How do hydrogels have a positive impact contaminant migration through the concrete?
Permeability plays a critical role in influencing the service-life of a concrete structure. It controls the rate of flow of water and contaminants into-, out of-, and through-the concrete; which in turn is related to most forms of concrete deterioration such as carbonation, chloride attack, corrosion of rebar, freeze/thaw, and other forms of chemical and physical attack. These deterioration forms all require moisture migration. Therefore, permeability and moisture movement should be a factor of interest to architects, engineers, and contractors a-like.
A hydrogel is any gel in which the liquid component is water; or more specifically a microstructure that is hydrophilic. Hydrogels are a network of polymer chains that attract water (hydrophilic), and they come in different forms.
During the early curing phases, the hydrogels release a portion of water for the hydration process to help bridge concrete cracks and stabilize concrete corrosion mechanisms, which in a standard concrete contributes to later age cracking and premature failure.
Hydrogels can be an addition of a micro- and nano-based technologies that lead to hydrogel development in the concrete composite. The permeation of the hydrogel into the concrete composite is based on a series of mechanical and chemical processes.
From time zero when the hydrogel-technologies is sprayed onto the damaged concrete, the technology combines with the pore water solution in the concrete cracks and pores.
The pore water solution contains soluble alkalis and chlorides that initiate the rejuvenation process.
After time zero of spraying the hydrogel-technology on the concrete, the technology immobilizes and consumes the soluble alkalis to create a branching gel that bridges and fortifies concrete cracks and pores at the surface and into the body on the concrete where deterioration occurs.
Over time, these branched chains go through polymerization process and mature into a toughened building block of concrete strength.
This mature gel hardens to the point that it has a strength greater than or equal to the parent concrete binding material.
Ultimately, the hydrogel-technology uses the cracked concrete as a pathway for technology transport and a means to rejuvenate and densify the hardened backbone of concrete, ultimately making the damaged and deteriorated concrete stronger to last longer.