Properties And Aligned Self-healing Technology Of Glass Microtube For Cement-based Composites

The incorporation of a glass tube containing a repairing agent into a cement matrix(GSCM)is one of the technical ways to achieve self-healing of cement-based materials.When the glass tube in the matrix is randomly distributed in three dimensions,the glass tube parallel to the crack is not easily broken,and the repairing agent is difficult to flow out,which affects the self-healing effect.Adjusting the orientation of the glass tube perpendicular to the crack can improve self-healing performance.In order to improve the orientation of the glass tube and improve the self-repairing property,the glass micro-tubes are rotated by the magnetic field to adjust the glass microtubes to be perpendicular to the crack direction,in this way,the aligned glass tube self-healing cement-based material(AGSCM)is prepared.The mechanical and crack transmission performance tests are carried out to investigate the self-healing properties of AGSCM and GSCM.The main research work and achievements are as follows:(1)Investigated the preparation method of aligned glass micro-tube self-healing cement-based composites.An external uniform magnetic field was applied to the freshly mixed glass tube-steel fiber cement-based self-healing material to make the glass micro-tuber to be perpendicular to the crack when the mold filled with cementitious composite was compacting on the vibration table.The AGSCM specimens was prepared.According to the test,the orientation of the glass tube is good,and the direction coefficient can reach 0.89.(2)Through three-point bending test before and after healing,the effect of glass tube orientation,direction angle,carrying steel fiber quantity on the flexural strength recovery rate,load-fracture opening displacement and toughness of AGSCM and GSCM specimens were analyzed quantitatively.The results show that,with the increase of the number of steel fibers and the decrease of the direction angle of the glass tube,the AGSCM specimens has a significantly improved recovery rate and deformation ability compared with GSCM.(3)Through crack permeability and water absorption test,the effect of glass tube orientation and crack width on the permeability and water absorption coefficient of AGSCM and GSCM specimens were analyzed quantitatively.The results show that,micro-crack resistance to permeation and water absorption of aligned glass tube self-healing cement-based material is better than randomly distributed glass tube self-healing cement-based material.Under the same conditions,the difference in permeability and the difference in water absorption coefficient between the aligned and randomly distributed glass tube self-healing specimens decreased with the increase of the crack width.(4)The mechanical model of the rotation of steel fiber driven glass tube is derived.The mechanism model of the glass tube orientation affecting the outflow of the repair agent and the number of glass tubes in the tube was established.Comparing the penetration test with the theoretical results,the reliability of the model was verified.The results show that when the glass tube is oriented,the number of glass tubes in the crack and the outflow of the repair agent in the tube are more than the random distribution of the glass tube.The aligned glass tube self-healing cement-based composite material has higher filling degree and better impermeability.The use of steel fiber orientation technology to drive the glass tube orientationally distribution improves the material repair efficiency and reduces the amount of glass tube.