Single and combined effects of nano-SiO2, nano-Al2O3 and nano-TiO2 on the mechanical, rheological and durability properties of self-compacting mortar containing fly ash

• Effects of nanoparticles on properties of self-compacting mortar were investigated.
• Fresh and hardened properties of mortar were affected by the nanoparticle dosage.
• Nanoparticles improve compressive strength and durability performance of mortar.
• Adding nano-SiO2 and nano-TiO2 at 5% improved the all-round performance.

This article reports an investigation into the single and the combined effects of nano-SiO2 (NS), nano-Al2O3 (NA) and nano-TiO2 (NT) on the mechanical and durability properties of self-compacting mortar (SCM) containing fly ash. Three different nanoparticles at quantities of 1%, 3%, and 5% of the binder by weight were considered, with a constant fly ash amount of 25% of the weight of cement for all mixtures. Water absorption, electrical resistivity and rapid chloride permeability tests (RCPTs) were performed to observe the durability properties of SCM samples containing fly ash. Compressive strength was obtained at 3, 7, 28 and 90 days. Mini V-funnel flow time and mini slump flow diameter tests were also performed to obtain rheological properties. The results indicate that 1%, 3%, and 5% of the binder provide the best compressive strength for nanoparticles NA, NS, and NT, respectively, when used on their own. For all combinations, the strength increased and reached its peak by the 90th day. The similar improvement effect was also seen with water absorption. In fact, the binary combinations NS/NT (NST) and NS/NA (NSA) at 5% and 1% had the greatest water absorption among all samples. In terms of electrical resistivity and chloride permeability, the best results were obtained with the ternary combination NSAT at 3%. Overall, the best all-round performance was provided by the binary combination NST at 5%.