Quasi-Static Mechanical Characterization of Lightweight Fly Ash-Based Geopolymer Foams

Abstract

This paper investigates the compressive and flexural behavior of a closed-cell fly ash-based geopolymer foam with a density of 240 kg/m3. The influence of loading speed (0.1, 10, 100, 250 and 500 mm/min) and anisotropy (in-plane and out-of-plane directions) on the compressive mechanical properties at room temperature were investigated. Under compressive loads, the stress-strain curves shows a cellular material typical behavior with three different regions: linear-elastic, plateau and densification region. On the other hand, the three-point bending tests were carried out on both un-notched and notched specimens (for fracture toughness determination). In compression, the foam progressively collapsed with a complete destruction of the successive rows of cells, while in the case of bending it exhibited a brittle behavior without plastic deformation, the fracture occurring by the propagation of a single crack.