碱活性石英砂岩粉对砂浆体积变化影响试验研究

Influence of alkali activated quartz sandstone powder on volume change of cement mortar

混凝土中的碱与混凝土骨料中所含的无定形SiO_(2)发生化学反应,会在骨料表面生成碱-硅酸反应(ASR)凝胶,凝胶吸水久会导致混凝土胀裂。为了解各种因素对ASR膨胀量的影响,控制岩粉掺量、温度、湿度、碱度及岩粉粒径等开展了一系列试验。结果表明:温度、湿度、碱度越高,ASR膨胀反应越剧烈,膨胀趋势随龄期增长出现不同程度的扩大,但岩粉并未表现出理论上的碱活性膨胀反应;粒径为0.08~0.16 mm的石英砂岩粉其掺量的提高可有效抑制砂浆后期的膨胀;而粒径小于0.08 mm的石英砂岩粉对于ASR膨胀量影响不显著,可在一定程度上有效改善试件后期体积稳定性。

Alkali in concrete reacts with amorphous silica contained in concrete aggregates, then alkali-silica reaction(ASR) gel generates on the aggregates surface.Water absorption by the gel leads to concrete cracking.In order to understand the influence of various factors on the expansion of ASR,a series of experiments were carried out to control the content of rock powder, temperature, humidity, alkalinity and particle size of rock powder.The results showed that the higher the temperature, humidity and alkalinity, the more intense the ASR expansion reaction was, and the expansion trend expanded to different degrees with the increase of age, but the rock powder did not show the alkali active expansion reaction in theory.The increase of the content of 0.08 ~ 0.16 mm quartz sand powder could effectively inhibit the expansion of mortar at the later stage, while the quartz sand powder with particle size less than 0.08 mm had no obvious effect on the expansion of ASR,which can effectively improve the volume stability of the specimen at the later stage to a certain extent.