Behaviors of Fiber Reinforced Cement Composite Thin Overlay under Restrained Shrinkage

Restrained shrinkage and cracking behaviors of fiber reinforced cement composite (FRCC) overlay containing polyethylene and hooked steel fibers were investigated. The specimens, consisting of thin overlay cast on top of reinforced concrete base, were subjected to drying condition since the time of casting under the condition of high wind, high temperature, and low humidity. Free drying shrinkage and crack widths were monitored for 60 days. The experimental results showed that drying shrinkage was unaffected by the addition of fibers at low dosages. However, fibers reduced both the number of cracks and crack widths on the overlay layers compared to plain mortar overlay, with or without steel mesh reinforcement. Fibers were also effective in reducing the delamination of overlay from the concrete substrate. Polyethylene fibers were found to be more effective than hooked steel fibers in controlling shrinkage cracking.