View of CDSM grid prior to construction of mat foundation

Project Highlights – Caribbean
Industrial Facility

Up to three soil mixing rigs worked two shifts tocomplete the project on time•

A soil-cement grid was constructedusing CDSM (Cement Deep SoilMixing) to improve ground stability,
control settlement and preventliquefaction of soils within thefoundation areas.

•Over 200,000 cubic yards of loose,silty sand, soft clay, and gravel were
improved by CDSM over a period offifteen months.

•Triple-shaft CDSM equipment wasused to improve soils to a depth of45 feet. Up to three CDSM soil
mixing rigs, working double shifts,
were used on the project site.

•CDSMconstruction
exceeded
unconfined compressive strength andsoil
mix
uniformity
designrequirements. Design specifications
for unconfined compressive strength
required an average of 100 psi at 28days.

•Project Owner: Confidential
General Contractor: Bechtel, Intl.

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Caribbean Industrial Facility
Incremental load test in progress

The CDSM (Cement Deep Soil Mixing) method was used to construct a grid
pattern of soil-cement columns under two 820-foot by 490-foot criticalindustrial facilities. The grids were created to prevent the generation ofexcessive pore water pressure during and after earthquakes and to preventthe liquefaction of soils within the foundation area.
Soil conditions encountered on the project consisted of reclaimed hydraulicfill that resulted in a heterogeneous mixture of loose, silty sands, soft silt andclay and gravel. Underlying the hydraulic fill at depths ranging from eightfeet to 28 feet below ground surface was the top of the natural younger
marine sediment layer, consisting of primarily loose to medium dense silty
sand and sand. Below the younger marine sediment layer was the oldermarine sediment, consisting of medium stiff to hard clay. Ground water was
encountered at three to six feet below the ground surface.

The soil-cement grids were designed to reinforce the liquefiable sandy soils
and soft clay lenses. Each soil-cement grid was 13.8 feet by 17.7 feet and was drilled to a maximum depth of 45 feet.
The soil-cement grid was formed using 3-foot diameter columns spaced on 2-foot centers.
A CDSM test section was performed prior to full production to verify that the CDSM equipment, procedures, and mix
design could produce the required soil improvement. Load tests were also performed during the test section todetermine the amount of settlement when loads were applied to soil-cement columns. Results from the test section
demonstrated that the CDSM walls would provide a soil-cement grid of adequate strength, satisfying the geometric,strength and uniformity requirements. The test section also demonstrated that the soil-cement columns would limit
settlement within the design values.
Over 200,000 cubic yards of CDSM soil improvement was constructed over a
period of fifteen months. Triple-shaft CDSM equipment was used for thisproject to a maximum depth of 45 feet. Drilling depth, penetration/withdrawal
speed, shaft rotation and slurry injection rates were monitored in real-time andrecorded in 3-foot depth increments to assure accurate mixing control and a
uniformly mixed soil-cement product.
Test specimens for unconfined compressive strength were retrieved by a triple
barrel coring system, and exceeded the acceptance criteria of an average of 100
psi at 28 days.
Load test layout
Pacific DivisionCorporate Headquarters
1660 Factor Avenue
San Leandro, CA 94577
510-346-9840
510-346-9841 fax

Toll Free: 1-866-DEEPMIX
Website: www.raitoinc.com
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Atlantic Division6210 North King's Highway
Alexandria, VA 22303
703-718-0755
703-718-0744 fax