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How do discharge rate and pipeline length influence the rheological properties of self-consolidating concrete after pumping?
Cement & Concrete Composites ( IF 10.5 ) Pub Date : 2021-08-25 , DOI: 10.1016/j.cemconcomp.2021.104231
Wenkai Shen 1 , Qiang Yuan 2 , Caijun Shi 1 , Youhong Ji 3 , Rong Zeng 3 , Wei Li 3 , Youwu Wu 3 , Lilin Lao 3 , Zheng Chen 4 , Fumin Li 1
Affiliation  

Pumping changes the rheological properties, workability and construction performance of fresh concrete. However, there were limited knowledges on influences of discharge rates and pumping distances on the fresh properties of concrete. In this paper, effects of various discharge rates and pipeline lengths on rheological properties of self-consolidating concrete (SCC) after pumping were studied. A total of 12 SCC mixtures with the slump flow of 650–745 mm were pumped in pipelines with measured lengths of 342 m, 545 m, and 1044 m by constant discharge rates ranging between 5.1 and 11.4 L/s. Rheological properties were measured before and after pumping. Physical conditions of SCC during pumping, including pressure, shear, and temperature were estimated theoretically and experimentally. Moreover, the total organic carbon in the pore solution of SCC mixtures was measured to evaluate the change of superplasticizer adsorptions after pumping. Test results indicated that, due to pumping, the yield stress increased; the initial tangential viscosity decreased and the shear-thickening phenomenon was eliminated. The changes of yield stresses and viscosity were encouraged by discharge rates. Besides, lower initial slump flow of SCC exhibited a larger slump flow loss after pumping due to a higher shear rate experienced during pumping. The yield stress and viscosity after pumping increased with the increase of pipeline length at similar discharge rates, but decreased with the pipeline length under similar pumping pressures. The adsorption of superplasticizer increased after pumped at relative low discharge rates (5.2–5.7 L/s), but decreased at discharge rates of 7.7–10.8 L/s.



中文翻译:

泵送后自密实混凝土的流变性能如何影响排放速率和管道长度?

泵送改变了新拌混凝土的流变特性、和易性和施工性能。然而,关于排放速率和泵送距离对混凝土新鲜性能的影响的知识有限。在本文中,研究了各种排放速率和管道长度对泵送后自密实混凝土 (SCC) 流变特性的影响。共有 12 种坍落度为 650-745 mm 的 SCC 混合物被泵入测量长度为 342 m、545 m 和 1044 m 的管道中,排放速率范围为 5.1 到 11.4 L/s。在泵送之前和之后测量流变特性。泵送过程中 SCC 的物理条件,包括压力、剪切力和温度,均通过理论和实验进行了评估。而且,测量 SCC 混合物孔隙溶液中的总有机碳,以评估泵送后减水剂吸附的变化。试验结果表明,由于泵送,屈服应力增加;初始切向粘度降低,剪切增稠现象消除。排放速率促进屈服应力和粘度的变化。此外,由于泵送过程中的剪切速率较高,SCC 的较低初始坍落流在泵送后表现出较大的坍落流损失。泵送后的屈服应力和粘度在相似的排放速率下随着管道长度的增加而增加,但在相似的泵送压力下随着管道长度的增加而减小。以相对较低的排放速率(5.2-5.7 L/s)泵送后,减水剂的吸附增加,

更新日期:2021-08-30
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