Develpoment of Pumpability Testing Machine of Fresh Concrete

本课题涉及新拌混凝土可泵性试验机的研制。本项目两年来的成果如下：(1)建立管流模型混凝土可视化试验方法研制了以吸收性聚合物为液相，轻骨料和焦炭为固相的模型混凝土。设计了吸收聚合物的配合比，使其在新拌混凝土中具有与实际砂浆相似的流动性。并且可以直观地显示管流中固相与液相的运动规律。然后利用视频平台和A/D转换器，开发了粒子运动的时域测量系统。从可视化试验的结果可以清楚地了解锥形管中流动混凝土的变形和堵塞机理以及分岔液中的离析过程。(2)新拌混凝土离析电阻测量系统的研制研制了实际新拌混凝土的电阻测量系统，以间接表示混凝土中骨料的体积比。提高了电极的耐磨性。根据使用该测量系统的现场试验结果，提出了流动混凝土离析和临界阻塞条件的评价方法。我们就上述开发申请了两项专利。(3)两相材料固液流动偏析模型的建立基于可视化试验(1)的信息，建立了流动混凝土的两相模型，并对管道流动中新鲜混凝土的偏析和阻塞进行了模拟。从这个模拟中，得到了以下结果：(a)分离，定义为固相的体积变化，在锥剂中加速。(b)液相的高粘度导致管道内的压力相当高，产生高的偏析阻力，从而使总物料具有良好的流动性。少

This project was concerned with development of pumpability testing mochine of fresh concrete.The results of this project in two years are given as follows.(1) Establishment of vesualized testing method for modeled concrete in pipe flowWe developed modeled concrete, which consists of absorbent polymer as liquid phase and lightweight aggregates and coke as solid phase. Mix proportion of absorbent polymer was designed so that its fluidity was similar to that of actual mortar in fresh concrete. And the solid phase in liquid phase of pipe flow could be visualized to follow the motion of solid phase. Then with the use of video deck and A/D converter, the measuring system of particle motion in time domain was developed. From the results of this visualized test, we could clariify the deformation and blocking mechanism of flowing concrete in tapered pipe and segregation process in bifurcated potion.(2) Development of electrical resistance measuring system for segregation of fresh concrete in pi … More pe flowWe developed the electrical resistance measuring system for actual fresh concrete to represent the volume ratio of aggregates in concrete indirectly. Then the wear out resistance of electrode was improved. From the site experimental results with the use of this measuring system, the evaluation method for segregation and critical blocking condition of flowing concrete was proposed. we applied for two patents on the above developments.(3) Development of segregation model for solid-liquid flow of two phase materialBased on the information from the visualized test (1). two phase model of flowing concrete was developed and the simulation of segregation and blocking of fresh concrete in pipe flow was counducted. From this simulation, the following results were derived.(a) Segregation, defined as the volume change of solid phase, is accelerated in the taper potion.(b) High viscosity of liquid phase leads to the considerable high pressure in pipe and to the high segregation resistance, which results in the good fluidity of total material. Less