Influence of reswollen superabsorbent polymers on the corrosion behavior of steel fibers in cracked mortars exposed to NaCl solutions

Abstract

Superabsorbent polymers (SAPs) can decrease the water penetration depth and crack width in cracked cementitious materials. This suggests that SAPs may inhibit the corrosion behavior of steel fibers in cracks. In this paper, the effects of SAPs on the mechanical properties and crack pattern of mortars were respectively studied with a uniaxial compression test and a 3-point bending test. The 3D morphology of the reswollen SAPs and their influence on the water flow rate in the cracked mortars were investigated with an X-ray computed microtomography and a water flow test, respectively. Additionally, the corrosion behavior of steel fibers in the cracked mortars with and without SAPs was explored with electrochemical techniques. The results reveal that SAPs can mitigate the rapid stress-drop of mortars during failure, resulting in a reduction in the crack width on the mortar surface. The volume of the reswollen SAPs in a crack decreases when the NaCl concentration is above 0.1 mol/L, while SAPs can partially block the SAPs void and decrease the flow rate of NaCl solutions in the cracked mortars. Furthermore, in NaCl solutions (0.1 and 0.5 mol/L), SAPs can reduce the probability and rate of the corrosion of steel fibers in the cracked mortars. This is advantageous for the durability of the smart cementitious materials containing SAPs.