This document summarizes research on using fiber reinforced polymers (FRP) to improve the durability of pervious concrete. Laboratory testing found that higher dosages of longer macro-fibers significantly increased tensile strength, reduced raveling and abrasion, and dramatically improved freeze-thaw durability. Specifically, mixes with 7.5 lbs/yd of 2.25" fibers saw a 44% increase in tensile strength, 15-30% reduction in abrasion losses, and up to 3 times greater freeze-thaw durability compared to plain pervious concrete. The research demonstrates that FRP fibers can enhance the long-term performance of pervious concrete pavements.

1. FRP
Fiber Reinforced Pervious
“Pervious in Paradise”
National Pervious Concrete Pavement Association
San Diego, CA
August 5, 2014
“Pervious in Paradise”
National Pervious Concrete Pavement Association
San Diego, CA
August 5, 2014

2. Pervious concrete is
designed to allow storm
water to pass through
it, and more slowly be
distributed into a site
drainage system.
INTRODUCTION

3. INTRODUCTION
The void structure is achieved by removing the
sand/cement/water paste fraction of the mix.
What remains is cement-covered coarse
aggregates stacked together, allowing 15% to
30% voids.

4. INTRODUCTION
The very void system that allows pervious to
be permeable reduces its strength – paste is
stronger than air!
The constant challenge is a durable
balance between permeability
and strength.

5. INTRODUCTION
Owners, designers, contractors and
researchers continue to search for
methods and materials that will add back
toughness and durability to all types
of pervious pavements.

6. ASTM
Synthetic Fiber History and Background
►Founded in 1978, FORTA Corporation was the first to bring
synthetic fiber technology to the U.S. and has pioneered
manufacturing, testing and projects around the world.
►Over 30 years of research, practice and experience have
helped FORTA®
develop new applications and technology.
►FORTA®
developed a fiber-characteristic formula to help guide
fiber parameters for new applications.
FIBER: BACKGROUND

7. ASTM
Fiber Characteristic Formula: 4-C’s
►CONFIGURATION
Fiber shape and configuration affect both performance and
mixability
►CHEMISTRY
Fiber make-up determines strength and long-term durability
►CONTENTS
Dosage affects performance and user friendliness
►CORRECT LENGTH
Fiber length affects performance, mixability and friendliness.
FIBER: BACKGROUND

8. ASTM
FIBER: PERVIOUS
Fiber Development for Pervious Concrete

9. ASTM
Optimum Fiber Characteristics for Pervious
C - CONFIGURATION
blend of heavy-duty macro-filaments with small amount of
micro-fibrillated.
C - CHEMISTRY
high-strength co-polymer and recycled polypropylene
C - CONTENTS
2.5 to 7.5 lbs. / cu. yd.
C – CORRECT LENGTH
1 ½” – 2 ¼”
FIBER: PERVIOUS

10. ASTM
FORTA®
FERRO-GREEN®
► Unique blend of twisted-bundle macro fibers and
recycled polypropylene
► Specifically designed to mix, distribute and
finish well in pervious concrete
► Dosage ranges from 0.17% to 0.5% by volume
-2.5 lbs. / cu. yd., curbs and sidewalks
-5.0 lbs. / cu. yd., light-duty car park lots
-7.5 lbs. / cu. yd., high traffic paving lanes
FIBER: PERVIOUS

11. ASTM
Various research programs have been
performed for low dosages of micro fibers.
FORTA®
research focused on potential
enhancements to toughness and durability
offered by synthetic macro fibers.
FRP ResearchFRP RESEARCH

12. ASTM
Durability research program
► University of Missouri – Kansas City
► Dr. John Kevern, P.E. Assistant Professor of Civil
Engineering
► March 2013
► “Investigating the Durability of Pervious Concrete
Reinforced with FORTA®
FERRO-GREEN®
Macro Fibers”
FRP RESEARCH

13. ASTM
Goal was to determine optimum fiber length and
dosage to enhance durability issues:
► Tensile strength
► Abrasion resistance
► Freeze-thaw durability
FRP RESEARCH

14. ASTM
Test Mix Design (per cubic yard)
Cement 573 lbs.
3/8” crushed limestone 2175 lbs.
River sand 165 lbs.
Water 195 lbs.
High-range water reducer 4oz./cwt
Air entrainer 2oz./cwt
Hydration stabilizer 6oz./cwt
*Design void content 25%
Fiber Parameters
Type synthetic macro blend
Length 1-1/2”, 2-1/4”
Dosages 2.5, 5.0, 7.5 lbs. / cu. yd.
FRP RESEARCH

15. ASTM
Compressive (ASTM C39)
7 day 28 day
Control 2188psi 2423psi
Fiber Ave. 2240psi 2496psi
► As expected. No fiber change to compressive strength
once densities were equalized
FRP RESEARCH

16. ASTM
Splitting Tensile Strength (ASTM C496)
► Higher fiber dosage – higher strength
► Longer fiber length = higher strength
► 7.5 lb. / cu. yd. of 2.25” fiber = +44%
FRP RESEARCH

17. ASTM
Raveling Resistance (ASTM C1747) FRP RESEARCH
Raveling specimens
before and after testing
► 4”diameter x 4” high cylinders
► LA abrasion method
► Fiber addition reduced
abrasion losses by 5% to 15%
► No trend re: fiber dosage or
length

18. ASTM
Surface Wearing (ASTM C944)
Surface abrasion device
FRP RESEARCH
► No clear trend re: fiber
dosage or length
► All fiber mixes showed
considerable abrasion
improvement – 30% to 65%
reduction in abraded losses
► Most common cold-
weather durability issue =
snow plow abrasion
► Fiber contribution to this
durability issue is significant

19. ASTM
Freeze Thaw Resistance (ASTM C666)
Freeze-thaw apparatus
FRP RESEARCH
► Specimens tested
under worst-case
scenario – completely
saturated condition in
rapid freeze thaw cycles
► Test completed at 300
cycles or 15% mass loss

20. ASTM
Freeze Thaw Durability Factor Results
Mass Durability RDM Durability
Control 53 14
2.5lb./1.5” 38 12
5.0lb./1.5” 53 7
7.5lb./1.5” 85 21
2.5lb./2.25” 89 40
5.0lb./2.25” 91 41
7.5lb./2.25” 96 44
► Higher retained mass = higher durability
► Higher relative dynamic modulus factor = higher durability
► Long fiber mixes = 3 times the RDM durability
FRP RESEARCH

21. ASTM
Freeze Thaw Results
► The plain and 2 low-dosage, short fiber mixes failed prior to the 300 cycle
regimen, however the failure mode was completely different
Control failed at 187 cycles with complete loss of integrity
1-1/2” fiber @ 2.5lbs./cu. yd. failed at 133 cycles in single-crack mode
1-1/2” fiber @ 5.0lbs./cu. yd. failed at 188 cycles yet retained integrity
FRP RESEARCH

22. ASTM
Freeze Thaw Results
► The high-dosage 1-1/2” fiber mix and all dosages of 2-1/4” fiber reached 300 cycles with
ease. The condition of the specimens improved dramatically with increased dosage.
1-1/2” fiber @ 7.5lbs./cu.yd. at 300 cycles
2-1/4” fiber @ 2.5lbs/cu.yd. at 300 cycles
2-1/4” fiber @ 5.0 lbs./cu.yd. at 300 cycles
2-1/4” fiber @ 7.5lbs./cu.yd. at 300 cycles retained almost complete
integrity
FRP RESEARCH

23. ASTM
UMKC Research Summary
► Fibers = no reduction to compressive strength
► Fibers = considerable increase to tensile strength +44% at
7.5lbs. of 2-1/4”
► Fibers = considerable reduction of raveling and abrasion for
both fiber lengths and all dosages
► Fibers = dramatic increase to freeze-thaw durability with long
fibers @ 3x durability factor
► Fibers = tremendous over-all improvement to pervious
concrete durability
FRP RESEARCH

24. ASTM
Current Performance Levels and Fiber Recommendations
Level 1: Shrinkage crack control
1.0 lb. / cu. yd., short ½” – ¾”, monofilament
Level 2: Shrinkage crack control, stability contributions
1.5 lb. / cu. yd., ¾” -1 ½”, fibrillated-net recycled
polypropylene
Level 3: Crack control, considerable stability enhancements, improved
post-crack toughness and durability
2.5, 5.0 or 7.5 lbs. / cu. yd., 1 ½”-2 ¼”, twisted-bundle macro-
filament blended with recycled polypropylene
FIBER: SUMMARY

25. ASTM
FRP: CONCLUSIONS
► Historic perception of pervious
concrete has been question of long-
term durability
► Project use and laboratory research
have offered considerable evidence
that macro synthetic fibers can improve
durability
► Aside from changes to materials and
practice, fibers represent the best
opportunity to improve pervious
concrete pavements.

26. Thank You!
FORTA Corporation
100 Forta Drive
Grove City, PA 16127
800-245-0306
www.forta-corp.com