Random non-convex particle model for the fraction of interfacial transition zones (ITZs) in fully-graded concrete
Random non-convex particle model for the fraction of interfacial transition zones (ITZs) in fully-graded concrete
复制标题
全级配混凝土中界面过渡区 (ITZ) 比例的随机非凸粒子模型
DOI：
10.1016/j.powtec.2017.10.009
复制
发表时间：
2017
影响因子：
5.2
通讯作者：
Huaifa Ma
中科院分区：
文献类型：
--
作者：
Wenxiang Xu;Zhongmei Han;Liang Tai;Qihan Ding;Huaifa Ma
界面过渡区(ITZ)的比例等结构形态对混凝土的整体物理力学性能有很大影响。然而，通过传统的实验方法和目前提出的简单模型很难确定ITZ的比例。在这项工作中，设计了一个全面的数值框架，以统计地获得全级配混凝土中非凸集料周围的ITZ分数。在数值框架下，通过随机序列加法(RSA)生成由均匀水泥浆体、特定级配的非凸集料和定维ITZ组成的三相二维随机非凸颗粒模型，以表征微观销售的全级配混凝土的几何模型。非凸粒子的几何形态通过基于椭圆的单元的变形被数学地参数化。这种操作可以严格控制非凸粒子的几何形状，精确地实现等维界面层的拓扑几何，满足著名的核壳结构的要求。将所提出的随机非凸粒子模型与单点概率函数相结合，通过蒙特卡罗模拟对ITZ的分数进行了统计分析。此外，系统地研究了全级配混凝土中集料的形状、级配、掺量、最大尺寸和ITZ尺寸等几何特征对ITZ掺量的影响。重要的是，首次探索了非凸集料几何形状和级配影响的定量方法。作为一项关键的Itz特性，本研究的贡献可进一步用于评价全级配混凝土的物理力学性能。
The structural configuration such as the fraction of interfacial transition zones (ITZs) has been found that can seriously impact the whole physico-mechanical properties of concrete. However, the fraction of ITZs is difficultly determined by traditional experimental methods and simple models proposed so far. In this work, a comprehensive numerical framework is devised to statistically obtain the fraction of ITZs around non-convex aggregates in fully-graded concrete. In the numerical framework, the authors generate a three-phase two-dimensional random non-convex particle model consisting of homogeneous cement paste, non-convex aggregates with a specific gradation and ITZs with a constant dimension, through a random sequential addition (RSA) scheme so as to characterize the geometric model of fully-graded concrete at a microscopic sale. The geometric morphology of a non-convex particle is mathematically parameterized in terms of the deformation of an ellipse-based cell. Such the operation can strictly govern the geometric shape of non-convex particle and precisely realize the topological geometry of an interfacial layer with a constant dimension to meet the requirement of the famous core-shell structure. Combining the proposed random non-convex particle model with the one-point probability function, we statistically analyze the fraction of ITZs by the Monte Carlo simulations. Plus, the influences of the geometric characteristics of aggregates including the shape, gradation, fraction and the maximum size and the ITZ dimension on the fraction of ITZs are systematically investigated in fully-graded concrete. Importantly, a quantitative manner on the effects of the geometric shape and gradation of non-convex aggregates is explored for the first time. As a critical ITZ property, the present contribution can be further drawn into assessing physico-mechanical properties of fully-graded concrete.