Study On Tensile Mechanical Properties Of Alkali-resistant Glass Fiber Fabric Reinforced Concrete

Textile reinforced concrete(TRC)has been widely used in thin-walled structures,and engineering repair,reinforcement fields on account of the feature of light weight,high strength and good ductility.Alkali-resistant glass fiber has the advantages of high tensile strength,strong corrosion resistance and low price,which is convenient for its popularization and application in civil engineering field.Therefore,the quasi-static tensile test of alkali-resistance glass textile reinforced concrete(ARG-TRC)was carried by universal testing machine.The effects of the volume fraction of the warp and weft fibers and the impregnation of epoxy resin on the failure patterns and tensile mechanical properties of the composites were studied.The distribution of cracks and strains were obtained by digital image correlation(DIC)analysis,and the tensile constitutive model was obtained by trilinear fitting.The main investigations and results of this paper are as follows:(1)The cement mortar matrix with high fluidity,high permeability and high strength is designed and prepared,and the compressive strength and flexural strength of the matrix are obtained by simple mechanical property test.(2)The quasi-static tensile tests of single fiber bundle and fiber mesh strip were carried out by MTS universal testing machine to explore the influence of the impregnation of epoxy resin and the amount of non-main stressed fiber bundle on the failure pattern and tensile mechanical properties.The results show that the tensile strength and peak strain of a single bundle of warp fibers are larger than those of the weft fibers.The warp fibers can be selected as the main stress direction of the fiber.The amount of non-main stressed fiber has no obvious effect on the tensile strength and deformation.Epoxy resin impregnation is beneficial to enhance the bond of the fiber filament,make the force more uniform,and improve the tensile strength of the single bundle fiber,but the improvement of the tensile strength of the fiber mesh strip is not obvious.The tensile failure of the single bundle without impregnation is mainly manifested as the tensile failure of the filament with scattered cross section,while the single bundle with impregnation is manifested as the brittle failure with neat cross section.The failure pattern of the fiber mesh strip is basically the same as that of the single fiber bundle,the difference is that the fracture does not occur simultaneously.(3)The quasi-static tensile tests were carried out on four layers of ARG-TRC by universal testing machine to explore the influence of different weft fiber volume fractions(0vol%,0.06vol%,0.13vol%,0.20vol%,0.48vol%and 0.96vol%)and the impregnation of epoxy resin on the failure morphology and tensile mechanical properties.By trilinear fitting of the tensile stress-strain curve,the simplified model was obtained and compared with the ACK model.The results show that the weft fiber volume fraction has little effect on the tensile mechanical properties and failure modes of ARG-TRC.Both non-impregnated and impregnated specimens show the fracture and pull-out failure of the fibers in the state of multiple cracks,and the crack direction is mainly flat crack.(4)The quasi-static tensile tests were carried out on ARG-TRC with different longitudinal fiber volume fractions(0.24vol%,0.49vol%,0.73vol%and 1.09vol%)by a universal testing machine.By trilinear fitting of the tensile stress-strain curve,the simplified model was obtained and compared with the ACK model.The results show that the tensile mechanical properties and failure modes of ARG-TRC are closely related to the warp fiber volume fraction.The tensile strength,peak strain and toughness of ARG-TRC increase significantly with the increase of the warp fiber volume fraction.At the same time,when the volume fraction(_fV)is lower than the critical value,the specimens show fiber breakage and pull-out;when _fV is higher than the critical value,the specimens show multi-crack fiber fracture and pull-out.With the increase of the volume fraction,the number of crack increases significantly,and the average crack spacing decreases significantly.In addition,the crack-spacing calculation formula was modified based on the existing crack-spacing calculation model and experimental data,which show good consistency with the literature data.(5)DIC analysis was used to obtain the displacement and strain evolution laws of ARG-TRC at different moments in the tensile process,the strain distribution and crack width on the specimen surface at failure.The results show that there is no significant correlation between the strain at the crack and the weft fiber volume fraction of the specimen.Compared with the specimen without impregnation,the strain at the crack of the impregnation specimen should be smaller,and the strain at the main crack is obviously larger than that of other cracks.With the increase of the volume fraction of the longitudinal fiber,the strain at the crack decreases obviously and the crack width decreases.