Research On The Adhssive Force Of PE-ECC Base D On Tensile Tests And Microstructure Analysis

In this paper,based on the good tensile properties of ultra-high toughness cement matrix composites,desert sand is used to replace some nature sand as fine aggregate.From the macro-tensile test and micro-microscopic analysis,the research and analysis of adhesion of PE-ECC are carried out,the main content is as follows:Made PE-ECC dog-bone tensile specimens of nature sand and desert sand.Through the tensile test,the influence rules of cracking load and ultimate load on tensile properties were analyzed,three indicators of the bonding strength,average number of cracks and average single-seam adhesion were calculated,and the effect of nature sand and desert sand on PE-ECC adhesion from the macro test were clarified.Scanning electron microscope(sem)and X-ray powder diffractometer were used to sample the PE-ECC tensile test specimens of sand and desert sand.The influence of microstructure,hydration product hydrated calcium silicate(c-s-h),matrix interface and transition zone on the bonding force of pe-ecc under different ages was analyzed,and the influence of hydration product calcium silicate on the bonding force of pe-ecc was analyzed qualitatively.The results showed that: 1)through the sample microscopic test,SEM was used to analyze the microstructure of PE-ECC,such as fiber roughness,hydration degree,and compactness,the influence law of fiber roughness,hydration degree and compactness was obtained in 3d,28 d,and the results were consistent with the evaluation index of adhesion,and 7d,14 d and basically consistent with the evaluation index of adhesion.By means of XRD,the hydration products in each phase conform to the SEM test results,and the influence law of the content of the cementing products is consistent with the results of the evaluation index of cohesive force in 3d,7d,and 14 d,28d,and the poor agreement with the results of the evaluation index of cohesive force.2)the development morphology of c-s-h gel in the pe-ecc matrix of nature sand is 0.5-1 times faster than that in the pe-ecc matrix of desert sand.With the development of c-s-h gel morphology,the bond strength and the average number of cracks show an increasing trend.With the increase of c-s-h gel content,the bond strength shows an increasing trend,and the average number of cracks has no significant influence on it.Based on the above experiments,the interface drawing force coefficient is modified by establishing,verifying and analyzing the interface drawing force model of pe-ecc.The single fiber drawing model was studied,and the correlation between the random distribution model and the single fiber drawing model was established by MATLAB,and the interface drawing force of PE-ECC was calculated.By comparing and analyzing the bonding force of PE-ECC between nature sand and desert sand,the following results are obtained: 1)according to the trilinear curve of PE-ECC,the cracking law is converted to bilinear curve;2)based on the drawing model of single fiber,the interface force drawing model of pe-ecc is proposed.Through the theoretical analysis of fiber distribution and interface drawing force,the correction coefficient of interface drawing force is obtained.3)through the load and displacement relationship between PE-ECC of desert sand and nature sand PE-ECC,it is verified that there is a certain relationship between the interface drawing force of nature sand PE-ECC and desert sand PE-ECC.