1 Synthetic Fibers in Precast Agenda What’s new Engineering & fiber performance Synthetic Fiber...

1

Synthetic Fibers in Precast

AgendaWhat’s newEngineering & fiber performanceSynthetic Fiber benefits

–Rework reduction•Green strength•Crack control

–Steel replacement–Reduced cycle time

Financial payoffSummary

2

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


3

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


What’s newgraph: Engineering News Record 20-City average rebar price

4

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

Synthetic Fibers in PrecastWhat’s new

5

Synthetic Fibers in PrecastWhat’s new

Microfiber– Fine, fibrillated

– Temp/Shrinkage steel alternate

Macrofiber– Coarse, monofilament, deformed

– Flexural steel alternate

6

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%

7


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

8


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

9


Engineering advances

Illustration 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.

10


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)

11


Septic Tanks – IAPMO Spec PS 1-2003Figure 2

IAPMO PS 1-2003 Design Calculations & ARS Values

0.00%

0.05%

0.10%

0.15%

0.20%

0.25%

0.30%

0.35%

0 100 200 300 400 500 600

Average Residual Strength (ARS)

As

Are

a o

f st

eel

rat

io

IAPMO Design values

Notes- Published equivalence from the IAPMO spec. The points are from the look-up table, the curve is derived. - See Section 5.4.4 Table 3

AS% = .000667 * ARS

12


ASTM C 1399 Average Residual Strength

1. Crack the beam with spring-steel plate under2. Remove the steel plate3. Measure deflection under load (w/o PL) 4. Average residual strength formula

• Section (sq.in.) • Span length

5. 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)

13


1 2 3 4 5 At 0.02” deflection 1016 1469 937 855 1001 At 0.03” deflection 1102 1566 1171 915 1084 At 0.04” deflection 1149 1625 1292 942 1126 At 0.05” deflection 1184 1651 1434 967 1153

Load (lbs.)

Average 1,113 1,578 1,209 920 1,091 Beam Width (in.) Average 4.00 4.00 4.05 4.05 4.00 Beam Depth (in.) Average 4.05 4.05 4.00 4.00 4.05 Average Residual Strength (psi) 200 284 220 168 196

ASTM C 1399 - 5 pcy

Average Residual Strength (ARS): 215 psi

14


Area of steel = ARS values for synthetic fibers

Fiber Dosage Rate by Area of Steel Ratio (As)Florida Data - Equivalence Table per IAPMO PS 2-2003

0

2

4

6

8

10

12

0.00% 0.05% 0.10% 0.15% 0.20% 0.25% 0.30% 0.35%

Area of steel ratio - As

Do

sag

e lb

s/yd

Si Concrete Systems HPP

Grace* Strux

*Forta - Ferro*Nycon XL

* Euclid Tuf-strand notes- Grace, SI from published data- Euclid, Forta, and Nycon data from Florida approvals

15



•Rework reduction–Green strength–Crack control

•Steel replacement•Reduced cycle time•Dosage


16

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

Synthetic Fibers in PrecastRework Reduction

17

Green StrengthImproved early age handling strength (Green Strength)

Allows faster cycle times Provides assurance against stripping/handling damage

Synthetic Fibers in Precast Rework Reduction

18

Cracked or spalled product Shrinkage cracks during initial cure Handling cracks when product is relatively green Stripping shear or impact damage

Synthetic Fibers in Precast Rework Reduction

19

Steel Costs – stated $/yard

Synthetic Fibers in PrecastSteel reinforcement alternate

Rebar cost = $0.35 Dec. 2004 ENR 20-city ave.

Section 0.028 0.04 0.058 0.08 0.12 0.196Thickness 6x6 10/10 6x6 8/8 6x6 6/6 6x6 4/4 4x4 4/4 #4 @ 12"ew

2.0 $11.14 $15.92 $23.08 $31.842.5 $8.92 $12.74 $18.47 $25.473.0 $7.43 $10.61 $15.39 $21.23 $31.843.5 $6.37 $9.10 $13.19 $18.19 $27.294.0 $5.57 $7.96 $11.54 $15.92 $23.884.5 $4.95 $7.08 $10.26 $14.15 $21.23 $34.675.0 $4.46 $6.37 $9.23 $12.74 $19.10 $31.206.0 $3.71 $5.31 $7.69 $10.61 $15.92 $26.007.0 $3.18 $4.55 $6.60 $9.10 $13.65 $22.298.0 $2.79 $3.98 $5.77 $7.96 $11.94 $19.50

Comments: 1. Shows the value of the reinforcing steel for each area of steel ratio2. Cost of rebar is taken from Dec. 2004 Engineering News Record 20-city ave. for grade 603. Typically the cost to tie and set rebar exceeds its material cost alone.4. Typically plant production can be increased significantly by eliminating the cage.

ACI 318 - min steel 0.1% recommended

Specified Steel stated on a Cost per Yard Basis

structural

Design As

20

Area of steel determination – Determined by producer’s engineer– Measured at a vulnerable section

Table 1

Section 0.028 0.04 0.058 0.08 0.12 0.196W wire size W1.4 W2.1 W2.9 W4 W4Thickness 6x6 10/10 6x6 8/8 6x6 6/6 6x6 4/4 4x4 4/4 #4 @ 12"ew

2.0 0.12% 0.17% 0.24% 0.33%2.5 0.09% 0.13% 0.19% 0.27%3.0 0.08% 0.11% 0.16% 0.22% 0.33%3.5 0.07% 0.10% 0.14% 0.19% 0.29%4.0 0.06% 0.08% 0.12% 0.17% 0.25%4.5 0.05% 0.07% 0.11% 0.15% 0.22% 0.36%5.0 0.05% 0.07% 0.10% 0.13% 0.20% 0.33%6.0 0.04% 0.06% 0.08% 0.11% 0.17% 0.27%7.0 0.03% 0.05% 0.07% 0.10% 0.14% 0.23%8.0 0.03% 0.04% 0.06% 0.08% 0.13% 0.20%

Area of steel ratio - Given Thickness & Reinforcement

Design As

ACI 318 - min steel 0.1% recommended

structural

Flexural reinforcementTemp/Shrinkage controlCheck for structrual zones

Synthetic Fiber Reinforcement Zones


21

Dosage Determination – Per IAPMO PS 1-2003– Partial steel replacement above AS = 0.4%


Flexural reinforcementTemp/Shrinkage controlCheck for structrual zones

Synthetic Fiber Reinforcement Zones

Table 2

Section 0.028 0.04 0.058 0.08 0.12 0.196Thickness 6x6 10/10 6x6 8/8 6x6 6/6 6x6 4/4 4x4 4/4 #4 @ 12"ew

2.0 4.1 5.8 8.4 11.72.5 3.3 4.7 6.8 9.33.0 2.7 3.9 5.6 7.8 11.73.5 2.3 3.3 4.8 6.7 10.04.0 2.0 2.9 4.2 5.8 8.74.5 1.8 2.6 3.8 5.2 7.8 12.75.0 1.6 2.3 3.4 4.7 7.0 11.46.0 1.4 1.9 2.8 3.9 5.8 9.57.0 1.2 1.7 2.4 3.3 5.0 8.28.0 1.0 1.5 2.1 2.9 4.4 7.1

Typ. Dosage Rate lbs-fiber/yard for flexural steel alternate

Design As

Minimum dosage 3 lbs/yd suggested Overdose suggested

structural

22

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

23

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

24

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?

Synthetic Fibers in PrecastDosage

25



•Rework reduction–Green strength–Crack control

•Steel replacement•Reduced cycle time•Dosage


26

$ 216

12%

45 min.

$ 245Total cost

Savings - (Cost %)

- (Cycle time)

250Fiber

3860Plant burden

1923Plant supplies

2030Labor

422Steel (6x6 8/8)

110110Mix

Fiber

Alternate

Mesh Construction

$ 216

12%

45 min.

$ 245Total cost

Savings - (Cost %)

- (Cycle time)

250Fiber

3860Plant burden

1923Plant supplies

2030Labor

422Steel (6x6 8/8)

110110Mix

Fiber

Alternate

Mesh Construction

Payoff for fiber use – Septic Tank Example

Synthetic Fibers in PrecastFinancial Payoff

27

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

Synthetic Fibers in PrecastSummary

28

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


29

Who is Bill Ray

Principal at Precast Consulting Background

– Business owner PCI certified producer

– General manager Sales exceeding $15 million

– Project manager Projects exceeding $ 10 million

– Chief fin. Officer Sales exceeding $150 million

– Education

• MBA University of Chicago

• BS Florida state

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


1 Synthetic Fibers in Precast Agenda What’s new Engineering & fiber performance Synthetic Fiber...

Documents

Transcript of 1 Synthetic Fibers in Precast Agenda What’s new Engineering & fiber performance Synthetic Fiber...