Early-Age Cracking Resistance of Fiber-Reinforced Expansive Self-Consolidating Concrete

摘要

To improve the early-age cracking resistance of self-consolidating concrete (SCC), this paper investigated the effects of an expansive agent (EA), fibers, and the interaction between EA and fibers on the cracking behavior of restrained SCC caused by plastic shrinkage based on the slab test. Twenty-one types of samples were prepared, including one control group, two EA contents (6 and 8% of the mass fractions of cementitious materials), three steel fiber contents (0.25, 0.50, and 0.75% by volume), three polypropylene fiber contents (0.05, 0.10, and 0.15% by volume), three hybrid fiber contents, and nine combinations of EA (8% of the mass fraction of cementitious materials) and fibers. The initial cracking time and propagation of cracks over time were both observed. Test results indicate that an increase of EA dosage presents no significant improvement on early-age cracking resistance capability. Compared with steel fiber (SF), polypropylene fiber (PP) with equivalent fiber factors was particularly effective in reducing the nominal total crack area. In general, crack reduction factors of fiber-reinforced expansive self-consolidating concrete (FRESCC) are 70% greater than that of SCC containing fiber only. It indicates that the combination of EA and fibers enable SCC to present better early-age cracking resistance.