Effect of Cement and RAP Content on Full Depth Reclamation (FDR) of Low-Volume Roads: A Response Surfaced-Based Study

Full depth reclamation (FDR) of asphalt pavements is a sustainable and economical rehabilitation technique used worldwide. Typically, in any FDR process, recycled materials from pavement layers are mixed with a chemical additive like cement to increase the strength and stiffness of the layer. Additional material in the form of RAP and aggregates is used if the desired depth or gradation is not achieved. This study tries to assess the compressive strength characteristics of FDR by considering open graded premix carpet (OGPC) as RAP material and understand the effects of RAP and cement through statistical methods. FDR specimens were fabricated in the laboratory considering a typical low-volume road composition used in India. The response surface method was employed for the experimental design and development of a response model for FDR compressive strength. Laboratory investigation included unconfined compressive strength (UCS) determination at various test conditions as per the design of the experiment. Results showed that the compressive strength of FDR was within limits specified for a treated granular layer using nominal cement contents for the in situ gradation considered for a full depth reclamation. ANOVA analysis showed that the effects of cement and RAP were significant, whereas the interaction between cement and RAP was not significant within the range of testing. However, the effect of cement was more prominent as compared to the effect of RAP. Further, the response model developed showed good capability for predicting the UCS values within the range used to develop the model.