Study On Basic Mechanical Properties And Freezing-Thawing Properties Of Textile Reinforced ECC

In order to improve the problems of low crack resistance and poor toughness of concrete materials and further satisfy practical engineering applications,fiber concrete materials are attracting widespread attention.In this paper,based on Xuzhou City’s key Research and Development plan "Research on the Stress Mechanism and Degradation of Textile/ECC Wall Materials",the basic mechanical properties of Engineered Cementitious Composites(ECC)and the basic mechanical properties and freezing-thawing properties of Textile Reinforced Engineered Cementitious Composites(TRE)were studied.The main research contents and results are as follows:(1)The effects of fly ash content and water-binder ratio on ECC tensile and flexural mechanical properties were studied.The test results show that within a certain range,with the increase of fly ash content and water-binder ratio,the ultimate tensile strength and ultimate flexural strength of ECC specimens decrease.In addition,with the increase of fly ash content,the ultimate tensile strain and ultimate span deflection of ECC specimens showed an upward trend.When the water-to-binder ratio increases from 0.28 to 0.32,the tensile and flexural properties of the specimen are greatly reduced,and the ultimate tensile strain and ultimate mid-span deflection are the lowest.(2)The effects of the number,types of textile and the surface treatment of textile and the amount of PVA fibers on the tensile and flexural mechanical properties of TRE were studied under conventional conditions.The test results show that,compared with the single-layer TRE specimens,the ultimate tensile stress and ultimate flexural strength of the double-layer TRE specimen are significantly improved,and the rigidity is increased.Compared with carbon textile reinforced TRE specimens,the tensile and flexural mechanical properties of basalt textile reinforced TRE specimens are lower.The ultimate tensile stress and ultimate flexural strength of the TRE specimens showed a decreasing trend after the carbon textile surface was dipped in glue and sand,but the ultimate tensile strain and ultimate mid-span deflection increased.In addition,when the PVA fiber content is increased from 1.0%to 2.0%,the tensile and flexural properties of the TRE specimen are improved.(3)The effects of different freezing-thawing environments,freezing-thawing cycles,textile layers,types and textile surface treatment,and PVA fiber content on thetensile and flexural mechanical properties of TRE were studied under the action of freezing-thawing environment cycles.The test results show that under the action of the freezing-thawing cycle of the mixed solution of sulfate and chloride,the mechanical properties of the TRE specimens are greatly reduced.As the number of freezing-thawing cycles increases,the tensile and flexural mechanical properties of TRE specimens tend to decrease.The ultimate tensile stress and ultimate flexural strength of the double-layer TRE specimens are higher than that of the single-layer TRE specimens,but the ultimate tensile strain and ultimate mid-span deflection are reduced.Compared with carbon textile reinforced TRE specimens,the tensile and flexural mechanical properties of TRE specimens reinforced with basalt textile are significantly reduced.The tensile and flexural bearing capacity of TRE specimens reinforced with dipped sticky sand fiber braided textile The force decreases,and the ultimate tensile stress and ultimate span deflection increase.With the increase of PVA fiber content,the tensile and flexural mechanical properties of TRE specimens improved.(4)Theoretical analysis of the flexural capacity of TRE is carried out,and the calculation formula of flexural capacity of TRE in conventional environment and freezing-thawing environment is established.The calculation results are in good agreement with the test data.There are 53 pictures,13 tables and 122 references in this paper.