PURPOSE: To effectively use so called returning-ready-mixed concrete by reusing admixture mixing coral with a surplus material obtained by washing ready- mixed concrete consisting of cement, crushed stone and sand as a base course material for a road.

CONSTITUTION: Cement is washed away from so called returning-ready-mixed concrete such as a surplus material of ready-mixed concrete mixed with sand, crushed stone and cement. While, Ryukyu limestone (upheaval coral reef limestone, so called stone powder or flow-coral, hereinafter referred as to coral) is mined from a coral mine. The coral is added to the surplus material washing a portion of concrete from the ready-mixed concrete, and they are mixed by a mixer to make a base course material 3. In the case the base course material 3 is used for an asphalt pavement, first of all, earth 4 is rolled by a large-scaled roller. After that, the base course material 3 is paved and levelled by a grader, and is compacted. Then, crusher run 2 is paved thereon and is levelled, and roller rolling is made. After that, asphalt is paved thereon and is rolled to complete.