Rutting performance of cement-treated base and hot mix asphalt layer in flexible pavements containing recycled concrete aggregates

Cement Treated Base (CTB), when used in base course, has shown better performance against rutting than conventional base materials. This study focuses on the use of recycled coarse aggregates (RCA) as partial replacement of natural coarse aggregates (NCA) in CTB and hot mix asphalt (HMA) layers of flexible pavements. 30% NCA were replaced with RCA to study the rutting performance of flexible pavements by using 100 mm thick rutting samples prepared with 50 mm thick layers of CTB and HMA each. Four types of specimens with 100% NCA, 30% RCA and 70% NCA in CTB only, 30% RCA and 70% NCA in HMA only, and 30% RCA and 70% NCA in both CTB and HMA were used. Specimens were tested at 40 degrees C, 50 degrees C, and 60 degrees C at a constant number of 10,000 passes (5,000 load cycles). It was concluded that the CTB has a significant impact on the overall rutting performance of the samples due to its rigidity. Use of 30% RCA as a replacement of NCA was found to be acceptable, except for pavements with RCA in both layers. A statistical model was also developed and predicted responses from the proposed relationship were in close agreement with the experimental results.