Mitigation of Early-Age Cracking of Concrete Based on a New Gel-Type Superabsorbent Polymer

Shrinkage cracking of concrete at an early age has notable and adverse effects on the durability and long-term performance of the material because it damages surface integrity or undermines overall uniformity of concrete. In order to mitigate early-age concrete shrinkage cracking, a new gel-type superabsorbent polymer (SAP) has been developed as an internal curing agent (ICA). This paper investigates the effects of the introduced gel-type ICA dosage and curing conditions on early-age cracking mitigation of concrete. It is found that the cracking area of concrete is greatly reduced when up to 41 kg/m(3) gel ICA is used in concrete with water: cement ratio (w:c) of 0.5, and the internal relative humidity (IRH) of concrete at 7 days can be maintained at 92% or above. The gel-type ICA also is more effective in delaying initial cracking time and lowering the decreasing rate of IRH. It is believed that the superiority of this newly introduced ICA lies not only in its uniform dispersion in concrete but also in its molecular network structures, which contribute to maintaining moisture balance in the near-surface layer of concrete. This new gel-type ICA provides a new alternative way to control early-age cracking of modern concrete and it has a promising future in concrete construction, especially in windy, drying, and high-temperature areas. (C) 2017 American Society of Civil Engineers.