Flame resistance of geopolymer foam coatings for the fire protection of steel
Johan Sarazin, Catherine Davy, Serge Bourbigot, Grégory Tricot, Jérôme Hosdez, David Lambertin, Gaëlle Fontaine
Abstract
This research investigates the fire resistance of novel geopolymer (GP) foams, based on alkali-activated metakaolin and silica fume (SF). Fresh GP foams are applied as coatings on steel plates. After one week curing, the foams are subjected to a flame burn-through test. Changes in their physico-chemical properties are characterized before and after fire test, mainly with XRD , quantitative MAS NMR, electron probe micro-analysis, quantitative X ray micro-computed tomography and heat conductivity . Results show that GP foams are excellent thermal barriers, providing up to 251 °C less than for uncoated steel plate. Their porosity ranges between 25 and 81%, for typical pore sizes d 50 from 0.5 to 3.0 mm 29 Si MAS NMR shows that the proportion of GP cement only decreases from 60-68% to 53–58% after fire. SF expands and creates small pores in the coating, which is favorable to decrease heat conductivity by a factor of 2 whatever the foam. • Novel GP foams based on MK + SF are formulated and characterized for fire resistance. • H 2 O 2 and CTABr foam stabilizing agent provide a controlled porosity of 81%. • GP foams provide superior fire protection to steel in a burn-through scenario. • The amount of GP cement only decreases from 60-68% to 53–58% after fire test. • Due to SF expansion, heat conductivity of foams is reduced by a factor of 2.