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Applications and life cycle assessment of shape memory polyethylene terephthalate in concrete for crack closure

Maddalena, Riccardo, Sweeney, John, Winkles, Jack, Tuinea-Bobe, Cristina, Balzano, Brunella, Thompson, Glen, Arena, Noemi and Jefferson, Tony 2022. Applications and life cycle assessment of shape memory polyethylene terephthalate in concrete for crack closure. Polymers 14 (5) , 933. 10.3390/polym14050933

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Abstract

Shape memory polymer (SMP) products have been developed for application as crack closure devices in concrete. They have been made from PET in the form of both fibres and hollow tubes. Here, manufacturing methods using die-drawing and mandrel-drawing to induce shape memory are reported. The fibre-based devices are incorporated into concrete and, upon triggering, exert shrinkage restraint forces that close cracks in the concrete. The evolution of shrinkage restraint force in the fibres as manufactured was measured as a function of temperature, showing stresses in excess of 35 MPa. Tendons consisting of fibre bundles are incorporated into concreate beams subjected to controlled cracking. When activated, the tendons reduce the crack widths by 80%. The same fibres are used to produce another class of device known as knotted fibres, which have knotted ends that act as anchor points when they incorporated directly into concrete. Upon activation within the cracked concrete, these devices are shown to completely close cracks. The tubes are used to enclose and restrain prestressed Kevlar fibres. When the tubes are triggered, they shrink and release the prestress force in the Kevlar, which is transferred to the surrounding concrete in the form of a compressive force, thereby closing cracks. The Kevlar fibres also provide substantial reinforcement after activation. The devices are shown to be able to partially and fully close cracks that have been opened to 0.3 mm and achieve post-activation flexural strengths comparable to those of conventional reinforced and prestressed structural elements. Finally, a preliminary life cycle assessment study was used to assess the carbon footprint a nominal unit of concrete made with SMPs fibres compared to conventional concrete.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Engineering
Additional Information: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Publisher: MDPI
ISSN: 2073-4360
Date of First Compliant Deposit: 29 April 2022
Date of Acceptance: 21 February 2022
Last Modified: 30 Apr 2022 16:15
URI: https://orca.cardiff.ac.uk/id/eprint/149365

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