甲酸钙对轻烧氧化镁水泥基材料水化和膨胀性能的影响

Effect of calcium formate on the hydration and expansion properties of light-burned magnesium oxide cement-based materials

轻烧氧化镁(LBM)作为一种补偿水工大体积混凝土温降收缩的膨胀剂,其膨胀性能与氧化镁水化密切相关。水工混凝土冬季施工常常要用到早强剂,甲酸钙(CF)是目前应用最广的一种早强剂。关于早强剂对水泥水化影响的研究很多,但是缺乏关于早强剂对掺膨胀剂水工混凝土膨胀性能影响的研究。通过测定凝结时间、水化热、线性膨胀和抗压强度等性能,结合XRD和SEM微观表征,系统地研究了CF对LBM水泥基材料水化及膨胀性能的影响。结果表明,在蒸馏水中,掺CF抑制LBM的水化,延缓了其凝结。然而在水泥基材料中,CF加速了LBM的水化,提升了其膨胀性能。XRD和SEM分析显示,掺入CF促进Ca(OH)_(2)和C-S-H凝胶生成,从而加速了MgO的水化。

Light-burned magnesia(LBM)as a kind of expansion agent to compensate the thermal shrinkage of hydraulic mass concrete,its expansion performance is closely related to the hydration of magnesium oxide.Accelerator is often used in hydraulic concrete construction in winter,and calcium formate(CF)is the most widely used accelerator at present.There were many studies on the effect of accelerator on cement hydration,but there was a lack of research on the effect of accelerator on expansion agent in cement-based materials.In this paper,the effects of calcium formate on the hydration and expansion properties of light-burned magnesia cement-based materials were systematically studied by measuring the properties such as setting time,hydration heat,linear expansion and compressive strength,combined with the micro characterization of XRD and SEM.The results showed that calcium formate in distilled water inhibited the hydration of light-burned magnesia and delayed its setting time.However,in cement-based materials,calcium formate accelerated the hydration of light-burned magnesia and increases its expansion properties.XRD patterns and SEM images showed that the addition of CF resulted in the formation of Ca(OH)_(2) and C-S-H gel,and promoted the hydration of magnesium oxide.