Compaction Characteristics and Bearing Capacity of Recycled Materials for Road Construction

Abstract

Due to the scarcity of virgin materials, the reuse of granular materials in the road construction becomes of growing importance. However, the use of such recycled materials should not lead to a decrease in quality of the bearing capacity and the life cycle of the road. The compaction of recycled materials requires existing techniques to be adapted to achieve this requirement. The classic compaction theory of granular soils, when applied to recycled materials, does not satisfy the demands on the quality because of the different grain strengths. The recycling materials require increased compaction energy. The Swiss standard on compaction of soils is actually based on the classical AASHTO standard method, which has been the worldwide leading protocol in this field of research. Several tests measuring the bearing capacity and the compaction characteristics of two typical recycling materials have been carried out at the ETH (Swiss Federal Institute of Technology). An attempt has been made in order to correlate the degree of compaction and the bearing capacity of the recycled materials. The bearing characteristics have been measured following the standardized CBR test; the compaction test has been performed according to the Swiss standards. These tests two an interesting response from the recycled materials, which do not match the known dependence of compaction, density and bearing capacity.