Nowadays, a number of buildings is demolished in a year, and most of waste concrete is thrown away to reclaimed land. The committee for disposal and recycling of construction waste which was organized in Building Contractor's Society held a study on the recycling of waste concrete as concrete aggregate. This study had been proceeded from April 1974 to March 1977, and the committee prescribed“The Recommended Practice for Usage of Recycled Aggregate and Recycled Concrete”