• Resources Recycling
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• v.24 no.5
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• pp.63-71
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• 2015

The purpose of this study is to investigate the optimum replacement rate and material properties of eco-friendly recycled concrete using recycled coarse aggregates and rapid-chilled steel slag fine aggregates. The replacement rate of recycled coarse aggregates was increased from 30% to 50% of total volume of coarse aggregates and the rapid-chilled steel slag aggregates were substituted for 10% to 50% of total volume of fine aggregates. As a result, the increment of recycled coarse aggregates in concrete caused the reduction of the compressive strength. On the other hand, as increasing the replacement ratio of rapid chilled steel slag aggregates, the compressive strength was enhanced. Furthermore, the optimum use of rapid chilled steel slag aggregates was suggested up to 20~30% of fine aggregates and the use of it could be helpful to expand the replacement rate of recycled aggregates.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.43-49
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• 2015

The objective of this paper is to investigate experimentally the effect of the substitution of recycled aggregates under 13mm on the properties of the concrete using coarse aggregate with size of 13~25mm. Recycled aggregate under 13mm were substituted to the concrete ranged from 10% to 100%. To compare the properties with the case of recycled aggregate, crushed stone with smaller than 13mm was also substituted to the concrete by 20% and 40%. Test results showed that increase of recycled aggregate under 13mm resulted in the increase of slump and compressive strength compared with plain mixture, which was made with only aggregate with 13~25mm size. This is due to the dense gradation of aggregate in association with addition of relatively small particle. It is thought that the use of recycled aggregate under 13mm along with 30% contributes to the quality improvement of the concrete made with only 13~25mm aggregate.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.95-102
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• 2011

Vicker's hardness and pore size distribution of mortar adhered to the recycled coarse aggregate were tested according to the strength level of original concrete of recycled coarse aggregate to find the change of mortar adhered to the recycled coarse aggregate in cement paste. The strength levels of original concrete of recycled coarse aggregate were 25.5MPa, 41.7MPa and 60.1MPa and the aggregates were used at the state of saturated surface dry condition and oven dry condition. The results of this experimentation indicated that the mean value of Vicker's hardness was increased according to age and strength of original concrete of recycled aggregate. Porosity of $100nm{\sim}10{\mu}m$ size was reduced and porosity of 6nm~100nm size was increased in cement paste.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.199-206
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• 2018

Due to the advantages of less raw materials and fossil fuel consumption, lower carbon footprint, and the capability of pavement performance improvement, the recycling technology of asphalt is developed and applied for road rehabilitation and construction in the western countries over the past two decades. Cold recycled asphalt mixtures are bituminous materials normally made by mixing recycled aggregate from wasted asphalt with an asphalt emulsion and water at room temperature. This paper aims at investigating the properties of cold recycled asphalt mixture with alkali-activated filler according to wasted asphalt aggregate content. As a result, as the content of wasted asphalt aggregate increased, the marshall stability of cold recycled asphalt mixture decreased and void ratio increased. Also, grading curves for cold recycled asphalt mixture as specified in GR criteria were satisfied in all aggregate mixing conditions regardless of the wasted asphalt aggregate content.

• Resources Recycling
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• v.18 no.3
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• pp.20-26
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• 2009

The objective of this study is to investigate the properties of fresh concrete with recycled coarse and fine aggregates. Four different kinds of aggregate with natural, recycled aggregates were prepared. The concrete mixtures were produced with test parameters of replacement ratio of recycled aggregate. The properties of the fresh concrete were measured by means of slump and air content according to elapsed time. Quality control method to maintain the constant total mixing water for recycled aggregate concrete was suggested. The all concrete mixtures were produced with approximately the same slump on the job site after an hour. Test results indicated that compressive strength of concrete with constant slump is not affected by the replacement ratio of recycled aggregate. Also the practical way for the quality control of recycled aggregate concrete is to maintain the constant total mixing water.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.246-252
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• 2021

The basic properties and volume stability of the ultra-rapid setting cement mortar containing low-quality recycled aggregate with a higher water absorption and lower specific gravity than relavent Korea Standard were experimentally confirmed. The mix proportion without recycled aggregate followed that of the general repair mortar used in the fields. 15% and 30% of the fine aggregate was substituted by the recycled aggregate in the mixtures with and without latex emulsion, and properties and characteristics of the mortar including mortar flow, setting time, compressive and flexural strength, and linear deformation under sealed and unsealed conditions were evaluated. It was confirmed that when low-quality recycled aggregate was used by 30%, there were risks of decrease in the early-age strength by up to 50% within 24h and increases in drying shrinkage by up to 2 times for 2 weeks compared to the the mixtures without the recycled aggregate.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.625-630
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• 2002

The availability of natural aggregates has decreased in recent years due to depleting reserves. From the viewpoint of energy and resources saving, it may be advantageous to use the waste concrete as construction aggregates. The purpose of this study is to analyze petrographic and chemical properties of recycled aggregate, and to investigate the resistance of concrete to rapid freezing and thawing by using replacement ratios (0, 10, 20, 30, 40, 50, 60, 70, 100% ) of recycled aggregate.

• Magazine of RCR
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• v.8 no.4
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• pp.16-20
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• 2013

• Magazine of RCR
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• v.7 no.2
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• pp.11-14
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• 2012

• Magazine of RCR
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• v.7 no.2
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• pp.15-18
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• 2012