石灰石粉在水泥浆体结构建立中的作用机理

Action Mechanism of Ground Limestone in Structural Build up of Cement Paste

采用Zeta电位仪、微量热仪、维卡仪、旋转黏度计和静态称重仪测试了新拌水泥-石灰石粉浆体Zeta电位、水化放热速率、凝结时间、结构新建能和动态屈服应力、静态屈服应力,研究了石灰石粉在新拌水泥浆体静置和非静置状态下结构建立中的作用机理.结果表明:石灰石粉在新拌水泥浆体中的主要作用与浆体是否处于静置状态有关;静置状态下,随石灰石粉掺量(质量分数,下同)增加,水泥浆体Zeta电位绝对值减小,凝结时间减少,诱导期缩短、加速期提前和放热量增加,静态屈服应力增大,石灰石粉在水泥浆体中的微晶成核作用占主导;非静置状态下,随石灰石粉掺量增加,新拌水泥浆Zeta电位绝对值减小,动态屈服应力、结构新建能减小,石灰石粉在水泥浆体中的级配和稀释作用占主导;非静置状态下,若新拌水泥浆体只受微动的影响,随石灰石粉掺量增加,水泥浆体剪切应力增加速率先增大后减小,在石灰石粉掺量为20%时达到最大值.

Zeta potential,setting time,structure reconstruction energy and dynamic yield stress,and static yield stress of cement-ground limestone paste were determined by Zeta potential analyzer,VEKA instrument,rotary viscometer and static weighing instrument,and the action mechanisms of ground limestone were revealed in fresh cement paste under static and non static state.The results show that the main action of ground limestone in the fresh cement paste is related to its state.The setting time and absolute value of Zeta potential decrease,the induction is shortened,the acceleration period is advanced and heat discharge increases,and the static yield stress increases for cement paste with the ground limestone content(by mass,the same below)increasing during the resting state in which the action of nucleation of the ground limestone are dominant in the fresh cement paste.The absolute value of Zeta potential,dynamic yield stress and new building energy of the cement paste decrease with ground limestone content increasing during the non resting state in which the action of filling and gradation of the ground limestone are dominant in the fresh cement paste.If the fresh cement paste is only affected by slight disturbance,the growing rate of shear stress of the cement paste increases firstly and then decreases with the ground limestone content increasing,which achieves maximum while the ground limestone content is 20%.