Synthetic Fibers in Precast
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Synthetic Fibers in Precast. Agenda What’s new Engineering & fiber performance Synthetic Fiber benefits Rework reduction Green strength Crack control Steel replacement Reduced cycle time Financial payoff Summary. Synthetic Fibers in Precast. What’s New

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Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

Synthetic Fibers in Precast

Agenda

What’s new

Engineering & fiber performance

Synthetic Fiber benefits

Rework reduction

Green strength

Crack control

Steel replacement

Reduced cycle time

Financial payoff

Summary


Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

Synthetic Fibers in Precast

What’s New

  • Steel price - greater need for a fiber alternate

  • Flexural reinforcement design - much wider uses

  • Macrofiber technology - new fiber capabilities

  • SCC technology - wider range of workability

  • Synthetic fiber - proven to reduce production cost


Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

Synthetic Fibers in Precast

What’s new

graph: Engineering News Record 20-City average rebar price

Reinforcing steel price up sharply

  • Increase by 70% in 2004, additional increases forecast

  • Significant price reduction seems unlikely

    Precast producers will probably benefit!

  • Contractors are seeking alternates to steel construction

  • Architects & engineers are changing designs to precast

    Producers can get steel out of their product

  • Microfiber alternate to temperature/shrinkage steel

  • Macrofiber alternate to flexural steel


Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

Synthetic Fibers in Precast

What’s new

Why use fibers in precast?

  • Steel replacement - lower production cost: labor & materials

  • Faster cycle time- lower plant overhead per unit

  • Green strength - faster cycle time, lower cost, higher production

  • Crack control - reduce rework costs, reduced rejects

  • Reduced spalls- reduced rework costs, faster cycle time

  • Appearance- reduced plant rework, reduced field cost


Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

Synthetic Fibers in Precast

What’s new

  • Microfiber

    • Fine, fibrillated

    • Temp/Shrinkage steel alternate

  • Macrofiber

    • Coarse, monofilament, deformed

    • Flexural steel alternate


Synthetic fibers in precast engineering advances

Synthetic Fibers in Precast Engineering advances

Three levels of concrete reinforcement based on area of steel ratio (AS)

  • Temperature/Shrinkage reinforcement AS = 0.1%

  • Flexural reinforcement AS < 0.4%

  • Structural reinforcement AS > 0.4%


Synthetic fibers in precast engineering advances1

Synthetic Fibers in Precast Engineering advances

Reinforcement measured by area of steel ratio (As)

  • Example: #4 rebar cage @ 12” each way, 6” thick wall

    • #4 rebar = 0.20 sq. in.

    • Section = 6” x 12” = 72 sq inches

    • Ratio.0.20/72 x 100= 0.27%

  • Requirements for precast

    • 0.1% = ACI 318 Temperature/shrinkage minimum steel

    • 0.4% = Modulus of flexural rupture of concrete


Synthetic fibers in precast engineering advances2

Synthetic Fibers in Precast Engineering advances

Fiber use by area of steel ratio (As)

  • Temperature/Shrinkage As=0.1%: Fibers clearly accepted

  • Flexural reinforcement: Fibers have proven effective

  • Structural reinforcement As>0.4%: Steel required


Synthetic fibers in precast engineering advances illustration shows vacuum testing apparatus

Synthetic Fibers in Precast Engineering advancesIllustration shows vacuum testing apparatus

Septic Tanks – A flexural reinforcement test

  • Alabama tests - Vacuum tests per ASTM C 1227

    • (3) 1000 gal tanks- fiber reinforced – Failed at 9.5-10.5” Hg

    • Control tanks reinforced WWF - Failed at 4.2” Hg

  • California tests - Vacuum tests per ASTM C 1227

    • (3) 1000 gal tanks- fiber reinforced – sustained 10.0” Hg w/o failure

  • 10” hg is greater than 700 lbs/SF

    • Substantially exceeds typical earth loads

    • Provides confidence in design calcs.


  • Synthetic fibers in precast engineering advances3

    Synthetic Fibers in Precast Engineering advances

    Septic Tanks – IAPMO Spec PS 1-2003

    • Establishes the standard of quality for septic tanks

      • Concrete & reinforced plastic

      • Includes design requirements for fiber reinforcement

      • Accepted in many jurisdictions

    • Design Calculations are provided

      • As by wall thickness requirement

      • As converted to ASTM C-1399 flexural moment of resistance

      • (Standard Test Method for Determining Average Residual Strength in Fiber Reinforced Concrete)

      • Procedure for establishing fiber ASTM C-1399 values (ARS)


    Synthetic fibers in precast engineering advances4

    Synthetic Fibers in Precast Engineering advances

    Septic Tanks – IAPMO Spec PS 1-2003


    Synthetic fibers in precast engineering advances5

    Synthetic Fibers in Precast Engineering advances

    ASTM C 1399 Average Residual Strength

    • Crack the beam with spring-steel plate under

    • Remove the steel plate

    • Measure deflection under load (w/o PL)

    • Average residual strength formula

      • Section (sq.in.)

      • Span length

    • Test 5 beams

    • ARS is a measure of post-crack strength (the level of load sustained by fibers in a concrete beam after the beam is cracked)


    Synthetic fibers in precast engineering advances6

    Synthetic Fibers in Precast Engineering advances

    ASTM C 1399 - 5 pcy

    Average Residual Strength (ARS):215 psi


    Synthetic fibers in precast engineering advances7

    Synthetic Fibers in Precast Engineering advances

    Area of steel = ARS values for synthetic fibers


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in Precast

    Agenda

    What’s new

    Engineering & fiber performance

    Synthetic Fiber benefits

    Rework reduction

    Green strength

    Crack control

    Steel replacement

    Reduced cycle time

    Dosage

    Financial payoff

    Summary


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastRework Reduction

    Rework Reduction

    Extra cost to repair out of spec product.

    The cost of not doing it right the first time.

    Often not well recorded, can exceed 5% of total costs

    The rule of 10

    • It costs 10x as much to fix it in the yard as doing it right in the plant

    • It costs 10x as much to fix it on the job as does in the yard


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in Precast Rework Reduction

    Green Strength

    Improved early age handling strength (Green Strength)

    • Allows faster cycle times

    • Provides assurance against stripping/handling damage


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in Precast Rework Reduction

    Cracked or spalled product

    • Shrinkage cracks during initial cure

    • Handling cracks when product is relatively green

    • Stripping shear or impact damage


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastSteel reinforcement alternate

    Steel Costs – stated $/yard


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastSteel reinforcement alternate

    Area of steel determination

    • Determined by producer’s engineer

    • Measured at a vulnerable section


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastSteel reinforcement alternate

    Dosage Determination

    • Per IAPMO PS 1-2003

    • Partial steel replacement above AS = 0.4%


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastSteel reinforcement alternateIllustration shows vacuum testing utility vault, 20” Hg (1400 PSF)

    Application to Underground 6-sided Products

    • Septic tanks

    • Utility vaults

    • Catch basins

    • Weirs

    • Drop inlets

    • Grease traps

    • Burial vaults

      Underground round products

    • Manhole risers

    • Dry wells

    • RCP


    Synthetic fibers in precast cycle time reduction

    Synthetic Fibers in PrecastCycle time reduction

    Cycle time

    The time to set, cast, cure and strip 1 piece

    The basis of labor cost and plant burden.

    Use of fiber reduces cycle time

    • Green strength can mean stripping 2 hours earlier

    • Eliminate steel means no cage to reset

    • Reduced rework means rework product does not clutter plant

    • Reduced rework means less supervisory burden


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastDosage

    Exceed the minimum dose

    Alternate to Temp/Shrinkage steel

    • Temp steel .10%, come up to the full design

    • Allows for manufacturing & handling variation

      Alternate to flexural steel

    • Allows for manufacturing & handling variation

    • Reject pile – why take a chance?


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in Precast

    Agenda

    What’s new

    Engineering & fiber performance

    Synthetic Fiber benefits

    Rework reduction

    Green strength

    Crack control

    Steel replacement

    Reduced cycle time

    Dosage

    Financial payoff

    Summary


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastFinancial Payoff

    Payoff for fiber use – Septic Tank Example


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastSummary

    Fiber reduces production cost

    Rework reduction

    • Green strength

    • Crack control

      Steel replacement

    • Steel savings and fiber costs are similar

    • Reduced labor costs

      Reduced cycle time

    • Increased production

    • Lower burden


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastSummary

    There is a lot that’s new in synthetic fibers

    • Steel price – renewed need for a fiber alternate

    • New engineering - flexural reinforcement design

    • New fibers - macro fiber technology

    • New admixtures - SCC workability

      Engineering

    • IAPMO septic tank spec and vacuum testing shows the way

    • Fibers are becoming accepted in underground products

    • Pipe & manholes must overcome ASTM requirement

      Producers are using fibers and gaining confidence

    • Fiber manufacturers are responsive

    • Operational problems are being overcome

    • Financial results are encouraging


    Agenda what s new engineering fiber performance synthetic fiber benefits rework reduction green strength crack control

    Synthetic Fibers in PrecastSummary

    Who is Bill Ray

    • Principal at Precast Consulting

    • Background

      • Business ownerPCI certified producer

      • General managerSales exceeding $15 million

      • Project managerProjects exceeding $ 10 million

      • Chief fin. OfficerSales exceeding $150 million

      • Education

        • MBA University of Chicago

        • BS Florida state

        • Contact info: 770-979-3711. [email protected]


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