化学外加剂对粉煤灰-矿渣-水泥胶凝体系的激发作用

Excitation Function of Chemical Admixture on Fly Ash-Slag-Cement Cementitious System

为提高粉煤灰-矿渣-水泥充填胶凝体系早期强度,选取10种激发剂,通过单掺及复掺试验,研究激发剂的早强性能,并获得最优配比,利用XRD、SEM、EDS手段分析了胶凝体系的水化产物及复合激发剂作用机理。结果表明:单掺激发剂时,当掺量≤1.4%,早强效果较优的依次为:NaCl>Na_2CO_3>CaSO_4·2H_2O>Na_2SiO_3·9H_2O>三乙醇胺,复掺激发剂最佳配比为:NaCl、三乙醇胺分别为胶凝材料总质量0.9%和0.03%,硫铝酸盐水泥、CaSO_4·2H_2O均为水泥熟料质量5%,胶砂试样3 d强度比空白样提高191.7%,28 d强度与空白样相差不大;胶凝体系受激发主要水化产物为C-S-H凝胶、水化氯铝酸钙和钙矾石,C-S-H凝胶构成了试样的强度主体,针状钙矾石与片状水化氯铝酸钙交错生长,具有加筋、填充作用,使微观结构更加密实、紧凑,提高了早期强度。

In order to improve the early strength of fly ash-slag-cement clinker filling cement system,the early strength performances were studied though single mix and duplicate mixes experiments based on 10 activating agents,the optimum proportion was obtained eventually.Hydration products and activation mechanism were analyzed adopting the approach of XRD,SEM and EDS.The results indicate that:when content of activating agent of single mix is less then or equal to 1.4%,the sequencing of activation effect is:NaCl>Na2C03>CaS04.2H20>Na2Si03.9H20>triethanolamine,the duplicate mixes optimal formula was identified a s:major activating agent NaCl and triethanolamine account for 0.9%and 0.03%of total mass of cementitious material,sulphoaluminate cement and CaS04?2H20 both account for 5%of cement clinker,which made the 3 d compressive strength of the specimen improve by 191.7%,while the 28 d strength was basically the same as that of blank specimen.The major hydration products of filling cementitious systems under activation are C-S-H gel,calcium aluminate chloride hydrate and ettringite,among which,C-S-H gel contributed most to specimen strength growth,aciculate ettringite and flaky calcium aluminate chloride hydrate interlaced with one another,playing the role of reinforcement and filling,making the microstructure more compact,improved the early strength.