A method of delivering polymeric microspheres to protect a cementitious composition, such as concrete, from freeze-thaw damage which comprises the addition of a dry blend of mineral powder and dry-expanded polymeric microspheres to cementitious compositions is described. The polymeric microspheres form annulus voids in the cementitious matrix by undergoing thermal contraction as the ambient temperature drops. The annulus voids act as entrained air voids to provide spaces for ice crystals to grow, thereby greatly reducing or eliminating the risk of cracking of the cementitious composition during freezing and thawing.