Assessment of microalgae-influenced biodeterioration of concrete structures

The aim of this study was to isolate microalga involved in the biodeterioration of concrete structures. The growth of algae was monitored between day 1 and 18 using a spectrophotometer (Spectronic 721 model) at varying pH (4.2 and 9.4). To identify the microalgae, aliquots of the isolates was placed on microscope slides and observed with the microscope using x40 Objective lens. Results revealed the highest growth to be between days 12 and 15 with 0.6 optical density, while the least growth was shown between 9 to 12 days. Microalgae isolated in the study include; Chlorella spp., Ulothrix spp., Xanthidium spp., Gleocystis spp., Nitzchia spp., Chlorodium spp., Oedogium spp., Synecoccus spp. and Chlorococcum. Chlorella showed the highest frequency of occurrence with 77.5% while Ulothrix spp. and Xanthidium spp. had the least frequency of 12.5% respectively. The presence of these organisms on concrete structure suggests they contribute to its biodeterioration. There is need therefore to prevent colonization of structures by coating concrete surfaces using paints, epoxies and polymers.Key words: Microalgae, Biodeterioration, Colonization and Concrete