南水北调中线工程豫北太行山区石灰岩碱活性特征

Alkalinity activity degree of limestone along the Middle of South-to-North Water Diversion in the Taihang Mountain in northern Henan

活性骨料与水泥中的碱发生化学反应后,吸水膨胀会导致混凝土产生开裂破坏。南水北调中线工程对豫北太行山区12处石灰岩料场采用岩相法、砂浆棒快速法、岩石柱法等试验方法,进行97组岩石碱活性试验。试验主要结论为:寒武系中统张夏组灰岩(∈2zh)和奥陶系中统上马家沟组灰岩(O2s)大部分不含碱活性成分,综合判别为非碱活性,对工程一般不具危害性;奥陶系中统下马家沟组灰岩(O2x)大部分含有碱-硅酸活性成分,个别样品经砂浆棒快速法试验膨胀率大于0.10%,综合判定该组灰岩可能具疑似碱-硅酸活性。

When chemical reaction takes place between the active aggregate and the alkalinity in cement, the active aggregate will expand with water, and destroy the concrete. In this paper, 97 groups of experiments were made on the alkalinity activity degree in 12 limestone material fields with 3 methods, such as lithofacies method, mortar club method, rock pole method, along the Middle of South-to-North Water Diversion in the Taihang Mountain in northern Henan. The major results indicate that most of the ∈ 2 zh and O2 s limestone has no alkalinity activity components, which is judged to have un-alkalinity activity, and with no harm to the project; most of the O2 x limestone has alkalinity-silicic acid activity components, the expansion ratio of some samples is greater than 0.1% with the mortar club method, which is judged to have alkalinity-silicic acid activity.