A REVIEW ON FIRE-RESISTANCE PERFORMANCE OF GEOPOLYMER COATINGS

Geopolymer is a promising fire-resistant coating material due to its admirable mechanical properties and thermal performance. This paper reviews the thermal performance of geopolymer-coating subjected to elevated temperature. Geopolymer coatings, geopolymer mortar, and concrete are with the similar fire- resistance performance, but with some differences. Size effects would affect the geopolymer coating in the ways of thermal expansion and shrinkage. The thermal expansion and mass loss of geopolymer coating are larger than that of geopolymer mortar and concrete. Chemical instability leads to weak volume stability and mechanical strength, whereas high chemical stability and microstructural performance may not result in positive volume stability and strength behaviors. The factors of Si/Al ratio, Al/Na ratio, water content, precursor type, alkali cation type, and curing conditions etc. are involved in mix ratio design which basically determines the performance of geopolymers. To improve the mechanical properties and fire-resistance capacity of geopolymers, slag, fibers, lightweight aggregates, inorganic fillers, and nano material would be considered in further studies. Furthermore, a further study is advised to be placed in the relationships between the microstructure changes, the macroscopic properties, and the reaction mechanism of geopolymer at high temperature still.