Organic Additive Significantly Boosts Strength of Soil Cemented in Enzyme-Induced Process

Achievement date: 
2017
Outcome/accomplishment: 

Increased strength was shown to result from adding an organic stabilizer to the solution that induces carbonate precipitation for ground improvement, according to research at NSF-funded Engineering Research Center (ERC) for Bio-mediated and Bio-inspired Geotechnics (CBBG), headquartered at Arizona State University.

Impact/benefits: 

Enzyme-induced carbonate precipitation (EICP) has the potential to replace Portland cement in various ground-improvement applications. The vastly improved strength realized from adding the organic stabilizer, as much as 10 times the strength achieved without the stabilizer, increases the potential of EICP for many applications.

Explanation/Background: 

Scientists at CBBG have developed a family of methods to cement soils, with the use of enzymes one of the more promising. EICP relies on the urease enzyme to start breaking down urea, releasing carbonate ions that help cement soil. EICP uses free urease derived from agricultural products.

EICP has the potential to reduce the costs and environmental impact associated with the manufacture of Portland cement by replacing it in certain construction applications, including stabilizing steep soil grades and excavation walls. The process also can reduce unhealthy dust that is emitted in arid and semi-arid regions in the southwest United States, while also reducing soil loss to wind erosion.