钢渣-煤基固废可控低强度材料制备及热力学分析

利用NaOH、Na₂SO₄协同碱激发煤矸石(CG)、钢渣(SS)、粉煤灰(FA)制备无水泥可控低强度材料(CLSM)。利用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)分析了CLSM的微观结构和相组成。结果表明，Ca/(Ca+Si)的摩尔比与材料的7 d、28 d无侧限抗压强度比值存在线性关系，当Ca/(Ca+Si)摩尔比大于0.407时，7 d即可达到28 d无侧限抗压强度的70%以上，该材料具有早强特性。当粉煤灰质量掺量在40%以下时，CLSM工作性(流动性)满足ACI规范要求，不同质量配比的SS/FA改变了CLSM体系中反应产物的相组成，产物中钙矾石与水化硅酸钙(C-S-H)凝胶的密实嵌合结构为材料力学性能提供了微观结构基础。最后，基于吉布斯自由能最小化方法，模拟了水化产物中两种晶型水化硅酸钙的生成量。

Preparation and Thermodynamic Analysis of Steel Slag-Coal Based Solid Waste Controllable Low-Strength Materials

Cement-free controllable low strength material (CLSM) was prepared by coal gangue (CG), steel slag (SS) and fly ash (FA) under the condition of NaOH, Na₂SO₄ synergistic alkali-activation. The microstructure and phase composition of CLSM were analyzed by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) technique. The results show that there is a linear relationship between the molar ratio of Ca/(Ca+Si) and 7 d, 28 d unconfined compressive strength ratio. When the molar ratio of Ca/(Ca+Si) is greater than 0.407, the unconfined compressive strength of CLSM curing for 7 d can reach more than 70% of that of 28 d, which shows the material has early strength feature. When the fly ash is below 40% (mass fraction), the CLSM performance (flow ability) meets the requirements of ACI specification. The different mass proportions of SS/FA change the phase composition of the reaction products in the CLSM system, and the dense chimeric structures of ettringite and calcium silicate hydrate (C-S-H) gel provide the microstructure ground for mechanical properties. Finally, based on the Gibbs free energy minimization method, the amount of two crystal types of hydrated calcium silicate in the hydration products is simulated.