Crystalline-based systems typically come in a dry, powdered form and are hydrophilic in nature. Unlike their hydrophobic counterparts, crystalline systems actually use available water to grow crystals inside concrete, effectively closing off pathways for moisture that can damage concrete. They block water from any direction because the concrete itself becomes the water barrier.
In contrast to water repellents, crystalline technologies enable self-sealing. The admixture is a blend of cementitious and proprietary chemicals that actually work with the available water in concrete to form insoluble crystals. These needle-like crystals grow until all pores are blocked and no water can penetrate the concrete. The crystalline formula can allow concrete to self-seal hairline cracks up to 0.5 mm (0.02 in.), even years after the original construction.