510.02 Earth Reta Ining Systems and Sound Barrier Walls
394 presence of a Department representative. Testing of compressive strength cores will be conducted by the Materials Division in accordance with AASHTO T -22 and the cores must comply with the sample requirements of th e contract documents. Testing of entrained air content cores will be conducted by the Materials Division or its representative in accordance with ASTM C457. The entrained air portion of the total air content must meet or exceed 3.0% for Class A, 3.5% for Class AA, and 2.0% for Class P. Replace concrete sections with less 3.0% entrained air for Class A, 3.5% for Class AA, and 2.0% for Class P. Do not use volumes of concrete with entrained air 10 percent or greater. Except for Class P, replace concrete with less than 3% entrained air (2% for Class P) at no additional cost.
510.01 Description
This work consists of constructing earth retaining systems, sound barrier walls, and slopewalls both cast-in-place and precast.
510.02 Materials
A.General Provide materials in accordance with the following sections and subsections: Material: Section or Subsection: Structural Concrete 509 Reinforcing Steel for Structures 511 Portland Cement Concrete 701 Cover Material for Pipe Underdrains 703.06 Granular Backfill 703.07 Drainage Conduits 726 For cast-in-place earth retaining systems, sound barrier walls, and slopewalls use Class A concrete. For slopewalls, use coarse aggregate for thin section concrete.
B.Precast Elements Provide precast walls (retaining walls and sound walls) from manufacturers certified by the National Precast Concrete Association (NPCA). Use Class AA concrete in accordance with Section 509, “Structural Concrete” for manufacturing precast wall elements.
C.Filter Fabric Provide filter fabric in accor dance with Subsection 712.03, “Geotextiles for Subsurface Drainage Purposes. ” EARTH RETAINING SYSTEMS AND SOUND BARRIER WALLS 510.04 395 D. Granular Backfill for Mechanically Stabilized Earth (MSE) Walls Provide granular backfill for MSE walls in accordance with Subsection 703.07, “Granular Backfill.” Provide backfill material with an internal friction angle of at least 34°. Determine the internal friction angle using the Standard Direct Shear Test in accordance with AASHTO T 236. Test portions of material that pass through a No. 10 [2 mm] sieve. At the optimum moisture content, compact a material sample to 95 percent in accordance with AASHTO T 99, Method C or Method D (with oversized correction). If at least 80 percent of sizes are greater than ¾ in [20 mm] sieve size, the Department does not require testing for backfills. Provide backfill material that meets the following electrochemical requirements if using backfill material with steel soil reinforcement: pH of 5 to 10, Resistivity of ≥ 30 Ω meter, Chlorides: ≤100 ppm, and Sulfates: ≤200 ppm.
510.03 Equipment — Vacant
510.04 Construction Methods
A.General Use construction methods in accordance with Section 501, “Excavation and Backfill for Structures,” Section 502, “Forms, Falsework, and Temporary Works,” Section 509, “Structural Concrete,” Section 511, “Reinforcing Steel for Structures,” and Section 613, “Drainage Conduits. ” for earth retaining systems and noise barrier walls. The Department may allow alternative designs for earth retaining systems and sound barrier walls. Obtain the Engineer’s approval of the working drawings be fore using an alternative design. The Department may allow the use of design methods for structure types or elements not covered by these specifications if documented in published literature, proven adequate through use by expert personnel performing the design for these walls, and if approved by the Engineer.
B.Working Drawings Provide working drawings and design calculations for alternative earth retaining systems and noise barrier walls, or as required by the Contract. Submit drawings in accordance wi th Subsection 105.02, “Plans and Working Drawings,” and include the following: Verification of existing ground elevations for structures involving construction in original ground; The layout of an effective retaining wa ll or noise barrier wall that maintains or surpasses the height and length required by the Contract; Design calculations proving that the design satisfies AASHTO LRFD Specification design parameters including internal, external, overall, and compound stabi lity;
510.04 Earth Retaining Systems and Sound Barrier Walls
396 Details of elements required for the construction of the system, including complete material specifications; Earthwork requirements for retaining walls, including specifications for material and backfill compaction; Details of revisions or additions to drainage systems or other facilities; Other information required by the Contract or requested by the Engineer; For concrete walls that require an architectural finish, show the layout and identify each piece of form liners; and Show the sequence of con struction.
C.Backfill Place backfill material within the lines shown on the Plans. Use the type of granular backfill for retaining walls required in the Contract.
D.Drainage
1.Concrete Gutters Construct concrete gutters to the profile required by the Contract or shown on the Plans. Provide drainage outlets at sags in the profile, the low points of the gutter, and other Contract required locations.
2.Weep Holes Construct weep holes at locations required by the Contract or shown on the Plans. Place a t least 2 ft³ [0.06 m³] of coarse cover material for pipe underdrains encapsulated with filter fabric at the weep holes. Cover joints with filter fabric between precast concrete retaining wall face panels that function as weep holes. Bond the filter fabri c to the face panels in accordance with the manufacturer’s recommendations. Dry the face panels, and clean off dust and loose materials before applying the filter.
3.Drainage Blankets Construct drainage blankets from the following materials: Coarse cove r material for pipe underdrains encapsulated in filter fabric or filter sand, Collector pipes, Outlet pipes, and Cleanout pipes. Compact the subgrade to the Contract required density, and grade it to the elevation shown on the Plans before installing filte r fabric. Remove material and sharp objects that could damage the fabric. Stretch and align the fabric. Smooth -out wrinkles. Overlap adjacent borders from 12 in to 18 in [300 mm to 450 mm]. Repair damaged fabric by covering the area with a piece of fa bric that meets the overlap specifications. Place coarse cover material in horizontal layers, and compact it. The Department will not allow ponding or jetting of the coarse cover material or adjacent backfill. When spreading and EARTH RETAINING SYSTEMS AND SOUND BARRIER WALLS 510.04 397 compacting, maintain at l east 6 in [150 mm] of cover material between the construction equipment and the fabric. Place perforated collector pipes in the cover material to the elevations shown on the Plans. Place outlet pipes at sags in the flow line, the low ends of the collector pipes, and other Contract required locations. Place cleanout pipes at the high ends of collector pipes and locations shown on the Plans.
4.Geocomposite Drainage Systems Install geocomposite drainage systems at the locations required by the Contract or sh own on the Plans. Place and secure geocomposite drainage material against the excavated face, lagging, or back of wall as required by the Contract. Before placing concrete against geocomposite drainage material, protect the drainage material from damage and grout leakage.
E.Wall Systems
1.Cast -in-place Concrete Walls
a.Architectural Finish Complete the following if an architectural finish is used on the exposed wall surfaces is indicated: Submit a sample of the form liner for Engineer approval, with working drawings. Use the least possible number of joints in the form liner. Discard and replace damaged form liner.
b.Retaining Wall Placement Cast retaining walls with a 1 percent batter toward the backfill to compensate for wall deflection unless otherwise required by the Contract. Postpone backfilling until after casting and curing each section within a continuous section of wall in accordance wi th Section 509, “Structural Concrete.”
c.Vertical Precast Concrete Wall Elements with Cast -in-Place Concrete Footings Prevent displacement by bracing wall elements until footing concrete develops the strength to support wall el ements. Complete work in accordance with Section 502, “Forms, Falsework, and Temporary Works.”
2.MSE Walls Ensure the Engineer approves MSE retaining wall systems used on ODOT projects before use. Build a facing system for MSE retaining walls. Connect steel or polymeric soil reinforcement to the facing system. Place structure backfill material around the reinforcement. Design the MSE retaining walls in accordance with the current edition of the AASHTO LRFD Standard Specifications for Highway Bridges , the Contract, and Subsection 105.02, "Plans and Working Drawings." Use MSE retaining walls designed by a Registered Engineer in the State of Oklahoma.
510.04 Earth Retaining Systems and Sound Barrier Walls
398 Design MSE retain ing walls for internal, external, overall, and compound stability. The design and analysis of MSE retaining walls with parapet walls or concrete railing must include the effects of rail load applied at the top of the rail parapet in accordance with the de sign specification. Unless otherwise shown on the Plans, ensure the following for backfill design parameters for MSE retaining walls: A maximum friction angle of 34º when computing horizontal stress in the MSE mass, A cohesion of 0, and Unit weight of at l east 120 lb/ft³ [2,000 kg/ m³]. (Omit "if constructing an MSE precast retaining structure) This section applies to precast MSE structures and it is inferred . Provide a drainage blanket behind and beneath the stabilized zone for MSE precast retaining wall s ystem in cut areas or hill sides with established piezometric levels unless otherwise required in the Contract. Provide adequate drainage to prevent saturation of the stabilized backfill, and divert any surface flows carrying aggressive deicing chemicals away from the MSE structures. Ensure the MSE shop drawings provided by the proprietary wall company show the drainage system, means for diversion of aggressive chemical flows, or both. Allowable longitudinal differential settlements for mechanically stabi lized earth structures are largely a function of panel size and joint design. The Department will allow differential settlements in the longitudinal direction of 1 percent for discrete modular panels less than 30 ft² [2.8 m²] in area with a design joint o f at least ¾ in [19 mm]. Proportionally reduce the allowance for larger panels or for panels with smaller design joints. Allowable transverse differential settlements are a function of reinforcement length, size and ability of the panel connection to rot ate. Control or limit the vertical movements between panel connection and the reinforcement to maintain allowable reinforcement yield strains. Provide additional soil testing if required by the MSE retaining wall design and analysis. Submit a copy of the se calculations, including shop drawings of the retaining wall, to the Engineer for review and approval. The Department requires MSE walls to have a service life of at least 100 years. Design reinforcing elements with a metal area that correlates with the corrosion area expected over 100 years. Base the design section on the area defined by the following equation: AsAnAc where Ac = Area of design section, An = Area of the original reinforcement, and As = Area of the sacrificial section lost to corrosion. Provide data for resistivity, pH, chlorides, and sulfates using Contract required test procedures for the sites. EARTH RETAINING SYSTEMS AND SOUND BARRIER WALLS 510.04 399 Complete service life calculations in accordance with the Federal Highway Administration “Geotechnical Engineering Notebook,” Chapter 5, Section 3, Section 4 for structures exposed to deicing salts. The increased chloride concentration will affect the upper 7.5 ft [2.3 m] of backfill measured from the roadway surface. Submit a copy of these service life calculations to the Engineer for review and approval.
a.Facing Provide facing made of precast concrete panels required by the Contract and shown on the Plans. Provide a Class 2-Rubbed finish or the architectural treatm ent required by the Contract. Ensure the face not exposed to view has a uniform surface finish, no open aggregate pockets, and surface distortion of ¼ in [6 mm] or less. Locate and secure soil reinforcement connection hardware during concrete placement. Prevent contact between hardware and the facing reinforcing steel.
b.Soil Reinforcement Galvanize steel reinforcement and steel connection hardware in accordance with AASHTO M 111 unless otherwise required by the Contract. Form facing mesh by bending th e soil reinforcement mesh to 90º. Connect it to the soil reinforcing mesh above with a pre -bent tie. Provide a backing mat made of 2 in × 6 in [50 mm × 150 mm], W1.7 × W1.7 welded wire fabric meeting ASTM A -185 and in accordance with Subsection 723.03, “Welded Steel Wire Fabric.” Welded wire fabric to be shop fabricated from cold -drawn wire. Wire must conform with AASHTO M 32. Provide backing mat with a height 2 in [50 mm] smaller than the facing mesh height. Retain soil by placing hardware cloth, with openings no greater than ¼ in, between the backfill and backing mat. Galvanize in accordance with AASHTO M 111. To avoid the loss of backfill fines, ensure the hardware cloth extends 3 in [75 mm] beyond the facing mes h height. Inspect reinforcing and attachment devices to ensure they meet Contract size requirements with no defects. Provide shop -fabricated reinforcing wire mesh made of cold drawn steel wire in accordance with Subsect ion 723.07, “Cold Drawn Steel Wire. ” Weld it into the finished mesh fabric in accordance with ANSI/AASHTO/AWS D 1.1, Structural Welding Code -Steel. Galvanize the fabricated mesh. Repair damage to mesh galvanization before installation. Provide a galvan ized coating in accordance with AASHTO M 111. Provide a High Density Polyethylene (HDPE) integrally formed grid structure as a soil reinforcement geogrid. Provide a geogrid with a high tensile modulus relative to the reinforced material, large apertures, thick ribs, and junctions to allow mechanical interlock with the reinforced material. Ensure the geogrid has a high continuity of tensile strength through the ribs and junctions of the structure. The geogrid must resist deformation under sustained long term load, ultraviolet degradation, and biological or chemical degradation in the reinforced
510.04 Earth Retaining Systems and Sound Barrier Walls
400 material. The geogrid must at least meet the physical property requirements of Type 2 Subsection 712.07, “Geogrid Subgrade Rei nforcement of Pavement Structures.” Use ½ in [13 mm] diameter Schedule 80 polyvinyl chloride plastic pipe, ASTM D 1785, or a ½ in × ¼ in [13 mm × 6 mm] HDPE bar as connector pins at each geogrid splice. Make tie strips of hot rolled steel Grade 50 or equi valent in accordance with AASHTO M 270. Make 1 -inch [25 mm] coil embed of cold drawn steel wire in accordance with AISI C1035. Galvanize in accordance with ASTM B 633. Fill the cavity of the coil embed with no-oxid grease, or an equivalent approved by t he Engineer. Provide a 1 in [25 mm] diameter coil bolt with 2 in [50 mm] of thread, cast of 80 -55-06 ductile iron in accordance with ASTM A 536. Galvanize in accordance with ASTM B 633. Ensure fasteners consist of hexagonal cap screw bolts and nuts, with a ½ in [13 mm] diameter, galvanized in accordance with AASHTO M 164. Make connector pins and mat bars for the Reinforced Soil Embankment system from ASTM A 709 Grade 36 (AASHTO M 270). Weld to the soil reinforcement mats as shown on the Plans. Cold form p anel anchors of cold drawn wire in accordance with ASTM A 1064/A1064M (AASHTO M 32). Galvanize anchors after forming. Provide polymeric reinforcement of the type and size required by the Contract or shown on the working drawings. Provide connection hardw are as required by the Contract or shown on the working drawings.
c.Construction Install joint filler and water stops to the dimensions and thicknesses shown on the Plans and in accordance with subsection 518.04B, “ Water Stops .” Install 18 in [450 mm] wide strips of filter cloth on the back face of the panel, over the panel joints. To secure the cloth, apply an adhesive compound to the back face of the panel. Provide and install one of the following: Preformed cork in accordance with AASHTO M 153 Type II, Preformed EPDM rubber pads in accordance with ASTM D 2000 for 4AA, 812 rubbers, or Neoprene (polychloroprene) elastomeric pads with a Durometer Hardness from 50 to 60 in horizontal joints between panels. Grade the structure foundation level for a width at least the length of reinforcement elements, plus 1 ft [300 mm], or as shown on the Plans. Before constructing the wall, compact the foundation using two passes of a vibratory drum compactor except where the wall i s constructed on rock. Replace unacceptable foundation soils below the footing elevation with concrete or Controlled Low -Strength Material (CLSM) at no additional cost to the Department. Provide the type of a cast -in-place unreinforced concrete leveling pad at each panel foundation shown on the Plans. Cure the leveling pad for at least 12 hr before placing wall panels. Provide the pad with at least 2 ft [600 mm] of backfill cover. EARTH RETAINING SYSTEMS AND SOUND BARRIER WALLS 510.04 401 Ensure a field representative from the chosen proprietary wall system is available during wall erection. Provide the representative’s services at no additional cost to the Department. Place panels with lifting devices connected to the upper edge during erection in successive horizontal lifts during backfill placement in the se quence shown on the Plans. When placing backfill material behind the panels, hold the panels in a vertical position with temporary wedges or bracing in accordance with the recommendations of the wall supplier. For structures with precast facing panels, e nsure that concrete vertical tolerances and horizontal alignment tolerances do not exceed ¾ in [19 mm] when measured with a 10 ft [3 m] straight edge. During construction, prevent panel offset from surpassing ¾ in [19 mm]. Maintain an overall vertical wal l tolerance of no more than ½ in [12.5 mm] per 10 ft [3 m] in height. Check the plumb and tolerances of the panel row at the face before erecting the next panel row. For panels that do not meet the Contract required tolerances, remove the backfill and re set the panels. Ensure uniform horizontal, vertical, and slope joints with openings between panels from½ in to 1¼ in [13 mm to 30 mm] wide. For wire -faced structures, place backing mats and ¼ in [6 mm] hardware cloth in successive horizontal lifts in the sequence shown on the Plans during backfill placement. Ensure the horizontal alignment tolerance and plumb do not exceed 2 in [50 mm] when measured at the junction of the wire facing and soil reinforcement along a 10 ft [3 m] straightedge. Ensure the ov erall vertical tolerance of the wall does not exceed 1 in per 10 ft [25 mm per 3 m] of wall height. Apply these criteria to vertical and battered structures. Place reinforcement elements normal to the wall face, unless otherwise shown on the Plans. Befo re placing the reinforcing elements, compact backfill as specified by the backfill placement procedures shown on the Plans. Place backfill immediately after erecting each course of panels. Do not damage or disturb the wall materials, or misalign the facin g panels. Replace damaged wall materials at no additional cost to the Department. Correct misalignment or distortion from placing backfill outside the Contract required limits at no additional cost to the Department. Compact backfill to 95 percent of th e maximum density in accordance with AASHTO T 99, Method C or Method D (with oversize correction as specified in Note 7), or as shown on the Plans. Before and during compaction, uniformly distribute the moisture of the backfill material throughout each la yer. Remove and rework backfill material with a placement moisture content greater than optimum. Place backfill layer in 6 in [150 mm] or less lifts. Use a lightweight mechanical tamper, roller, or vibratory system for compaction within 3 ft [1 m] of the backface of the wall using at least three passes of a lightweight mechanical tamper, roller, or vibratory system. At the end of each work day, slope the last level of backfill away from the wall to direct runoff. Prevent surface runoff from entering the wall construction site.
F.Slopewalls Construct slopewalls in accordance with Section 610, “Concrete or Asphalt Sidewalks, Driveways, Dividing Strip, and Tactile Warning Devices.” The Department will not allow the placement of horizontal construction joints in the slopewalls. Space vertical construction joints less than 10 ft [3 m], measured along the top of slopewall. The Engineer will determine the final number and location of construction joints in the field.
510.06 Earth Retaining Systems and Sound Barrier Walls
402 G. Sound Barrie r Walls
1.Cast -in-Place Sound Barrier Wall Construct cast -in-place sound Barrier walls in accordance with Section 509, “Structural Concrete, ” Section 511, “Reinforcing Steel for Structures ,” and Section 516, “Drilled Shaft Foundations.” If an architectural finish on the exposed wall surfaces is shown on the Plans, complete the following: Submit a sample of the form liner for Engineer approval, with working drawings. Use th e least possible number of joints in the form liner. Discard and replace damaged form liner.
2.Pre-cast Sound Barrier Walls Design the Pre -cast Sound Barrier Walls in accordance with the current edition of the AASHTO Guide Specification for Structural D esign of Sound Barriers, the Contract, and Subsection 105.02, "Plans and Working Drawings. " Use pre -cast sound barrier walls designed by a Professional Engineer registered in the State of Oklahoma. Ensure the Engineer designed the pre -cast sound barrier walls for external and internal stability. Construct pre -cast sound barrier wall in accordance with Section 509, “Structural Concrete,” Section 511, “Reinforcing Steel for Structures, ” and Section 516, “Drilled Shaft Foundations.” The Department will allow a final tolerance of ⅛ in per 12 in for level and plumbness.
510.05 Method of Measuremen T
The Engineer will measure the area of Retain ing Wall , Sound Barrier Wall , and MSE Retaining Wall from the top of footing to the wall top. The Engineer will measure the area of Slopewall in accordance with the dimensions shown on the Plans.
510.06 Basis of Payment
The Department will pay for each pay item at the contract unit price per the specified pay unit as follows: Pay Item: Pay Unit:
A.RETAINING WALL Square Yard [Square Meter]
B.SOUND BARRIER WALL Square Yard [Square Meter]
C.SLOPEWALL Square Yard [Square Meter]
D.MSE RETAINING WALL Square Yard [Square Meter] REINFORCING STEEL FOR ST RUCTURES 511.02 403 The Department will consider the cost of the following to be included in the contract unit price for relevant wall pay item: Engineering and associated costs, Excavation, Backfill, Backfill material, Concrete, Reinforcing ste el, Form liners, Perforated pipe underdrain, Geocomposites, Filter fabric, Pipe underdrain cover material, Concrete surface finish, and Sheeting and shoring. The Department will pay for drilled shafts and piling required by the Contract in accordance with Section 516, "Drilled Shaft Foundations," and Section 514, "Driven Foundation Piles," respectively. SECTION 511 REINFORCING STEEL FOR STRUCTURES
511.01 Description
This work consists of providing and placing reinforcing steel.
511.02 Materials
A.General Provide reinforcing steel consisting of deformed bars, epoxy -coated deformed bars, and cold -drawn wire mesh. Provide reinforcing steel in accordance with Section 723, “Reinforcing Steel.” Ensure the strength requirements are in accordance with Grade 60 (420), unless otherwise required by the Contract. Provide cold -drawn wire for spiral ties and other reinforcing designated in W (wire) sizes.
B.Bar Lists and Bending Diagrams Use the bar list and bending diagrams in the Contract to estimate quantities. Ensure bent bars are dimensioned out -to-out. Before ordering, ver ify and correct the quantity, size, and shape of the bar reinforcement. If the bar list and bending diagram are not included in the Plans, create and submit them for the Engineer’s approval in accordance with Subsection 105.02, “Plans and Working Drawings. ” Obtain the Engineer’s approval before constructing vertical reinforcement in columns, walls, and piers.
Source: Oklahoma Standard Specifications for Highway Construction, 2019 Edition. Pages 408–416 of 935.