掺聚丙烯纤维粗骨料膏体流变性能及计算模型

Rheological properties and calculation models of coarse aggregate paste with polypropylene fiber

选取金川二矿区全尾砂和棒磨砂为实验材料,采用全面实验设计法,探究聚丙烯纤维对粗骨料膏体剪切应力及流变特性的影响;并根据实验数据建立关于纤维体积率(纤维掺量与密度之比)和长径比(纤维长度与直径之比)的流变特性计算模型,以期为掺纤维粗骨料膏体流变性能预测提供方法。研究结果表明:掺入聚丙烯纤维会弱化膏体的剪切稀化和剪切增稠现象,且随着聚丙烯纤维掺量不断增加,聚丙烯纤维粗骨料膏体越来越接近宾汉体;膏体的屈服应力和塑性黏度随掺入聚丙烯纤维体积率及长径比增大而增大,纤维体积率对屈服应力及塑性黏度的影响大于纤维长径比对屈服应力及塑性黏度的影响;与未掺聚丙烯纤维相比,掺入纤维的屈服应力增加率为2.28%~19.59%,塑性黏度增加率为5.66%~87.15%。计算模型表明屈服应力及塑性黏度与纤维体积率近似呈指数关系,与纤维长径比近似呈线性关系;最后,采用凡口铅锌矿全尾砂对计算模型进行验证,拟合方程复相关系数(R2)均大于0.95。

The effects of polypropylene fiber on the shear stress and rheological properties of coarse aggregate paste were investigated by using the comprehensive experimental design method,with the whole tailings and rod scrub in Jinchuan No.2 mining area as experimental materials.Based on the experimental data,the calculation models of the rheological properties of the fiber volume ratio and length-diameter ratio were constructed to provide a method for predicting the rheological properties of coarse aggregate paste mixed with fiber.The results show that shear thinning and shear thickening of paste will be weakened by adding polypropylene fiber,and with the increase of polypropylene fiber content,the coarse aggregated paste of polypropylene fiber is getting closer to Bingham.The yield stress and plastic viscosity of paste increase with the increase of volume fractions and lengthdiameter ratios of polypropylene fiber.The fiber volume ratio has a greater influence on the yield stress and plastic viscosity than the fiber length-diameter ratio.Compared with unincorporated polypropylene fiber,the increase rates of yield stress and plastic viscosity are 2.28%−19.59%and 5.66%−87.15%,respectively.The calculation models show that the yield stress and plastic viscosity have an exponential relationship with the volume fraction of fiber,and have a linear relationship with the ratio of fiber length to diameter.Finally,the whole tailings of Fankou lead-zinc mine are used to verify the calculation model,and the complex correlation coefficients(R^(2))of the fitting equations are all greater than 0.95.