中低强度等级预拌混凝土的流变模型及其应用

Rheological Model of Medium-low Strength Grades Premixed Concrete and Its Application

针对中低强度等级混凝土,采用砂浆流变法建立了混凝土流变模型,通过ICAR、RST-SST流变仪测定混凝土和砂浆的流变参数,利用数据回归确定了模型中的待定参数,并对模型进行了验证。结果表明,该模型将混凝土视为砂浆和粗骨料组成的悬浮体,剩余砂浆厚度、骨料占比体积等变量可充分考虑粗骨料在砂浆中的悬浮状态及其对流变性的影响,变量在混凝土生产中的材料波动下易测定与获取。模型验证表明,模型预测值与实测值较为接近,无系统偏差,故模型可较为准确地反映混凝土流变特征,为中低强度等级预拌混凝土的生产控制提供指导。

Rheological model of medium-low strength concrete was proposed based on the mortar rheology method.The rheological parameters of concrete and mortar were measured by ICAR and RST-SST rheometer.The undetermined parameters of the model were determined by data regression and the model was verified.The experimental results show that the variables of residual mortar thickness and coarse aggregate volume fraction can fully consider the suspension state of coarse aggregate in mortar and its influence on rheological properties if regarding concrete as a suspension consisting of mortar and coarse aggregate.The variables are also easy to be measured and acquired under material fluctuation in concrete production.The modelled and experiment results are in accordance with each other without systematic deviation.Therefore,the model can accurately reflect the rheological characteristics of concrete and provide guidance for the production control of medium-low strength concrete.