水泥-粉煤灰体系早龄期液相离子浓度与电导率的关系

Relationships Between Liquid Ion Concentration and Electrical Conductivity During the Early Hydration of Cement-Fly Ash System

通过离心和高压萃取法分别提取水泥-粉煤灰体系1h内和5~24h的液相,采用电感耦合等离子体发射光谱仪(ICPOES)、pH计和电导率测试仪分别测试液相离子浓度、pH值和电导率,并探究了粉煤灰掺量对体系液相离子浓度、pH值和电导率的影响。结果表明:随水化时间延长,水泥-粉煤灰体系早龄期液相中K^+浓度先降低后上升,Na^+、SiO_4^(4-)浓度和pH值逐渐上升,5h左右Ca^(2+)和SO_4^(2-)浓度达到峰值,10h左右AlO_2^-浓度达到峰值;随粉煤灰掺量增加,液相中各离子浓度和电导率呈降低趋势,根据液相电导率变化规律将体系早龄期水化进程分为溶解期、诱导期和加速期三个阶段;液相电导率与离子总浓度成正相关,主要受K^+、Na^+和OH^-浓度影响,高掺量(50%)粉煤灰对单一离子与电导率之间相关性的影响较为显著。

Based centrifugation and high-pressure extraction,liquid phase of cement-fly ash system between 0—1 hand 5—24 h were extracted respectively.In order to explore the influence from different dosage of fly ash on the ion concentration and the conductivity in liquid phase of system,the ion concentration and electrical conductivity were analysed by inductively coupled plasma optical emission spectrometry（ICP-OES）,pH meter and conductivity meter.The results show that along hydration time,K＋concentration present downward trend firstly and then increased gradually,Na＋and SiO4^4- concentration and pH increased gradually,Ca^2＋ and SO4^2- concentration present on the contrary with K＋concentration reaching the peak value around 5 h,AlO2^- concentration present similarly with Ca^2＋ and SO4^2- concentration arriving the peak value around 10 h.Ions concentration and conductivity in liquid phase of cement-fly ash system are decreased along with the increasing dosage of fly ash（0%,10%,30% and 50%）,and three stages（dissolution,induction,and acceleration）during the early hydration of cement-fly ash system are identified according to the characteristics of the laws of liquid conductivity change.Liquid conductivity are positively correlated with the total ion concentrations,mainly affected by K^＋,Na^＋ and OH^-,and the relationships between single ion and the liquid conductivity are influenced significantly by high dosage（50%）of fly ash.