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Biobased Spore Microcapsules for Asphalt Self-Healing

Erik Alpizar-Reyes Orcid Logo, José L. Concha, Francisco Martin-Martinez Orcid Logo, José Norambuena-Contreras

ACS Applied Materials & Interfaces, Volume: 14, Issue: 27, Pages: 31296 - 31311

Swansea University Author: Francisco Martin-Martinez Orcid Logo

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DOI (Published version): 10.1021/acsami.2c07301

Abstract

Asphalt pavements and bituminous composites are majorly damaged by bitumen aging and fatigue cracking by traffic load. To add, maintenance and reparation of asphalt pavements is expensive and also releases significant amounts of greenhouse gases. These issues can be mitigated by promoting asphalt se...

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Published in: ACS Applied Materials & Interfaces
ISSN: 1944-8244 1944-8252
Published: American Chemical Society (ACS) 2022
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URI: https://cronfa.swan.ac.uk/Record/cronfa60631
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Abstract: Asphalt pavements and bituminous composites are majorly damaged by bitumen aging and fatigue cracking by traffic load. To add, maintenance and reparation of asphalt pavements is expensive and also releases significant amounts of greenhouse gases. These issues can be mitigated by promoting asphalt self-healing mechanisms with encapsulated rejuvenators. The ability of the required microcapsules to be resilient against high temperatures, oxidation, and mechanical stress is essential to promote such self-healing behavior without compromising the field performance of the asphalt pavement. This work proposes, for the first time, the use of extremely resistant biobased spores for the encapsulation of recycled oil-based rejuvenators to produce more resilient self-healing pavements. Spore encapsulants were obtained from natural spores (Lycopodium clavatum) by applying different chemical treatments, which enabled the selection of the best morphologically intact and clean spore encapsulant. The physical, morphological, and physicochemical changes were examined using fluorescence images, ATR-FTIR, SEM, size distribution, XRD, TGA and DSC analyses. Sunflower oil was used as the encapsulated rejuvenator with an optimal sol colloidal mixture for sporopollenin–oil of 1:5 (gram-to-gram). Vacuum, passive, and centrifugal encapsulation techniques were tested for loading the rejuvenator inside the clean spores and for selecting the best encapsulation technology. The encapsulation efficiency and the profiles of the accelerated release of the rejuvenator from the loaded spores over time were studied, and these processes were visualized with optical and inverted fluorescence microscopy. Vacuum encapsulation was identified as the best loading technique with an encapsulation efficiency of 93.02 ± 3.71%. The rejuvenator was successfully encapsulated into the clean spores, as observed by optical and SEM morphologies. In agreement with the TGA and DSC, the microcapsules were stable up to 204 °C. Finally, a self-healing test was conducted through fluorescence tests to demonstrate how these biobased spore microcapsules completely heal a crack into an aged bitumen sample in 50 min.
Keywords: spores; sporopollenin; spore microcapsules; rejuvenators; biobased spore microcapsules; aged bitumen; bituminous materials; asphalt self-healing
College: Faculty of Science and Engineering
Funders: The authors thank the funding given by the National Research and Development Agency (ANID) through the Research Projects FONDECYT Postdoctoral no. 3200227 and FONDECYT Regular no. 1190027. The authors wish to thank the financial support given by the University of Bío-Bío for his internal PhD scholarship granted.
Issue: 27
Start Page: 31296
End Page: 31311