Resistance of blended cement pastes to leaching in distilled water at ambient and higher temperatures

Abstract

This paper outlines an investigation on the resistance of ordinary Portland cement (OPC) pastes with and without mineral admixtures to leaching in distilled water at ambient and elevated temperatures of approximately 30 and 80 C, respectively. The effects of water-binder ratio (w/b), mineral admixtures, microstructure, and water-curing period were also explored. An immersion test using thin plate specimens was conducted to accelerate and study the leaching behavior of these materials in distilled water. Mercury intrusion porosimetry was performed to examine the change in microstructure, while thermogravimetric analysis was carried out to determine the free calcium hydroxide and calcium carbonate contents within the cement matrix. Based on visual observation together with change in mass, pore structure, porosity, free calcium hydroxide, and calcium carbonate contents, the resistance of cement pastes to leaching was evaluated, and guidelines on the design of concrete structures subjected to leaching in distilled water at both ambient and higher temperatures are provided.