• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.197-200
• /
• 2004

The increase of the use of recycled aggregate is necessary for the decrease of building waste, but it is not possible to use concrete because of the various range of quality. Therefore, the quality grade and application method of recycled aggregate should be prescribed before the site application so in that this study we investigated the effect of the quality of recycled aggregate on the compressive strength, resistance freezing and thawing. As results of this study, the compressive strength of recycled aggregate concrete used recycled aggregate, as if it had high quality recycled aggregate is similar or higher to that of crushed stone. Also, this high quality recycled aggregate affect the increase of resistance freezing and thawing.

• International Journal of Concrete Structures and Materials
• /
• v.6 no.4
• /
• pp.239-246
• /
• 2012

Pervious concrete is a tailored-property concrete with high water permeability which allow the passage of water to flow through easily through the existing interconnected large pore structure. This paper reports the results of an experimental investigation into the development of pervious concrete with reduced cement content and recycled concrete aggregate for sustainable permeable pavement construction. High fineness ground granulated blast furnace slag was used to replace up to 70 % cement by weight. The properties of the pervious concrete were evaluated by determining the compressive strength at 7 and 28 days, void content and water permeability under falling head. The compressive strength of pervious concrete increased with a reduction in the maximum aggregate size from 20 to 13 mm. The relationship between 28-day compressive strength and porosity for pervious concrete was adversely affected by the use of recycled concrete aggregate instead of natural aggregate. However, the binder materials type, age, aggregate size and test specimen shape had marginal effect on the strength-porosity relationship. The results also showed that the water permeability of pervious concrete is primarily influenced by the porosity and not affected by the use of recycled concrete aggregate in place of natural aggregate. The empirical inter-relationships developed among porosity, compressive strength and water permeability could be used in the mix design of pervious concrete with either natural or recycled concrete aggregates to meet the specification requirements of compressive strength and water permeability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.11
• /
• pp.7-15
• /
• 2017

The purpose of this study was to evaluate the properties of recycled aggregate concrete (RAC) using low quality recycled aggregate with or without washing before usage. The recycled aggregate concrete evaluated in this study contained various amounts of low quality recycled aggregate, viz. 30%, 60% and 100%. To evaluate the performance of the recycled aggregate concrete, various test methods were employed to assess its compressive strength, absorption, surface resistance, ultrasound velocity, chloride ion resistance, etc. The properties of the RAC with 30% and 60% washed recycled aggregate were similar those of the natural aggregate. However, the properties of the RAC with 100% washed recycled aggregate were slightly lower than those of the other versions. Also, the RAC with the non-washed recycled aggregate exhibited lower performance results. The results showed that the RAC with washed recycled aggregate had similar properties to normal concrete (concrete using natural aggregate). This implies that the recycled aggregate should be washed to improve the RCA.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.94-97
• /
• 2003

Recently, owing to the deterioration of reconstruction and the construction, much of the construction waste is discharged in our construction field, and the amount of construction waste are rapidly increased. These waste are raised to financial and environmental problems, so the method of reusing waste concretes has been studied and carried out many direction. Especially being want of resources, if waste concrete could be recycled as aggregate for concrete, it will contribute to solve the exhaustion of natural aggregate, in terms of saving resources and protecting environment. This study is that the floating properties of concrete with recycled coarse aggregate were investigated for the substitution of recycled coarse aggregate. The result of this study, in case of water reducing, the property of harden concrete for the substitution ratio of recycled coarse aggregate was increased. The Quality of recycled coarse aggregate concrete was improved by water reducing.

• Journal of the Korea Concrete Institute
• /
• v.13 no.6
• /
• pp.575-583
• /
• 2001

The purpose of this study is to present the method of utilizing the recycled aggregate that are obtained from waste concrete as the concrete aggregate. We manufactured the recycled aggregate concrete with compressive strength of over 300kgf/㎠ to increase its weaker strength than the normal concrete, and compared the physical features of the recycled aggregate concrete with that of the normal concrete. As a result of the study, the mechanical performances such as compressive and tensile strength were generally reduced as the mixing rate of the recycled aggregate increased; however, it was possible to manufacture the concrete with the compressive strength of 300∼600kgf/㎠ using the adequate mixing material such as unit quantity of cement, compounding water and silicafume. However, a continuous study on long-term durability performance is required to manufacture and utilize the recycled aggregate concrete for the structure.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2002.05a
• /
• pp.637-642
• /
• 2002

In this study, the experiments of recycled aggregate concrete with fly ash and special blended slag powder or diatom calcined at 650$\circ$ were performed on compressive strength, shrinkage and creep. The compressive strength of concrete with recycled aggregate and pozzolanic materials were higher than that of concrete with crushed stone and OPC. On the other hand, the shrinkage and creep of concrete with recycled aggregate and pozzolanic materials was smaller than that of concrete with crushed stone and OPC. Futhermore, the shrinkage and creep of recycled aggregate concrete with fly ash and special blended slag powder was a little decreased that of recycled aggregate concrete with fly ash and diatom. Relationship between compressive strength and creep coefficient was shown to the linear relation like as $\sigma$$_{c}$= -30CF＋404.4.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.81-84
• /
• 2006

This study is intended for how to utilize the recycled fine aggregate which is produced by concrete wastes. It analyzes the quality of the fine aggregate which is reproduced through the acid treatment process, and comprehends the characteristics of mortar using the recycled fine aggregate to review whether it can be put to practical use for concrete. The conclusion of the study are as follows 1. The recycled fine aggregate through the acid treat shows the low rate of absorption and high density. 2. Compared to the mortar made from acid liquid precipitated recycled fine aggregate, using nature water precipitated one reduces the flow. 3. The compressive strength of mortar using recycled fine aggregate tends to be reduced according to the kind of precipitated water. Based on the above results, the recycled fine aggregate through the acid treatment process satisfies the quality standards of the first-grade recycled fine aggregate of KS F 2573 (recycled fine aggregate for concrete) but it is concluded that the recycled fine aggregate through the acid treatment process can not used as fine aggregate used concrete because it has destructive characteristics when the mortar is produced

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.364-367
• /
• 2004

The purpose of this study is to investigate quality of recycled fine aggregate manufactured by drying manufacturing system which is the manufacture method of high quality recycled fine aggregate, and to analyze on the fresh, hardened and durability properties of recycled concrete using it. Therefore it is to present the fundamental data for structural application of recycled concrete. The results of this study are as follows; Quality of recycled fine aggregate by drying manufacturing system is improved, and compressive and tensile strength of recycled concrete using high quality recycled fine aggregate are similar to those of normal concrete. But, durability such as carbonation, salt damage and dry shrinkage show decreased somewhat.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.367-375
• /
• 2022

In this study, the characteristics of recycled aggregate concrete according to the mixing ratio of recycled fine aggregate were analyzed by design strength to explore its use in the production of ready-mixed concrete. The results show that, depending on the ratio of recycled aggregate, the compressive strength is similar to that of normal concrete and does not deteriorate. Therefore, it is possible to achieve a strength similar to the target design strength. Furthermore, if the ratio of recycled fine aggregate for concrete is up to 25 % of the total aggregate amount (50 % of the to-tal fine aggregate), slump does not cause problems. Our findings show that the higher the de-sign standard strength, the greater the amount of powder, and management of slump reduction, unit quantity, and performance system is necessary. The obtained results show that recycled ag-gregate can be used for the production of ready-mixed concrete after adjusting its mixing ratio and concrete mix proportions.

• Journal of the Korea Concrete Institute
• /
• v.15 no.2
• /
• pp.197-208
• /
• 2003

This paper is to determine the possibility of re-using waste concrete from Incheon city area. The strength test was conducted with five aggregate compounds which was replaced a natural aggregate with recycled aggregate. After checking the physical characteristics of recycled aggregate compounds, the mix design of recycled concrete was conducted. For the relatively comparison between natural and recycled compounds, while the unit aggregate weight was changed, other conditions were fixed. The freezing and thawing test which included fly-ash and super-plastezer were performed to check the durability and workability when recycling waste concrete. In the physical characteristics of recycled aggregate, it was found that the specific gravity of recycled coarse aggregate and recycled fine aggregate satisfied the first grade of recycle specification(KS), and all compounds of recycled aggregate also satisfied the second grade of absorption specification, Especially up to the 50% substitution of recycled aggregate is equal to or a bit lower than that of convention aggregate. In comparison with conventional concrete, the recycled concrete is lower than maximum by 7% in compressive strength decreasing rate after freezing-thawing test. From now, although most of recycled concrete was used to the building lot, subgrade, asphalt admixture, through the result. It was proved that possibility of re-using recycled aggregate as the substructure of bridge, retaining wall, tunnel lining and concrete structure which is not attacked the drying shrinkage severely.