DEPARTMENT OF THE ARMYU.S. Army Corps of Engineers

CECW-EG Washington, DC 20314-1000 ETL 1110-2-334

Technical LetterNo. 1110-2-334 21 August 1992

Engineering and DesignDESIGN AND CONSTRUCTION OF GROUTED RIPRAP

Distribution Restriction Statement

Approved for public release; distribution is unlimited.

CECW-EGCECW-EH

17 Novetier 1992

Errata Sheet

No. 1

ETL 1110-2-334

DESIGN AND CONSTRUCTION OF GROUTED RIPRAP

28 Au~st 1992

This errata sheet changes subparagraphs 3e and 3f on page 1 andsubparagraphs 6g(3) and 6g(5) on page 5. Replace pages 1 and 5with the enclosed pages.

Departmentof the ArmyCECW-EG US Army Corpsof EngineersCECW-EH Washington,DC 20314-1000

EngineerTechnicalLetterNo. 1110-2-334 ~’

///

/’

d Engineeringand DesignD SIGN AND ~NSTRUCTION OF GROUTEDRIPRAP

ETL 1110-2-334

21 August 1992

,/

1. Pumse. This ETL providesguidancefor the design and constructionofgrouted riprap. Items addressedincludeapplications,limitations,designconsiderations, design requirements,construction considerations,and con-structionprocedures.

.-2. ADDliCability. This ETL appliesto all Headquarters,US Army Corps ofEngineers [USACE)elementsand USACE Commandshavingcivilworks responsibili-ties for planning, design, and operation and maintenanceof civil worksprojects.

3. References.

a. EM 1110-2-1601,

b. EM 1110-2-2000,

c* EM 1110-2-2302,

d. *PublicationNo,

..-.

HydraulicDesignof FloodControlChannels

StandardPracticefor Concrete

ConstructionWith LargeStone

FHWA-IP-89-016,U.S. Departmentof TransportationHy-draulic EngineeringCircularNo. 11: “Designof RiprapRevetments.”

* e. CRD-C 148. Refer to: USAEfor Concrete and Cement,with quarterly

* f. ASTM C 94, C 685, and D

WaterwaysExperimentStation,Handbooksupplements.

4992. Refer to: AmericanSocietyforTesting and Materials, Annual Book of ASTM Standards. Availablefrom:American Society for Testingand Materials,1916Race Street,Philadelphia,PA 19103.

4. Definition. Grouted riprap consistsof stonebed and slope protectionhaving voids filled with grout or concrete to form a veneer of cementi-tious-bonded aggregate armor. Components of a properlydesignedand con-structed grouted riprapsystemincludea stableand properlypreparedslope,a free draining sub-baseor beddinglayer,and a protectionlayer consistingof sound, durable stone bondedby a mixtureof cementitiousmaterials,water,aggregates and atiixtures. Granularfilterand sub-basematerials,geotex-tiles, sub-drains, weep-holes, cutoffs,and other specialfeaturesare alsoincludedas needed.

1

ETL 1110-2-33421 Aug 92

5. Applicationsand Limitations.

. Applications. Grouted riprap may be an economicalalternativeto(1) aconcrete paving, or (2) conventional ripraptreatmentwhere required

,. stone size cannot be economicallyprocured. Largestoneis producedin rela-tively small amountsat most commercialquarriesand is, therefore,generallymore expensive.In areaswhere transportationcostsare a significantportionof the constructioncost of the ripraptreatment,it may be lessexpensivetouse grouted riprap. Typicalapplicationsincludeprotectionof bed and bankslopes in spillwayentrancechannels,zonesof turbulenceadjacentto energydissipaters, drainage ditch linings, culvertand stormseweroutfalls,anddrainways throughconventionalriprap. Otherapplicationsfor groutedriprapinclude prevention of vandalism and improvedpedestrianaccessfor recre-ation. Grouted riprapmay also be used to repairconventionalriprapwhichhas been damaged as a consequence of being subjectedto water velocitiesexceeding design values. However,extremecautionis advisedto insurethatthe stone displacement was indeed velocity relatedand not the resultofslope or foundationfailure.

b. Limitations. “’ ““”-”‘“

(1) Grouted riprapmust be used only on properlydesignedslopes. Theadditional expense of groutingrlprapcannotbe justifiedwithoutprovidingproper slope stability. Furthermore,groutedriprapplacedon a poorlyde-signed slope can have the detrimentaleffectof maskingprogressiveslopefailureuntil it has advancedfar enoughto causefailureof the ripraptreat-ment.

(2) It must be recognizedthat groutedriprapwill crack,crackingwillbe irregular, and cracks will likely extend withinthe groutmatrix andaround the peripheryof largerstones. Crackingmay causeenhancedweather-ing, includingaggressivechemicalreactions,but shouldnot significantlydi-minish the effectiveness of the treatmentif the sub-baseis properlyde-signed and constructedto provideadequatedrainagewithoutlossof sub-basematerials through cracks. G outedrlB anr shouldnot be used in areaswherefrost heave or ice In the sub-b~secan be exDectedto causeUDliftfailure.

(3) River-side slom s of leveesshouldnot be Drotectedwith ffroute~-* At first, it may appearthat a reductionin constructioncost mightbe realized if groutedriprapcouldbe providedfor leveeprotection. How-ever, levees undergo significant settlementthat cannotbe accommodatedbythe rigid nature of groutedriprap.

(4) Applying grout to salvagea failingconventionalripraptreatmentwithout proper design to addressthe causeof the failureshouldnot be un-dertaken. This practicemost oftendoes not providea successfulrepair andresults in a waste of resources. Examplesare slopefailuresresultingfromupslope surface runoff, piping-relatedinternalerosion,down-sloperiprapfailureresultingfrom toe scour,and failuresof fremently overtoppeddrain-ways and drainageditches.

2

ETL 1110-2-33421 Aug 92

is the minimum thicknessthat shouldbe applied.

(2) Gradation. Gradation of stoneto be groutedshouldbe as coarseas possible to allow for deeperpenetrationof grout. The stone shouldhaveless than five (5) percentpassinga 2-inchsieve. The most importantconsid-erateion is that a size and gradationbe chosenthat will allow for m=im~grout penetration. It is importantfrom an economicstandpointto use sim-ple, commonlyproduced,and readilyavailablegradationswheneverpossible.

9* Stone Quality. One of the most criticalelementswhich determinessuccess or failure of groutedriprapis the qualityof stone. In general,any stone suitablefor use in conventionalriprapwill be acceptablefor ueein grouted riprap. Jt is a mistaketo Suauestthat a lowermalitv of stonemay e used if the riprap Is to be uroute~.

(1) Stone Characteri8tict3. For best results,stoneused for groutedriprap should be angularfor greatestresistanceto movementand to providethe maximum surfacearea for bondingto the grout. Less angularstonemay beacceptable for use in certainenvironmentsor where use of non-quarriedrockprovides significant economic benefits. Stonepieceswith a lengthgreaterthan three times their breadthor thicknessshouldnot be used.

(2) Non-quarried Rock. Groutedriprapmay allow the uee of non-quar-ried, appropriately sized rock, like stream-rungraveland cobbles,in placeof crushed rock. It is important, however,to insurethat the stone isclean, free of debris,and satisfiesthe gradationand stone characteristicsrequirements discussed above. In some instances,this could reduce costs byeliminatingsome processingand transportationcosts.

(3) Guidance. EM 1110-2-2302providesa comprehensiveoverviewof theeconomic selection and evaluationof conventionalriprapstone.Discussionsregarding suitable laboratorytests,visualinspections,and field tests are

* also includedin that manual. ASTM D 4992 also providesan extensivediscus-sion.

[4) Specifications. Specificationsshouldclearlylist retirementsfor suitablequality includinglaboratorytests and their requiredresultstoinsure satisfactory construction and to avoid conflictsand claims. Speci-fied values should reflectminimumacceptableresultsof previouslyevaluatedsourceswhich are availablefor use at a particularproject.

(5) Laboratory Tests. It is of prime importanceto be sure that re-quired tests approximate the actualfieldenvironmentof the project. Themost important laboratory tests used to determinedurabilityin severe andmoderate weathering regions are freezing-thawingand wetting-dryingtests.Dry unit weight, petrographiccharacteristics,and absorptionare parameterswhich should be determined for stone to be used in any riprapapplication.For litholoaies susceptible to the detrimentaleffectsof swellingclays,

* ethylenetestinghandling

gl~col testi~g (CRD-C 148) shouldmay also be appropriate for stoneprior to placement.

be considered. Abrasion losswhichwill undergosignificant

5

ETL 1110-2-33421 Aug 92

(6) ReactiveStone. Care shouldbe takento avoidstonetypes (for ag-gregate and riprap)which couldhave a deleteriousreactionwith cement. Al-kali-silica and alkali-carbonatereactionsare the most frequentof these re-actions. Petrographicanalysisshouldbe performedto determinewhetherreac-tivitytests are indicated. Additionalguidanceis in EM 1110-2-2000.

h. Grout Design. In general,designof the groutor concretemixturefor use in groutedriprapapplicationsshouldfollowaccepteddesignproce-dures included in EM 1110-2-2000.Typicalconsiderationsfor designof thegroutmixture should includestrengthand durabilityrequirements.

(1) Strength Requirements. Strength requirementsfor the grout arecommonly on the order of 2000 to 2500psi. Failureof groutedripraptreat-ments are most often attributedto undercuttingat the edgesof treatment,loss of beddingand in-situmaterialfrombeneaththe treatment,failuresre-sulting from excessivehydrostaticpressure,and loadsfrommaintenancevehi-cles. Experiencehas shownthat: (a) strengthof the groutwill not compen-sate for deficienciesin otheraspectsof the designand (b)higherstrengthgrout is usuallyunnecessaryif the treatmentis correctlydesigned.

(2) Durability Requirements. Groutedriprapmust be designedto re-sist deteriorationcausedby environmentalforcesincludingfreezing-thawing,wetting-drying,aggressivechemicalreactions,and abrasion. Guidancefor im-provingthe durabilityof concretematerialsis foundin EM 1110;2-2000.

(3) Mixture Design. Sanded grouts commonly have a ratioof threeparts of sand to one part of cement with water controllingconsistencyof thegrout. Sanded grouts are most successfulwhen used to preventvandalizationor removalof individualpiecesof riprapstoneby visitors. If conventionalconcrete mixture is to be used,the maximumsize of aggregateshouldnot ex-ceed 3/4 inch and it shouldincorporatefeaturesto enhanceplacementof theconcrete. Slumps on the orderof 5- to 7 inchesare requiredto allowproperpumping and placement. Water-reducingadmixturesare frequentlyused to aidin the workability of the mixturewhile loweringthe waterdemand. Air en-training admixtures are necessaryto improvethe freezingand thawingresis-tance as well as the workabilityof the mixture. Actualmixtureproportion-ing should be designedin accordancewith EM 1110-2-2000.If the aggregatesor riprap to be used is knownor suspectedto be reactiveto the alkalisinconcrete, low alkali cementshouldbe specified.Additionaladmixturesmaybe necessary in cases where the finalcolorof the groutedriprapmust bechangedfor aestheticreasons,

(4). Underwater Placement of GroutedRiprap. Underwaterplacementofgrouted riprap shouldbe avoided. However,if siteconditionsmake this im-possible,the grout design shouldbe similarto that for conventionalunderwa-ter concrete placement. The groutor concretemixtureshouldbe designedtowithstand underwaterplacementwithoutsignificantdegradation.Anti-waehoutadmixtures should be consideredin underwaterapplications.Guidanceon un-derwaterconcretingis includedin EM 1110-2-2000.

6

CECW-EGCECW-EH

EngineerTechnicalLetterNo. 1110-2-334

Departmentof the ArmyUS Army Corpsof EngineersWashington,DC 20314-1000

ETL 1110-2-334

21 August1992

Engineeringand DesignDESIGNAND CONSTRUCTIONOF GROUTEDRIPRAP

1. Pur~ose. This ETL providesguidancefor the designand constructionofgrouted riprap. Items addressedincludeapplications,limitations,designconsiderations,design requirements,constructionconsiderations,and con-structionprocedures.

2. Applicability. This ETL appliesto all Headquarters,US Army CorpsofEngineers(USACE)elementsand USACE Commandshavingcivilworks responsibili-ties for planning, design, and operation and maintenanceof civilworksprojects.

3. References.

a. EM 1110-2-1601,HydraulicDesignof FloodControlChannels

b. EM 1110-2-2000,StandardPracticefor Concrete

c. EM 1110-2-2302,ConstructionWith LargeStone

d. PublicationNo, FHWA-IP-89-016,U.S. Departmentof TransportationHy-draulicEngineeringCircularNo. 11: “Designof RiprapRevetments.”

e. USAE WaterwaysExperimentStation,Handbookfor Concreteand Cement,with quarterlysupplements.

f. ASTM C 94, C 685,and D 499. Referto: AmericanSocietyfor Testingand Materials,AnnualBook of ASTM Standards. Availablefrom: AmericanSoci-ety for Testingand Materials,1916Race Street,Philadelphia,PA 19103.

4. Definition. Grouted riprap consistsof stonebed and slopeprotectionhaving voids filled with grout or concrete to form a veneerof cementi-tious-bonded aggregate armor. Components of a properlydesignedand con-structed grouted riprapsystemincludea stableand properlypreparedslope,a free drainingsub-baseor beddinglayer,and a protectionlayerconsistingof sound,durablestonebondedby a mixtureof cementitiousmaterials,water,aggregates and admixtures. Granularfilterand sub-basematerials,geotex-tiles, sub-drains, weep-holes, cutoffs,and otherspecialfeaturesare alsoincludedas needed.

ETL 1110-2-33421 Aug 92

5. Applicationsand Limitations,

. Applications. Grouted riprap may be an economicalalternativeto(1) aconcrete paving, or (2) conventionalripraptreatmentwhere requiredstone size cannotbe economicallyprocured. Largestoneis producedin rela-tively smallamountsat most commercialquarriesand is, therefore,generallymore expensive.In areaswhere transportationcostsare a significantportionof the constructioncost of the ripraptreatment,it may be lessexpensivetouse grouted riprap. Typicalapplicationsincludeprotectionof bed and bankslopes in spillwayentrancechannels,zonesof turbulenceadjacentto energydissipaters, drainage ditch linings, culvertand stormseweroutfalls,anddrainways throughconventionalriprap. Otherapplicationsfor groutedriprapinclude prevention of vandalism and improvedpedestrianaccessfor recre-ation. Grouted riprapmay alsobe used to repairconventionalriprapwhichhas been damaged as a consequence of being subjectedto watervelocitiesexceeding design values. Howeverrextremecautionis advieedto insurethatthe stone displacementwas indeed velocity relatedand not the resultofslopeor foundationfailure.

b. Limitations.

(1) Grouted riprapmust be used only on properlydesignedslopes. Theadditional expense of groutingriprapcannotbe justifiedwithoutprovidingproper slope stability. Furthermorergroutedriprapplacedon a poorlyde-signed slope can have the detrimentaleffectof maskingprogressiveslopefailureuntil it has advancedfar enoughto causefailureof the ripraptreat-ment.

(2) It must be recognizedthat groutedriprapwill crack,crackingwillbe irregular, and cracks will likely extend withinthe groutmatrixandaround the peripheryof largerstones. Crackingmay causeenhancedweather-ing, includingaggressivechemicalreactions,but shouldnot significantlydi-minish the effectivenessof the treatmentIf the sub-baseis properlyde-signed and constructedto provideadequatedrainagewithoutlossof sub-basematerials through cracks. Groutedriura~shouldnot be used in areaswherefrostheave or ice in the sub-basecan be exnectedto causeupliftfailure.

(3) River-side sloues of leveesshouldnot be protectedwith crroutedm. At first,it may appearthat a reductionin constructioncost mightbe realized if groutedriprapcouldbe providedfor leveeprotection. How-ever, levees undergo significant settlementthat cannotbe accommodatedbythe rigidnatureof groutedriprap.

(4) Applying grout to salvagea failingconventionalripraptreatmentwithout proper design to a“ddressthe causeof the failureshouldnot be un-dertaken. This practicemost oftendoes not providea successfulrepairandresults in a wasteof resources. Examplesare slopefailuresresultingfromupslope surface runoff, piping-relatedinternalerosion,down-sloperiprapfailureresultingfrom toe scour,and failuresof frequentlyovertoppeddrain-ways and drainageditches.

2

ETL 1110-2-33421 Aug 92

6. Grouted Ri~rau Desicm. Groutedripraptreatmentsrequirespecialatten-tion to the designof stableslopes,edge and toe protections,sub-base,pres-sure relief and drainage,stonesize and gradation,stonequality,and groutdesign. Each of theseitemsis discussedin the followingparagraphs.

a. Design Forces. Designof groutedriprapmust addressthe forcestowhich the treatment will be subjected. Theseforcesinclude,but are notlimited to, scouringforcesof high velocityflow,pressurefluctuationsin-herent in highlyturbulentflow,hydrostaticpressureuplift,upliftfrom icein the sub-base,impactof floatingice and debris,and all the forceswhichaffect slope stability, Groutedriprapmay be designedto improvepedestriantrafficbut shouldnot be subiectedto vehicularloads.

b. Slope Design, Stabilityof the materialsto be protectedby grout-ed riprap controls the design of slopegeometryin the samemanner as itwould for conventional riprapprotection, Successfulgroutedripraptreat-ments are most oftenobservedon slopeswhich are flatterthan 1 verticalon1.5 horizontal. Information for slopedesignis obtainedfrom subsurfaceexplorations, laboratory test results,and stabilityanalyses, In the caseof limited treatments,experiencegainedfrom previoussuccessesor failuresin similar circumstancesmay prove adequate for designefforts. Groutedriprap is generally consideredto be a rigidstructurebut does not possesssignificant strength to bridgesizeablevoidsor withstandupliftpressures;therefore, foundation supportis critical. The foundationmust have a bear-ing capacity sufficient to support either the dry weightof the groutedriprap structure alone, or the submergedweightof the groutedriprapplusthe weight of the water beneaththe maximumwatersurfaceelevation,which-ever is greater.

c. Edge and Toe Design. Edge protection,or preventionof lateralundercutting, is one of the most importantaspectsof designfor groutedriprap projects. Most groutedriprapdesignsincludea granularsub-baseandthe need to confinethis granularmaterialto preventparticlemigrationisessential if the designis to be successful.Commonly,lateraledge protec-tion consists of a “keytransition”that is sufficientlydeep to ensurethatthe sub-basematerialswill not be exposedand lostthroughcontinuedfailureand removal of unprotectedin-situmaterials. The toe of the groutedriprapis usuallyat or below the minimumwater surfaceand may be subjectto scour-ing forcesduringfloodeventswhich can significantlyincreasethe potentialfor down-slopemigrationand subsequentlossof sub-basematerials. Further-more, it may be necessaryto placeriprapstoneand groutunderwater whichcauses greater concern for toe stability. A conventionalriprapberm willprotect the toe and insure the integrity of the sub-base. However,theriprap berm must be sizedto resistdisplacementof the stoneby high veloc-ity flow and thuswill requirelargerstone, The verticalextentof groutedriprap protection should be as determinedfromEM 1110-2-1601for conven-tional riprap treatments or as predictedfrom site-specificmodel studies.Protection shouldnormallyextendfrom belowthe anticipatedlevelof channelbed scour to the design high water level. The top edge of the treatmentrequires control of surfacedrainageto preventupsloperunofffrom flowingbeneath the groutedripraptreatment. Some typicaledge and toe designsarediscussedin EM 1110-2-1601.

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ETL 1110-2-33421 Aug 92

d. Sub-BaseDesign.

(l). General. Sub-basematerialsare requiredfor all groutedriprapto reduce the amountof groutpenetrationand to protectgeotextileswherenecessary. Designedgradationsfor sub-basematerialsmay also addressgranu-lar filterrequirementsand particlemigrationof eitherconstructionmateri-als or in-situsoils. Sub-basematerialswould thusprovidean area drainagecomponent to preventbuildupof excessivehydrostaticpressures. Typicallyaminimum of 6 inches of granular material is necessaryunder the groutedriprapto provideadequatedrainageinterceptionand control.

(2). Filter Design. The filtercan consistof well-gradedgranularmaterial or a uniformly-gradedgranularmaterialwith an underlyinggeotex-tile. The filtershouldbe designedto providea high degreeof permeabilitywhile preventing in-situ soils or sedimentdepositionfrompenetratingthefilter, causingcloggingand failure. Care must also be takento insurethatgrout does not penetratethroughthe overlyingriprapstoneto such an extentas to clog the filter.

e. Pressure Reliefand Drainage. Pressurereliefholes shouldbe pro-vided in groutedriprapto preventbuildupof hydrostaticpressurebehindorbeneath the treatment. Reliefholesshouldextendthroughthe groutand intothe underlying sub-base or granular filter, or intoa designedpocketofdrainmaterial, Caremust be takento insurethat groutdoes not clog the re-lief hole or drainpocket. Typically,3-inchdiameterpipes spacedno morethan ten feet each way shouldbe providedfor drainage. The finalspacingshould be based on drainagecharacteristicsof soilsbeingprotectedand onthe designed granularfilterlayer. The buriedend of the pipe must be pro-tectedwith a filteringsystemto preventin-situsoilsor granularfilterma-terials from migrating into the pipe. Fillingthe drainswith pea gravelwill protect against siltingand vandalism. Flapvalvesare used when fre-quent overtopping is expected. If the pipe is leftopen,drainsshouldbecleanedon a regularbasis.

f. Stone Size and Gradation,

(1) Top Size. It is generallyacceptedthat the top size of the grout-ed riprapstonemay be smallerthan that requiredfor conventionalriprap. Aspecific factor by whichthe top sizeof conventionalriprapmay be reduced,if grouted,has not been determined.One commondesignprocedureis to evalu-ate the stone size requirementsfor conventionalriprapand determineavail-ability and cost. If the requiredsizeof stoneis not readilyavailableoris cost prohibitive,the maximumsizeof economicallyavailablestonemay beused if grout is applied. Althoughthis is an unscientificprocessto deter-mine top stone size,experienceindicatesthat it will providea successfultreatment if the foundationis appropriatelyprepared,a propersub-baseisprovided and protected,adequatesub-basedrainageis provided,and good con-struction practices are followed. Experiencehas shownthat a 12-inchlayer

4

ETL 1110-2-33421 Aug 92

is the minimumthicknessthat shouldbe applied.

(2) Gradation. Gradation of stoneto be groutedshouldbe as coarseas possible to allow for deeperpenetrationof grout. The stoneshouldhaveless than five (5) percentpassinga 2-inchsieve. The most importantconsid-eration is that a size and gradationbe chosenthatwill allowfor maximumgrout penetration, It is importantfrom an economicstandpointto use sim-ple, commonlyproduced,and readilyavailablegradationswheneverpossible.

9. Stone guality. One of the most criticalelementswhichdeterminessuccess or failure of groutedriprapis the qualityof stone. In general,any stone suitablefor use in conventionalriprapwill be acceptablefor usein grouted riprap, It is a ❑istaketo suuuestthat a loweruualityof stonemay be used if the ripra~is to be arouted.

(1) Stone Characteristics. For best results,stoneused for groutedriprap should be angularfor greatestresistanceto movementand to providethe maximumsurfacearea for bondingto the grout. Less angularstonemay beacceptable for use in certainenvironmentsor whereuse of non-quarriedrockprovides significant economic benefits. Stonepieceswith a lengthgreaterthan threetimes theirbreadthor thicknessshouldnot be used.

(2) Non-quarried Rock. Groutedriprapmay allowthe use of non-quar-ried, appropriatelysizedrock,like stream-rungraveland cobbles,in placeof crushed rock. It is important, however,to insurethat the stone isclean, free of debris,and satisfiesthe gradationand stonecharacteristicsrequirements discussed above. In some instances,this couldreducecostsbyeliminatingsome processingand transportationcosts.

(3) Guidance. EM 1110-2-2302providesa comprehensiveoverviewof theeconomic selection and evaluationof conventionalriprapstone.Discussionsregarding suitable laboratorytests,visualinspections,and fieldtestsarealso included in that manual. ASTM D 499 also providesan extensivediscus-sion.

(4) Specifications. Specificationsshouldclearlylist requirementsfor suitablequalityincludinglaboratorytestsand theirrequiredresultstoinsure satisfactory constructionand to avoidconflictsand claims. Speci-fied valuesshouldreflectminimumacceptableresultsof previouslyevaluatedsourceswhich are availablefor use at a particularproject.

(5) Laboratory Tests. It is of prime importanceto be sure that re-quired tests approximate the actualfieldenvironmentof the project. Themost important laboratory tests used to determinedurabilityin severeandmoderate weathering regions.are freezing-thawingand wetting-dryingtests.Dry unit weight,petrographiccharacteristics,and absorptionare parameterswhich should be determined for stoneto be used in any riprapapplication.For lithologies susceptible to the detrimentaleffectsof swellingclays,ethylene glycoltestingshouldbe considered.Abrasionlosstestingmay alsobe appropriate for stone which will undergosignificanthandlingprior toplacement.

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ETL 1110-2-33421 Aug 92

(6) ReactiveStone, Care shouldbe takento avoidstonetypes (forag-gregate and riprap)whichcouldhave a deleteriousreactionwith cement. Al-kali-silica and alkali-carbonatereactioneare the most frequentof these re-actions. Petrographicanalysisshouldbe performedto determinewhetherreac-tivitytestsare indicated. Additionalguidanceis in EM 1110-2-2000.

h. Grout Design. In general,designof the groutor concretemixturefor use in groutedriprapapplicationsshouldfollowaccepteddesignproce-dures included in EM 1110-2-2000.Typicalconsiderationsfor designof thegroutmixtureshouldincludestrengthand durabilityrequirements.

(1) Strength Requirements. Strength requirementsfor the grout arecormnonlyon the orderof 2000to 2500psi. Failureof groutedripraptreat-ments are most often attributedto undercuttingat the edgesof treatment,loss of beddingand in-situmaterialfrombeneaththe treatment,failuresre-sulting from excessivehydrostaticpressure,and loadsfrommaintenancevehi-cles. Experiencehas shownthat: (a) strengthof the groutwill not compen-sate for deficienciesin otheraspectsof the designand (b)higherstrengthgrout is usuallyunnecessaryif the treatmentis correctlydesigned.

(2) Durability Requirements. Groutedriprapmust be designedto re-sist deteriorationcausedby environmentalforcesincludingfreezing-thawing,wetting-drying,aggressivechemicalreactions,and abrasion. Guidancefor im-provingthe durabilityof concretematerialsis foundin EM 1110-2-2000.

(3) Mixture Design. Sanded grouts commonly havea ratioof threeparts of sand to one part of cementwith watercontrollingconsistencyof thegrout. Sandedgroutsare most successfulwhen used to preventvandalizationor removalof individualpiecesof riprapstoneby visitors. If conventionalconcrete mixture is to be used,the maximumsizeof aggregateshouldnot ex-ceed 3/4 inch and it shouldincorporatefeaturesto enhanceplacementof theconcrete, Slumpson the orderof 5- to 7 inchesare requiredto allowproperpumping and placement. Water-reducingadmixturesare frequentlyused to aidin the workability of the mixturewhileloweringthe waterdemand. Air en-training admixtures are necessaryto improvethe freezingand thawingresis-tance as well as the workabilityof the mixture. Actualmixtureproportion-ing should be designedin accordancewith EM 1110-2-2000.If the aggregatesor riprap to be used is knownor suspectedto be reactiveto the alkalisinconcrete, low alkali cementshouldbe specified.Additionaladmixturesmaybe necessary in cases where the finalcolorof the groutedriprapmust bechangedfor aestheticreasons.

(4). Undenvater Placement of GroutedRiprap. Underwaterplacementofgrouted riprap shouldbe avoided. However,if siteconditionsmake this im-possible,the grout designshouldbe similarto that for conventionalunderwa-ter concrete placement. The groutor concretemixtureshouldbe designedtowithstand underwaterplacementwithoutsignificantdegradation.Anti-washoutadmixtures should be consideredin underwaterapplications.Guidanceon un-derwaterconcretingis includedin EM 1110-2-2000.

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ETL 1110-2-33421 Aug 92

7* Constmction Considerations, Site-specificconditionsat each projectmust be consideredto determineproperproceduresfor completionof all phas-es of grouted riprap construction.These conditionsmay includeaccesstothe site, types of materialsand vegetationthatmust be excavatedand re-moved, in-situbed and bankmaterials,area to be treated,and volumeof mate-rial to be placed. Thesefactorsare most importantwhen determiningthetypes and numbers of equipmentrequired,schedulingof work, and phasingofconstruction.

8. Constmction Procedures. In general, constructionprocedures willinclude: (a) bank clearing and grading,(b) foundationpreparation,(c)placement of filtercoverand sub-basematerials,(d) placementof stone,(e)grouting of interstices, (f) placementof edge and toe protection,and (g)revegetationof disturbedareas.

a. Foundation Treatment. The site shouldbe preparedby clearingalltrees and debris, and gradingthe bank to a stablegeometry, Care muet betaken to insurethat naturaldrainagelayersor horizonswithinthe bank,arenot blockedby constructionactivities. Placementof the sub-baselayerwillgenerally fill local depressions. Only freedrainingmaterialsshouldbeused to fill a depressiontoo largeto fillwith sub-basematerial. Undernocircumstances shoulda depressionbe backfilledwith compactedimperviousma-terial.

b. Sub-base Placement. The sub-baseshouldbe spreaduniformlyandplaced by methods which will minimize segregation. Compaction of thesub-base layermay not be required;however,the surfaceshouldbe reasonablysmooth. When justifiedby quantitiesto be used,gradationtestson in-placematerial should be required. The gradedsurfaceshouldnot deviatefrom thespecified slope by more than three (3) inchesunlessclosertolerancesarespecified.

c* StonePlacement. Riprapstoneshouldbe placedto full layerthick-ness in one operationstartingfrom the bottomof the slopeand progressingto the top. Stonefor riprapshouldbe placedin such a manneras to mini-mize segregation and avoid displacing the underlyingsub-basematerialorcause damageto the geotextile. The finishedlayershouldbe free from pock-ets of small stones, clusters of largerstones,and excessivevoids. Theriprap should be a well keyedand stablemass with adjacentstoneein closecontact but without alignment of longer faces so that open jointsareformed. Stonesshouldhave theirgreatestdimensionacrossthe slopeand thesmaller spaces between stonee would be left open to readilyreceivethegrout. Riprapstoneshouldbe free of finesto easilyfacilitategroutpene-tration. The ripraplayerthicknessshouldneverbe less than 12 inchesandshould not deviate from the specifiedvalueby more than three incheswhengreater thicknessesare required. Fieldtests for gradation,elongation,anddeleterious substances should be performedon randomloadsand the in-placematerial.

(1) Equipment and PlacementMethods. Distributionof varioussizesofstonee should be obtainedby (a) selectiveloadingat an approvedsourceofthe material, (b) controlleddumpingof successiveloadsduringfinalplac-ing, or (c) othermethodswhichwill producepropergradation. Placementof

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ETL 1110-2-33421 Aug 92

stoneshouldbegin at the bottomand proceedup the slopein a continuousman-ner. Rearrangingof individualstoneby mechanicalequipmentor by hand maybe required to obtaina reasonablywell-gradeddistributionof stonesizes.The following actions should not be permitted: placingriprapby dumpinginto chutes or by similar methods likelyto causesegregationor disturbsub-base material;dumpingat the top of the slopeand rollingthe stone intoplace; moving stoneby driftingor manipulationby meansof draglinebucket,dozer, or other bladeequipment;and operationof crawler-typeequipmentoneitherstockpiledor in-placeriprap.

(2) Underwater Placement. Sub-basematerialsand riprapstoneplacedunderwater shouldmeet gradationrequirementsin the containerused for plac-ing, and should be placedin a systematicmannerassurecontinuousand uni-form layers of well-gradedstoneof requiredthickness. Stoneto be placedunderwatershouldnot be cast acrossthe surfaceof the water.

(3) Preparation of Stone. The stoneshouldbe washedfree of mud anddust to assure bonding between the groutand the stone. The stoneshouldalso be wetted and free surface waterallowedto dissipatejustprior togrouting. These requirementsare of the utmostconcernif non-quarriedstoneis to be used for the ripraplayer.

d. Grout Placement.

(1) Production of Grout, Batchingand mixingequipmentshouldprovidesufficient capacityto preventcold jointsand conformto the requirementsofASTM C 94 or C 605. Materialsshouldbe stockpiledand batchedby methodsthat will preventsegregationor contaminationof aggregatesand insureaccu-rate proportioningof the ingredientsof the mixture. Groutshouldbe mixedin a mannerto producea mixturehavinga consistencywhichwill permitgravi-ty flow into the intersticesof the dumpedriprapwith limitedadditionalef-fort to effect distribution.Groutshouldgenerallybe used within30 min-utes aftermixing. Retemperingof groutshouldnot be permitted.

(2) Placing Grout, Riprapshouldnot be groutedwithoutspecialpro-tection when the ambienttemperatureis below35 degreesFahrenheitor above85 degrees Fahrenheit,or when the groutis likelyto be subjectedto freez-ing temperature before final set has occurred. Groutplacedon invertsorother nearly levelareasmay be placedin one course. Groutplacedon slopesshould be placedin successivetiersapproximatelyten feet in width,start-ing at the toe of the slopeand progressingto the top. Groutshouldbe de-posited as close as possibleto the finalpositionby a positivedisplacementpump or by a methodthatwill preventsegregationof aggregatesor loss ofmortar. Grout should be distributedover the riprappedsurfaceby use ofbrooms or spadesand workedintothe spacebetweenstonesfromtop to bottomwith suitable spades, trowels, bars,or vibratingequipment. Some barringmay be required to loosentightpocketsof riprapto aid in the penetrationof grout. Adequateprecautionsshouldbe takento preventgroutfrom pene-trating sub-basematerials. Groutshouldbe removedfrom the top surfacesofthe upper stones and from pockets and depressionsin the surfaceof theriprapby use of a stiffstablebroom,

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ETL 1110-2-33421 Aug 92

(3) Placing Underwater. When water levelspreventplacementof groutin the dry, a proper method shouldbe used to providethe leastpossibleamount of disturbanceto the groutduringplacementto minimizeweakeningofthe groutmixture. Thismethodmay includeplacementby meansof a tremie, abottom dump bucket, or by positivedisplacementpumpingthrougha suitablepipe or hose. Broom finishingshouldnot be requiredfor belowwater grout-ing.

(4) Curing end Protection.Beginningimmediatelyafterplacementandcontinuingfor at leastseven (7)days,all groutshouldbe curedand protect-ed from prematuredrying,extremesin temperature,rapidtemperaturechange,freezing, mechanical damage,flowingwater,and exposureto rain. Preserva-tion of moisturefor groutsurfacescan be accomplishedby sprinkling,pend-ing, absorptive mats or sand kept continuouslywet, impervioussheetmateri-al, or a membrane-formingcuringcompound. No workmanor loadsshouldbe per-mitted on the groutedsurfaceuntilproperstrengthhas been developed. Dur-ing cold weatherplacements,suitablecoveringsand protectionshouldbe ap-plied in accordancewith EM 1110-2-2000.

FOR THE DIRECTOR:

@&.PAULD. BARBER,P,E.Chief,EngineeringDivisionDirectorateof CivilWorks