管片用混凝土黏度的振动法测定研究

Study on the viscosity of concrete for shield segment by the method of vibration

地铁盾构预制管片用混凝土是一种低水胶比、低坍落度且高黏度的混凝土.但对这种混凝土,没有现成的、简便的黏度测试方法可用.针对这一问题,提出了振动测定法.探讨了低水胶比、低坍落度混凝土在测定过程中的流变行为,并通过改变水胶比、砂率等配合比参数,对振动法测定黏度的敏感性进行分析.研究结果表明:振动法对管片用低水胶比、低坍落度混凝土的黏度变化具有敏感性,能有效评价混凝土黏度,指导生产活动;黏度和流空时间具有相同的变化趋势,测定时可用流空时间表征混凝土黏度;管片用低水胶比、低坍落度混凝土在测定过程中的流变行为可用宾汉姆模型表示。

The concrete for shield prefabricated segment is a low slump and high viscosity concrete.But for this concrete,there is no ready and simple viscosity test method available.For this problem,a method of vibration measurement is proposed.The rheological behavior of low water binder ratio and low slump concrete during the determination process is discussed,and the sensitivity of the method of vibration to viscosity is tested by changing the ratio of water cement ratio and sand ratio.The results show that the method of vibration is sensitive to the viscosity change of low fluidity and high viscosity concrete.It can effectively evaluate the viscosity of segment concrete and guide production activities.Viscosity and flow time have the same trend of change,and flow time can be used to characterize the viscosity of concrete.The rheological behavior of concrete with low water binder ratio and low slump concrete during the determination process can be expressed by Bingham model.