Effect of aqueous sodium silicate on properties of recycled aggregate mortar

Abstract

This study investigates the influence of sodium silicate (Na2SiO3) (NS) on the strength and durability performance of recycled concrete aggregate bearing mortar (RAM). NS is used as 0%, 1%, 2%, 3%, 4%, and 5% by weight of cement in RAM. Natural aggregate mortar (NAM) serving as control mix is also produced using natural sand. Compressive strength, sorptivity coefficient, apparent porosity, chloride penetration, and mass loss due to H2SO4 are investigated at various ages. Experimental results indicate that RAM shows inferior strength and durability properties compared to NAM. RAM with 2–3% NS shows 4–9% higher compressive strength than NAM. 2–3% NS also improves the durability of RAM by significantly reducing water sorptivity and permeable porosity compared to corresponding blank mix. RAM shows significant mass loss due to H2SO4 attack compared to NAM, whereas, RAM with 2–4% NS shows acid attack resistance comparable to that of the NAM. Based on experimental results, it can be established that RAM with 2–3% NS can outperform NAM by noticeable margin in strength–durability–economic performance.