Incorporating color into mortar adds a whole new dimension to masonry. After all, mortar joints can account for as much as 20% of the surface area of brick, block or stone walls.
Colored mortars create another level of visual interest to the units they bond together, further expanding the already impressive array of architectural treatments available with masonry.
But colored mortars also make new demands on materials and workmanship. Long-lasting color that stands up to weather and wear requires precise proportioning and mixing. Uniform color throughout the project demands consistency. And ultimately, colored mortar must have the same performance properties as its grey counterpart: strength, durability and workability.
Proportioned and packaged under laboratory-controlled conditions, Lehigh colored masonry cements meet these demands by simplifying mortar mixing and ensuring consistent results from batch to batch, project to project.
The key is one-bag batching. Lehigh blends precise amounts of cement, pigments and other ingredients to help eliminate errors and inconsistencies when mixing mortar at the job site. There are fewer ingredients to deal with and less potential for variation. Workers just add sand and water.
At their simplest, masonry cements are a mixture of portland or blended cement and a plasticizing material, such as hydrated lime, which retains water and lends "workability" to the mortar mix – a measure of ease of use for masons. Other components enhance key properties, such as setting time, durability, strength, water resistance and color.
Pigments added to the masonry determine the color of the resulting mortar. Other materials, such as sand and cement, are also factors in determining in shade and hue. Workmanship comes into play, too, since tooling the joint affects both color and texture.
Colored masonry cement is premixed with pigments to offer a wide range of color. Because they are produced under highly controlled conditions, colored masonry cements ensure consistent color throughout the project. Lehigh's high-quality pigments produce colorfast mortar that resists fading from ultraviolet rays and weathering.
The iron oxides used in mortar are compatible with cement and provide color stability in the finished mortar joint. Pigments should conform to American Society for Testing and Materials (ASTM) C979, Specification for Pigments for Integrally Colored Concrete.
Masonry cement Types N, S and M are covered by ASTM C91, Standard Specification for Masonry Cements.
Mortar must conform to ASTM C270, Standard Specification for Mortar for Unit Masonry.
NCMA Solutions Center,TEK documents, building codes and specifications
ASTM C91, Standard Specification for Masonry Cements
ASTM C270, Standard Specification for Mortar for Unit Masonry
The Brick Industry Association