Characterization of the Cement-Based Composites Incorporating Ground Pond Ash Using Thermogravimetric Analysis

The global decline in the numbers of coal-fired thermal power plants has reduced the availability of coal fly ash (CFA), prompting the search for alternative supplementary cementitious materials (SCMs). Pond ash, a sediment formed from fine coal particles settling in the water, retains significant silica content that offers pozzolanic properties suitable for cement hydration, making it a promising alternative SCM to mitigate the environmental impact of cement production and address the CFA shortage. However, pond ash is usually underutilized due to its off-standard classification and impurities. This study explores the feasibility of using pre-processed ground pond ash (GPA) as a partial substitute for ordinary Portland cement (OPC) in cement-based composites. Raw pond ash was pre-processed through ball milling to achieve a comparable fineness to CFA. Four GPA substitution levels (10%, 20%, 30%, and 40%) and three curing ages (2, 7, and 28 days) were evaluated through the correlation of compressive strength testing and thermogravimetric analysis (TGA). The results identified 10% GPA substitution as optimal, achieving the highest 28-day compressive strength. At 28 days, TGA analysis showed portlandite contents of 3.49%, 2.66%, 2.50%, 2.38%, and 2.18% for P100G0, P90G10, P80G20, P70G30, and P60G40, respectively, with corresponding C-S-H gel contents of 4.21%, 4.62%, 4.29%, 3.73%, and 3.69%, indicating enhanced hydration products. This study demonstrated that GPA, with proper pre-treatment and optimized substitution ratios, can substitute OPC effectively by up to 20%, promoting sustainable and durable construction practices.