Cast-in-Place Cellulose Fiber-Reinforced Concrete: Shrinkage, Dispersion, Rheology

摘要

Cellulose fibers are inexpensive reinforcement for cement-based materials. Traditionally, they have been used to replace asbestos in fiber-reinforced cement board. Because of their low cost and demonstrated reinforcing ability, cellulose fibers are investigated as reinforcement for cast-in-place concrete. This study characterizes the behavior of cellulose fiber-reinforced paste and mortar and investigates rheological, dispersion, and mechanical properties of the materials. Restrained ring shrinkage tests are performed on mortar and paste to evaluate the potential of the fibers to control shrinkage cracking at a range of fiber volumes. Fiber dispersion is analyzed and compared with shrinkage cracking control in paste. A rheological parameter, such as yield stress or viscosity is investigated for predicting fiber dispersion. At low volumes, fibers are found to reduce significantly the width of restrained ring shrinkage cracks in mortar. At higher fiber volumes, multiple cracking is observed in mortar. In paste rings, fiber dispersion and performance are positively correlated. Yield stress is shown to be a poor indicator of fiber dispersion.