为减少制备硅酸钙板对矿物原浆资源的损耗和提高对固体废弃物的协同利用效果,试验以电石渣-煤基固废胶凝体系为原料来研制高强度的纯固废硅酸钙板,并通过热重-差示扫描量热法、X射线衍射测试来分析硅酸钙板中生成的主要矿物成分及不同配比对硅酸钙板的强度变化关系.研究表明:在水灰比为0.3的条件下,使用电石渣完全替代水泥,将粉煤灰和硅灰按1:1的质量比互掺调制所得的混合胶凝体系最终制得托贝莫来石型纯固废硅酸钙样板.在硅灰占原料的质量分数为0~10%范围内,样板抗折强度随硅灰添量增加而升高,硅灰添量为10%时样板达到最大抗折强度,不同粒径的原料颗粒相互填充,板内晶体与水化胶凝体相互咬合,最终使得样板力学性能得到大幅提升;样板的抗折强度随着NaOH添量的增加呈现先增后降的趋势,NaOH添加质量分数为4%时样板板面平滑,强度达到最大值11.8 MPa,该添量为NaOH的最佳添量,通过扫描电镜分析发现加入4% NaOH时对该胶凝体系的水化反应起到最佳激发作用,且样板料坯的微观结构对其最终的力学性能有重要影响,但不起决定性作用,其中决定其最终强度的是板坯内水化胶凝体的数量、形态以及其相互间的联结方式.
The purpose of this study was to reduce the loss of raw material calcium in the preparation of calcium silicate board and improve the synergistic utilization efficiency of solid waste. This test used a carbide slag-coal-based solid waste gelling system as the raw material to develop high-strength pure solid waste calcium silicate board. The main mineral components produced in the calcium silicate board and the variation in calcium silicate board strength with different proportioning were analyzed using thermogravimetry-differential scanning calorimetry (TG-DSC) and X-ray diffraction (XRD) test. The results show that the use of carbide slag completely substitutes cement. Fly ash and silica fume were mixed in mass ratio of 1:1 to prepare a mixed gelling system. Finally, the tobago mullite pure solid-waste calcium silicate template could be made with a water-cement ratio of 0.3. When silica fume was added in the mass percent of 0-10%, the bending strength of the template strengthened. Flexural strength of the calcium silicate board reached maximum when the amount of silica fume was 10%. Here, raw material particles composed of various dimensions were fully mixed. Also, crystals and hydrated gels closely interacted. Thus, the mechanical properties of the calcium silicate board significantly improved. The bending strength of the calcium silicate board tends to increase first, and then decrease with increasing NaOH dosage. The surface of the calcium silicate board was smooth when the mass percent of NaOH was 4% and mechanical strength reached a maximum of 11.8 MPa. This proved to be the optimum amount of added NaOH. The hydration reaction of the gelling system can achieve the best stimulating effect when 4% NaOH is added using scanning electron microscopy analysis. Moreover, the microstructure of material billets has an important impact on the final mechanical properties. However, the mechanical strength of the pre-cured calcium silicate board is not decisive of the final mechanical properties. The internal hydration gel number, shape, and connection are linked to each other inside the calcium silicate board; this is the key factor in determining the final mechanical properties of the calcium silicate board.