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Time-dependent rheological and mechanical properties of silica fume modified cemented tailings backfill in low temperature environment
Cement and Concrete Composites ( IF 10.8 ) Pub Date : 2020-09-02 , DOI: 10.1016/j.cemconcomp.2020.103804
Wenbin Xu , Yalun Zhang , Xiaohua Zuo , Ming Hong

The objectives of this study are to examine the rheological and mechanical property of fresh CTB incorporating silica fume (SF) at low temperature and in an effort to assess the applicability of using SF as a partial cement replacement. The cement replacement level was set at 0% (control), 2.5%, 5.0% and 10.0% by weight. Furthermore, the effect of curing temperature (−12, −1, 6, and 20 °C) on time-dependent rheological behavior of fresh CTB within 240 min was also examined and analyzed. The results indicate that the time-dependent rheological behavior of fresh CTB is significantly affected by curing age and silica fume replacement. Both the yield stress and viscosity increase steadily as curing time elapses, and the CTB sample cured of 20 °C has the highest yield stress and viscosity, while that cured of −1 °C presents the lowest values for all the curing periods. However, the CTB samples cured of −12 °C show a slight decrease in viscosity and yield stress until 40 min, then follow by an instant increase due to water frozen. In addition, the yield stress of fresh CTB is elevated by mixing of silica fume, but the viscosity decreases. The uniaxial compressive strength of CTB at low temperature (−1 °C) is enhanced with increasing of silica fume, and the CTB samples with 5.0% silica fume replacement for cement exhibit the highest compressive strength among all CTB mixtures regardless of curing age. The CTB samples with 5% silica fume present refiner pore structure than that with 0% and 10.0% replacement.



中文翻译:

硅粉改性水泥尾矿回填物在低温环境下的时变流变和力学性能

这项研究的目的是在低温下检查掺入硅粉(SF)的新鲜CTB的流变和机械性能,并评估使用SF作为部分水泥替代品的适用性。水泥替代水平设定为0重量%(对照),2.5重量%,5.0重量%和10.0重量%。此外,还研究并分析了固化温度(-12,-1、6和20°C)对新鲜CTB在240分钟内随时间变化的流变行为的影响。结果表明,新鲜的CTB随时间变化的流变行为受固化年龄和硅粉替代的影响很大。随着固化时间的延长,屈服应力和粘度都稳定增加,并且在20°C固化的CTB样品具有最高的屈服应力和粘度,而在-1°C下固化的温度在所有固化期间均呈现最低值。但是,在-12°C下固化的CTB样品在40分钟前粘度和屈服应力略有下降,然后由于水冻结而立即增加。另外,通过混合硅粉来提高新鲜CTB的屈服应力,但是粘度降低。CTB在低温(-1°C)下的单轴抗压强度会随着硅灰的增加而增强,并且在不考虑固化年龄的情况下,以5.0%硅灰替代水泥的CTB样品在所有CTB混合物中均表现出最高的抗压强度。含5%硅粉的CTB样品比含0%和10.0%替代品的CTB样品具有更细的孔结构。然后由于水冻结而立即增加。另外,通过混合硅粉来提高新鲜CTB的屈服应力,但是粘度降低。CTB在低温(-1°C)下的单轴抗压强度会随着硅灰的增加而增强,并且在不考虑固化年龄的情况下,以5.0%硅灰替代水泥的CTB样品在所有CTB混合物中均表现出最高的抗压强度。含5%硅粉的CTB样品比含0%和10.0%替代品的CTB样品具有更细的孔结构。然后由于水冻结而立即增加。另外,通过混合硅粉来提高新鲜CTB的屈服应力,但是粘度降低。CTB在低温(-1°C)下的单轴抗压强度会随着硅灰的增加而增强,并且在不考虑固化年龄的情况下,以5.0%硅灰替代水泥的CTB样品在所有CTB混合物中均表现出最高的抗压强度。含5%硅粉的CTB样品比含0%和10.0%替代品的CTB样品具有更细的孔结构。水泥的0%硅粉替代品在所有CTB混合物中均显示出最高的抗压强度,而与固化年龄无关。含5%硅粉的CTB样品比含0%和10.0%替代品的CTB样品具有更细的孔结构。水泥的0%硅粉替代品在所有CTB混合物中均显示出最高的抗压强度,而与固化年龄无关。含5%硅粉的CTB样品比含0%和10.0%替代品的CTB样品具有更细的孔结构。

更新日期:2020-09-08
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