Comparison of the Ability of Two Bacteria to Improve the Behavior of Sandy Soil

This paper presents a laboratory study of the ability of two bacteria to improve the geomechanical properties of a sandy soil by calcium carbonate precipitation. The performance of two bacteria (Sporosarcina pasteurii and Idiomarina insulisalsae) is compared, based on unconfined compressive strength and splitting tensile strength tests. The effects of curing time and the concentration of I. insulisalsae on the strengthening process are also analyzed. Although the optimum environmental conditions for the bacterial growth were not adopted, the potential to improve the geomechanical properties of natural sandy soils is shown by the results. The bacteria I. insuliasalsae is shown to be more efficient than S. pasteurii in strengthening the soil, and increases in the concentration of I. isuliasalsae induce an increase in the geomechanical properties. However, this effect is not proportional to the amount of bacteria, probably due to a lack of nutrient. (C) 2014 American Society of Civil Engineers.