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本文采用快速冻融的试验方法,研究了碾压混凝土在水中的抗冻性。测定冻融后试件质量损失、动弹性模量、抗压与抗折强度,并利用扫描电镜观察混凝土微观结构。结果显示:冻融次数不大于200次时,随着冻融次数的增加,碾压混凝土的相对动弹模、抗折强度、抗压强度均有所降低;但250次冻融强度略有增长;扫描电镜观察发现,冻融过程中混凝土内部出现了明显的微裂纹,同时水泥水化产物由针状向网状结构转变。
In this paper, fast freezing and thawing test method was used to study the frost resistance of roller compacted concrete in water. After freeze-thaw, the mass loss, dynamic elastic modulus, compressive strength and flexural strength were measured. The microstructure of concrete was observed by SEM. The results show that the relative dynamic elastic modulus, flexural strength and compressive strength of roller compacted concrete decrease with the increase of the number of freeze-thaw cycles when the number of freeze-thaw cycles is not more than 200. However, the strength of freeze-thaw cycles increases slightly after 250 cycles. Scanning electron microscopy showed that there were obvious micro-cracks in the concrete during the freeze-thaw process, and the hydration products of cement changed from acicular to reticular structures.