Abstract
PurposeInstability of slope surface is a critical concern in Geotechnical and Environmental Engineering. MICP (Microbial-Induced Carbonate Precipitation), an innovative bio-cementation technique, has attracted the attention for slope surface protection. In this work, MICP was investigated to evaluate its durability under the exposure of acid rain and to advance the understanding on long-term performance of slope soil preserved by MICP.MethodsMICP treatment was applied to a fine-grained slope soil using indigenous bacteria. Specimens treated to different cementation levels (% CaCO3) were exposed to acid rain (of varying pH) through two sorts of mechanisms: (i) infiltration and (ii) immersion. The evaluations were based on corrosion of CaCO3, mass loss, needle penetration tests, and scanning electron microscopy.ResultsThe decrease in pH increased the corrosion of CaCO3, resulting in considerable loss in aggregate and unconfined compressive strength. However, increased cementation level showed high durability of specimens. The soils treated to 12.5% CaCO3 showed 19.9% soil loss, whereas it was reduced to 5.4% when cemented to 22.5% CaCO3. The results also revealed that the contact time of acid rain significantly governed the rate of corrosion, i.e., specimens subjected to lower infiltration rate (20 mm/h) showed higher loss of mass compared to that of higher rate (100 mm/h).ConclusionThe long-term performance of MICP treatment is determined by (i) cementation level, (ii) pH, and (iii) infiltration rate of acid rain. High cementation level promotes the longevity of the treatment. Therefore, MICP to higher cementation level is recommended for long-term preservation of slope surface.
Highlights
Microbial-induced carbonate precipitation (MICP) is a novel bio-cementation technique, which has gained an increased attention among geotechnical researchers (DeJong et al 2010; Achal and Mukherjee 2015; Tang et al 2020)
The results revealed that the contact time of acid rain significantly governed the rate of corrosion, i.e., specimens subjected to lower infiltration rate (20 mm/h) showed higher loss of mass compared to that of higher rate (100 mm/h)
The measured pH in reacted solutions was observed to be in a range of 6.5–8.0, indicating that the dissolution of C aCO3 would consume the protons and neutralize the acid rain solution
Summary
Microbial-induced carbonate precipitation (MICP) is a novel bio-cementation technique, which has gained an increased attention among geotechnical researchers (DeJong et al 2010; Achal and Mukherjee 2015; Tang et al 2020). MICP is an environmentally friendly process that mediates nonpathogenic bacteria containing active urease enzymes. The bacteria are aerobically cultivated and introduced to the target soil along with the solution of urea. Journal of Soils and Sediments (2021) 21:2831–2844. H2N − CO − NH2 + 2H2O urease → CO23− + (1).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
