Improvement of Polyethylene Glycol in Compatibility with Polycarboxylate Superplasticizer and Poor-Quality Aggregates Containing Montmorillonite
Publication: Journal of Materials in Civil Engineering
Volume 29, Issue 9
Abstract
Polycarboxylate superplasticizer (PCE) is widely employed in cement-based material to reduce water demand and increase fluidity, and even to improve durability of concrete. Generally, aggregates occupy more than 70% weight of concrete, and those poor-quality aggregates containing clay minerals, especially montmorillonite (Mt), often make PCE ineffective and significantly reduce the workability of concrete; this phenomenon is referred to as poor clay tolerance of PCE. Currently, the poor clay tolerance seriously restrains the practical application of PCE. In this study, the mechanism behind the improvement of the clay tolerance in the presence of polyethylene glycol (PEG) was investigated to explore a valid way to enhance the clay tolerance. Specifically, the clay tolerance in the presence of PEG was assessed with the fluidity of cement-Mt paste. Total organic carbon analyzer was performed to analyze the adsorption behavior of PCE and PEG. The microstructure of the intercalated Mt was characterized with X-ray diffractometer, transmission electron microscopy, Fourier-transform infrared spectrometer and thermogravimetric analysis. An intercalation model was then proposed to explain the mechanism. The results show that in Mt suspension, the interlayer adsorption is mainly responsible for the large adsorption amount of PCE. The improvement in clay tolerance of PCE in the presence of PEG is attributed to the preferential intercalation of PEG, which significantly hinders the intercalation of PCE. The result also suggests that those polymers with positive charge or considerably strong polarity might enhance the clay tolerance of the PCE system through the preferential intercalation. It also provides experience for practical application of PCE.
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Acknowledgments
We are grateful to the financial support of the National Natural Science Foundation of China (51408448) and Science and Technology Support of Hubei Province of China (2015BAA084) and the testing support of Materials Research and Testing Center of Wuhan University of Technology.
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Published In
Journal of Materials in Civil Engineering
Volume 29 • Issue 9 • September 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Oct 4, 2016
Accepted: Jan 31, 2017
Published online: May 16, 2017
Published in print: Sep 1, 2017
Discussion open until: Oct 16, 2017
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