快速砂浆棒法检测集料碱活性的岩石和地域局限性及改进措施

Limitations and improvements for alkali aggregate reactivity measurement with Accelerated Mortar Bar Test

综述了快速砂浆棒法的发展和在部分国家或地区的应用经验,研究并提出了其改进措施.文献结果表明,快速砂浆棒法检测集料碱活性具有明显的岩石和地域局限性,对某些种类的变质岩和火成岩可能夸大其危害性,同时可能低估某些碳酸盐、花岗岩、片麻岩和硅质砂岩集料的碱活性.和混凝土棱柱体法膨胀结果相比,快速砂浆棒法膨胀结果不能反映集料在混凝土中的膨胀水平,不宜用于集料活性程度的判定.对世界范围典型集料的试验结果表明,采用能够保持岩石原有结构构造特征颗粒尺寸的中国快速砂浆棒法可以比现有快速砂浆棒法更好地预测集料在混凝土中的膨胀水平,特别是对快速砂浆棒法易于误判的集料类型.

The evolution of Accelerated Mortar Bar Test （AMBT） and its application in various regions of the world were reviewed. Literature results showed that AMBT had limitations in testing the alkali reactivity of some rock types with varied reliability from region to region. The alkali reactivity of some metamorphic and volcanic rocks could be overestimated, while the alkali reactivity of some carbonates, granite, gneiss and siliceous sandstones underestimated. In comparison with the results of Concrete Prism Test（CPT） , expansions in the AMBT could not reflect the expansion levels of tested aggregates in concrete and thus should not be used to classify the reactivity of aggregates. Experimental results showed that the alkali reactivity of aggregates, especially of aggregates that were misjudged in the AMBT, could be reasonably predicted with Chinese Accelerated Mortar Bar Test（CAMBT） , in which aggregate particles that could maintain the microtextural characteristics of rocks were used.