Influences of aggregate micro fines on the packing of fresh mortar and the performances of mortar

Abstract

Water was regarded as the particle that its size is the minimum. According to the size of particle, the particles in the fresh mortar were divided into three grading: water, powder, and sand. The physical model of fresh mortar were established through the two-stage filling of particles, that is to say, the paste fills the voids of sand particles, water fills the voids of the powder particles in the remainder paste, and the remainder water is called as the surplus water. To calculate the remainder water in fresh mortar, the mathematical model of the packing was established to quantitatively characterize the physical filling effect of AMF in fresh mortar. On this basis, the manufactured fine aggregate (MFA) mortars with different water-to-cement (W/C) ratio (0.45, 0.50, 0.60, and 0.65) and different sand-to-cement (S/C) ratio (3:1, 2:1, and 1:1) were taken as the research object, and the influences of the AMF on the surplus water, bulk density, and mechanical property were studied when its content is respectively 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, and 30 wt% in MFA. The results show: the physical filling effect of AMF in fresh mortar can be better characterized with the volume of surplus water in fresh mortar, and the influence of the AMF on the packing of fresh mortar is better consistent with the bulk density of fresh mortar and the mechanical property of hardened mortar. This is the good references for the packing characterization of fresh mortar and the content determination of AMF in MFA.