Performance of cementitious mortars containing hydrogel–nanoclay hybrid nanocomposite

Abstract

Abstract Cement-based composites comprise a binder matrix with or without aggregates. Hydration of cement is an exothermic reaction that releases considerable quantities of heat, causes drying shrinkage, and results in cracks that can compromise the performance of the structure. Hydrogels can help mitigate such cracking as their hydrophilic characteristics and 3D crosslinked structure enable them to absorb and directly release water into the cement matrix over time. The aim of this study is to synthesize and analyze the effect of adding hybrid nanocomposite hydrogels with different concentrations (0, 10, and 20% w/v) of Cloisite-Na+ nanoclay in their fresh and hardened cement mortar states. The hydrogels were synthesized via free radical polymerization, and four cementitious mortar samples (M, M0, M10, and M20), were prepared with 1:2.16, 0.40 water/cement and 0.50% presoaked hydrogel (wt./wtcement) ratios. The results demonstrated that the density of all the mortars in the fresh state was ~ 2.16 ± 0.01 g.cm− 3, but a decreasing trend was observed that could attributed to the increase of air incorporation into the mortar. At 28 days, the results indicated that the hydrogel with 20% Cloisite-Na+ was the most efficient, causing a reduction of ~ 4.41% in water absorption by the mortar. For all the three curing conditions considered, all mortars demonstrated considerable shrinkage over time. However, the controlled curing indicated that M20 mortars demonstrated 30.5% less shrinkage compared to the control sample. Thus, the results indicate that the mortars containing hydrogel demonstrate satisfactory behavior in both the fresh and hardened state, highlighting its efficiency as a curing agent.