Failure mechanism of geopolymer composite lightweight sandwich panel under flexural and edgewise compressive loads

Abstract

This paper proposes a new lightweight sandwich panel manufactured with Fiber-Reinforced Geopolymer Composite (FRGC) skin layers and PUR foam core for prefabricated buildings. The failure mechanisms of the developed sandwich panel are investigated under flexural bending and edgewise compressive loading to validate the performance of the developed panel. Digital Image Correlation (DIC) technique is used to obtain the deformation and strain during the tests. Two typical failure mechanisms, i.e. shear failure of the core and tensile failure of the skin layers of the one-way sandwich panel under flexural loading are studied by conducting quasi-static three-point bending tests. The influence of the core thickness-to-span ratio of the sandwich panel on shear failure of the core is studied. The test results show that the failure mode transforms from the shear failure of the PUR foam core to delamination between the FRGC skin and PUR foam core, when the thickness-to-span ratio increases from 0.1 to 0.3. The influence of skin thickness-to-span ratio on the skin tensile failure is also studied. Analytical models for the shear failure of the core and the tensile failure of the skin layer are proposed. Furthermore, the failure mechanism of the developed sandwich panel with different thickness-to-length ratios under edgewise compressive loading is studied. It is found that the failure mode changes from the material failure of the FRGC skin to the global buckling when the thickness-to-length ratio reduces from 0.90 to 0.30. Analytical models for predicting the critical failure load under edgewise compressive loading are also proposed.