• Journal of the Korea Institute of Building Construction
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• v.16 no.4
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• pp.297-303
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• 2016

Shrinkage Reducing Agent(SRA) was developed in order to control drying shrinkage cracks in concrete, and the use of SRA is increasing since it can control drying shrinkage cracks and improve the quality of concrete structures. Although there are many types of prediction equations of drying shrinkage strain, there is no prediction method which can consider the effect of SRA up to the present. Therefore, it is impossible to predict the tensile stress generated by drying shrinkage of SRA concrete, and to investigate the quantitative serviceability limit state of SRA concrete. In this study, the drying shrinkage of SRA concrete was investigated by experiment and analysis in order to suggest the predictability of drying shrinkage of SRA concrete. As a result, AIJ model, ACI model, GL2000 model showed there was a correlation between the predicted values and the experimental values within the error range of ${\pm}10%$. However, CEB-FIP model and B3 model underestimated the experimental values.

• Journal of the Korea Institute of Building Construction
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• v.14 no.3
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• pp.230-236
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• 2014

This study was carried out to investigate the manufacturability of artificial lightweight aggregate as a way to recycle basalt powder sludge, which is a waste produced during the manufacturing process of basalt in Jeju. Powdered waste glasses and calcium carbonate are used to improve the characteristics of manufactured artificial lightweight aggregate. Especially, considering the complex factors of basalt powder sludge, powdered waste glasses, and sintering method, the amount of calcium carbonate is appropriate at the 9 wt.% in order to improve the intumescent of lightweight aggregate. Also, the amount of powdered waste glasses is effective with using less than 50 wt.% and applying the direct sintering method at the same time on decreasing the absorption of lightweight aggregate. Furthermore, in order to manufacture artificial lightweight aggregate of high quality with a low specific gravity and low water absorption, it is considered to be more effective to apply the direct sintering method after the surface of artificial lightweight aggregate is covered with powdered waste glasses.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.63-72
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• 2017

This research investigated the effect of solar radiation on the temperature distribution in concrete mat foundation. Zhang and Huang Model was utilized to estimate solar radiation heat at a given date and time. A one-dimensional finite element formula was derived with the fundamental laws of heat transfer and Galerkin method. Based on the formula, a one dimensional finite element analysis code was developed using MATLAB. Hydration heat analysis of mat foundation were conducted using the developed code. It was found that the solar radiation reduced the maximum temperature difference in mat foundation, and this temperature difference reduction was more prominent in case of summer season cast, a higher initial concrete temperature, and a thicker mat foundation depth. The research recommended that the solar radiation should be considered in hydration heat analysis of concrete mat foundation so as not to overestimate the maximum temperature difference in mat foundation.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.23-30
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• 2017

The aim of the research is to suggest an economical and sustainable method of reducing pH of recycled aggregate as an embanking and a covering materials. Because of the unhydrated cement based materials on the surface of the recycled aggregate, it causes a severe problem on environment with leaked high alkali water from embankment and covering by using recycled aggregate. In this research, to reduce the pH of recycled aggregate, regarding the recycled fine aggregate, eight different methods were tested and analyzed with three different categorized: natural treatment, artificial treatment, and chemical treatment. From the results of experiment, it was considered that the most efficient method of reducing pH of recycled aggregate was the chemical treatment using acid such as $CO_2$ acceleration or monoammonium phosphate (MAP), and diammonium phosphate (DAP). Especially, using MAP and DAP, fertilizers, is the most efficient method of reducing pH with its time duration and performance.

• Journal of the Korea Institute of Building Construction
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• v.4 no.1
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• pp.119-126
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• 2004

Generally, reinforced concrete is one of the most commonly used structural materials and it prevents corrosion of steel bar by high pH of interior, But, as time elapsed, reinforced concrete structure become deteriorated by many of combined deterioration factors and environmental conditions. And, there are large number of deteriorate mechanism of the reinforced concrete structure and it acts complexly. It is recognized that steel bar corrosion is the main distress behind the present concern regarding concrete durability. In this study, to institute combined deterioration environments, established acceleration condition and cycle for combined deterioration environments has a resemblance to environments which are real structures placed. After that to confirm corrosion properties of reinforced concrete due to permeability with covering depth and types of surface cover under combined deterioration environments, measured carbonation velocity coefficients, chloride ion diffusion coefficients, water absorption coefficients, air permeability coefficients and electric potential, corrosion area ratio, weight reduction, corrosion velocity of steel bar. The results showed that an increase in age also decrease carbonation velocity coefficients, increase Chloride ion diffusion coefficients and increases water absorption coefficients. As well, an increase in age also increases corrosion of steel bar. Data on the development of corrosion velocity of steel bar with types of surface cover made with none, organic B, organic A, inorganic B, and inorganic A is shown. As well, permeability and corrosion velocity of steel bar with covering depth is superior to 10mm than 20mm. And it is confirmed permeability and corrosion properties of steel bar are closely related.

• Journal of the Society of Disaster Information
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• v.8 no.2
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• pp.148-157
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• 2012

Recently, evacuation safety of building residents becomes the major concern, as the building has been higher and more complicated. Many high-rise multi use buildings are under construction in Korea. Required evacuation time using stairway is longer in high-rise buildings, moreover it is impossible for the disabled to evacuate by using stairway. For this reason the study on the effectiveness of using elevator for evacuation is being progressed. Elevator shaft flow coefficient is the major factor for the calculation of elevator piston effect. The results of this study can be used for the study of elevator piston effect as basic data. The flow coefficient simulation was performed using FLUENT, commercial CFD program. As a result of the flow coefficient simulation, the coefficient is 0.88 considering the safety factor. This result is verified that the result of experimental study, 0.86 is conservative.

• Fire Science and Engineering
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• v.32 no.3
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• pp.14-18
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• 2018

The earlier studies on the fire resistance performance of woods used as building materials have focused on confirming combustion characteristics of fire retardant or flame resistant treated wood. In this paper, to confirm internal temperature changes closely related to pyrolysis of woods exposed to the flame, heating experiments were conducted in a heating furnace according to the standard heating temperature curves after Douglas-fir, which is widely used as structural materials, was treated with a flame resistant solution and flame retardant paint. As a result of the experiment, it was confirmed that the thermal diffusion inside the wood has decreased when the wood was treated with the flame resistant solution. However, in high temperature, the flame resistant effect could not be expected due to the peeling of the coating in the case of the flame resistant paint treated wood. Therefore, it can be considered that it is more effective to use the flame resistant solution which penetrates in to the inside of the wood than flame resistant paint which forms the coating on the surface of the wood in order to enhance the flame resistance effect on the thick wood.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.609-616
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• 2021

In this experimental, water-repellent powder, which is a metal salt-based inorganic substance, and natural zeolite powder, which is a pozzolan-based material, were mixed into cement mortar, and their physical properties and resistance to moisture were confirmed. It was confirmed that the test specimen using natural zeolite at the same time had excellent resistance in the water permeation test and the chloride penetration test as compared with the test specimen in which the inorganic metal salt-based water-repellent powder was mixed alone. When a metal salt-based water-repellent powder is used, it cannot be uniformly dispersed inside water due to its insoluble property, and is limited to the surface. When used at the same time as natural zeolite, the setting time at the initial stage of hydration is fast due to the pozzolan reaction, and the water-repellent powder adheres to the porous of the natural zeolite and is evenly distributed inside the test specimen to generate some water resistance.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.39-46
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• 2019

A three-dimensional flow simulation model for high flow concrete was developed using Incompressible Smoothed Particle Hydrodynamics (ISPH), which can solved Navier-Stokes equation with the assumption of a fluid to be incompressible. For the simulation, a computer program code for ISPH was implemented with MATALB programming code. A piecewise cubic spline function was used for the kernel function of ISPH. Projetion method was used to calculate the velocity and pressure of particles as a function of time. Fixed ghost particle was used for wall boundary condition. Free surface boundaries were determined by using virtual density of particles. In order to validate the model and the code, the simulation results of slump flow test, $T_{500}$ test and L-box test were compared with experimental ones. The simulation results were well matched with the experimental results. The simulation described successfully the characteristics of the flow phenomenon according to the change of the viscosity and yield stress of high flow concrete.

• Journal of the Korea Institute of Building Construction
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• v.19 no.2
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• pp.105-112
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• 2019

Fine aggregate made of ferronickel slag(FNS) is similar to natural fine aggregates and is used in concrete structures both domestically and abroad, but its applications and research areas are limited. In this research, in order to expand the availability of FNS and improve the performance of cement mortar products, the applicability of FNS on dry mortar for floor was examined. Experimental results show that FNS improves flow of cement mortar because it has low absorption rate, spherical shape, and glassy surface. Also, the high stiffness of the FNS aggregate itself is considered to contribute to the improvement of cement mortar quality such as crack reduction by improving the compressive strength and shrinkage reducing. In addition, when FNS fine aggregate is applied, it was possible to secure the impact sound insulation performance equal to or higher than that of mortar using natural fine aggregate.