Utilisation of construction and demolition materials with clay for road pavement subgrade

This paper presents the use of construction and demolition (C&D) materials with clay, and a comparative study on the C&D and natural aggregate (NA) utilisation for road pavement subgrade. California bearing ratio (CBR), unconfined compressive strength (UCS), and swelling tests were conducted to analyse the response of recycled concrete aggregate (RCA), dragged asphalt pieces (DAP), and natural gravel aggregate (NA) mixed with a low plasticity clay at various contents (0%, 10%, 20%, 30%, 40%, 50%, and 100%) by dry weight. The laboratory tests indicated that the use of clay in all the aggregates resulted in sharp increase in the UCS values. The CBR analysis showed an 80%, 75%, and 50% decrease in the performance of NA, RCA, and DAP with 50% clay, respectively. Further, the testing results also revealed a slight increase in the swelling percentage of the mixtures by clay additions. Consequently, this research has implications in the design of road pavement subgrades for the field performance of gravel-size-waste and/or NAs and clay mixtures.