Durability Performance of Cementitious Mixes with Reclaimed Asphalt Pavement Aggregates

The effect of fine fraction of Reclaimed Asphalt Pavement (RAP) aggregates on durability characteristics of mortar and concrete were assessed. The natural fine aggregates were replaced by finer fraction of RAP at 25%, 50%, 75% and 100% by volume. Resistance to sulfate and acid attack, drying shrinkage, alkalinity, chloride content and presence of carbonation of the mixes were analyzed. Increase or equivalent strength was observed for both mortar and concrete specimens with 50% or lower RAP replacement level under sulfate attack in sodium sulfate solution in comparison to decrease in strength under sulfate attack in sulfuric acid and acid attack in hydrochloric acid solutions. This is due to difference in formation and filling of pores and microcracks by salt-crystallization products in mortar and concrete. The pore distribution characteristics such as threshold diameter supports this observation as well. The threshold diameter decreases from control mix to 50% RAP mix and then increases. Similar pattern of observation was seen in concrete mixes as well. The drying shrinkage of RAP inclusive cementitious mixes were within the stipulated limits. The RAP inclusive concrete mixes do not pose any threat to the reinforcement due to absence of carbonation, chloride content being lower than the maximum limits and pH content between 12 and 13. From the study, it may be concluded that fine RAP inclusive cementitious mixes have durability life and has the potential to be used as pavement quality concrete.