626.1-DESCRIPTION: This work shall consist of furnishing the design, wall construction plans, materials, and construction of cast-in-place reinforced concrete or Mechanically Stabilized Earth (MSE) walls in accordance with these specifications and in reasonably close conformity with the lines, grades, design, and dimensions shown in the plans. 626.2-GENERAL: Unless specified otherwise in the contract documents the wall may be, a t the Contractor’s option, any one of the wall systems on the approved source list corresponding to the applicable Pay Item; this list is posted on the MCS&T web page under the heading Approved Source/Product Listing. The Contractor shall indicate which wall system is to be constructed by the bid alternative chosen in the proposal. No change of the wall system indicated in the bid proposal shall be permitted after the bid opening unless approved by the Engineer. The wall design and detail plans for con struction shall be submitted to the Engineer for approval. The time required for preparation and review of these submittals shall be charged to the allowable contract time. Delays caused by untimely submittals or insufficient data will not be considered justification for time extensions. No additional compensation will be made for any additional material, equipment, or other items found necessary to comply with the project specifications as a result of the Engineer’s review. The proposed wall design shall be compatible with the Contractor’s proposed method of construction, and shall be compatible with any method of construction shown in the plans. The Division does not assume nor warrant any wall system ’s compatibility with any particular construction methods. 626.3-DESIGN CRITERIA: 626.3.1-General: The size of all structural elements shall be determined such that the design load stresses do not exceed the allowable stresses found in the AASHTO LRFD Bridge Design Specifications, latest edition. Analysis of external stability of the in-place retaining wall system will be the responsibility of the Division. Any staged or temporary construction affecting wall stability shall be the responsibility of the Contractor. The parapets on any portion of the retaining walls as shown in the plans shall be desi gned to resist traffic loads in accordance with the AASHTO LRFD Bridge Design Specifications, latest edition. 626.3.2-Mechanically Stabilized Earth: The design for the MSE wall shall consider the internal stability of the wall mass. The design shall co nform to the requirements found in AASHTO LRFD Bridge Design Specifications, latest edition. External loads, which affect the internal stability such as those, applied through piling, bridge footings, temporary construction, etc. shall be accounted for i n the design. A design life of 100 years shall be used throughout the design. The factor of safety for pullout resistance shall not be less than 1.50 based on pullout resistance at ¾ inch deflection. The allowable bearing pressure under the stabilized mass shall be as shown in the plans. The minimum length of the soil reinforcing system, as measured from the back of the front face to the end at the back of the soil stabilized mass, shall be as shown in plans, and shall be the same from top to bottom of the wall at any cross section. All appurtenances behind, in front of, under, mounted upon, or passing through the wall such as drainage structures, utilities, or other items shown in the plans must be accounted for in the design of the wall. 626.3.3-Cast-in-Place Reinforced Concrete: When a Cast-in-Place Reinforced Concrete option is included in the plans the following shall be applicable. The information shown in the plans for the cast-in-place alternative is schematic; however, all dimensions shown in the plans shall be considered minimums. The allowable bearing pressure of the foundation soils, the unit weight of the retained soils, and the characteristics of the retained soils necessary for design purposes shall be as shown in the plans. 626.4-SUBMITTALS: 626.4.1-General: The Contractor shall submit complete design calculations, explanatory notes, and detail plans for the proposed wall system. The detail plans shall include all details, dimensions, quantities, and cross sections necessary to construct the wall and shall include but not be limited to the following items: A plan and elevation sheet or sheets for the wall which shall contain the following:
1.An elevation view of the wall which shall indicate the elevations at the top of the wall at all horizontal and vertical break points and at least every fifty (50) feet along the face of the wall, all steps in the footings or leveling pads, the original and final ground lines, the maximum bearing pressures, and the summary of quantities for each wall.
2.A plan view of the wall which shall indicate the offsets from the construction centerline to the face of the wall at all changes in horizontal alignment and the centerline of any drainage structure or drainage pipe behind, passing through, or under the wall.
3.A typical cross section or cross sections showing elevation relationship between existing ground conditions and proposed grades.
4.All general notes required for constructing the wall. The required batter to compensate for the elongation of the soil reinforcing during erection shall be shown for each different required height.
5.All horizontal and vertical curve data affecting the wall.
6.All details for footings or leveling pads shall be shown including details for steps in the footings or leveling pads.
7.All details for construction of walls with appurtenances behind, under, mounted upon, or passing through the wall such as drainage structures or utilities shall be clearly indicated.
8.The wall manufacture shall submit copies of their Quality Assurance/Quality C ontrol Manuals on each project.
9.Required architectural treatments shall be as indicated and as detailed in the plans. All details for any required architectural treatments shall be shown including:
a.Product data and installation instructions for manufactured form systems, form liners, release agents, ties, and accessories. The release agent manufacturer shall certify that the products supplied comply with regulations controlling the use of volatile organic compounds (VOC’s).
b.Shop drawings for fabrication and erection. These drawings shall show all items that visually affect the exposed concrete, including, but not limited to, general form construction, jointing, specially formed joints or reveals, and patterns of placement. The Engineer’s review will be for general architectural applications and features only. Formwork design for structural stability and sufficiency is the Contractor ’s responsibility and shall not be submitted for the Engineer's review.
c.Mockup or Sample Facing elements. The Contractor shall construct a mockup or sample facing element using the proposed formwork and facing materials in order to demonstrate the required finishes and textures. Actual construction of concrete shall not proceed until the Engineer has accepted the sample units. At the time the detail plans are submitted for review, they shall be accompanied by design calculations and explanatory wall notes. These documents shall be legible and shall demonstrate that the design criteria have been met. Specified minimum factors of safety and the maximum soil pressure beneath the wall footing or earth stabilized mass shall be clearly indicated. The plans shall be prepared on reproducible sheets twenty-two ( 22) thirty- four (34) inches including borders. Each sheet shall have a title block in the lower right hand corner. The title block shall include the sheet number of the drawing, name or designation of the wall, the state and federal project desi gnation, project name, fabricator and Contractor name. Design calculations and notes shall be prepared on sheets 8½ x 11 inches, and shall contain the project designation, wall designation, date of preparation, initials of designer and checker, and page number at the top of the page. The Detail Plans, Design Calculations, and Explanatory Notes shall be signed and stamped by a Professional Engineer registered in West Virginia and knowledgeable in the proposed alternative wall system. The initial submission shall include three sets of the detail plans, calculations, and notes. One set of notes and plans will be returned to the Contractor with any indicated corrections. When the plans and notes are stamped approved by the Engineer, the Contractor shall fu rnish the Engineer with the requested number of sets of prints and a Mylar set of the plans for distribution by the Division. The Contractor shall perform no work or ordering of materials for the structures until the Engineer has approved the submittal. 626.4.2-Mechanically Stabilized Earth: The details and material specifications for the wall facing elements and incidental accessories shall be included with detail plans for approval by the Engineer. The designation as to the type of facing element, the length of the soil reinforcing systems, the distance along the face of the wall where changes in lengths of the soil reinforcing systems occur, and the limit of mesh, strip, or anchor shall be clearly shown in the plans. All wall facing elements shall be detailed. The details shall show all dimensions necessary to construct the element, all reinforcing steel in the element, and the location of soil reinforcing system devices embedded in the elements. 626.4.3-Cast-in-Place Reinforced Concrete : The plans for the cast -in-place wall shall contain a complete reinforcing bar schedule showing all bending details and bar marks. The plans shall also show the location of all construction joints, expansion joints, or other joints in the wall. All wall thickness shall be shown and transition details at wall thickness changes. 626.5-MATERIALS: 626.5.1-Mechanically Stabilized Earth Components: The Contractor shall make arrangements to purchase the facing elements, reinforcing mesh or strips, attachment devices, x joint materials, and all other necessary components. Materials not conforming to this section of the specifications or from sources not listed in the contract documents shall not be used without written consent from the Engineer. 626.5.1.1-Facing Elements: 626.5.1.1.1-Reinforced Concrete Facing Elements: The facing elements shall be fabricated in accordance with Section 601 of the Spe cifications with the following exceptions and additions:
A.Concrete for the reinforced concrete facing elements shall attain a minimum compressive strength of 4,000 psi at 28 days. All concrete shall have air entrainment of 7 % plus or minus 2.5 % with no o ther additives. Specified concrete properties are to be tested in accordance with applicable provision of Section 601.4.1 of the Specifications. Acceptance of a Production Lot will be made if the compressive strength test result is greater than or equal to, 4,000 psi. A Production Lot is defined as a group of panels that will be represented by a single compressive strength test result is greater than or equal to, 4,000 psi. A Production Lot is defined as a group of elements that will be represented by a single compressive strength sample and will consist of a single day’s production. A minimum of two cylinders shall be required for every compressive strength sample.
B.The units shall be fully supported until the concrete reaches a minimum compressive strength of 1,000 psi.
C.Unless otherwise indicated in the plans or elsewhere in the specifications, the concrete surface for the front face shall have a Class 1 finish as define by Section
601.11 and a uniform surface finish for the rear face. The rear face of the element
shall be screeded to eliminate open pockets of aggregate and surface distortions in excess of ¼ inch. The panels shall be cast on a flat area. The clevis loops, tie strip guide, or other galvanized devices shall not contact or be attached to the face element reinforcement steel.
D.The date of manufacture, the production Lot number, and the piece mark shall be clearly scribed on an unexposed face of each element.
E.All units shall be handled, stored, and shipped in such a manner as to eliminate the dangers of chipping, discoloration, cracks, fractures, and excessive bending stresses. Elements in storage shall be supported in firm blocking to protect the element connection devices and the exposed exterior finish.
F.All units shall be manufactured within the following tolerance:
1.Element Dimensions: Position of element connection devices within one (1) inch, except for coil and loop embeds which shall be 3/16 inch. All other dimensions within 3/16 inch.
2.Element Squareness: Squareness as determined by the difference between the two diagonals shall not exceed ½ inch.
3.Element Surface Finish: Surface defects on smooth formed surfaces measured over a length of five (5) feet shall not exceed ¼ inch. Surface defects on the textured-finished surfaces measured over a length of five (5) feet shall not exceed 5/16 inch. Units shall be rejected because of failure to meet any of the requirements specified above. In addition, any or all of the following defects shall be sufficient cause for rejection: 1.Defects that indicate imperfect molding. 2.Defects indicating honeycombed or open textured concrete. 3.Cracked or severely chipped elements. 4.Color variation on front face of panel due to excess form oil or other reasons. All reinforcing steel shall be in accordance with Section 602 and shall be epoxy coated. Precast concrete Mechanically Stabilized Earth wall facing elements shall also conform to MP 604.02.40. 626.5.1.1.2-Modular Block Facings: The length and width of each block shall be within ±1/8 inch. The height of each block shall be within ±1/16 inch. Hollow units shall have a minimum wall thickness of 1.25 inch. When a broken face finish is used the dimension of the front face shall be within one (1) inch of the theoretical dimension of the unit. All units shall be sound and free of cracks or other defects that would interfere with the proper placing of the unit or significantly impair the strength or performance of the construction. Cracks greater than 1/64 inch wide and greater than 25% of the block height is grounds for rejection. The front fact or faces of units that are to be exposed shall be free of chips, cracks or other imperfections that can be seen when viewed from a distance of thirty (30) feet under diffused lighting. Up to 5% of the shipment may contain slight cracks or small chips not larger than one (1) inch. Color and finish shall be shown on the shop drawings and shall be erected with a running bond configuration. When cap units are used they shall be cast to or attached to the top of the modular block wall in strict accordance with the manufacturer’s recommended procedure. 626.5.1.1.2.1-Modular Block Mix Design: Each manufacturing facility shall provide a copy of their mix design, including test results and material sources, to MCS&T Division for each type of block that they manufacture. A separate mix design shall be required for each type of block, as the compaction of each type of block may vary and affect the various test result s. An approved independent laboratory shall perform the testing when establishing the mix design. After initial approval, each mix design shall remain approved for a period of three years after the date of initial approval. If there are any changes in the mix, such as changes in material sources, any materials such as pigments are added, or the pigment color is changed, then a new mix design shall be required. The modular block units shall conform to the following: All of the units shall conform to AS TM C1372, except that:
a.The minimum compressive strength requirements shall be 4000 P si for any individual unit. The average of five units shall be used as the mix design strength.
b.The maximum 24 hour water absorption shall not exceed 7%. The average of five units shall be used as the mix design absorption.
c.The freeze/thaw durability of wall units tested in accordance with ASTM C1262 in a 3% saline solution shall be the minimum of the following:
1.The weight loss of each of five test specimens at the conclusion of 90 cycles shall not exceed 1% of its initial weight.
2.The weight loss of each of 4 of the 5 test specimens at the conclusion of 100 cycles shall not exceed 1.5% of its initial weight, with the maximum allowable weight loss for the 5 th specimen to not exceed 10%.
d.The freeze/thaw durability of cap units shall be tested in accordance with ASTM C1262 in a 3% saline solution shall be the minimum of the following:
1.The weight loss of each of five test specimens at the conclusion of 40 cycles shall not exceed 1% of its initial weight;
2.The weight loss of each of 4 of the 5 test specimens at the conclusion of 50 cycles shall not exceed 1.5% of its initial weight, with the maximum allowable weight loss for the 5th specimen not to exceed 10%.
e.ASTM C1262 test results shall be recorded and reported in 10 cycle intervals. 626.5.1.1.2.2-Modular Block Production: Each manufacturing facility shall provide the Engineer with a copy of their quality control plan and procedures. Sampling and Test ing shall conform to ASTM C140, except: Section 6.2.4 shall be deleted and replaced with the following: "The specimens shall be coupons cut from a face shell of each unit and sawn to remove any face shell projections. The coupon size shall have a height to thickness ratio of 2 to 1 before capping and a length to thickness ratio of 4 to
1.The coupon shall be cut from the unit such that the coupon height dimension is in the same direction as the unit height dimension. Compressive testing of full size units will not be permitted. The compressive strength of the coupon shall be assumed to represent the net area compressive strength of the whole unit." Each manufacturing facility is required to sample and test each block type at the rate of one sample per 5000 units of continuous production from each mix design or fraction thereof (if production is interrupted) as part of their overall quality control testing. Each manufacturing facility shall forward all quality control test reports and documen tation to the MCS&T Division. The manufacturing facility or other testing facilities may perform this quality control testing. The average compressive strength of each lot of the modular block units shall be a minimum of 90% of the mix design strength, a nd the average absorption of each lot shall be between 1.5% less than to 0.5% greater than the mix design absorption. If the compressive strength or absorption criteria are not met, then the modular block in that lot are rejected and cannot be incorporated into the work unless that lot is tested and found to be acceptable under section 626.5.1.1.2.1. Cap units and wall units shall be sampled and tested as separate block types. Minimum manufacturer testing shall include 6 randomly selected units and the following testing:
a.Compressive strength (average of 3 units)
b.24 hour absorption (average of 3 units) The MCS&T Division will randomly select 6 units for testing by the Division for every 15,000 units of continuous production from each mix design or fraction thereof (if production is interrupted). MCS&T may require the manufacturer to conduct freeze/thaw durability testing when inconstancies in the test results arise. 626.5.1.1.2.3-Modular Block Sealing : All modular block retaining wall surfaces shall be sealed. This work shall consist of preparation, furnishing and applying the surface sealer to the exposed front face, of all the wall units, as well as the back side of the upper courses of the wall layer of reinforcement, and the top of the uppermost block or cap unit. Sealers shall be silane and/or siloxane based and specifically formulated for use on porous surfaces such as concrete block. Sealers shall be tested in accordance with ASTM E514 on a block wall, and shall provide a minimum of 90% reduction in leakage. Three dry-cast concrete block specimens shall be treated with the sealer and tested for absorption in accordance with ASTM C140. The sealer shall provide a minimum of 90% reduction in water absorption when tested in this manner. Due to the potentially hazardous ingredients contained in sealer formulations extreme care must be exercised in their handling and use, and the manufacturer’s recommendations shall be closely followed. Construction Requirements:
1.The Contractor shall comply with the manufacturer’s written instructions for preparing, handling and applying the surface sealer.
2.The surface to be treated shall receive a light water -blast to the extent that the surface is clean and free of oils.
3.Before the surface sealer is applied, the surface shall be dry and free of all dust, debris, and frost.
4.Surface sealers shall be applied at the heaviest application rate specified by the manufacturer. All materials and work performed as specified above will be incidental to the construction of the wall. 626.5.1.1.3-Wire Facings: Wire facing shall be shop fabricated of cold drawn steel wire conforming to the minimum requirements of AASHTO M 336 and welded into the finished configuration in accordance with AASHTO M 55. Galvanizing shall conform to the minimum requirements of AASHTO M 111. Retention material shall be placed along the back face of the wire facing to retain the backfill behind the wall. Retention material shall be capable of retaining the backfill, UV resistant and shall have a high permittivity. 626.5.1.1.4-Soil Reinforcing and Attachment Devices: All reinforcing and attachment devices shall be carefully inspected to insure they are true to size and free from defects that may impair their strength and durability. Ensure that pins used t o align the precast components during construction are of the size, shape and material required for the wall system chosen. 626.5.1.1.5-Metal Soil Reinforcing or Attachment Devices: Cutting of reinforcing strips or mesh at vertical obstacles shall not be permitted. C are must be taken to avoid damage to the galvanized coating during handling, storing, and shipping. The following requirements shall apply to all soil reinforcing and attachment devices:
A.Reinforcing strips shall be hot rolled from bars to the required shape and dimensions. Their physical and mechanical properties shall conform to ASTM A36. Galvanization shall be required and shall conform to the minimum requirements of AASHTO M 111.
B.Reinforcing mesh shall be shop fabricated of cold drawn steel wire conforming to the requirements of paragraph one of Section 709.4. Galvanization shall be applied after the mesh is fabricated and shall conform to the minimum requirements of AASHTO M 111.
C.The tie strips shall be shop fabricated of a hot rolled steel conforming to the minimum requirements of ASTM A570, Grade 50 or equivalent. Galvanization shall be required and shall conform to AASHTO M 111.
D.Loop embedments shall be fabricated of cold drawn steel wire conforming to ASTM A510, UNS G10350 or AASHTO M 336. Loop embeds shall be welded in accordance with ASTM A 185. Both shall be galvanized in accordance with ASTM B633 or AASHTO M 111.
E.Bolts shall meet the requirements of AASHTO M 164. Nuts shall meet the requirements of AASHTO M291 Grade DH or AASHTO M 292 2H. Fasteners shall be galvanized in accordance with AASHTO M 232.
F.Connector pins and mat bars shall be fabricated from cold drawn steel conforming to AASHTO M 336 and welded to the soil reinforcement mats as shown in the plans. Galvanization shall be required and shall conform to AASHTO M 111. 626.5.1.1.6-Geosynthetics Soil Reinforcing or Attachment Devices: Cutting of geosynthetic reinforcing longitudinal to the wall face at vertical obstacles shall not be permitted. End to End splicing of geosynthetic material will not be permitted. The geosynthetic used shall meet the minimum requirements shown on the shop drawings. Each roll of geosynthetic material shall be labeled as to its properties. Geosynthetics shall be made of polypropylene, high-density polyethylene or high tenacity polyester fibers having cross-sections sufficient to permit significant mechanical interlock with the soil/backfill. Geosynthetics shall have a high tensile modulus in relation to the soil/backfill. Geosynthetics shall have a high resistance to deformation under sustained long term design loads while in service and resistant to ultraviolet degradation, to damage under normal construction practices and to all forms of biological or chemical degradat ion normally encountered in the material being reinforced. Store the geosynthetics in conditions above 20º F and not greater than 140º F. Prevent mud, wet cement, epoxy, and like materials from coming into contact with and affixing to the geosynthetic material. Rolled geosynthetic may be laid flat or stood on end for storage. Cover the geosynthetic and protect from sunlight prior to placement in the wall system. Carefully inspect all reinforcement to ensure they are the proper size and free from defects that may impair their strength and durability. The geosynthetic reinforcement structure shall be dimensionally stable and able to retain its geometry under construction stresses and shall have high resistance to damage during construction. The contract or shall submit a manufacturer’s certification that the geosynthetics supplied meets the design criteria shown on the shop drawings, measured in full accordance with all test methods and standards specified. In case of dispute over validity of values, the Engineer can require the contractor to supply test data from an approved laboratory to support the certified values submitted. The Contractor’s submittal's package shall include actual test results for tension/creep, durability/aging, construction damage , pullout, quality control and a copy of the Manufacturers installation procedures. Also included should be the Long -Term Design Strength (LTDS) of the Geosynthetic material. The Manufacturer shall also provide written certification that all resin used to produce the geosynthetic is virgin and classified as high density polyethylene, polypropylene, or high tenacity polyester and is capable of withstanding direct exposure to sunlight for 14 days with no measurable deterioration as per ASTM D4355. The allowable tensile strength shall not exceed 30% for class 1 walls and 25% for all other walls of the ultimate tensile strength of the reinforcement used. The allowable tensile properties of geosynthetic reinforcement as shown on the shop drawings shall be calculated using the following method. Property Method Tensile Strength Ultimate, kN/m ASTM D4595 Long-term (Ta), kN/m FHWA/SA-93-025 Where: Ta= Tult/ {(RFcr) (Rfid) (Rfdu)} Tult Ultimate Tensile Strength shall be the minimum average roll value ultimate tensile strength as tested per ASTM D4595. RFcr Partial Factor for Creep Deformation is the ratio of Tult to the creep limited strength determined in accordance with ASTM D5262. The test results shall be extrapolated for a 100 year design life per GRI GG4. Creep performance data of a polymer product at a designed temperature is limited to one order of magnitude in extrapolation. Creep performance data at an elevated temperature permits an additional order of magnitude in extrapolation with time temperature superposition principals. Elevated temperature testing of the specific geogrid for 10,000 hours or creep testing at room temperature for 100,000 hours is required. Creep limited strength testing is required on representative samples of the finished product for each product proposed for use and not a single component of the geogrid (i.e. polymer strand ). Default values for RFcr are not allowed. Rfid Partial Factor for Installation Damage, shall be determined from construction damage tests for each product proposed for use with project specific representative or more severe backfill and construction techniques. The backfill soil used if other than project specific, shall have a D50 > 1” (30 mm) sieve. T esting shall be consistent with GRI GG4. A Maximum Rfid value shall be used if such testing has not been conducted. RECOMMENDED VALUES FOR Rfid Geosynthetic Min. Rfid Max. Rfid HDPE uniaxial geogrid 1.20 1.45 PP biaxial geogrid 1.20 1.45 PVC - coated PET geogrid 1.30 1.85 Acrylic-coated PET geogrid 1.30 2.05 Woven geotextiles (PP and PET) 1.40 2.20 Nonwoven geotextiles (PP and PET) 1.40 2.50 Silt – film woven PP geotextiles 1.60 3.00 Rfdu Partial Factor for Durability / Aging is the combined partial factor for potential chemical and biological degradation. R fdu shall be determined from polymer specific (HDPE and PP as identified by specific gravity and melt flow index and PETP as identified by CEG number and intrinsic viscosity) durability testing covering the range of expected soil environments. Prior to appro val by the Engineer, the manufacturer shall submit test results from a minimum of at least four (4) tests conducted in accordance with EPA 9090 at temperatures of 73° and 122°F. EPA 9090 test results shall include the following minimum number of leachate types: PH Minimum # of test results 3 pH 7 1 7 < pH < 9 1 9 < pH < 11 1 1 pH 14 1 As a minimum, the following tests should be performed for geogrids after immersion in the above-described leachates: TEST MAX % CHANGE TEST PROCEDURE ALLOWED Mass per Unit Area EPA 9090 ±1.0 Dimensions EPA 9090 ±1.0 Thickness ASTM D374C ±5.0 Wide Width Strip Tensile ASTM D374C -2.0 FSd shall not be less than the recommended minimum values discussed in FHWA/RD -89-186 and listed below: High Density Polyethylene (HDPE) 1.10 Coated High Tenacity Polyester (PETP) 1.15 Polypropylene (PP) 1.25 Geotextiles 1.60 Uncoated High Tenacity Polyester (PETP) 1.60
1.Composite (flexible/coated) geogrids shall be evaluated based on the durability characteristics of the interior reinforcement polymer. Therefore, any protective coating shall be removed prior to durability testing unless a minimum 40-micron coating thickness is used on flexible geogrids and certified by the manufacturer.
2.For soils of potential concern, as presented below (modified soils shall include lime stabilized soil, cement stabilized soil or concrete), only polymers listed as “ no effect ” shall be used within or adjacent to (3 feet shortest measurable distance) these soil environments (Ref: Table 28, FHWA/RD-89-186). SOIL ENVIRONMENT PETP PE PP PVC Acid Sulfate Soils ? NE ? ? Organic Soils NE NE NE ? Salt Affected Soils ? NE NE NE Ferroginous NE NE X ? Calcareous X NE NE ? Modified Soils X NE NE ? NE = No Effect ? = Questionable Use X = Not Recommended RECOMMENDED MINIMUM VALUES FOR RFdu Products Aging Reduction factor, Rfdu – 100 years pH ≤ 3 3 < pH ≤ 5 5 < pH < 8 8 < pH < 9 pH > 9 PET Geotextiles Mn < 20,000 40<GEG<50 * 2.0 1.6 2.0 * PET Coated Geogrids Mn > 25,000 GEG<30 * 1.3 1.15 1.3 * Polypropylene and HDPE Geogrids 1.1 1.1 1.1 1.1 1.1 * Use of materials in this pH range is not recommended but can be used if product specific testing is done. 626.5.1.3-Joint Materials: Joint materials are to be installed to the dimensions and thicknesses in accordance with the plans or approved shop drawings, unless otherwise indicated:
A.Provide either preformed EPDM rubber pads conforming to ASTM D2000 for 4AA, 812 rubbers; neoprene elastomeric pads have a Durometer Hardness of 55 ± 5; or polyethylene bearing pads meeting the density requirements of ASTM D1505 in horizontal joints between elements.
B.Cover all joints between elements on the backside of the wall with a geotextile fabric that meets the requirements of Section 715.11.4 of the Specifications. The minimum width and lap of the fabric shall be as follows: Vertical and horizontal joints : 12”; lap -4”. 626.5.1.4-Acceptance: The Contractor shall furnish the Engineer a Certificate of Compliance certifying the above materials comply with the applicable contract specifications. 626.5.2-Concrete Leveling Pad: All concrete used in the leveling pad s hall as a minimum conform to Section 601 of the Specifications for Class C Concrete. 626.5.3-Select Granular Backfill: 626.5.3.1-Test Requirements: A11 backfill material used in the structure volume shall conform to the following gradation limits as determined by AASHTO T-27: Sieve Size Percent Passing 4 inches (100mm) 100 No. 40 (425 µm) 0-60 No. 200 (75 µm) 0–15 Bottom Ash or Fly Ash material will not be considered as select granular backfill unless it is specified in the contract documents. The backfill shall conform to the following additional requirements:
A.The plasticity index (P.I.) as determined by AASHTO T-90 shall not exceed 6, or the material is described as non-plastic.
B.The material shall exhibit an angle of internal friction of not less than 34 degrees (unless otherwise stated in the plans), as determined by the standard Direct Shear Test, utilizing a sample of the material compacted to 95% of AASHTO T-99, Methods C or D (with oversized correction as outlined in Note 7) at optimum moisture content. No angle of internal friction testing is required for backfills where 80% of sizes are greater than ¾ inch.
C.Soundness: The materials shall be substantially free of shale or other soft, poor durability particles. The material shall have a magnesium sulfate soundness loss of less than 30% after Four cycles as determined by AASHTO T-104 or a sodium sulfate loss of less than 15% after five cycles as determined in accordance with AASHTO T-104.
D.Electrochemical R e q u i r e m en t s : The backfill materials shall meet the following criteria: Requirements Test Methods ***Resistivity greater than 3,000 ohm Centimeters AASHTO T-288 **Ph 5-10 AASHTO T-289 *Chlorides less than 100 parts per Million AASHTO T-291 *Sulfates less than 200 parts per million AASHTO T-290 Organic Content: 1% maximum AASHTO T-267 * If resistivity is greater than 5,000 ohm -cm, the chlorides and sulfates requirements may be waived. Requirement is waived if geosynthetics are used for soil reinforcements and attachment devices . ** May be adjusted if geosynthetic material is used for soil reinforcements or attachment devices see shop drawings and section 626.5.1.1.6. *** Requirement is waived if geosynthetics are used for reinforcements and attachment devices.
E.Steel slag as defined in 703.3.1 shall not be used in this item. 626.5.3.2-Quality Control Testing: Quality control of the select granular backfill material for backfill is the responsibility of the Contractor as specified in 106.1. The Contractor shall maintain necessary equipment and qualified personnel to perform all sampling and testing necessary to determine the magnitude of the various properties of the material governed by the Specifications and shall maintain these properties within the limits of the Specifications. The Contractor shall submit a Quality Control Plan detailing the methods by which the Quality Control Program will be conducted. The plan prepared in accordance with the guidelines set forth in the appropriate portions of MP 307.00.50 and MP 717.04.21, shall be submitted to the Engineer at the preconstruction conference. The work shall not begin until the plan is reviewed for conformance with the contract documents. 626.5.3.3-Sampling and Testing: Frequency of sampling and testing shall be in accordance with the Contractor’s Quality Control Plan. The minimum sampling and testing frequencies for gradation and Atterberg limits shall be as indicated in Attachment 1 of MP 307.00.50. The material shall be sampled in accordance with MP 700.00.06. The minimum sampling and testing frequency for compaction will be in accordance with MP 717.04.21. Material failing gradation requirements during placement shall be evaluated immediately and may be subject to r etesting to verify the angle of internal friction at the expense of the contractor. 626.5.3.4-Acceptance: The Contractor shall furnish certified test results that the select granular backfill meets the contract specifications . The test results for the select granular backfill shall not be used to verify compliance for a period exceeding one year. The Division may request that the tests be performed at any time if the material changes. Additional tests for gradations and plastic limits shall be determined during the placement of the material. Acceptance for compaction shall be on a lot -by-lot basis. A lot shall be divided into five approximately equal sized sub-lots. A sub-lot shall consist of the quantity of material to backfill a single lift for 100 feet of wall and at least one test per lift. One nuclear moisture and density measurement shall be made at a random location within each of the five sub - lots; random locations shall be determined in accordance with MP 712.21.26. For material having 40% or more retained on the ¾ inch (75mm) sieve, MP 700.00.24 shall be used to determine the target maximum dry density. For material having less than 40% retained on the ¾ inch (75 mm) sieve, t he target dry density shall be the maximum dry density as determined by the AASHTO T-99 five point laboratory proctor performed on the material in accordance with section 626.5.3.1 (B). The moisture content of the material shall be maintained at a level sufficient to facilitate compaction. For applications where spread footings are used to support a bridge or other structural loads, the target percentage of dry density shall be 100% for other applications the target percentage of dry density shall be 95%. If the results of five density tests on a Lot indicates that at least 80% of the material, in accordance with 106.3.1 (West Virginia AP-A), has been compacted to the specified target percentage of dry density, the Lot will be accepted. If less than 80 % has been compacted to the specified target percentage of dry density and/or the moisture content is outside the tolerance range, no additional material shall be placed until the Lot has been reworked to meet the s pecified requirements. Reworking and retesting shall be at the expense of the Contractor. When the Division performs the testing in the evaluation of reworked Lots, the testing will be at the expense of the Contractor at the unit cost specified in subsection 109.2.2. The backfill material must compact to a stable condition. If the material is not stable under the weight of construction equipment, the contractor must correct the problem or replace the material even if test results indicate that the material meets the moisture and density specifications. The contractor's gradation data shall be evaluated in accordance with applicable sections of Section 307 except that Table 704.6.2 shall not apply. Gradation limits shall be in accordance with Table 703.4. The certification is to include the test results. A revised unit price for calculation purposes will be established based on the delivered quantities and delivered aggregate cost. 626.6-MECHANICALLY STABILIZED EARTH: 626.6.1-Foundation Preparation: The foundation for the structure shall be graded level for a width equal to the length of reinforcement elements plus one (1) foot or as shown in the plans. Prior to wall construction, except where constructed on rock, the foundation shall be compacted with a smooth wheel vibratory roller. Any foundation soils found to be unsuitable shall be removed and replaced with select granular backfill as per Section 614.5.1.4 of the specifications. Construction methods for t he following sh all be per the indicated section of the Specifications: Item Section Unclassified Borrow Excavation 211 Structure Excavation 212 Wet Excavation 212 Rock Excavation 212 Select Material for Backfilling 212 Concrete 601 Reinforcing Steel 602 626.6.2-Wall E rection: A MSE w all supplier representative shall be present a minimum of three (3) days and as required thereafter during erection of the wall to assist the fabricator, contractor, and Engineer. The cost of the representative shall be considered incidental to the unit price of the MSE Wall System. When facing elements are handled by means of lifting devices they shall be lifted by connecting to the upper edge of the element. Facing elements shall be placed so that their final position is vertical or battered as shown in the plans. Facing elements shall be placed in successive horizontal lifts in the sequence shown in the plans as backfill placement proceeds. As backfill material is placed behind the elements, the elements shall be maintained in position by means of temporary wedges or bracing according to the wall supplier's recommendations. The Contractor shall not have more than two levels of temporary wedges in place at any time during wall erection. Concrete facing vertical tolerances and horizontal alignment tolerances shall not exceed ¾ inch. The overall vertical tolerance of the wall (top to bottom) shall not exceed ½ inch per ten ( 10) feet of wall height. Reinforcement elements shall be placed normal to the face of the wall, unless otherwise shown in the plans. Prior to placement of the reinforcing elements, backfill shall be compacted in accordance with these Specifications. 626.6.3-Backfill Placement: Construction methods shall be in accordance with section 212 of the Specifications which requires separation fabric between random material and the select granular backfill material. A minimum non woven geotextile of 6 ounces per square yard shall be place on the back face of the excavation between the granular backfill material and the random excavated material. Backfill placement shall closely follow erection of each course of facing elements. Backfill shall be placed in such a manner as to avoid any damage or disturbance of the wall materials or misalignment of the facing or reinforcing elements. A ny wall materials that become damaged during backfill placement shall be removed and replaced at the Contractors expense. The Contractor at his expense shall correct any misalignment or distortion of the wall facing elements due to placement of backfill outside the limits of this specification. At each reinforcement l evel, the backfill shall be placed to the level of the connection. Backfill placement methods near the facing shall assure that no voids exist directly beneath the reinforcing elements. The backfill required to be placed in front of the wall, from the leveling pad to finished ground, shall be placed immediately after the select granular backfill is above the first layer of soil reinforcing. The maximum lift thick ness after compaction shall not exceed six ( 6) inches unless approved by the Engineer. The Contractor shall decrease this lift thickness, if necessary, to obtain the specified density. The moisture content of the backfill material prior to and during com paction shall be uniformly distributed throughout each layer. Backfill materials shall have placement moisture content less than or equal to the optimum moisture content. Backfill material with a placement moisture content in excess of the optimum moistur e content shall be removed and reworked until the moisture content is uniformly acceptable throughout the entire lift. The moisture content of the select granular material shall be maintained at a level sufficient to facilitate compaction. Compaction within three (3) feet of back face of the wall shall be achieved by at least three passes of a lightweight mechanical tamper, roller, or vibratory system. At the end of each day’s operation, the Contractor shall slope the last level of the backfill away from the wall facing to rapidly direct runoff away from the wall face. In addition, the Contractor shall not allow surface runoff from adjacent areas to enter the wall construction site. One foot behind the modular block units and the modular block uni t cores shall be filled with crushed granular material with less than 2% passing the #200 (75 µm) sieve and shall be consistent with the manufacture recommendation. If the modular block unit cores are not accessible the engineer may upon the advice of the wall designer omit the fill in the modular block cores. 626.7-RETAINING WALL, CAST-IN-PLACE REINFORCED CONCRETE: 626.7.1-General: Except as otherwise shown in the plans or herein, construction methods for cast-in-place retaining walls shall comply with the Specifications. Construction methods for t he following sh all be per the indicated section of the Specifications: Item Section Unclassified Borrow Excavation 211 Structure Excavation 212 Wet Excavation 212 Rock Excavation 212 Select Material for Backfilling 212 Concrete 601 Reinforcing Steel 602 626.7.2-Architectural Forms: 626.7.2.1-General: Construct forms to sizes, shapes, lines, and dimensions shown, and as required to obtain accurate alignment , location, level, and plumb work in finished structures. Provide for openings, offsets, keyways, recesses, chamfers, blocking, screeds, bulkheads, and other items as required. Fabricate forms to prevent cement paste from leaking while placing concrete and for easy removal without hammering or prying against exposed concrete surfaces. Provide crush plates where stripping might damage cast concrete surfaces. Provide top forms for inclined surfaces where slope is too steep to place concrete. Solidly butt joints and provide backup material at joints to prevent leakage and fins. Assemble forms so that they may be easily removed without damaging exposed concrete surfaces Provide temporary form openings where inaccessible formwork interior can be cleaned and inspected before placing concrete. Place temporary form openings as inconspicuously as possible, consistent with project requirements. When drilling forms used for exposed concrete, drill from the contact face to the outside to suit the ties used and to prevent leakage of concrete mortar. Do not splinter the forms by driving ties through improperly prepared holes. Unless otherwise shown in the plans: Provide sharp, clean corners at intersecting planes with no visible edges or offsets; or provide accurately formed chamfered corners using ¾ x ¾ inch strips, surfaced to produce uniformly straight lines and tight edge joints. 626.7.2.2-Form Coatings: Coat form contact surfaces with form-release agent before placing reinforcement . Do not allow excess material to accumulate in forms or to come into contact with reinforcement or surfaces that will be bonded to fresh concrete. Apply coating according to manufacturer’s instructions. Coat steel forms with non-staining, r ust-preventative release agent, or otherwise protect from rusting. Rust-stained steel formwork is not acceptable. 626.7.2.3-Reusing Forms: Split, frayed, delaminated, or otherwise damaged form- facing materials are not acceptable. Clean and apply a new form-release agent to concrete contact surfaces. 626.8-METHOD OF MEASUREMENT: 626.8.1-General: The unit of measurements shall be the area in square feet lying in a plane outside the front face of the structure as determined by the dimensions in the contract documents. The area is taken from the top of the leveling pad to the top of the wall and shall include coping but shall not include barriers, footings, or leveling pads. The area shall be subject to adjustment as provided in Sections 104.2 and 109.2 of t he Specifications. No adjustments of pay quantity shall be allowed for changes in wall design to facilitate the Contractor’s methods of construction of wall type. Unless otherwise specified in the contract documents, items such as concrete barriers that are not part of normal retaining wall construction shall be measured separately for payment. The quantity of earthwork shown in the plans does not include any work within the wall pay limits shown in the plans. Any adjustments to the required amount of embankment or select granular backfill due to the particular wall system proposed by the contractor shall be considered incidental to the project. No separate payment shall be made for increased embankment or increased select granular backfill requirements. The Contractor shall be responsible for any of the cost of changes in waste, borrow, or earthwork quantities from those shown in the plans caused by the requirements of the proposed wall system. 626.8.2-Mechanically Stabilized Earth: The unit price shall include in place: facing elements, soil reinforcing and attachment devices and associated hardware, coping and trim, or similar items that are normal parts of wall construction. No separate payment of these items shall be made. The unit price shall also include, in place, all the following items shown within the wall pay limits in the plans: select granular backfill, fabric for separation, excavation, embankment, foundation preparation, and leveling pads. No separate payment of these items shall be made. 626.8.3-Cast-in-Place Reinforced Concrete: The unit price shall include in place: concrete, reinforcing, joint materials, underdrains, weepholes, or similar items that are normal parts of wall construction. No separate payment of these items shall be made. The unit price shall also include in place: all the following items shown within the wall pay limits in the plans: select material for backfilling, excavation, embankment, fabric for separation, and foundation preparation. No separate payment of these items shall be made. 626.9-BASIS OF PAYMENT: The quantities, determined as provided above, w ill be paid for at the contract price per unit of measurement, respectively, for each pay item listed below and shown in the bid schedule, which prices and payment will be full compensation for the work prescribed in this section.
626.10 Pay Items:
ITEM DESCRIPTION UNIT 626001-* Retaining Wall, Cast-In-Place Reinforced Concrete Square Foot 626002-* MSE Retaining Wall , “vendor name” Square Foot 626003-* MSE Modular Block Retaining Wall , Class “class” Square Foot 626004-* MSE Wire Face Retaining Wall, “vendor name” Square Foot * Sequence number “class” = a number designating class in accordance with the following table: Class Wall Height Allowable substitutions for each class I 40 ft. or less ------ II 20 ft. or less Class I III 10 ft. or less Class I or II IV 5 ft. or less Class I, II, or III See Division Approved Source/Product Listing page for approved vendor list. SECTION 627 THROUGH SECTION 630-BLANK
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Source: Standard Specifications for Roads and Bridges, 2023 Edition. Pages 521–538 of 1,006. View official source ↗