Microfibres and hydrogels to promote autogenous healing in cementitious materials

Microfibres and hydrogels to promote autogenous healing in cementitious materials

Snoeck, D.
Dubruel, P.
De Belie, N.

2013-06-16

Cementitious materials are sensitive to crack formation and it would be beneficial if the material could stop the crack propagation, repair the damage and reach again the original liquid-tightness and/or strength. Therefore, a cementitious material with synthetic microfibres and superabsorbent polymers (SAPs) is proposed. Upon crack formation, the microfibres will become active and due to the bridging action, they will stop the opening of a crack, forcing the cementitious material to crack somewhere else. There, other fibres will become active. In this way, not one large crack, but several small healable cracks are formed. Further cement hydration and calcium carbonate precipitation will seal the crack if sufficient building blocks and water are present. The building blocks are available through the well-designed mixture with a low water-to-binder (W/B) ratio and water is available through the inclusion of SAPs. These polymers are able to extract moisture from the environment and to provide it to the cementitious matrix for autogenous healing. This healing will lead to the regain in mechanical properties. In this paper, the formed products are studied by means of optical and scanning electron microscopy. The healing efficiency was evaluated by reloading cracked and healed specimens and by comparing the new mechanical properties with the original properties. The crack width was limited to 50 ?m at 1% strain. While specimens without SAPs showed a regain of mechanical properties of 40-55% in wet/dry cycles, specimens with SAPs showed a total regain of 80-95%. Even in humid air, those specimens show partial healing of 35-55%. SAP B, a cross-linked potassium salt polyacrylate, showed better healing properties compared to SAP A, a copolymer of acrylamide and sodium acrylate. The smart material with SAP B thus is an excellent material to use in future building applications.

concrete
self-sealing
self-healing
superabsorbent polymers

http://resolver.tudelft.nl/uuid:07829c07-d77d-43b6-85cb-08a44b73f1a0

Conference proceedings

conference paper

(c) 2013 Snoeck, D.; Dubruel, P.; De Belie, N.