Research on Alkali-Activated, Spinelized Kaolin Cementitious Composite Materials

This study prepared alkali-activated cementitious composites using high-whiteness kaolin, sodium water glass, and NaOH as the main raw materials. Multiple methods, including FE-SEM, XRD, whiteness/light transmittance tests, shrinkage rate measurements, DSC-TG, flexural strength testing, and hydrolysis resistance testing, were used to investigate the effects of curing temperature and time on material properties. The optimal parameters were determined as kaolin calcined at 1100 °C, activator modulus 1.25, calcined kaolin-to-activator ratio 1:1, and 2.5% deionized water added for molding. The optimal sample achieved a flexural strength of 23.81 MPa, with the bonding strength to porcelain 60.17 times that of gypsum and 1.90 times that of kaolin-bonded materials. Curing below 100 °C slowed polymerization, while temperatures exceeding 100 °C accelerated it, with violent reaction at 120 °C. Curing beyond 10 h reduced flexural strength. A large number of cage-like, 'zeolite-like' structures formed, closely relating to material properties. This study provides references for ceramic restoration materials.