Effects of carbonation curing regimes on alkalinity of self-compacting concretes for marine artificial reef

Abstract

This study aims to explore the application practicability of self-compacting concretes with ordinary Portland cement as cementitious material and utilization of CO2 carbonation curing for marine artificial concrete reef. Carbonation curing regimes decreased the surface grinding leachate pH value of designed self-compacting concretes obviously from about 12 to about 10. With carbonation curing regimes, the surface leachate pH values of the designed self-compacting concretes were lower compared with the standard curing regimes. Carbonation curing decreases the surface leachate pH value based on two stages mechanism, where the second stage plays a major role. The second stage is mainly characterized by reacting with Ca(OH)2 in surface pore solution and producing CaCO3 crystals which can prevent Ca(OH)2 crystals dissolution and reduce the pore solution OH– concentration (cOH–) so that reduces the surface leachate pH value. Based on leachate pH value tests, a simplified OH– ion diffusion coefficient determining method is proposed. Our results cast a new light on manufacture of marine artificial concrete reef with potential carbon neutralization capacity in the further.