为研究高强混凝土冻融损伤机理及其与抗压强度之间的关系,采用RapidAir结合金相显微镜的方法,实现对混凝土细观冻融损伤的连续观察,探究了细观结构对冻融的敏感程度以及细观破坏对宏观破坏的影响规律.结果表明:对高强混凝土而言,较低的含气量和较大的气泡间隔系数并不意味着较差的抗冻性;孔隙群的冻融响应敏感,且微裂缝出现较早,该区域的缺陷增长能与冻融前期混凝土抗压强度线性下降很好地对应,但此时混凝土的抗压强度下降并不明显;相对孤立的孔和砂浆与粗骨料的界面过渡区较不敏感,这些区域出现损伤后,混凝土的抗压强度逐渐非线性下降,预示着混凝土即将冻碎.
In order to figure out the freeze-thaw damage mechanism of high-strength concrete and its relationship with compressive strength,a method combining RapidAir and digital metalloscope was employed to investigate the meso-damages of concrete throughout the freeze-thaw test.The meso-structure's sensitivity to freeze-thaw damage and the relationship between meso-damage and macro-damage were studied.Results show that high-strength concrete with low air content and large spacing factor does not result in poor freeze-thaw resistance.Pore groups are sensitive to freeze-thaw damage,and micro-cracks tend to appear early between them.This phenomenon corresponds well with the compressive strength loss in the early stage of freeze-thaw cycles (FTCs),but these micro-cracks will not lead to a drastic compressive strength loss.Isolated pore and interracial transition zone are not sensitive to freeze-thaw damage.If these areas are damaged,the compressive strength will drop non-linearly,indicating the coming macroscopic failure.
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