锦屏一级大坝混凝土骨料碱活性抑制措施的长期有效性研究

为了解决骨料料源选择难题,锦屏一级水电站大坝采取了“组合骨料+高掺粉煤灰+严控碱含量”的砂岩骨料碱活性抑制措施,首次将碱活性骨料应用于特高拱坝混凝土。现在大坝已经运行10 a,有必要对大坝混凝土骨料碱活性抑制措施的长期有效性做出科学评价。对大坝建设期骨料的碱活性抑制措施研究进行了简要的回顾总结,并通过已经运行10 a的大坝混凝土芯样,采用岩相分析、微观形貌和产物分析、加速养护测长和弹性波测试等方法,进行了骨料碱活性抑制措施的长期有效性研究。结果表明,混凝土芯样质量良好,内部没有发生危害性的碱-骨料反应,验证了锦屏一级水电站大坝混凝土骨料采取的碱活性抑制措施的长期有效性。

Long-term Effectiveness of Preventive Measures against Alkali-Aggregate Reaction of Jinping-I Dam Concrete

To address the problem of selecting aggregate sources for Jinping-I dam restricted by environmental and economic factors, alkali-active aggregate had been used in the dam concrete by restraining the alkali-aggregate reaction of sandstone through measures of combined aggregate, high dosage of fly ash, and strict control of alkali content. This was the first time that alkali-active aggregate was adopted to an ultra-high concrete arch dam. Now that the dam has been in operation for about 10 years, it is necessary to scientifically evaluate the effectiveness of the long-term prevention of alkali-aggregate reaction of dam concrete. Researches on the preventive measures against alkali-aggregate activity during dam construction were briefly reviewed and summarized, and then the long-term effectiveness of such preventive measures was examined via petrographic analysis, microscopic morphology and product analysis, accelerated curing length measurement and elastic wave test on dam concrete core samples that have been in operation for 10 years. Test results revealed no harmful alkali-aggregate reaction inside with sound quality of the concrete core sample, which verifies the long-term safety and effectiveness of the alkali-aggregate preventive measures adopted in the dam concrete of Jinping-I Hydropower Station.