CONCRETE PANEL MSE RETAINING WALL
PART 1 GENERAL
1.1SECTION INCLUDES
A.Concrete panel mechanically stabilized earth (MSE) retaining wall using
metal or geogrid soil reinforcement.
1.2RELATED SECTIONS
A.Section 02317: Structural Excavation and Backfill
B.Section 02832: MSE Backfill
C.Section 03055: Portland Cement Concrete
D.Section 03211: Reinforcing Steel and Welded Wire
E.Section 03310: Structural Concrete
F.Section 03390: Concrete Curing
G.Section 03392: Penetrating Concrete Sealer
H.Section 09982: Anti-Graffiti Concrete Coating
1.3REFERENCES
A.AASHTO M 111: Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel
Products
B.AASHTO M 232: Zinc Coating (Hot-Dip) on Iron and Steel Hardware
C.ASTM A 572: High-Strength Low-Alloy Columbium-Vanadium Structural
Steel
D.ASTM A 641: Zinc-Coated (Galvanized) Carbon Steel Wire
E.ASTM A 709: Structural Steel for Bridges
Concrete Panel MSE Retaining Wall
F.ASTM A 1011: Steel, Sheet and Strip, Hot-Rolled, Carbon, Structural,
High-Strength Low-Alloy, High-Strength Low-Alloy with Improved Formability, and Ultra-High Strength
G.ASTM A 1064: Carbon-Steel Wire and Welded Wire Reinforcement, Plain
and Deformed, for Concrete
H.ASTM D 3960: Determining Volatile Organic Compound (VOC) Content
of Paints and Related Coatings
I.ASTM D 5262: Evaluating the Unconfined Tension Creep and Creep
Rupture Behavior of Geosynthetics
J.ASTM D 6637: Determining Tensile Properties of Geogrids by the Single
or Multi-rib Tensile Method
K.ASTM F 3125: High Strength Structural Bolts, Steel and Alloy Steel, Heat
Treated, 120 ksi and 105 ksi Minimum Tensile Strength
L.UDOT Quality Management Plan
1.4DEFINITIONS Not Used
1.5SUBMITTALS Not Used
1.6ACCEPTANCE
A.Concrete Wall Panels
1.Meet 28-day minimum compressive strength of 4000 psi.
2.Visually free of defects and will be rejected if they have:
a.Defects due to imperfect molding
b.Honeycombing
c.Open texture on front face
d.Cracks or spalls that exceed the limits specified in this
Section, Article 3.6
PART 2 PRODUCTS
2.1MATERIALS
A.Concrete.
1.Precast Panels
a.Class AA(AE). Refer to Section 03055.
Concrete Panel MSE Retaining Wall
2.Coping
a.Class AA(AE). Refer to Section 03055.
3.Leveling Pad
a.Class B. Refer to Section 03055.
B.Reinforcing Steel
1.Use coated reinforcing steel according to Section 03211.
C.Form-Liner Materials
1.Use a form-liner that produces uniform texture and patterns and
releases the sculpted concrete surface without damage.
2.Provide solid backing and form supports so that the form-liners
remain in place during concrete placement.
3.Use a form release agent that meets the following:
a.A manufacturer’s recommended liquid-release agent that will
not bond with, stain, or adversely affect precast concrete surfaces and will not impair subsequent surface or joint treatments of precast concrete.
b.A non-petroleum release agent meeting EPA requirements.
1) Limit Volatile Organic Compound (VOC) content to 250 grams/liter or less. Refer to ASTM D 3960.
c.A release agent that is not detrimental to concrete strength
or durability and that does not impart color, tint, or texture to the finished product.
D.Soil Reinforcement
1.Metal reinforcing elements
a.Strips
1) Hot rolled from steel bars according to ASTM A 572; or cold-formed according to ASTM A 572 or ASTM A 1011.
b.Welded Wire and Grid
1) Refer to ASTM A 1064.
c.Galvanize according to AASHTO M 111 or ASTM A 641 with
a coating thickness of at least 3.4 mils.
2.Geogrid reinforcing elements
a.Use geogrid consisting of a regular grid network of integrally
connected, discontinuous, select high-density polyethylene or polypropylene resin polymer tensile elements. 1) Aperture geometry sufficient to permit significant mechanical interlock with the surrounding soil or rock or both. 2) Geogrid structure to be dimensionally stable and be able to retain its geometry under manufacture, transport, and installation.
Concrete Panel MSE Retaining Wall
b.Meet creep rupture test for 75-year service life according to
ASTM D 5262.
c.Meet the ultimate tensile strength from wide-width tests
based on minimum average roll values, according to ASTM D 6637. 1) Utilize geogrid reinforcement reduction factors as appropriate for the project.
E.Loop Embeds
1.As provided by the Wall Company.
2.Galvanize according to AASHTO M 111 with a coating thickness of
at least 3.4 mils.
F.Tie Strips
1.Shop fabricated, hot rolled steel conforming to ASTM A 709, Grade
50, ASTM A 1011 Grade 50 or equivalent.
2.Galvanize according to AASHTO M 111 with a coating thickness of
at least 3.4 mils.
G.Panel Fasteners
1.Bolts and nuts to be hexagonal cap screw and galvanize coated,
meeting ASTM F 3125, Grade A 325 and AASHTO M 232.
H.Other Fasteners
1.Fasteners to wingwalls and abutment walls, if required, are
provided by the Wall Company.
I.Filter Fabric
1.Type and grade recommended by the Wall Company.
J.Filter Fabric Adhesive
1.According to Wall Company's standard.
K.Bearing Pads
1.Horizontal rubber bearing pads of the type and grade
recommended and supplied by the Wall Company.
L.Lifting Devices
1.According to Wall Company’s standard.
Concrete Panel MSE Retaining Wall
M.Two-Stage Retaining Wall Systems
1.Wire Facing
a.Shop fabricated of cold-drawn steel wire conforming to the
minimum requirements of ASTM A 1064. 1) Galvanize according to ASTM A 641 or AASHTO M 111 with a coating thickness of at least 3.4 mils.
2.Connector Rods
a.Fabricated from cold-drawn steel wire according to ASTM A
1064. 1) Galvanize according to ASTM A 641 or AASHTO M 111 with a coating thickness of at least 3.4 mils.
3.Hairpin Connectors
a.Shop fabricated of hot-rolled steel according to ASTM A 572,
Grade 50 or equivalent. 1) Galvanize according to AASHTO M 111 with a coating thickness of at least 3.4 mils.
N.MSE Backfill
1.Refer to Section 02832.
O.MSE Free Draining Backfill
1.Refer to Section 02832.
P.Facing Treatment Material
1.Refer to Section 03392
2.Refer to Section 09982
2.2PRECAST CONCRETE WALL PANELS
A.Follow the authorized retaining wall drawings.
2.3FABRICATION
A.Use a Department prequalified supplier of precast concrete products
according to the UDOT Quality Management Plan 505: Precast/ Prestressed Concrete Structures.
B.Precast Concrete Panels
1.Cast the panels to dimensional tolerances according to Precast
Concrete Institute (PCI) or National Precast Concrete Association (NPCA), and as shown.
a.Do not cast panels on site.
b.Cast in metal forms.
Concrete Panel MSE Retaining Wall
c.Achieve uniformity of appearance, color, texture, and
pattern.
d.Produce a concrete panel with smooth, solid surfaces free of
voids and air pockets.
2.Permanently mark each panel with the casting date, and the panel
identification number on the rear of each panel so it is legible during installation.
3.Provide the surface texture architectural treatment as shown.
a.The thickness of the architectural treatment is in addition to
the required design thickness.
b.Use a concrete form-liner to achieve the required concrete
texture.
c.Provide panel faces that are free of joint marks, grain, and
other obvious defects. Provide corners including false joints that are uniform, straight, and sharp.
4.Concrete Finish
a.Provide an ordinary surface finish according to Section
03310 for front face of panels.
b.Provide a uniform surface finish for the back face of panels.
1) Roughly screen the finish to eliminate open pockets of aggregate and surface distortions in excess of 1/4 inch.
5.Provide concrete cover to the reinforcing steel of at least 2 inch.
6.Set tie strip guides at back face.
7.Cast panels on a flat area or approved architectural treatment, with
the front face down.
8.Place concrete in each unit without interruption.
a.Vibrate with equipment that prevents stone pockets or
cleavage planes.
b.Use clean, unused form oil.
9.Cure according to Section 03390.
C.Soil Reinforcement Connections
1.Cast at least two soil reinforcement connection levels into all full-
size concrete panels.
a.Where only two connection levels are cast in panels, locate
the levels in two different horizontal planes separated by at least one-third the panel height.
Concrete Panel MSE Retaining Wall
PART 3 EXECUTION
3.1GENERAL
A.Haul, store, and ship wall materials in a manner that minimizes the
potential of producing defects.
1.Store panels to avoid damage to connection pieces, such that the
tie strips do not bend.
2.Store soil reinforcement products as recommended by the Wall
Company.
3.Inspect soil reinforcement and attachment devices to verify they are
true to size and free from defects that may impair their strength and durability.
4.Keep the soil reinforcement and connections free of contaminants.
B.Construct the retaining wall system according to the authorized retaining
wall drawings, and the Wall Company’s construction manual and recommendations.
1.Apply the stricter of the two requirements where the Department’s
and the Wall Company’s requirements differ.
3.2EXCAVATION AND FOUNDATION PREPARATION
A.Excavate and prepare foundation to the lines and grades shown, or as
directed by the Engineer.
1.Refer to Section 02317.
2.Make the width of excavation equal to or greater than the length of
soil reinforcement.
3.Excavate to a depth no lower than the level of top of leveling pad.
4.Compact the foundation using at least three passes of a lightweight
smooth-drum roller, or as determined by the Engineer before the wall construction.
5.Over-excavate unsuitable foundation soils and replace with MSE
backfill, or with other suitable material as directed by the Engineer.
3.3LEVELING PAD
A.Place the cast-in-place concrete leveling pad upon the compacted
foundation.
1.A gap no more than 5-inch wide may be left between the end of the
leveling pad for the lower concrete panel, and the end of the leveling pad for the adjacent higher concrete panel where the wall steps up if shown in the authorized retaining wall drawings.
Concrete Panel MSE Retaining Wall
a.Fully retain the backfill in the zone behind the gap.
b.Properly backfill the gap before the remaining backfill in front
of the wall face is placed.
2.Place leveling pad to a thickness of at least 6 inch.
a.Place after the required settlement has been achieved from
the first-stage wall construction for two-stage wall systems.
3.Provide a level surface so that the concrete panels are in complete
contact with the leveling pad.
B.Do not place concrete panels until leveling pad has been placed for at
least 12 hours.
3.4WALL CONSTRUCTION
A.Single-Stage Retaining Walls
1.Place panels successively above the preceding panels as backfill
placement proceeds.
2.Place panels initially at a slight batter towards the backfill as
recommended by the Wall Company to compensate for outward rotation of the panels from fill placement and compaction.
B.Two-Stage Retaining Walls
1.Closely follow the erection of each course of wire facing when
placing MSE backfill for the first stage of two-stage retaining walls.
a.Place the MSE backfill in two approximately equal lifts and
compact with lightweight equipment according to Section 02832.
b.Avoid damage or disturbance to the wall materials or
misalignment of the wire facing.
2.Construct the first-stage facing within 2 inch of the design vertical
and horizontal alignments (excluding bulging).
3.Prevent significant bulging of the first-stage facing between
reinforcing layers.
a.Where bulging exceeds 3 inch between reinforcing layers,
remove and reconstruct this portion of the wall.
b.Measure bulging by holding a plumb straight-edge, or a
plumb-bob string in front of the wall face. 1) The bulge measurement is the horizontal distance between the straight edge or plumb-bob string set at the location of maximum bulge and the reinforcement layer immediately above or below the bulge (whichever is greater).
4.Proceed with placement of the second-stage wall panels after
receiving notification from the Engineer that the required first-stage settlement has been achieved.
Concrete Panel MSE Retaining Wall
C.Place bearing pads as required by the Wall Company to prevent concrete-
to-concrete contact between panels.
D.Use rubber, wood, or metal shims as necessary to make final adjustments
to the wall panel to facilitate level placement of the panel.
1.Do not leave wood shims at any location.
E.Soil Reinforcement
1.Place soil reinforcement normal to the face of the wall in plan view
where possible.
2.Skew discrete reinforcement where required to splay the
reinforcement around obstructions.
a.Limit the skew angle to no more than 15 degrees, unless
authorized by the Engineer. 1) Follow the Wall Company’s requirements when a skew angle exceeding 15 degrees is authorized.
3.Provide at least 2 inch clear distance between metal soil
reinforcement and piles or other metallic obstructions.
4.Do not exceed horizontal spacing between soil reinforcement of 7 ft
at any point.
5.Use a crescent or socket-head ratchet wrench to securely hand-
tighten the nut where reinforcement elements are connected using bolts and nuts.
a.Place the nut on top of the connection.
b.Do not use pneumatic equipment.
6.Place the top level of soil reinforcement a distance below the top of
the wall as shown in the authorized retaining wall drawings.
a.Place the top level of soil reinforcement at least 3 inch below
the bottom of the barrier slab base or the bottom of the concrete gutter behind the coping.
7.Gradually deflect the top soil reinforcement elements downward to
avoid conflicts with paving and subgrade preparation.
a.Consider special conditions such as where roadway super-
elevation is anticipated.
8.Limit the vertical deflection of the reinforcement elements to not
more than 8 inch from the connection level or as otherwise shown in the authorized retaining wall drawings.
9.Provide at least 3 inch vertical separation between geosynthetic soil
reinforcement when overlapping.
F.Geogrid Soil Reinforcement Installation
1.Verify the correct orientation (roll direction) of the geogrid.
2.Place geogrid on compacted backfill.
3.Connect geogrid to the concrete panels.
Concrete Panel MSE Retaining Wall
4.Pull the geogrid taut to eliminate loose folds and remove slack in
the geogrid at the wall unit connections, pretension the geogrid, and stake or otherwise secure the back edge of the geogrid before and during backfill and compaction.
5.Follow the Wall Company's overlap requirements for uniaxial and
biaxial geogrids.
G.Limit the skew angle of the connector rods between the concrete panels
and the first stage facing in two-stage retaining walls to not more than 15 degrees horizontally and vertically, unless authorized by the Engineer.
1.Follow the Wall Company’s requirements when a skew angle
exceeding 15 degrees is authorized.
H.Construct wall facing to the following tolerances:
1.Horizontal alignment
a.Not to exceed 0.7 percent (for example, 2.5 inch in 30 ft).
2.Vertical alignment
a.Not to exceed a 0.7 percent difference between the vertical
slope of two adjacent panels (for example, a vertically plumb panel below a panel with a 0.7 percent vertical slope, 0.42 inch in 5 ft).
3.Plumbness from top of wall to bottom of wall
a.Positive (into the retained mass)
1) Not to exceed 0.7 percent (for example, 1.7 inch in 20 ft of wall height).
b.Negative (away from the retained mass)
1) Not to exceed 0.4 percent (for example, 0.96 inch in 20 ft of wall height).
4.Panel Levelness
a.Not to exceed 0.5 percent (for example, 1.2 inch in 20 ft).
5.Panel Joints
a.Install concrete wall panels so that joints are uniform.
b.Maximum allowable offset in any panel joint is 0.375 inch.
c.Joint width is 1.25 inch maximum and 0.50 inch minimum.
I.Check panel tolerance and reset before placement of the next panel if out
of tolerance.
J.Cover horizontal and vertical joints between panels with filter fabric.
1.Attach using filter fabric adhesive.
Concrete Panel MSE Retaining Wall
3.5WALL COPING
A.Refer to Section 03310 for concrete placing and finishing.
B.Refer to Section 03390 for concrete curing.
3.6CRACK AND SPALL REPAIR CRITERIA FOR CONCRETE PANELS
A.A fully penetrating crack is defined as a crack extending through the
cross-section of the precast panel from the front face to the back face of the unit.
B.Cracks at Front Face of Panel:
1.Panels with one or two partially penetrating cracks with widths less
than or equal to 12 mils are acceptable.
2.Reject panels with fully penetrating cracks, or cracks wider than 12
mils.
3.No more than two cracks per individual panel are allowed without
further evaluation.
C.Cracks at Back Face of Panel:
1.Partially penetrating cracks with widths less than or equal to 12 mils
are acceptable.
2.Partially penetrating cracks with widths between 12 mils and 30
mils are acceptable when repaired with surface sealant according to paragraph F, Crack Repair Procedures.
3.Evaluate partially penetrating cracks wider than 30 mils for
acceptance with epoxy injection according to paragraph F, Crack Repair Procedures.
4.No more than two repairable cracks per individual panel are
allowed without further evaluation.
D.Spalls at Front Face of Panel:
1.Spalls with widths less than 4 inch and depths less than 2 inch may
be repaired with a patching material acceptable to the Engineer of the same color as panel concrete. Resultant repair to be approved by the Engineer.
2.Reject panels with spalls wider than 4 inch or deeper than 2 inch.
3.Measure spall depth from the structural thickness of the panel
excluding architectural surface finish.
4.Panels with more than two spalls are subject to further evaluation
before acceptance.
Concrete Panel MSE Retaining Wall
E.Spalls at Back Face of Panel:
1.Spalls with widths less than 4 inch and depths less than 2 inch may
be repaired with a patching material acceptable to the Engineer. Resultant repair to be approved by the Engineer.
2.Reject panels with spalls wider than 4 inch or deeper than 2 inch.
3.Panels with more than four spalls are subject to further evaluation
before acceptance.
F.Crack Repair Procedures:
1.Surface Sealing: Prepare surface and apply a sealant acceptable to
the Engineer according to Manufacturer’s instructions.
2.Epoxy Injection: Prepare surface and inject cracks with
Department-approved product according to Manufacturer’s instructions.
G.Spall Repair Procedures:
1.Prepare surface and apply patching material according to
Manufacturer’s instructions, and as acceptable to the Engineer.
END OF SECTION
Concrete Panel MSE Retaining Wall
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Source: Utah Standard Specifications for Road and Bridge Construction, 2026 Edition. Pages 686–697 of 1,331.
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