Impact of magnesia and titania nanoparticles on characteristics of alkali-activated slag mortars exposed to sulfuric acid solution and elevated temperatures

Abstract

Nanotechnology is being employed as potential solution to alleviate limitations of alkali-activated slag mortars (AASMs). The current study investigated the impact of prepared magnesia (NMg) and titania nanoparticles (NT) at various dosages (0, 1, 3 and 5 wt%) on mechanical and durability characteristics of AASMs. Specimens were either fully immersed in an aqueous solution of sulfuric acid (1 wt% concentration) or subjected to elevated temperatures (250, 500 and 750℃). Microstructural development and densification were analyzed by XRD, FTIR, and SEM with EDX technique to determine the primary improvement mechanism imparted as a result of employing nanoparticles to AASMs systems. Optimum performance prior to and after exposures was achieved for specimens containing 3% NMg and 1% NT in terms of compressive strength, water absorption for unexposed specimens, and weight loss and compressive strength retention for specimens exposed to sulfuric acid solution and elevated temperature. Nanoparticles produced more densified mixtures imparted by their ability to accelerate geopolymerization processes, filling effect and formation of voluminous compounds that further block available spaces in the microstructure.