干燥环境下粉煤灰混凝土表面假性碳化研究

回弹法检测混凝土强度需要测量混凝土表面的碳化深度,混凝土表面的碳化深度测量在干燥环境下将受到一定的影响。该文通过设置烘干组、干燥组、标养组试块及墩柱A、墩柱B进行回弹法试验。从试验中发现,干燥环境下混凝土的碳化,在喷上酚酞时出现明显分界线,随着时间推移,碳化区颜色变粉再变红,碳化分界线往混凝土表面移动。干燥环境下粉煤灰混凝土的碳化受三方面影响,一是由于水泥熟料占比减少,产生的Ca(OH)2减少;二是由于粉煤灰的二次水化消耗Ca(OH)2;三是干燥环境会进一步影响水泥的水化反应及碳化,导致Ca(OH)2结晶析出。

It is necessary to measure the carbonation depth of concrete surface by rebound method,and the measurement of carbonation depth of concrete surface will be affected in dry environment.In this paper,the rebound test is carried out by setting up oven-drying group,drying group,standard maintenance group,as well as pier A and pier B.It was found that the carbonation boundary of concrete in dry environment appeared obviously when phenolphthalein was sprayed on it,and the carbonation zone turned pink and red with time.The carbonation of fly ash concrete under dry environment is affected by three aspects:first,the proportion of cement clinker decreases,resulting in the decrease of Ca(OH)2;second,the secondary hydration of fly ash consumes Ca(OH)2;third,the dry environment will further affect the hydration reaction and carbonation of cement,resulting in the crystallization of Ca(OH)2.