Applies to mortar, in five types according to the properties of the constituent material, for use in structures constructed of masonry, and specified by proportions or by compressive strength. Requirements are included for the constituent materials, for storage, measuring and mixing, and for water retention. Provision is made for lime putty using either hydrated lime or quicklime, and reference is made to admixtures. Methods for the determination of chloride salts in fine aggregate and compressive strength of the mortar are set out in appendices.