活性Al_2O_3对碱骨料反应(ASR)的抑制与制动作用

Weaken and Brake Effect of the Active Al_2O_3 to the Alkali-aggregate Reaction(ASR) in the Concrete

通过试验发现 ,在富含活性Al2 O3的混凝土体系中 ,虽然仍有可能发生碱 骨料反应(ASR) ,但在相同条件下 ,总膨胀率减小 ,膨胀期缩短 ,并最终趋于稳定 ,也就是说 ,活性Al2 O3既能抑制又能制动ASR膨胀 .其原因是 :在活性Al2 O3存在的情况下 ,ASR的反应产物不再是无限吸水膨胀的碱 硅酸凝胶 ,而是碱 铝硅酸盐凝胶 ,这类凝胶具有很强的结晶倾向 ,一旦结晶成沸石类矿物 ,其体积将不再因水分子的进出而胀缩 .倘若控制得当 。

From the experimental results, it is found that in the concrete system with high active Al 2O 3 contents, the ASR expansion happenes, but the total quantity and the continued period of it is smaller than that of the concrete with common Al 2O 3 contents at the same conditions. The active Al 2O 3 can not only weaken but also brake the ASR expansion. The reason is that the products of the ASR is the alkali alumi silicates but not alkali silicates hydrogel in the concrete of richer active Al 2O 3 presents. This hydrogel has a high tendency of crystallization. Once the zeolite minerals are formed, their volumes will not expand or contract because of the water getting in or out. If the quantity of the Al 2O 3 is properly introduced, the ASR expansion can be forecast and used.