Study On Mechanical Properties And Durability Of Polyvinyl Alcohol Fiber Fly Ash Concrete

Polyvinyl alcohol(PVA)fiber fly ash concrete is a new type of fiber composite material,which has the advantages of high tensile strength and good crack resistance.However,there are few studies on PVA fiber fly ash concrete at present,and they are all researches on the dosage of PVA fiber and the single mechanical properties and durability.In order to further study the performance of PVA fiber fly ash concrete,based on orthogonal test method,the effects of PVA fiber length,PVA fiber content,fly ash content and water cement ratio on mechanical properties of PVA fiber fly ash concrete,sulfate erosion resistance and salt freezing resistance.The main research contents are described as follows:(1)The effects of four factors on the mechanical properties of PVA fiber fly ash concrete were studied by conducting the compressive,splitting tensile and flexural tests.Based on the test data,the range,factor effect,variance and linear regression analysis were conducted,so that the mechanical properties of different orthogonal combinations could be predicted.The study showed that in the test range,the water cement ratio had the greatest effect on compressive strength and splitting tensile strength,and PVA fiber content had the greatest effect on flexural strength.Besides the water cement ratio,the fly ash content had the greatest influence on the compressive strength,and PVA fiber content had the greatest influence on the splitting tensile strength.(2)The effects of dry-wet cycle times on the relative dynamic elastic modulus and mass loss rate of specimens were studied by the dry-wet cycling-sulfate test.After 60dry-wet cycles,the compressive,splitting tensile and flexural tests were carried out to study the influence of four factors on the sulfate corrosion resistance of PVA fiber fly ash concrete.Based on the test data,the range,factor effect,variance and linear regression analysis were conducted to predict the mechanical properties of different orthogonal combinations under60 dry-wet cycles.The results showed that within the scope of the test,the water cement ratio had the greatest effect under 60 dry-wet cycles.Besides the water cement ratio,fly ash content had the greatest influence on compressive strength,splitting tensile strength and flexural strength.(3)The influence of the freeze-thaw cycle times on the relative dynamic elastic modulus and mass loss rate of the specimen was studied by conducting the freeze-thaw cycle-sulfate test.After 125 freeze-thaw cycles,the compressive and splitting tensile tests were conducted to study the influence of four factors on the freezing resistance of PVA fiber fly ash concrete.Based on the test data,the range,factor effect,variance and linear regression analysis were performed to predict the compressive and split tensile strength of different orthogonal combinations under 125 freeze-thaw cycles.The results showed that in the scope of this test,the water cement ratio had the most influence.Besides the water cement ratio factor,fly ash content had the greatest influence on the compressive and split tensile strength.(4)The scanning electron microscopy test of PVA fiber fly ash concrete in different environments was carried out,and the fiber distribution inside the concrete under different environments,as well as the morphology of the generated products,and the influence of the generated products on the concrete were analyzed.