Properties of Polymer-Modified Mortars with Nitrite-Type Hydrocalumite

Abstract

Nitrite-type hydrocalumite (calumite) is a corrosion-inhibiting admixture which can adsorb the chloride ions (Cl^-) causing the corrosion of reinforcing bars and liberate the nitrite ions (NO^-₂) inhibiting the corrosion in reinforced concrete. Polymer-modified mortars with the calumite and a styrene-butadiene rubber (SBR) latex as a polymeric admixture are prepared with various polymer-binder ratios and calumite contents, and tested for flexural and compressive strengths, adhesion, water absorption, drying shrinkage, accelerated carbonation, and corrosion inhibition. As a result, regardless of the polymer-binder ratio, the replacement of the ordinary portland cement with the calumite causes a marked improvement in the corrosion-inhibiting property of the polymer-modified mortars but decreases in their strengths and adhesion, and increases in their water absorption, drying shrinkage and carbonation depth. However, such inferior properties are considerably improved with an increase in the polymer-binder ratio irrespective of the calumite content. It is concluded that the polymer-modified mortars with the calumite can successfully be used as patch materials for the repair work for deteriorated reinforced concrete structures.