geo grid foundation stabilization installation instructions
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March 2004 Page 1 of 7 Specification for Mechanically Stabilized
Earth Foundation Improvement System
SECTION 0XX00
SPECIFICATION FOR MECHANICALLY STABILIZED
EARTH FOUNDATION IMPROVEMENT SYSTEM
## THIS SECTION IS WRITTEN IN CSI 3-PART FORMAT AND IN CSI PAGE FORMAT.
NOTES TO THE SPECIFIER, SUCH AS THIS, ARE INDICATED WITH A ## SYMBOL
AND MUST BE DELETED FROM THE FINAL SPECIFICATION.
IT IS ASSUMED THAT THE GENERAL CONDITIONS BEING USED ARE AIA A201-87.
SECTION NUMBERS ARE FROM THE 1995 EDITION OF MASTERFORMAT.
PART 1 GENERAL
1.01 SUMMARY
A. Section Includes - Mechanically Stabilized Earth (MSE) foundation improvement system having
structural geogrids that interact with cohesionless soil to create a stiffened, high modulus raft
foundation. Work consists of:
1. Providing supplier representative for pre-construction meeting with Contractor and Engineer.
2. Furnishing structural geogrid reinforcement as specified herein and shown on the construction
drawings.
3. Storing, cutting and placing structural geogrid reinforcement as specified herein and as shown on
the construction drawings.
4. Placement and compaction of reinforced fill within the MSE foundation improvement system as
specified herein and as shown on the construction drawings.
5. Incidental earthwork as necessary to complete the MSE foundation improvement system
specified herein and as shown on the construction drawings.
**Note that this section does not include site preparation, dewatering, shoring, establishing a working
platform or earthwork other than incidental earthwork.**
## EDIT LIST BELOW TO CONFORM TO PROJECT REQUIREMENTS. VERIFY SECTION
NUMBERS AND TITLES.
B. Related Sections
1. Section 02200 - Site Preparation
2. Section 02300 - Earthwork
C. Alternates
1. Geotextile materials will not be considered as an alternate to geogrid materials for the MSE
foundation improvement system. A geotextile may be used in the cross-section to provide
separation, filtration or drainage; however, no structural contribution will be attributed to the
geotextile.
2. Alternate geogrid materials shall not be used unless submitted to the Engineer and approved in
writing by the Engineer at least 7 days before the bid letting. Polyester geogrids, whether coated
or uncoated, will not be approved for use in calcareous, alkaline, or highly acidic environments
including lime-treated or cement-treated soils, crushed limerock, or soils potentially exposed to
leachate from cement, lime, or de-icing salts. In no case shall polyester geogrids be used in soils
with a pH > 9.
3. In order to be considered, submittal packages for alternate geogrid materials must include:
a. A list of 10 comparable projects that are similar in terms of size and application, are
located in the United States, and where the results of using the specific alternate geogrid
material can be verified a minimum of 1 year after installation.
b. A sample of the alternate geogrid material and certified specification sheets.
c. Recommended installation instructions.
March 2004 Page 2 of 7 Specification for Mechanically Stabilized
Earth Foundation Improvement System
d. An explanation of engineering techniques used, and sample design drawings and
calculations prepared and sealed by a Professional Engineer licensed in the State.
e. Additional information as required by the Engineer.
4. Engineer approval of alternative systems and suppliers will be based upon the following
considerations:
a. The reinforcement for the system has been reviewed and pre-approved for use.
b. The supplier has a large enough operation, adequate financial resources, and necessary
experience to supply and support the construction on a reliable and timely basis.
c. The material supplier/manufacturer has adequate Professional Engineers’ Errors and
Omissions insurance to cover the potential liability incurred as designer of record for the
system.
## DELETE REFERENCES NOT USED IN PART 2 OR PART 3.
1.02 REFERENCES
A. Geosynthetic Research Institute (GRI)
1. GG1-87 - Standard Test Method for Geogrid Rib Tensile Strength
2. GG2-87 - Standard Test Method for Geogrid Junction Strength
3. GG5-91 - Standard Test Method for “Geogrid Pullout”
4. GG7 - Standard Test Method for Carboxyl End Group Content of Poly(Ethylene Terephthalate)
(PET) Yarns
5. GG8 - Determination of the Number Average Molecular Weight of Poly(Ethylene
Terephthalate) (PET) Yarns Based on a Relative Viscosity Value
B. American Society for Testing and Materials (ASTM)
1. D698-98 - Standard Test Method for Laboratory Compaction Characteristics of Soil Using
Standard Effort
2. D1388-96 - Standard Test Method for Stiffness of Fabrics, Option A
3. D4603-96 - Test Method for Determining Inherent Viscosity of Poly(Ethylene Terephthalate)
(PET) by Glass Capillary Viscometer
4. D4759-92 - Practice for Determining the Specification Conformance of Geosynthetics
5. D4972-95a - Test Method for pH of Soils
C. U.S. Environmental Protection Agency (U.S. EPA)
1. EPA 9090 - Compatibility Test for Wastes and Membrane Liners
D. American Association of State Highway and Transportation Officials (AASHTO)
1. Standard Specification for Highway Bridges (1997 Interim)
E. U.S. Army Corps of Engineers (U.S. COE)
1. Draft specification for Grid Aperture Stability by In-Plane Rotation
F. Tensar Earth Technologies, Inc. (TET)
1. Dimension™ Solution Software
1.03 DEFINITIONS
A. Geogrid - A biaxial polymeric grid formed by a regular network of integrally connected tensile
elements with apertures of sufficient size to allow interlocking with surrounding soil, rock, or earth and
function primarily as reinforcement.
B. Multi-Layer Geogrid - A geogrid product consisting of multiple layers of grid which are not integrally
connected throughout.
C. Minimum Average Roll Value - Value based on testing and determined in accordance with ASTM
D4759-92.
D. True Junction Tensile Strength - True tensile strength of junctions at indicated strain levels when tested
in accordance with GRI-GG2 as modified by AASHTO Standard Specification for Highway Bridges,
1997 Interim, using a single rib having the greater of 3 junctions or 8 inches and tested at a strain rate
of 10 percent per minute based on this gauge length. Values shown are minimum average roll values.
For multi-layer geogrid products, junction tensile strength testing shall be performed across junctions
March 2004 Page 3 of 7 Specification for Mechanically Stabilized
Earth Foundation Improvement System
from each layer of grid individually, and results shall not be assumed as additive from single layers to
multiple layers.
E. True Junction Tensile Modulus - The ratio of junction tensile strength to corresponding strain (e.g. 1%,
2%). The junction tensile strength is measured via GRI-GG2 as modified by AASHTO Standard
Specification for Highway Bridges, 1997 Interim, using a single rib having the greater of 3 junctions or
8 inches and tested at a strain rate of 10 percent per minute based on this gauge length. Values shown
are minimum average roll values. For multi-layer geogrid products, junction tensile modulus testing
shall be performed across junctions from each layer of grid individually, and results shall not be
assumed as additive from single layers to multiple layers.
F. Flexural Stiffness - Resistance to bending force measured via ASTM D1388-96, Option A, using
specimen dimensions of 864 millimeters in length by 1 aperture in width. Values shown are minimum
average roll values. For multi-layer geogrid products, flexural stiffness testing shall be performed
directly on the multi-layer configuration without using any connecting elements other than those used
continuously throughout the actual product, and results shall not be assumed as additive from testing
performed on a single layer of the multi-layer product.
G. Torsional Stiffness - Resistance to in-plane rotational movement measured by applying a 20 kg-cm
moment to the central junction of a 9-inch by 9-inch specimen restrained at its perimeter (U.S. Army
Corps of Engineers Draft Specification for Grid Aperture Stability by In-Plane Rotation). Values
shown are minimum average roll values. For multi-layer geogrid products, torsional stiffness testing
shall be performed on each layer of grid individually, and results shall not be assumed as additive from
single layers to multiple layers.
H. Soil Interaction Coefficient - Ci value shall be determined from long-term effective stress pullout tests
per GRI-GG5, unless through the junction creep testing of the geogrid is used to determine Ta. The Ci
value is determined as follows:
Ci = F
2 L N tan
Where: F = Pullout force (lb/ft), per GRI-GG5
L = Geogrid Embedment Length in Test (ft)
N = Effective Normal Stress (psf)
= Effective Soil Friction Angle, Degrees
I. Resistance to Long-Term Degradation - Resistance to loss of load capacity or structural integrity when
subjected to chemically aggressive environments measured via EPA 9090 immersion testing. Values
shown are typical values.
J. Reinforced Fill - Compacted structural fill placed above and below the layers of geogrid, the reinforced
fill boundaries shall be defined as the limits of the MSE foundation system as indicated on the
construction drawings.
1.04 SYSTEM DESCRIPTION
## DIMENSION SOLUTION SOFTWARE IS AVAILABLE TO THE DESIGNER FROM TENSAR
EARTH TECHNOLOGIES.
A. Design Requirements - The MSE foundation improvement system shall have been designed using the
Dimension Solution Software or other approved methodology.
B. Performance Requirements for the MSE Foundation Improvement System - Design calculations should
substantiate that the proposed MSE foundation improvement system satisfies the allowable total and
differential settlement and bearing capacity factor of safety design parameters as shown in the
construction drawings or as required by the Engineer.
1.05 SUBMITTALS
March 2004 Page 4 of 7 Specification for Mechanically Stabilized
Earth Foundation Improvement System
A. Submit geogrid product data sheet and certification from the manufacturer that the geogrid product
supplied meets the requirements of sub-part 2.02 of this Section.
B. Submit manufacturer’s installation instructions and general recommendations.
C. Working Drawings for Alternative Foundation Support Systems or Materials.
1. Complete details, including working drawings and supporting design calculations, for any
alternative approved foundation support systems or materials shall be submitted by the
Contractor to the Engineer for review at least 4 weeks before construction. The Contractor shall
submit 6 sets of detailed design calculations, construction drawings, and shop drawings for
approval. The calculations and drawings shall be prepared and sealed by a Professional Engineer
licensed in the State. The design submittal provided by the Contractor shall indicate the
procedures by which the geogrid soil reinforcement will be installed. Working drawings and
calculations shall include the following:
a. Existing ground elevations that have been verified by the Contractor for each location
involving construction of a foundation system.
b. Complete design calculations substantiating that the proposed design satisfies the design
parameters shown in the construction drawings or as required by the Engineer.
c. Complete details of all elements required for the proper construction of the system,
including complete material specifications.
d. Earthwork requirements including specifications for material and compaction of backfill.
e. Other information requirements shown in the construction drawings or called out by the
Engineer.
2. The Contractor shall not start work on any alternative foundation improvement system or
material until such drawings have been approved by the Engineer. Approval of the working
drawings shall not relieve the Contractor of any of his/her responsibility under the contract for
the successful completion of the work.
1.06 QUALITY ASSURANCE
A. Designer - The design of the MSE foundation improvement system shall be performed by a
Professional Engineer who is registered in the State where the project is located and who is familiar
with geotechnical engineering.
B. Pre-Construction Conference - Before construction of the MSE foundation improvement system, hold a
meeting at the site with the geogrid supplier, Contractor, and the Designer to review the construction
procedure. Notify the Owner, the Engineer, and/or Architect at least 3 days in advance of the time of
the meeting. The representative of the geogrid supplier shall be available on an “as needed” basis
during construction.
1.07 DELIVERY, STORAGE, AND HANDLING
A. Storage and Protection
1. Prevent excessive mud, wet concrete, epoxy, or other deleterious materials from coming in
contact with and affixing to the geogrid materials.
2. Store at temperatures above –20 degrees F (-29 degrees C).
3. Rolled materials may be laid flat or stood on end.
PART 2 PRODUCTS
2.01 MANUFACTURERS
## VERIFY SECTION NUMBERS AND TITLES.
A. An approved source of geogrid is The Tensar Corporation, Morrow, GA, or their designated
representative.
B. Substitutions: See Section 01600 and sub-part 1.01C of this Section.
March 2004 Page 5 of 7 Specification for Mechanically Stabilized
Earth Foundation Improvement System
2.02 MATERIALS
## THE PLANS SHOULD INDICATE WHERE TYPE 1 GEOGRID IS TO BE USED AND
WHERE TYPE 2 GEOGRID IS TO BE USED.
A. Structural Geogrid
1. The structural geogrid shall accept applied force in use by positive mechanical interlock (i.e. by
direct mechanical keying) with compacted soil. The structural geogrid shall possess complete
continuity of all properties throughout its structure and shall be suitable for internal
reinforcement of compacted soil or particulate construction fill materials to improve their load
bearing capacity in structural load bearing applications.
2. Polyolefin geosynthetic materials can be used in fill material with pH levels between 2 and 12.
Polyester geosynthetic materials, whether coated or uncoated, shall not be used in calcareous,
alkaline, or highly acidic environments, including the following: lime-treated or cement-treated
soils, crushed limerock, or soils potentially exposed to leachate from concrete, lime or de-icing
salts.
3. Structural geogrid shall otherwise have the following characteristics:
PROPERTY UNITS TYPE 1 TYPE 2
True 1% Junction Tensile
Modulus in Use
• MD
• XMD
kN/m
(lb/ft)
250 (17,000)
290 (20,000)
320 (22,000)
440 (30,000)
True 2% Junction Tensile
Modulus in Use
• MD
• XMD
kN/m
(lb/ft)
170 (11,750)
220 (15,000)
270 (18,200)
370 (25,000)
True Junction Tensile
Strength in Use @ 1% Strain
• MD
• XMD
kN/m
(lb/ft)
2.5 (170)
2.9 (200)
3.2 (220)
4.3 (300)
True Junction Tensile
Strength in Use @ 2% Strain
• MD
• XMD
kN/m
(lb/ft)
3.4 (240)
4.4 (300)
5.3 (370)
7.3 (500)
Flexural Stiffness mg-cm 250,000 750,000
Torsional Stiffness kg-cm/deg 2.8 4.7
Interaction Coefficient
(Granular Soil)
1.0 1.0
Resistance to Long-Term
Degradation
% 100 100
2.03 BACKFILL MATERIALS
A. Reinforced Backfill - The fill material in the reinforced fill zone shall be cohesionless material with a
maximum particle size of 2 inches, have less than 15 percent passing the No. 200 Sieve, and an internal
friction angle of at least 30 degrees. In addition, if gravel is used as the fill material, it shall be well
graded.
2.04 CONSTRUCTION DOCUMENTATION
March 2004 Page 6 of 7 Specification for Mechanically Stabilized
Earth Foundation Improvement System
A. The Contractor shall establish and maintain quality control for foundation construction operations to
assure compliance with contract requirements and maintain detailed records of their quality control for
all construction operations. Three copies of all records of inspections and tests, and all of the records of
corrective action taken, shall be furnished to the Engineer on a monthly basis when work under this
section is being performed.
PART 3 EXECUTION
3.01 EXAMINATION
A. The Contractor shall check the geogrid upon delivery to verify that the proper material has been
received. The geogrid shall be inspected by the Contractor to be free of flaws or damage occurring
during manufacturing, shipping, or handling.
3.02 FOUNDATION PREPARATION
A. Brush, trees, logs, topsoil, and other debris shall be removed as specified in the contract documents.
No fill shall be placed on frozen ground. After clearing, grade smooth, compact, and establish the
proper elevations as shown on the construction drawings or as directed by the Engineer.
3.03 STRUCTURAL GEOGRID INSTALLATION
A. Structural geogrid shall be laid at the proper elevation and alignment as shown on the construction
drawings.
B. For square or rectangular footings, the structural geogrid shall be oriented such that the roll direction
runs perpendicular to the roll direction of the previous layer of geogrid. For strip footings, the
structural geogrid shall be oriented such that the roll length runs parallel to the footing direction. A
minimum of 2 layers of structural geogrid are required for the MSE foundation improvement system.
C. Geogrid may be temporarily secured in place with staples, pins, sand bags or backfill as required by fill
properties, fill placement procedures or weather conditions, or as directed by the Engineer.
D. Overlap
1. Structural geogrid sections shall be overlapped as indicated on the construction drawings or as
directed by the Engineer.
2. Minimum overlap is 1 foot (300 millimeters).
3. Care shall be taken to ensure that structural geogrid sections do not separate at overlaps during
construction. To prevent separation, simple joining methods may be utilized, such as wire tires,
plastic ties, hog rings, staples or hooks. Joint spacings of 20 to 30 feet are normally adequate to
prevent grid separation at overlaps.
3.04 GRANULAR FILL PLACEMENT OVER STRUCTURAL GEOGRID
## VERIFY SECTION NUMBERS AND TITLES.
A. The fill in the reinforced zone shall be placed in lift thickness as directed in the construction drawings
or as directed by the Engineer. The fill in the reinforced zone shall be compacted to a density of at least
95 percent maximum density as determined by Standard Proctor Test (ASTM D698-98), or an
equivalent fill density measured by other methods. Otherwise, the fill in the reinforced zone shall be
placed in lifts and compacted as directed under Section 02300 and Section 02700. Granular fill
material shall be placed, spread and compacted in such a manner that minimizes the development of
wrinkles in the geogrid and/or movement of the geogrid.
B. A minimum loose fill thickness of 6 inches is required prior to operation of tracked vehicles over the
geogrid. Turning of tracked vehicles should be kept to a minimum to prevent tracks from displacing the
fill and damaging the geogrid. When integrally-formed geogrids are used, rubber-tired equipment may
pass over the geogrid reinforcement at slow speeds (less than 10 mph). When coated geogrids or
March 2004 Page 7 of 7 Specification for Mechanically Stabilized
Earth Foundation Improvement System
geogrids composed of small-diameter fibers are used, rubber-tired equipment shall not be allowed
directly on the geogrid. Sudden braking and sharp turning movements shall be avoided.
3.05 REPAIR
A. Any geogrid damaged during installation shall be replaced by the Contractor at no additional cost to the
Owner.
B. Coated geogrids shall not be used if the coating is torn, shedding, cracked, punctured, flawed or cut,
unless a repair procedure is carried out as approved by the Engineer. The repair procedure shall include
placing a suitable patch over the defective area or applying a coating solution identical to the original
coating.
3.06 PROTECTION
A. Follow the Manufacturer’s recommendations regarding protection from exposure to sunlight.
END OF SECTION
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