An Experimental Investigation on Use of Xanthan Gum Biopolymer as Additive for Improving the Reinforcement Effect of Biocementation on Sandy Soils

Abstract

The objective of this study is to evaluate the applicability and mechanism of xanthan gum (XG) biopolymer for improving the reinforcement effect of microbially induced carbonate precipitation (MICP) on sandy soils under completed drying and saturated conditions using triaxial consolidated undrained (CU) tests, unconfined compressive strength (UCS) tests, scanning electron microscopy (SEM) tests and X-Ray Diffraction (XRD) tests. Results of tests show that, in the CU tests, the shear strength and dilatancy of MICP combined with XG biopolymer (MICP-XG) treated sand are between those of MICP treated sand and XG treated sand, and decrease for increasing XG biopolymer concentration. The highest shear strength and dilatancy occur in the MICP treated sand. In the UCS tests, the unconfined compressive strength of the MICP-XG treated sand is significantly higher than that of MICP or XG treated sand, and increases with the increase of XG biopolymer concentration. In addition, the calcium carbonate content of MICP-XG treated sand is slightly lower than that of MICP treated sand. Combined with the microscopic tests results of each sample, it implies that xanthan gum biopolymer can effectively improve the strengthening effect of MICP on sandy soils under drying conditions, while it slightly weakens the strengthening effect of the MICP method under saturated conditions.

Keywords:

• Microbially induced carbonate precipitation
• xanthan gum
• triaxial consolidated undrained tests
• unconfined compressive strength tests

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The Project Supported by the National Natural Science Foundation of China (Projects No. 52208338), the Foundation of Key Laboratory of Soft Soils and Geoenvironmental Engineering (Zhejiang University), Ministry of Education (Projects No. 2022P06), the Fundamental Research Funds for the Central Universities (No. B240201166), the Key Research and Development Projects in Ningxia (No.2022BSB03067).