A Novel Approach for the Consolidation of Sand by MICP Single Treatment

Munich University of Applied Sciences HM, Department of Civil Engineering, 80333 Munich, Germany

^* Corresponding author: brigitte.nagy@hm.edu

Abstract

Saving natural resources has become increasingly important. In construction, research has been done on alternative methods to replace conventional building materials. One of those novel methods is MICP (microbial induced calcium carbonate precipitation). In this process, calcium carbonate crystals are precipitated with the help of ureolytic bacteria. A cementation solution consisting of urea and calcium salt is used. This precipitation can be used for solidification. In the field of MICP research, there exist multiple publications with several kinds of tests, but no verifiable compressive strength test. However, most researchers are concerned with soil improvement or self-healing methods, to fill cracks in concrete. Similarly, column tests are mainly conducted to investigate the strength. This study presents, a new method of strength assay that uses hardened sand samples of 3 cm edge length. This allows for an accurate compressive strength verification and thus the effect of the biocementation treatment. In addition, this method applies a single treatment method with a novel type of formulation of the MICP components. The results show that a single MICP treatment is sufficient for the consolidation of various sands. Compressive strength of up to 1.8 N/mm² was achieved in the process tests in the uniaxial strength test.