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 t heoretical 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 theys hall 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 results. 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:
individual unit. The average of five units shall be used as the mix design strength.
five units shall be used as the mix design absorption.
ASTM C1262 in a 3% saline solution shall be the minimum of the following:
506 1. The weight loss of each of five test specimens at the conclusion of 90 cycles shall not exceed 1% of its initial weight.
cycles shall not exceed 1.5% of its initial weight, with the maximum allowable weight loss for the 5th specimen to not exceed 10%.
ASTM C1262 in a 3% saline solution shall be the minimum of the following:
cycles shall not exceed 1% of its initial weight;
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%.
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 Testing 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
is in the same direction as the unit height dimension. Compressive testing of full siz e 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 incorporate d 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:
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
507 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 C14 0. 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:
preparing, handling and applying the surface sealer.
surface is clean and free of oils.
debris, and frost.
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 permitt ivity.
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. Care must be taken to avoid damage to the galvanized coating during handling, storing, and shipping.
508 The following requirements shall apply to all soil reinforcing and attachment devices:
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.
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.
minimum requirements of ASTM A570, Grade 50 or equivalent. Galvanization shall be required and shall conform to AASHTO M 111.
ASTM A510 , UNS G1035 0 or AASH TO 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.
requirements of AASH TO M291 Grade DH or AASHTO M 292 2H. Fasteners shall be galvanized in accordance with AASHTO M 232.
conforming to AA SHTO M 336 and welded to the soil reinforcement mats as shown in the plans. Galvanization shall be required and shall conform to AASH TO 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 degradation 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 ma terial. 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
509 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/ {(RF cr) (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 magni tude 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 back fill and construction techniques. The back fill 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.
510 RECOMMENDED VALUES FOR Rfid 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.