�
Rommel Cintrón – Geotechnical Engineering Grad Student
Carlos Pérez – Geotechnical Engineering Grad Student
�Module number: 1
�Title: History, Benefits, Limitations,
Materials & Equipment of the GRS-IBS
�Duration: 45 Minutes
�Level of audience: Professionals with
knowledge in civil engineering
ASTM American Standard for Testing Materials
CIP Cast-In-Place
CMU Concrete Masonry Unit
DOT Department Of Transportation
EDC Every Day Counts
FHWA Federal Highway Administration
GRS Geosynthetic Reinforced Soil
HDPE High Density Polyethylene
IBS Integrated Bridge System
MSE Mechanically Stabilized Earth
PET Polyethylene Terephthalate (Polyester)
PP Polypropylene
�EDC is designed to identify and deploy
innovation aimed at shortening project
delivery, enhancing the safety of our
roadways, and protecting the environment.
�These goals are worth pursuing for their
own sake, but in challenging times, it is
imperative to pursue better, faster, and
smarter ways of doing business.
�Teams from the FHWA work with the local
state and industry partners to deploy the
initiatives of EDC and to develop
performance measures to gauge their
success.
�GRS-IBS uses alternating layers of
compacted granular fill material and fabric
sheets of geotextile reinforcement to
provide support for the bridge.
�This technology provides an economical
solution to accelerated bridge construction.
�Is easy to build and maintain with common
labor, equipment, and materials.
�Has a flexible design that is easily modified
in the field for unforeseen site conditions.
�Has significant value when employed for
small single-span structures.
�MSE – a soil constructed with tensile reinforcing
members (steel or geosynthetic) to increase the
strength and load-bearing capacity.
�GRS – an engineered fill of closely spaced
alternating layers of geosynthetic reinforcement
and compacted granular fill material.
�IBS – a fast and cost-effective method of bridge
support that blends the roadway into the
superstructure using GRS technology.
�History
�Benefits
�Limitations
�Materials
�Equipment
�
�Reinforced soil has been used for thousands
of years
�Ancient reinforcing materials have included:
o Straw
o Tree branches
o Plant material
�Mechanically Stabilized Earth
o 1960’s: steel strips (Reinforced Earth)
o 1980’s: geosynthetic reinforcement
�Geosynthetic Reinforced Soil
o U.S. Forest Service: geotextiles for wrapped face
walls (i.e. burrito walls) in the 1970’s
o Colorado DOT: frictionally connected modular
blocks as the facing in the 1980’s
o FHWA refined the Colorado DOT method for
load-bearing applications
�Geosynthetic Reinforced Soil
o In 2002, Bridge of the Future
o In 2005, the first GRS-IBS was built in Ohio
o In 2010, GRS-IBS was selected as an EDC
initiative
o To date, 45 bridges with a GRS abutment in the
USA (28 of those are GRS-IBS)�
�
�Single span length (≤ 140 ft)
�Abutment height (≤ 30 ft)
�Low velocity stream crossings
�Grade separation
�Steel or concrete superstructures
�New or replacement structures
�Geosynthetic strength may be reduced due
to creep
�
Facing Elements
Granular Backfill
Geosynthetic Reinforcement
Miscellaneous
� Are not structural members
� Split Face CMU Block
o Readily available
o Inexpensive
o Compatible with the frictional connection to the reinforcement
o Material specifications• Dimensions: 7-5/8” x 7-5/8” x 15-
5/8”
• Compressive strength: ≥ 4,000 psi
• Water absorption limit: 5%
�GRS Abutment Backfill
o Is a structural component
o Well-graded or Open-graded aggregates
�Reinforced Soil Foundation Backfill
o Well-graded gravel
�Integrated Approach Backfill
o Well-graded gravel
�Well-graded
o dmax ≤ 2”
o #200 sieve ≤ 12%
o Φ ≥ 38˚
o PI ≤ 6
�Open-graded
o dmax ≥ 0.5”
o #200 sieve ≤ 5%
o Φ ≥ 38˚
o PI ≤ 6
� GRS Abutmento All projects to date have used woven polypropylene
(PP) geotextiles as reinforcement
o Other reinforcement materials can be used and include:
• Geogrids (PET, PP, HDPE)
• Woven geotextiles (PET)
� Reinforced Soil Foundation and Integrated Approacho Geotextiles must be used as reinforcement and to
encapsulate the material
� Recommendations:
o Biaxial reinforcement
o Roll parallel to face
� Ultimate Strength:
o Tf = 4800 lb/ft
� Strength at 2% Strain:
o T@ε=2%
Tf
T@ε=2%
� Concrete block wall fillo ASTM Class A concrete
o f 'c = 4,000 psi
� Rebaro #4
� Aluminum flashingo 4” x 1.5”
� Foam boardo 2” x 12”
� Bitumen coating
�
Hand Tools
Measuring Devices
Heavy Equipment
� Gravel rakes (concrete spreader) and heavy
rakes
� Shovels (flat blade and spade)
� Brooms to sweep top of blocks and wisk
brooms
� 2 to 3 lb sledgehammer and wood (2” x 4”) to
align blocks
� Heavy rubber mallet
� Spade trowel
� Razor knives or utility knives to cut
reinforcement
� Hand tamper with metal base plate
� Chainsaw to cut reinforcement roll
� Concrete saw
� 5 gallon bucket
� Block lifter
� Standard concrete mixing and finishing tools
� Survey equipment
� Laser level
� String line to align blocks
� 4 ft carpenter level
� Plumb bob to check wall batter
� Measuring tapes
� Chalk line
� Walk-behind vibratory plate tampers (200 lb and 18 in
wide)
� Track hoe excavator
� Riding smooth drum vibratory roller (compacting 1 m from
wall face)
� Pallet forks for excavator (for moving cubes of CMU block
in and out of work area)
� Trash pump and hose for dewatering foundation
excavation
� Backhoe (as needed for material staging)
�GRS-IBS technology is growing and has been
implemented successfully in USA
�This method has multiple benefits for small
bridges
�Only common materials and equipment are
needed for the construction
�Benjamin Colucci, PhD, JD, PE
�Michael Adams, PE
� Jennifer Nicks, PE
�Daniel Alzamora, PE
�Alvin Gutierrez, PE
�Transportation Technology Transfer Center
Staff
www.fhwa.dot.gov/publications/research/infrastructure/structures/11026/index.cfm
Benjamín Colucci, PhD, JD, PE
Principal Investigator
Irmalí Franco
Administrative Officer
(787)834-6385 / (787)832-4040 x 3393 or 3403
María C. Fumero
(787)519-0029