养护温度与脱硫石膏掺量对RPC性能的影响

Effect of curing temperature and desulfurization gypsum content on performance of RPC

以普通硅酸盐水泥、脱硫石膏、矿渣等制备了活性粉末混凝土(RPC),研究了养护温度(20、45、70℃)和脱硫石膏掺量(2%~7%)对RPC强度和膨胀率的影响,并进行了XRD和SEM分析。结果表明:当养护温度为20℃时,随着脱硫石膏掺量的增加,试件的28 d抗折与抗压强度均先增大后减小;当养护温度为45℃时,随着脱硫石膏掺量的增加,试件的28 d抗折强度增大,28 d抗压强度先增大后减小;当养护温度为70℃时,试件的28 d抗折与抗压强度均增大;当脱硫石膏掺量相同时,随着养护温度的提高,试件的28 d抗折与抗压强度基本呈增大趋势;脱硫石膏掺量越高,试件的膨胀率越大;养护温度越高,试件趋于稳定时的膨胀率越低;在RPC中掺入适量石膏,并辅以适宜的养护温度,可有效加快水泥和矿渣的水化进程,生成钙矾石,进而改善RPC的强度和膨胀性能。

Reactive powder concrete(RPC)was prepared by using ordinary Portland cement,desulfurization gypsum,slag,etc.The effects of curing temperature(20,45,70℃)and desulfurization gypsum content(2%~7%)on the strength and expansion rate of RPC were studied,and XRD and SEM analysis were conducted.The results show that when the curing temperature is 20℃,with the increase of desulfurization gypsum content,the 28 d flexural strength and compressive strength of the specimen first increase and then decrease.When the curing temperature is 45℃,with the increase of desulfurization gypsum content,the 28 d flexural strength of the specimen increases and the 28 d compressive strength first increases and then decreases.When the curing temperature is 70℃,the 28 d flexural strength and compressive strength of the specimen increase.When the content of desulfurization gypsum is the same,with the increase of curing temperature,the 28 d flexural strength and compressive strength of the specimen basically show an increasing trend.The higher the content of desulfurization gypsum,the greater the expansion rate of the specimen.The higher the curing temperature,the lower the expansion rate of the specimen when it tends to stabilize.Adding an appropriate content of gypsum to RPC,accompanied by an appropriate curing temperature can effectively promote the hydration process of cement and slag,generate ettringite,and improve the strength and expansion properties of RPC.