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Effect of cementation reagents concentrations on microbial calcite precipitation in residual soil
Murtala Umar1, Khairul Anuar Kassim2.
Microbially induced calcite precipitation has been under investigation since early
1990s for its potential application in improving the strength and durability of construction
materials such as limestone and cementitious materials. However, excellent results demonstrated
by this technique in the studies so far conducted have shown greater potential of exploring its
wider applications in geotechnical engineering. This study examines the microbial carbonate
precipitations in tropical residual soil via urea hydrolysis. An isolate of urease active strain of
Klebsiella pneumoniae UM123 was used to precipitates calcite into the soil with the aim of
improving the strength and reducing the hydraulic conductivity of the soil. Cementation reagents
concentrations of 0.25, 0.5, 0.75, 1.0 and 1.5M were used to evaluate the strength and hydraulic
conductivity of the soil using treatment durations of 24, 48 and 60 hours. Meanwhile, bacteria
concentrations of 1.5×104 cfu/ml and 2.9×106 cfu/ml were used to assess the effect of microbial
concentrations in the study. The results obtained indicated a general increase in the strength of
the treated soil as the bacteria concentrations increases. Likewise, the strength also increases with
the increase in reagents concentrations up to 0.5M after which the strength declined. The
hydraulic conductivity also decreased by 50% and 65% after 48 hours for 1.5×104
cfu/ml and
2.9×106
cfu/ml bacteria concentrations. The results so far obtained revealed that the optimum
reagent concentration for this particular microorganism for efficient soil improvement is 0.5M.
Affiliation:
- Universiti Teknologi Malaysia, Malaysia
- Universiti Teknologi Malaysia, Malaysia
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