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

本研究的目的是建立流动混凝土的多相模型，考虑搅拌、温度和搅拌后时间的影响。混凝土是由浆体、细骨料和粗骨料组成的复合材料。细集料和粗集料分别被假定为具有单一级配的颗粒集合体。膏状物被假定为粘性液体。建立了各相的运动方程，推导了全流态混凝土的本构关系，考虑了平均运动和脉动运动，描述了固体颗粒集合体的运动。在每一相中产生的应力由固体颗粒的相对运动控制。建立了考虑这些影响的控制方程，并考虑了各相之间的相互作用和正应力对新拌混凝土抗剪性能的影响，对新拌混凝土的不同配合比进行了敏感性分析。应力和应变率关系的计算结果表明，粗骨料相产生的应力和砂浆和粘性膏体的存在松弛粗骨料颗粒之间的相互作用的主要影响。建立了新拌混凝土计算机模拟的基本分析框架，认为应考虑粉粒在浆体阶段的絮团结构，以模拟新拌混凝土的拌和、温度和拌和后时间等各种行为。

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.