145-148
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• 2006

Schmidt hammer and ultra-sonic method are commonly used for crushed sand concrete compressive strength test in a construction field. At present, various of equations for prediction of strength are present, which have been used in a construction field. The purpose of this study is to evaluate the correlation between prediction strength by presentation equations and destructive strength to test specimen, and find out which is a suitable equation for the construction site, In this study, a strength test was carried out destructive test by means of core sampling and traditional test. Non-destructive test was conducted Schmidt hammer and ultra-sonic method, the experimental parameter were concrete age, curing condition, test method and strength level. It is demonstrated that the correlation behavior of crushed sand concrete strength in this study good due to the perform analysis of correlation between core, destructive strength and non-destructive strength.