Multi-Phase Model for Flowing Conrete Considering Mixing, Temperature and TIme

本研究的目的是建立考虑搅拌、温度和搅拌后时间影响的流动混凝土多相模型。混凝土是一种由浆体、细集料和粗集料组成的复合材料。细骨料和粗骨料分别假定为单级配的颗粒集合体。浆体被假定为粘性液体。建立了各阶段的运动方程，推导了全流态混凝土的本构关系，描述了考虑平均运动和波动运动的固体颗粒组合体的运动。每一相产生的应力由固体部分的相对运动决定。建立了考虑这些影响的控制方程，考虑了不同阶段之间的相互作用，考虑了正应力对剪切性能的影响。对不同配合比的新拌混凝土进行了敏感性分析。应力-应变速率关系的计算结果表明，粗集料相对产生的应力有重要影响，砂浆和粘性浆体的存在缓解了粗集料颗粒之间的相互作用。建立了新拌混凝土计算机模拟的基本分析框架，考虑了浆体阶段粉末颗粒的流动结构，以模拟新拌混凝土的拌和、拌和后温度和时间等各种行为。

The objective of this study Is to establish the multi-phase model for flowing concrete considering the effect of mixing, temperature adn time after mixing. Concrete Is taken as a composite material of paste, fine aggregate and coarse aggregate. Fine and Coarse aggregate were assumed to particle assemblies having single grading respectively. Paste was assumed as a viscous liquid. Equation of motions for each phase were formulated and constitutive relation of total flowing concrete was derived.MOtion of solid partcle assembly was described considering the mean motion and fluctuation motion. Generated stress In each phase Is governed by the relative motion of solid partcles. Governing equation was formulated considering these effects and Interractions between different phases and the effect of normal stress on shear behavior were considered.Sensitivity analysis was carried out for various mix proportions of fresh concrete. Computed results of stress and strain rate relations described that coarse aggregate phase has a major effect on generated stress and that presence of mortar and viscous paste relax the Interactions between coarse aggregate particles. Basic analytical frame work was established for computer simulation of fresh concrete.Floculation structure of powder particles should be considered In paste phase so as to simulate the various behaviors of fresh concrete such as mixing, temperature and time after mixing.