Improvement in corrosion resistance of recycled aggregate concrete by nano silica suspension modification on recycled aggregates

This work modified recycled aggregates (RAs) by soaking them in a nano-silica (NS) suspension and evaluated the modification effects on recycled aggregate concrete (RAC). Firstly, different soaking times were studied based on the surface microhardness and the penetration depth of NS particles in the RA. Secondly, mechanical properties (e.g., compressive strength and microhardness of interfacial transition zones) and durability properties (e.g., steel corrosion and corrosion-induced cracking) were tested. The 1-h soaking modification was selected as the optimal soaking time. The nano-modification improved the protection of steel and the resistance to corrosion-induced cracking, which was believed to be related to the improvement of the ITZ properties according to the microhardness test results.