Advanced Pore Structure Characterization of High-Volume Mineral Admixture Steam-Cured Mortar Using X-Ray Computed Tomography

Steam curing is a widely used method in the production of industrial precast concrete but it often leads to thermal damage that negatively impacts the material's long-term durability and mechanical strength. The use of supplementary cementitious materials (SCMs) has shown considerable promise in improving pore structure and alleviating these adverse effects. This study employs high-resolution X-ray computed tomography (X-CT) to thoroughly assess how steam curing temperatures and various subsequent curing regimes influence the pore characteristics of mortars containing high volumes of mineral admixtures. The results shows that steam-cured specimens under water curing (ST8012-WA) achieved a compressive strength of 51.72 MPa and flexural strength of 5.85 MPa, representing improvements of 9% and 19.8%, respectively, compared to natural curing (ST8012-NA: 47.32 MPa and 4.88 MPa). The standard-cured specimen (SD) exhibited the highest compressive strength of 54.18 MPa, highlighting the detrimental effects of elevated steam curing temperatures. The findings reveal that higher steam curing temperatures result in increased porosity and decreased mechanical strength, challenges that can be effectively mitigated through appropriate postcuring techniques. Notably, water curing following steam curing proves especially effective in reducing pore size variability and improving the material's durability. This research offers new insights into the intricate relationships among curing temperature, pore morphology, and mechanical performance, providing practical recommendations to optimize the quality and longevity of steam-cured precast concrete components.