Experimental Study on Backfilling Micro-expansive Self-compacting Concrete in Anchor Slot
In order to solve the problems of cracking and voiding caused by uncompacted vibration or large plastic deformation of concrete in anchorage slot of unbonded prestressed structure in long-distance diversion tunnel,the effects of fly ash content,expansive agent content and water-binder ratio on strength and limited expansion rate were studied.The micro-expansion self-compacting concrete was designed,and its free volume deformation and autogenous shrinkage were measured.The results show that when the water-binder ratio is 0.40,the content of fly ash is 25%,and the dosage of expansive agent is 30kg/m3,the 28d flexural tensile strength is 4.77MPa and the 28d compressive strength is 53.6MPa,respectively,and the impermeability grade is greater than W11.The autogenous volume deformation of concrete is 20×10-6 in 60d,which tends to be basically stable,and the drying shrinkage is about-460×10-6 in 90d.The moisturizing curing of micro-expansion self-compacting concrete should be strengthened,and the time of moisturizing curing should be prolonged to facilitate the performance of expansive agent.
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