Investigation the effect of bacteria and silica fume on physical and mechanical properties of normal, lightweight and high strength concrete.

The rapid advancement in technology and population growth have significantly increased the demand for specialized buildings, making the improvement of concrete quality essential. Traditionally, enhancing concrete strength involves increasing cement content, which not only escalates costs but also contributes to environmental pollution through greenhouse gas emissions. To address these challenges, alternative methods such as incorporating bacteria and silica fume into concrete have been investigated. Bacteria, particularly Bacillus megaterium, can enhance concrete by promoting calcite formation, which fills voids and improves compressive strength while reducing permeability. Similarly, silica fume increases concrete strength by producing additional calcium-silicate-hydrate (C-S-H) instead of calcium hydroxide (Ca(OH)۲). This study examined the effects of bacteria and silica fume on the physical and mechanical properties of concrete using ۵۴۰ samples, including ۴۵ different mixtures with two bacterial concentrations. The results indicated that adding bacteria to the concrete mix increased compressive strength by ۷% to ۲۳%. The inclusion of silica fume led to a strength increase of ۵% to ۲۳%. Furthermore, water absorption was reduced by ۳۲% to ۶۳% in samples with bacteria and by ۱% to ۱۵% in those with silica fume. The chloride ion penetration also decreased, with reductions ranging from ۵% to ۲۰% in samples containing bacteria and from ۰% to ۱۳% in those with silica fume. These findings suggest that the use of bacteria and silica fume in concrete can effectively enhance its mechanical properties and durability while mitigating the environmental impact associated with increased cement usage.

کلیدواژه ها:

Bacterial Concrete ، silica-fume concrete ، Concrete Compressive Strength ، Concrete Enhancement