Characterisation of healing agents for self-healing cementitious systems

Characterisation of healing agents for self-healing cementitious systems

Gardner, D.
Herbert, D.
Jayaprakash, M.
Jefferson, A.

2013-06-16

Recent developments in self-healing technology inspired by natural biological materials have the potential to dramatically improve the performance and durability of cementitious materials. These self-healing cementitious materials comprise artificial flow networks embedded within the cementitious matrix that upon damage release healing agents that are transported via capillary flow to macro-cracked and microcracked regions. However, the mechanisms of capillary flow in cementitious materials and the interactions between varying viscosity and surface tension are not well understood and there are few reported studies to date that have attempted to measure or simulate these for cementitious materials. This paper considers the flow characteristics of healing agents in macro-cracks formed as a result of material damage occurring during the early life of a structure and whose presence contributes to the deterioration processes that reduce the longevity of reinforced concrete structures. The ability to predict the capillary flow of healing agents within discrete cracks will further the development of efficient self-healing cementitious materials which will in turn deliver economic, environmental and social benefits, such as reduced maintenance and repair costs and reduced use of natural resources. This paper presents the results from an experimental investigation into the Hagen-Poiseuille (H-P) flow characteristics of one autonomic (adhesive based) and one autogenic (pozzolanic based) healing agent. Particular attention is given to the timeviscosity and time-surface tension relationships of the healing agents when in contact with mortar. Additional benchmark experiments are currently being undertaken for the capillary flow of the two healing agents between glass plates and concrete plates of varying compressive strength. These studies provide data to validate a numerical model developed by the research group, in which terms are added to allow for stickslip behaviour and frictional dissipation at the meniscus wall boundary. The initial results from these validations are promising and confirm the validity of the theoretical approach adopted.

healing agents
capillary flow
cementitious materials
self-healing

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Conference proceedings

conference paper

(c) 2013 Gardner, D.; Herbert, D.; Jayaprakash, M.; Jefferson, A.