Study On Mechanical Properties And Microstructure Of Surface Coating Modified Carbon Fiber Reinforced Cement-based Composites

Carbon fiber reinforced cement-based composites?CFRC?are excellent in strength,durability and workability,and have broad application prospects in engineering construction.However,carbon fiber as a reinforcing phase,restricting its full performance in CFRC mainly includes:?1?Carbon fiber is difficult to achieve dispersion distribution in CFRC,especially the combination between carbon fiber and cement matrix at the agglomeration place deteriorates,affected by When the force is broken,it is easy to produce stress concentration and be the first to break,but it reduces the mechanical properties of CFRC;?2?The compatibility between the carbon fiber surface and the cement matrix and aggregate is poor,the interface bonding ability is weak,and the bonding strength is low,which restricts CFRC Mechanical properties.Hydroxyethyl cellulose?HEC?is used as the dispersion medium.By controlling the concentration of the HEC solution and pre-dispersing the carbon fiber bundles with the aid of mechanical agitation,the carbon fiber bundles can be opened to form well dispersed carbon fibers Monofilament.Pretreatment can improve the dispersion of carbon fibers,and lay the foundation for a better distribution of carbon fibers in the cement matrix in the future.A continuous,uniform thickness,no protrusions and no cracking Si O₂coating was prepared on the surface of carbon fiber by Sol-gel method.After the carbon fiber modified by Si O₂ coating is mixed into the cement matrix and aggregate,coating modified carbon fiber reinforced cement-based composites?CMCFRC?are obtained.Si O₂ coating improves the wettability between carbon fiber and cement matrix and aggregate,improves the interface bonding ability and enhances the mechanical properties of the material.In this study,multiple groups of CMCFRC samples were prepared by adjusting the parameters of carbon fiber coating,length,and content.By comparing and analyzing the flexural and compressive strength of CMCFRC samples,the parameters of carbon fiber length,content,and Si O₂ coating were discussed Effect on the mechanical properties of CMCFRC.Scanning electron microscopy?SEM?was used to observe the microstructure of the sample destruction interface to evaluate the dispersion state of carbon fiber and Si O₂modified carbon fiber in cement-based composites and the reinforcement mechanism during mechanical failure.