• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.609-612
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• 2008

This study investigated effect of recycled fine aggregate quality on strength properties of concrete. Some investigations have been carried out to study the strength properties of recycled aggregate concrete. But these have some limitation due to small-scale test in the laboratory. Therefore concrete using this study were fabricated by ready-mix concrete. Variables were quality of recycled fine aggregate(high and low quality) and replacement ratio of 0%, 30%, 60%, 100%(high quality), 35, 70%(low quality). The change of air content of recycled aggregate concrete were similar to natural aggregate concrete. Replacement ratio of recycled aggregate was not necessarily correlated with compressive strength and modulus of rupture of recycled aggregate concrete.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.431-439
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• 2009

These days the amount of demolished concrete waste has been increasing due to reconstruction and redevelopment of aged buildings. So the use of recycled aggregates is recommended to solve environmental problems. Some investigations have been carried out to study the flexural behavior of reinforced concrete beams with recycled aggregates. But these have some limitation due to the use of low quality recycled aggregates and small-scale specimens in the laboratory. The purpose of this experimental study is to evaluate the flexural behavior of simply supported RC beams subjected to four-point monotonic loading and made with recycled aggregates. Seven full-scale RC beams were manufactured with different replacement level of recycled aggregates. The main parameters of the study are combination of aggregates. From the test results, the flexural behavior of the beam is described in terms of crack patterns and failure modes. And the flexural strength of RC beam with different types of recycled coarse aggregates and recycled fine aggregates is compared with the provision of KCI code.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.39-42
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• 2005

This study investigates influence of organic fiber reinforced materials, affecting crack reduction of cement mortar using low grade natural sand(LNS). According to the test, for the properties of fresh mortar, the mortar using natural sand(NS) exhibited that flow value increased until adding most of fiber less than 1$\%$, except for Polyvinly alchol fiber(PVA), and then it decreased. Meanwhile, the mortar mixed with LNS showed that increase of fiber content decrease flow value, regardless of fiber type. Air content increased in the mortar adding nylon fiber(NY) and polypropylene fiber(PP), while it maintained or decreased in the mortar adding cellulose fiber(CL) and PVA. Compressive strength of the mortar does not affect during early age, but mortar using NS and adding 0.1$\%$ of fiber content increased the value, except for PP, at 28 age days, while the mortar mixed with LNS decreased. For the properties of tensile strength, mortar, using NS and adding individually PP and PVA, exhibited higher value. Especially 0.1$\%$ of NY provided the highest value. In addition, the mortar mixed with LNS resulted in improved tensile value as fiber content increased. It is demonstrated that mortar using LNS led to higher length change ratio than natural sand.