High Performance Granular Base and Subbase Materials Incorporating Reclaimed Asphalt Concrete Pavement

Abstract

This study focused on the material characterization of granular materials containing different percentages of “RAP”. A series of laboratory tests results were carried out to determine the physical and mechanical properties of natural aggregates and various aggregate-RAP blends. The results were used to evaluate methods to develop high-performance granular layer for pavement construction through proper compaction and control of RAP usage. The resilient modulus and accumulative deformation characteristics were determined in relation to RAP content, relative density, compaction method, stress level, stress state and the number of load applications. The effects of RAP content and density on the CBR values of aggregate-RAP blends under various conditions were also investigated. In addition, the effect of small strain cyclic loading on shear strength of aggregate-RAP blends was observed in laboratory tests. Results from this investigation demonstrated that: 1) adding RAP to natural aggregates may increase the resilient modulus of natural aggregates, and optimum content can be found to achieve the highest resilient modulus; 2) resilient modulus generally increases with density; higher density of aggregate-RAP blends can be achieved by using methods combining vibration and static loading. 3) deviatoric stress has more pronounced influence on accumulative deformation than confining pressure. 4) proper compaction method can reduce accumulative deformation of samples. 5) addition of RAP into aggregates results in little change in accumulative deformation when the RAP content is less than a threshold. 6) CBR value decreases with increasing RAP content and decreasing compaction effort or compacted dry density. 7) shear strength of an aggregate-RAP blend tends to increase after small strain cyclic loading.