Evaluation of the optimum value of lightweight expanded clay aggregate incorporation into the roller-compacted concrete pavement through experimental measurement of mechanical and thermal properties

The mechanical and thermal properties of roller compacted concrete pavement (RCCP) are considerably influenced by its aggregate. This study determined the optimum value of lightweight expanded clay aggregate (LECA) incorporation into the RCCP through the response surface methodology (RSM) with mechanical and thermal properties evaluation. LECA was replaced as coarse aggregate in different percentages of 25, 50, 75, and 100% (by volume) to develop lightweight and high-insulation capacity RCCP, which could be appropriate for cold climatic zones. Two different mixtures of RCCP with normal-weight aggregate comprising 12% and 15% cement were used as control mixtures. The results showed that incorporating LECA at any percentage in RCCP produced more workable concrete. The substitution of LECA in 25-100% decreased the density of RCCPs containing 12% and 15% cement about 8-24% and 7-23%, respectively, while the water absorption increased around 4-77% and 8-72%. The thermal conductivity of RCCPs decreased by increasing the LECA replacement as coarse aggregate. Also, the LECA replacement increment in RCCPs resulted in lower heat capacity values. Overall, it can be concluded that incorporating LECA in RCCP by around 37% as coarse aggregate would satisfy the standards in terms of fresh, mechanical, and thermal properties.