Evaluation of the Physical Properties of Unbound Base Layer Containing Recycled Aggregates

Construction industry is among the major contributor to the production of solid wastes, which have become a main problem of societies in present days.Asphalt and cement concrete are among the main engineering materials which are wasted in vast quantities every year due to the reconstruction and demolition of highways and buildings.Recycling of these materials would be an efficient measure for protection of environment and preservation of natural resources.In this research, the viability of using crushed waste asphalt and cement concrete as a replacement of primary aggregate in unbound base layer of flexible pavements has been investigated.Different portions of the natural aggregate have been replaced with the recycled materials and the physical properties of each mixture have been investigated.The physical properties including sand equivalent, toughness, water absorption, density, soundness and compaction have been evaluated for the mixtures.The results show that, they have potential to be used in unbound base layer.Inclusion of any amount of recycled cement concrete in unbound aggregate results in a mixture which satisfy the minimum required sand equivalent, toughness and soundness for unbound base.