Mortar Admixtures: Commercial Masonry

Mortar Admixtures for Commercial Masonry block, brick & stone work

Commercial masonry work uses different types of materials depending on the nature of the project. Some of the most common types of masonry construction materials include brick, stone, blocks, mortar, concrete, and more. Projects could also entail constructing facades for the fronts of buildings, walls, and other structures, while other types of masonry work contribute to structural construction. 

In addition to base materials, commercial masonry may use certain types of mortar admixtures for brick, block, and stone work to enhance specific properties. Knowing the different types of mortar admixtures may help you select the right option for your masonry work.

Mortar Admixture Types (ASTM)

The American Society for Testing and Materials (ASTM), or ASTM International, has developed a standard specification for masonry mortar admixtures. The specification, ASTM C1384-18e1, lists the various recognized types of admixtures used when mixing masonry mortars.

According to ASTM International, the following are the main types of mortar admixtures:

• Bond enhancers
• Workability enhancers
• Set accelerators
• Set retarders
• Water repellent

These admixtures work with mortar and masonry cement, along with other construction materials such as Portland cement, lime, and sand. Using the right admixtures in masonry mortar, you can experience numerous benefits such as reduced water absorption, reduced efflorescence, improved strength, and optimized workability.

Commercial Construction with Bricks

Type M mortar is popular for use in brickwork since it contains the most Portland cement content of all mortar types. These applications may also use lime mortar because of its unique advantages over cement mortar, including increased workability, less shrinkage, and better water retention. Cement-lime mortar is also ideal for brickwork as it offers more flexibility and gives more room for bricks to move while keeping the mortar from cracking. Brick walkways and other below-grade applications may also use Type S mortar.

Brick walls often use flush joints that allow for additional plastering and finishing. With joints flush to the brick wall, they tend to lend a more monolithic appearance to the final construction.

Commercial Construction with Stone

The type of mortar you would typically use for stone masonry work is Type N mortar, which consists of one part Portland cement, six parts sand, and one part lime. Masonry construction often uses this type of mortar for stone veneer and limestone or other soft stone masonry work. Type M mortar mix is also suitable for natural stone, as it provides strength similar to stone with a high amount of Portland cement content. 

The most common type of mortar joint used for stone is a standard raked mortar joint, which is normally around half an inch wide and half an inch “raked” or recessed from the stone’s face. The result is a more natural stone look.

Commercial Construction with Blocks

Like other masonry work, Type M, N, and S mortar cement is often used for work with concrete blocks. Type M and N are ideal for many walls and other facades, while Type S works for walkways, foundations, and retaining walls, among other structures. 

Cement block masonry work often uses beaded joints that lends a more historic appearance to block walls. Concrete blocks may also use overgrout mortar joints, which also give a historic look and function similar to flush mortar joints.

Select the Right Admixtures for Your Application

Depending on the type of masonry work you want to complete and the materials you’ll want to use, you might use Type M, N, or S mortar along with various mortar joint types. You can then determine what properties you need to choose the ideal mortar admixture, whether you need added strength, durability, workability, or other attributes. The perfect blend of materials will help complete any type of commercial masonry project using brick, block, or stone construction.