冻融作用下活化煤矸石粉混凝土损伤劣化规律

为促进寒冷地区煤矸石在混凝土中的应用,通过机械-微波方式对煤矸石进行复合活化,从表观形貌、质量损失率、相对动弹性模量、抗压强度和劈裂抗拉强度等方面对煤矸石粉混凝土的损伤劣化规律进行了研究,并使用扫描电子显微镜、核磁共振波谱仪和X射线衍射仪等研究了活化煤矸石粉对混凝土抗冻性能的改性机理。结果表明:20%(质量分数)掺量下活化煤矸石粉对混凝土抗冻性能改善效果最好,且经300次冻融循环后,质量损失率和相对动弹性模量分别为2.32%和91.32%,抗压强度和劈裂抗拉强度分别下降了16.40%和26.12%;活化煤矸石粉能填充、细化孔隙,且其二次水化能消耗水泥水化产物Ca(OH)₂,产生C-S-H和C-A-S-H,提升水泥石密实程度,改善孔结构,使大孔占比减少。

Damage and Deterioration Law of Activated Coal Gangue Powder Concrete under Freeze-Thaw

In order to promote the application of coal gangue in concrete in cold regions, the coal gangue was compound activation by mechanical-microwave method. The damage and deterioration law of coal gangue powder concrete was studied from the aspects of apparent morphology, mass loss rate, relative dynamic elastic modulus, compressive strength and splitting tensile strength. The modification mechanism of activated coal gangue powder on the frost resistance of concrete was studied by scanning electron microscope, nuclear magnetic resonance spectrometer and X-ray diffractometer. The results show that activated coal gangue powder has the best effect on improving the frost resistance of concrete when it replaces cement with 20% (mass fraction). After 300 times freeze-thaw cycles, the mass loss rate and relative dynamic elastic modulus are 2.32% and 91.32%, and the compressive strength and splitting tensile strength decrease by 16.40% and 26.12%, respectively. Activated coal gangue powder can fill and refine pores, and its secondary hydration can consume cement hydration product Ca(OH)₂, and produce C-S-H and C-A-S-H, which can improve the compactness of cement paste, improve the pore structure and reduce the proportion of macropores.