Influence of polypropylene fiber and expansive agent on microstructure of concrete

The influence of polypropylene fiber, expansive agent and combination on microstructures of concrete was studied. Internal structures of polypropylene fiber concrete, expansive concrete and polypropylene fiber-reinforced expansive concrete were studied by using permeation depth, chloride ion permeability of concrete, AC Impedance Spectrum and MIP tests. SEM was used to analyze interfacial structures of fiber, the matrix of concrete. The results show that fiber may strengthen the effects of filling with pores and diminishing pore size by expansive agent, and expansive agent increases interface bonding between fiber and the matrix of concrete. Which polypropylene fiber and expansive agent are compounded, it leads to the decrease of porosity and pore size, and improves microstructure of concrete.