Synergy of Carbon Sequestration and Solid Waste Resource Utilization: A Review on Carbonation Behavior of Fly Ash Concrete

In recent years, the application of fly ash concrete (FAC) has witnessed a remarkable expansion worldwide. Compared with ordinary Portland cement (OPC), the incorporation of fly ash (FA) reduces the consumption of cement, realizes solid waste resource utilization, and concurrently cuts down carbon emissions from cement production, thus yielding notable environmental benefits. With the gradual popularization of concrete carbon sequestration technology, the research focus of academic circles on concrete carbonation behavior has shifted from the traditional orientation of “optimizing carbonation resistance” to the new direction of “enhancing carbon sequestration efficiency”. Nevertheless, current research on the mechanical properties, durability, and other behaviors of FAC after carbonation remains scarce, lacking systematic and in-depth exploration, and the mechanism underlying the impacts of carbonation on material properties still requires further systematic collation and generalization. Consequently, research on the carbonation behavior of FAC holds profound academic significance and promising application value. This paper reviews the microscopic mechanisms and influencing factors of FAC carbonation; summarizes and analyzes the effects of FAC carbonation on its various properties and microscopic pore structure; introduces the innovative breakthroughs in FAC technology in recent years; and finally, prospects future research directions. It is anticipated to provide a valuable reference for subsequent relevant studies.