• Asbestos was used as fiber reinforcement in concrete.

    Credit: Mesothelioma Center

    Asbestos was used as fiber reinforcement in concrete.

Question: I have a job that entrails demolition at a factory building from 1935. The issue came up of whether we needed to worry about asbestos in the concrete or in some of the adhesives used for the flooring. There’s some old cement plaster on the exterior also. Is asbestos an issue for any of this?

A: While asbestos was once used in a number of industrial products as an insulator, it was also used in concrete mixtures to reduce cracking.

Jamie Farny at the Portland Cement Association (PCA) says, “Asbestos fibers were used in some concrete products in the past.” PCA’s book, Fiber Reinforced Concrete, states that it was the predominant form of fiber-cement composite when it was developed in the early 1900s. Products mentioned are flat and corrugated sheets, pressure pipes, and fire-resistant boards. The asbestos fibers were used for typical fiber benefits, although some testing indicated that they didn’t actually add much improvement. They are fire resistant and may have provided some benefit in this respect. Asbestos fibers may have been added to plasters or mortars, too.

Faith Franz, content writer for the Mesothelioma Center, says, “Concrete precasters added asbestos to products to make them less permeable and less likely to crack. Asbestos was considered a good fiber reinforcement since it was inexpensive, readily available, and easily blended into the mix.” When construction workers encountered asbestos-reinforced concrete on the roof of a government building, the project was halted until the roofing and soft concrete layer were removed. The concrete was found to contain between 2% and 10% asbestos by weight, and the construction company was required to comply with OSHA methods for removal. Franz notes that a similar process should be taken with any project that involves asbestos concrete.

Spotting asbestos in concrete products can be difficult. Since the fibers were evenly distributed throughout the concrete mixture and are now set in the hardened matrix, they cannot be seen with the naked eye. Unlike tiles or wallboard that may show wispy asbestos fibers as they disintegrate, concrete products do not show asbestos when broken. Professional testing should be conducted to confirm the presence (or absence) of asbestos before any construction is performed on potentially asbestos-contaminated concrete.

When renovations to an older building require the removal of asbestos-containing concrete, workers face increased risks of inhaling or ingesting the fibers. Although asbestos fibers are sealed within the matrix, chipping or otherwise tearing out asbestos-containing concrete could release the fibers into the air. If asbestos becomes airborne (especially in enclosed construction sites), workers face an elevated risk of developing asbestos-related diseases. If a concrete item is found to contain asbestos, any construction that has the potential to release fibers into the air must be performed in adherence with the Occupational Safety and Health Construction Standard 29 CFR 1926.1101(g). For more information on asbestos and its dangers, go to www.asbestos.com.

This answer was provided by Jamie Farny of the Portland Cement Association and Faith Franz, content writer for the Mesothelioma Center.