Investigation of Bi-functionalized Clay-Superabsorbent Polymer Nanocomposite for Improved Mechanical and Durability Properties of Cementitious Materials

The impacts of incorporating silane-functionalized halloysite nanoclay (SNC) in sodium polyacrylamide (PA) superabsorbent polymer (SAP) and its reinforcement potential in cementitious materials are carefully investigated. Unlike previous studies, this work uniquely explored the dual functionality of SNC to enhance both the water absorption capacity and mechanical strength of SAPs and, subsequently, its reinforcing effects on cementitious materials. This study comprehensively examines the mechanical and durability characteristics of cement mortar and concrete when a small percentage of SNC/SAP composite is added at 0.2, 0.4, 0.6, and 0.8%. The optimum concentration of SNC/SAP composite in the cement mix was found to significantly improve the hydration of cement, thereby enhancing its mechanical properties and strength by filling the micropores. X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) analyses were carried out to characterize the surface morphology and its influence on cementitious materials. The results indicate that the SNC/SAP cementitious nanocomposite enhances the compressive, flexural, and tensile strengths by up to 54%, 63%, and 67%, respectively, compared to those of conventional mortar specimens at 56 days. Furthermore, shrinkage tests revealed the excellent water-holding capacity of the composite hydrogel, which promoted internal curing and reduced microcrack formation. The findings demonstrate that SNC not only improves the properties of SAP hydrogels but also significantly enhances the mechanical properties and durability of cementitious materials, making it a promising additive for protective cementitious coatings in buildings. This study addresses the critical need for durable, crack-resistant concrete, providing a novel approach to enhancing the longevity and performance of cementitious materials.