Engineering properties of construction and demolition material blends for pavement subbase applications

A detailed laboratory study is carried out to evaluate the engineering properties of the Recycled Concrete Aggregate (RCA) coming from the construction and demolition waste to be used in the stabilized subbase of the flexible pavement. The index properties such as impact test, abrasion test, specific gravity, water absorption, and pH test were carried out on the RCA material. The RCA was blended with the natural aggregate (NA) in 20% to 100% with an increment of 20%. The cement was added in the 3%, 4%, 5%, and 6% to the RCA and NA material blend to make a bound subbase layer. On the combination of RCA, NA, and cement proctor tests, the Unconfined compressive strength (UCS) test, durability test, and Repeated load triaxial (RLT) test were carried out. The results support the use of RCA material in the subbase layer of flexible pavement with UCS of more than 1.5 MPa, which is the Indian standard requirement. Even the durability under wet and dry cycles was satisfied by all combinations except combinations having 100% RCA + 3% Cement. From the RLT test, the resilient modulus (Mr) was found for different fifteen stages of confining pressure and deviator stresses. The Mr values increase with the increment in deviator stress and confining pressure. The combinations showed better performance in terms of strength with natural aggregate added in RCA to be used in the bound subbase layer of the flexible pavement.