Comparative study between natural and PVA fibers to reduce plastic shrinkage cracking in cement-based composite

• Testing parameters cover a wide range of fiber properties including: type, length, volume, geometry and aspect ratio (l/d).
• The effectiveness of fibers was focused on reducing the number of cracks and total crack area.
• The natural fibers were effective in controlling restrained plastic shrinkage cracking.
• Was demonstrated the fiber length did not significantly influence cracking behavior.

The main objective of this study is to control restrained plastic shrinkage cracking through the addition of natural and PVA fibers in a cement-based composite. Two types of natural fibers (flax and agave lechuguilla) as well as synthetic fibers (PVA) were investigated at volume fractions of 0.1% and 0.7%. 38 prismatic mortar specimens were freshly cast on top of a grooved and hard concrete substrate, providing a bottom restraint; this resulted in cracking in the freshly placed overlay, which was detected as a function of time. The effectiveness of the fibers was evaluated by considering reducing the number of cracks and total crack area under these conditions. The results obtained show that both natural fibers were effective in controlling restrained plastic shrinkage cracking like the commercially available PVA fibers; the total crack areas were also reduced by at least 93% compared with plain mortar specimens.