Physicochemical analysis of primers and liquid membranes as asbestos’ encapsulant

Abstract

Asbestos-containing materials pose significant health risks due to the potential dispersion of harmful fibers into the environment. This study presents a comprehensive physicochemical analysis of coatings, including primers and liquid membranes, designed to be applied on asbestos cement roofs, aiming to prevent the release of asbestos fibers and safeguard human health. Primers are normally used during the process of removing asbestos-containing panels to minimize the dispersion of fibers in the environment. By encapsulating the fibers on the surface, the primer helps to reduce the risk of fiber release during handling and removal. On the other hand, the primary goal of a liquid membrane is to encapsulate the asbestos fibers permanently, for long-term protection, preventing the potential health risks associated with asbestos exposure.To assess the reliability of primers and membranes is a matter of great importance especially for developing counties which have recently forbidden or are in the prohibition phase for the use of asbestos fibers. Two primers and two liquid membranes were investigated in a certified laboratory through a series of chemical and physical analysis. A primer was taken from commercial products in Colombia, a country that forbids asbestos but does not have legislation on these products, while two primers and a membrane were taken from a European country with high standards and decades of experience in the production of these materials to prevent asbestos exposure. The solid content, ash content, determination of primary solvents, thermogravimetry, infrared spectrum (FT-IR) of the polymer, infrared spectrum (FT-IR) of powders (fillers and pigments), and density were analyzed in the four products. Additionally, the membranes underwent testing for heat resistance, resistance to rain and freeze-thaw cycles, water impermeability, and accelerated aging (UVA 340, 1000 h). Furthermore, on membranes, adhesion capability (pull-off) was tested before and after heat-rain, freeze-thaw, UV ageing tests to ensure a durable bond between the coating and the asbestos surface.The results of the investigation revealed promising findings for both the primer and liquid membrane formulations. The primer demonstrated its potential applicability during the removal of asbestos panels, offering a preliminary safeguard against fiber dispersion. On the other hand, the liquid membranes exhibited excellent properties in encapsulating asbestos fibers effectively, providing long-term protection to the substrate. The Colombian membrane shown a calcium carbonate basis for the inorganic filler, with an almost pure acrylic polymer, while the second membrane shown a polymer styrene-acrylic matrix. This leads to less elasticity for the first membrane, and a possible exposure to acid rain attacks. Nevertheless, this chemical difference did not alter the results of the aging tests.