Abstract
In recent years, the amount of concrete waste is increasing every year by demolishing and renewing of concrete structures in Japan. In addition, it is expected to continue to increase in the future. In addition, there is a concern about the decrease of disposal sites, so it is necessary to have an effective method to use concrete waste. As an effective method of using concrete waste, the use of recycled aggregate can be considered. In order to promote the use of recycled aggregate, it is necessary to promote the use of low-quality recycled aggregate that can be produced with low energy and low cost. However, the strength and durability of concrete using low-quality recycled aggregate are significantly lower than those using normal aggregate. In previous studies, we examined the improving methods of mortar using low-quality recycled fine aggregate and concrete using low-quality recycled coarse aggregate. It was found that accelerated carbonation of recycled aggregate was optimal for mortar using low-quality recycled fine aggregate, and addition of C–S–H type accelerator was optimal for concrete using low-quality recycled coarse aggregate. Therefore, in this study, we aimed to improve the strength and durability of concrete using both low-quality recycled fine and coarse aggregate, so we examined the improving methods and its mechanism. There are two methods to improve the strength and durability of concrete using low-quality recycled aggregate: accelerated carbonation of recycled aggregate and addition of C–S–H type accelerator. As a result, it was found that the combinations of accelerated carbonation of recycled fine aggregate and addition of C–S–H type accelerator had a high improving effect in concrete using both low-quality recycled fine and coarse aggregate.
Published Version
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