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02834aws.txt
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1998-06-10
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SECTION 02834
MODULAR CONCRETE RETAINING WALLS
NOTE ** This section is based on products nationally
manufactured under license from Anchor Wall
Systems, Inc., which is located at the following
address:
NOTE ** 6101 Baker Road, Suite 201
NOTE ** Minnetonka, MN 55345
NOTE ** Tel: (800) 473-4452 or (612) 933-8855
NOTE ** FAX: (612) 933-8833
NOTE **
NOTE ** Call for the location of the manufacturer nearest
you.
NOTE **
NOTE ** "Anchor Vertica7," "Anchor Vertica Pro7," "Anchor
Diamond7" and "Anchor Diamond Pro7" modular
concrete wall units ensure proper alignment and
precise set-back without need for mortar or pins
due to their integral alignment feature.
NOTE **
NOTE ** SECTION 02834 - MODULAR CONCRETE RETAINING WALLS,
Copyright 1998, The Architect's Catalog, Inc.
PART 1 GENERAL
1.1 SECTION INCLUDES
A. Modular concrete retaining wall units to the lines and
grades designated on the construction drawings and as
specified herein.
1.2 RELATED SECTIONS
NOTE ** Delete any sections below not relevant to this
project; add others as required.
A. Section 02300 - Earthwork: Excavating, backfilling and
compacting.
B. Section 02900 - Planting.
C. Section 02620 - Subdrainage.
1.3 UNIT PRICES
A. Measurement of segmental retaining wall shall be on an
installed square foot basis computed on the total face
area of installed wall. Face area is from bottom of base
course to top of wall.
B. Payment for retaining wall will be made on a square foot
basis at the Contract Unit Price.
1. Payment shall be considered full compensation for
labor, materials, equipment, and testing required to
install retaining wall in accordance with drawings
and these specifications.
2. Quantities may vary from that shown on drawings,
depending on existing topography; change to total
quantity of wall face area will be paid or withheld
at the Contract Unit Price.
1.4 REFERENCES
NOTE ** Delete references from the list below that are not
actually required by the text of the edited
section.
A. ASTM C 90 - Standard Specification for Load-Bearing
Concrete Masonry Units.
B. ASTM C 140 - Test Methods of Sampling and Testing
Concrete Masonry Units.
C. ASTM C 666 - Standard Test Method for Resistance of
Concrete to Rapid Freezing and Thawing.
D. ASTM D 448 - Standard Classification for Sizes of
Aggregate for Road and Bridge Construction.
E. ASTM D 698 - Standard Test Method for Laboratory
Compaction Characteristics of Soil Using Standard Effort
(12,400 ft-lbf/ft3 (600 kN-m/m3)).
F. ASTM D 1557 - Test Method for Laboratory Compaction
Characteristics of Soil Using Modified Effort (56,000 ft-
lbf/ft3 (2,700 kN-m/m3)).
1.5 DEFINITIONS
A. Backfill: Soil used as fill behind drainage aggregate
and within the reinforced soil mass, if applicable.
B. Drainage aggregate: Material used around and directly
behind concrete wall units.
C. Foundation soil: Soil mass supporting the leveling pad
and reinforced zone of the retaining wall system.
D. Geosynthetic reinforcement: Material specifically
fabricated for use as a soil reinforcement.
E. Wall fill: Free-draining aggregate material used within
and around concrete retaining wall units.
1.6 SUBMITTALS
A. Submit under provisions of Section 01300.
B. Product Data: Manufacturer's printed product literature,
including installation instructions.
C. Shop Drawings: Retaining wall system design including
wall heights, geosynthetic reinforcement and drainage
provisions.
1. Prepared and signed by a registered Professional
Engineer retained by the Installer and licensed in
the State of wall installation.
NOTE ** Delete the following paragraph if samples are not
required.
D. Samples:
1. Furnish one unit in the color and face pattern
specified; approved unit may be used in the work.
2. 12 inches square or larger piece of geosynthetic
reinforcing specified.
E. Test Reports: Submit test reports from an independent
laboratory demonstrating compliance of concrete units
with reference standards.
1. Water absorption and compressive strength tested in
accordance with ASTM C 140, Sections 6,8, and 9.
1.7 DELIVERY, STORAGE, AND HANDLING
A. Inspect the materials upon delivery to assure that
specified products have been received.
B. Deliver and handle materials in manner that will prevent
damage.
1. Store above ground on wood pallets or blocking.
2. Remove damaged or otherwise unsuitable material, when
so determined, from the site.
3. Faces of the modular concrete units shall be free of
chips, cracks and stains.
C. Prevent wet cement, epoxy, excessive mud, etc., from
coming in contact with the materials.
NOTE ** Select one of the following Articles or delete both
Articles if extra materials are not required.
1.8 EXTRA MATERIALS
A. Furnish Owner with matching replacement units comprising
1 percent of those installed on the Project.
B. Furnish Owner with three replacement units identical to
those installed on the Project.
PART 2 PRODUCTS
2.1 MANUFACTURERS
A. Provide products fabricated under license from Anchor
Wall Systems, Inc., 6101 Baker Road, Suite 201,
Minnetonka, MN 55345; ASD. Tel: (800) 473-4452 or (612)
933-8855, FAX: (612) 933-8833.
2.2 MATERIALS
NOTE ** Delete one of the following two sets of paragraphs
headed "Modular Concrete Retaining Wall Units."
The first is for Anchor Vertica and Vertica Pro;
the second is for Anchor Diamond and Diamond Pro.
A. Modular Concrete Retaining Wall Units: High strength,
high density concrete units, freeze-thaw resistant with
top locator providing a 4 degree set back from plane with
each course.
NOTE ** Delete one of the following two paragraphs.
1. Acceptable Product: "Anchor Vertica Pro Retaining
Wall Units".
2. Acceptable Product: "Anchor Vertica Retaining Wall
Units".
3. Comply with ASTM C 90 except provide minimum
compressive strength of 3,000 psi and maximum water
absorption of 7.0 percent.
4. Freeze thaw resistance: In accordance with ASTM
C 666, modified to 50 cycles.
5. Provide units that are positively interlocked with
integral shear connections adequate for design.
6. Minimum weight: 100 pounds per square foot of wall
face, including fill within the units.
NOTE ** Delete one of the following two paragraphs.
7. Minimum exposed face area (Anchor Vertica units):
0.94 square feet.
8. Minimum exposed face area (Anchor Vertica Pro units):
0.94 square feet.
9. Provide units whose dimensions do not vary more than
plus or minus 1/16 inch from that specified, in any
molded dimension.
NOTE ** Delete one of the following two paragraphs.
10. Face geometry: Beveled.
11. Face geometry: Straight.
NOTE ** Delete one of the following two paragraphs.
12. Texture: Smooth.
13. Texture: Rockface.
14. Color: As selected by Architect from manufacturer's
standard selections.
B. Modular Concrete Retaining Wall Units: High strength,
high density concrete units, freeze-thaw resistant.
NOTE ** Delete one of the following two paragraphs.
1. Acceptable Product: "Anchor Diamond Retaining Wall
Units".
2. Acceptable Product: "Anchor Diamond Pro Retaining
Wall Units".
3. Comply with ASTM C 90 except provide minimum
compressive strength of 3,000 psi and maximum water
absorption of 7.0 percent.
4. Provide units with an integral concrete shear
connection flange along the lower rear edge.
NOTE ** Delete one of the following two paragraphs.
5. Minimum exposed face area (Anchor Diamond units):
0.67 square feet.
6. Minimum exposed face area (Anchor Diamond Pro units):
0.94 square feet.
7. Unit height: Not more than plus or minus 1/16 inch
variation from that specified.
NOTE ** Delete one of the following two paragraphs.
8. Face geometry: Beveled.
9. Face geometry: Straight.
NOTE ** Delete one of the following two paragraphs.
10. Texture: Smooth.
11. Texture: Split rock face.
12. Color: As selected by Architect from manufacturer's
standard selections.
C. Geosynthetic Reinforcement: Woven polyester fiber
geogrid, expanded polyethylene sheet geogrid, or woven
polypropylene geotextile.
D. Base:
NOTE ** Delete 2 of the 3 following paragraphs.
1. Drainage aggregate.
2. Sand, specified in Section _____.
3. Concrete, specified in Section 03300.
E. Drainage Aggregate: Free-draining, coarse aggregate
complying with ASTM 448, size no. 57, 67, 6, 7 or 8.
NOTE ** Delete the following paragraph if neither Anchor
Vertica nor Anchor Vertica Pro units are used.
F. Unit Fill: Same materials as drainage aggregate.
NOTE ** Normally, the project engineer or geotechnical
consultant determines whether the soil is suitable
for backfill purposes. Soil types that are not
suitable for modular retaining walls include USCS
Classifications CH, OH, MH, OL, PT, and CL soils
with a Plasticity Index greater than 25.
G. Backfill: On-site soils unless otherwise indicated on
the drawings; where additional backfill is required,
submit sample and specifications to project Geotechnical
Engineer for approval.
NOTE ** Delete the following paragraph if drain tile is to
be installed under another specification section.
For Anchor Diamond, drains are normally required;
for Anchor Vertica, they may not be.
H. Foundation Drain: Perforated or slotted PVC pipe or
corrugated HDPE pipe, covered with geotextile filter
fabric.
PART 3 EXECUTION
3.1 EXAMINATION
A. Examine the areas and conditions under which retaining
walls are to be erected.
1. Notify the Architect in writing of conditions
detrimental to the proper and timely completion of
the work.
2. Notify the Architect in writing of site conditions
which may affect wall performance or may require
reevaluation of wall design.
B. Do not proceed with the work until unsatisfactory
conditions have been corrected.
3.2 EXCAVATION
A. Excavate to the lines and grades shown on the drawings.
Over-excavation will not be compensated for and
replacement with compacted fill or wall system components
will be required at Contractor's expense. Take care not
to disturb base beyond the lines shown.
3.3 FOUNDATION PREPARATION
A. Excavate as required for footing or base dimension shown
on the drawings, unless otherwise directed.
B. Obtain the Geotechnical Engineer's approval of subgrade
to ensure that the actual soil strength meets or exceeds
that required.
C. Remove soil not meeting the required strength, and
replace with acceptable material.
D. Fill over-excavated areas with compacted backfill
material.
NOTE ** Retain the following paragraph for Vertica.
E. Proof-roll foundation soil prior to fill and geosynthetic
reinforcement placement.
3.4 BASE COURSE PREPARATION
NOTE ** Show base depth and width on the Drawings.
Standard minimum base thickness is 6 inches. Edit
the following paragraph, if necessary.
NOTE **
NOTE ** At Contractor's option, designs using reduced depth
of aggregate and 1 to 2 inch concrete toppings may
be used. Concrete shall be lean, unreinforced and
a maximum of 2 inches thick. Where a reinforced
footing is required, place below the frost line.
Show any such footings on the Drawings.
A. Place granular base materials as indicated on the
Drawings, but not less than 6 inches thick.
B. Place and compact base materials to the depths and widths
indicated on the drawings.
C. Place base materials upon undisturbed soils or on
foundation soils properly backfilled.
D. Compact base material to a level, hard surface on which
to place the first course of units.
NOTE ** Edit the following paragraph if required compaction
differs from 95 percent.
1. Compact to 95 percent standard proctor (ASTM D 698).
E. Prepare base materials to ensure complete contact of
retaining wall unit with base material. Do not allow
gaps.
3.5 ERECTION
A. Erect units in accordance with manufacturer's
recommendations and as specified herein.
B. Place first course of concrete wall units on the prepared
base material. Check units for level and alignment.
Ensure that the top of all units in base course are at
the same elevation.
C. Ensure that concrete wall units are in full contact with
base.
D. Place concrete wall units side by side for full length of
wall alignment. Alignment may be done by using a string
line or offset of wall line.
E. Fill all voids between and within concrete wall units
with drainage aggregate.
NOTE ** Delete 1 of the 2 following paragraphs.
NOTE **
NOTE ** Anchor Vertica and Anchor Diamond units require 12
inches of drainage fill.
NOTE ** Anchor Vertica Pro units may require as little as 6
inches of drainage fill.
F. Place at least 12 inches of free-draining aggregate
behind the concrete wall units.
G. Place at least 6 inches of free-draining aggregate behind
the concrete wall units.
H. Install drain tile at lowest elevation possible to
maintain gravity flow of water to outside reinforced
zone. "Daylight" drainage collection pipe to an
approximate location away from wall system at each low
point or at 50 foot intervals along wall.
I. Remove excess fill from top of concrete wall units and
install next course. Ensure that drainage aggregate and
backfill are compacted before installation of next
course.
NOTE ** Delete 1 of the 2 following paragraphs.
NOTE **
NOTE ** Retain only the first for Anchor Vertica and Anchor
Vertica Pro units.
NOTE ** Retain only the second for Anchor Diamond and
Anchor Diamond Pro units.
J. Install each succeeding course so the side slots are in
contact with the locator. Pull the units forward until
the side slot of the unit touches the back of the locator
of the previous course.
K. Pull each unit forward as far as possible until the
locating surface of the unit contacts the locating
surface of the unit in the preceding course.
L. Backfill as each course is completed.
M. Install geosynthetic reinforcement in accordance with
retaining wall manufacturer's design recommendations and
as indicated on drawings.
3.6 BACKFILL PLACEMENT
A. Place, spread, and compact reinforced backfill in a
manner to minimize slack in reinforcement.
B. Place and compact fill in the reinforced zone.
1. Lifts not exceeding 6 to 8 inches in loose thickness
where hand-operated compaction equipment is used.
2. Lifts not exceeding 12 inches in loose thickness
where heavy, self-propelled compaction equipment is
used.
C. Compact fill placed in reinforced zone to minimum 95
percent of soil's standard Proctor density (per ASTM D
698) or as recommended by project Geotechnical Engineer.
D. Allow only lightweight hand-operated equipment within 4
feet of back of retaining wall units, or one-half the
wall height, whichever is greater.
NOTE ** Retain the following Article if applicable.
3.7 CAP UNIT INSTALLATION
A. Apply construction adhesive to the top surface of the
unit below and place the cap unit into desired position.
B. Cut cap units if necessary to obtain the proper fit.
C. Backfill and compact to finish grade.
3.8 FIELD QUALITY CONTROL
A. Retain a qualified independent third party to verify
correct installation of materials in accordance with
drawings and these specifications.
B. Owner, at his own expense, may retain a qualified
professional to perform random quality assurance checks.
C. Correct work found deficient and not in accordance with
drawings and these specifications.
D. Retaining wall will not be considered complete until
accepted by Architect or duly appointed representative of
the Owner.
3.9 ADJUSTING AND CLEANING
A. Replace damaged units prior to Substantial Completion.
B. Remove debris and scrap from the site.
C. Leave adjacent paved areas broom clean.
END OF SECTION