ABSTRACT
In Belgium, more than 6,000 t of recycled concrete and masonry aggregates are produced every year, coming from civil engineering demolition works. They contain up to 50% of masonry. It is allowed to recycle them in road bases and subbases if they satisfy the requirements set in the standard specifications. Unfortunately, the recycling of those materials in such applications is limited.
In order to better assess the properties of those materials, BRRC has led a project, in collaboration with CTP and ULg, to investigate the specific behaviour of recycled aggregates (recycled concrete and masonry aggregates and recycled concrete aggregates).
Laboratory and field tests were made on recycled aggregates. Cyclic triaxial tests were performed with a new operating procedure, to study the long-term behaviour of those materials. Only permanent strains were considered. The effects of fines content, water content and freeze-thaw cycles were considered. It was observed that water content and fines content have an adverse effect on the long-term performance of materials.
Outdoor test sections were built in order to investigate the effect of frost on recycled aggregates. A section with limestone was also built, to compare the swelling of natural and recycled aggregates. Larger swellings were observed for the recycled materials. We also observed some hardening of the recycled materials. The properties of the materials (for example grading) did not vary with time.
