732.01Description
This work shall consist of design as re quired, furnishing materials, and placement of modular block wall units in accordance with 105.03. The modular block wall unit shall have ground reinforcement if shown on the plans or required by the manufacturer.
732.02General Design Requirements
The modular block wall shall consist of an aggregate leveling pad, concrete modular block wall units, and if specified, ground reinforcement elements. Ground 10 reinforcement shall have sufficient strength, frictional resistance, and quantity as required by design, and shall be frictionally or mechanically connected to the facing units.
Modular block wall units shall be constructed as shown on the approved working drawings based on the requirements herein. The recommendations of the wall system supplier shall not override the minimum performance requirements shown herein.
732.02
The top of the modular block wall shall be designed to prevent the removal of the top course of blocks. 20
If the wall system provider needs additional information to complete the design, the Contractor shall be responsible for obtaining such information.
All appurtenances behind, in front of, under, mounted upon, or passing through the wall such as drainage structures, utilities, or other appurtenances shown on the plans shall be accounted for in the stability design of the wall.
The modular block wall design shall follow the general dimensions of the wall envelope shown on the plans. The working drawings shall show the location of the 30 leveling pad at or below the theoretical leveling pad elevation shown on the plans. The top of the modular block wall unit shall be at or above the top of the wall elevation shown on the plans.
Cast-in-place concrete will not be an acceptable replacement for modular block wall unit areas indicated by the wall envelope.
Modular block wall units shall be de signed to accommodate a differential settlement of 1 linear unit in 100. Where shown on the plans, slip joints to accommodate excessive or differential settlement shall be included. 40
Only one typical modular block face finish shall be used per contract.
732.03Design Criteria
The maximum modular block wall unit face area shall be 1 sq ft. The minimum depth of modular block wall units shall be 9 in.
Modular block wall units shall be dry stacked in a running bond configuration. Vertically adjacent un its shall be connected with an approved shear connection. Approved shear connections consist of steel pins, concrete lips on the blocks, or other 50 connections as approved by the Engineer.
The internal stability sha ll be the responsibility of the Contractor. The design for internal stability shall be in accordance with the AASHTO LRFD Bridge Design Specifications. The design by the Engineer will consider the external stability of the modular block wall mass including the applied bearing pressure, overturning, sliding, and stability of temporary construction slopes.
The theoretical failure plane within the soil mass shall be analyzed so that the soil-60 stabilizing component extends sufficiently beyond the failure plane to stabilize the material. External loads which affect the internal stability such as those applied through piling, bridge footings, traffic, crashwall, or slope surcharge, shall be accounted for in the design. The sizes of all structural elements shall be determined 732.03
such that the design load stresses do not ex ceed the factored stresses shown in the AASHTO LRFD Bridge Design Specifications.
7KHLQWHUQDOIULFWLRQDQJOHijIRUWKHLQWHUQDOGHVLJQRIWKH PRGXODUEORFNZDOO EDFNILOOYROXPHVKDOOEHDVVXPHGWREH7KHijRIWKHEDFNIL OOEHKLQGWKHPRGXODU block wall backfill volume shall be assum HGWREH7KHijIRUWKHLQWHUQDOGHVLJQ70 of the foundation soils shall be assumed to be 30°. For the external design parameters, such as but not limited to, bearing capacity , sliding, overturning, eccentricity, and global stability, the actual soil strength parameters used shall be obtained from the geotechnical report.
The minimum embedment at the front face of the wall shall be in accordance with the AASHTO LRFD Bridge Design Specifications, section 11.10.2.2, and the minimum embedment depth to the top of the leveling pad shall be at least 3 ft unless founded on rock. A 4 ft horizontal bench in front of the wall shall be provided for slopes steeper than 4.0H:1.0V. 80
The factored applied bearing pressures under the stabilized mass for each reinforcement unit’s length shall be indicated on the working drawings. It shall not exceed the maximum factored soil bearing resistance shown on the plans. Passive pressure in front of the wall mass shall be assumed to be zero for design purposes.
The wall limits shall be defined by the wall envelope shown on the plans.
H, shall be measured from the theoretical top of the leveling pad to the top of the coping or to the gutter line of the traffic barrier. The top of the wall shall be the theoretical top of the face panels only where a coping or barrier is not used.
wall, Z, shall be measured from the theoretical top of the leveling pad to a point above the top of the wall as calculated from the formula as follows:
Z = H + 0.3H tanȕ 1- 0.3 tanȕ
where: ȕ surcharge slope angle as measured from the top of the coping, and H = height of the wall from the theoretical top of the leveling pad to the top of the coping.
732.03
measured from the theoretical top of the leveling pad to the top of the roadway surface.
The ground reinforcement length shall be the controlling length resulting from the internal or external design or as shown on the plans. All ground reinforcement shall 110 extend to and shall be connected to the modular block wall units.
The ground reinforcement shall be the same length from the bottom to the top of each wall section regardless of the type of ground reinforcement used. Differing ground reinforcement elements shall be marked for ease of construction. This element may be used individually or in a prefabricated grouping.
The ground reinforcement for modular block wall sections shall be sized using the lesser of the factored loads for each specific connection and each specific reinforcing element. The connection’s applied factored load and effective pullout 120 length shall be determined in accordance with the AASHTO LRFD Bridge Design Specifications.
For mats, grids, or strip steel, the minimum zinc coating thickness shall be 2 oz/sq ft. Such thickness shall be assumed to be 4 mils for purpose of calculation of reduced structural section.
Where the presence of opposing walls limits the length of ground reinforcing, the design shall account for the reduced length and internal and external stability calculations shall be made to check for adequate factor of safety. 130
732.04Submittals
The Contractor shall submit working drawings and design calculations in accordance with 105.02. Wall construction operations shall not begin until the Contractor receives written notice that the working drawings are approved.
quantities, cross-sections, and general notes necessary to construct the wall and shall include, but shall not be limited to the following:
placing position and connection of all ground reinforcing elements in areas where piling, utility, or other structures are near the wall.
construction centerline to the face of the wall at all changes in horizontal alignment.
732.04
vertical break points at least every 50 ft along the face of the wall
in length of the ground reinforcement occur
maximum bearing pressures.
construct the element and the location of soil reinforcing system devices embedded in the units. 170
the outletting of internal drainage from the modular block wall volume.
such as piles, catch basins, landscape plantings where the bottom of the root ball extends below the top level of ground reinforcement, 180 and other obstructions.
wall unit and the ground reinforcement.
MATERIALS
732.05Materials
Materials shall be in acco rdance with the following:
Admixtures for Concrete* ........................................... 912.03 Air Cooled Blast Furnace Slag .................................... 901.09 B Borrow ..................................................................... 211.02 Coarse Aggregate, Class A or Higher, Size No. 91 ..... 904.03 Coarse Aggregate, Class D or Higher, Size No. 8 ....... 904.03 732.05
Fine Aggregate, Size No. 23 ........................................ 904.02 Fly Ash ........................................................................ 901.02 Geogrid, Type III ......................................................... 918.05 Geotextile .................................................................... 918.02 200 Portland Cement .......................................................... 901.01(b) Structure Backfill ........................................................ 211.03.1 Water ........................................................................... 913.01
* Admixtures in accordance with ASTM C1372 may be used for the modular block if approved by the Engineer.
Aggregate for the leveling pad shall be compacted aggregate No. 53 and shall be in accordance with applicable requirements of 303. Drainage fill used immediately behind the modular block wall, as shown on the plans, shall be coarse aggregate No. 8 crushed stone in accordance with 904.03. 210
Backfill material used in the modular bl ock wall volume shall be structure backfill Type 3 in accordance with 211. Where ground reinforcement is required, nominal size aggregate No. 30 shall not be used. The size of the structure backfill selected for use in the reinforced area of the modular bloc k volume shall remain the same for that wall’s volume. If coarse aggregate No. 8 is used, and soil, B borrow, structural backfill, or coarse aggregate No. 53 are to be placed above the coarse aggregate No. 8, a single layer of geotextile shall be placed on top of the coarse aggregate No. 8 in accordance with 616.11.
If ground reinforcement is required, it shall be either steel in accordance with
910.07or geogrid. The ground reinforcement supplied shall be the same type as that
used with the pullout test and shall be consistent throughout the contract work. If the ground reinforcement is steel, structure backfill shall be in accordance with the backfill
requirements for retaining wall systems contained in 211.03.1.
Concrete modular block retaining wall units shall be in accordance with ASTM
C1372, except for the modifications below, and shall have a minimum compressive
strength of 4,000 psi at 28 days. Modular block wall units utilizing Type I or Type II230
cement will be considered acceptable for placement in the wall when 7-day strengths
exceed 3,500 psi. The modular block wall unit’s compressive strength shall be
considered acceptable regardless of curing age when compressive test results indicate
that the compressive strength is in accordance with the requirements stated above.
Retarding agents, accelerating agents, coloring pigments, or additives containing
chloride shall not be used without approval.
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requirements of 732.05 in lieu of Section 4.
732.05
847
modified to require that the average compressive strength,
when sampled and tested in accordance with ASTM C140,
of a three CMU compressive strength sample shall be 4,000
psi with no individual unit less than 3,500 psi. Maximum
absorption shall be 6%.
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accordance with Section 8.3 by a laboratory qualified by the
Department. Test results on all mix designs used in the
manufacture of modular blocks shall have been completed
in accordance with ASTM C1372. If a change to the mix
design, such as proportioning or material source, is desired,
the modified mix design shall be retested for freeze-thaw. A
Type A certification in accordance with 916 shall be
provided for the blocks. The result of the freeze-thaw
durability test shall be shown on the certification for the260
blocks.
will be conducted by the Engineer in accordance with
ASTM C140. If the compressive strength test result does not
meet the requirements of 732.05(a), the production lot units
may not be used. The manufacturer may resample the same
production lot in the presence of the Engineer for retesting.
The Engineer will test the additional samples in accordance
with ASTM C140. If the retested samples meet the270
requirements of 732.05(a), the production lot may be used.
If the retested samples do not meet the requirements of
(a), all the units from the production lot may not be
used.
Units shall be subject to rejection due to failure to be in accordance with the
requirements specified above. In addition, the following defects may be sufficient
cause for rejection.
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concrete.
as broken or chipped concrete, or color variations, or
dunnage marks on the front face due to excessive form oil
or other reasons.
732.05
848
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The Engineer will determine whether spalled, honeycombed, chipped, or
otherwise defective concrete shall be repaired or be cause for rejection. Repair of
concrete, if allowed, shall be completed in a satisfactory manner. Repair to concrete
surfaces, which are to be exposed to view after completion of construction shall be
subject to approval.
The date of manufacture, the production lot number, and the place mark shall be
clearly scribed on the rear face of each unit or on each shipping pallet.
300
All modular block wall units shall be handled, stored, and shipped so as to
eliminate the danger of chipping, cracks, fractures, and excessive bending stresses.
CONSTRUCTION REQUIREMENTS
732.06General Requirements
The wall supplier representative shall provide technical instruction, guidance in310
pre-construction activities including the pre-construction conference, and on-site
technical assistance to the Contractor during construction.
732.07Foundation Preparation
The foundation for the modular block wall shall be graded level for the width
shown on the plans. Foundation preparation shall otherwise be in accordance with
731.07
At each foundation level, an aggregate leveling pad shall be provided as shown
on the plans.320
732.08Retaining Wall Excavation
Excavation shall be in accordance with 731.08.
732.09Wall Erection
Modular block wall units shall be stored to minimize contact with the ground or
being covered by standing water. Modular block wall units having face discoloration
shall not be used.
The Contractor shall perform the necessary work to verify that the foundation is330
at the correct elevation, that the wall is constructed to the correct alignment, and that
the work is in accordance with the specified tolerances.
Modular block wall units shall be placed in successive horizontal lifts in the
sequence shown on the plans as backfill placement proceeds. As backfill material is
732.06
849
placed behind the units, the units shall be maintained in vertical position. Horizontal
alignment tolerances shall not exceed 3/4 in. when measured with a 10 ft straightedge.
Alignment shall be checked at each layer of modular block wall units after the backfill
behind the modular block wall units has been compacted, and the results shall be
recorded. Checking of alignments and tolerances shall include verifying that the340
modular block wall units are plumb over the entire height of the wall.
Ground reinforcement shall be placed normal to the face of the wall, unless
otherwise shown on the plans and shall be constructed in accordance with 214.04.
732.10Backfill Placement
Backfill placement shall follow erection of each course of modular block wall
units. All sheeting and bracing shall be removed as the backfilling progresses. Backfill
shall be placed to avoid damage or disturbance to the wall materials or misalignment
of the modular block wall units. All material for backfill shall be subject to approval350
and shall be free from large or frozen lumps, wood, or other undesirable material. Wall
materials that become damaged or disturbed during backfill placement shall be
removed and replaced or corrected as directed. All misalignment or distortion of the
modular block wall units due to placement of backfill outside the limits described
herein shall be corrected as directed.
The work shall also include backfilling beyond the theoretical length of the
ground reinforcement in accordance with the details shown on the plans, and the
disposal of surplus of unsuitable excavated materials, as allowed.
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Backfill placement and compaction shall otherwise be in accordance with 731.11.
732.11Method of Measurement
The measurement of concrete modular block wall units with or without ground
reinforcement and wall erection will be based on the square foot area contained within
the neat line limits of the wall envelope shown on the plans and not that of the wall
system supplier.
Common excavation will be measured by the cubic yard in accordance with
203.27(a) to the neat lines shown on the plans. Structure backfill and B borrow will be370
measured in accordance with 211.09. Unsuitable foundation materials, if found, will
be measured in accordance with 211.09. Coarse aggregate No. 8 used as drainage fill
will be measured by the cubic yard based on the theoretical volume to the neat lines
as shown on the plans. Compacted aggregate No. 53, and ground reinforcement will
not be measured. Geotextile materials will not be measured. Drainage of the backfill
including piping and geotextile materials used in the drainage system will not be
measured.
732.12Stockpiled Modular Block Units
Partial payment may be made for block wall units stockpiled on the project site or380
at the Contractor’s approved storage location. Partial payment will include the
732.12
850
delivered cost of the units, as verified by invoices that include freight charges. The
Contractor shall furnish the invoices. The partial payment will not exceed 75% of the
contract unit price for modular block wall with or without ground reinforcement. Prior
to authorizing partial payment, the Engineer will verify that the units are in accordance
with 732.05(a).
732.13Basis of Payment
The accepted quantities of modular block wall units with or without ground
reinforcement will be paid for at the contract unit price per square foot. Erection of390
modular block wall units will be paid for by the square foot. Common excavation will
be paid for in accordance with 203.28. Structure backfill and B borrow will be paid
for in accordance with 211.10. Unsuitable foundation materials will be paid for in
accordance with 211.10. The accepted quantities of coarse aggregate No. 8 used as
drainage fill will be paid for as aggregate for drainage fill at the contract unit price per
cubic yard, complete in place.
Payment will be made under:
Pay Item Pay Unit Symbol400
Aggregate for Drainage Fill....................................................... CYS
Modular Block Wall Erection.................................................... SFT
Modular Block Wall with Ground Reinforcement .................... SFT
Modular Block Wall .................................................................. SFT
The cost of designing the wall system, services including the testing laboratory,
certified testing personnel, and the testing and inspection of modular block wall units
shall be included in the cost of the pay items of this section.
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The cost of materials, ground reinforcement if required, fasteners, cutting or
altering the ground reinforcement at the site, repair or replacement of units damaged
or removed due to backfill placement, compressive-strength retesting if required,
retesting or replacing failed block units, and incidentals shall be included in the cost
of the pay items of this section.
The cost of all labor and materials required for preparing the wall foundation,
compacted aggregate No. 53, coarse aggregate No. 8 placed outside the neat lines as
shown on the plans, replacement materials damaged during backfill placement if
required, and erecting the modular block units shall be included in the cost of wall420
erection.
The cost of all labor and materials for geotextiles shall be included in the cost of
the pay items of this section.
732.13
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