Pre-bio-carbonation method for using reactive MgO for rapid pavement repair and the carbonation mechanisms

Abstract

For road repair, a rapid method is much desired to minimize traffic disclosure. This study proposes a new method for granular materials to gain strength rapidly. Using microbial carbonation for reactive MgO cement (RMC), a pre-bio-carbonation method is proposed to allow RMC treated materials to gain 80% of the final strength in 2 h when 8% RMC content is used. In this proposed method, a biosolution that has been premixed several hours before application is applied together with RMC for soil treatment. The carbonates that have already been generated from a urea hydrolyzation using ureolytic bacteria allow an immediate carbonation of RMC. As a result, the strength of the bio-carbonated RMC treated materials gain strength rapidly due to a quick formation and crystallinity of hydrated magnesium carbonates. To study the mechanisms and effectiveness of this method, laboratory tests were carried out to evaluate the strength development with time in the RMC treated granular materials and the conditions controlling the amount of strength gain. The influence of biosolution mixing time on the strength gain and the microstructural development of the bio-carbonated RMC are also discussed.