Consolidation of Sand Particles by Nanoparticles of Calcite after Concentrating Ureolytic Bacteria In Situ

Abstract

ABSTRACT Ureolytic bacteria in the presence of high concentration of urea and calcium ions will precipitate calcite crystals in the form of nanocrystal aggregates. Those aggregates consolidate sandy materials by forming bridging points between sand particles. Bacterial cells that were isolated in a previous study, Bacillus sp. MCP11 (DSM 23526), were successfully concentrated in situ by up-loading 3-void volumes of cells followed by cementation solution (calcium/urea). Sandstone with UCS of 1200 kPa was formed with three applications of cells and cementation solution without clogging the void spaces resulting in a permeable consolidated sand core. ESEM images, EDS, and XRD analysis for the consolidated sandstone showed nanoparticles of rhombohedral calcite crystals aggregates of very fine particles at the nanoscale forming point-to-point contact between the sand particles.