Facile preparation of slag or fly ash geopolymer composite coatings with flame resistance

A major concern in preparing flame retardant coating today is to continue to improve its sustainable and ecological performance, and geopolymerization is converting industrial solid wastes into chemically durable cement-like binders with excellent thermal stability and non-combustibility. Therefore, two series of novel coatings were facilely prepared via sol-gel method, which contained floating beads of fly ash and granulated blast-furnace slag, using Na2SiO3 as the alkali-activator, accompanied with organic modifier and film-forming agent respectively. The results showed that the geopolymeric coating transformed into siliceous layer for blocking transfer of heat and mass, leading to the decreases in the value of heat release rate (HRR) and fire growth index (FGI), and an increased fire performance index (FPI). However, the flame retardant effect of slag-based coating mainly depended on the dehydration derived from C-S-H(l) and amorphous (HO)(3-)Si-O-Si . It identified that an appropriate dosage (25 wt%) of fly ash or slag was crucial to obtain excellent flame retarding efficiency. (C) 2019 Elsevier Ltd. All rights reserved.