**6. Conclusions and Future Works**

Geopolymer material with a low calcium content holds great potential for future ceramic applications because geopolymers have superior characteristics to OPC counterparts and have various performance-related qualities. Even though the characteristics of geopolymer have been thoroughly explored in the literature, there are still certain elements that require additional investigation. Furthermore, it is evident from this brief analysis that addition of zirconia into kaolin geopolymer applications still has a great deal of room for research and improvement. Zirconia-reinforced geopolymer matrices produce materials with enhanced compressive, fracture toughness, crack resistance, and thermal stability, relative to the unreinforced matrix. In conclusion, the essential formulation parameters for geopolymers were assembled and compared based on chemical composition, thermal processing, and consequent mechanical properties. Based on the facts reviewed, it is obvious that additional research must be conducted to optimise formulas for the development of zirconia-reinforced geopolymers with improved characteristics. Several conclusions can be drawn from a review of the existing literature on the properties of geopolymer materials in ceramic industry:


The significant of this review to the ceramic industry is to produce ceramic geopolymers with high compressive strength at optimal sintering temperature of kaolin. The potential of addition of zirconia may enhance the properties of kaolin geopolymers to reduce energy consumption and increase residual compressive strength without affected the growth of ceramics grains during sintering.

**Author Contributions:** Conceptualization, N.A.M.M., M.M.A.B.A., R.A.R., M.N. and R.P.J.; data curation, N.A.M.M., M.M.A.B.A., S.Z.A.R., R.A.R. and A.S.; formal analysis N.A.M.M., R.A.R., R.P.J., A.S. and R.M.; investigation, N.A.M.M., M.M.A.B.A., M.F.G., M.N. and A.S.; methodology, M.M.A.B.A., M.F.G. and R.A.R.; project administration; N.A.M.M., I.H.A. and R.M., validation, M.M.A.B.A., R.A.R., I.H.A. and S.Z.A.R.; writing—review and editing, N.A.M.M., M.M.A.B.A., R.A.R., S.Z.A.R. and R.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by the Center of Excellence Geopolymer and Green Technology (CEGeoGTECH) UniMAP and Faculty of Technology Chemical Engineering, UniMAP. The authors appreciated the support from Research Materials Funding (RESMATE-9001-00629) and Universiti Malaysia Pahang under research grant number PDU213219.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors acknowledge the Center of Excellence Geopolymer and Green Technology, University Malaysia Perlis for the contribution. Special thanks to those who contributed to this project directly or indirectly.

**Conflicts of Interest:** The authors declare no conflict of interest.
