Synthetic Fibers in Precast

shootperchUrban and Civil

Nov 26, 2013 (3 years and 11 months ago)

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1

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

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

Synthetic Fibers in Precast

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


Synthetic Fibers in Precast

What’s new

graph: 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 Precast

What’s new

5

Synthetic Fibers in Precast

What’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 (A
S
)



Temperature/Shrinkage reinforcement


A
S

= 0.1%


Flexural reinforcement




A
S

< 0.4%


Structural reinforcement




A
S

> 0.4%


7

Synthetic Fibers in Precast

Engineering advances


Reinforcement measured by area of steel ratio (A
s
)


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

Synthetic Fibers in Precast


Engineering advances


Fiber use by area of steel ratio (A
s
)


Temperature/Shrinkage A
s
=0.1%: Fibers clearly accepted


Flexural reinforcement: Fibers have proven effective


Structural reinforcement A
s
>0.4%: Steel required

9

Synthetic Fibers in Precast



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

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


A
s

by wall thickness requirement


A
s

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

Synthetic Fibers in Precast


Engineering advances


Septic Tanks


IAPMO Spec PS 1
-
2003



Figure 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
Area of steel ratio
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
A
S
% = .000667 * ARS
12

Synthetic Fibers in Precast


Engineering advances

ASTM C 1399 Average Residual Strength


1.
Crack the beam with spring
-
steel plate under

2.
Remove the steel plate

3.
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

Synthetic Fibers in Precast


Engineering advances



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 R
esidual Strength (psi)

200

284

220

168

196


ASTM C 1399
-

5 pcy

Average Residual Strength (ARS):


215 psi

14

Synthetic Fibers in Precast


Engineering advances

Area of steel = ARS values for synthetic fibers


Fiber Dosage Rate by Area of Steel Ratio (A
s
)
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 - A
s
Dosage lbs/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

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

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 Precast

Rework Reduction


17



Green Strength

Improved 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 Precast

Steel reinforcement alternate

Rebar cost =
$0.35
Dec. 2004 ENR 20-city ave.
Section
0.028
0.04
0.058
0.08
0.12
0.196
Thickness
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
$31.84
2.5
$8.92
$12.74
$18.47
$25.47
3.0
$7.43
$10.61
$15.39
$21.23
$31.84
3.5
$6.37
$9.10
$13.19
$18.19
$27.29
4.0
$5.57
$7.96
$11.54
$15.92
$23.88
4.5
$4.95
$7.08
$10.26
$14.15
$21.23
$34.67
5.0
$4.46
$6.37
$9.23
$12.74
$19.10
$31.20
6.0
$3.71
$5.31
$7.69
$10.61
$15.92
$26.00
7.0
$3.18
$4.55
$6.60
$9.10
$13.65
$22.29
8.0
$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 ratio
2. Cost of rebar is taken from Dec. 2004 Engineering News Record 20-city ave. for grade 60
3. 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 A
s
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
0.196
W wire size
W1.4
W2.1
W2.9
W4
W4
Thickness
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 A
s
ACI 318 - min steel 0.1% recommended
structural
Flexural reinforcement
Temp/Shrinkage control
Check for structrual zones
Synthetic Fiber Reinforcement Zones
Synthetic Fibers in Precast

Steel reinforcement alternate

21



Dosage Determination


Per IAPMO PS 1
-
2003


Partial steel replacement above A
S

= 0.4%

Synthetic Fibers in Precast

Steel reinforcement alternate

Flexural reinforcement
Temp/Shrinkage control
Check for structrual zones
Synthetic Fiber Reinforcement Zones
Table 2
Section
0.028
0.04
0.058
0.08
0.12
0.196
Thickness
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
11.7
2.5
3.3
4.7
6.8
9.3
3.0
2.7
3.9
5.6
7.8
11.7
3.5
2.3
3.3
4.8
6.7
10.0
4.0
2.0
2.9
4.2
5.8
8.7
4.5
1.8
2.6
3.8
5.2
7.8
12.7
5.0
1.6
2.3
3.4
4.7
7.0
11.4
6.0
1.4
1.9
2.8
3.9
5.8
9.5
7.0
1.2
1.7
2.4
3.3
5.0
8.2
8.0
1.0
1.5
2.1
2.9
4.4
7.1
Typ. Dosage Rate lbs-fiber/yard for flexural steel alternate
Design A
s
Minimum dosage 3 lbs/yd suggested
Overdose suggested
structural
22

Synthetic Fibers in Precast

Steel reinforcement alternate


Illustration 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 Precast

Cycle 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 Precast

Dosage

25

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

26



$ 216
12%
45 min.
$ 245
Total cost
Savings
-
(Cost
%)
-
(Cycle time)
25
0
Fiber
38
60
Plant burden
19
23
Plant supplies
20
30
Labor
4
22
Steel
(6x6 8/8)
110
110
Mix
Fiber
Alternate
Mesh
Construction
$ 216
12%
45 min.
$ 245
Total cost
Savings
-
(Cost
%)
-
(Cycle time)
25
0
Fiber
38
60
Plant burden
19
23
Plant supplies
20
30
Labor
4
22
Steel
(6x6 8/8)
110
110
Mix
Fiber
Alternate
Mesh
Construction
Payoff for fiber use


Septic Tank Example

Synthetic Fibers in Precast

Financial 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 Precast

Summary


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



Synthetic Fibers in Precast

Summary


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. billray@precastconsulting.com

Synthetic Fibers in Precast

Summary