Biological Durability of Bamboo Bio-Concretes

Studies on bio-based building materials are promising due to their insulating characteristics, low density and good hygrothermal performance. However, range of factors can influence its durability, including biological processes. For that reason, this study investigates the susceptibility to the growth of microorganisms in bamboo bio-concretes (BBC) with different finishes: (i) natural samples and (ii) samples waterproofed. The bio-concretes, after curing until 28 days (23 ℃; 55% RH), were sterilized for 24 h in an oven (100 ℃) and the hydrogenion potential (pH) determined. Subsequently, the samples were sprayed with suspensions of conidia of the fungus Aspergillus niger (IOC 0207) and a control suspension without fungi. After, the bio-concretes were conditioned in two controlled conditions of temperature (T) and relative humidity (RH), simulating environments of possible uses: (1) without water blade (23 ± 2 ℃; 74 ± 2% RH) and (2) with water blade (23 ± 2 ℃; 98 ± 2% RH). Biological durability was evaluated according to visual analyses by photographs and optical microscopy at 0, 7, 14, and 28 days. For conditioning 1, it was not possible to observe fungal proliferation on the surfaces of any sample during the test. For conditioning 2, the high RH environment and the presence of the water layer caused a color change, saturation and growth of microorganisms. The results show that the higher the RH, the greater the susceptibility to the growth of microorganisms and changes in appearance. Despite this type of study being introductory, bio-concrete is a promising material, with potential to be used in civil construction, showing durability to the growth of the fungus A. niger.