Experimental Study on Pulsatile Flow of Concrete Flowing in Pipe

混凝土在管道中的脉动流动会对新拌混凝土泵送后的性能以及泵送管道本身产生不利影响。此外，从施工现场的环境角度来看，管道中的脉动混凝土流所产生的噪音可能超过可接受的水平。本研究项目旨在开发一种新型的泵送混凝土系统，以最大限度地减少管道中的脉动。一种小规模设计的泵送装置具有两个液压缸：一个用于主流，另一个用于补充流，分别允许以任意水平布置相应流的脉动。采用可视化技术确定补充流的脉动水平，使补充流与主管道混合后流经主管道的混凝土脉动流最小化。本研究的结论是，通过将补充流的脉动水平与主管道的一定流量相匹配，可以在不引起不利脉动的情况下泵送混凝土。脉动的水平。研究还发现，混凝土中单位体积粗骨料含量对管内混凝土的脉动流态有影响。

A pulsatile flow of concrete flowing in pipe will adversely affect the property of the fresh concrete after being pumped as well as the pumping pipe itself. In addition, the noise resulting from the pulsating concrete flow in pipe might exceed an acceptable level from environmental points of view in the job site.This research project has been conducted to develop a novel system for pumping concrete with a minimizing degree of the pulsation in the pipe. A pumping devise designed on a small scale has two hydraulic cylinders : one for a main stream and the other for a supplemental stream, respectively, that permit to arrange the pulsation of respective stream with arbitrary levels. A visualization technique was employed to determine satisfactory levels of the pulsation of the supplemental stream that resulted in minimizing the pulsatile flow of concrete flowing through the main pipe after being combined with the supplemental stream.This research concludes that pumping concrete could be operated without causing an adverse pulsation through the pipe by arranging the pulsation levels of the supplemental stream with the main flow of a certain level of the pulsation. Also, it was found that the content of coarse aggregate per unit volume in concrete influenced the manner of pulsating flow of the concrete in pipe.