Polymeric microcapsules with switchable mechanical properties for self-healing concrete: Synthesis, characterisation and proof of concept

A. Kanellopoulos, P. Giannaros, D. W. Palmer, Maeve A. Kerr, A. Al-Tabbaa

Research output: Contribution to journalArticlepeer-review

59 Citations (Scopus)
35 Downloads (Pure)

Abstract

Microcapsules, with sodium silicate solution as core, were produced using complex coacervation in a double, oil-in-water-in oil, emulsion system. The shell material was a gelatin-acacia gum crosslinked coacervate and the produced microcapsules had diameters ranging from 300 to 700 μm. The shell material designed with switchable mechanical properties. When it is hydrated exhibits soft and 'rubbery' behaviour and, when dried, transitions to a stiff and 'glassy' material. The microcapsules survived drying and rehydrating cycles and preserved their structural integrity when exposed to highly alkaline solutions that mimic the pH environment of concrete. Microscopy revealed that the shell thickness of the microcapsules varies across their perimeter from 5 to 20 μm. Thermal analysis showed that the produced microcapsules were very stable up to 190 °C. Proof of concept investigation has demonstrated that the microcapsules successfully survive and function when exposed to a cement-based matrix. Observations showed that the microcapsules survive mixing with cement and rupture successfully upon crack formation releasing the encapsulated sodium silicate solution.

Original languageEnglish
Article number045025
Number of pages15
JournalSmart Materials and Structures
Volume26
Issue number4
DOIs
Publication statusPublished - 14 Mar 2017

Keywords

  • cement
  • concrete
  • construction materials
  • microcapsules
  • microencapsulation
  • self-healing
  • sodium silicate

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