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Updated: Jun 30, 2026

Sandy Soil Improvement through Microbially Induced Calcite Precipitation MICP by Immersion
Published on: September 12, 2019
Impact of soil density on biomineralization using EICP and MICP techniques for earthen sites consolidation
Jie Li1, Feiqing Zhu1, Fasi Wu1
1National Research Center for Conservation of Ancient Wall Paintings and Earthen Sites, Dunhuang Academy, Dunhuang, 736200, Gansu, PR China; Gansu Provincial Research Center for Conservation of Cultural Heritage, Dunhuang, 736200, PR China; Key Scientific Research Base of Conversation for Ancient Wall Paintings of National Cultural Heritage Administration, Dunhuang, 736200, Gansu, PR China.
Abstract:
Enzyme-induced calcium carbonate precipitation (EICP) and microbially-induced calcium carbonate precipitation (MICP) techniques represent emerging trends in soil stabilization. However, the impact of soil density on biomineralization, particularly in historical earthen sites, remains unclear. This study compares the consolidation effects of EICP and MICP on cylindrical samples (10 cm × 5 cm) with three densities (1.5 g/cm3, 1.6 g/cm3, and 1.7 g/cm3) derived from the soil near the UNESCO World Cultural Heritage Site of Suoyang Ancient City, Gansu Province, China. Results showed that calcium carbonate production increased across all densities through bio-cementation, with higher densities producing more calcium carbonate. MICP-treated specimens exhibited larger increases in calcium carbonate production compared to those treated with EICP. Specimens with a density of 1.7 g/cm³ showed a wave velocity increase of 3.26% (EICP) and 7.13% (MICP), and an unconfined compressive strength increase of 8% (EICP) and 26% (MICP). These strength increases correlated with the generation of calcium carbonate. The findings suggest that biomineralization can be effectively utilized for in situ consolidation of earthen sites, emphasizing the importance of considering soil density in biologically-based conservation technologies. Furthermore, MICP shows potential advantages over EICP in providing stronger, compatible and more sustainable soil reinforcement.
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