MATEC Web Conf.
Volume 289, 2019Concrete Solutions 2019 – 7th International Conference on Concrete Repair
|Number of page(s)||6|
|Published online||28 August 2019|
Prediction of the swelling capacity of salt-insensitive superabsorbent polymers in concrete by rheological measurements
Regional Business Segment Management Admixture Systems Europe, BASF Construction Solution GmbH, Trostberg, Germany
2 Application Technology - Construction Additives, BASF Construction Solution GmbH, Trostberg, Germany
3 Production, Chemist, BASF Construction Solution GmbH, Trostberg, Germany
A study on the macroscopic viscosity of a flowable, fine-grained high-strength mortar was conducted in order to estimate the swelling capacity of two salt-insensitive superabsorbent polymers (SAPs). In doing so, rotational rheometer measurements of the mortar modified with dry pre-mixed SAP were performed at several water-to-cement ratios (W/C), i.e. in the range 0.32 to 0.40. The swelling capacity of each SAP was estimated by correlating the fitted macroscopic viscosity vs. solid particle fraction curve with the curve of the plain mortar without addition of SAP, produced at the same W/C. The swelling capacities were found to yield 28 g pore water per g dry SAP (g/g) and 35 g/g, respectively. In addition to this new approach, two more practical relevant test methods were evaluated with respect to swelling capacity: first, comparative mortar spread tests, which were based on the use of the same fresh mortars but with less amount of superplasticizer, and second, tea bag tests with plain SAP immersed in an artificial pore solution. Only minor differences were found for the estimated swelling capacities. Hence the conclusion may be drawn that all three test methods are suitable for determining the swelling capacity of SAP in a cementitious environment.
Key words: macroscopic viscosity / salt-insensitive superabsorbent polymers / swelling capacity / tea bag test.
© The Authors, published by EDP Sciences, 2019
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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