• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.99-104
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• 1992

There is a limit manufacturing precast products for the construction industry using conventional cement concrete and precast iron due to many reasons. Therefore, precast product technologies using polymer concrete are widely developed across the world because using polymer concrete can be over come this limitation. This study reviewed and analyzed the trends of development and practical usages of ploymer concrete precast products in foreign countries based on selected literatures. It was observed that polymer concrete precast products have been widely used as utility structures wall and slab members. decoration products, traffic products, hydraulic structures and industry equipments.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.179-180
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• 2016

This study has a purpose of producing precast concrete for rapid construction of urban railway system. However, previous precast concrete has problem of its weight itself and there has been a keen interest in effect of carbon emission reduction and eco-friendly in our society. Therefore, in order to solve these two problems, we are about to produce precast concrete using lightweight aggregate and eco-lightweight concrete, with which much mineral had been replaced. As a result, we could confirm that it was possible to produce RMC B/P production satisfying the requirement performance of eco-lightweight concrete, which is replaced with a great amount of mineral for reduction of precast concrete's weight and environmental performance. Also, by confirming the possibility of producing precast concrete which lightweight concrete is used, if producing precast concrete by using eco-lightweight concrete, it would be effective to avoid destruction of environment and much useful to use multiple tower crane when constructing. Afterward, we will proceed our study by constructing precast concrete at which eco-lightweight concrete is used for continuous quality improvement.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.661-664
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• 2008

As architectures have recently become high-risers and megastructured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but also internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete for precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1303-1308
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• 2007

Recently, precast concrete tracks are replacing ballast track for efficient and economic maintenance of track. Precast concrete railroad tracks are manufactured in factory, and transported to railroad construction site for installation. Therefore, quality of precast concrete track itself should be sufficiently good. On the contrary to the convenient manufacturing of precast concrete track, the installation of a precast concrete track requires careful steps. Typically, a precast concrete track is placed on an approximately 15-cm thick lean concrete layer. A mortar is filled between lean concrete layer and precast concrete track to adjust the sloping angle of a precast concrete track for a safe train operation at a curvy section. Then, the use of filled mortarproduces a void underneath a precast concrete track, which is harmful to structural safety of a precast concrete track undercyclic loading. Therefore, it is essential to make sure that there is no void left beneath a precast concrete track after mortar filling. In the continuous resonance method, the amplitude of frequency response measured using an instrumented hammer and an accelerometer is plotted against a pseudo-depth, which is half of the wave velocity divided by frequency. The frequency response functions are measured at consecutive measurement locations, 6-cm interval between measurement points, and then combined together to generate a 2-D plot of frequency response. The sections with strong reflections or large amplitude of frequency response are suspicious areas with internal voids and unfilled areas. The 2-D frequency response plot was efficient in locating problematic sections just by examining the color shade of a visualized plot in 2-D format. Some of the problematic sections were drilled to make a visual inspection of mortar filling. The visual image of interface between mortar and precast concrete track was verified using the validity of the continuous resonance technique adopted in this research.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.253-254
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• 2023

The production plan of Precast Concrete members is closely related to the assembly plan of Precast Concrete members, and is an important management factor for the process planning of Precast Concrete construction. This may cause a delay in the construction period due to manufacturing errors occurring in the production process of members and transportation errors according to the production sequence. Therefore, it is necessary to have an efficient production plan for Precast Concrete members that can produce the necessary quantity from the point of assembly of the members and supply them in a timely manner. This study is a basic study for establishing a production plan for Precast Concrete members, and the purpose of the study is to examine the factors that affect the establishment of a production plan for Precast Concrete members. In this study, the influencing factors according to the production method and conditions when establishing a production plan for Precast Concrete members were considered. In the future, correlation analysis among influencing factors will be carried out, and it is expected that it will be used as basic data for schedule management of Precast Concrete construction and derivation of construction period calculation standards.

• Journal of the Earthquake Engineering Society of Korea
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• v.14 no.2
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• pp.15-26
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• 2010

The purpose of this study is to develop a precast concrete structural wall system that can assure reliable seismic performance. In previous studies, the connections of precast concrete structural walls have had some problems in their seismic performance. Therefore, this research proposes precast concrete structural walls which have an improved seismic performance. One is a hybrid precast concrete structural wall that is composed of a reinforced concrete component and a precast concrete component, and another is a precast concrete wall whose reinforcements have a partially reduced section and are partially unbonded from the surrounding concrete. To evaluate the seismic performance of the proposed precast concrete structural walls, the behavior of three specimens, including a reinforced concrete wall, were subjected to reversed cyclic combined flexure and shear. According to the test results, the proposed precast concrete structural walls have reliable seismic performance.

• Journal of Korean Association for Spatial Structures
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• v.20 no.3
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• pp.35-42
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• 2020

The purpose of this study is to develop precast concrete modules that can be used as a booth and a single-story building with a large space. This precast concrete module is originally designed to have a hexagonal facade when the upper and lower parts, which are symmetrical about horizontal connection line, are combined. A structural design was conducted to ensure structural safety of these precast concrete modules and to extend the slope of the inclined members as far as possible. Then the finite element analysis was performed to estimate the lateral and vertical deflection of complete precast concrete modular structures. And to verify the structural safety of these precast concrete modules, weight loading tests were conducted on the upper and lower modules respectively.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.119-122
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• 2009

As architectures have recently become high-risers and mega-structured, stable high strength products have been ensured. Accordingly, use of precast concrete accouplement has been increased in order to facilitate air compression and rationalize construction. Since not only external heating but a1so internal temperature rise caused by the accumulation of cement hydration heat in manufacturing process, precast concrete members with large cross-section used for high-rise mega-structure's columns and beams may exhibit different temperature history compared to the precast concrete members for wall and sub-floor with relatively small cross-sections. Therefore, this study aims to elucidate the characteristics of temperature history of mass concrete members cast with high-strength concrete fur precast concrete application. In this study, large cross-sectional precast concrete mock-up, unit cement quantity, and temperature histories in manufacturing precast concrete member under different curing condition were inclusively investigated.

• Advances in concrete construction
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• v.10 no.1
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• pp.21-34
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• 2020

Precast deck joints have larger crack width than cast-in-place concrete decks. The initial crack typically occurs at the maximum moment but cracks on precast joints are significant and lead to failure of the deck. The present crack equation is applied to cast-in-place decks, and requires correction to calculate the crack width of precast deck joints. This research aims to study the crack width correction equation of precast decks by performing static tests using high strength and normal strength concrete. Based on experimental results, the bending strength of the structural connections of the current precast deck is satisfied. However it is not suitable to calculate and control the crack width of precast loop connections using the current design equation. A crack width calculation equation is proposed for crack control of precast deck loop joints. Also included in this paper are recommendations to improve the crack control of loop connections.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5A
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• pp.463-473
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• 2010

The purpose of this study was to investigate the performance of precast concrete copings for precast segmental PSC bridge columns. The proposed system can reduce work at a construction site and makes construction periods shorter. The precast concrete copings provides an alternative to current cast-in-place systems, particularly for areas where reduced construction time is desired. A model of precast concrete copings was tested under quasistatic monotonic loading. As a result, proposed precast coping system was equal to existing cast-in-place system in terms of required performance. In the companion paper, the experimental and analytical study for the performance assessment of precast concrete copings for precast segmental PSC bridge columns is performed.