Salt-Scaling Resistance of SAP-Modified Concrete Under Freeze–Thaw Cycles

Abstract

AbstractConcrete structures can be subjected to a range of deteriorating processes due to environmental exposure. When subjected to freeze–thaw cycles, the concrete can experience scaling of the surface layer and internal damage that can further lead to cracking and open the path to other deleterious agents. During winter times, the use of de-icing salts is a very common practice to aid in the cleaning and clearance of roads, bridges and tunnels which increases the effects of scaling. Lately, a lot of research has been developed on the use of superabsorbent polymers (SAPs) to increase the durability of concrete structures by means of internal curing, self-sealing and self-healing. The SAP-modified concrete presents a higher resistance to salt-scaling when compared to concrete mixtures without SAPs. In this paper, the scaling resistance of four concrete compositions with and without superabsorbent polymers is studied. One commercial SAP applied to mitigate the autogenous shrinkage and two “in-house” developed SAPs are used. Cylindrical specimens were exposed to 28 freeze–thaw cycles with a 3% NaCl solution. Two of the SAP containing-mixtures showed a reduction of 49% (commercial SAP) and 54% (“in-house” SAP) in salt-scaling in comparison with the reference mixture. On the other hand, another “in-house” developed SAP induced an increase in scaling. The water kinetics of the SAPs was found to play a major role in the performance of the mixtures regarding the scaling resistance.KeywordsSuperabsorbent polymersFreeze–thawSalt-scaling resistance