Michael J. Tate1 and Margaret L. Thomson2, Ph.D.

  1. Building Lime Sales Manager, Graymont Dolime (OH) Inc., Genoa, Ohio U.S.A 43430, 419-855-8336, fax 419-855-4602, e-mail mtate@graymont-oh.com
  2. Technical Manager, Building Construction, Chemical Lime Company, Henderson, Nevada U.S.A. 89015, 702-565-3833, fax 702-565-7473, e-mail margaret.thomson@chemicallime.com


Portland cement-Type S hydrated lime mortars are used extensively throughout the United States and Canada. Air entrained Type S hydrated lime may be used interchangeably with non-air entrained Type S hydrated lime in ASTM C 270 (Standard Specification for Mortar for Unit Masonry), but there is no preference toward either product where freeze-thaw conditions are prevalent. There appears, therefore, to be no perceived difference in freeze-thaw durability of air entrained or non-air entrained Portland cement-lime mortars in the field.

This study will report on the frost durability of three Type S proportion Portland cement-lime mortars (1 Portland cement:½ lime:4½ sand, by volume). Two of these mortars contain an air entrainment additive (8% and 11% measured air volume). The third mortar does not have an air entrainment additive. Plastic and hardened mortar properties are determined for each of the mix designs. Frost durability is determined using the unidirectional freeze-thaw test (BCRL Panel Freezing Test) and visual assessment.

Results indicate that non-air entrained Portland cement-lime mortars, as tested, are no more vulnerable to freeze-thaw damage than air entrained mortars. It is suggested that the well established resistance to moisture penetration resistance of Portland cement-lime mortars could account for this excellent performance.

Key words: Portland cement-lime mortar, freeze-thaw durability, unidirectional freeze-thaw testing, Type S hydrated lime, air content, masonry, Type S mortar