Effect of Barchip fiber on stress relaxation and cracking potential of concrete internally cured with super absorbent polymers

Abstract

High-strength concrete (HSC) that has shown the outstanding performance is extensively utilized in construction. HSC usually suffers the high autogenous shrinkage when the water-to-cement (w/c) ratio is low. Internal curing (IC) is developed as reservoir in concrete to reduce HSC shrinkage at early age by introducing additional water. Meanwhile, Barchip fibers have been already utilized to improve material properties of HSC. Investigations on the effect of the proportion of Barchip fibers (0%, 0.3%, 0.6%, and 0.9% by volume fraction of concrete) on early-age stress relaxation of concrete internally cured with super absorbent polymers (SAPs) were conducted by restrained ring test. Results obtained from the test were as follows: (1) the free shrinkage in concrete deceased with the increase of the proportion of Barchip fibers; (2) the strain in steel ring decreased when the proportion of Barchip fibers increased; (3) the residual stress in concrete decreased with the increase of the proportion of Barchip fibers; (4) increasing the proportion of Barchip fibers caused the decrease of stress rate; (5) the relaxed stress increased with increase of Barchip fibers proportion; (6) when the proportion of Barchip fibers increased, the time to cracking of concrete was delayed, and the cracking potential of concrete decreased significantly; (7) SAPs utilized in IC improved the performance of concrete reinforced with Barchip fibers significantly.