• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.65-71
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• 2007

Since pop-outs are occurred recently on concrete surface occasionally, it is needed to find out accurate causes and to suggest appropriate methods. On this study, it is investigated the occurrence mechanism of pop-outs caused by electric arc furnace Oxidizing slags as fine aggregate for concrete. As a result, it is investigated the cause of pop-outs that extremely small quantities of free CaO and free MgO in the electric furnace slag react with water to produce $Ca(OH)_2$ and $Mg(OH)_2$, so that their volumes are expanded and erupted about two times. As a resolution, it is needed to remove the potential cause of expansion by replacing the deteriorated concrete section up to the depth to secure the safe of structural element with repairing polymer mortar, especially more than 50MPa.

• Korean Journal of Plant Resources
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• v.25 no.4
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• pp.407-415
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• 2012

Pinus pumila, which occurs in the northeast Asia, is found limitedly in Daecheongbong area of Mt. Seorak in the South Korea. This population was chosen to study spatial pattern, genetic diversity and spatial genetic structure. There were 48 polymorphic and 30 monomorphic I-SSR markers. A total of 65 individuals which distributed in the study site (40 m ${\times}$ 70 m) showed weakly aggregate distribution (Aggregate Index = 0.871). A total of 40 genets were observed from 65 individuals through I-SSR genotype comparison. Proportion of distinguishable genotype (G/N), genotype diversity (D) and genotype evenness (E) were 61.5%, 0.977 and 0.909, respectively. In spite of the small number and the limited distribution, Shannon's diversity index (I = 0.567) was relatively high as compared with those of other plant species. Spatial autocorrelation using Tanimoto's distance showed that the genetic patch was established within 12 m. Based on Mantel tests, there was relatively low correlation between genetic distance and geographic distance. Therefore, it seems the P. pumila population was formed by many parent trees in early stage. For ex situ genetic conservation of P. pumila, the sampling strategy is efficient at least above 12 m between individual trees.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.129-141
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• 2024

This study derived production-production multipliers using a regional input-output table and estimated the induced effect of aggregates through the non-metallic minerals sector and the concrete products sector. In deriving the induced effect of aggregates, it is difficult to use the regional input-output table due to the sector classification problem. This study analyzed the non-metallic mineral sector, including aggregates, as aggregates sector, and the concrete products sector, which uses most of the aggregate production. By analyzing this, we attempted to alleviate difficulties caused by sector classification restrictions. In the process of estimating the induced effect, it was assumed that there was a decrease in aggregate production, and in the process of analyzing the concrete products sector, the effect of the decrease in concrete product production due to the decrease in aggregate production, that is, the decrease in production of one unit of aggregate was 0.8511 in the concrete product sector. The analysis was conducted on the premise of a decrease in unit production. Inducing effects within and between regions were calculated for the 17 metropolitan cities and provinces classified by the regional input-output table. The employment effect was also calculated, assuming a 10% production decrease to show differences according to the size of the aggregate and concrete product sectors in each region.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.211-216
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• 2002

Recently, the more the PET bottles are needed, the more waste PET bottles were produced. So, if there was no suitable recycling, that was contaminate our environment and use up the natural resources. This paper deals with the artificial lightweight aggregate(ALA), made of waste PET bottles, and the properties of concrete replaced with ALA. As a result of experiment, it is shown that the specific gravity of PBLA is 1.39, the unit volume weight is 844 kg/$cm^3$, and absorbing rate is 0. In absorbing rate test, the rate is 10 % increased by replacing of 20 % PBLA and the mixture rate for water and cement is 44.6 % and 51.2 %, in case target strength for 240kgf/$cm^2$, and 270kg/$cm^2$, by added PBLA 75 % and 50 % respectively. So, to obtain a certain target strength, appropriate W/C ratio is required the replacement ratio of PBLA.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.04a
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• pp.34-39
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• 1993

Recently inappropriate aggregates are used as a raw material for ready-mixed concretes, due to the shortage of natural aggregate resources and the prohibition of their extraction for the environmental protection. We, therefore, have conducted experiments to obtain some knowledge of properties of domestic aggregates and to investigate subsequent changes in the properties of the fresh and hardened concretes. To this end, aggregates currently used in 13 domestic ready-mixed concrete plants were collected. Most of aggregate used in this experiment satisfied the KS in density and unit weight. But some of the aggregates have the particle size distribution that can effect bad influence on concrete. In this experiment the aggregates are found to have a bad particle size distribution, resulting in high amount of a unit water content and a unit cement content in concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.245-248
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• 1999

In our standard specification, the specific provision of steel fiber pavement concrete didn't describe yet. The purpose of this study presents criteria of recycled aggregate steel fiber pavement concrete including standard crushed stone steel fiber pavement concrete. This study examined a lot of factors which influence consistency of SFRC(Steel Fibre Reinforced Concrete) including crush stone and recycled aggregate. According to this examination, this study decided optimum S/α and W which are essential to pavement concrete mix proportion. Come to the conclusion, this study is expected to effect economically in recycling of resources and bring to affirmative result in aspect of environment.

• 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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• 2016.10a
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• pp.30-31
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• 2016

Recently in the construction site is required various performance of mortar to deal with reliability, economy. Especially of environment-friendly, saving resources and high performance of mortar it began to require improvement of performance. Therefore, in this study, a series of tests was designed to develop a using mud flat mortar in view of the high absorption rate of tidal flats, to fix the water cement ratio to 70%. The mixing ratio were 10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6 of fine aggregate and mud flats. Compared the flow value, chloride content, compressive strength, tensile strength, and workability of fine aggregate the substituted mud flat mortar and basic cement mortar, present the basic data on the characteristics and effects of mud flat mortar.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.50-51
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• 2021

Recently, as concrete is used in many construction works in Korea, the use of aggregates is also increasing. However, the depletion of aggregate resources is making it difficult to supply and demand high-quality aggregates, and the use of defective aggregates is causing problems such as poor performance such as the liquidity and strength of concrete pouring out in the field. As a result, quality tests such as sieve analysis test is conducted on their own, but this study was conducted to improve time and manpower by using the CNN-based Deep Learning Model for the fineness modulus.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.101-108
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• 2015

The quantities of heavy weight waste glass have been progressively increased because of the rapid industrialization and the change of quality of life. And, the most of them are not recycled. The heavy weight waste glass have been treated by illegal dumping or being buried in landfills. Meanwhile, in order to ensure the safety of nuclear power plant structure, the excellent construction materials are socially required for shielding performance. Concrete is the most widely used construction material, the huge amounts of natural resources are required to make concrete. So, it is needed to investigate the possibility of recycling of heavy weight waste glass as concrete material ingredient. In this study, the heavy weight waste glass was evaluated for the applicability as fine aggregate of shielding concrete. From the results, when heavy weight waste glass was replaced as fine aggregate of mortar, shielding performance can be improved due to increasing in unit weight of mortar. It showed that the strength decreased according to mixing of heavy weight waste glass, Non-Washed heavy weight waste glass is more advantageous in the strength development than Washed case.