CO2-Cured Fiber-Reinforced Board from Low-Calcium Clinker: Key Synthesizing Factors, Carbonation Products, and Comparison to Autoclaved Calcium Silicate Board

AbstractCO2-cured fiber-reinforced boards (CFBs) were fabricated from low-calcium clinkers (CaO content from 48.0% to 53.5%) by CO2 curing. Key synthesizing factors, including clinker composition, compaction pressure, water content, carbonation duration, carbonation temperature, and partial pressure of CO2, were investigated. Further, a performance comparison between CFB and autoclaved calcium silicate board (ACSB) was made. The results showed that the CFB with water-saturated flexural strength of 17.8 MPa, CO2 sequestration content of 18%, water adsorption of 9.2%, and bulk density of 2,059 kg/m3 was successfully prepared. CFBs, prepared at the compaction strength of 10 MPa, water content of 16%–18%, carbonation temperature of 50°C, and CO2 partial pressure of 0.3 MPa, were preferred to reach superior performance. CFB showed slightly higher water-saturation flexural strength, 59.3% lower water adsorption, and 22.5% lower calcium carbonates induced CO2 emission in comparison with ACSB. Owing to the higher increase in solid weight and volume during carbonation, CFB is much denser than autoclaved ACSB. Rhombohedral crystals of calcite could be observed in CFB, rather than the crystals of vaterite (cauliflower-like) and aragonite (needle-like), although diffraction signals of the latter two were detected.