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大坝混凝土的碱骨料反应(AAR)是制约许多大型水利水电工程建设的技术经济性的一个重要因素,但目前所采用的标准试验方法不能客观地反映AAR病害给实际工程所带来的安全性风险。提出了大坝混凝土对AAR具备“自免疫力”——大坝混凝土自身已经具备的条件,如具有碱活性的人工砂所带入的碱活性石粉、含气、较低的浆骨比等,使其对AAR具有显著的自免疫力。通过砂浆棒快速法试验表明,掺加20%～30%的比表面积为358～812m2/kg的碱活性石粉,可以将砂岩砂的AAR膨胀率降低41%～58%;大坝混凝土中3.5%～5%的含气量可使AAR膨胀率降低约40%。在客观评价大坝混凝土发生AAR破坏的风险时,应该重视这种自免疫力,并应建立能反映大坝混凝土配合比特点、基于大坝混凝土实际表现的试验方法来正确评价工程中的AAR危害。
The alkali-aggregate reaction (AAR) of dam concrete is an important factor that restricts the technical economy of many large-scale water conservancy and hydropower projects. However, the standard test methods adopted at present can not objectively reflect the safety brought by AAR diseases to practical projects Sexual risk. It is proposed that the dam concrete has a “self-immunity” to the AAR and the conditions already possessed by the dam concrete itself, such as the alkali-activated stone powder brought by the artificial sand with alkali activity, the gas-bearing, So that it has a significant self-immunity to AAR. The quick test by mortar bars showed that the AAR expansion rate of sandstone sand can be reduced by 41% -58% with the addition of 20% -30% of alkali-activated stone powder with specific surface area of 358-812 m2 / kg; the 3.5% Air contents of ~ 5% reduce AAR expansion by about 40%. When objectively evaluating the risk of AAR damage to dam concrete, this kind of self-immunity should be paid attention to, and the AAR hazard in the project should be correctly evaluated based on the test method that can reflect the mix proportion of dam concrete and based on the actual performance of dam concrete .