Quality improvement techniques for recycled aggregates concrete incorporating fibers and Bacillus species bacteria – A review

Abstract

Recycling demolition waste as an aggregate may be a crucial key to improving sustainability in concrete construction with universal increases in construction waste. Specific methodology is nevertheless warranted for its practical application in the reclaiming of concrete construction and demolition (C&D) waste. Countries like India generate 23 million tons of recycled aggregates (RA), which may double in the next year. Currently, the construction industry is facing the problems of diminishing natural resources and growing demolition waste. The use of old concrete as an aggregate source has proved to be an attractive alternative in concrete production to natural aggregates. A detailed review of the effects of bacteria from Bacillus species and fibers to improve some chosen physico-mechanical properties of recycled aggregate concrete (RAC) is presented in this paper. Different fibers used in RAC improved their propagation limits and also improved their strength properties to certain limits. On the other hand, microbially induced calcite precipitation (MICP) improved the microstructural properties of RAC. The approach implemented a review of literature sources addressing the techniques of quality assurance and their impact on RA properties, including practical and environmental viability, water absorption, and compressive strength.