Abstract
The effects of polypropylene fiber and construction operations on the plastic shrinkage cracking of concrete slabs were investigated in this study Statistical methods of experimental design and analysis were employed to derive reliable conclusions. Polypropylene fibers, at relatively low fiber volume fractions, were observed to substantially reduce the total area and maximum crack width of slab surfaces subjected to restrained plastic shrinkage movements. The rate of screeding and the application of finishing operations on fresh concrete surfaces were also critical factors, particularly in plain concrete; slower screeding, followed by finishing (i.e., floating and troweling), led to reduced plastic shrinkage cracking. Longer fibers [0.75 in. (19 mm)] generally performed better than shorter ones [0.50 in.(13 mm)]; however; at certain volume fractions, the effect of fiber length was not statistically significant. Different fiber volume fractions in the range of 0.05 to 0.20 percent performed similarly in reducing plastic shrinkage cracks.