Bacteria-Induced Cementation in Sandy Soils

Abstract

Bacteria-induced calcite precipitation (BICP) is a promising technique that utilizes bacteria to form calcite precipitates throughout the soil matrix, leading to an increase in soil strength and stiffness. This research investigated BICP in two types of sands under sterile and nonsterile conditions. Bacteria formation and BICP in the sterilized sand specimens are higher than those in the nonsterilized sand specimens. The development of calcite with time is initially greater for the sand specimens containing calcite. Scanning electron microscope imaging allowed the detection of cementation from calcite precipitation on the surface and pores of the sand matrix. The effects of injecting nutrient mediums and bacteria into the specimens, as well as pH of soil samples on BICP were investigated. The bearing capacity of biologically treated vs. untreated sand specimens were determined especially by laboratory foundation loading tests.

Keywords:

• bacteria
• bearing capacity
• cementation
• mineralogy
• sand
• sterilization

Acknowledgments

The authors are grateful for the SEM observations by Dr. Cemal Merih Sengonul at Atilim University and XRD by Dr. Zehra Karakas at Ankara University and some helps for Berat Cinar at Gazi University.