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Porous Concrete Sidewalks POROUSPOROUS CONCRETECONCRETE SIDEWALKSSIDEWALKS HowHow toto BuildBuild SidewalksSidewalks andand notnot StormwaterStormwater PondsPonds CraigCraig TosomeenTosomeen P.E.,P.E., CityCity ofof OlympiaOlympia 20072007 BenefitsBenefits ofof PerviousPervious ConcreteConcrete ThreeThree TypesTypes ofof PerviousPervious ConcreteConcrete CategorizedCategorized byby thethe admixtureadmixture name.name. DifferenceDifference inin surfacesurface texture.texture. DifferencesDifferences inin cost.cost. CompressiveCompressive strengthstrength ofof 2,0002,000 toto 3,0003,000 psi.psi. FlexuralFlexural strengthstrength ofof 200200 toto 300300 lbs.lbs. VoidsVoids contentscontents ofof 1010 toto 20%.20%. WhatWhat isis PorousPorous Concrete?Concrete? Porous concrete is a concrete material that has enough voids within it to allow water to pass freely through it. All porous concrete has a low water-to-cement ratio. Goal is to coat aggregate in cement and compress them together. Regular Porous Concrete StoneyStoney CreekCreek PorousPorous ConcreteConcrete PercocretePercocrete PorousPorous ConcreteConcrete DifferencesDifferences inin thethe TypesTypes ofof PerviousPervious ConcreteConcrete Type of Aggregate Surface Special Finish Cost Pervious Size Texture Admixture Technique Concrete Regular Large Coarse No Roller or self Lowest 3/8 inch consolidating Stoney Medium Medium Yes Self Middle Creek ¼ inch consolidating or slip form Perco- Smallest Smooth Yes Plate Highest Crete Sand Compactor BenefitsBenefits ofof PorousPorous ConcreteConcrete Does not generate stormwater runoff like traditional pavements. Allows rainwater to enter the soil. Recharges the groundwater - this is where we get our drinking water from. Protects our streams from damaging impacts of urban stormwater runoff. Stays cooler than traditional pavement; reduce in heat island effect. Does not trigger stormwater mitigation requirements; results may vary. SurveySurvey ofof ResidentsResidents Regular Porous Concrete Sidewalk In Question Didn’t like Favor of 52%52% LikeLike thethe appearanceappearance 25%25% 49%49% LessLess SlipperySlippery 9%9% 52%52% WouldWould useuse atat homehome 15%15% (if(if $$ waswas thethe same)same) 72%72% CityCity shouldshould encourageencourage 11%11% buildersbuilders toto useuse DesignDesign ofof SidewalksSidewalks TheThe subgradesubgrade mustmust bebe uncompacted.uncompacted. StorageStorage volumevolume underunder sidewalksidewalk isis designeddesigned forfor shortshort--duration,duration, intenseintense rainrain storms.storms. PreventPrevent laterallateral movementmovement ofof infiltratedinfiltrated water;water; checkcheck damsdams areare needed.needed. TheThe surfacesurface mustmust bebe sloped,sloped, inin casecase ofof failure.failure. ProtectProtect thethe edgesedges fromfrom traffic.traffic. DesignDesign ofof MaterialsMaterials EachEach materialmaterial designdesign isis aggregateaggregate specific:specific: – Slight changes in gradation changes the result. – Can’t transfer results directly. GeneralGeneral mixmix designdesign relationships.relationships. – Fractured stronger than round. – Uniform size more voids than varied size. – More W/C stronger than lower W/C. – More W/C less voids than lower W/C. BenchBench teststests andand trialstrials worthwhile.worthwhile. ScreedScreed andand RollRoll HowHow DoDo WeWe MakeMake aa PorousPorous ConcreteConcrete Sidewalk?Sidewalk? Excavate - don’t forget the check dams. Geotextile and drain rock.. Compact,Compact, EdgeEdge andand CoverCover withwith PlasticPlastic 77 DaysDays LaterLater WorkWork isis CompleteComplete ProblemsProblems withwith PorousPorous ConcreteConcrete It is hard to batch It is difficult to place ForFor aa SuccessfulSuccessful ProjectProject YouYou need:need: –– GoodGood qualityquality controlcontrol atat thethe batchbatch plant.plant. –– ExperiencedExperienced applicatorsapplicators.. QualityQuality ControlControl WaterWater contentcontent ofof allall materials.materials. WaterWater allall readyready inin thethe truck.truck. WeightsWeights ofof allall materials.materials. EducatedEducated batchbatch plantplant operatorsoperators andand trucktruck drivers.drivers. PrePre--batchbatch meetingmeeting toto gogo overover specifications.specifications. ConstantConstant feedbackfeedback onon qualityquality ofof material.material. ExperiencedExperienced ApplicatorsApplicators PreviousPrevious porousporous concreteconcrete work.work. HireHire aa leadlead oror foremanforeman withwith experience.experience. ProvideProvide installationinstallation videosvideos andand instructions.instructions. RequireRequire satisfactorysatisfactory completioncompletion ofof testtest panelspanels beforebefore startingstarting work.work. ExpectExpect FailuresFailures EvenEven withwith goodgood qualityquality controlcontrol andand experiencedexperienced applicators,applicators, failuresfailures willwill occur.occur. OlympiaOlympia routinelyroutinely hashas failuresfailures ofof upup toto 5%5% ofof thethe porousporous concrete.concrete. MitigateMitigate thethe riskrisk ofof failure,failure, clearclear testingtesting requirements,requirements, andand makemake suresure ownerowner sharesshares thethe cost.cost. TestingTesting ofof PorousPorous ConcreteConcrete PressurePressure washwash atat 3,0003,000 psi,psi, 33 inches,inches, 77 toto 6060 daysdays afterafter installation.installation. ConstructionConstruction CostsCosts Bid item Year Total Range of Average Quantity Bids Bid Price Porous Concrete 2006 4,290 $88-$119 $106 Sidewalk (SY) 2005 2,295 $66-$102 $84 Porous Concrete 2006 1,760 $43-$122 $72 Underdrain System (CY) 2005 580 $44-$131 $72 Porous Concrete 2006 4,290 $2.25-$12 $6.70 Testing (SY) 2005 2,295 $7-$8.75 $7.80 Traditional concrete sidewalk bid price of $40 /SY for the same period PorousPorous ConcreteConcrete NeedsNeeds toto BeBe CleanedCleaned It is hard to keep it clean. TreeTree LeavesLeaves andand FruitFruit TendTend toto ClogClog PorousPorous ConcreteConcrete Cleaning Can Be Performed with Pressure Washing CleaningCleaning CanCan bebe PerformedPerformed withwith aa HardHard SurfaceSurface CleanerCleaner SweepingSweeping MachinesMachines cancan bebe UsedUsed toto CleanClean PorousPorous ConcreteConcrete CleaningCleaning CanCan bebe PerformedPerformed byby VacuumingVacuuming CityCity ofof OlympiaOlympia PorousPorous ConcreteConcrete CleaningCleaning ProgramProgram VacuumVacuum cleaningcleaning once/twiceonce/twice aa yearyear (Depending(Depending onon leafleaf litterlitter load).load). ExpectedExpected costcost $0.10$0.10 perper squaresquare yard.yard. PressurePressure WashingWashing CleaningCleaning onceonce everyevery 55 toto 1010 yearsyears (depending(depending onon effectivenesseffectiveness ofof vacuumvacuum cleaning).cleaning). ExpectedExpected costcost $1.60$1.60 perper squaresquare yard.yard. FrequentlyFrequently AskedAsked QuestionsQuestions WhatWhat aboutabout freeze/thaw?freeze/thaw? –– NoNo problemproblem thethe voidsvoids allowallow thethe iceice crystalscrystals aa placeplace toto growgrow into.into. IsIs itit durable?durable? –– YESYES –– ifif itit isis batchedbatched correctlycorrectly –– PressurePressure washingwashing doesn’tdoesn’t lielie. SummarySummary ofof PorousPorous ConcreteConcrete SidewalksSidewalks HasHas significantsignificant stormwaterstormwater andand environmentalenvironmental benefits.benefits. IsIs difficultdifficult toto installinstall correctly.correctly. RequiresRequires tradingtrading stormstorm pondpond maintenancemaintenance forfor sidewalksidewalk maintenance.maintenance. CanCan savesave moneymoney onon installationinstallation dependingdepending onon projectproject sizesize andand landland cost.cost. FutureFuture ofof PorousPorous ConcreteConcrete FuturesFutures lookslooks good.good. PorousPorous concreteconcrete isis acceptedaccepted byby citizens.citizens. MoreMore productsproducts onon thethe market.market. MoreMore peoplepeople areare gettinggetting experienceexperience withwith it.it. MoreMore placesplaces itit cancan bebe used.used. PorousPorous ConcreteConcrete PaversPavers PorousPorous ConcreteConcrete BicycleBicycle LaneLane AdditionalAdditional SourcesSources ofof InformationInformation aboutabout PorousPorous ConcreteConcrete cancan bebe foundfound onon thethe webweb atat: PercoPerco--CreteCrete PorousPorous ConcreteConcrete www.percocrete.com StoneyStoney CreekCreek PorousPorous ConcreteConcrete www.stoneycreekmaterials.com RegularRegular PorousPorous ConcreteConcrete www.washingtonconcrete.org/industry/pervious CityCity ofof OlympiaOlympia www.olympiawa.gov/cityutilities/stormwater/scienceandinnovations.
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