Crystallization waterproofing
Introduction
Concrete crystallization is a technological procedure used both in the manufacture of fresh concrete and in existing concrete structures, to make them waterproof and resistant to pressure water, generally up to 16 bars.
Basics
Under certain environmental situations, concrete is a very weak construction material. The different external and internal conditions end up affecting its stability definitively sooner or later. Thus, the cracks formed give way to the corrosive agents transported to the reinforcement and to the matrix of the concrete itself.
The crystallizing concrete additives have the unique and singular property of creating a dense and indissoluble crystalline capillary network in the pores of the wet concrete that definitively close the passage of water molecules through them. The water contained in the microcracks and capillaries of the concrete is transformed through a chemical reaction into crystals and this progressively makes the contained moisture disappear.
During the reaction with water, the aluminum and calcium ions contained in the concrete form indissoluble crystals that grow within the capillary system. As long as there is moisture in the concrete structure, they continue to grow through the crystalline network over and over again, almost indefinitely.
This process takes place, both under negative and positive water pressure, in such a way that the treated materials reach such a high density of crystals that liquid water is not able to penetrate them.
Harmful elements dissolved in water (chlorides or salts "Salt (chemistry)"), e.g. e.g.) they cannot therefore be transported into the concrete so it does not suffer any damage due to their harmful action. When crystallization ends, transforming all the contained moisture, the chemical process stops. With this system, carbonation of the concrete is also effectively avoided.
If, due to any type of cause or incident, a crack is created in the treated concrete and water enters, the crystallizing process “awakens” again and begins again.
Uses
In general, there are different uses in which active crystallization of permanent concrete is required. The support material for the crystallizing agent is cement, so in principle it can be said that this method is applicable to all concrete and cementitious materials that are in contact with moisture. Variants of the most common products are additives, mass waterproofing and different [mortars].