• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.520-525
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• 2001

Compared with the blast furnace slag, steel slag has the expansibility due to the reaction with water and free CaO. Therefore it is specified in Standard Specification for Concrete in Korea that steel slag aggregate must not be used in concrete. So it is unusual to use steel slag aggregate in concrete. In this study steel slag aggregate processed by several aging process was comparatively satisfied with fundamental properties as concrete aggregate, which are specific gravity, absorption, unit weight, percentage of solids and abrasion value etc. And chemical analysis is observed to understand the effect of aging process in steel slag aggregate. When the strength is measured, it is found that the concrete replacing crushed stone with steel slag aggregate had a little problem without sufficient aging process

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.328-329
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• 2018

The problem of imbalance between supply and demand of fine aggregates in the southeastern region due to the decrease in collection of EEZ(Exclusive Economic Zone) sea sand has been raised. In this paper, the possibility of securing alternative aggregate as a means to solve the problem of fine aggregate shortage in the southeast region was analyzed. As a result of the analysis, the alternative aggregate is easy to manufacture and its quality can be secured. And, it is suitable to use as an aggregate with less environmental burden. In addition, institutional improvement measures are needed for effective utilization and recycling of alternative aggregates.

• Computers and Concrete
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• v.23 no.3
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• pp.155-160
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• 2019

The use of recycled aggregate concrete for the purpose of environmental and resource conservation has gained increasing interest in construction engineering. Nevertheless, few studies have reported on the bonding performance of the bars in recycled aggregate concrete after exposed to high temperatures. In this paper, 72 pull-out specimens and 36 cubic specimens with different recycled coarse aggregate content (i.e., 0%, 50%,100%) were cast to evaluate the bond behavior between recycled aggregate concrete and steel bar after various temperatures ($20^{\circ}C$, $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$). The results show that the recycled aggregate concrete pull-out specimens exhibited similar bond stress-slip curves at both ambient and high temperature. The bond strength declined gradually with the increase of the temperature. On the basis of a regression analysis of the experimental data, a revised bond strength mode and peak slip ratios relationship model were proposed to predict the post-heating bond-slip behavior between recycled aggregate concrete and steel bar.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.151-152
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• 2023

Lightweight aggregates has a dry specific gravity of 2.0 or less, which is lower than natural aggregates. Lightweght aggregate is efficient for weight reduction but has low compressive strength. In this study, EIS(electrochemical Impedance Spectroscopy) was used to confirm the ITZ(Interfacial Transition Zone) between the lightweight aggregate and cement paste according to the coated of blast furnace slag powder. As a result of EIS measurement, the correlation between ITZ characteristics and compressive strength was determined. The phase angle of EIS was different depending on the blast furnace slag powder coated of the lightweight aggregate. The surface-cotead lightweight aggregate was improved and the ITZ was strengthened.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.365-372
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• 2010

This paper was to evaluate the influence of kiln process parameter(kiln angle, kiln rotating speed) of lightweight aggregate using waste glass and bottom ash with industrial by-products on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis. In the results of surface plot and contour plot, it has verified that kiln residence time of lightweight aggregate increase as kiln angle and rotating speed decreases. For this reason, pore size and quantity tend to increase by active reaction of forming agent. It seems to be that increase in pore size and quantity have caused decreasing density, fracture load and thermal conductivity, and increasing water absorption. In conclusion, optimization of kiln process parameter on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis are kiln angle 2.4646%, kiln rotating speed 40.7089 rpm.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.6
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• pp.25-34
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• 2022

Recently, as a study to air cooled slag, which is an industrial by-product, research is being proceed to use it as a material for concrete. In this study, the workability, air content, compressive strength, CO₂ emission and economic feasibility of concrete were analyzed when air cooled slag, an industrial by-product, was applied as aggregate for rural road pavement concrete. As a result of the analysis, both the slump and air contents test results of concrete using the air cooled slag aggregate satisfied the target values, and the compressive strength was increased when the air cooled slag aggregate was used compared to when the natural aggregate was applied. On the other hand, the largest amount of CO₂ emission by raw material was found in aggregate. The carbon emission of rural road pavement concrete using air cooled slag aggregate increased when the Korean LCI DB was applied compared to when natural and crushed aggregates were applied, and the emission decreased when the German LCI DB was applied. This results are due to differences in the viewpoints of industrial by-products. However, considering the recycling of waste from the environmental aspect, it is necessary to simultaneously review the CO₂ emission and recycling aspects in the future. Also, the application of air cooled slag aggregate had the effect of improving the economic efficiency of rural road pavement concrete about 18.75%.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.249-254
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• 2002

In Korea, due to the shortcomings of natural aggregates and increasing needs of crushed stones, it is necessary to examine the alkali-aggregate reaction of the crushed stones. The purpose of this study is to analyze petrographic properties and alkali-aggregate reaction of crushed stones This study was peformed to investigate the alkali-aggregate reaction of crushed stones using chemical analysis, physical properties, XRD, XRF and mortar-bar method.

• Communications for Statistical Applications and Methods
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• v.8 no.2
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• pp.327-336
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• 2001

This work concerns estimating a regression function, which is not linear, using aggregate data. In much of the empirical research, data are aggregated for various reasons before statistical analysis. In a traditional parametric approach, a linear estimation of the non-linear function with aggregate data can result in unstable estimators of the parameters. More serious consequence is the bias in the estimation of the non-linear function. The approach we employ is the kernel regression smoothing. We describe the conditions when the aggregate data can be used to estimate the regression function efficiently. Numerical examples will illustrate our findings.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.133-136
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• 2005

Compressive strength of recycled aggregate concrete was tested by the core and by the non-destructive testing. A prediction model of compressive strength considering the replacement level of recycled aggregate was suggested by multi-regression analysis and was compared with test results. Also, Test results showed that the ratio of compressive strength by core and non-destructive testing to actual was somewhat affected by the replacement level of recycled aggregate.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.69-76
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• 2012

A recent shortage in Korean aggregate market leads a social demand to utilize recycled aggregate to more advanced level, such as the use in concrete structures or paving materials for surface and base layers. Government announced a recycled aggregate guideline in 2009 to provide an institutional framework for recycled aggregate in such an up-scaled use. The use of recycled aggregate in such use; however, is very minimal. This paper evaluates the validity of the impurity content criteria of recycled aggregate for lean concrete base through a series of material tests. The analysis results shows that reclaimed asphalt pavement (RAP) in recycled aggregate not only influence a strength lean concrete adversely, but also influence negatively on an absorption and abrasion characteristics of aggregate system significantly that made those two indices lower. Since absorption and abrasion characteristics are very important indices for recycled aggregate quality, RAP in recycled aggregate could significantly mislead the recycled aggregate qualification. This paper provides a suggestion to resolve these problems.