负温防冻剂混凝土的界面显微结构与性能

INTERFACE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF CONCRETE WITH ANTIFREEZING ADMIXTURE AT SUBZERO TEMPERATURES

研究了不同种类的防冻剂、矿物掺合料对正、负温下水泥净浆、砂浆及混凝土力学性能的影响。通过对比实验表明:水泥净浆、砂浆及混凝土在正、负温条件下抗压强度的变化规律存在显著差异,这取决于其内部显微结构,尤其是界面显微结构的差异。利用显微硬度计、扫描电镜、能谱分析、X射线衍射研究了防冻剂混凝土界面过渡区的范围、元素分布、钙硅比及氢氧化钙的取向度。结果表明:防冻剂能够改善负温下混凝土的界面显微结构,防冻剂和矿物掺合料的复合使用可为负温混凝土提供理想的界面显微结构。

The mechanical properties of hardened cement paste, mortar and concrete with different antifreezing admixture and mineral admixture cured at 20℃ and -20℃ were investigated. The distinct difference on the compressive strength changes of hardened cement paste, mortar and concrete maybe attributed to the bigger difference within the interface transition zone （ITZ）. Micro-hardness test, scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction were used to analyze the range of the ITZ, element distribution, calcium oxide/silica ratio and orientation of calcium hydroxide. The results show that the anti-freezing admixture can improve the ITZ microstructure in concrete at sub-zero temperatures. Antifreezing admixture combined with mineral admixture can provide an ideal interface microstructure for concrete at sub-zero temperatures.