Study On The Expansion Performance Of Sleeve Grout

In the steel sleeve grouting connection technology,the expansion performance of the sleeve grout plays a crucial role in ensuring the integrity and seismic performance of the fabricated building structure.The preparation of micro-expansion sleeve grouting is often carried out using a sulphoaluminate cement-silicate cement-gypsum ternary system.The change of expansion ratio in the grouting slurry of the system is not easy to control,resulting in frequent shrinkage of the test piece,excessive expansion rate or Insufficient expansion in the later period.In this paper,the orthogonal design experiment is used to prepare the sleeve grouting material,and the influence of sulphoaluminate cement,Portland cement and gypsum on the swelling performance of the grout is analyzed by using the range and variance,and the sleeve grouting with the performance meeting the specifications is obtained.Material mix ratio.On this basis,the effects of three mineral admixtures of fly ash,silica fume and slag powder and two admixtures on the expansion properties of ternary sleeve grout were studied.XRD,TG-DSC and SEM techniques were used.The changes in the types,quantities and morphologies of the swelling hydration products during the consolidation and hardening of the grout were studied,and the relevant expansion mechanism was analyzed.Research indicates:(1)The incorporation of mineral admixture into the sleeve grout can form a more effective expanded gelling material system.Mineral admixture mainly reduces the formation of shale gangue by slowing the hydration speed of cement clinker,diluting the amount of sulphoaluminate cement and gypsum,and finally affecting the development of expansion performance.The fly ash,silica fume and slag powder of suitable dosage can effectively control the expansion performance of the grout.(2)Admixtures also have a significant effect on the swelling properties of the grout.Appropriate amount of admixture can adjust the expansion of the grout,and the mixed admixture will produce a synergistic effect,which has a more significant effect on the expansion.The mechanism by which the admixture affects the expansion is to control the development of the slurry expansion property by reducing the Ca2+ concentration required for ettringite formation or hindering the C3 A hydration reaction to form calcium vanadium.(3)The strength development and expansion development of the sleeve grout should be coordinated.When the admixture is used,whether it is a single admixture or a compound admixture will make the coordination between expansion and strength worse and worse.When an additive is used to regulate the expansion performance,the amount of incorporation is strictly controlled.(4)It is obtained through microscopic experiments that the amount of acicular ettringite formed in the slurry is significantly reduced when the mineral admixture is incorporated,and the shrinkage CSH gel is produced more,and the expansion process of the grout is delayed;When admixture is added,the ettringite in the slurry becomes fine and the quantity is obviously reduced.Later,it gradually develops into non-expanded rod-like crystal,and the development speed of the swelling property of the grout is obviously suppressed.