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Sealing of cracks in cement using microencapsulated sodium silicate

Published version
Peer-reviewed

Repository DOI


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Authors

Giannaros, P 

Abstract

Cement-based materials possess inherent autogenous self-healing capability allowing them to seal, and potentially heal, microcracks. This can be improved through the addition of microencapsulated healing agents for autonomic self-healing. The fundamental principle of this self-healing mechanism is that when cracks propagate in the cementitious matrix, they rupture the dispersed capsules and their content (cargo material) is released into the crack volume. Various healing agents have been explored in the literature for their efficacy to recover mechanical and durability properties in cementitious materials. In these materials, the healing agents are most commonly encapsulated in macrocontainers (e.g. glass tubes or capsules) and placed into the material. In this work, microencapsulated sodium silicate in both liquid and solid form was added to cement specimens. Sodium silicate reacts with the calcium hydroxide in hydrated cement paste to form calcium-silicate-hydrate gel that fills cracks. The effect of microcapsule addition on rheological and mechanical properties of cement is reported. It is observed that microcapsule addition inhibits compressive strength development in cement and this is observed through a plateau in strength between 28- and 56-days. The improvement in crack-sealing for microcapsule-containing specimens is quantified through sorptivity measurements over a 28-day healing period. After just 7 days, the addition of 4% microcapsules resulted in a reduction in sorptivity of up to 45% when compared to specimens without any microcapsule addition. A qualitative description of the reaction between the cargo material and the cementitious matrix is also provided using X-ray diffraction (XRD) analysis.

Description

Keywords

self-healing, microencapsulation, sodium silicate, autonomic

Journal Title

Smart Materials and Structures

Conference Name

Journal ISSN

0964-1726
1361-665X

Volume Title

25

Publisher

IOP Publishing
Sponsorship
Engineering and Physical Sciences Research Council (EP/K026631/1)
Financial support from the Engineering and Physical Sciences Research Council (EPSRC) for the PhD studentship is gratefully acknowledged. Support from the EPSRC Materials for Life (M4L) project (EP/K026631/1) is also gratefully acknowledged. Additional data related to this publication is available at the University of Cambridge’s institutional data repository here: https://www.repository.cam.ac.uk/handle/1810/253547.