Assessment of mortar with fine recycled aggregates and nanoparticles of titanium dioxide under accelerated carbonation

The controlled utilization of recycled concrete aggregates (RCA) has emerged as a sustainable practice to mitigate the depletion of natural resources. However, their use remains limited to reduced percentages, particularly for fine recycled concrete aggregates (FRA), due to their inferior properties such as increased water absorption and porosity resulting from the old adhered mortar. This study explores a novel approach involving the use of titanium dioxide engineered nanoparticles (TiO₂-ENPs) to coat 100% FRA in percentages of 0.5%, 1% and 2% by weight of aggregates, followed by an accelerated carbonation process using carbon dioxide (CO₂). The mortars only coated with TiO₂-ENPs exhibited reduced porosity compared to those only subjected to CO₂ carbonation. The compressive and flexural strength results showed an increase, reaching values close to those of the mortar made with natural aggregates (NA). Remarkably, the combined use of TiO₂-ENPs and CO₂ yielded synergistic improvements in both physical and mechanical properties, achieving results superior to those of the NA series. This study showed the promising potential of utilizing TiO₂-ENPs and CO₂ carbonation to effectively reuse 100% FRA in mortars, providing a viable path towards sustainable construction practices and resource conservation.