Abstract
Self-healing concrete has emerged as one of the prospective materials to be used in future constructions, substituting conventional concrete with the view of extending the service life of the structures. As a proof of concept, over the last several years, many studies have been executed on the effectiveness of the addition of self-healing agents on crack sealing and healing in mortar, while studies on the concrete level are still rather limited. In most cases, mix designs were not optimized regarding the properties of the fresh concrete mixture, properties of the hardened concrete and self-healing efficiency, meaning that the healing agent was just added on top of the normal mix (no adaptations of the concrete mix design for the introduction of healing agents). A comprehensive review has been conducted on the concrete mix design and the impact of healing agents (e.g., crystalline admixtures, bacteria, polymers and minerals, of which some are encapsulated in microcapsules or macrocapsules) on the properties of fresh and hardened concrete. Eventually, the remaining research gaps in knowledge are identified.
Highlights
Concrete is one of the most consumed materials all over the world and it is regarded as an essential construction material in the global construction and infrastructure sector.The ability of concrete to withstand high compressive stresses contributes to its high loadbearing capacity
The main strategies of incorporating healing agent with or without capsules into the self-healing concrete mixes, as described in Figure 6; Effect of addition of healing agents on the properties of fresh and hardened concrete before healing; Brief evaluation of self-healing phenomenon in the cracked concrete after healing (Note: the term of healing efficiency/ratio refers to the crack width reduction or crack closure by microscopic investigation, while the sealing efficiency/ratio is determined by permeability test)
This paper explores three prospective self-healing materials including Crystalline admixture (CA), bacteria and encapsulated healing agents that can be used for repairing the cracks and improving the self-healing efficiency of concrete
Summary
Concrete is one of the most consumed materials all over the world and it is regarded as an essential construction material in the global construction and infrastructure sector. The properties of the fresh concrete mixture as well as the mechanical strengths were in most cases not evaluated due to the reason that the utilization of capsules focused solely on the quantification of the self-healing capacity. There have been many publications reporting the feasibility of different healing agents in the application of cementitious mortars, while very limited publications have reported on upscaling to the concrete level. It remains rather unclear on how the results observed in the mortars will be transferrable to the concrete. The self-healing properties of the concrete will be discussed concisely
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