Gangue geopolymer to strength fire resistance of intumescent waterborne coating

Based on its characteristics, gangue, which contains stabilized silica and aluminum oxide, is suitable for preparing high-temperature-resistant materials. Geopolymer (GP) derived from gangue (CG) is characterized by a three-dimensional mesh structure and used as a filler in water-based intumescent fireproofing coatings, which improves the fire performance of the coatings and, to a certain extent, also alleviates the environmental problems caused by the large number of outputs of CG, and plays the role of turning waste into treasure. Experimental tests showed that the fireproof coating with 4% GP showed excellent high-temperature fire retardant properties, and the maximum expansion factor was 16.3, and the minimum backsheet temperature was 256.4°C by simulating the large-board method. The addition of GP with three-dimensional mesh structure enhances the densification of the coating and delays the burning time of the coating, which is delayed by 10 s compared with that of the coating without GP. In addition, it also reduces the generation of CO, has less heat release and better thermal stability, which can be confirmed by the cone calorimeter test and thermogravimetric (TG) analysis. The limiting oxygen index (LOI) of the coating with the addition of 4% GP is 60.2%, which is much higher than that of the flame retardant standard (27%). The results of these tests show the coating’s excellent ability to form a protective barrier, limit heat transfer and delay the decomposition process.