Underwater Concrete Technologies in Marine Construction ProjectsSam X. YaoBen C. Gerwick, Inc.Concrete Production from a Floating Batch PlantConventional Tremie PlacementConcrete Delivery on Transit MixersPlacing Concrete from a Delivery BargeTremie Placement with Suspended PipesUnderwater Concrete Construction TechnologiesConcrete Mix ProportionsWorkability and RheologyUnderwater Concrete ConstructionConcrete Production/TransportationConcrete Placement PlanningConcrete Placement ProceduresInspection and Quality ControlMass Tremie Concrete PropertiesThermal BehaviorLaitance, Bleeding, SegregationForm PressureStrength DevelopmentFinish and ProtectionPerformance Requirements for Underwater Concrete in Structural Applications• Flowability and Self-Compaction• Workability Retention within Work Window• Cohesion Against Washout, Segregation, and Laitance Formation• Low Bleeding• Low Heat of Hydration• Controlled Set Time• Compressive Strength• Adequate BondWashout Test and Slump TestSlump vs. Slump FlowMock-up Tremie Concrete TestMock-up Tremie Concrete TestPrincipal Parameters in Mix Design• Particle Packing Characteristics - Sand Content, Gradation, Size, and Shape• The water-to-fine ratio - Enough Fine to Make It Flowable and Cohesive (0.85-1.0 by volume)• Cementittious Material Content – High VolumeFly Ash plus Silica Fume• Dispersion characteristics - Proper Use of Chemical Admixtures – HRWR and Set-retarderTremie Concrete Placement Planning – An OverviewConcrete Production & Delivery: Method & RateAllowable Flow DistancePlacement Area ConfigurationAllowable Work WindowConcrete Placement SequenceTremie Pipe LayoutTremie Placement Rate& ProcedureForm PressureConcrete Flow PatternForm DesignSlope, Vent, Laitance CollectorQuality of In-Situ ConcreteStrengthUniformityBondQuality control plan:Testing, sounding, inspectionRISK FACTORS•Prodcution & Delivery Logistics•Loss of Flowability•Washout - Laitance•Segregation, Bleeding•Trapping of Water•Excessive Disturbance•ErosionConcrete ProtectionInitiation of Tremie PlacementInitiation of Placement using the Dry Pipe Method with a End Plate as the SealHydrostatic Balance PointcRwcWFDWhWH++=**'H = (Wch+WwD+FR) / WcFlow Patterns of Tremie CopncreteLayered Flow -Excessive LaitanceBulging Flow -Minimum LaitanceTremie Pipe Spacing3-5 Times Depth of Tremie PoursPlacement SequenceSimultaneous Placement Method Advanced Slope MethodRemoval of Laitance UnderwaterLower Monumental DamHydraulic Flow Pattern in Stilling BasinPomona Dam Stilling BasinHydraulic Model StudyKinzua Stilling Basin18 monthsafter repairErosion DamageErosion Damage RepairErosion Repair within a CofferdamUndrewater Repair of a DamTremie Concrete over Rock AnchorCoarse AggregatesSpecific Gravity: 2.85Absorption: 1.1%Maximum Nominal Size: 3/4-inchAppearance: Clean and round-shaped with smooth surface textureFine AggregatesSpecific Gravity: 2.72Fineness Modulus: 2.9”Absorption: 3.0%Natural River SandGradations of AggregatesGrading Curve01020304050607080901001-1/2"1"3/4"1/2"3/8"#4#8#16#30#50#100#200Sieve NumberPercentage PassingSandGravelCombined Sand and GravelVolume Ratio of Fine Aggregates to Total Aggregates: 47% Volume Ratio of Coarse Aggregates to Total Solids: 42%High Volume Fly Ash Concrete for Underwater Repair• Reducting the heat of hydration in mass concrete• Increasing concrete flowability without compromising cohesion• Facilitating concrete flowability retention and extended set timeMix ProportionsMix No. 1 Mix No. 2 Mix No. 3(52% F.A) (25% F.A) (control)Cement Type II, lb./cy 390 580 740Fly Ash, lb./cy 350 160 0Micro Silica, lb./cy 40 40 40Coarse Agg, lb./cy 1.625 1,659 1,688Fine Agg, lb./cy 1,367 1,396 1,420Water, lb./cy 301.8 302.5 303.3Rheomac UW, oz/cwt 85.8 85.8 85.8Delvo, oz/cwt 117 117 117Glenium, oz/cy 102.6 156 189Compressive Strength Development0.02000.04000.06000.08000.010000.012000.00 102030405060708090Age (days)Average Compressive Strength (psi)Mix 3Mix 1Mix 2Workability TestInitial Concrete Slump – 10” to 10-3/4”Initial Slump Flow – 21” to 26”Minimum Requirement for Achieving 1:10 Slope on Top Surface of the Concrete Pours – 10” Slump and 20” Slump FlowWorkability Retention TestSlump after 60 minutes – 10” to 10-3/4”Slump flow after 60 min. – 21” to 26”Anticipated work window for a truck of concrete - 45 minutesSet Time TestMix No. 1 Set Time > 12 hourMix No. 2 and No. 3 Set Time = 7 hourAnticipated Concrete Placement Duration: 12 hoursTremie Concrete Placement at the Dam SiteTremie Concrete Placement SequenceTremie Concrete SlumpTremie Concrete PlacementConcrete CoresConventional Dam ConstructionCofferdam FailureConventional Lock ConstructionCofferdam OvertoppingCleanup After the FloodBraddock DamTowing and PositioningFloat-In Dam .pptBraddock Dam - IllustrationGroutingFloat-In Dam .pptBraddockConcrete InfillFloat-In Dam .pptBraddock Dam – Stage 5Mile 11.2Monongahela RiverOhio RiverAllegheny RiverN3 Miles27.5 River Miles from Fabrication Site to Outfitting PierBraddock L/DMile 12.8Duquesne RIDC(Outfitting Pier)Leetsdale(Fabrication Site)Mile 14.7Mile 0.0PittsburghPittsburghMile 6.2Emsworth L/DMile 13.3Dashields L/DIn-the-Wet Foundation PreparationUnderwater FoundationsFLOWPILE DRIVINGBARGESCREEDBARGEConcurrent Operations:• Dredge/Backfill• Place Base Stone• Screed Stone• Install PiersLaunch BasinSegment 1Segment 2Fabrication SiteBraddock DamTop Slab FabricationSegment 1 in Launch BasinTransport of Dam Segment 1Towing and Setting a Float-in DamBraddock DamBraddock DamSavings:1 Year$5 MillionConstruction CompleteFlorida KeysCoral Reef in Florida KeysOne of the Ground SitesDamaged Coral ReefRepair DesignPrecast Repair ModuleRepair of Corral Reef in Florida KeysSetting a Precast ModuleFloating Batch PlantsAdding Nitrogen Cooling AgentRepair of Coral Reef in Florida KeysPumping Concrete UnderwaterPlacing Underwater ConcretePlacing Concrete in Large Holes of CorralFinishing Underwater ConcreteProject LocationCoachella Canal Engineering Data• Construction period 1938-1948 • Length 123 mi • Diversion capacity 2,500 cfs • Typical section, earth lined:• Bottom width 40-60 ft • Side slopes 2:1 • Water depth 10.3 ft • Lining, clay-blanket 12 in • Typical section, concrete lined:• Bottom width 12 ft • Side slopes 1.5 :1 • Water depth 10.8 ft• Lining thickness 3.5 inSalton Sea/Coachella