Application potentials of conch shell powder as a bacterial carrier for enhancing the Micro-Mechanical performance of biogenic gypsum plaster

Abstract

Microbial-induced calcite precipitation (MICP) is a relatively novel technology that can improve the strength and durability of gypsum plasters. This present study seeks to explore the application potential of three different bacterial species (Bacillus subtilis, Bacillus sphaericus, and Sporosarcina pasteurii) on the mechanical strength, durability, and microstructure of the gypsum plaster. The use of porous conch shell powder (CSP) as a bacterial carrier through immobilization approach is also proposed in this work. The effect of vacuum impregnation of bacteria in the CSP with and without nutritional coating was attempted, and the results suggested the plaster mixes displayed higher performance with vacuum impregnation and the compressive strength was raised by around 7% over the ordinary plaster. The developed plaster indicated greater strength with fewer pores and improved durability by displaying increased water tightness, and the process of calcite production was evident for a period of up to 28 days through UPV monitoring. As SEM and XRD studies showed, microbial calcite precipitation plugged up the pores, making the microstructure dense and more durable.