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desired, and to effect grouting operations intended with these materials. Inthe 35 years or so since those specs were written, the chemical groutingindustry has expanded greatly, and the exposure of engineers in general to

grouting data has increased vastly. Nonetheless, so long as we avoidperformance specications, the 1968 publications remain a good startingpoint for most chemical grouting jobs.

The major section titles in the guide specs are General (or Scope of Work), Materials, Equipment, Supervision, Application, and Payment forWork Performed. How these topics may be effectively handled is illustratedin the excerpts from actual job specications which follow.

The opening paragraphs of a set of specications should broadlydene each phase of the work to be done, so that contractors extras are keptto a minimum. The rst three paragraphs of a Corps of Engineersspecication under the heading Advancing and Casing Holes in Over-burden and Grouting read as follows:

1-1 GENERAL

1-1.1 Scope

This section covers advancing, casing and washing grout holes;making grout connections; furnishing, transporting, mixing andinjecting the grout materials; care and disposal of drill cuttings andexcavated overburden, waste water and waste grout; cleanup of theareas upon completion of the work and all such other operations asare incidental to the drilling and the grouting.

1-1.2 Program

The work contemplated consists of grout stabilization of loose soilareas and voids, the approximate locations, limits and details of which are indicated on Drawings Nos. 0-PHG-84/2 and 3. Graphiclogs of overburden materials are included as Drawing No. 0-PHG-84/6. Typical void grouting details are included as Drawing No.0-PGH-84/4. The program shown on the drawings and describedherein is tentative and is presented for the purpose of canvassingbids. The amount of drilling and grouting will be determined by the

Contracting Ofcer.1-1.3 Procedures

Grouting mixes, pressures, the pumping rate and the sequence inwhich the holes are drilled and grouted will be determined in theeld and shall be as directed.

yright 2003 by Marcel Dekker, Inc. All Rights Reserved.

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The same specication under the heading Drilling Holes ThroughReinforced Concrete Pipe Joints and Chemical Grouting reads as follows:

2-1 GENERAL

2-1.1 Scope

The work covered by these specications includes furnishing alllabor, materials, supervision and equipment necessary for thechemical grout stabilization of and the cutoff of water owingthrough loose soil and voids in the immediate area surroundingleaking joints of the sewer within the limits shown on the drawings.The work includes diversion of surface runoff and wastewater ow;cleaning of the sewer, cleanout of joint annulus; drilling andcleaning of grout holes; furnishing, transporting, mixing and

injecting the chemical grout at sewer joint, cleanout and patchingof the nished grout holes and sealing of the joints; clean-up of thesewer and such other operations as are incidental to the drilling,grouting, and sealing. The lengths of the various size reinforcedconcrete pipe sections of the sewer from which stabilizationchemical grouting and joint scaling will be conducted are as follows:

By way of contrast, specications for grouting under a damspillway in the Midwest were far less detailed:

ITEM 4DRILLING AND GROUTING

4. 01Scope of Work

a. Location and Type of Work . The work includes but is notlimited to the following:

Drilling, casing where necessary, pressure testing as required,

LocationDiameter(inches)

Normal jointspacing (feet)

Number of tongue and

groove jointsto be grouted

INCO Industrial ComplexM.H. 3 to M.H. 12 66 4* 491M.H. 1 to M.H. 3 60 4* 50

*The listed normal joint spacing is based on information from visual inspectionand is included for the information of the bidder but does not guarantee thatadditional joints at closer spacing may not be encountered occasionally.


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and pressure grouting using chemical grout, the stratum of densesand which exists at about elevation 720 underlying the spillwaysection of Dam near Indianapolis, Indiana.

b. General Program . The program for drilling and for pressuregrouting is tentative. The extent of the program will be determinedby the conditions developed at the site.

Holes for pressure grouting are designated as A, B, orC (see Contract Drawing 5A-1). Holes designated as A holeswill be grouted rst. The number and spacing of B and Choles, and the pressures and gel times to be used, will depend uponthe results of water pressure or other tests, and the results of theactual grouting operations conducted for the A holes. Allpressure grouting will be accomplished prior to any excavation

for the spillway sections.The amount of drilling and grouting that will be required isapproximate and the Contractor shall be entitled to no extracompensation above the unit prices bid in the schedule for thisspecication by reason of increased or decreased quantities of drilling and grouting work required, the time required, or thelocations, depth, type or nature of foundation treatment.

Specications written by large public agencies are generally verydetailed, as illustrated by a 1987 specication for sealing leaks in a subwaysystem:

3G1.1 SCOPE

(a) The work shall include the furnishing by the contractor, of allsupervision, training, labor, materials, tools and equipment and theperformance of all operations necessary for the waterproonginjection grouting work indicated in the Contract Drawings,specied herein, and/or as directed by the Engineer.

(b) The work consists of the injection of liquid chemical groutsinto active and inactive leaks through concrete cracks, joints orholes located in roofs, sidewalls, oors, rooms, beams and other

locations in the 33rd Street line designated in the document entitledLeak Locations incorporated into, and made a part of thiscontract, and in all other areas designated by the Engineer andlocated within the limits of the Contract.

(c) The work shall be performed in a skillful and workmanlikemanner with special care taken to prevent damage to existingstructures, drains and utility lines. Damage caused by improper


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work procedures or failure to maintain drains, lines, equipment orstructures shall be the responsibility of the Contractor.

(d) Documentation of the work shall be performed by theContractor, including both daily work Reports and color-codedmarkings of grouting locations marked neatly on the concretesurface adjacent to each leak repaired, at the time of completion of the repair to indicate grouting pass number, grout used, groutingcrew identity and date of repair. Contractor shall submit hisdocumentation and coding scheme for approval.

(e) In order to judge performance, all sealed work shall beinspected by the contractor and the engineer within 3 days after agreater than 12 inch rainfall in one 24-hour period during theconstruction phase. The work priorities will be adjusted accordingto the results of the survey, at the direction of the engineer.

(f) It is estimated that approximately 34,400 lineal feet of cracksand joints may require treatment.

Recent specications for grouting jobs often include requirements forbidder qualication, as additional assurance of satisfactory low bidderperformance. The following sections from a 1987 document show details:

3G1.2 CONTRACTOR QUALIFICATIONS

The actual grouting work specied herein shall be performed by a

qualied Contractor with a minimum of ve (5) years direct,continuous and recent experience in performing waterproongchemical grouting work in similar conditions on at least six (6)different projects.

3G1.3 FIELD SUPERVISION QUALIFICATIONS

Field supervision shall be provided by a Grouting Superintendentwith at least four (4) years recent experience in waterproongchemical grouting work and who meets the above projectexperience requirement, by Journeyman Grouting Foremen withat least two (2) years recent experience with the equipment andchemical grouts specied in applications similar to the proposedproject, and by Apprentice Foremen who have at least six (6) weeksfull-time experience in waterproong grouting work under thedirect supervision of a qualied Journeyman Grouting Foreman.

The same specication also called for submission of qualication dataas pre-bidding requirement.


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Specications for grouting materials are generally very detailed, listinggeneric names, trade names, and manufacturers. Specs written by publicagencies must either permit the use of equal materials or be prepared to

defend legally their decision not to permit bidding on alternates. Thespelling out of grout properties in great detail helps ensure those desired andvirtually eliminates the offering of alternate materials. This situation iscommon to all areas where spec writers are requesting specialty products. Asknowledge of the products and their use grows, the specications becomemore oriented to properties and performance rather than trade names andformulas.

A Corps of Engineers spec starts with a general statement but quicklybecomes very specic:

1-3.3 Chemical Grout Materials.

1-3.3.3 General. The void stabilization materials shall be propor-tioned y ash with chemical grout and a catalyst system. Thechemical grout used shall have a documented service of satisfactoryperformance in similar usage. All materials shall be delivered to thesite in undamaged, unopened containers bearing the manufacturersoriginal labels. The materials shall be equal to chemical grout AM-9with recommended catalysts and other materials as manufacturedby the American Cyanamid Company and conforming to thespecications described hereinafter.

Succeeding paragraphs cover in detail the basic chemical grout,catalyst, activator, inhibitor, ller, and additives.

A less restrictive paragraph appears in California specs for drilling andgrouting test holes at a dam and reservoir:

(5) Chemical Grout. Chemical Grout shall be a mixture of variouschemical compounds which gel or solidify in a given time aftermixing. Given gel or solidication time shall range between twominutes and 60 minutes. The viscosity of the grout mix shall be lessthan 1.5 centipoises before gelling or solidication. The chemicalsused shall be so proportioned and mixed as to produce a chemicalgrout that contains no solids, may be pumped without difculty,and will penetrate and ll the voids in the soil mass and form a gelor solid lling which will be of the required strength, be stable andimpermeable.

A far more liberal set of specications for a tunnel in Asia merely sayschemical grout including acrylamide, monosodium phosphate, sodiumsilicate, calcium chloride or other suitable approved chemical grout.


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A New York City Transit specication listed satisfactory materials indetail:

3G2.0 GROUT MATERIALS

3G2.1 GENERAL

Two different kinds of chemical waterproong grouts are intendedto be used for sealing concrete cracks and joints, to be selected forapplication at specic locations based on the nature of the crack or joint in relation to the grouts properties. Polyurethane grouts areintended for use in running water conditions or where moderate tolarge joints and cracks with active water leakage are encountered,and otherwise as directed by the Engineer. Acrylate grouts areintended to be used where inactive leaks are encountered, in ne

cracks and otherwise as directed by the Engineer. All grout usedshall have a successful history of application for at least four (4)years under conditions similar to the current project.

3G2.2 POLYURETHANE GROUT

Polyurethane grout supplied shall be water-reactive liquid poly-urethane base solutions which when reacted expand by foaming toat least seven (7) times the initial liquid volume and when setproduce a exible, closed void solid resistant to degradation by wetand dry cycles and chemicals found in concrete construction.Specic waterproong grouts meeting these requirements aremarketed by the following manufacturers. . . .

3G2.3 ACRYLATE GROUT

Acrylate grout used for waterproof grouting shall be watersolutions of acrylate salts which, when properly activated andcatalyzed, react in a controlled set time to form a exible,permanent gel. Specic waterproong grouts meeting theserequirements are marketed by the following manufacturers. . . .

(For each class of grout, two acceptable manufacturers and products werecited.)

Specications for equipment have also in the past been very detailed,primarily to avoid the problems that would occur if bidders intended to usecement grout pumps for chemical grouting. Most often, the described detailscover a page or more, with separate paragraphs dealing with capacity(pressure and volume), materials of construction, number of pumps, drivesystems, and control systems including gel time control, pressure andvolume control, and systems to prevent overpressuring or inadvertent


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recycling (see Chap. 14) . The following paragraph from a specication ondam foundation grouting is one of the least detailed ways to preclude the useof batch systems:

d. Grouting Equipment . All equipment used for mixing andinjecting grout shall be furnished by the contractor and shall bemaintained in rst class operating condition at all times. Theequipment will be of proportioning or two solution type, and willinclude such valves, pressure gages, pressure hose, supply lines,pipes, packers, jacks and small tools as may be necessary to providea continuous supply of chemical solution at required pressures andvolumes. [At this point, and at required gel times could have beenadded.]

A complete detailing of equipment was done in this excerpt from a 1987specication:

3G3.1 EQUIPMENT

(a) General(1) The Contractor shall supply all equipment, including pumps,containers, hoses, gages, packers, drills, bits, scaffolds, compres-sors, generators, vacuums, accessories, and all other items requiredto perform the work and accomplish the goals outlined in theSpecications.(2) The equipment shall be of a type, capacity, and mechanical

condition suitable for doing the work in an effective and efcientmanner. All equipment including all power sources, cables,chemical containers, scaffolds, and anything used in the perfor-mance of the work, shall meet all applicable safety and otherrequirements of Local, State, and Federal ordinances, laws,regulations, and codes.(3) All equipment shall be maintained in excellent workingcondition at all times. Sufcient spare parts and tools shall bemaintained on the job to provide for immediate (1 hour) repairs of essential operating items.(4) Each grout crew shall maintain its own equipment itemsrequired herein in order to operate independently of, and separatedfrom, other grout crews.

(b) Pumping Units(1) The Contractor shall supply separate pumping units, includingseparate chemical containers, hoses, and all other accessories forinjection of polyurethane grout and acrylate grout.

http://dke78_ch14.pdf/http://dke78_ch14.pdf/

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(2) Pumps shall be capable of continuous injection of the liquidgrout under variable pressures up to a maximum pressure of 2,000 psi and at ow rates of at least 5 uid ounces per minute at

high pressure (2,000 psi) and ow rates of at least 14 gallon perminute at pressures of 500 psi and lower, and in accordance with the

manufacturers recommendations and under the direction of theEngineer. Pumps may be electric, air, or hand driven provided thatrapid changes in pumping rates and pressures can be obtained bythe pump operator without effecting the mixture of the grout beinginjected and without stopping the pumps.(3) Pumping Units shall be made of materials compatible with thechemicals being used, and shall be equipped with necessary hoses,chemical containers, gages, ttings, packers and other accessoriesrequired to inject the grout properly. Seals and joints shall be suchthat no grout leakage occurs and no air is aspirated into the injectedgrout.(4) Grouting Units shall be so arranged that ushing can beaccomplished with grout intake valves closed, ushing uid supplyvalves open, and the pump operated at full speeds.(5) Pumping Units shall be equipped with accurate pressure gagesat the pump and near the injection point. Gages shall be accurate to5% and shall be periodically checked for accuracy against new,undamaged or calibrated gages. Damaged or inaccurate gages shallbe replaced immediately. Pumping units shall not be operated

without properly operating gages. Replacement gages shall be onhand at all times.(6) Hoses and ttings shall have maximum safe operating pressureratings and dimensions as recommended by the manufacturer andunder the direction of the Engineer.(7) Suitable mixing and holding tanks shall be supplied with eachgrouting unit to permit continuous pumping at maximum pumpcapacity. Tanks shall have satisfactory covers and shall be stableagainst tipping under normal usage.(8) Descriptions of pumping units for both polyurethane groutand acrylate grout shall be submitted for approval by the Engineeras required in these specications before starting the actual groutingwork. Written approval of the pumping units shall be received fromthe Engineer by the Contractor before actual grouting is started.

(c) Polyurethane Grout PumpsGrout pumps used for polyurethane grout injection shall be eithersingle or double pump type as recommended by the grout


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manufacturer. Where double pump types are used, they shall havethe same capabilities as required for acrylate pumping units, butshall properly accommodate the more viscous materials used for

polyurethane grouts. In no case shall polyurethane grout pumps beused for injection of acrylate materials, or acrylate grout pumps beused for injection of polyurethane grouts, in the same day norwithout thorough cleaning, disassembly and appropriate modica-tion nor written notication to and approval by the Engineer.Pumps shall be arranged and operated in a manner consistent withthe grouts injected and the grout manufacturers recommenda-tions.

(d) Acrylate Grout PumpsAcrylate grout pumping units shall consist of two, parallel highpressure, positive displacement pumps with parallel hoses leading toa mixing chamber or Y at the packer. Pumps shall be equippedwith check valves to prevent the back-ow of one grout componentinto the lines of the other component.

(e) PackersPackers which are specically designed for the grouting operationshall be supplied and used capable of safety sealing and packinggrout holes drilled into concrete and injected at pressures of up to3,000 psi, and as recommended by the manufacturer of the grout.Packers shall be of the removable type such that the drilled hole canbe cleaned and patched to at least 3 inches deep.

(f) DrillsHand drills capable of drilling small diameter holes of 12 to 1 inch indiameter in concrete shall be supplied and operated. The followingtwo types of drills shall be supplied for each grouting crew: (1)Rotary percussion capable of drilling up to 18 inches deep inunreinforced concrete; (2) Rotary ushing type with diamondcoring bits capable of drilling up to 24 inches deep in reinforcedconcrete. Drills shall be supplied with bits of a diameter and length

consistent with packer requirements and hole lengths needed for thedrilled holes to intersect the target crack or joint as specied.Damaged or worn bits shall not be used. Backup drills and bits shallbe supplied in sufcient numbers so that two drills of either type canbe used simultaneously.

Specications sometimes will have a separate paragraph dealing withsupervision, as for example, this paragraph from a dam grouting spec:


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(e) Procedures. Supervision of all phases of the contract shall beunder the direct control of the Engineer. The Engineers respon-sibility includes but is not limited to location of holes, drilling of

holes, re-drilling of holes, procedures, methods of grouting, mixingof grout, and maintaining complete records of the groutingoperation including cost items.

More often it is inferred by such phrases as as directed by theEngineer, in a manner approved by the Engineer, etc.

Sometimes a few words hidden away in other sections remove allengineering decisions from the contractor. In a detailed spec for grouting atunnel in Hong Kong, the following paragraph appeared under Section 6.11,Grouting Procedure : The grouting methods, mixes, pressures and pumpingrates together with the sequence in which the holes are drilled and grouted

will be determined by the Engineer.Sections of specications dealing with application may be very brief if a performance criterion is used; otherwise the scope of the contractorprocedural responsibilities must be completely spelled out. These will varyconsiderably from job to job. A general guide appears in Ref. [1], excerptedhere:

APPLICATION

The application of chemicals shall be under the direct supervision of the grouting engineer. Application shall be understood to include:

a. Placement of grout holesholes may be placed by rotary orpercussion drilling, driving or jetting (using water or air), dependingon the formation and its response to each method (see Note 18).Casing must be provided for caving formations (the drive pipe or jetpipe may be used for this purpose). Casing must also be providedfor formations which will not otherwise permit proper seating of downhole packers. Holes must be placed with sufcient accuracy toinsure that planned overlapping of grout from adjacent holes canoccur.b. Grout patternthis includes the geometric layout of all theholes, the sequence in which each hole is placed and grouted, andthe vertical dimension and sequence of grouting the lifts (stages) foreach hole. The geometric layout of holes, both in plan or in prole,should be completely planned prior to the start of grouting, andsubmitted to the owner for approval (or information).c. Field testsprior, during and after the completion of thechemical grouting operation, eld tests should be performed andrecords kept to determine the effects of grouting. Such tests should


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be performed in accordance with generally accepted procedure (seeNote 19) subject to approval of the owner or his engineer. Thegrouting engineer will be responsible for obtaining or constructing

adequate test instrumentation and keeping records of eld data fortesting them during and after grouting.d. Pumping pressuresmaximum value of pumping pressure atthe collar of the hole is (see Note 20).e. Concentration of chemical groutthe concentration of chemi-cals mixed in the tank (computed as a dry weight percentage of thetotal solution weight) shall generally be (see Note 21). Inno case shall the concentration be less than , and it may goup as high as .f. Induction periodControl of the induction period is theresponsibility of the grouting engineer. Control should be donemechanically, through the pumping system controls, using theminimum number of stock solution variations (none, if possible).Wherever feasible ground water from the site at the site temperatureshall be used to prepare the stock solutions, to eliminate differencesin tank and underground gel times (see Note 22).g. Gel checksa sampling cock placed between the Y-tting andthe grout hole or pipe shall be used for checking both inductionperiod and gel strength. Such checks shall be made every time theinduction period is changed, or at least once every ve minutesduring long pumping times, and at least once during every grouting

operation of less than ve minutes (see Note 23).Notes :

No. 18 Delete any methods not compatible with local conditions.No. 19 Pertinent eld tests include drop tests, pumping tests and

piezometer installations. Methods of performing such testsmay be found in Theory of Aquifer Tests, U.S.Geological survey Water-Supply Paper 1536-E, 1962, andthe U.S. Bureau of Reclamations Earth Manual(Appendix pages 541 to 562) and other technical publica-

tions. If desired, specic test methods may be specied inthis paragraph.

No. 20 Specify here the maximum allowable pumping pressures, asdetermined by structural safety considerations. In general,these pressures can be as high as permissible values forcement grouting.


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No. 21 Specify here grout concentrations desired and specify alsothe minimum and maximum percentage limits of each of the materials involved.

No. 22 Mechanical control will not be possible for batch systems.No. 23 Gel checks for batch system need be made only at the startof the grouting operation, or if chemical concentration inthe tanks are changed.

The specics of grout injections are spelling out very clearly in thefollowing section from a New York City specication:

Step (5) Grout Injection. Injection of the selected grout shallcommence immediately after installation of the packer and shall bedone using the equipment, materials, and procedures speciedelsewhere in this Paragraph 3G3.0. Pumping shall proceed as longas all of the following conditions are fullled: (a) grout is enteringthe crack or joint; (b) the observable loss of grout returning fromthe crack is estimated to be less than 50 % of the volume of acrylategrout or less than 25 % of the volume of polyurethane grout beingpumped; (c) damage is not being done to the structure; (d) the totalvolume of grout injected in the current episode in the hole does notexceed ve (5) gallons for acrylate grout or two (2) gallons forpolyurethane grout; (e) the grout has not extended for more thanve (5) feet along the crack or joint away from the grout hole; or (f)the Engineer has not indicated that grouting should stop.

Specication writers often nd it necessary or desirable to dene in theapplication section terms which are generally used by grouters. Thepurpose is to avoid ambiguity and misunderstandings of procedures whichare done differently in different geographic locations. For example, specwriters for a Hong Kong tunnel found it desirable to dene groutingmethods:

6.8 The following grouting methods, inter alia, shall be adopted asdirected by the Engineers Representative:

(a) the closure method of grouting, involving grouting in anadditional hole located midway between two previously drilledand grouted holes;

(b) packer grouting, consisting of rst drilling a hole to its naldepth and then grouting from the bottom upwards in stepsdened by a packer set at successive higher elevations;


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Company caused delays if contractor is given 16 hours or morenotice to discontinue the work for one or more succeeding days.3.4 Item 4 Grout material costs which shall include the invoice

cost freight and sales tax of all chemical grout material required inexcess of the material furnished by Company. Company will pay forall material required to produce a minimum of 4,000 gallons of jelplus any additional material actually injected as directed byConstructor.

An East Coast public agency dened payment for tunnel sealing work asfollows:

(b) Payment: Payment shall be made on the following basis:

(1) Mobilization and Demobilization: Payment for mobilizationand demobilization will be made at the Contract Lump Sumprice of $100,000.00 as measured and specied in 3G5.0(a) (1)above.

(2) Cracks Treated with Acrylate Grout: Payment will be madefor cracks treated successfully with Acrylate grout at theContract Unit Price per lineal foot as measured and speciedin 3G5.0(a) (2) above.

(3) Cracks Treated with Polyurethane Grout: Payment will bemade for cracks treated successfully with Polyurethane groutat the Contract Unit Price per Lineal Foot as measured and

specied in 3G5.0(a) (3) above.(4) Acrylate Grout: Payment will be made for Acrylate Groutat the Contract Unit Price per gallon based upon thedocumented actual cost to the Contractor Plus 5 % asmeasured and specied in 3G5.0(a)(4) above.

(5) Polyurethane Grout: Payment will be made for PolyurethaneGrout at the Contract Unit Price per gallon based upon thedocumented actual cost to the contractor plus 5 % as measuredand specied in 3G5.0(a) (5) above.

These brief statements followed very detailed sections on quantitymeasurement.

The French Association of Underground Construction publishes thedocument Recommendation for the Use of Grouting in UndergroundConstruction (reproduced in translated form as Appendix B of Ref. [3]).This document should prove very useful to those who are writing chemicalgrouting specications.


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21.3 SUPERVISION OF GROUTING

The term supervision as used in typical domestic grouting specicationsgenerally refers to all mechanical operations connected with procuring,storing, mixing, catalyzing, and placing grout. Only in performance-typespecications is supervision also responsible for the results of the groutingoperation. In either case, however, a good supervisor should have theexperience, knowledge, and desire to make his/her own evaluation of thegrouting design in terms of its probable effectiveness specically as relatedto the eld operations to be controlled. Among the many factors to beconsidered are the following:

1. Is the proposed solidied volume of soil spatially dened? Howmuch grout will be placed in that volume? Is that amountconsistent with the percent voids in the formation?

2. Are the grout holes laid out in plan and prole? Do the holes enterthe zone to be grouted? Have a sequence and time schedule of holeplacement been selected?

3. Is the method of placing holes consistent with the formation andthe depth and accuracy of placement required?

4. Has a grouting schedule been established for each hole, includingstage length and grout volume?

5. Have pumping pressure limitations been established? Are theseconsistent with placement of reasonable volumes while avoidinguplift or fracturing?

6. Has a grout been selected? Are its properties consistent with theability to penetrate the formation and provide needed strengthand gel time control?

If all these questions can be answered afrmatively, while it does notguarantee success, it does at least indicate that the design has been wellthought out. Questions that have not been considered or answered prior tothe start of the eld work will have to be answered while working. This maycause delay and inefciency, and decisions which should ahve been made indesign must sometimes be made in the eld by the supervisor in order tokeep the job moving. A prestart evaluation by the supervisor may avert thissituation.

The factors suggested for consideration are but the major ones, andnot necessarily all of those. A separate check list should be made by thesupervisor for each job. One nal factor which should always be consideredis the effects that grouting will have on measurable parameters, such asseepage, leaks, pressure, ground or structure movements, water levels, etc.Whenever it is possible to relate the effectiveness of the grouting operation


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to such parameters, provisions should be made to record the necessary data.Where no obvious correlations are possible, it is most important that preciserecords be kept of volumes and pressures of grout for each stage of every

treated grout hole.

21.4 INSPECTION OF GROUTING

The job of an inspector is to record eld operations in sufcient detail sothat a judgment can be made as to whether the project specs are beingfollowed or violated. Normally, this will require the keeping of daily writtenrecords, often on work sheets specically tailored to the project. Theresponsibility of the inspector may overlap that of the supervisor to theextent that he/she may be required to make decisions as to whetherprocedures and equipment meet the specications. The extent of theresponsibility of an inspector should be detailed to the satisfactoryagreement of both the owner and the contractor prior to the start of eldwork. A checklist of areas for inspector activity follows.

What to Look for on the Job

MaterialsIs the grout being used that which has been specied?

Commercial productsProprietary products

Are the catalysts those specied by the manufacturer? Are they proper forthe grout properties desired?StrengthPermanence

Are site storage conditions adequate?HazardsAgingMoisture

Are the proper safety precautions used in handling the materials?Protective clothingContainer disposal

EquipmentIs the grout plant capable of controlling ow, pressure, and gel time?

SystemsbatchDual pumpProportioning

Are there readout devices for


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Depth treatedStarting pressureFinal pressure

Grout volume placedGel timeTime of treatment

Performance checksChanges in water ow

VisualWeirs

Change in permeabilityPressure recordsPumping tests

Change in strengthPenetration testPrevious data needed

21.5 REASONS FOR UNSUCCESSFUL JOBS

Completed chemical grouting projects fall into three categories: (1) thosethat were successful, as evidenced by some obvious change such as theshutoff of seepage; (2) those that were unsuccessful, as evidenced by the lackof some anticipated change such as the diversion of water; and (3) those that

cannot be judged, because (a) there might not have been a failure anyway,(b) there were no methods or attempts made to measure the results of grouting, (c) grouting was used to increase a safety factor or decrease a risk,(d) opinions differed as to the need for grouting in the rst place, etc.

It is probable that many jobs which are considered failures are placedin that category because adequate denitions of success or failure were notpredetermined. However, there is much that can be learned from those jobswhich were obvious failures. Analysis of such work indicates that failure cangenerally be explained by the obvious statement of not enough grout in theright place. As trite as the phrase seems, it is still worth looking into thereasons for not enough grout and not in the right place.

To begin with, jobs may fail or be unevaluable because of lack of engineering data. Work is often begun without reasonable knowledge of formation geology, voids, and permeability. Coupled with this shortcomingis often the failure to set up pressure and volume goals that permit theevaluation of the unknown factors. (Grouting each hole to a take refusal ishardly ever an efcient way to use chemical grouts.) Of course, smallprojects often cannot justify an engineering preevaluation. In such cases, it is


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vital that mutually satisfactory evaluation procedures (preferably somewhich relate to ongoing processes rather than end-of-job parameters) beestablished between the owner and the contractor.

Jobs may be unsuccessful because of the failure to consider the totalproblem. For example, shutting off several leaks in a porous formation maybe readily accomplished but will only result in chasing those leaks elsewhere.Similarly, shutting off large quantities of seepage may raise the water tableand create new problems.

Jobs may also be considered unsuccessful because of poor record-keeping. If obvious visible changes do not occur, work must be judged onthe basis of pumping volumes and pressures as holes were sequentiallygrouted. If such data were not kept, or were not precise enough, the workcannot be judged.

Even when engineering data are adequate and available, jobs may failbecause of poor judgment. The most obvious case of this kind is doing a jobfor which grouting just is not suitable, for example, trying to permeateorganic silts and clays. Less obvious cases of poor judgment includedeliberately pumping only enough grout to ll a portion of the voids. (Manysuccessful jobs have been done by the Joosten process on the basis of llingone-half to two-thirds of the formation voids. Less viscous grouts cannotoften be used successfully on the same basis.) With the relatively viscoussolutions used in the Joosten process and in the high-concentration single-shot silicates, it has been shown that some of the ner voids (in soils whichapproach the limits of those solutions penetrability) remain ungrouted. For

such cases, it may be appropriate to design pumping volumes based onlling 80 % to 90 % of the voids. When using those materials in coarseformations or the grouts whose viscosities approach water, design volumesshould be based on lling all the formation voids.

Another case of poor judgment includes wrong assumptions concern-ing the effectiveness of partial cutoffs. For example, if 75 % of a proposedcutoff wall has been grouted, that does not mean that the cutoff is 75 %effective. In fact, the long-term effectiveness may be very low, as theprevious total volume now ows through a reduced area at a higher velocityand carries away solids to enlarge its channels.

Any of the factors discussed above may result in the placing of insufcient groutoften the direct cause of job failure. Too little groutedvolume can also occur for reasons independent of engineering data, design,or judgment. One of these reasons is related to equipment. It is always amistake to do eld work with inadequate equipment. If the equipment usedto place grout pipes cannot do so accurately, chances are that there will begaps in many places where closure is necessary. If the grout pipes are justwhatever is handy, rather than specic tools for placing grout, plugged pipes


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may be misinterpreted as pressure refusal, and grout is not placed where itshould be. Using pumps of insufcient pressure capacity will also result inplacing less grout than may be planned and necessary. Using batch

equipment may preclude the use of gel times short enough to keep the groutfrom owing away from the zone to be treated or from being excessivelydiluted. Finally, the lack of accurate measuring devices for the grout volumeand pressure may render the grouting records useless and the groutingoperation haphazard.

Even with adequate engineering and equipment, stabilized volumemay be insufcient because of procedural errors. If the grout does not set upat all, obviously the job will fail. Failure of the grout to set up can be due toequipment malfunction or error in measurement which results in lack of catalysis, to problems with groundwater chemistry or pH (the classicexamples are using a grout which sets only under acid conditions in an areapreviously grouted with cement and using an unbuffered basic grout in coalmines), and to temperature changes in the ground which signicantly changethe preset gel time.

Even if the grout does set up, it serves no purpose if it does not set upin the right place. Liquid grout can be dispersed by selective ow inunsuspected open channels and by excessively long gel times which permitgravity ow above the water table, displacement by normal groundwaterow, and dilution with groundwater which still further prolongs the geltime. Grout may also be dispersed to ineffectiveness by improper use (or nouse) of isolating packers and by an incorrect sequence of grouting holes and

stages within a hole.Grout which sets up too quickly may be just as ineffective as groutwith excessively long gel times. (These discussions emphasize the need forregular gel checks at the point where catalyzed solution enters theformation.) Most of the reasons for prolonging gel times (discussed above)also apply to shortening gel times. These include equipment malfunction ormeasurement errors leading to excess catalysts, improper pumping rates,contamination in tanks and piping, and temperature and groundwaterchemistry.

Finally, a job failure (or the consideration of a job as having beenineffective) may be due to lack of knowledge of how to measure jobeffectiveness or facilities to do so.

21.6 SUMMARY

On large construction projects it is slowly becoming standard practice toinclude a section dealing with chemical grouting in the job specications.Unless the job is being let on a performance basis, the specications should


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F IGURE 21.1 Flow chart for planning a grouting job.


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be sufciently detailed to ensure that the work will be done by qualied andexperienced personnel.

Guidelines can readily be established for personnel being trained for

supervision and inspection of a grouting operation. Only experience,however, can adequately prepare grouters to recognize those occasionswhen exceptions and deviations from specied procedures are warranted.Good specications will include provisions for such job-dictated changes.

Preplanning of a grouting operation greatly increases the chances of a job well done, both mechanically and economically. Flow charts illustratingthe sequence of the various parameters which merit consideration are part of every contractors bag of tools. One such chart is shown in Figure 21.1. Of utmost importance are the rst two steps. The problem and an acceptablesolution must be dened in full detail, to the satisfaction of all partiesinvolved. This will reduce the occurrence of misunderstandings anddisagreements (and legal proceedings). Clearly written specications arepart of the process of making the project run smoothly.

21.7 REFERENCES

1. Guide specications for chemical grouts, J. Soil Mech. Found. Div., Proc. ASCE ,345352 (March 1968).

2. Preliminary glossary of terms relating to grouting. J. Geotech. Eng. Div. Proc.ASCE , 803815 (July 1980).

3. C. W. Clough, W. H. Baker, and F. Mensah-Dwumah, Development of DesignProcedures for Stabilized Soil Support Systems for Soft Ground Tunnelling,Final Report, Oct. 1978, Stanford University, Stanford, California.

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