浅变质岩骨料碱活性特征及抑制措施
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贵州省交通运输厅科技项目(2010 122 007,2019 122 003)


Alkali Activity and Inhibition of Low Grade Metamorphic Rock Aggregates
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    摘要:

    针对黔东南不同地区浅变质岩的岩性和骨料碱活性,研究了混凝土碱含量对碱骨料反应(AAR)的影响,并分析了试样的微观表面形貌及化学组成.结果表明:黔东南地区浅变质岩饱和抗压强度的离散性较大,各组岩石均为硅酸盐类岩石;未经粉煤灰抑制处理的浅变质岩骨料砂浆试件14d膨胀率全部超过01%,均存在潜在的碱硅酸反应(ASR)危害;粉煤灰对碱骨料反应的抑制作用明显,经粉煤灰抑制处理的浅变质岩骨料砂浆试件14d膨胀率均有所降低,且大部分未超过003%;混凝土碱含量越大,碱骨料反应越快速,反应周期越长,膨胀率越大,最佳碱含量应控制在10%以内.扫描电子显微镜X射线能谱(SEMEDS)结果显示:与未发生碱骨料反应的砂浆试件相比,已发生碱骨料反应的砂浆试件中骨料表面有蜂窝状的碱硅酸凝胶产物生成,骨料表面有细裂纹,并出现了Si和Na元素富集现象.

    Abstract:

    Lithology and alkali activity of low grade metamorphic rock aggregates in different regions of southeastern part of Guizhou province were analyzed, the influence of total alkali contents on alkali aggregate reaction(AAR) was analyzed, and the optimum proportion of low grade metamorphic rock aggregates inhibition technology was investigated by orthogonal test. Results indicate that the saturated compressive strength of the low grade metamorphic rock aggregates is more discrete, and theses samples in each group are silicate rock aggregates. The 14d expansion rate of the mortar specimens is more than 01%, indicating the potential harm from alkali silicate reaction(ASR). The inhibition of fly ash on AAR is obvious, and the expansion rate of 14d in each group has been reduced, and most of them do not exceed 003%. The greater the total alkali content of concretes, the faster the AAR, the longer the reaction period and the higher the expansion rate. The alkali content should be limited in 1%. From SEM EDS, comparing the specimen without AAR, it has been seen that a honeycomb like silicate gel product is formed on the aggregate surface, the aggregate surface has fine cracks, and the Si and Na elements are enriched in the specimen in which the alkali aggregate reaction occurred.

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杨黔,蒋正武,张兵兵,周飞.浅变质岩骨料碱活性特征及抑制措施[J].建筑材料学报,2019,22(6):941-948

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  • 收稿日期:2019-06-13
  • 最后修改日期:2019-07-25
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  • 在线发布日期: 2019-12-25
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