�

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

benjamin.colulcci1@upr.edu

Irmalí Franco

Administrative Officer

irmali.franco1@upr.edu

(787)834-6385 / (787)832-4040 x 3393 or 3403

María C. Fumero

marifumero@hotmail.com

(787)519-0029