Water repellent admixtures are designed to provide integral water repellency to concrete by affecting the capillary action of water into or out of the concrete.  Water diffuses into and out of concrete through micro voids and canals, typically found at the cement aggregate interface.  Water repellent admixtures can perform as static pore pluggers, creating a more difficult pathway for water migration, or can perform as reactive chemicals, forming “insitu” hydrophobic materials that not only plug pores, but also chemically repel water from cement surfaces.