三峡工程混凝土的碱-骨料反应试验研究

三峡工程大坝混凝土将利用闪云斜长花岗岩碎石作粗骨料，用斑状花岗岩制成的砂作细骨料。由于花岗岩含有应变石英，普遍出现波状消光，另外在应力集中区，石英形成不同类型的位错，因此其碱活性反应具有缓慢、持续时间长的特点，从地质环境、岩相、物理、化学等多方面进行了研究，采用多种方法进行了对照检验。结果表明，花岗岩的矿物组成主要是长石、石英、黑云母和少量角闪石或绿泥石等，用岩相法、化学法、砂浆长度法、小棒快速法、砂浆棒快速法、混凝土棱柱体法等进行测定属非活性，在低碱条件下，不会导致危害性膨胀，但在高碱条件下，砂浆膨胀率在数年后仍继续增长，为确保工程安全，应严格控制水泥含碱量。

Experimental study on alkali-aggregate reaction of concrete of Three Gorges dam

For the dam construction of Three Gorges Project (TGP), coarse aggregate were made of black granite and the fine aggregate were made of porphyritic granite. The granite contains strain quartzes, which have oscillatory extinction. In the stress cncentration zone, the quartzes would bring about some kinds of line defects. The alkali-aggregate reaction was slow and took a long time. The aggregates were studied from aspects of geological environment, lithofacies, physics and chemistry. The aggregates were analyzed for the alkali reactivity potential by applying petrography method, chemical mothod, mortar bar method, rapid method and concrete method. The result show the aggregates are of no alkali reactivity. When the alkali content is low, epznsion of the concrete will not be damaging. When it is high, expansion of the concrete would be increasing for some years. In order to insure safety of TGP, the alkali content of cement must be controlled strictly.