Influence of Barchip fiber length on early-age behavior and cracking resistance of concrete internally cured with super absorbent polymers

High performance concrete (HPC) has been applied in practical engineering for a wide range owing to its superior performances, including low permeability, high strength, high modulus, and other superior performance. However, with the high internal temperature and self-desiccation that induced by the low water-to-binder (wpb) ratio, HPC suffers high autogenous shrinkage, which leads to the premature cracking of HPC after peak stress at early age. For the purpose of increasing the cracking resistance of concrete effectively, Barchip fibers and the internal curing materials are used to improve the early-age properties of concrete. Although researches on the cracking resistance of HPC reinforced with different contents of Barchip fiber or internally cured with different kinds of internal curing materials have been conducted, studies on the effect of Barchip fiber length on the cracking resistance of internally cured HPC (ICHPC) with super absorbent polymers (SAPs) at early age are rather lacking. In present research, the effect of length of Barchip fibers (0, 42, 54, and 60 mm) on the early-age cracking resistance of ICHPC under the adiabatic condition was studied by Temperature Stress Test Machine. Results of the experimental research and related analysis indicated that (1) the splitting tensile strength and compressive strength of HPC increased as the Barchip fibers were applied; (2) the use of SAPs reduced autogenous shrinkage, restrained tensile stress rate, and tensile creep behavior, and increased temperature drop and the cracking resistance of HPC at early age: (3) the autogenous shrinkage decreased and the temperature drop, cracking age, cracking stress of ICHPC increased as the Barchip fiber length increased; (4) the tensile creep behavior of ICHPC increased as the Barchip fibers were applied, and decreased as the Barchip fiber length increased; (5) the cracking resistance of ICHPC increased first and then decreased as the Barchip fiber length increased, as obtained from the integrated criterion; (6) the poor dispersion of Barchip fibers may result in the decrease of the early age behavior and cracking resistance of ICHPC when the fiber length exceeded 54 mm. (C) 2019 Elsevier Ltd. All rights reserved.