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Avoiding autogenous shrinkage by in-situ crosslinking of hydrogels found in nature

par Snoeck, Didier ;Baertsoen, Thomas;De Belie, Nele
Référence fib Symposium, page (783-789)
Publication Publié, 2022-07-01

Article révisé par les pairs

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Résumé :

Autogenous shrinkage and subsequent shrinkage cracking in cementitious materials with a low water-binder ratio are major concerns, for example in tunnel elements and ground-retaining structures. This causes the need to include a significant amount of additional shrinkage reinforcements in the structural design. In addition, if cracking occurs, necessary repair works are exhaustive, costly, and sometimes infeasible due to inaccessibility. And if not done properly, the durability of the material may be compromised. In order to avoid autogenous shrinkage, internal curing may provide a solution and synthetic superabsorbent polymers (SAPs) are already used as such curing mechanism with promising results. However, the chemical backbone of the polymers is mostly not sustainable in terms of synthesizing the polymers. To solve this issue in a world where climate change is more prominent than ever, it is crucial to find alternative and more environmentally friendly materials. This research evaluates the potential of naturally occurring materials to function as hydrogels in order to reduce autogenous shrinkage. Not only cheap, these polymers may also be crosslinked in situ, requiring no need for crosslinking prior to application in a cementitious material. The research shows that the crosslinking in situ leads to an easy application, a controlled particle size and void formation, and to a complete mitigation of autogenous shrinkage with some observed expansion in the studied samples. This more sustainable approach opens the pathway of reducing the amount of shrinkage reinforcements needed, a reduction in overall costs and a more durable and sustainable material.