pHstimuli‐responsive poly(acrylamide‐co‐sodium alginate) hydrogels prepared by γ‐radiation for improved compressive strength of concrete

Cross‐linking of superabsorbent hydrogels based on poly(acrylamide‐ co ‐sodium alginate) is carried out using 60 Co γ‐radiation. Hydrogels of PAM /NaAlg with 1.5:0.5 and 1.0:1.0 w/v concentrations showed good gel contents of 87 and 66 (%) and swelling degrees in water of 3.7 and 5 (g/g) after 40 min, respectively. The chemical structure of the hydrogel is confirmed by FTIR , XRD , and ESR . The morphology of the hydrogel is observed using scanning electron microscopy. Intramolecular H‐bonding in the hydrogel network is confirmed by TGA and DSC . The pH ‐responsive swelling behavior of ( PAM ‐ co ‐NaAlg) hydrogels is tested in different pH ranges showing higher swelling capacities in basic than in acidic media. This property proposes the use of ( PAM ‐ co ‐NaAlg) hydrogel as internal curing agent for concrete. The hydrogel is examined with cement weight ratios of (0.1–0.5) wt%. The study shows that cement with ( PAM ‐ co ‐NaAlg) hydrogel improves the compressive strength of cement at 0.1 and 0.2 wt%.