• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.403-404
• /
• 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 Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.337-338
• /
• 2009

Use of the recycled fine aggregate as a material of structural concrete is not easy currently because there are some problems, such as of quality control and the uncertainty of chemical and physical property. Thus, the results indicate that it is possible to produce high quality recycled fine aggregate for structure by microwave heating technology, friction and abrasion action.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.47 no.4
• /
• pp.25-32
• /
• 2005

This study was performed to evaluate the strength properties of polymer concrete using recycled aggre-gate. The compressive strength, splitting tensile strength, flexural strength and pulse velocity of polymer concrete were decreased with increasing the content of recycled aggregate. At the curing age of 7days, the compressive strength was $80.5\~88.3$ MPa, the splitting tensile strength was $9.1\~10.6$ MPa, the flexural strength was $19.2\~21.5$ MPa and the pulse velocity was $3,931\~4,041$ m/s, respectively. Also, the compressive strength, splitting tensile strength, flexural strength and pulse velocity of concrete using recycled fine aggregate were higher than that of the silica sand. Therefore, these recycled aggregate polymer concretes were estimated for high strength concrete without major problem.

• Computers and Concrete
• /
• v.10 no.2
• /
• pp.95-104
• /
• 2012

This study uses recycled green building materials based on a Taiwan-made recycled mineral admixture (including fly ash, slag, glass sand and rubber powder) as replacements for fine aggregates in concrete and tests the properties of the resulting mixtures. Fine aggregate contents of 5% and 10% were replaced by waste LCD glass sand and waste tire rubber powder, respectively. According to ACI concrete-mixture design, the above materials were mixed into lightweight aggregate concrete at a constant water-to-binder ratio (W/B = 0.4). Hardening (mechanical), non-destructive and durability tests were then performed at curing ages of 7, 28, 56 and 91 days and the engineering properties were studied. The results of these experiments showed that, although they vary with the type of recycling green building material added, the slumps of these admixtures meet design requirements. Lightweight aggregate yields better hardened properties than normal-weight concrete, indicating that green building materials can be successfully applied in lightweight aggregate concrete, enabling an increase in the use of green building materials, the improved utilization of waste resources, and environmental protection. In addition to representing an important part of a "sustainable cycle of development", green building materials represent a beneficial reutilization of waste resources.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2003.05a
• /
• pp.73.2-79
• /
• 2003

The purpose of this study is to provide the basic data on the optimum method for interfacial separation for an effective recycle of concrete waste by using the thermal properties of concrete. Therefore, this study is proceeded by dividing the interface of concrete into cement paste and fine aggregates or mortar and coarse aggregate, considering the aspect of recycled cement and aggregate as the recycling use of concrete waste. As results of the experiment, in case of recycle cement, the interfacial separation is easily appeared, but it is shown that the mixed amount of powder included in fine aggregate doesn't greatly decrease. But, in case of recycle coarse aggregate, the effect of interfacial separation by preliminary heating is predominant. Especially, the bonding rate of mortar is the lowest when it is heated 5 times for 120 minutes at $300^{\circ}C$. Hence, it is considered that it will be an excellent effect of quality control when the results of this study is applied to a manufacturing system of recycle coarse aggregate which is about to put into practical use.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.05a
• /
• pp.37-38
• /
• 2013

The fine powder obtained from the manufacturing process of recycled coarse aggregate contains unhydareted cement particles on their surface. It is believed that the alkalinity of the powder (11.0-12.5) is enough to active the slag-based composites. In this paper, the obtained powder was sieved and divided into two sizes, i.e., 0.08 mm and 0.3 mm, and added to the slag-based mortar. Results showed that the fine powder had an effect on the slump and the compressive strength of slag-based composites. With the different pH values of the powder, it could be seen that the distance between the two level powders. And found the peak 28 days compressive strength as the replacement ratio of the recycled aggregate powder changed. The findings from this study provide an indication that with achieved compressive strength, the fine powder can be used in a light weight concrete.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.1
• /
• pp.70-78
• /
• 2023

Blast furnace slag, a by-product of the steel industry, is mostly recycled as concrete admixture, but electric arc furnace slag has not been recycled to date. In particular, since electric arc furnace slag partially contains free lime (free-CaO) in the discharge, it is necessary to review this in order to recycle f or construction materials. Recently an atomizing process which is a method of rapidly cooling electric arc furnace slag has been developed and applied. Therefore, in order to use the fine aggregate of oxidized slag from electric furnace restored by this method as an aggregate for concrete, physical damage and chemical reviewing are required. In this study, a physical and chemical review was conducted on the fine aggregate of Electric Arc Furnace Oxidizing Slag (EFOS) as a by-product of the steel manufacturing process with atomizing process. In this experimental study, EFOS was experimentally examined about whether it can be used as concrete fine aggregate. Also, we intend to provide basic data for the future use of the EFOS fine aggregate. As a result of the experimental study, it was found that the fine aggregate of the EFOS satisfied the quality standards of the fine aggregate for concrete in most items specified by Korean Standard.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.7 no.4
• /
• pp.79-87
• /
• 2012

Recently, Development of substitution aggregate is urgently needed because aggregate shortage is continuing due to the exhaustion of natural aggregate and strict restrictions of environment in construction industry. Therefore, This paper was examined the fundamental properties for application of FINEX slag by finex process as fine aggregate for concrete. Through this study, we propose the practical method of FINEX slag as fine aggregate for concrete.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.11a
• /
• pp.124-125
• /
• 2015

Recycled aggregate is not used for structures because of negative awareness of quality. for improving the negative awareness, a concrete structure was built with 100% recycled aggregate and monitoring mechanical properties and durability was conducted. As a result, It was observed that mechanical properties and carbonation of structures with 100% recycled aggregate were fine.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.1
• /
• pp.23-29
• /
• 2022

This study was conducted to confirm the applicability of recycled aggregates as aggregates for structural concrete as a way to respond to the shortage of natural aggregates. The two-stage mixing approach developed by Tam et al. is known to be a method that can improve the mechanical performance of recycled aggregate concrete without the installation of new additional facilities. In this work, modified version of two stage mixing approach, which was used in our earlier work, was introduced to prepare mortar specimens with recycled fine aggregate, and the compressive strength and fire resistance were compared to mortar mixed with normal mixing approach. According to the experimental results from mortar with recycled fine aggregate, the use of two-stage mixing approach was found to be more effective than normal mixing approach for compressive strength development. In addition, the residual strengths of the mortar with two-stage mixing approach was higher than mortar made of normal mixing approach after exposure to 600 and 900 ℃. It is possible to manufacture high-performance cement composites with recycled fine aggregates through the active use of the two-stage mixing approach.