• Journal of the Korean GEO-environmental Society
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• v.6 no.3
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• pp.17-23
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• 2005

In Korea, the production of reclaimed concrete materials has been increased due to the increase in the concrete structures taken down every year. The reclaimed concrete materials have been reused as road materials. However, the studies on their mechanical and environmental properties have been very limited. The recycled rate of the materials is currently low in Korea. This paper presents the investigation of mechanical and environmental properties of the reclaimed concrete materials, as well as the comparisons with those of gravel. For the evaluation of the mechanical and environmental characteristics, following tests were conducted on both reclamed materials and gravel; liquid limit, plasticity index, CBR, sand equivalent test, abrasion test, pH test, and column leaching test. The test results showed that the reclaimed concretes satisfy the requirements for use as roadbase, subbase, and subgrade materials, except base materials. The pH of reclaimed concrete materials was less than 11 and the leaching test results satisfied the regulatory requirement of Waste Management Act in Korea. Based on the investigations, it appears that the reclaimed concrete materials are environmentally safe and applicable for use as road materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.137-140
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• 2006

This study make an investigation into the quality of sand supplied with remicon manufacturing plant and examine concrete influenced by a source of supply of sand. As a result of the indoor test, the quality of crushed sand, EEZ sand and sand of north korea are worse than general sea sand. therefore, crushed sand, EEZ sand and sand of north sand lower quality of concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.403-404
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• 2009

This study has investigated application of the industrial by-product of reject ash and recycled fine aggregate to consider the economical issue to high flowing CLSM(controled low-strength material). But this high flowing CLSM is required more binder, so it has been estimated the influence of reject ash content, use of recycled fine aggregate and crushed sand, and air content about properties of CLSM.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.235-236
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• 2011

This study analyzed flowing and strength properties of mortar depending to fine aggregate types and replacement ratio by using blast furnace slag, red mud, and silica fume that are industrial by products. The findings showed that higher replacement level of fine aggregate increased air content while decreased table flow. In addition, compressive strength showed that the higher replacement level was regardless of fine aggregate types, the lower strength became. Mortar substituted by the dredged sand showed high strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• v.y2004m10
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• pp.55-58
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• 2004

This paper investigated the results of quality of concrete using mixed sand with grading adjustment in order to find out the applicability of fine aggregate with bad grading, According to test results, fluidity of concrete with fine level grading river sand was decreased while with coarse level grading crushed sand increased compared with that with medium level grading crushed sand. Use of mixed sand with grading adjustment(MSG) resulted in an improvement in fluidity. Increase in fineness modulus led to an increase in bleeding, For compressive strength, use of MSG increased compressive strength. For drying shrinkage, use of fine level grading river sand resulted in an increasing drying shrinkage due to the larger presence of fine particles, while use of MSG led to a reduction in drying shrinkage

• The Journal of the Petrological Society of Korea
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• v.24 no.3
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• pp.253-272
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• 2015

The necessity of aggregate resources in Korea has been increased with a rapid economic growth since the 1990s. Construction activities have been increased drastically for last two decades. Such economic activities are much concentrated at big cities in Korea, and recently new neighbouring cities, such as multifunctional administrative city, enterprise city and innocity, are under construction at the surroundings of the cities. This new urbanization asked for an appropriate supply of raw construction materials such as cement, sands and gravels. The aim of this study is to understand and discuss the analysis and prospect of supply and demand of domestic sand and gravel. On the early years, 1990s, about 25% of the total consumption of these sands and gravels comes from riverine deposits; 20% to 25% from marine sands, 40% to 45% from forest rocks and the rest 5% to 15% from old fluvial deposits and crushed rocks. But nowaday the river aggregate, including both sands and gravels of a present river channel and those of the old fluviatile system are decreasing, while the crushed and forest aggregates and marine sand are now the main source of infrastructure resources. Thus it is increasingly necessary to investigate the forest and crushed aggregate resources potential in Korea where a current analysis indicate that the supply of riverine aggregates gradually decreases.

• The Journal of Engineering Geology
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• v.1 no.1
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• pp.2-10
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• 1991

Some geotechnical considerations might be suggested to the construction performance from the school and the housing projects in Tripoli sub-region, Libya. The subsurface informations were compiled from the site investigation reports, for which more than 700 borings and lots of laboratory test had been conducted from 1984 to 1986. Most subsurface of 10 meter depth in the Jafara plain consists of medium dense silty sand. Some ground in the plain have poor top soil with interbedded calcarenite or limestone. The shallow subsurface is found to be very poor soil in the southern mountain range. Weak soil is hardly found except in the sabkha area. In general, natural silty sand layer may have a presumed bearing capacity of more than 150kN/$m^2$, where spread or strip footing is applied. Proper fine aggregate and natural coarse one are restricted in Tripoli sub-region. Coarse aggregate is generally supplied from the dolomite quarry.

• 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.

• Industry Promotion Research
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• v.6 no.4
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• pp.1-9
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• 2021

The purpose of this study is to manufacture lightweight aggregates for recycling water treatment sludge, to identify the physical properties of the aggregates, and present a method of utilizing the manufactured lightweight aggregates. The chemical composition and thermal properties were examined via a raw materials analysis. The aggregate examined here was fired by the rapid sintering method and the single-particle density and water absorption rate were measured. Water treatment sludge has high ignition loss and high fire resistance. When 30wt% of purified sludge was added, the single-particle density of the aggregates was in the range of 0.8~1.2g/cm³ at a temperature of 1,150~1,200℃. At temperatures of 1200℃ or higher, ultra-light aggregates having a single-particle density of 0.8 or less could be produced. When applied to concrete by replacing the general aggregate in the concrete, a specimen having strength values of 200 to 450 kgf/cm² on 28 days was obtained, and when applied as a filter material, the performance was equal to or higher than that of ordinary sand.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.75-84
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• 2008

Recycled-aggregate porous concrete pile (RAPP) which forms a composite ground is one of new ground improvement techniques. In this paper, triaxial compression tests are carried out to investigate the shear strength characteristics of RAPP-Clay composite samples. The main purpose of the tests was to investigate the effects of area replacement ratio ($15%{\sim}100%$) on behaviors of RAPP-Clay samples during shearing. Also, triaxial compression tests using Sand-Clay composite samples were performed to compare with the behaviors of RAPP-Clay samples. The test results showed that the friction angle and cohesion of the RAPP-Clay composite were $18{\sim}34$ degree and $557.0{\sim}588.0\;kPa$, respectively, whereas those of sand-clay composite samples were 26~35 degree of friction angel and $4.0{\sim}18.0\;kPa$.