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The Soilcrete Jet Grouting Process

Brochure 67-03 E


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Contents

History ................................... 3

Soilcrete Jet Grouting Process .......... 4

Process Variations ............... 6

Construction Forms ............ 7

Construction Sequences ..... 8

Stabilisation ......................... 10

Sealing..................................

Addresses ............................ 12


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With the aquisition o a licence in1979 or the jet grouting processand the introduction into Germanyunder the trademark Soilcrete ,Keller Grundbau entered into anew eld o soil stabilization.

Soilcrete History

Small scale underpinning works were thebeginnings o an unusual way o jet grouting.To reach todays state o the art, additionaldevelopment was necessary.

The process was modi ed to

suit di erent types o soils.

The application was developed

step by step to provide solutionsto a variety o problems.

Equipment was developed

and improved.

The Soilcrete

-technique hasbeen enhanced constantly.

This brochure reports on the state o the Soilcrete -technique today.


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The name Soilcrete derives rom theconcept soil to concrete a ormo soil with a concrete consistence, adescription that characterizes the typeo soil stabilization.

Soilcrete Jet Grouting Process

The jet grouting processThe jet grouting process Soilcrete isrecognized as a cement soil stabilization. Withthe aid o high pressure cutting jets o water or cement suspension having a nozzle exitvelocity 100 m/sec eventually air-shroudedthe soil around the borehole is eroded.

The eroded soil is rearranged and mixedwith the cement suspension. The soil-cement mix is partly ushed out to the topo the borehole through the annular spacebetween the jet grouting rods and the bore-hole. Di erent geometrical con gurations o Soilcrete -elements can be produced.

The erosion distance o the jet variesaccording to the soil type to be treated,the kind o Soilcrete -process and the

jetting uid being used, and may reachup to 3.5 meter.This technique is regulated by EuropeanStandard EN 12716.

ApplicationsIn contrast with the conventional groundstabilisation methods Soilcrete may beused or stabilization and sealing o all kindo soil ranging rom loose sediments to clay.This applies also or non homogeneous soil

ormations and changing soil layers, includingorganic material. So t rock ormations havealso been treated by Keller or example

sandstone with weak grain texture.

Application limits or grouting techniques

Grain size [mm ]

Clay Silt

P a s s i n g

b y w e

i g h t

[ % ]

Sand Gravel Coubles

0.002 600.006 0.02 0.06 0.2 0.6 2.0 6.0 20

100

80

60

40

20

Mortar

Cement Suspension

Ultra Fine Cement

Silicate Gel [hv]

Sodium Silicate Solutions [lv]Synthetic Solutions

Soilcrete Jet Grouting

0economical

nv = low viscoushv = high viscous

uneconomical


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The Soilcrete - propertiesSoilcrete acts in the ground according tothe speci cation either as a stabilization or as a sealing structure. A combination o both properties is increasingly required.The compressive strength o Soilcrete ranges rom 2 to 25 N/mm 2 and isdetermined by the cement content andthe remaining portion o the soil in theSoilcrete mass. The sealing e ect o Soilcrete against water ingress is achievedby selecting a suitable grout suspension andi necessary by the addition o bentonite.The type and quantity o the injected groutmaterial as well as the kind and volume o the remaining soil particles in the Soilcrete mass guiding the sealing properties.

Depending on the nature o soils, Soilcrete -cut-o s are able to reduce the coefciento permeability by several decimal powers.High quality requirements in respect o the degree o sealing e ect necessitateextensive production e orts. For manyapplications both the strengthening andsealing characteristics o the Soilcrete -elements are used. The selected suspen-

sions need to be composited accordingly.

Soilcrete-sealing mixturestested in a laboratory

Soilcrete-pump and control station

Soilcrete-cubaturesorming a rm contact

with any kind o oundation orms

0.002 0.06 2.0 7 14 21 28 35 4260

100

75

50

25

0

100

50

0

Passing by weight [%]

Grain size [mm ] Setting time [days]

Silt Sand

non-cohesivesoil

cohesive soil

Gravel

Compressive strength in % o the nal strength

Compressive strenght o Soilcrete Development o Soilcrete -strength

Type o soil Silt Sand Gravel

Compressive strength [N/mm] 5 10 < 25

Soilcrete

Foundation


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The basic geometrical orm o Soilcrete -elements is created through movementso the drill rods:

Pulling o the drill rods without

rotation resulting in panels i several jet nozzles are usedmultiple panels may be produced.

Pulling and swivelling

create segments.

Pulling and rotating create

complete columns.

Soilcrete Construction Forms

Exposed test eld with several Soilcrete-disksor a sealing slab

Panel wall with sealing slab Underpinning elements

Sealing slabs

Panel walls

Box walls

Column walls

Deep oundation

Exposed Soilcrete-elements o an underpinning wall in sandy soils

Soilcrete basic ormsThe Soilcrete basic orms may be arrangedand combined in any way to orm each typeo element.

Interlinked Soilcrete -elements

Interlinked bodies constructed rom uni orm

elements

Column

One sided

Twin sided

Lamella

A = Quarter ColumnB = Hal ColumnC = Complete Column


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Soilcrete Construction Sequenses

Soilcrete -site installations consist o storagecontainers, silos and a compact mixing andpumping unit. Several high pressure hoseconnections and control cable lines connectthe pumping unit with the Soilcrete drillingrig at the installation point. The mast lengtho the rig varies rom 2.0 m in cellars or sha tsand up to 35.0 m in open areas. The borepoints are normally located in small trenchesequipped with sludge pumps. From there theexcess material, water-cement-soil mixture ispumped to setting ponds or tanks.

Small drilling rigsmanu actured by Keller provide access tocon ned working places

1 Drilling

Drill rods equipped with jetnozzle holder and drill bit areused to drill the jet grouting holedown to the required depth.Normally the jet grout mixture isused as drill fushing to stabilizethe borehole during the drillingoperation. In masonry and

concrete, special drilling bits areused.

2 Jetting

The disolution o the graintexture with a power ul fuid jetstarts at the lower end o theSoilcrete -element. The excesswater soil cement mixture isremoved to the sur ace throughthe annular space between drillrod and bore-hole wall. The pre-

selected production parametersare constantly monitored.

3 Grouting

For all Soilcrete -variationscement suspension is injectedunder pressure simultaneouslywith the erosion o the soil. Theturbulences caused by the jettingtechnique results in the uni ormmixing o the grout with thesoil within the treatment zone.

Until the grout in the Soilcrete

-elements starts setting hydro-static pressure in the boreholeis kept by back lling grout intothe hole rom time to time.

Grout suspension

Pump

Storage tank

WaterAir

Backfow recycling


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9

Optical and manual checking as well as con-trols and tests according to the requirementslaid down in the European standard EN 12716ensure quality work manship.4 Extension

Soilcrete -elements o each ormmay be constructed resh on

resh as well as resh against rmand combined and connected ina variety o ways. The workingsequence ollows the technicalrequirements and the conditionso the structure to be treated.

Recording unit M5

Important constructionparameters may beelectronically recorded

Core recovery romSoilcrete-elements

Time

[sec]

Process: Soilcrete-D- Process ( . . )Inventar: Site: Lot: Point: Re . No.: Date: . . Time: : : Interval: secWeight:Legend:

Flow

[l/min]

Groutpressure

[bar]

Drillingpressure

[bar]

Depth

[m]

Revolutions

[rpm]

Progress

[m/min]

Total time: . min Max. depth: . m Length column: . m

0 50 100

1000

2000

3000

4000

5000

6000

7000

8000

00 250 5000 250 5000 100 20020 0 200 5 10

Process monitoringUp to 12 di erent parameters or theconstruction o Soilcrete -elements maybe recorded and used by the engineer-in-charge o supervision and control.

Cement/Bentonite

Mixer


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Soilcrete Applications

Soilcrete or stabilisationUnderpinning work or adjacent construction pits is one o the main taskso soil stabilisation ollowed by oundation modi cations and restoration.Soilcrete opens new ways or tunnel constructions in loose soils.

Underpinning by meanso low de- ormation grav-ity walls sometimes alsoused as a ground watersea-page barrier, may besa ely constructed even

rom con ned workingareas.

Soilcrete -tunnelprotection is mainlyconstructed in loosesoils below or close toendangered structures,sometimes with theaim o reducing thegroundwater ingress intothe tunnel excavation.

Underpinning Tunnel protection

Foundation restoration Soilcrete Horizontal

Foundation modifcation Sha t supports

Deep oundation Earthpressure relie

Historical buildings maybe endangered in theevent o settlementsoccurring. Soilcrete

provides a sa e ounda-tion with the maximumstructural protection.

Horizontal Soilcrete -columns protect tunneldrives in loose soil

ormations. They are

constructed rom workingaces and are horizontalor slightly inclined.

Changes in utilisations ormodi cations o buildingso ten require an enlarge-ment or alteration o the

oundation. Soilcrete is an economical andfexible solution or thistask.

Sha ts with intersectingSoilcrete -columnsare constructed i avibration ree installationis required and/orthe sha ts enter intogroundwater bearingstrata.

Soilcrete is usedor new oundations

which require specialcare inview o nearbyexisting structures such

as historical buildingsand other shock-sensitive constructions.

Structures exposed toearth pressures, suchas historical walls,abutments, avalanchegalleries, steeps lopes

protections or quay wallsmay be relieved by theaddition o or connectionto a statically calculatedbackup Soilcrete body.


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Soilcrete or sealingBuilding pit walls constructed o de ormation and ground water resistant Soilcrete -underpinning elements, combined with low permeable Soilcrete -slabs enablesthe execution o deep building pits without the need or large scale ground water lowering. Environmental sa e mineral binder materials are used or Soilcrete .

Soilcrete -panel wallsto cut o groundwater are used belowroads and buildings, orcrossing pipelines and tosubdivide building pitsinto di erent excavationsections. According to

the sealing requirements single or multiple panels maybe constructed.

For small building pitsand sha ts with reducedwidth Soilcrete -slabsare used as preventionagainst the water upli tpressure, reducing therequired depth o slabsnormally required to re-sist the hydrostatic upli t.

Panel walls Vault slabs

Column walls Sealing cover

Dam sealing Joint sealing

Sealing slabs Groundwater exits

In the event o highermechanical strain byshear orce, danger o undermining or o a

high impermeabilityrequirements, cut o walls o intersectingSoilcrete -columnsmay be constructed.

The Soilcrete -coverprotects the groundwaterbelow buildings againsta ects rom construction

activities and old toxicwaste de-posits.

Soilcrete may be usedto repair dam cores orenlarge cut-o walls inor below dams.

For sealing o joints be-tween piles, sheet pilesor other constructionparts in the ground theSoilcrete -wing-jet isapplied.

Soilcrete -sealing slabsare constructed by meanso overlapping columnswithin an upli t proo depth. The sealing slabs

may be connected to anykind o vertical sealingsystems.

Sealing walls are o tenused as temporaryground water barriers.The reinstatement o the permeability may

be reached using theSoilcrete -process towash out the bindermaterial rom prede ter-mined sections.


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A company of Keller Group plc

Keller Holding GmbHHead Ofce and Overseas Division

Kaiserleistrae 4463067 OffenbachGermanyTel. +49 69 8051-0Fax +49 69 8051-244E-mail: [email protected]

www.KellerGrundbau.com

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