Study On The Repair Characteristics Of Microcapsule Self-repairing Cement-based Materials Under Cyclic Loading

The cement-based materials in service not only bear static load but also periodic dynamic load.Under the action of load,the cement-based material will inevitably crack,and the traditional crack repair method has some shortcomings such as high cost and environmental pollution.Microcapsule self-repair technology has become a new development trend.In this paper,the self-healing cement based materials of microcapsules were studied.Through uniaxial compression,cyclic load test and microscopic test,the effects of various influencing factors on the macroscopic dynamic mechanical properties and microstructure of self-repairing cement-based materials were discussed,and the relationship model between macroscopic dynamic mechanical properties and microscopic pore structure parameters was established.The main research results are as follows:(1)Carry out uniaxial compression test to study the influence of microcapsule dosage,precompression stress,curing age and sample state on the deformation and strength characteristics of microcapsule self-repairing cement-based materials,and provide a basis for cyclic load test.(2)Cyclic load tests with different loading frequency and strain amplitude were carried out to study the self-repairing cement-based materials,analysis under certain conditions of microcapsule dosage and curing age,the influence law of loading frequency/strain amplitude on the dynamic mechanical parameters and repair characteristics of self-repairing cement-based specimens.Thus learned:When the content and the curing age are unchanged,the dynamic peak strength tends to decrease with the increase of loading frequency,the damping ratio and the dynamic modulus of elasticity tend to increase,with the increase of strain amplitude,the dynamic peak strength and damping ratio tend to increase,and the dynamic elastic modulus decreases.(3)The structural parameters of three kinds of holes(initial,precompression damaged and precompression repaired)were studied by mercury injection method.The effects of microcapsule content,curing age,different loading frequency and different strain limits on the microstructure of self-repairing cement-based materials were analyzed.Through research,the effect of loading frequency on microstructure is most obvious.(4)The relationship between the parameters of the pore structure and the characteristics of the damping ratio and the dynamic modulus of elasticity is established to analyze the relationship between them.and then through MATLAB multiple regression analysis,it is concluded that the correlation coefficient after multivariate variable fitting is greater than the correlation coefficient of single variable fitting,and the effect of fitting is improved.