Porous structure optimisation of flash-calcined metakaolin/fly ash geopolymer foam concrete

Gabriel Samson, Martin Cyr
2017 European Journal of Environmental and Civil Engineering  
This study reports the production and characterization of geopolymer foam concrete (GFC). This material is foreseen for use as a self-bearing insulation material. In order to identify an optimal paste composition, eight mixtures were made and are presented in a ternary diagram (dry extract of alkaline solution, flash-calcined metakaolin (MK) and fly ash (FA)). The characterization of these pastes (initial setting time (IST), shrinkage and compressive strength) indicated an optimal composition
more » ... timal composition corresponding to 25% of activator, 62.5% of MK and 12.5% of FA. The GFCs were then produced by inserting variable amounts of H2O2 (1, 1.5 and 2%) into the geopolymer paste. The fresh GFC porous structure was stabilized with surfactant. The GFCs produced had low densities (225 < ρ < 506 kg/m 3 ) associated with low thermal conductivities (0.07 < λ < 0.12 W/(m.K)) and acceptable compressive strength (0.5 < Rc < 1.85 MPa, for samples cured at 20°C). A significant influence of the surfactant content on the porous structure was demonstrated. The lower surfactant content led to a porous structure made of larger bubbles separated by wider matrix walls promoting GFC compressive strength.
doi:10.1080/19648189.2017.1304285 fatcat:rdnmw4sy6bddjhkqfmzhh5hfzi