This study evaluated the effect of bio-cementation (MICP) on cone penetrometer measurements in soil. Large scale tests were conducted to quantify how cemented soil behaves during cone penetration testing. Both bio-stimulation and bio-augmentation techniques for cementing the soil were found to be effective and comparable at a large scale. Attempting to detect lightly cemented soil based only on tip resistance and sleeve friction ratios was unreliable. The best indication of light cementation was the presence of calcite deposits. Cone penetration tests on the treated soils showed that cementation increased tip resistance measurements.

1. Effect of Bio-Cementation on
Cone Penetrometer Measurements
Collin M. Anderson, M.S. (June 11, 2015)
Advisors: Jason T. DeJong & Douglas C. Nelson
1.Both bio-stimulation and bio-
augmentation work, and are
comparable at the large scale.
2.Attempting to detect lightly
cemented soil using only tip
resistance and sleeve friction
ratio is shown to be unreliable.
3.The best indication of lightly
cemented soil is evidence of
calcite.
The project was possible with
funding from the National
Science Foundation. The help,
advice and patience from
Michael Gomez, Prof. DeJong,
Prof. Nelson, Bill Sluis, Daret
Khalet, Matt Havey, Steve
Purugganan, Charlie Graddy,
and Jason Wong is also
acknowledged.
MICP (Microbially Induced Calcite
Precipitation), or bio-cementation, is
a novel process by which bacteria in
soil are stimulated to produce a
cementing compound, Calcite
(CaCO3), at the particle-particle
contacts resulting in drastically
increased strength. Large scale tests
were performed to evaluate feasibility
of field testing and quantify behavior
of cemented soil during cone pushing
(not possible at small scale).
Eight cone soundings established
baseline conditions and assed soil
uniformity.
Spatial mapping of qt values at mid
depth confirm the pumping method
achieved the goal of creating gradients
of cementation.
Results of averaged values at mid-depth (ΔVs1 and ΔGo) and full
depth (calcite) vs. average Δqt1n at that depth (± 2.5 cm)
30 full depth soundings performed post treatment quantified behavior of cemented soils during CPT
testing. Five typical profiles are presented for qt, qt1n. Δqt1n, and fs for the Bio-stimulation. Mid depth
averages between tanks were nearly identical (see Spatial Variability).
Averaged values at mid-depth with calcite contours shown in red
Region B
Region A
Region C
Yolo
Loam
Top Cap
Concrete
Sand
String Pot
To DAQ
System
Steel Cross
Beams
Mini-
Cone
Smooth
Sleeve
Waterproof
Rubber Liner
2,000 lbs.
Load
Thin, Plastic
Liner
Bio-StimulationBio-Augmentation
3%
5%
1%
3%
5%
1%
Measuredtipresistance,qt(MPa)
W1
W2W3
W1
W2W3