| Compared with other kinds of fibers,polypropylene fiber as a synthetic fiber has the advantages of high corrosion resistance and high cost performance.Adding it to cement-based materials can effectively improve the disadvantages of cement-based materials such as poor tensile properties and fragility under tension,so it has been widely used.Modified polypropylene fibers with high elastic modulus and high tensile strength were obtained by modifying the surface of polypropylene fibers.Waste glass as a solid waste can only be recycled by landfill,but grinding it into powder can be used as a volcanic ash material to strengthen the cement matrix.In this paper,waste glass powder and modified polypropylene fibers are added into cementitious materials to prepare a green high performance fiber reinforced cementitious material(GP-MPP-FRCC).In this paper,modified polypropylene fibers(fiber volume fraction2%)with lengths of 6mm,12 mm and 20 mm were used for two-by-two blending,while different proportions of fly ash and waste glass powder were used instead of cement.The working and mechanical properties of the materials were investigated by flow test,flexural test,compressive test,tensile test and four-point bending test,and the micro-level mechanism of the materials was investigated by XRD test and SEM scanning electron microscope test,and finally the optimal calculation of the fit ratio was carried out by combining the multi-factor gray correlation degree decision model,and the following conclusions were obtained:(1)The study on the net slurry ratio of waste glass powder instead of cement shows that the addition of waste glass powder has a small effect on the working properties such as water content,but will significantly improve the flowability of the mix,and significantly improve the mechanical properties of the material.(2)For different ratios of GP-MPP-FRCC,different damage patterns appeared in flexural and compressive tests.By analyzing the effects of different fiber blending and waste glass powder admixture on the flexural and compressive strength and load-displacement curves of GP-MPP-FRCC at 3d,7d and 28 d ages,it was found that fiber blending and admixture of waste glass powder could enhance the flexural and compressive strength of cementitious materials.(3)The effect of fiber blending and waste glass powder admixture on the tensile properties of GP-MPP-FRCC was investigated by tensile tests.Combining the different cracking modes and tensile load-median deflection curves of the tests,it was found that the fiber blending and the addition of waste glass powder could improve the tensile strength of the material,but two different behaviors of strain softening and strain hardening occurred when different lengths of fibers were blended.(4)The effects of different fiber blends and waste glass powder doping on the flexural properties of GP-MPP-FRCC were investigated by four-point bending tests on flat plates,and the toughness index method of ASTM-C1018 was combined to evaluate GP-MPP-FRCC.The results show that the blended fibers can improve the toughness and absorption capacity of the material,and the waste glass powder can increase the cracking deflection and peak deflection of the material.(5)The microstructure of GP-MPP-FRCC was analyzed by XRD test and SEM scanning electron microscope test,and it was found that the incorporation of waste glass powder leads to more hydration products production,improves the microstructure of cement matrix,and enhances the fiber-matrix interface.(6)The optimal ratio of GP-MPP-FRCC was calculated by using the gray correlation degree decision model for the workability and mechanical properties of GP-MPP-FRCC with multiple factors,and the G100F20 ratio was determined as the optimal ratio for the overall performance. |
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