不同配比土石混合体压实特性及颗粒破碎特征研究

为探讨土石混合体填料的压实特性及击实后混合体内部的颗粒破碎程度,在室内进行了不同含石量(P5)的击实试验及颗粒破碎试验。研究结果表明:当P5含量不变时,改变细粒料组成成分及比例对最优含水率的影响较最大干密度更明显;不同级配下土石混合体试样的初始含石量是影响颗粒破碎的关键因素;击实前后颗粒级配曲线所围成的面积可以表征粒径变化程度,粒径发生变化的主要区间为2.5~20mm,且粒径变化大小程度随着粒径减小呈递减小趋势;击实后分形维数与最大干密度和最优含水率有良好的拟合关系,最优含水率对击实后分形维数的影响较最大干密度更为显著;根据分形理论,击实后的分形维数较击实前均增大,且击实前后分形维数的差值与破碎指标都能够在某方面表征混合体的颗粒破碎程度;混合体的相对分形维数随着含石量的增加而增大,即相对分形维数越大,颗粒破碎程度越大。

Properties and interfacial microstructure of cement-based materials with composite micro-grains

Silica fume, fly ash and nano-fiber mineral materials (NR powder) are employed to incorporate into cement-based materials. According to the grain grading mathematical model of cement-based materials, two packing systems, namely, spherical grading system and nano-fiber reinforced system were designed. Properties and interfacial microstructure of the two systems were studied according to secondary interface theory. It was shown that nano-fiber mineral materials can improve the grain grading of the admixture, increase the density of the system, improve the microstructure of the interface and the hardened paste, and enhance the uniformity of cement-based materials mixed with composite micro-grains and greatly increase their wearable rigidity and flexure strength. In this paper, two kinds of interface models, including spherical grain model and nano-fiber reinforced interface model of the cement-based materials mixed with composite micro-grains, were brought forward.