Waste Aggregates in Asphalt Mixtures

As part of the RILEM Technical Committee TC 279-WMR on valorisation of waste and secondary materials for roads, Task Group 3 used various waste aggregates as a replacement for natural aggregates in asphalt mixtures, namely, construction and demolition waste, recycled concrete aggregates and steel slag. For this interlaboratory exchange program, the mixtures were produced by substituting various amounts of virgin aggregates with the aforementioned waste aggregates in various fractions. The results from eight laboratories were compared to a reference mixture in each laboratory with conventional aggregates. The mechanical performance of these mixtures using such alternative aggregates indicates that bituminous mixtures prepared with the investigated waste aggregates required higher amounts of bitumen but had acceptable volumetric properties. Furthermore, they had better mechanical performance, regardless of the source of recycled aggregates. The results show that such aggregates can be a viable option for use in roads, thereby contributing to the zero-waste society and reducing the use of natural aggregates. However, the adaptation of quality control/acceptance criteria and pavement design as well as the development of specific research aimed at assessing the environmental viability and life cycle sustainability of such materials is necessary.