An experimental and numerical investigation of coarse aggregate settlement in fresh concrete under vibration
An experimental and numerical investigation of coarse aggregate settlement in fresh concrete under vibration
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DOI：
10.1016/j.cemconcomp.2021.104153
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发表时间：
2021-07-05
影响因子：
10.5
通讯作者：
Savija, Branko
中科院分区：
文献类型：
--
作者：
Cai, Yuxin;Liu, Qing-feng;Savija, Branko
新拌混凝土需要振动压实，填充模具并达到密实状态。在压实过程中，粗骨料（CA）往往会沉降，影响硬化混凝土的均匀性，并最终影响其长期耐久性。在这项研究中，一个3-D，多阶段的数值模型，新拌混凝土的发展，以更好地了解CA下的振动沉降。根据斯托克斯定律考虑CA在振动混凝土中的沉降速率，采用分段筛分法确定混合料的标定流变参数。模型预测结果表明，振动时间对CA沉降的影响最大，其次是CA粒径，而CA密度和混合料的塑性粘度对CA沉降的影响较小。通过实验验证了预测结果的有效性。该模型提供了一种新的方法来理解和估计CA的沉降行为。
Fresh concrete needs vibration to compact, fill the mould and reach a dense state. During the compaction process, coarse aggregates (CAs) tend to settle, affecting the homogeneity and eventually the long-term durability of hardened concrete. In this study, a 3-D, multi-phase numerical model for fresh concrete is developed for better understanding the CA settlement under vibration. The settlement rate of the CA in vibrated concrete is considered based on the Stokes law, and the calibrated rheological parameter of mixtures is determined by the segmented sieving method. The model prediction shows that the vibration time has the greatest effect on CA settlement, followed by the particle size of CAs, whereas the density of CAs and the plastic viscosity of mixtures contribute a little compared with the aforementioned factors. Through experimental tests, the validity of prediction results is well verified. The proposed model provides a new method to understand and estimate the settlement behaviour of CAs.