Abstract
This study experimentally investigated the autogenous healing performances of cementitious materials incorporating superabsorbent polymers (SAPs) after exposure to eight cycles of wet/dry conditions. In each cycle, cracked cement paste specimens with different SAP dosages were exposed to wet conditions for 1 h, during which capillary water absorption tests were conducted, and then exposed to dry conditions for 47 h. The test results reveal that the initial sorptivity values of the reference, 0.5% SAP, 1.0% SAP, and 1.5% SAP specimens after one cycle were decreased by 22.9%, 36.8%, 42.8%, and 46.3%, respectively, after eight cycles. X-ray micro-computed tomography analysis showed that the crack volume percentages filled with healing products were 1.1%, 1.6%, 2.2%, and 2.9% in the reference, 0.5% SAP, 1.0% SAP, and 1.5% SAP specimens, respectively. As the cycling was repeated, the reduction ratio of the initial sorptivity and the quantity of healing products were increased with increases in SAP dosage. Furthermore, more healing products were distributed near SAP voids than in other sections in the specimens. This study demonstrates that the incorporation of SAPs in cementitious materials can enhance the autogenous healing performances of materials exposed to cyclic wet/dry conditions.
Highlights
Superabsorbent polymers (SAPs) are hydrogel materials capable of absorbing and retaining moisture by osmotic pressure that can swell to several hundred times their own dry weight
As this study focuses on analyzing the autogenous healing performance of cementitious materials by observing the water absorption, only the initial sorptivity, which is closely related to crack healing as described above, was evaluated in the test
This study experimentally analyzed the effect of internal curing by superabsorbent polymers (SAPs) on the autogenous healing performances of cementitious materials exposed to cyclic wet/dry conditions
Summary
Superabsorbent polymers (SAPs) are hydrogel materials capable of absorbing and retaining moisture by osmotic pressure that can swell to several hundred times their own dry weight. This water absorption capacity enables the use of SAPs as internal curing agents to mitigate the autogenous and drying shrinkage of concrete, which is primarily related to moisture loss [1]. The autogenous healing of hardening cementitious materials, which is the outcome of further hydration of unhydrated cement particles [9,10], can be promoted by the internal curing effects of SAPs, when the materials are exposed to the atmosphere.
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