Comparison of resistance improvement to Aspergillus brasiliensis growth on recycled building materials by nano-metal impregnation and ozone treatment

Abstract

This study explores the potential of nanometal and ozone treatment to improve the Aspergillus brasiliensis resistance of recycled building materials (RBMs). RBMs include gypsum board (GB), waterproof gypsum board (WGB), calcium silicate board (CSB), and fiber cement board (FCB). The A. brasiliensis was inoculated on each sample, and their growth was visually evaluated according to ASTM G21-09. The results show that the effect of the treatment with nano-silver of 0.015 g/L and 0.03 g/L solution by impregnation was similar to that of the treatment with 60 ppb concentration of ozone for 4 hours: rating 3 on GB, rating 1 on WGB, rating 1 on CSB, and rating 1 on FCB. The antifungal effects of different building materials treated with different types and concentrations of nanometals or ozone are different. All the tested nanometals or ozone of the selected concentrations failed to provide complete protection against fungal growth on the four tested BMs. However, it is supposedly confirmed that the higher the nanometal concentration was, the longer the lag period until fungi growth began, and fewer fungi grew on the materials.