Impact of bioaerosol in building materials and its prevention using nano silica coating

Abstract

This study was aimed primarily to evaluate the impact of bioaerosol in building materials i.e. (Plain Cement Concrete and Fly Ash Concrete) and its prevention using nano silica coating. The first part of the work dealt with the test tube analysis (preliminary study) which is done to evaluate which fungus is more dominant against deterioration of building materials by using small pieces of concrete cube, where we infected the pieces of Plain Cement Concrete and Fly Ash Concrete by Aspergillus tamarii and Aspergillus niger and kept the setup in incubator for 1 month at 27℃ for growth of fungus and after 1 month we carried the visual analysis i.e. colour changes, chemical analysis i.e. pH change in media, physical tests i.e. weight loss etc. which showed the result that Aspergillus tamarii is more dominant against biodeterioration of building materials than Aspergillus niger. In the second part, concrete cubes of (Plain Cement Concrete and Fly Ash Concrete) (dimensions: 10 cm x 10 cm x 10 cm) were prepared and experimented in different set-ups namely control, biodeterioration (Aspergillus tamarii infected) and prevention (fungus infected nanocoated cubes). Analysis at intervals of 2 months and tests (visual, physical, and chemical) were done to evaluate the extension of the biodeterioration in the cubes, for six months. The visual analysis included colour changes, Stereo Microscopy and Scanning Electron Microscopy (SEM) which showed considerable change in the surface deterioration and fungal colonization of biodeteriorated cubes more than the nanocoated concrete cubes. The physical tests included weight loss which showed positive in all the concrete specimens and compressive strength which increased in nanocoated concrete cubes more than that of the biodeteriorated ones. The chemical analysis included pH change in media, Fourier Transform Infrared Spectroscopy (FTIR) and Energy Dispersive X-Ray Fluorescence Spectroscopy (EDXRF) which showed that leaching of calcium ions from the concrete in biodeteriorated cubes were higher than that of nanocoated cubes. Altogether the effectiveness of silicon oxide nanocoating against biodeterioration of Aspergillus tamarii was concluded to be positive.