Creep Properties Of PVA Fiber Engineered Cementitious Composites Based On Fractional Derivatives

A polyvinyl alcohol(PVA)fiber reinforced engineered cementitious composite compared with the traditional concrete has significant advantages,e.g.good toughness,good shock absorption,and good durability,so it has had extensive research and application prospects in the field of bridge pavement structure repair,reinforcement etc.Creep properties of the material about the stress of the structure of the whole life cycle,however,at home and abroad of PVA engineered cementitious composite creep performance study and the corresponding creep model is rarely mentioned.Therefore,based on creep test study long-term deformation law of PVA engineered cementitious composite material and its main influence mechanism,establish a reasonable mix proportion design of creep constitutive relation for the future to provide reliable basis and creep performance evaluation is of great significance.Therefore,based on the theory of fractional order calculus,creep properties of PVA engineered cementitious composite material has carried on the systemic research work,the main research results are as follows:(1)Based on the theory of fractional order calculus,to build a variety of fractional model application situation carries on the discussion in the field of viscoelastic material,shows that the fractional order model in describing the viscoelastic material mechanics behavior has high fitting accuracy and clear physical meaning,fewer parameters,wide applicability advantages and so on.(2)Based on the theory of fractional order calculus,the Riemann-Liouville fractional order derivative components Able dashpot,the classical stick pot instead of the standard linear body,build the fractional order standard linear body creep model as the axis of the PVA fiber reinforced cement matrix composites compressive creep model,has been clear about the physical meaning of each parameter.(3)Self-designed creep loading device completed the axial compression creep test of eight groups of polyvinyl alcohol fiber reinforced cement based composite materials with the standard maintenance of 28d post-axial compressive strength 24.35MPa?51.95MPa.For this new composite material,the creep property of the material is characterized by the average micro-strain of the unit stress.The influence mechanism and effect of water glue ratio and fiber content on creep property of materials were analyzed according to the test results,and the microscopic appearance of the creep was analyzed by scanning electron microscope.(4)Based on creep test data,this paper adopts the Burgers was not standard linear model,mold and fractional order standard linear body creep model fitting analysis on the test data,and compares the different fitting correlation coefficient of the model.The influence of variables on fractional order standard linear body model parameters and the influence of fractional order standard linear creep model parameters on the curves are discussed.(5)Based on the test results,the short-term mechanical properties of reinforced cement based composite materials with polyvinyl alcohol fiber were analyzed,and the feasibility of long-term mechanical properties was predicted.The results show that the larger the transient creep modulus and the smaller the compressive strength,the greater the long-term creep deformation.In this paper,the viscoelastic mechanical behavior of polyvinyl alcohol fiber reinforced cement matrix composites was studied.Based on the fractional order calculus theory,the paper proposed the fractional order standard linear body axial compression creep model,and considered the influence of the water glue ratio and the fiber content in the creep.Results about the description of a reasonable long-term mechanical behavior of PVA fiber reinforced cement matrix composites,a comprehensive grasp deformation characteristics of PVA fiber reinforced cement matrix composites and to predict creep deformation has the important theoretical significance and application value.