Study on axial tensile properties and piezoresistive response of carbon fibric reinforced cementitious matrix
To investigate the tensile properties and piezoresistive response of carbon-glass hybrid fiber grid reinforced cementitious matrix(C-GFRCM),12 sets of C-GFRCM plates were subjected to uniaxial tensile tests.The influence of mortar type,prestress level,adhesive,and the arrangement of glass fiber sheet on their tensile properties and fiber utilization rate was analyzed.The changes in electrical resistance of carbon fiber bundles during the tensile process of C-GFRCM plates and the response mechanism of specimen stress state,as well as the law of resistance response and crack occurrence position,were studied.The results showed that prestressed C-GFRCM plates mostly exhibited a single crack failure mode,while epoxy resin adhesive C-GFRCM plates mostly experienced fiber pullout failure,and C-GFRCM plates with geopolymer adhesive saw fiber slip and pullout failure.The prestressing process mainly enhances the cracking load of C-GFRCM plates,and the higher the prestress level,the more significant the enhancement effect,with a maximum increase of 267％.Dispersion pasting of glass fiber cloth using epoxy resin adhesive can significantly enhance the ultimate load of C-GFRCM plates,with a maximum increase of 320％.During the tensile process,the piezoresistive response of C-GFRCM plates exhibited three stages:in the elastic stage,the resistance showed no significant change;in the crack development stage,the resistance began to increase and fluctuate at the crack initiation point;in the crack enlargement and failure stage,the resistance at the main crack increased significantly.The resistance response can accurately characterize the stress state of C-GFRCM plates and determine the occurrence position of cracks.The sensitivity of resistance of C-GFRCM plates to stress state varies changes with different design parameters.
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