Asbestos in Materials Such as Cinder Blocks, Mortar, and Bricks
Renowned for its insulating, heat resistance, and strengthening properties, asbestos was commonly used within a range of different construction materials, including bricks and cladding products for both exterior and interior applications.
It's important to note that asbestos is only a health risk in friable or dust-like form, allowing its microscopic fibers to become airborne. Once released, asbestos fibers are difficult to detect and they can remain suspended in the air for a long period of time. Homeowners are thus exposed not only at the time and place of release, but long after the release and far from its source. The majority of non-friable, hard-bonded asbestos-containing products and materials are safe to be around until they start to deteriorate, or are cut drilled, sanded, or scraped.
Asbestos Used in Brick Manufacturing and the Bricklaying Process
Before 1980, asbestos was used in brick manufacturing because it added immense tensile strength to materials.
Cinder blocks are hollow cylindrical or rectangular-shaped structures that find use in construction sites. Residential constructions built before 1900 containing cinder blocks were made with asbestos. Masonry Cement refers to a specific type of cement that contained asbestos as reinforcement, for preventing cracking in the finished product. This is the bonding agent used between cinder blocks and bricks. Prior to the public being aware of the dangers associated with the exposure to asbestos, the "miraculous" mineral was a common ingredient in masonry cement with asbestos being up to 10% of the masonry cement mix. The highly versatile material was cheap, easy to use, and provided a great deal of tensile strength and heat resistance to the finished product. W. R. Grace and Johns-Manville Corporation had a wide-ranging line of masonry fill which is practically insulation poured into cinderblock walls to increase the insulation value.
Mortar is an integral part of brickwork - it is essentially the glue used to bind bricks and other masonry units together when these materials are used for wall construction.
Mortar manufacturers were looking for a material that would possess high durability, would have insulating capability and would be naturally resistant to fire and heat. Until the 1980s, asbestos made up 90% of the mortar mixes in the United States. Builders preferred having it in the mix and used it when constructed private homes because it was cheaper and significantly stronger than cement-based mortars.
The following mortar products were known to contain asbestos:
- H.K. Porter Bonding Mortar Ho. 20
- National Gypsum Gold Bond Mortar Mix
- United States Gypsum Pyrobar Mortar Mix
Bricks - In the first half of the 20th century, chrysotile and amphibole asbestos were pulverized and included in brickwork mortar to increase the final product's strength and prevent fire and water damage.
Be mindful of the lining of chimneys and furnaces, as asbestos bricks were extremely popular and useful for fire resistance.
Other areas where you may find asbestos-containing bricks and mortar:
- Masonry walls
- Structural walls
- Facades, fences
- Balconies, verandahs
- Outbuildings - wall cladding
- Concealed spaces or cavities in external and/or internal wall
Asbestos in Imitation Brick Cladding - Imitation brick cladding was used as internal and external decoration, most commonly attached to asbestos-containing cement sheeting. Faux brick cladding became a popular renovation alternative in the 1930s when the Mastic Corporation began marketing InselBrick, asphalt-based faux brick siding panels, commonly used for covering the deteriorated exterior walls of older homes. Asbestos-cement panel with faux brick and mortar facing was popular due to its ease of installation and low cost; sheets did not need to be painted and were considered to be fireproof.
How Do I Know If Materials Such as Cinder Blocks, Mortar, and Bricks Contain Asbestos?
In order to identify possible asbestos materials, check the product name on the manufacturer label, and do a web search to find out it contains asbestos. The absence of such a label does not mean the material is asbestos-free.
Asbestos-based brick products and manufactures:
- GAF/Ruberoid: Brick-Strip Paper, Hearth-Glow Brick
- General Refractories Company (Grefco): Steelklad Dibond Firebrick
- Harbison-Walker Refractories Company: Metalkase Firebrick
- Dresser Industries, Inc.: Metalkase Firebrick; Nucon Firebrick
- Sherwin-Williams Paint Company: Brick and Stucco Buff
Check periodically for tears, abrasions, or water damage, if you think your home may have asbestos. As time goes by, mortar can break, and as it is exposed to the weather, it can fall apart. If you discover damaged building materials, limit access to the area, and do not touch or disturb it.