What are masonry cements composed of and what types are there?
Masonry cements are hydraulic cements designed for use in mortar for masonry construction. They are composed of one or more of the following: Portland cement, Portland cement – pozzolan cement, Portland blast – furnace slag cement, hydraulic lime, and natural cement. In addition, usually contain materials such as hydrated lime, limestone, chalk, calcareous shell, talc, slag, or clay.
Materials are selected for their ability to impart workability, plasticity, and water retention to masonry mortars. Masonry cements meet the requirements of ASTM C-91, which classifies masonry cements as Type N, Type S, and Type M. A brief description of each type follows;
Type N masonry cement is used in ASTM C-270 Type N and Type O mortars. It may also be used with Portland or blended cements to produce Type S and Type M mortars.
Type S masonry cement is used in ASTM C-270 Type S mortar. It may also be used with portland or blended cements to produce Type M mortar.
Type M masonry cement is used in ASTM C-270 Type M mortar without the addition of other cements or hydrated lime. The workability, strength, and color of masonry cements stay at a uniform level because of manufacturing controls. In addition to mortar for masonry
construction, masonry cements are used for parging and plaster (stucco); they must never be used for making concrete.