Bond Strength between Steel and Recycled Asphalt Pavement Aggregate and Recycled Concrete Aggregate

The bond strength behavior between steel and concrete made with recycled concrete aggregates (RCA) and/or recycled asphalt pavement aggregates (RAP) was experimentally investigated by testing 90 concrete cubes of cross section 150 mm x 150 mm using pull-out tests. In this paper, two steel bars (10 mm, 12 mm) and fifteen aggregate combinations were adopted. In each combination, five aggregate replacement ratios were considered: 20%, 40%, 60%, 80% and 100%. The test results indicated a decrease in the tensile load capacity as the content of recycled asphalt pavement (RAP) increased. The combination of RCA and RAP showed a reduction in bond stress for specimens with 10-mm steel bar about 6% to 15% compared to natural-aggregate (NA) samples, whereas for specimens included 12-mm steel bar, the reduction in bond stress was about 6% to 45% compared to NA samples. Furthermore, the design bond strength values calculated according to ACI were lower than the experimental bond strength values. Hence, ACI equations could be reasonably used to predict the proposed strength. Similarly, EC equations could be employed for bond strength except for 100% RAP specimens.