Influence of metal impurity on recycled aggregate concrete and inspection method for aluminum impurity

Recycling construction demolition waste such as concrete rubbles has become more important for preventing resource depletion and reducing environmental burden. However, recycled aggregate from demolished concrete waste can bring about several problems due to the various impurities included in concrete waste, when recycled aggregates are used for recycled aggregate concrete. Therefore, it is significantly important not only to investigate the influence of impurities on properties of recycled aggregate concrete but also to examine the safety of recycled aggregate. jective of this study is to investigate the properties of concrete containing two types of metal impurities, of which limit content is not specified in standards. To achieve this purpose, experimental works were conducted for concrete containing metal impurities with various size and content and it was found that aluminum, contained in recycled aggregate, caused performance degradation in both mechanical property and durability of recycled aggregate concrete even with very low content less than 0.1%. This paper also suggested a convenient inspection method for aluminum impurity utilized at plants to confirm the safety use of recycled aggregate and to reduce the risk of using recycled aggregate.