The Investigation about the Application of the Recycled Aggregate to the Base Course Material
Hiromichi MATSUSHITA, Hiroaki TSURUTA, Atsushi KUBONO, Satoshi FUJIMOTO and Seiichi TANIMOTO
Abstract:At present, rapidly decreasing of natural resources and capacities of final disposal sites become serious problems. In the field of construction, it has been said that demolished concrete should be more reused. Most of demolished concrete have been used as base course materials, especially as subbase course materials. However, in view of environmental protection, demolished concrete must be reused as not only subbase course materials but also upper base course materials and aggregates for concrete. The purpose of this study is to investigate whether demolished concrete can apply for upper base course materials that must satisfy stricter standard than subbase course material. Recycled base course materials used in this study were made of massive concrete, which were obtained from demolishing of bridges constructed in 1959. In order to change grading and particle size, crushing method of recycled base course material was changed in several ways. Moreover, to some of them, adjustment of grading with decomposed granite was taken. Particle size analysis, compaction test and California Bearing Ratio (CBR) test were carried out. As the result of tests, modified CBR value of recycled base course material applied initial crushing could not satisfy the requirement for upper base course materials. However, adjustment of grading with decomposed granite and secondary crushing enabled to use it as upper base course materials. Key Words:Demolished concrete, Crushing, Base course material, Adjusting of grading, California Bearing Ratio (CBR)