振动搅拌对复掺预制梁混凝土性能的影响研究

Study on the Influence of Vibration Mixing on the Properties of Concrete Mixed with Precast Beams

文中测试了两种搅拌方式下混凝土的坍落度、坍落度经时损失、含气量、表观密度、抗压强度以及抗冻性,采用热重分析仪、扫描电镜和压汞仪分别测试混凝土的水化产物含量、微观形貌及孔径分布.结果表明:与强制搅拌相比,虽然振动搅拌对复掺胶凝体系预制梁混凝土的坍落度以及坍落度经时损失均产生不利影响,但对混凝土的含气量、表观密度、抗压强度、抗冻性均有显著的提升作用;振动搅拌使得复掺胶凝体系预制梁混凝土3d龄期的CH含量提高了22.4%,少害孔、有害孔、多害孔含量及总孔隙量分别减少16.1%、42.3%、37.9%、27.6%,界面过渡区无明显微裂缝且结构密实.振动搅拌通过增加复掺胶凝体系预制梁混凝土水化产物数量、改善界面过渡区微观形貌以及细化孔径分布,从而提高混凝土的致密性、抗冻性和抗压强度.

The slump,slump loss over time,air content,apparent density,compressive strength and frost resistance of concrete under two mixing methods were tested.The content of hydration products,micro-morphology and pore size distribution of concrete were tested by thermogravimetric analyzer,scanning electron microscope and mercury intrusion meter respectively.The results show that,compared with forced mixing,vibration mixing has an adverse effect on the slump and slump loss of precast beam concrete mixed with cementitious system,but it has a significant effect on improving the air content,apparent density,compressive strength and frost resistance of concrete.Vibration and stirring can increase the CH content of precast beam concrete mixed with cementitious system by 22.4%at 3d age,and reduce the contents of few harmful holes,harmful holes,many harmful holes and total porosity by 16.1%,42.3%,37.9%and 27.6%respectively.There are no obvious micro-cracks in the interface transition zone and the structure is compact.Vibration mixing can improve the compactness,frost resistance and compressive strength of concrete by increasing the number of hydration products of precast beam concrete mixed with cementitious system,improving the micro-morphology of interface transition zone and refining the pore size distribution.