低活性矿渣内养护水泥砂浆的水化特性和微观结构分析

Hydration Characteristics and Microstructure Analysis of Low-activitySlag Internal Curing Cement Mortar

用预吸水饱和面干的低活性矿渣作为内养护材料替代细集料,研究在低活性矿渣内养护作用下高性能砂浆的力学性能及水化特性,并从微观尺度揭示其内养护作用机理。研究结果表明:在内养护的作用下,随着低活性矿渣掺量的增加,砂浆早期强度下降,但随着龄期的延长,砂浆中后期强度降低幅度小于早期降低幅度,建议低活性矿渣合适掺量为细集料质量的15%~25%。低活性矿渣内养护对砂浆电阻率发展影响明显,在凝结硬化前,浆体电阻率随低活性矿渣掺量的增大而增大;在凝结硬化后,浆体电阻率随低活性矿渣掺量的增大而减小。其中砂浆水化进程的溶解结晶期延后,诱导凝结期、硬化加速期和硬化减速期均有所提前;由于低活性矿渣的内养护效应,砂浆的界面过渡区比普通砂浆更致密均匀,优化了浆体的界面过渡区结构。

The mechanical properties and hydration characteristics of high-performance mortar under the internal curing effect of low-active slag were studied by using pre-absorbent saturated low-active slag as internal curing materials to replace fine aggregate,and the internal curing mechanism was revealed from the micro scales.The results show that under the effect of internal curing,the early strength of mortar decreases with the increase of low-activity slag content,but with the extension of age,the strength reduction in the middle and late stages of mortar is smaller than that in the early stage.It is suggested that the appropriate content of low-activity slag is 15%-25%of the fine aggregate quality.The internal curing of low active slag has obvious influence on the resistivity development of mortar.Before setting hardening,the resistivity of mortar increases with the increase of low active slag content.After setting hardening,the slurry resistivity decreases with the increase of low active slag content.The dissolution crystallization period of mortar hydration process is delayed,and the induced setting period,hardening acceleration period and hardening deceleration period are all advanced.Due to the internal curing effect of low active slag,the interface transition zone of mortar is more dense and uniform than that of ordinary mortar,which optimizes the interface transition zone of mortar.