纤维曲率对界面过渡区初始微观结构影响的计算机模拟

COMPUTER SIMULATION OF EFFECT FOR FIBER′S CURVATURE ON FRESH INTERFACIAL TRANSITION ZONE MICROSTRUCTURE

借助计算机模拟技术,以单粒径球形粒子体系在不同尺度的圆截面纤维周围堆积时固相体积分数分布为例,研究了纤维直径与粒子直径比值变化对纤维浆体界面过渡区初始微观结构的影响。将模拟计算结果与单粒径球形粒子体系在平集料表面的固相体积分数分布曲线进行对比。研究了纤维曲率对多尺度球形粒子体系在纤维表面固相体积分数分布曲线的影响,并将该模拟计算结果与多尺度球形粒子体系在平集料表面的固相体积分数分布曲线进行对比。结果发现:无论是对单粒径球形粒子体系而言,还是对多尺度球形粒子体系而言,初始界面过渡区的微观结构与纤维的曲率无关。球形粒子沿不同曲率纤维周围的固相体积分数分布曲线的形式与在平集料表面周围的粒子固相体积分数曲线的分布形式相同,曲线第一个峰值点的位置(即初始界面过渡区厚度的位置)也都出现在模型水泥平均质量半径的位置附近,水胶比的降低,会使初始界面过渡区的厚度略有减小。因此,可以用平集料表面浆体结构取代圆截面纤维浆体结构来研究各种因素对初始界面过渡区微观结构的影响。

In virtue of computer simulation approach, the monosize spherical particles were packed around the fiber with circular section of different diameter. Curves of volume fraction of solid vs the distance to the surface of the fiber were used to study the influence of the ratio for fiber diameter to particle diameter on the initial microstructure of interfacial transition zone (ITZ). These curves were compared with that from the system where monosize spherical particles were packed along the flat plane of aggregate. Results indicate that, no matter the spherical particles system is monosized or multisized, the fresh ITZ microstructure is not relevant to the curvature of fiber. The shape of the curve between volume fraction of solid and distance from the surface of fiber is similar to that from the system where the spherical particles were packed along the flat plane of aggregate. In all cases, the horizontal coordinate of the first peak of the curves is located around mean weigh radius of the particles. With the decreasing of ratio of water to cement, the thickness of ITZ reduces slightly. Therefore, the structure of ITZ between aggregate with flat plane and cement paste can be used as replacement of the structure of ITZ between fiber with circular section of different diameter and cement paste to study the influence of various factors on the fresh ITZ microstructure.