高掺量煤气化渣制备免蒸压加气混凝土

To realize the resource utilization of Coal gasification slag, aerated concrete is prepared with coal gasification slag as the main raw material, high salt wastewater as mixing water, supplemented by Ca(OH)₂ and NaOH. In the early stage, the coal gasification slag based cementitious materials were prepared by orthogonal test and single factor test. The proportion with the highest strength as the propor⁃ tion of the aerated concrete matrix material was selected. The effects of hydrogen peroxide and Calcium stearate on the physical and me⁃ chanical properties and pore structure of aerated concrete were mainly studied, and the hydration products of aerated concrete under differ⁃ ent curing temperatures were analyzed by microscopic detection methods such as XRD and SEM. The results show that based on the quality standard of coal gasification slag, 10% NaOH and 10% Ca (OH)₂ are added externally to the total amount of coal gasification slag, and the mixed water is high salt wastewater. At this point, the 28-day compressive strength of the coal gasification slag based cementitious ma⁃ terial is the highest, reaching 68.8 MPa. Non-autoclaved aerated concrete is prepared by adding hydrogen peroxide as an air entraining agent and calcium stearate as a foam stabilizer to the cementitious material. As the content of hydrogen peroxide increases, the pore size of aerated concrete gradually increases and the number of connected pores increases, resulting in a decrease in both dry density and strength. After adding an appropriate content of calcium stearate, the pore distribution becomes more uniform and the pore shape tends towards a regular circular shape, resulting in a significant increase in strength. The content of hydrogen peroxide and Calcium stearate is 5% and 1.5% respectively, and the compressive strength of aerated concrete is the highest when the curing temperature is 80 ℃, reaching 2.9 MPa. In addition, the corresponding dry density is 617.2 kg/m³. Micro analysis shows that the hydration products of high content coal gasification slag based aerated concrete are mainly C-S-H gel, C-A-H gel and zeolite. The hole wall is mainly composed of foil shaped C-S-H that intersects and overlaps with each other, with a small amount of randomly interwoven slender needle shaped C-S-H. These hydration products are cross-linked with each other, making the pore wall structure denser and contributing to the improvement of strength.