Evaluation of the mechanical properties and durability of cement mortars containing nanosilica and rice husk ash under chloride ion penetration

•Use of nanosilica hydrosols with different surface areas and rice husk ash in mortar.•Compressive strength, chloride migration, electrical resistivity and capillary absorption.•Nanosilicas with lower surface areas had better performance at higher ages.•Rice husk ash mixes displayed the lowest strength and durability.•The best performance at the ages of 28 and 90 days was of binary mixes.

In this study, the influence of nanosilica hydrosols and rice husk ash (RHA) on the compressive strength, chloride permeability, electrical resistivity and capillary absorption of single and binary blended mortars was investigated. Results showed that the incorporation of nanosilica improved mortar performance, while RHA did not have a significant influence and mainly attributed to lower strength and durability at early ages. It was found that the addition of RHA in mixes containing nanosilica, dramatically decreased compressive strength at ages of 3 and 7 days. However, binary mixtures displayed the best results for strength development and durability at ages of 28 and 90 days.