乌东德大坝是世界上首座全坝应用低热水泥的特高拱坝,大坝混凝土采用“低热水泥+35% Ⅰ级粉煤灰”胶凝材料体系设计方案,全面掌握大坝混凝土性能对工程安全运行至关重要。对乌东德大坝胶凝材料水化性能、混凝土力学性能、混凝土变形性能、混凝土绝热温升等开展了试验,研究了乌东德大坝低热水泥混凝土5 a龄期的性能发展规律。研究表明,乌东德大坝混凝土用胶凝体系在3 a龄期后水化程度为90.4%,水化进程达到准稳定状态;从性能发展规律可分析得出,大坝混凝土最终抗压强度为70.5 MPa、弹性模量约42 GPa、干缩约380×10^-6、自生体积变形约20×10^-6,较同条件下中热水泥混凝土,具有长期强度高、弹性模量相当、长期体积稳定性好等特点;乌东德大坝混凝土绝热温升的最终收敛值为27.9 ℃,3 a龄期后绝热温升年增长仅0.1 ℃,后期无“翘尾”现象。综合分析可知,乌东德大坝混凝土的各项性能约1 a龄期后逐步进入缓慢收敛状态,3 a龄期后基本达到稳定状态。

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.