AbstractA series of laboratory tests including flow consistency, viscosity, one-dimensional compression, and permeability were conducted on the fiber-reinforced cemented waste slurries obtained from a construction site to evaluate the fiber efficiency on the flow behaviors and compressibility-permeability properties. Results indicated that the fiber efficiency did not increase with increasing fiber length in this study because the waste slurry was composed of high montmorillonite and illite contents in this study. Fiber had a limited effect on the flow behaviors of the slurry mixture because the slurry reinforced by short fibers exhibited dispersive soil particles and fibers in the suspension. Longer fibers can bridge the soil particles and contribute to an aggregated fiber–soil matrix. A perfect fiber network with soil particles could be obtained at fiber content of 0.8%, where a well-fitted trendline can be obtained between slump flow and viscosity with high fiber efficiency. The cement content was found to dominate the compressibility of soil at higher water content. Fiber lengths in the range from 3 to 8 mm exhibited effective fiber reinforcement in terms of hydraulic conductivity. It is recommended to reinforce the waste slurry at fiber content of 0.8% with the optimal fiber length between 6 and 8 mm for the cemented waste slurry in this study.