Hope for asbestos?
Previously celebrated as a miracle substance, now a feared carcinogenic substance - attitudes towards asbestos have changed drastically in recent years. Remediation measures are expensive and not without risk. A chemical company's report that it can convert asbestos into harmless silicates - without having to remove it from buildings - is just right. The American company W. R. Grace and Brookhaven National Laboratory in Upton announced at a joint press conference that a new chemical foam breaks down asbestos fibers into harmless silicates while maintaining fire retardancy.
Asbestos fibers are non-combustible, heat-resistant and thermally insulating and were therefore a popular building material in the past. However, some forms of asbestos are carcinogenic. As a result, over the past two decades, specialist contractors have been removing asbestos cladding from buildings and replacing it with safer fireproofing materials - a job that takes a long time, costs a lot of money and has allowed asbestos fibers to get into the respiratory tract.
The scientists therefore looked for a way to render the asbestos fibers harmless without having to rip them off the wall. They developed a foam of acids and fluoride ions that converts the fibers into an amorphous form that apparently protects against flames just as well.
(See also Asbestos: The Rise and Fall of a Miracle Material in Spectrum of Science 11/97, page 86)