天然火山灰质材料对骨料碱活性的抑制研究

Research on inhibition of alkali aggregate reactivity with natural pozzolans

用岩相法、砂浆长度法、砂浆棒快速法和混凝土棱柱体法检验了某工程砂岩骨料的碱活性,并采用砂浆棒快速法研究不同品种天然火山灰质材料对该砂岩ASR膨胀的抑制效果。试验结果表明该砂岩骨料具有潜在的ASR活性,不同品种天然火山灰质材料对骨料ASR抑制效果差异较大,抑制效果最差的为玄武岩微粉,掺量在40%以上才能把这种砂岩的ASR膨胀量控制在非碱活性范围之内;抑制效果最好的是浮石微粉,掺量20%就有明显的抑制效果,与I级粉煤灰的抑制效果相当。

The alkali reactivity of sandstone aggregate of a hydropower station engineering is determined by means of petrographic analysis,accelerate mortars-bar test and mortar length method as well as concrete prism expansion method.The effect of natural pozzalans on inhibition of the expansion is evaluated by the method of mortars-bar test.The experimental results show that the sandstone aggregate has potential alkali-silica reaction（ASR）activity.The basalt powder has the worst restrain effect and the mortar expansion due to ASR could be reduced to a non-reactive range by substituting cement more than 40% powder.The pumice powder has the best effect,and there is the obvious restrain effect with adding 20% pumice powder which is equivalent to the inhibition effect of first grade fly ash.