Valuation of characteristics strength by utilizing Construction and Demolition (C&D) waste as Recycled Aggregates (RA) in concrete

Concrete can be successfully made with demolition waste with up to 35% of substitution for coarse aggregates. To improve the performance of demolition waste concrete, microorganisms are applied over the concrete during the casting stage. This investigative research project explores the study of partial substitution of coarse aggregates with varying percentages of demolition waste aggregate (0%, 25%, 50%, 75% and 100%). Bacillus subtilis (1%, 2%, and 3%) by the weight of cement is mixed with water and added to green concrete to accelerate the performance. Various mechanical properties of all concrete specimens are studied with and without bacterial action to determine the optimal bio-mineralization percentage of augmentation which is determined as 20% with respect to conventional Concrete. Three beams are cast with optimum percentages of demolition waste and selected microorganism. The flexural behavior of the beams is discussed based on the load–deflection, stress and strain patterns. The experimental results are validated with the use of the Finite element Software Abaqus (Student version) with respect to simulation of mid-span deflection and its value for the beam with 25% demolition waste and 2% bacteria is found to be 0.49 mm and the corresponding value in Abaqus is 0.477 mm. The maximum value of mid-span deflection for the beam with 50% demolition waste and 2% bacteria is found to be 0.47 mm and the corresponding value in Abaqus is 0.432 mm.