Study On The Basic Mechanical Properties And Failure Mechanism Of Polypropylene Fabric Concrete

In engineering construction,the mechanical properties of concrete are often improved by adding polypropylene fiber.Polypropylene fiber is also the main raw material for civil clothing and industrial cloth.Polypropylene fabric blended with polypropylene fiber has become an important component of waste fabric due to its wide range of use,large storage and difficulty in decomposition.The influence of polypropylene fabric as admixture on the mechanical properties of concrete matrix was analyzed.The feasibility of polypropylene fabric replacing polypropylene fiber as concrete admixture was studied.The main research results are as follows:(1)The preparation method and property of mixture of polypropylene fiber fabric reinforced concrete and polypropylene fiber reinforced concrete based different contents.It can be found that,the preparation method of polypropylene fiber fabric reinforced concrete is same to the plain concrete,and there is no different in property of the mixtures.The different content of polypropylene fiber fabric lead the slumps of comcrete reduced 1.5%?7.5%,while there are 3%?14%increasment compared to the polypropylene fiber reinforced concrete.The peaceability isn't change remarkable even the content of polypropylene fiber fabric changed,and this characteristic is good for the engineering practice.(2)Based on the self-made trigger system,the characteristic of instantaneous crack development of polypropylene fiber fabric reinforced concrete and polypropylene fiber reinforced concrete are achieved.The energy absorb capacity of these two kinds of concrete with different curing ages and contents is compared with plain concrete based on the compressive load test.It can be found that,the polypropylene fiber fabric reinforced concrete content with 0.9 kg/m3 polypropylene fiber fabric performed the biggest critical intensity and peak strength,it performed brittle characteristics when destoried.Improve the content(e.g.1.2 kg/m3 and 1.5 kg/m3)or reduce the content(0.6 kg/m3)will lead the change of compressive property.The larger value of content will lead the lower strength of polypropylene fiber fabric reinforced concrete before standard curing age(28 days),and this characteristic go against of the increasement if mechanical properties.(3)The characteristic and the change rule of polypropylene fiber fabric reinforced concrete and polypropylene fiber reinforced concrete in three-point bending test and the splitting test is achieved and the result is compared with the plain concrete.The results shows that,the polypropylene fiber fabric can improve the flexural strength and splitting tensile strength of concrete,but it still lower than that of polypropylene fiber reinforced concrete with the same fiber content.The addition of polypropylene fiber fabric is harmful to the flexural property of concrete when the content exceed 0.9 kg/m3(e.g.1.2 kg/m3 and 1.5 kg/m3),but it can improve the splitting tensile property.Because the increasement of the curing age lead the brittle characteristics of concrete become more remarkable,so the value of increase amplitude of the polypropylene fiber fabric and polypropylene fiber to the concrete is reduced,however the promotion of the 0.9 kg/m3 content polypropylene fiber fabric and polypropylene fiber to the concrete is the most significant.(4)The uniaxial compression constitutive model with different curing ages and fiber fabric contents are achieved based on strain-stress curve and Hogenestand and Zhenhai Guo model,and the coefficients is determined by differential evolution algorithm,DE.Meanwhile,the conversion relation of compressive strength and flexure strength,and compressive strength and splitting tensile strength were established,and the relationship of compressive strength and elasticity modulus based on different curing age and fibric/fiber contents were also established.The result revealed that,the different curing ages and fibric/fiber content affected significantly on the descending branch of stain-stress curve,and they have affected the relationship of compressive strength and flexure strength,and compressive strength and splitting tensile strength without law.Moreover,the relationship of compressive strength and elasticity modulus of polypropylene fiber fabric reinforced concrete and plain concrete are similarity,but different form polypropylene fiber reinforced concrete.In this paper,the effects on mechanical property of adding different content of polypropylene fiber fabric and polypropylene fiber to plain concrete is achieved based on dffferent curing ages.The reinforcing mechanism of fiber fabric-concrete matrix and fiber-concrete matrix were revealed.This study provides a scientific basis and new ideas for the analysis of mechanical properties of fabric concrete and the recycling of waste fabrics.