Geosynthetic Min. R fid Max. R fid 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 TEST PROCEDURE MAX % CHANGE 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
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.
511 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 ENVIRONM ENT PETP PE PP PVC Acid Sulfate Soils ? NE ? ? Organ ic Soils NE NE NE ? Salt Affected Soils ? NE NE NE Ferroginous NE NE X ? Calcareous X NE NE ? Mod ified Soils X NE NE ?
NE = No Effect ? = Questionable Use X = Not Recommended
RECOMMENDED MINIMUM VALUES FOR RFdu Products Aging Reductio n factor , Rfdu – 100 years pH ≤ 3 3 < pH ≤ 5 5 < pH < 8 8 < pH < 9 pH > 9 PET G eotextiles 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:
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.
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 shall as a minimum conform to Section 601 of the Specifications for Class C Concrete.
512 626.5.3-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 back fill shall conform to the following additional requirements:
or the material is described as non-plastic.
(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.
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 AASH TO T-104.
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 reinforcemen ts 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.
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
513 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-Acce ptance: The Contractor shall furnish certified test results that the select granular backfill meets the contract specifications . The test results for the select granular back fill 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 placem ent 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 specified requirements. Reworking and retesting shall be at the expense of the Contractor. When the Division performs the testing in the evaluation of r eworked Lots, the testing will be at the expense of the Contractor at the unit cost specified in subsection 109.2.2. The back fill 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.
514 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 wi dth 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 back fill as per Section 614.5.1.4 of the specifications. Construction methods for the 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 Back filling 212 Concrete 601 Reinforcing Steel 602
626.6.2-Wall Erection: 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 back fill 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 th e random excavated material.
515 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 back fill 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 level, the back fill 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 thickness 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 wit hin 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 the 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
516 626.7.2-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 back up material at joints to prevent leakage and fins. Asse mble 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, rust-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 back fill 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
517 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 Eart h: 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, will 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.
626.10PAY 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.