Mathematical Model for Predicting Stress-Strain Behaviour of Bacterial Concrete

Bacillus subtilus, a mineral precipitating microorganism, when introduced into concrete produces calcium carbonate crystals which seals the micro cracks and pores in the concrete. This process imparts high strength and durability to bacteria treated concrete along with enhancement in other mechanical properties. In order to study one such mechanical property, the stress-strain behavior of bacterial concrete, appropriate analytic stress-strain model is established that capture the real (observable) behavior. In this paper, an attempt is made to develop a mathematical model for predicting the stress-strain behaviour of bacteria induced high strength concrete. This research mainly aims at utilizing the best attributes of earlier models and proposes a new stress-strain model that can well represent the overall stress-strain behavior of high strength bacterial concrete mixes. After obtaining the stress-strain behavior of controlled and bacterial concrete experimentally, empirical equations are developed to represent uni-axial stress-strain behavior of controlled and bacterial concrete mixes. From these empirical equations, theoretical stresses for controlled and bacterial concrete are calculated and compared with experimental values. The proposed equations have shown good correlation with experimental values validating the mathematical model developed. The proposed empirical equations can be used as stress block in analyzing the flexural behavior of controlled and bacterial concrete.