Hygro-thermal and durability properties of a lightweight mortar made with foamed plastic waste aggregates

In the present study, hygro-thermal and durability related properties of a cementitious mortar containing highly porous foamed aggregates obtained from polymeric end-of-waste materials were investigated. The evaluation of capillary water absorption, thermal conductivity, water vapour permeability and sulfate attack resistance of samples where natural quartz sand was replaced by 10%, 25% and 50% in volume with foamed aggregates was carried out. Experimental investigations showed that the presence of plastic aggregates decreased mortar density (up to 36%, compared to the reference sample, for the maximum investigated natural sand volume replacement) as well as thermal conductivity (10% for the 50% volume replacement). Moreover, water vapour transmission rate increased at increasing natural sand replacement while capillary water absorption decreased. Finally, after fifteen cycles of sulfate attack test, lightweight mortars evidenced a lower mass loss compared to the reference sample. The results were related to morphological modifications in the mortars bulk porosity, demonstrating by mercury intrusion porosimetry investigations, that polymeric foamed aggregates determine a variation of the pores microstructure, resulting in an increased pores dimension.