Roofing granules with additive of copper-zinc powder having biocidal properties

Introduction. In the world practice, ceramic coated roofing granules with various biocidal (algicidal) additives are used to prevent discoloration of asphalt roofing shingle. The paper propose the application of the selective dissolution of brass process to accelerate the algicidal effect of surface mineral granules. The authors show that incorporating of brass pigment in the color coat of roofing granules provides the desired degree of algae resistance over an extended period of time. Materials and methods. The brass pigment powder was taken as an algicidal additive. Algae resistant granules with the brass pigment were made in Stroymineral plant. Standard AR granules from North America market were taken as a control sample. Algicidal effect was measured by comparison of control sample and manufactured algae retardant granules performance in the 4 weeks quantitative spectrophotometric chlorophyll test. Measurement of an optical density of the liquid culture solution were made to determine the algae growth rates. The measurement was performed in the laboratory for the development of innovative medicines and biotechnologies in MIPT University. Results. The results show that manufactured algae retardant granules displayed level of the algicidal activity which is equal to control sample during the research. It was found that the highest algicidal activity was shown by products manufactured using finely dispersed copper-zinc alloy powder with a zinc content between 15-30 %. Conclusions. The manufactured granules with brass pigment in the color coating reveal ability to inhibit the algae growth.