Compaction and CBR properties of RAP/sand blends in Iraq

Abstract

Nowadays, Iraq is experiencing a rapid reconstruction process during which a significant amount of construction waste material is generated. One of such materials is RAP (reclaimed asphalt pavement) which is obtained from the removal of surface pavement of roads and used especially as an aggregate substitute in asphalt mix, granular base and sub-base material for roads, or as road fill material. From this point of view, the primary objective of this study was to evaluate the possible effects of adding sand to RAP in terms of compaction and strength properties and to suggest a possible recycling application. For this purpose, RAP and sand samples were collected from Iraq. Then, RAP/sand blends were prepared by mixing RAP with 5%, 10%, 15%, 20%, 25%, and 50% sand by weight. Modified Proctor Compaction and California Bearing Ratio (CBR) tests were performed on these samples. The results have revealed that the compaction properties of the RAP/sand blends were significantly improved as compared to RAP samples resulting in increased maximum dry density and optimum moisture content. CBR values of the tested mixtures had also increased with increasing sand content similar to the results of previous studies. The primary finding of this study was that RAP/sand blends with a sand content of 20% or more were defined to be suitable for use as road fill material according to the American Association of State Highway and Transportation Officials (AASHTO) standards in terms of tested parameters, providing a new field for recycling of RAP in the studied region.