纳米偏高岭土水泥浆在水化早期的内部结构建立

The Internal Structural Build-up of Cement Paste with Addition of Nano-Metakaolin in Early Hydration

考虑水胶比(0.40、0.45、0.50)、NMK掺量(0、1%、3%、5%、7%)、减水剂掺量(0、0.04%、0.08%,0.12%)及温度(10℃、20℃、30℃、40℃)的影响,采用静态屈服应力试验方法和小振幅振荡剪切试验方法获得了纳米偏高岭土(NMK)水泥浆静态屈服应力、储能模量等参数,通过静态屈服应力和储能模量随时间的演变规律讨论了水化早期(10~90 min)NMK水泥浆内部结构的建立过程.试验结果表明:NMK能够促进水泥浆在水化早期的内部结构建立.在水化90 min内,掺3%NMK水泥浆静态屈服应力的平均增长速率约为普通水泥浆的2倍;掺7%NMK水泥浆储能模量的平均增长速率约为普通水泥浆的4倍.水胶比越高、减水剂掺量越大,NMK水泥浆内部结构建立速率越低;NMK加速了不同温度环境中水泥浆内部结构的建立;温度升高,NMK水泥浆静态屈服应力和储能模量的增长速率增大.

Considering the effects of water to binder ratio(0.40,0.45,0.50),NMK contents(0,1%,3%,5%,7%),superplasticizer dosage(0,0.04%,0.08%,0.12%)and temperature(10°C,20°C,30°C,40°C),the static yield stress test method and small amplitude oscillation shear test method were used to obtain the parameters of static yield stress and storage modulus of nano-metakaolin(NMK)cement paste.The internal structural build-up of NMK cement paste in early hydration(10-90 min)was discussed by the evolution of static yield stress and storage modulus with time.The test results show that NMK promote the internal structural build-up of cement paste in the early hydration period.Within 90 min of cement hydration,the average growth rate of static yield stress of 3%NMK cement paste was about twice that of ordinary cement paste;the average growth rate of storage modulus of 7%NMK cement paste was about 4 times that of ordinary cement paste.The higher the water to binder ratio or the higher the superplasticizer content,the lower the growth rate of internal structural build-up of NMK cement paste;NMK accelerates the build-up of internal structure of cement paste in different temperature environment;an increasing temperature increases the growth rate of static yield stress and storage modulus of NMK cement paste.