Machine-made sand (MS) has become a hot topic in construction materials due to the depletion and scarcity of natural river sand. Aggregate micro fines (AMF) of varied contents were included in MS during the manufacturing process. To quantify the filling role of AMF in MS mortars, a physical packing model together with the related mathematical model of fresh mortar was established by considering the water as a void component in fresh mortar mixture. A total 42 MS mortar mixes with different water-cement (W/C) ratios (0.45, 0.5, 0.55, 0.6), different sand-cement (S:C) ratios (1:1, 2:1, 3:1) and different contents of AMF (0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%) were prepared. The effects of AMF on the bulk density and compactness of fresh mortar, flexural and compressive strength, pore structure and microstructure of hardened mortar were investigated. The results show that the changing trend of compactness of fresh mortar is in consistent with the results of the bulk density and mechanical properties of the mortar. The optimal contents of AMF are found to be dependent on the W/C and S:C ratios. Our results show that, when S:C = 2.5:1, the optimal contents of AMF by weight of MS are 5 wt%, 10 wt%, 15 wt%, and 20 wt% for the mixes with the W/C ratios of 0.45, 0.5, 0.55, and 0.6, respectively; when the W/C = 0.5, the optimal AMF contents are 5 wt%, 10 wt%, and 15 wt% for the mixes with the S:C ratios of 1:1, 2:1, and 3:1, respectively. The results of mercury intrusion porosimetry (MIP) and electron backscattered diffraction (EBSD) show that the AMF can modify the pore structure and enhance the interfacial transition zone (ITZ) of mortar.

由于天然河砂的枯竭和稀缺，机械制砂（MS）成为建筑材料中的热门话题。在制造过程中，MS中会包含各种含量的微细粉尘（AMF）。为了量化AMF在MS砂浆中的填充作用，通过将水视为新鲜砂浆混合物中的空隙成分，建立了物理填充模型以及相关的新鲜砂浆数学模型。总共42种MS砂浆混合物，具有不同的水灰比（W / C）（0.45、0.5、0.55、0.6），不同的砂灰比（S：C）（1：1、2：1、3：1）制备不同含量的AMF（0重量％，5重量％，10重量％，15重量％，20重量％，25重量％）。AMF对新鲜砂浆的堆积密度和密实度，抗弯强度和抗压强度的影响，研究了硬化砂浆的孔隙结构和微观结构。结果表明，新鲜砂浆的密实度变化趋势与砂浆的堆积密度和力学性能的结果一致。发现AMF的最佳含量取决于W / C和S∶C比。我们的结果表明，当S：C = 2.5：1时，W / C比为的混合物的最佳AMF含量（按MS重量计）为5 wt％，10 wt％，15 wt％和20 wt％。分别为0.45、0.5、0.55和0.6；当W / C = 0.5时，对于S：C比率分别为1：1、2：1和3：1的混合物，最佳AMF含量分别为5 wt％，10 wt％和15 wt％。