Optimisation of compressive strength of foamed concrete with a novel Aspergillus iizukae EAN605 fungus

The production of concrete by incorporating a microorganism has emerged as a promising research area, offering potential benefits such as reduce carbon footprint, enhance durability and increased strength. The present study reported for the first time using a fungal strain (Aspergillus iizukae EAN605) in biocementation. The study aims to investigate the effectiveness of incorporating Aspergillus iizukae EAN 605 into foam concrete to improve its performance, particularly its strength. The study employs the response surface methodology (RSM) to explore the relationship between density, microorganism concentration and water /cement ratio (w/c) and their effects on compressive strength. Through a series of experiments,the highest recorded compressive strength was achieved with a density of 1800 kg/m³, w/c ratio of 0.5, and Aspergillus iizukae EAN605 concentration of 0.5 g/l, resulting in a remarkable 37.5 % increase compared to foam concrete (FC). The variables of density, A. iizukae EAN 605 and their interaction density*fungi (D*F) significantly impacted compressive strength, with p-values of 0.000, 0.016, and 0.010, respectively.X-ray diffraction (XRD) analysis was employed to identify the crystalline composition of the precipitates formed on the fungal hyphae, providing insights into the mineralogical transformations occurring during the biocementation process. Additionally, scanning electron microscope (SEM) imaging was utilised to visualise the morphology and distribution of the calcite crystals, further supporting the evidence of fungal-mediated mineral precipitation in foam concrete. The findings of this study hold significant implications for the concrete industry, as the incorporation of Aspergillus iizukae EAN605 in foam concrete offers a sustainable solution to enhance compressive strength and contribute to environmental friendly construction practices. This study provides valuable insights for future research and practical applications in the field of bio-foamed concrete (B-FC).