• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.23-29
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• 2019

This study applies to the surface modification technique by coating the surface of aggregates using the modified paste such as cementitious materials in order to develop completely recycling technology of coarse aggregate. In this case, coating thickness of modified aggregate can be considered that the decision is dependent on the viscosity and tenacity of modified paste. In this study identify the flow properties of the fresh modified paste, and examined for the coating thickness of modified aggregate. As a result, it was possible to design a quantitative coating thickness of modified paste assuming that a modified paste to a Bingham Fluid and consider by excess paste theory and rheology constant (yield value). Accordingly, it is considered that the quantitative mix design of concrete using by surface modified aggregates will be possible.

• Economic and Environmental Geology
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• v.53 no.6
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• pp.755-769
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• 2020

In 2019, about 134 million ㎥ of aggregate was produced in an estimated 880 quarries and pits in 17 metropolitan governments. Leading producing metropolitan cities were Gyeonggi-do, Gyeongsangnam-do, Chungcheongbuk-do, Gangwon-do, Gyeongsangbuk- do, Chungcheongnam-do, in order decreasing volume, which together accounted for about 71% of total product. Of the total domestic aggregates produced in 2019, about 31 % was sand and about 69% was gravel. It estimated that of the 134 million ㎥ of aggregates in Korea in 2019, about 50.3% was produced by screening crushed aggregate by 41.4% by forest aggregate, 3.3% by land aggregate, 1.7% by sea aggregate and 1.7% by washing each other, and 0.7% by river aggregate. This indicates that screening crushed aggregate and forest aggregate are the main producers of domestic aggregates. The most crushed and forest aggregate was extracted at the Gyeonggi-do and Gyeongsangnam-do, respectively. Land aggregate was mainly extracted at Gyeongsangbuk-do and Gangwon-do. Therefore, in the future supply and demand of aggregate resources, it is judged that there should be a primary policy direction for screening crushed and forest aggregate.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.365-370
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• 1996

본 논문은 GIS를 이용하여 원자력 발전소 건설을 위한 최적의 부지 선택 방안을 연구한 것이다. 근래 고도 경제 성장에 따라 전력 사용량이 날로 증가되고 있으며 이에 따라 발전소의 추가 건설이 시급한 실정이다. 그러나 발전소 건설에 필요한 적지가 희소한 실정이며 정부의 국토이용 계획, 각종 개발 제한 사항에 의해 갈수록 제약을 받게 되어 부지 선정에 많은 어려움이 예상된다. 본 논문에서는 기존의 원자력 발전소 입지선정 절차를 근간으로하여 부지평가에 영향을 주리라 예상되는 지질, 골재원, 수송조건, 부지표고, 용수원, 해상조건, 접안조건 및 주변환경, 인구 분포 등의 부지평가 요소들을 중심으로 하고, GIS를 이용한 부지평가 항목의 분석을 통하여 원자력 발전소 부지의 최적 후보지를 결정하는 개념적 방안을 제시하였다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.113-119
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• 2006

It is now established that more than two types of blended aggregate have beneficial effects on quality and supply of concrete in the long run. However, studies on blended aggregate have not widely been progressive and the evaluation method of its most favorable mixture proportion is still needed. Therefore this study investigated the most favorable mixture proportion through the physical experiment of fresh and hardened state's cement mortar, in response to three types of composite ratio, natural fine aggregate(Ns), crushed fine aggregate(Cs) and recycled fine aggregate(Rs). Test showed that increase of blending ratio of Ns and Cs improved fluidity of mot1ar. For the properties of compressive and flexural strength, mortar blending Ns and Cs properly, exhibited similar value to one using only Cs, while mortar mixing Rs showed lower strength value as less as 6% of control one. Mortar using only Rs exhibited the largest drying shrinkage value. In addition, even thought it is not a clear quantitative analysis, technical-imaging-skill presenting the most favorable mixture proportion 3-dimensionally is proposed in this research, in order to notify the proportion easily.

• 한국도로학회:학술대회논문집
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• 2003.10a
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• pp.225-228
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• 2003

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.189-196
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• 2018

Degraded shear performance of reinforced concrete members with recycled coarse aggregate (RCA) compared to flexural strength is a problem. To address this, steel fibers can be used as concrete reinforcement material. In this study, the strength and deformation characteristics of SFRC beams using RCA were to be determined by shear tests. Major experimental variables include the volume fraction of steel fiber (0, 0.5%, 1%), the replacement rate of RCA (0%, 100%), and the shear span ratio (a/d = 1, 2). As a result of the experiment, the shear strength of the specimen increased as the rate of mixing steel fiber increased. For specimens with RCA and 1% steel fiber, the maximum shear strengths increased by 1.77 - 6.25% compared to specimens with normal coarse aggregate (NCA). On the other hand, at 0-0.5% steel fiber, the shear strengths of RCA specimens were reduced by 24.2% to 49.2% compared to NCA specimens. This indicates that reinforcement with 1% volume fraction of steel fiber greatly contributes to preventing shear strength reduction due to the use of RCA.

• Journal of the Korea Concrete Institute
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• v.28 no.4
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• pp.445-454
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• 2016

With the increase of decrepit facilities, construction waste increased to a certain level and now the increase is more or less stabilized. Yet construction waste still constitutes the largest portion of the overall wastes. Also, it is inevitable to spend a huge amount of the national budget due to the aggravating shortage of aggregate caused by prohibition on collection of natural aggregates as well as due to the damage to the land and environment caused by development of the sources of aggregates. As a countermeasure to the situation, the Ministry of Land, Infrastructure and Transport promulgated the quality standard for recycled aggregate to manage the usage of recycled aggregate according to its quality. But use of recycled aggregate for the purpose of high added value still remains nominal. Therefore, this research aims to study the applicability of recycled aggregate concrete as structural concrete by evaluating the quality improvement effects and the performance of the recycled aggregate concrete including recycled fine aggregate and recycled coarse aggregate that have undergone carbonation for 4 days and 14 days respectively in the condition of 60% RH, 20% $CO_2$ and $20^{\circ}C$ temperature, suggested for carbonation modifying from the advance research. The result shows carbonation modify contributed to quality improvement with 0.91% decrease in absorption rate for recycled fine aggregate and 0.7% decrease in absorption rate for recycled coarse aggregate. The physical properties and durability of the recycled aggregate made of aggregate modified by carbonation showed results similar to general concrete, which confirmed the possibility of applying the recycled aggregate made of recycled aggregate modified by carbonation to structural concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.67-73
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• 2017

The concrete pavement slabs that suffer expansion due to the Alkali-Aggregate Reaction(AAR) increase and the increase consequently causes unexpected displacement of bridge abutment. As the expansion due to the AAR is greater than that due to the temperature change, lethal load can act on bridge abutment. Therefore appropriate preventive measures may be necessary. The degree of expansion by AAR depends on the severity of AAR and geometry condition of concrete pavement and road structure. In order to prevent damage to bridge, it is effective to release the expansion force of the concrete. It would be advantageous to replace the concrete pavement with asphalt for a long section of concrete pavement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.120-121
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• 2015

In this research, to evaluate the influence of using non-KS aggregate on concrete performance, the engineering properties of normal strength concrete were assessed depending on the KS aggregate and non-KS aggregate from various sources in mid-Korea. From the experiment, when the non-KS aggregate was used, low compressive strength was achieved with increased water-to-cement ratio caused by increased unit water due to high absorption rate of the non-KS aggregate.

• Economic and Environmental Geology
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• v.54 no.5
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• pp.549-560
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• 2021

In 2019, at 147 local governments, a total of 872 operations produced aggregates with 414 operations by permission, 458 operations by declaration except the marine operations. The leading aggregate sources were, in descending order of the number of operations, crushed, forest, land, washing, river aggregate. By aggregate type, gravel-only operations were slightly more than sand-only ones. By province, Gyeongsangbuk-do had 149 operations, followed by Gyeonggi-do with 135, Gangwon-do with 113, and Gyeongsangnam-do with 92, Chungcheongbuk-do with 81, and Jeollabuk-do with 70. A review of production by size of operation indicated that about 23,100 thousand m³ (17.6% of the total aggregate) was produced by 17 operations reporting production of more than 1 million m³, about 29,900 thousand m³ was produced by 44 operations reporting production between 500 and <1,000 thousand m³, about 60,000 thousand m³ was produced by 273 operations reporting production between 100 and <200 thousand m³, about 17,000 thousand m³ was produced by 409 operations reporting production between 10 and <100 thousand m³. 129 operations that producted less than 10 thousand m³ accounted for 0.4% of total aggregate produced in Korea in 2019. Operations that produce more than 1 million m³ of aggregate was only from forest and crushed aggregate. The period of permission for aggregate producing based on permission is mostly less than 10 years, and in particular, for river and land aggregates, the permission period is very short, less than 2 years.