The Hazards of Asbestos in Concrete and Cement
From the early 1900s through the mid-1980s, asbestos was a staple in many building materials as an accessible, readily available, and cheap material to add reinforcement, insulation, and fire resistance.
After the health risks linked to asbestos became known, various asbestos-containing materials were banned, but not asbestos concrete, considered low risk to the public and allowed in manufacturing and new construction. The risk of asbestos exposure is low when asbestos-containing construction products are undisturbed, but any damage can release toxic fibers into the immediate environment. It is the case of old concrete and goods made of asbestos-containing cement. Asbestos dust poses a high health threat to construction industry workers when proper precautions aren't taken.
Benefits and Risks of Asbestos in Concrete
Reinforcing concrete with the mineral's fibers added to its durability. It is a common practice with apparent benefits in the construction industry: it increases structural integrity. Generally, fiber reinforcement is used to:
- increase tensile strength
- control cracking from drying shrinkage
- lower the permeability of the concrete
- reduce water seepage
Usually, asbestos concrete consists of a mixture made primarily with chrysotile asbestos, also known as white asbestos, often called good asbestos in the industry. However, the mix had smaller amounts of the more dangerous crocidolite or blue asbestos. Besides the general benefits of fiber reinforcement, asbestos brought a few additional advantages:
- blends easily into concrete mixes
- it made concrete workable
- resists corrosion, leaving no corrosion stains on the surface
- it has a low friction grade, making it attractive for cement piping
- has a superior strength-for-weight ratio
The health risk of inhaling or ingesting airborne asbestos particles is the primary hazard of any asbestos product. In the past, construction workers and those in asbestos cement manufacturing bore the brunt of the health risks of asbestos concrete. Exposure through manufacturing is no longer an ongoing concern, but certain maneuvers that disturb asbestos concrete still represent exposure risk:
- chipping
- drilling
- pressure-washing
- demolition
- sanding
Although asbestos makes concrete and other products more durable, they will eventually deteriorate due to wear and tear. With about a 70-year lifespan, many asbestos cement products are beginning to deteriorate today. Anyone exposed to eroding or crumbling cement that was installed before the mid-1980s could be at risk, but the most at-risk occupations are:
- boilermakers
- bricklayers
- carpenters
- cement factory workers
- construction workers
- demolition workers
- flooring installers
- foundation installers
- masons
- military veterans
- pipefitters
- plumbers
- renovation contractors
- roofers
- shipyard workers
- siding installers
The biggest issue with asbestos concrete is that it can only be identified with professional testing. Since asbestos fibers are microscopic and encased in a hardened mix, they can't be identified with the naked eye. If you suspect your worksite may have asbestos concrete, you must have it tested by an accredited professional.
Asbestos in Concrete Today
Nowadays, asbestos concrete rarely occurs in new construction. Today's vast majority of asbestos cement was set in the late 1980s or earlier. However, most of these products are starting to show signs of advanced surface erosion and deterioration. It is particularly concerning for old asbestos cement piping, which was common in :
- sewage systems
- drainage pipes
- storm drainage systems.
Shingles and siding are also deteriorating due to normal weathering, so carefully monitoring for corrosion is necessary to prevent a public health threat. As wear and tear show signs in asbestos products in the coming decades, projects to rip out and replace old asbestos cement will remain ongoing and carry health risks for the workforce.