EXPERIMENTAL STUDY ON CORROSION OF REINFORCEMENT IN BACTERIAL CONCRETE

摘要

Propagation of micro cracks, leading to exposure to water and oxygen and thus causing corrosion, is the main cause of structural failure. Bio-mineralisation of calcium carbonate has been proposed as a sustainable method to remediate cracks in building materials, thereby increasing the durability of steel reinforced concrete structures. In this paper, an attempt has been made to first find the optimum concentration of bacterial cells to be incorporated in concrete. Based on the state-of-the-art information available in the literature three different bacterial samples are considered in concentrations of 10~4,10~5 and 10~6 cells/ml of mixing water. 10% of the mixing water are replaced by the bacterial sample. The bacteria considered are Bacillus megaterium, Bacillus subtitles and Pseudomonas aerugonisa and the optimum concentration is found to be 10~4, 10~5 and 10~5 cells/ml, respectively based on compressive strength results. The maximum increase in strength was observed for the above concluded concentrations. Water absorption test showed reduction in value which confirms the filling of pores. Accelerated corrosion is carried out by impressed current technique in RC beams with optimum concentration of each bacterium. The degree of induced corrosion is calculated by galvanostatic method. Finally the results are compared with the corrosion results of control specimens without bacteria. Based on the results, effectiveness of the bacteria in saline environment is studied.