乳酸钠对超硫酸盐水泥强度的影响及作用机理

超硫酸盐水泥是一种资源节约和环境友好型胶凝材料,但由于存在早期强度低等缺陷,限制了其推广应用。为提高超硫酸盐水泥早期强度,研究了乳酸钠掺量对超硫酸盐水泥强度的影响,通过ICP-OES、MIP、XRD、SEM等测试,分析了离子浓度、水化产物及微结构,并对相关机制进行了探讨。结果表明,超硫酸盐水泥中掺入少量乳酸钠能提高水泥强度,尤其是早期强度,但是掺量过高时其作用效果降低,甚至对强度不利。综合考虑早期强度和后期强度提高效果,乳酸钠掺量以0.25%(质量分数)左右为宜。乳酸钠提高超硫酸盐水泥强度的主要原因在于其能促进矿渣溶解,加快钙矾石和C-S-H等水化产物生成,从而改善水泥石微结构。

Effect and Mechanism of Sodium Lactate on Strength of Supersulfate Cement

Supersulfate cement is a kind of resource saving and environmentally friendly cementitious material, but its application is limited because of its low strength in early stage. In order to improve its early strength, the effect of sodium lactate content on the strength of supersulfate cement was studied, the ion concentration, hydration products and microstructure were analyzed by ICP-OES, MIP, XRD and SEM, and the related mechanism was discussed. The results show that the strength of supersulfate cement, especially the early strength, is improved by adding a small amount of sodium lactate, but it is detrimental to the strength when adding too much. Considering the increasing effect of early strength and late strength, the suitable content of sodium lactate is about 0.25% (mass fraction). The main reasonwhy sodium lactate improves the strength of supersulfate cement is that sodium lactate can promote the dissolution of slag, accelerate the formation of ettringite and C-S-H, and thus improve the microstructure of cement.