ABSTRACT
Abstract Demolished concrete accounts for the largest part of construction waste. If all demolished concrete is disposed of, final disposal areas, which are even now running short, will soon be filled up. On the other hand, aggregate resources for concrete are nearly being exhausted. The development of new sources for aggregate is becoming also difficult. Reproducing aggregate from demolished concrete and recycling for concrete are paramount technologies for resolving the problems of shortage of waste disposal areas and exhausted aggregate resources, while preventing environmental pollution. However, conventional recycled aggregate has been of low quality for structural concrete and has not been accepted by owners of such structures as building and bridges requiring high performance. Problems also exist in the concrete production and supply systems, whereby normal aggregate and low-quality recycled aggregate cannot be easily changed according to uses. To solve these problems, it is necessary to improve the quality of recycled aggregate, i.e., to minimize the cement portions adhering to recycled aggregate to attain the quality approximating to original aggregate. It is more advantageous in the long run to use completely recyclable concrete, which can incorporate byproducts of other industries. Such technologies have been being developed recently, realizing the production of high quality recycled aggregate. Keywords: concrete, construction byproducts, demolished concrete, recycled aggregate, recycle, waste.
