石膏对高贝利特硫铝酸盐水泥水化的影响

Effect of Gypsum on Hydration of High Belite Sulphoaluminate Cement

研究了石膏掺量对高贝利特硫铝酸盐水泥抗压强度的影响,利用XRD和SEM进行了水泥的水化产物和微观结构分析。强度试验结果表明,石膏掺量存在一个最佳值,当石膏系数M值为0.74时,可以得到较高的水泥强度。XRD和SEM分析表明,高贝利特硫铝酸盐水泥的水化产物为AFt、AFm、C-S-H凝胶和铝胶等,未发现Ca(OH)2。当石膏掺量不足时,生成的AFt会发生转化;而当石膏掺量过大时,又会影响到水泥的水化,进而影响强度。适宜的石膏掺量能够促进C4A3-S、-βC2S的水化,生成更多的水化产物,形成较为致密的结构,从而提高水泥强度。

The effect of different gypsum proportion on the compressive strength of high belite sulphoaluminate cement was researched. In addition, the hydration process and microstructure of cement were analyzed by XRD and SEM. The results of mechanical test indicate that it exists a optimal value of gypsum proportion. The optimal of proportion the clinker calcined in this experiment, gypsum is M = 0.74. The XRD and SEM results show that the main hydration products of high belite sulphoaluminate cement are ettringite, calcium monosulphoaluminate hydrate, silicate hydrate gel, aluminium hydrate gel, and no calcium hydroxide is found. The proper mixing of gypsum in cement can greatly increase the hydration speed of C4A3S^- and β-C2S, accelerate the formation of AFt and C-S-H, and hardened cement paste to get a dense structure in early stage which makes it have a high strength. Large quantities of AFm will form or the hydration of C4A3S^- and β-G2S will be inhibited if the gypsum proportion is too large or too small, which lead to the compressive strength of cement increases slowly or appears the phenomenon of reduction.