Experimental Study On The Mechanical Properties Of Anti-cracking Functional Material Of ECC-concrete

PVA fibre reinforced cement matrix composites(PVA-ECC)is a kind of composite material,which is made by adding a certain amount of polyvinyl alcohol fiber in cement mortar.It has a relatively high bending and tensile strength,ultimate elongation,larger crack resistance and deformation resistance,impact resistance,abrasion resistance,permeability resistance and high fatigue strength,etc.The application of PVA-ECC can effectively improve the durability of engineering.Referring the existing researches on the PVA-ECC and the experimental data obtained by our subject group,this paper further explores the optimal mixture ratio of ECC reinforced with Chinese PVA.Based on the design principles of functionally gradient material;the PVA-ECC is placed in the tensile region of reinforced concrete to replace some parts of ordinary concrete beams,which developes a kind of composite material.In the binding area of interface between the ECC and concrete material,both of two kinds of material permeate mutually.They can be changed into anti-cracking fuctional material of ECC-concrete within a certain range.To further analyze mechanical properties of the component(structure)which was made of ECC-concrete composite,it must be necessary to investigate the mechanical properties of anti-cracking fuctional material of ECC-concrete which is used in the binding area of interface between ECC and concrete material.This research has determined the optimal mixture ratio of ECC reinforced with Chinese PVA through experiment,and further carry out experiments and theoretical studies according to the mechanical properties of anti-cracking fuctional material of ECC-concrete.Now,the research contents are as follows:(1)The research explored the mechanical properties of PVA-ECC through the cube compression and four-point bending test.Two experiments prepared 27 test specimen.The researcher analyzed the experiment result to determine the optimun proportion of PVA-ECC.Based on the material of optimum proportion of PVA-ECC,the research has acquired the value of tensile strain by deducing the material's span deflection.What' more,the research used the existing experiment data of tensile strain to clarify the relationship of span deflection and tensile strain of PVA-ECC.(2)The research investigated the mechanical properties of anti-cracking fuctional material of ECC-concrete under the tension and compression through the cube compression test and splitting tensile test respectively.Both of tests prepared 36 test specimens respectively.30 test specimens of them used domestic PVA fibre and 6 test specimen of them as control group used PVA fibre made in Japan.Based on the linear fitting on experiment data,the research determined the relationship between the thickness of ECC and ratio of cube compressive strength and uniaxial compressive strength of anti-cracking fuctional material of ECC-concrete.Considering the experiment statistic,the research advised the value of compressive strength and splitting tensile strength in the case of different concrete strength,thickness of ECC material as well as different interface treatment case.(3)The research investigated the bending toughness of anti-cracking fuctional material of ECC-concrete through four-point bending test.The experiment in this paper prepared 36 test specimens.30 test specimens of them used domestic PVA fibre,and 6 test specimen as control group used PVA fibre made in Japan.The study aims to analyze the influnce of following factor such as concrete strength,the thickness of ECC as well as interface processing mode on the material' bending toughness.