新拌混凝土骨料分布均匀性表征方法及其应用

定义了表征骨料分布均匀性的指标——均匀度,借助离散元方法和EDEM软件建立了基于像素的均匀度数字化算法,并基于多个算例验证了该指标的正确性和合理性。研究结果表明:均匀度指标具有明确的物理意义,其取值范围为0～1,且骨料分布均匀性随该指标的增加而增加;基于均匀度的数字化算法与已有方法相比,计算结果规律性高度吻合,但前者更符合常规思维方式,且能够定量和准确反映搅拌过程中骨料分布均匀性的变化;由于基于均匀度的数字化算法考虑了搅拌成型过程中骨料间的相互作用,均匀度亦可表征轻骨料上浮导致的骨料分布均匀性下降等现象。最后对新拌混凝土成型过程中的若干问题进行分析论证并提出了具有工程参考价值的建议。

Characterization method and application of the uniformity of aggregate distribution in fresh concrete

In this paper, the index of aggregate distribution uniformity, uniformity, was defined and the corresponding calculation formula was provided. Thereafter, a pixel-based digital algorithm for uniformity was established by using the discrete element principle and EDEM software, and the rationality and correctness of uniformity were verified by multiple numerical examples. The results showed that the uniformity proposed in this paper had a clear physical meaning, values of which were between 0 and 1, and the uniformity of aggregate distribution increased with the uniformity. The regularity of the calculation results by means of uniformity correlated well with those by other methods. Meanwhile, the uniformity was more in line with the people''s conventional way of thinking, and could reflect the uniformity degree of particle distribution quantitatively and accurately in the mixing process. In addition, the mechanical interaction between aggregates in the mixing process was also considered. Therefore, some phenomena, for example, the decrease of uniformity caused by the floating of lightweight aggregate could be reflected by the uniformity index. Lastly, some problems in the formation of fresh concrete were analyzed and demonstrated, and the corresponding suggestions for practical engineering were also put forward.