Journal
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
Volume 104, Issue 7, Pages 3603-3618Publisher
WILEY
DOI: 10.1111/jace.17730
Keywords
H-1 NMR; absorption and desorption; internal curing; superabsorbent polymer; supplementary cementitious materials
Categories
Funding
- Ministry of Science and Technology, China [2018YFC0705400]
- Hunan Provincial Science and Technology Department [2020RC2034]
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The study demonstrates that internal curing with superabsorbent polymer (SAP) is effective in mitigating autogenous shrinkage of cement-based materials with low water-to-cement ratio. The absorption and desorption kinetics of SAP in blended cement pastes play a dominant role in controlling autogenous shrinkage. Different desorption behaviors are observed in binary and ternary cement pastes, primarily due to changes in osmotic pressure triggered by the acceleration of cement hydration by silica fume.
Internal curing by superabsorbent polymer (SAP) is an effective method to mitigate the autogenous shrinkage of cement-based materials with low water-to-cement ratio (w/c). In this study, the water absorption/desorption kinetics of SAP were studied quantitatively in blended cement pastes with ultra-low w/c. An absorption process at a rate of 0 to 6 g/(g h) was calculated at early ages. After that, SAPs showed mainly two distinct water desorption behaviors with a rate of 0 to 1.1 g/(g h), which was mainly governed by the osmotic pressure and capillary pressure triggered by the drop of internal relative humidity (IRH). The size and amount of SAP played a predominant role in controlling its absorption and desorption kinetics in the cement paste. Compared with ordinary Portland cement, a different desorption process with a higher release rate was noticed in binary and ternary cement pastes, primarily due to the changes in osmotic pressure resulting from the acceleration of cement hydration by silica fume at early ages. Overall, the mitigation of autogenous shrinkage is found to be highly dependent on SAP's absorption and desorption kinetics.
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