Abstract: In order to prepare ultrahigh strength cement-based materials that was ecological and more suitable for engineering applications, limestone powder was used to replace the cement and silica fume in the ultrahigh strength cement-based materials, and the influence of limestone powder on the rheological characteristics of ultrahigh strength cement-based materials was studied by micro slump meter and rheometer. The results show that when limestone powder replaces part of the cement and silica fume, the ultrahigh strength cement-based materials appears shear thickening, and the yield stress and plastic viscosity are reduced, indicating that the mixing of limestone powder can improve the segregation and bleeding of ultrahigh strength cement-based materials during pumping, and can improve the filling capacity of ultrahigh strength cement-based materials during pouring. Compared with limestone powder replacing cement, when limestone powder replaces silica fume, the shear thickening degree and fluidity of ultra-high strength cement-based materials are significantly increased and the yield stress and plastic viscosity are significantly reduced, indicating that replacing silica fume can greatly improve the construction performance of ultrahigh strength cement-based materials. The fluidity, yield stress, and plastic viscosity of ultrahigh strength cement-based materials meet the quadratic polynomial function relationship. When the replacement amount of limestone powder for cement should not exceed 17% and the replacement amount of silica fume should be 50%, the rheological properties of ultrahigh strength cement-based materials are greatly improved, and the 28-day compressive strength increases by 15.6%.

Key words: highway engineering; limestone powder; rheology; ultrahigh strength cement-based materials; cement; silica fume

摘要： 为制备更适宜工程应用的超高强水泥基材料，利用石灰石粉分别取代超高强水泥基材料中的水泥和硅灰用量，通过微型坍落度仪和流变仪研究了石灰石粉对超高强水泥基材料流变特性的影响。研究结果表明：当石灰石粉取代部分水泥和硅灰时，超高强水泥基材料出现剪切增稠，屈服应力与塑性黏度降低，说明掺入石灰石粉可改善超高强水泥基材料在泵送过程中出现的离析、泌水等现象，提高超高强水泥基材料在浇筑时的充填能力；相比于石灰石粉取代水泥，当石灰石粉取代硅灰时，超高强水泥基材料剪切增稠程度和流动度明显增大、屈服应力及塑性黏度显著降低，表明取代硅灰时对超高强水泥基材料的施工性能有较大的改善作用；超高强水泥基材料的流动度与屈服应力、塑性黏度满足二次多项式函数关系，且石灰石粉取代水泥量不宜超过17%，硅灰取代量宜为50%，此时超高强水泥基材料流变性能得到较大改善，28 d抗压强度增加15.6%。

关键词: 道路工程；石灰石粉；流变；超高强水泥基材料；水泥；硅灰