Experimental Studies on Volume Stability of Shrinkage Compensating Concrete Used in Diversion Tunnel of Pubugou Hydropower Project

摘要

According to the requirements of construction and operation of diversion tunnel concrete of Pubugou hydropower station,the technical scheme that selfcompacting concrete (SCC) is used at the top layer of diversion tunnel and pumping concrete is used at the bottom layer was proposed.Functional chemical admixtures and Grade I fly ash is used to optimize hydration heat curve of cement paste and decrease the final hydration heat.MgO-type expansive additive and ettringite-based expansion source additive are used to compensate autogenous shrinkage and temperature shrinkage at various stages of hydration and hardening of concrete. The concrete that has microexpansion at early age and expansion-stable after 14 days is prepared,which meets the requirements of workability,mechanical performances and durability of diversion tunnel concrete. The result of steel ring test shows that stable expansion stress of concrete is more than 0.3MPa,meeting the design requirement. The full course of the autogenous shrinkage of SCC which is used at the top layer is investigated by stages from the casting with noncontact sensor. The technical measures above guarantee the volume stability of diversion tunnel concrete of Pubugou hydropower station.