关键词: 大坝混凝土, 低热水泥, 长期性能, 乌东德水电站, 高拱坝

Abstract: Wudongde Dam is the world’s first ultra-high arch dam to adopt low-heat cement in the whole dam. The cementitious material for dam concrete comprises low heat cement plus 35% grade-I fly ash. The performance of the dam concrete is of crucial importance to the safety of the project. We looked into the properties and developments of five-year age low-heat cement concrete of Wudongde Dam by examining the hydration performance of cementitious material, the mechanical performance, deformation performance, as well as adiabatic temperature rise of concrte. Our findings unveil that the hydration degree of the cementitious system amounts to 90.4% after three-year age, indicating the hydration process reaches a quasi-stable state. The ultimate compressive strength of dam concrete is 70.5 MPa, according to the development law, and the modulus of elasticity is about 42 GPa, the drying shrinkage around 380×10^-6, and the autogenous volume deformation about 20×10^-6. The low-heat cement concrete has higher long-term strength, equivalent elastic modulus and better long-term volume stability than medium-heat cement concrete under the same conditions. The final convergence value of adiabatic temperature rise is 27.9 ℃. The annual growth of adiabatic temperature rise is only 0.1 ℃ after three-year age, with no further abrupt rise in the later stage. In conclusion, the properties of Wudongde dam concrete gradually enter a slow convergence period after about one year, and basically reach stable after three-year age.

Key words: dam concrete, low-heat Portland cement, long-term properties, Wudongde hydropower station, high arch dam