Biocementation of demolition wastes for geotechnical fills utilizing soybean and jack bean urease enzymes

Traditional methods of road construction utilizing virgin aggregates and cement have caused significant strains on the environment due to the high carbon output. To solve such a critical problem, this study evaluated the feasibility and efficiency of stabilizing recycled concrete aggregates (RCA) and crushed brick (CB) utilizing enzyme induced carbonate precipitation (EICP). Jack bean and soybean ureases were utilized for this study at various solution concentrations. Low temperature condition was found to increase the strength performance for soybean EICP treated samples due to the reduction in surface clogging. Jack bean urease was found to be less effective than soybean due to lower level of urea activity. The unconfined compressive strength (UCS) of soybean EICP treated samples showed the optimum strength at 60 g/L concentration while jack bean EICP treated samples expressed lower strength overall. Other tests such as calcium carbonate test, scanning electron microscope and X-ray diffraction were also presented.