Calcium Leaching Mechanism of Cementitious Materials in the Marine Environment

Abstract

Calcium leaching from cement hydrates has been shown to decrease the durability and shorten the service life of the concrete. Earlier studies have focused on investigating the leaching progress in deionized water or ammonium nitrate solutions, neglecting the effects of aggressive ion concentrations, types, and temperatures. In addition, the current equilibrium curve of calcium leaching is based on experimental data in deionized water, and its applicability to calcium leaching in actual marine environments is controversial. In this study, a dissolution experiment was carried out to study the effects of chloride ion concentrations and environmental temperatures. The functional relationship of critical parameters (x1, x2, and Csatu) of the equilibrium curves with the chloride ion concentrations and temperatures was established. Furthermore, considering the influence of calcium leaching on porosity and the diffusion coefficient of cementitious materials, the calcium leaching model was established within a time and space framework. The results showed that calcium leaching was accelerated by the increased concentration of chloride ions and the decrease in environmental temperature. In the authors’ view, this study lays a theoretical foundation for a transport-reaction-mechanical deterioration model of concrete.