We report here the development of a method for the
chemical digestion of chrysotile asbestos in asbestos-containing fireproofing to levels lower than the regulatory
threshold. The resulting fireproofing, no longer defined
as asbestos-containing, can remain in place with properties
intact. In the process, chrysotile fibers are digested
without generating excessive gaseous byproducts, and
the foam-based delivery system essentially eliminates release
of airborne fibers. New X-ray diffraction methods quantified
chrysotile levels with far greater precision than standard
optical microscopic methods. Full-scale field testing confirmed
the laboratory phase of the project. Fire testing of the
treated fireproofing showed that the treated material functions
as well as the original fireproofing.
The use of polymer impregnation as a means of upgrading the physical and mechanical properties of natural aggregates was evaluated in a series of tests performed using four aggregates of varying quality. The strength of concrete cast with polymer impregnated coarse aggregate was also tested. Two monomer systems were used in the investigation, a methyl methacrylate-based system and a styrene-based system.
In general, significant improvements in the physical and mechanical properties of each of the four aggregates resulted from polymer impregnation. The strength of concrete cast with impregnated aggregates varied, being increased in some cases and decreased in others.
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