Enhancing carbonation resistance of low-activity coal gangue-based LC3 cementitious materials with Ca(OH)2 and gypsum additives

The utilization of coal gangue in limestone calcined clay cement (LC3) has been limited by its relatively low activity and poor carbonation resistance. This research evaluates the effects of adding Ca(OH)2 and gypsum to enhance the carbonation resistance and mechanical properties of coal gangue-based LC3. Coal gangue-based LC3 with 60 % coal gangue replacement exhibits limited carbonation resistance, with a carbonation depth of 19.3 mm and a post-carbonation compressive strength of 20.4 MPa. However, with the incorporation of 7.15 % Ca(OH)2 and 10 % gypsum, the carbonation depth reduces to 17.0 mm and the compressive strength increases to 31.9 MPa. In the composite with 30 % coal gangue, the addition of 20 % gypsum results in a carbonation depth of 10 mm and a compressive strength of 39.3 MPa. These findings provide crucial insights for the optimization and industrial application of sustainable cement materials.