Microbially Induced Calcite Precipitation for the Improvement of Porous Building Stone

Microbially induced calcite precipitation (MICP) is becoming a common improvement technique for geological materials. Recently much attention has been focused on the use of MICP as a sustainable technique for improving granular (non- cemented) materials and the production of self-healing concrete. However, the application of induced carbonate precipitation for the protection of monument and building stone was developed in 1990. This preliminary study presents results of immersion MICP treatment on coquina core specimens. Photographs of the treated specimens showed biodeposition coating the surface of the specimens and spheroidal depositions in some surface pores. The MICP treatment increased the unit weight, decreased the absorption, and increased the bulk specific gravity of the specimens. The decrease in absorption resulted in a reclassification of the coquina for use a building stone. Attempts to develop relationships of percent increase in unit weight and percent decrease in absorption based on initial unit weights as an indirect measurement of porosity were unsuccessful. In order to develop such relationships porosity must be property quantified.