Federal Highway Administration Design Manual: Deep Mixing for Embankment and Foundation Support

Classification

WRS

WRS

Company

Geo-Con, Inc., Raito, Inc., JAFEC USA, Inc., and Fudo

SMW Seiko, Inc., Raito, Inc., JAFEC USA, Inc., etc.

Geography

North America

Southeast Asia and United States

General Description of Most Typical Method

Multiple discontinuous augers on hanging leads rotate in alternate directions. Most of grout injected on downstroke to create panels. Neither air nor water typically used during penetration. Reverse rotation during withdrawal.

Multiple discontinuous augers on fixed leads rotate in alternate directions. Water, air, or grout used on downstroke and/or grout on upstroke.

Special Features/Patented Aspects

Lower 3 m usually double stroked. Strong QC/QA by electronic methods.

Special electric head and gear box patented. Double-stroking oscillation common, especially in cohesive soils. Discontinuous auger flights and paddles are positioned at discrete intervals to reduce torque requirements. Good control over verticality feasible. Auger type varies with soil.

Details of Installation

Shafts

1 to 6, usually 4

3 to 5, usually 3

Diameter

0.8 to 1.0 m (usually 0.9 m)

0.55 to 0.9 m (usually 850 to 900 mm)

Realistic maximum depth

45 m possible, 27 m common

60 m claimed, 35 m practical

Revolutions per minute

15 to 25

15 to 40 during penetration depending on soil; higher during withdrawal

Productivity/ output

0.6 to 1.0 m/min penetration (slower in clays and dense sands); 2 m/min withdrawal/mixing; 100 to 150 m²/shift industrial

0.5 to 1.5 m/min penetration; 1.5 to 2 m/min withdrawal/mixing; 100 to 200 m³ per shift (i.e., 100 to 150 m² per shift)

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout ± bentonite ± clay and other materials and additives such as ash and slag

Cement grout ± bentonite and other additives such as ash, slag

w:c

1.2 to 1.75 (typically 1.5 on penetration and 1 to 1.25 during withdrawal)

1.50 to 2.50 (sands), 3.0 (cohesives)

Binder factor

120 to 400 kg/m³

200 to 750 kg/m³

Volume ratio

15 to 40 percent

35 percent or more

Reported Treated Soil Properties

Unconfined compressive strength

0.3 to 7 MPa (clay strengths approximately 40 percent of those in sands); In sands, 2+ MPa

0.5 to 1.0 MPa (clays); 0.5 to 3.0 MPa (sands)

Permeability

1 × 10^-7 to 1 × 10^-9 m/s

1 × 10^-7 to 1 × 10^-10 m/s

Young's modulus

300 to 1,000 × unconfined compressive strength

ND

Specific Relative Advantages and Disadvantages

Economical, proven systems; mixing efficiency can be poor in stiff cohesive soils (especially SMW Seiko); can generate large spoil volumes, proportional to volume ratio required for mixing efficiency and treated soil requirements

Notes

First DSM application at Bay City, MI in 1987

Developed by Seiko in 1972: first used 1976 in Japan, 1986 in U.S. Trade Association in Japan

Representative References

Ryan and Jasperse; Day and Ryan; Nicholson (See references 138-140 and 127)

Taki and Yang; Yang ^(141-143)

Classification

WRS/WRE

WRS

Company

TREVI

Bachy

Geography

Worldwide

Europe

General Description of Most Typical Method

Multiple cable-suspended augers rotate in opposite directions. Grout injected during penetration. Prestroked with water in cohesive soils (if required). Auger rotation reversed during withdrawal.

Counter-rotating mixing shafts from fixed leads penetrate ground while slurry is injected. Blended soil moves from bottom to top of hole during penetration and reverses on withdrawal. Restroking of columns in cohesive soils.

Special Features/Patented Aspects

Real-time recording of drilling and grouting parameters. Developed especially for cohesionless soils of low/medium density and cohesive soils.

6 to 8 auger machines noted in Australian patent (1995). Changing direction of augers during extraction compacts columns. Patented in United States 4,662,792 (1987). Automatic drilling parameter recorder synchronizes slurry injection and penetration rates.

Details of Installation

Shafts

1 to 3 (configuration varies with soil)

2, 3, or 4 common (6 to 8 possible)

Diameter

0.55 to 0.8 m at 0.4- to 0.6-m spacing

0.23 to 0.85 m

Realistic maximum depth

25 m

20 m (10 m common)

Revolutions per minute

12 to 30

ND

Productivity/ output

0.35 to 1.5 m/min penetration; 0.5 to 2.0 m/min withdrawal

0.8 m/min penetration; 1.0 m/min withdrawal; 200 to 300 m/shift

Mix Design (depends on soil type and strength requirements)

Materials

Cementitious grout, additives may be used

Cement, lime, flyash, and special grouts to absorb heavy metals and organics

w:c

Typically low (i.e., 1.25 to 0.8 by weight)

1.0 typical, but wide range

Binder factor

150 to 250 kg/m³ typical

Up to 320 kg/m³ (200 kg/m³ typical)

Volume ratio

15 to 40 percent

30 to 50 percent

Reported Treated Soil Properties

Unconfined compressive strength

5 to 30 MPa (granular soils); 0.2 to
1 MPa (silts and clays)

3 to 4 MPa (clay), higher for sands

Permeability

< 1 x 10^-8 m/s

< 1 x 10^-7 m/s

Young's modulus

ND

50 to 100 × unconfined compressive strength

Specific Relative Advantages and Disadvantages

Goals are to optimize the quality of mixing and speed of installation and to minimize the amount of spoil

Low spoil claimed. Can be used on slopes and adjacent to structures. Columns have 10 to 20 percent larger diameters than shafts due to compaction effect. Flexible equipment and mix design.

Notes

Developed by TREVI

Developed in France in late 1980s

Representative References

Promotional materials from TREVI

Harnan and Iagolnitzer ⁽¹⁴⁴⁾

Classification

WRS

WRS

Company

Shimizu Corporation

More than 48 members of CDM Association in Japan and offered in United States by Raito, Inc., JAFEC USA, Inc., and Fudo

Geography

Japan

Japan, China

General Description of Most Typical Method

Upper continuous auger flights on fixed leads extract soil to ground surface during penetration. Lower mixing blades rotate and mix soil with injected slurry during withdrawal.

Fixed leads support shafts with two to six mixing blades above drill bit. Grout injected during penetration and (mainly) withdrawal. Also a 2- to 8-min mixing period at full depth.

Special Features/Patented Aspects

Continuous flight augers from drill tip to the ground surface remove soil to limit ground displacements and lateral stresses during mixing.

Comprises numerous subtly different methods all under CDM Association

Details of Installation

Shafts

2

2 to 8 (marine); 1 to 6 (land) (each with 4 to
6 blades) (12 have been used)

Diameter

1 to 1.2 m

1 to 1.6 m (marine); 0.7 to 1.6 m (land)

Realistic maximum depth

40 m

70 m (marine); 40 m (land)

Revolutions per minute

ND

20 to 40 (penetration); 20 to 40 (withdrawal)

Productivity/ output

ND

0.5 to 2 m/min (avg. 1 m/min) (penetration)
1 to 2 m/min (withdrawal) (1,000 m³/shift for marine; 100 to 200 m³/shift on land)

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout

Wide range of materials, including PCC or slag cement, bentonite, gypsum, flyash, using fresh or seawater, plus various additives.

w:c

ND

0.6 to 1.3, typically 1.0

Binder factor

ND

100 to 300 kg/m³, typically 140 to 200 kg/m³

Volume ratio

ND

20 to 30 percent

Reported Treated Soil Properties

Unconfined compressive strength

0.5 MPa (in soft silt) (70 percent of conventional DMM)

Strengths can be closely controlled by varying grout composition from
< 0.5 to 4 MPa (typically 2 to 4 MPa)

Permeability

ND

1 x 10^-8 to 1 x 10^-9 m/s

Young's modulus

ND

ND

Specific Relative Advantages and Disadvantages

Reduces horizontal displacements and stresses imposed during mixing. Obviates need for pre-augering.

Vast amount of information available. Specifically developed for softer marine deposits and fills, now also used for land-based projects.

Notes

Operational prototype stage. Possibly patented (assumed similar to CDM).

Association founded in 1977. Research initiated under Japanese Government (1967).

Representative References

Hirai et al. ⁽¹⁴⁵⁾

Promotional material from Cement Deep Mixing Method Association; Okumura ⁽¹⁴⁶⁾

Classification

WRE

WRE

Company

Geo-Con, Inc. and Raito, Inc.

Envirocon, Inc.

Geography

United States

United States

General Description of Most Typical Method

Single large-diameter auger on hanging leads or fixed rotary table is rotated by bottom rotary table and slurry or dry binder is injected. Auger rotation and injection continue to bottom of treated zone. Auger rotation during withdrawal usually without injection.

Use of single shaft wet Kelly bar mixing auger or blades rotated by a top drive track-mounted hydraulic drill. Grout mixed onsite using automated batch plant with typically one to two dry components.

Special Features/Patented Aspects

Single large-diameter auger cycling up and down is common to improve mixing efficiency.

Instrumentation documents all major parameters, on-board GPS unit for survey control.

Details of Installation

Shafts

1 to 6, usually 4

1

Diameter

0.8 to 1.0 m, usually 0.9 m

2 to 3 m

Realistic maximum depth

45 m possible, 27 m common

12+ m

Revolutions per minute

15 to 25

10 to 25

Productivity/ output

0.6 to 1.0 m/min penetration (slower in clays and dense sands); 2 m/min withdrawal/mixing; 100 to 150 m²/shift industrial

300 (with 2-m diameter auger) to 800 m³ (with 3-m diameter auger) per shift

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout, bentonite, clay, and other materials and additives such as ash, slag, etc.

Primarily portland or slag cement-based grouts. Other additives: bentonite (for permeability) and reagents for environmental applications.

W:c ratio

1.2 to 1.75 (typically 1.5 on penetration and 1 to 1.25 during withdrawal)

0.8 to 1.8

Binder factor

120 to 400 kg/m³

150 to 300 kg/m³

Volume ratio

15 to 40 percent

15 to 30 percent

Reported Treated Soil Properties

Unconfined compressive strength

0.3 to 7 MPa (clay strengths approximately
40 percent of those in sands); In sands,
 2+ MPa

2 to 20 MPa

Permeability

1 × 10^-7 to 1 × 10^-9 m/s

1 × 10^-7 to 1 × 10^-9 m/s

Young's modulus

300 to 1,000 unconfined compressive strength

Unknown

Specific Relative Advantages and Disadvantages

Can treat variety of contaminants, including creosote, tar, organics, petroleum, etc.

Cost and schedule when compared to other alternatives. No dewatering.

Notes

Mainly used for environmental applications to date, but increasing use in geotechnical field

Used mainly for ISS of contaminated soils (environmental) and as an alternative deep foundation for large loaded areas (i.e. tank foundations).

Representative References

Walker; Day and Ryan;
Nicholson et al.^(11,140,147)

Andromalos and Ameel;
Andromalos et al. ^(148,149)

Classification

WRE

WRE

Company

Raito Kogyo, Co. offered in United States by Raito, Inc.

Shimizu

Geography

Japan

Japan

General Description of Most Typical Method

Large diameter, single-shaft, concentric double-rod system on fixed lead is rotated at high rpm into ground and grout injected over zone to be treated. Unit cycled up and down through zone with or without additional grout injection.

A pair of laterally connected shafts with horizontal mixing blades and vertical vanes are rotated during penetration. Grout injection during penetration and/or withdrawal. Vertical vanes create rectangular elements.

Special Features/Patented Aspects

Cutting blade on inner rod rotates in opposite direction from two mixing blades on outer rod. Slurry injection ports located at base of inner rod.

Use of claw-like vanes to create rectangular columns; vanes may be patented. Inclinometer fixed to mixing unit to monitor verticality.

Details of Installation

Shafts

1

2

Diameter

1.4 and 2.0 m (larger than typical CDM)

1- by 1.8-m columns

Realistic maximum depth

24 m typical; 28 m possible.

15 m

Revolutions per minute

Up to 40 (in each direction)

ND

Productivity/ output

0.5 m/min penetration; 1 m/min withdrawal

1 m/min penetration/withdrawal

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout

Cement grout

w:c ratio

0.8 (field trial)

ND

Binder factor

300 kg/m³ (field trial)

ND

Volume ratio

33 percent (field trial)

ND

Reported Treated Soil Properties

Unconfined compressive strength

1 to 6 MPa

ND

Permeability

ND

ND

Young's modulus

ND

ND

Specific Relative Advantages and Disadvantages

Large-diameter auger speeds production, computer control and monitoring, and uniform mixing. Especially useful in dense soils.

Rectangular columns require less overlap than circular. Vertical flow during mixing and larger cross sectional column area per stroke.

Notes

Assumed similar to CDM

Operational prototype stage. Assumed similar to CDM

Representative References

Isobe et al.⁽¹⁵⁰⁾ 

Watanabe et al.⁽¹⁵¹⁾ 

Classification

WRE

WRE

Company

Daisho Shinko Corp.

Terra Constructors

Geography

Japan

United States

General Description of Most Typical Method

Mixing shaft rotated, "box casing" conveyed (without rotation), and grout injected during penetration. Shaft is counter-rotated during withdrawal.

Large-diameter mixing tool on hanging leads rotated with slurry injection during penetration.

Special Features/Patented Aspects

Use of box casing, which surrounds mixing tools and contains treated soil to create square or rectangular columns.

Multiple-auger mixing capability foreseen for deeper applications.

Details of Installation

Shafts

1 to 4 horizontal mixing blades

1

Diameter

1-m square box

1 to 3.6 m

Realistic maximum depth

ND

13 m maximum

Revolutions per minute

30 (shaft only)

8 to 16

Productivity/ output

0.5 m/min penetration; 1 m/min withdrawal

380 m³/8-h shift

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout

Cement grout mainly and other additives for oxidation/stabilization of contaminants.

w:c ratio

1.0 to 1.2

0.75 to 1.0

Binder factor

150 to 400 kg/m³

ND

Volume ratio

ND

10 to 20 percent by weight

Reported Treated Soil Properties

Unconfined compressive strength

1.2 to 4.2 MPa

Varies dependent upon soil type;
up to 3.5 MPa

Permeability

ND

Similar to in situ soil

Young's modulus

ND

ND

Specific Relative Advantages and Disadvantages

Square/rectangular columns require less overlapping than circular columns. Uniform mixing promoted.

Applicable in soils below water table. Environmental applications.

Notes

Operational prototype stage. Assumed similar to CDM.

Developed since 1995.

Representative References

Mizutani et al.⁽¹⁵²⁾

Promotional material from Terra Constructors

Classification

WRE

WRE

Company

Kvaerner Cementation

Hayward Baker Inc., and Keller Co.

Geography

United Kingdom

United States (with opportunities for sister companies worldwide)

General Description of Most Typical Method

Single auger on fixed leads rotated during penetration. Auger cycled up and down through 1-m length five times then raised to next 1-m increment. Repeat to surface. Injection upon penetration, cycling, and/or withdrawal.

Mast mounted shaft rotated by top rotary drive. Grout injected usually during penetration, followed by bottom remixing and oscillation at full depth and rapid extraction with injection of backfill grout only (1 to 5 percent total).

Special Features/Patented Aspects

Combination of a short interrupted length of auger with smaller diameter continuous flights.

ND

Details of Installation

Shafts

Single with 2 or 3 pairs of mixing paddles above drill bit.

1

Diameter

0.5 to 2.4 m, typically 2.1 and 2.4 m

0.75 m (1 m also possible)

Realistic maximum depth

20 m maximum

10+ m

Revolutions per minute

20 to 60 (penetration); higher upon withdrawal

ND

Productivity/ output

0.3 to 0.5 m/min (penetration); faster upon withdrawal. In excess of 500 m³/shift

0.5 to 0.67 m/min penetration/mixing

Mix Design (depends on soil type and strength requirements)

Materials

Varied in response to soil type and needs

Cement grout with or without flyash

w/c ratio

1 to 2 (typically at lower end)

0.4

Binder factor

150 to 400 kg/m³

60 to 130 kg/m³

Volume ratio

25 to 50 percent

Unknown

Reported Treated Soil Properties

Unconfined compressive strength

3.5 to 10 MPa (sands); 0.2 to 1.4 MPa (clays)

5 to 10 MPa

Permeability

1 × 10^-7 m/s possible

ND

Young's modulus

50 to 150 ksi

ND

Specific Relative Advantages and Disadvantages

Low spoil, low heave potential, specific horizons can be treated, good in saturated ground where dewatering cannot be used.

Good mixing; moderate penetration capability; low spoils volume. Dry binder method also available.

Notes

Not now apparently used in U.K. due to market conditions.

In development since 1990. Commercially viable since 1997.

Representative References

Greenwood ⁽¹⁵³⁾

Burke et al.; Burke and Sehn ^(154,155)

Classification

WRE

WRE

Company

INQUIP Associates

Bauer Maschinen (manufacturer); offered in United States by Bauer Foundations, Malcolm Drilling, Inc., Nicholson Construction, and Golder Associates Innovative Applications, Inc.

Geography

United States and Canada

Europe (manufacturer), international (approximately 20 countries)

General Description of Most Typical Method

Single rotating shaft and bit; grout injection

Mixing head based on Bauer trench cutter technology; hydraulically driven rotating milling heads attached to monokelly. Binder injection typically during penetration; one phase (binder slurry for down and upstroke) and two phase (bentonite slurry for downstroke and binder slurry for upstroke). Air used for both systems mainly during downstroke.

Special Features/Patented Aspects

Proprietary to INQUIP Associates

Equipment and process patented; inclinometers monitor in two directions, system fully steerable

Details of Installation

Shafts

Single rotating bit with paddles

1 (2 cutter heads)

Diameter

1.2 to 4.8 m

Panel length 2.4 to 2.8 m; panel width
0.55 to 1.2 m

Realistic maximum depth

3 to 30 m (depends on auger diameter)

43 m (kelly suspended)
60 m (rope suspended)

Revolutions per minute

5 to 45

35

Productivity/ output

ND

Penetration up to 0.5 m/min; withdrawal 0.3 to 1.0 m/min; production: 33 m³/hr

Mix Design (depends on soil type and strength requirements)

Materials

Cement

Cement slurry ± bentonite ± other materials such as flyash and slag

w:c ratio

0.8 to 2 typical

0.5 to 1.0 (retaining walls); 2.0 to 4.0 (cutoff walls)

Binder factor

> 100 kg/m³

100 to 500 kg/m³ (up to 600 kg/m³ has been used)

Volume ratio

> 15 percent

30 to 60 percent

Reported Treated Soil Properties

Unconfined compressive strength

> 0.1 MPa

5 to 15 MPa (retaining walls); 0.5 to
2.0 MPa (cut off walls)

Permeability

< 1 × 10^-8 m/s typical

1 × 10^-7 to 1 × 10^-9 m/s

Young's modulus

ND

N/D

Specific Relative Advantages and Disadvantages

Good penetration/mixing. Dry binder available for use in treating sludges.

Extended depths (up to 60 m) can be reached using rope-suspended cutters. Computer control of production parameters. Full QA reports of production parameters as a function of depth or time. Penetration through harder layers, including very soft rock

Notes

Developed in 1990, mainly used for environmental applications. Limited data.

Developed in 2004

Representative References

Promotional material from INQUIP Associates.

Brunner et al.; Gerressen and Vohs; Bellato et al.^(156-158)

Classification

WJE

Company

Taisei Corporation, etc.

Geography

Japan and United States

General Description of Most Typical Method

With blade retracted, 0.6-m-diameter pilot hole is rotary drilled to bottom of zone to be treated. Blade expanded and zone is treated with rotary mixing to
2-m diameter and air jetting to
3.6-m diameter.

Special Features/Patented Aspects

Retractable mixing blade allows treatment of specific depths to large diameter. Concentric mechanically mixed and jet mixed zones are produced. Patented trade association.

Details of Installation

Shafts

1

Diameter

0.6-m pilot hole, 2.0- (mechanical) to 3.6-m (jetted) column

Realistic maximum depth

40 m

Revolutions per minute

ND

Productivity/ output

0.03 to 0.1 m/min penetration

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout

w:c ratio

ND

Binder factor

450 kg/m³

Volume ratio

ND

Reported Treated Soil Properties

Unconfined compressive strength

0.4 to 4.4 MPa (mechanically mixed zone); 1.5 MPa (sandy), 1.2 MPa (cohesive) (jet-mixed zone)

Permeability

1 × 10^-8 m/s

Youngs modulus

150 × unconfined compressive strength (mechanically mixed zone);
100 × unconfined compressive strength (jet-mixed zone)

Specific Relative Advantages and Disadvantages

Variable column size generated by varying pressures; retractable/expandable blade; jet mixing allows good contact with adjacent underground structures in difficult access areas.

Notes

SWING Association with 17 members established in late 1980s in Japan.

Representative References

Kawasaki; Yang et al.^(159,160)

Classification

WJE

WJE

Company

Chemical Grout Co., Fudo Co., and others

Onoda Chemical Co., Ltd.

Geography

Japan

Japan

General Description of Most Typical Method

Twin counter-rotating shafts, grout injected at low pressure from cutting blades during penetration. During withdrawal, inclined crossed jets on upper two pairs of blades are used at high velocities to increase diameter and enhance mixing efficiency.

The mixing tool is rotated to full depth. Tool is withdrawn (rotating) to break up and remove the soil followed by repenetration to full depth. Grout is injected during second withdrawal via jets at high pressure.

Special Features /
Patented Aspects

The combination of DMM and jet grouting promotes good joints between adjacent columns and columns of controlled diameter and quality. Column formed is nominally 1.9 by 2.7 m in plan. Patented process. Trade association.

Conventional jet grout equipment with addition of single-blade auger to reduce volume of material displaced by jet and, therefore, limit ground movement (i.e., make volume injected equal to volume removed).

Details of Installation

Shafts

2 shafts at 0.8-m spacing each with 3 blades.

1

Diameter

1 m (blades at 0.8-m spacing along shaft)

About 1.0 m (jetted)

Realistic maximum depth

20 m

20 m

Revolutions per minute

20

3 to 40

Productivity/ output

1 m/min penetration; 0.5 to 1 m/min withdrawal

0.33 m/min penetration. Overall, about 65 percent of jet grouting.

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout

Cement grout

w:c ratio

1.0

ND

Binder factor

200 kg/m³ (jetted); 320 kg/m³ (DMM). Air also used to enhance jetting

ND

Volume ratio

200 L/min per shaft during DM penetration; 300 L/min per shaft during withdrawal (jetting) (i.e., 20 to 30 percent)

About 40 percent

Reported Treated Soil Properties

Unconfined compressive strength

2 to 5.8 MPa (silty sand and clay); 1.2 to
3 MPa (silty sand)

2 MPa

Permeability

ND

ND

Young's modulus

ND

ND

Specific Relative Advantages and Disadvantages

New system combining DMM and jet-grouting principles to enhance volume and quality of treatment; jetting provides good overlap between columns.

Repenetration causes production to be low. Spoil volume approximately equal to injected volume. Minimal ground heave.

Notes

Name is an acronym for jet and churning system management.

Operational prototype stage. Assumed similar to conventional jet grouting.

Representative References

Miyoshi and Hirayama ⁽¹⁶¹⁾

Ueki et al.⁽¹⁶²⁾

Classification

WJE

WJE

Company

Condon Johnson and Associates (CJA)

Geo-Con, Inc.

Geography

Western United States

United States

General Description of Most Typical Method

Grout is jetted via ports on a "processor" during rapid penetration. The wings cut the soil and the jetted grout blends it.

Drill with water/bentonite or other drill fluid to bottom of hole. No compressed air used. At bottom, start low-pressure mechanical mixing through shaft. Cycle three times through bottom zone. Multiple high-pressure jets started at same time
(350 to 450 MPa).

Special Features/Patented Aspects

Combination of mechanical and hydraulic cutting/mixing gives high-quality mixing and fast penetration. Licensed by CJA for five western States. TREVIICOS for the remainder. Very low environmental impact.

2-mm-diameter "hydra" nozzles on outer edges of mixing tool. Mechanical mixing occurs in center of columns, chunks of soil forced to perimeter where disaggregation occurs by jets.

Details of Installation

Shafts

1 shaft with pair of wings or similar "processor"

1

Diameter

0.6 to 1.2 m

1.2-m paddles on 0.9-m auger; column up to 2-m diameter depending on jet effectiveness.

Realistic maximum depth

45 m maximum (25 m typical)

20+ m

Revolutions per minute

150 to 200 (recent developments focusing on 80 to 90 rpm)

10 to 20

Productivity/ output

2 to 12 m/min (penetration) (6 m/min typical) 15 m/min (withdrawal); 150 m of piles/h possible

Up to 500 m³/shift

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout; additives if necessary

Cement

w/c ratio

0.5 to 1.5 (typically 0.8 to 1.0)

1.0 to 1.5

Binder factor

150 to 300 kg/m³ 

100 to 250 kg/m³

Volume ratio

20 to 40 percent

10 to 15 percent by weight of soil

Reported Treated Soil Properties

Unconfined compressive strength

0.7 to 5.5 MPa (Bay mud); 4.8 to
10.3 MPa (Beaumont clay)

Up to 10 MPa

Permeability

ND

Up to 1 × 10^-9 m/s

Young's modulus

ND

100 to 300 × unconfined compressive strength

Specific Relative Advantages and Disadvantages

Computer control of penetration parameters excellent; high strength; low spoil volumes; high repeatability; excellent mixing; high productivity.

No air used. Very uniform mixing. Control over diameters provided at any depth. Several times cheaper than jet grouting. Mixing can be performed within specific horizons (i.e., plugs can be formed instead of full columns).

Notes

Developed since early 1990s. Fully operational in Bay Area. Five patents on processor system and computer control; three patents pending.

Field-tested at Texas A&M. Fully operational from 1998.

Representative References

Reavis and Freyaldenhoven⁽¹⁶³⁾

Geo-Con, Inc.; Nicholson and Jasperse^(164,165)

Classification

WRS

WRE

Company

Raito

TREVI

Geography

Worldwide

Worldwide

General Description of Most Typical Method

Combines features of mechanical deep mixing and jet mixing methods to produce large diameter soil-cement columns. The low blade contains a port to deliver high-pressure jet and rotates in the reverse direction of the upper two levels of blades to provide the shearing and blending action needed for uniform mixing of soils and cement grout.

Single or multiple cable-suspended augers rotate in opposite directions. Grout is injected at high pressure during penetration, which enhances the mixing of soil with the grout. Auger rotation is reversed during withdrawal. Mixing is performed with a special tools located at the tip of the rods.

Special Features/Patented Aspects

Real-time monitoring and recording of installation parameters. The center portion of the column is a deep mixing column and the outside ring is a jet grouting product. The process is patented by Raito.

Real-time recording of drilling and grouting parameters (DMS System). Developed especially for cohesive soils peaty layers and sands.

Details of Installation

Shafts

1

Single axis or multiple axis (2, 3, or 4).
Configuration varies with soil.

Diameter

2 to 4.0 m

0.80 to 2.0 m

Realistic maximum depth

40 m

25 to 30 m

Revolutions per minute

2 to 40

30 to 50

Productivity/ output

0.03 to 1.5 m/min

10 to 80 m³/hr

Mix Design (depends on soil type and strength requirements)

Materials

Cement grout

Cementitious grout with or without additives

w/c ratio

100 percent

Typically low (i.e., 1.5 to 0.8 by weight)

Binder factor

150 to 350 kg /m³

150 to 250 kg/m³ typical

Volume ratio

20 to 45 percent

15 to 40 percent

Reported Treated Soil Properties

Unconfined compressive strength

1 to 3 MPa

5 to 30 MPa (granular soils); 0.2 to
2 MPa (silts and clays)

Permeability

ND

< 1 × 10^-7 to 1 × 10^-8 m/s

Young's modulus

ND

100 to 1000 × unconfined compressive strength

Specific Relative Advantages and Disadvantages

Large diameter soil-cement columns with high level of uniformity for ground stabilization

Goals are to optimize the quality of mixing and speed of installation and to minimize the amount of spoil

Notes

Developed by Raito Kogyo, Co. Ltd.

Developed by TREVI

Representative References

N/A

Siepi and Bertero; Schmutzler et al.^(166,167)

Classification

WVP

DRE

Company

Hayward Baker Inc., A Keller Co.

DJM Association (64 companies)

Geography

United States (but with opportunities for sister companies worldwide)

Japan

General Description of Most Typical Method

Mast-supported hydraulic chain drive using cutter bits traveling vertically along a post inserted to design depth.

Shafts are rotated while injecting compressed air from the lower blades to avoid clogging of jet nozzles. Dry materials are injected during withdrawal via compressed air and with reverse rotation. Air vents to surface around the square section shafts.

Special Features/Patented Aspects

Method licensed from patent holders.

System is patented and protected by DJM Association. Two basic patents (blade design and electronic control system). Many supplementary patents.

Details of Installation

Shafts

Continuous as the cutter post travels along an alignment

1 to 2 shafts adjustably spaced at 0.8 to about
1.5 m, each with 2 to 3 pairs of blades

Diameter

0.55 to 0.85 m

1 to 1.3 m

Realistic maximum depth

30 to 50 m max., depending on base machine employed

33 m maximum

Revolutions per minute

Chain speed is variable

5 to 64 during penetration. Twice as high during withdrawal.

Productivity/ output

185 to 560 m²/shift

0.5 m/min penetration; 4 m/min withdrawal.
35 to 45 percent lower in low-headroom conditions

Mix Design (depends on soil type and strength requirements)

Materials

Varied in response to soil type and needs

Usually cement but quicklime is used in clays of very high moisture content

w/c ratio

1 to 6

N/A

Binder factor

75 to 250 kg/m³

100 to 400 kg/m³ (sands and fine grained soil using cement); 200 to 600 kg/m³ (peats and organics using cement); 50 to 300 kg/m³ (soft marine clays using lime)

Volume ratio

30 to 60 percent

N/A

Reported Treated Soil Properties

Unconfined compressive strength

0.5 to 10 MPa (sands); 0.2 to 1.4 MPa (clays)

Varies depending on soil and binder, 1 to 10 MPa

Permeability

1 × 10^-8 m/s

Higher than CDM permeabilities

Young's modulus

275-700 MPa

ND

Specific Relative Advantages and Disadvantages

Full vertical mixing; capable of cutting rock and soil; boulders difficult to penetrate. Equipment very stable. Walls formed without joints or windows. Best mixing possible. Continuous production preferred (less downtime/cleaning); long, straight walls are produced

Heavy rotary heads remain at bottom of leads, improving mechanical stability of rigs, especially in soft conditions. Very little spoils; efficient mixing. Extensive R&D experience. Fast production on large jobs.

Notes

In development since 1990. Commercially viable since 1994. More than 400 projects worldwide.

Sponsored by Japanese Government and fully operational in 1980. (First application in 1981.) Offered in the United States by Raito, Inc. since 1998.

Representative References

Gularte et al.⁽¹⁶⁸⁾

Dry Jet Mixing Association of Japan; Fujita; Nishida et al.; Yang et al.^(169-172)

Classification

DRE

DRE

Company

Various (in Scandinavia/Far East). Offered in the United States by Hayward Baker, Inc.

TREVI

Geography

Scandinavia, Far East, United States

Worldwide

General Description of Most Typical Method

Shaft is rotated while injecting compressed air below mixing tool to keep injection ports clear. Dry materials are injected during withdrawal via compressed air, and reverse rotation. Requires sufficient free water to hydrate binder (e.g., sand > 15 percent; silt > 20 percent; and clay > 35 percent).

Dry materials are injected via compressed air through nozzles on shaft below mixing paddles. Binder can be added during penetration and/or withdrawal of the mixing paddles.

Special Features/Patented Aspects

Very low spoil; high productivity; efficient mixing. No patents believed current. Strong reliance on computer control. Close involvement by Swedish Geotechnical Institute

Real-time recording of drilling and grouting parameters. Use of protection bells at surface to minimize loss of vented dry binder. Needs soil with moisture content of 50 to 145 + percent to allow hydration of binder.

Details of Installation

Shafts

1 to 2 (more common). Separated by fixed (but variable) distance of 0.8 to 3.0 m.

1 to 2 (more common). Separated by fixed (but variable) distance of 0.8 to 3.0 m.

Diameter

0.5 to 1.2 m, typically 0.6 or 0.8 m

0.8 to 1.0 m (most common)

Realistic maximum depth

30 m maximum (20 m typical)

25 to 30 m

Revolutions per minute

100 to 200, usually 130 to 170

20 to 150

Productivity/ output

2 to 3 m/min (penetration); 0.6 to 0.9 m/min (withdrawal); 400 to1,000 m/shift (0.6-m diameter)

8 to 30 m³/hr

Mix Design (depends on soil type and strength requirements)

Materials

Cement and lime in various percentages (typically 50:50 or 75:25)

Dry cement (most common), lime, other cementitious materials

w/c ratio

N/A

N/A

Binder factor

23 to 28 kg/m (0.6 m diameter), typically
40 kg/m (0.8 m diameter); overall 20 to
60 kg/m (i.e., 80 to 150 kg/m³)

150 to 300 kg/m³

Volume ratio

N/A

N/A

Reported Treated Soil Properties

Unconfined compressive strength

Varies, but typically 0.2 to 0.5 MPa (0.2 to 2 MPa possible). Shear strength 0.1 to
0.30 MPa (up to 1 MPa in field)

2 to 6 MPa (sandy soil)
0.2 to 2 MPa (silts and clays)

Permeability

For lime columns, 1,000 times higher than that of the clay; for lime-cement columns, the factor is 400 to 500

ND

Young's modulus

50 to 200 × unconfined compressive strength

100 to 1000 × unconfined compressive strength

Specific Relative Advantages and Disadvantages

Same as for DJM; Swedish/Finnish research continues.

No spoil, uniform mixing, automatic control of binder quantity. System allows for possibility of injecting water during penetration.

Notes

Developed by Swedish industry and government, with first commercial applications in mid 1970s, and first U.S. application in 1996.

Developed by TREVI in Italy in late 1980s.

Representative References

Holm et al.; Rathmeyer^(173,174)

Restelli et al.; Calabresi et al.^(175,176)

Classification

DRE

DRE

Company

Various (in Scandinavia/Far East)

Hayward Baker, Inc., a Keller Co.

Geography

Scandinavia, Europe, Far East, United States

United States (but with opportunities for sister companies worldwide)

General Description of Most Typical Method

Shaft is rotated while injecting during penetration and withdrawal. Water in correct amounts is injected (low pressure) during penetration (typically) through jets in the tool head. Can be used in sand, silt or clay, hard to soft conditions.

Horizontal axis rotary drive at the end of an excavator mounted arm. Binder injected pneumatically during rotary mixing and arm movement throughout the cell.

Special Features /
Patented Aspects

Very low spoil; high productivity; efficient mixing; strong reliance on computer control. Can be used either as a soil improvement technique or direct foundation system. Current patents in United States and Mexico; Europe and other countries pending.

No special features.

Details of Installation

Shafts

Single shaft, various types of cutting/mixing blades.

Single horizontal with spiral mixing paddles around the rotating barrel.

Diameter

0.5 to 1.2 m, typically 0.6 or 0.8 m

N/A

Realistic maximum depth

30 m maximum (20 m typical)

5 m maximum

Revolutions per minute

200 to 220; 100 on down stroke if very hard soil

50 to 100

Productivity/ output

1.0 m/min finished column; 6,400 to
1,000 m/10-h shift (0.6-m diameter)

Work completed in defined cells. In excess of 700 m³/shift

Mix Design (depends on soil type and strength requirements)

Materials

Cement only

Varied in response to soil type and needs

w:c ratio

0 to 3+

NA

Binder factor

200 to 400 kg/m³. These amounts are final in situ. A correction factor is programmed into the computer to reflect waste amounts.

75 to 250 kg/m³

Volume ratio

N/A

0 to 5 percent

Reported Treated Soil Properties

Unconfined compressive strength

Depending on binder amount and soil type, range is 0.6 to 6.0 MPa. Generally, in clay with 400 kg/m³ yields 3.0 MPa design strength.

1.0 to 3.0 MPa (sands); 0.1 to 1.0 MPa (clays)

Permeability

400 to 500 times the k of the clay

1 × 10^-7 m/s

Young's modulus

50 to 200 × unconfined compressive strength

50 to 150 ksi

Specific Relative Advantages and Disadvantages

Can be used in wide range of soils, hard, soft, dry, or wet. Binder and water amounts can be continuously changed during installation of column. Additives (e.g., accelerators or retarders) can be introduced through the water at specific depths.

Low quality mixing usually done at high treatment ratios to support uniform loads over soft or organic soil.

Notes

Patented by LC Technology, Inc. and jointly developed by Swedish foundation contractor Hercules Gundeläggning AB. First commercial applications in Sweden in 2003

In development since 2003. Commercially viable since 2005.

Representative References

Gunther et al.; Eriksson et al.^(177,178)

Burke et al.⁽³⁰⁾

Classification

WRS

Company

Schnabel Foundation Company

Geography

North America

General Description of Most Typical Method

Multiple discontinuous augers on a semi-fixed, crane supported lead. Augers rotate in opposite directions. Most of the binder slurry injected on the down stroke to create panels. Air injected during mixing in clays.

Special Features/Patented Aspects

Used primarily for structural cutoff walls as part of an earth retention system. Double stroking frequently done; 75 to 80 percent of the wall is exposed during excavation.

Details of Installation

Shafts

Single shaft; various types of cutting/mixing blades.

Diameter

0.5 to 1.2 m, typically 0.6 or 0.8 m

Realistic maximum depth

30 m maximum (20 m typical)

Revolutions per minute

200 to 220; 100 on down stroke if very hard soil

Productivity/ output

1.0 m/min finished column; 64,00-1,000 m/10-h shift (0.6-m diameter)

Mix Design (depends on soil type and strength requirements)

Materials

Cement only

w/c ratio

0 to 3+

Binder factor

200 to 400 kg/m³. These amounts are final in situ. A correction factor is programmed into the computer to reflect waste amounts.

Volume ratio

N/A

Reported Treated Soil Properties

Unconfined compressive strength

Depending on binder amount and soil type, range is 0.6 to 6.0 MPa. Generally, in clay with 400 kg/m³ yields 3.0 MPa design strength.

Permeability

400 to 500 times the k of the clay

Young's modulus

50 to 200 × unconfined compressive strength

Specific Relative Advantages and Disadvantages

Economical proven system for structural cutoff walls. Special mixing tools designed for penetrating very dense, coarse-grained soils. Crane attachment allows flexibility in positioning mixing tools. High mobilization costs.

Notes

Used for excavation retention system since 2000

Representative References

Anderson; Porbaha et al.^(15,10)