Effects of Microbiologically Induced Calcium Carbonate Precipitation (MICP) on Properties of Ancient Masonries in the Soil of Ancient Monument

Abstract

Most ancient monuments are sensitive to the change in environmental conditions. As a result, it is necessary to be concerned about restoring the monuments while preventing vibration and chemical contamination. Additionally, since ancient monuments cohabit with local microorganisms, it is essential to restore the site while considering the original habitat. This research investigates the potential of microbially induced calcium carbonate precipitation (MICP) on ancient bricks and mortar using Bacillus sphaericus LMG 22257 strain cooperating with local microorganism. Bricks and mortars were used for this study. The soil samples were taken from a site adjacent to a historical wall in Lopburi province with different preparations including, sterilized sand and natural local sand to compare the amount of calcium carbonate produced by MICP under treatment of 18 days. The surface profile of the material was analyzed using Scanning Electron Microscope (SEM), the mineral content by Energy Dispersive X-ray Spectrometer (EDS), and the pore depth on the material surface by 3D Optical Surface Profilers (3D Scan). The results revealed that the calcium carbonate content of the material grows on its surface by filling in the pores and some contents are fulfilled inside the surface of the bricks, resulting in an additional CaCO3 to be present in the materials.