Freeze-thaw effect on performance degradation of recycled glulam from structural members after cyclic loading

Abstract

To achieve sustainable production with recycled glulam from after-service structural members, the physical and mechanical properties of the recycled glulam under different numbers of freeze-thaw cycles (60, 120, 180 times) were investigated. The results showed that the freeze-thaw cycle treatment had a serious damaging effect on the glue layer, rather than the laminates of the specimens, which showed the tackless phenomenon. The physical properties (color change, mass and dimensional variation) of the specimens changed most significantly after the first freeze-thaw cycles (60 cycles), and then showed slow growth. As the number of freeze-thaw cycles on the specimens increased, the strength, especially the shear strength of the specimens showed a significantly decreasing trend (45% for compressive strength and 100% for shear strength after 180 cycles), whilst the ductility shows an increasing trend. A strength prediction model of the recycled glulam under freeze-thaw cycles was established. Based on the shape characteristics of the tested stress-strain curves, the compression and shear performance models of recycled glulam influenced by the number of freeze-thaw cycles were proposed.