Stress-strain behaviour of spontaneous combustion gangue coarse aggregate concrete under FRP tube confinement

Due to its poor mechanical properties and working performance, spontaneous combustion gangue coarse aggregate concrete (SCGAC) is currently limited to non-load-bearing structures. However, these defects can be effectively improved by fiber reinforced polymer (FRP). To capture the axial compression behaviour of FRPconfined SCGAC, a total of 32 cylinders specimens (150 mm in diameter and 300 mm in height) were tested under monotonic axial compression with replacement ratio and FRP tube thickness as test variables. Test results show that, in comparison to ordinary concrete in similar conditions, the strength of FRP-confined SCGAC decreases by 5.6%-39.8% while the ultimate compressive strain increases by 11.7%-110.8%. When SCGAC confined with FRP tube, its strength increases by 1.87-4.44 times, and the ultimate strain of each specimen increased by 6.12-16.19 times. In addition, the crack forms and dilation properties of SCGAC also show significant differences when compared with ordinary concrete. Finally, a new design-oriented model for FRPconfined SCGAC is generated within the framework of the existing models for FRP-confined ordinary concrete, with necessary modification to compensate for the effect of aggregate characteristics.

Automated summary

Fiber reinforced polymer (FRP) can effectively improve the mechanical properties and working performance of spontaneous combustion gangue coarse aggregate concrete (SCGAC), allowing it to be used for load-bearing structures. FRP-confined SCGAC exhibits higher strength and ultimate compressive strain compared to ordinary concrete, showing significant differences.