Investigating the effect of accelerated carbonation curing duration on Portland and pozzolana cement‐based concrete

Abstract Accelerated carbonation curing (ACC) has emerged as a viable method to improve the sustainability and durability of construction materials, especially in precast concrete applications. The curing period is a crucial component affecting the efficacy of ACC and determines material performance. This study systematically examines the effects of carbonation curing periods, from 3 to 24 h, to determine the best period by evaluating CO 2 absorption, carbonation depth, microstructural attributes (using x‐ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry [MIP]), compressive strength, and permeation qualities (water absorption and sorptivity). Microstructural examination demonstrated a notable alteration in the morphology of the C–S–H gel, transitioning from an initially fibrous structure in water‐cured specimens to a flat denser structure in carbonated specimens, flat form containing embedded calcite crystals. The MIP results demonstrated a refinement of the pore structure, marked by the transformation of large void sizes into capillary sizes in carbonated specimens, thereby improving compressive strength and overall durability. The experimental results indicate that the most favorable curing durations are 12 h for ordinary Portland cement (OPC) and 15 h for Portland pozzolana cement (PPC); these findings contribute to a better understanding of the relationship between curing duration and concrete performance, offering valuable insights into optimizing strength, durability, and microstructural refinement for both OPC and PPC concrete systems.