Experimental study of construction and demolition materials with clay

This study presents two different kinds of construction and demolition (C&D) waste materials were used as an aggregate. The C&D materials are dragged asphalt pieces (DAP) and recycled concrete aggregate (RCA), also natural round gravel as a natural aggregate (NA) was used for the comparison. Furthermore, clay was used with these materials in various proportions for preparing the specimens. The clay was added to RCA in contents of 0, 10, 20, 30, 40, 50 and 100% by dry weight. The same contents of clay were used for mixing with the DAP and NA materials. Influence of the clay on these coarse aggregates was analyzed. The tests consist of an intensive series of California Bearing Ratio (CBR) test, swelling test, Unconfined Compressive Strength (UCS) test, and direct shear test. The performed CBR tests revealed that the C&D and NA mixed with low contents of clay (10% and 20%) do not lose a high amount of their CBR values. Testing results indicated slight increase in swelling percentage and there were found to be 0.8, 0.95, and 1.1% for NA, RCA, and DAP mixed with 50% of clay, respectively. The UCS tests showed that there is an escalation in compressive strength, and it reached to 231, 221, and 166 kN/m2 for NA, RCA, and DAP mixed with 50% of clay respectively. In addition, shear resistance will increase by increasing clay content. As it was collected from all tests, the RCA has results in which close to the NA results.