矿物掺合料和化学外加剂对胶凝材料浆体的流变参数的影响

Effect of mineral and chemical admixtures on rheological parameters of binder paste

基于最优化方法,给出使用同轴双圆柱流变仪来获取胶凝材料浆体的Bingham流变参数的途径;探究五种矿物掺合料(粉煤灰、矿渣粉、硅灰、石英粉、粉煤灰微珠)和两种化学外加剂(减水剂与引气剂)对胶凝材料浆体流变参数的影响。研究结果表明:矿物掺合料等体积替代水泥相对于等质量替代水泥,对降低浆体的屈服应力和塑性黏度有利。粉煤灰可降低浆体的屈服应力和塑性黏度;矿渣粉和石英粉可降低高水胶比浆体的屈服应力和塑性黏度,但增大低水胶比浆体的屈服应力和塑性黏度;硅灰可显著提升浆体的屈服应力;粉煤灰微珠可降低浆体的塑性黏度但增大其屈服应力。减水剂可降低浆体的屈服应力和塑性黏度;引气剂可降低浆体的塑性黏度。矿物掺合料和化学外加剂对胶凝材料浆体的Bingham流变参数的影响,取决于水胶比、矿物掺合料或化学外加剂的掺量、矿物掺合料颗粒粒径、粒形和水化活性等因素,因此使得胶凝材料浆体的流变参数随着矿物掺合料和化学外加剂种类和掺量的变化,表现出非线性特征。

Based on the optimization method, the calculation methods of the Bingham rheological parameters of binder paste were attained from the measuring results of coaxial cylinder rheometer.The effects of five mineral admixtures(fly ash, ground granulated blast-furnace slag or GGBS, silica fume, quartz powder and fly ash cenosphere) and two chemical additives(water reducing agent or WRA and air entraining agent) on the rheological parameters of binder paste were analyzed.The results show that compared to the substitution of the same mass, the substitution of cement by the same volume of mineral admixture is more beneficial for reducing the yield stress and plastic viscosity of binder paste.Fly ash can reduce the yield stress and plastic viscosity of binder paste;GGBS and quartz powder may reduce the yield stress and plastic viscosity of binder paste with high water-binder(W/B) ratio, but they may increase the two quantities of binder paste with low W/B ratio;silica fume may significantly increase the yield stress of binder paste;cenosphere may reduce the plastic viscosity but enhance the yield stress of binder paste.WRA can reduce the yield stress and plastic viscosity of binder paste;air entraining agent can reduce the plastic viscosity of binder paste.The effects of mineral admixtures and chemical additives on the rheological parameters of binder paste depend on those factors such as the dosage, W/B ratio of paste, particle size, particle morphology, hydration activity, etc.of mineral admixtures.Furthermore, the rheological parameters of pastes varying with the dosage and kinds of mineral admixtures or chemical admixtures appeared to be nonlinear under the influence of these factors.