Despite its indispensable use in today's world, concrete has a relatively short service life, mainly due to its tendency to crack. The formation of these defects weakens
the strength and load-bearing capacity of the structure and promotes the ingress
of water and other substances into it, which in turn causes the reinforced concrete
to corrode the steel structure. Self-healing of concrete is the ability of the building
material to repair the defects itself. Depending on the additions to the material,
self-healing mechanisms are divided into autogenous and autonomous. Autogenous
mechanisms take place in concrete without special additives, making it one of the
most affordable self-curing mechanisms. The disadvantages of this mechanism are
its unpredictability, its unreliability and its ability to fill only small cracks (up to
100 µm). Autogenous self-healing can be improved by various additives which limit
the dimensions of the cracks, provide water over a longer period and provide sites
for the formation of the products of the chemical reactions of autogenous healing.
However, this mechanism can only heal cracks up to 140 µm. In order to be able to
heal wider cracks and to improve the predictability of the mechanism, autonomous
healing has been developed based on the addition of special healing agents to the
concrete matrix. All chemical and biological self-healing methods fall under this
mechanism.
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