10℃条件下纳米C-S-H掺量对水泥早期水化的影响

Effects of Nano C-S-H Content on Early Hydration of Cement at 10℃

目的探究10℃条件下不同掺量纳米C-S-H对水泥早期水化进程及强度发展的影响,并分析其早强剂作用机理。方法通过溶液共沉淀法制备纳米C-S-H悬浮液,将其掺入到普通硅酸盐水泥中,在10℃条件下进行养护,分析其对水泥凝结时间、抗折强度、抗压强度的影响;通过XRD、TG等检测手段分析水泥的水化进程及对水化产物的影响。结果掺入0.05%纳米C-S-H,可使水泥初凝时间缩短9.9%,终凝时间缩短10.4%;24 h时抗折强度和抗压强度分别提高了34%和33.5%。纳米C-S-H的掺入造成水泥3 d抗折强度略有降低。水化产物中Ca(OH)2质量分数在12 h、16 h和24 h时较参比样分别提高了17.6%、21.3%和29.6%。结论在10℃条件下,纳米C-S-H的加入能够有效促进C 3S和C 2S的水化过程,形成更多的水化产物,从而缩短水泥凝结时间,提高24 h内水泥砂浆强度,28 d强度没有显著降低。

The influence of nano C-S-H on the hydration process and development of early strength of cement at 10℃was explored,and the mechanism of its early strength enhancement was analyzed.In this paper,nano C-S-H suspension was prepared by solution coprecipitation method,and it was mixed with ordinary Portland cement.The effects of nano C-S-H on setting time,flexural strength and compressive strength at 10℃were analyzed;Its effects on hydration process and hydration products were tested by XRD and TG.The initial setting time and final setting time were reduced by 9.9%and 10.4%when 0.05%of nano C-S-H was doped.Corresponding,the 24 h flexural strength and compressive strength increased by 34%and 33.5%.The addition of nano C-S-H resulted in a slight decrease in the 3 d strength.The content of Ca(OH)2 at 12 h,16 h and 24 h increased by 17.6%,21.3%and 29.6%,respectively,compared to the reference specimen.The addition of nano C-S-H can effectively promote the hydration process of C 3S to form more hydration products,shorten the setting time of cement and improve the strength of cement mortar within 24 h at 10℃.And no obvious decrease in 28 d compressive strength was observed.