Developing a Polypropylene Fabric, Silica Fume, and Redispersible Emulsion Powder Cementitious Composite for Dynamic Water Environment

In the dynamic water environment, grouting requires a material with higher strength and anti-washout performance to prevent groundwater inrush. This study aims to develop a dynamic water slurry by mixing polypropylene fiber (PP fiber), silica fume (SF) and the polymer material of redispersible emulsion powder (REP) to the Portland cement. Towards this aim, a series of tests, including strength, gel time, bleeding rate, fluidity, and anti-washout, were conducted to evaluate the effects of SF, PP fiber, and REP on the slurry properties. The test results show that: (1) SF displays significant effects on strength, gel time, fluidity, and bleeding rate of cement slurry. Differently, PP fiber mainly affects the stress–strain behavior of the slurry and can improve the ductility significantly. (2) By mixing SF and fiber simultaneously, the slurry strength can increase by about 30%, and its strain can extend by more than 70%. Meanwhile, the composite slurry possesses great anti-washout properties at a low flow velocity (v ≤ 0.4 m/s), and the grouting retention rate (GRR) can reach up to 98.7%. However, the GRR decreases to a maximum value of 31.3% when v = 0.6 m/s. (3) By mixing the REP into the fiber-SF composite slurry, the GRR can further increase, reaching more than 60% even when v = 0.6 m/s. As a result, the developed fiber-SF cementitious composite slurry, which when mixed with REP, presents a favorable performance in the dynamic water environment.