Abstract：In the weak link of fiber reactive powder concrete( RPC) that is tensile stress state,60 sets tension performance experiments of fiber RPC and its corresponding SEM experiments show that( 1) the influence of fiber to the microcosmic mechanism of RPC are not all positive;( 2) crack resistance and toughening effects of fiber are accompanied by the affection of collaboration between aggregates at the same time;( 3) the uncompletely improved interface transition zone have become continuous and straight,affecting the compactness and uniformity of material. The microstructure model of fiber RPC is also proposed based on the analysis of microstructure,crystal structure,phase composition,and the model can be used for the analysis of the microscopic mechanism of fiber RPC. It also provides a theoretical basis for the development and application of efficient and environmentally cement base composite materials.

Keyword：fiber reactive powder concrete(RPC);microscopic mechanism;tensile stress state;phase composition;microstructure model;