Study of road bases construction in Saudi Arabia using foam asphalt

This paper summarizes the research carried out to compare the performance of foamed asphalt pavement mixes with conventional crushed aggregate for the construction of road bases. The research work focused on the investigation and evaluation of the feasible use of foamed asphalt technology for Saudi roads using marginal quality construction materials, marl, and reclaimed asphalt pavement (RAP) materials for local applications. Materials included the Ministry of Transport (MOT) granular base class A and B, subbase material class B, and reclaimed asphalt pavement (RAP) material. Foamed asphalt mixes were designed for subbase class B (foamed SB) and RAP (foamed RAP) material utilizing low percentage of Portland cement. Foamed asphalt mixes were optimized to meet dry and wet indirect tensile strength (ITS) requirements. Designed mixes in addition to granular base class A and B were evaluated for CBR, dynamic resilient modulus at 25 °C and wheel tracking test dry at 50 °C and soaked at 22 °C. Results indicate that base class A has the lowest rutting followed by base class B then foamed SB and finally foamed RAP for dry condition at 50 °C, while foamed RAP has the lowest rutting followed by foamed SB then base class B and finally class A for soaked condition at 22 °C. Portland cement was effective in reducing ITS loss of foamed asphalt mixes. Resilient modulus testing indicated that SB mix has behavior comparable to base class A. Foamed RAP mix has shown the best behavior. Saturation has reduced resilient modulus of all mixes significantly. Foamed asphalt technology can be used successfully to construct road bases from locally available marginal or recycled materials.