Freeze thaw durability admixtures are used in concrete where extreme seasonal temperature differences are common. A freeze thaw cycle is characterized by water absorption into the concrete. The water freezes resulting in ice expansion, at pressures exceeding 114,000 psi, which destroys the concrete in a localized area. As this ice melts, a larger void is left behind, where the cycle can repeat itself ultimately resulting in the complete failure of the concrete.
Freeze thaw durability admixtures encompass the performance properties of air entraining admixtures and water repellent admixtures. The water repellent component attempts to prevent diffusion of the water into the concrete, so that ice formation cannot occur with the concrete structure. The micro bubble formation provided by air entrainment admixtures provides a void where, in theory, if water penetrates the concrete, ice can form, without destroying the concrete.