Resident a Materials Certification Letter certifying that the a pplicable materials comply with this section of the specifications. Materials shall meet the f ollowing additional requirements:
681.031 Concrete Units The Materials Certification Letter desc ribed above shall contain
the date of concrete casting, a lot identification number, comp ressive strength results, and entrained air results. All prefabricated concrete units shall c onform to the requirements of Materials Materials are modified as follows: the maximum water cement ratio shall be 0.42, use of calcium nitrite is not required unless the desi gn of the concrete wall units requires fabrication with reinforcing steel, the minimum 28-day compressive strength shall be 4600 psi. Paragraph three of Materials is not applicable to this Section .
Quality Control and Quality Assurance. Quality Control and Qua lity Assurance is modified as follows: delete the paragraph which begins with “Th e contractor shall provide a private office…” Curing. Curing requirements are modified as follows:
Replace the first sentence in the paragraph which begins “Forms shall remain …” with the following: The forms shall remain in place until the c oncrete has gained sufficient strength such that removal of the forms and subseque nt handling will not damage the units. Add the following paragraph at the end of the Curing section: Face texture of the units shall be a formed finish on all exposed surfaces. Pigment shall be added during the casting process of the concrete unit to achieve a co nsistent shade of gray or other color as determined by the Resident.
Concrete Testing. The concrete testing requirements are modif ied as follows:
Replace the paragraph which begins “The Contractor shall cast a minimum of 8 ….” With the following: The Contractor shall make and test at least one set of cylinders for every 50 CY of production concrete used to cast the concrete units. Replace the paragraph which begi ns “At least once …” with the f ollowing: The Contractor shall make four cylinders for use by the Departm ent to represent every 200 CY or fraction thereof.
Tolerances Maximum dimensional deviation of formed unit dimensions shall not vary more than ½-inch or 2 percent of the unit dimension or the manu facturer’s published tolerances, whichever is less. Units not meeting the specified tolerances will be rejected.
2 Geosynthetic Reinforcement Geosynthetic Reinforcement shall be as required
by the proprietary wall system m anufacturer or wall designer. Geosynthetic reinforcement shall consist of a geotextile or geogrid approved by the Geotec hnical Engineer. Substitution of a geosynthetic other than that required by the proprietary w all system manufacturer shall not be allowed unless approved by the Geotechnical Engineer after submittal of shop drawings and pullout and interface friction test data.
long chain polymeric filaments or yarns formed into a stable ne twork such that the filaments or yarns retain their position relative to each other during handling, placement, and design life. At least 95 percent by weight of t he long chain polymer shall be polyolefin or polyester. T he material shall be free o f defects and tears. Geotextiles used for reinforcement shall conform as a minimum t o the properties indicated for 722.01, Stabilization/Reinforcement Geotextile an d shall meet the requirements of part D and E below. Geotextiles shall have a m inimum permeability greater or equal to that shown on the Shop Drawings and the rei nforced soil permeability.
tensile elements with aperture geometry sufficient to permit si gnificant mechanical interlock with the surrounding soil or rock. The geogrid struc ture shall be dimensionally stable and able to retain its geometry under manu facture, transport and installation. Geogrids shall conform as a minimum to the crite ria specified in part D and E below.
shall the have the ultimate tensile strength (T ult) shown on the approved Shop Drawings for the geosynthetics pecified and for the fill types hown. T ult shall be determined from wide width tests specified in ASTM D 4595 for g eotextiles and ASTM D 6637 or GRI:GG1 for geogrids. The ultimate tensile stre ngth value is based on the minimum average roll values (MARV) for the product.
D-4355.
1248.
2, per ASTM D-5261.
RF = 7 may be used in design, provi ded the criteria of 2 throug h 6 are satisfied and 1 is adjusted to 70 percent after 500 hours is satisfied.
manufactured with a high degree of quality control. The Manufa cturer is responsible for establishing and maintaining a quality control program to e nsure compliance with the requirements of the specification. The purpose of the QC t esting program is to verify that the reinforcement geosynthetic being supplied to th e project is representative of the material used for performance testing and approval. Conformance testing shall be performed as part of the manufactu ring process and may vary for each type of product. As a minimum the following index tests shall be considered as applicable for an acceptable QA/QC program: P r o p e r t y T e s t P r o c e d u r e
accordance with ASTM D-4354. Conformance testing procedures are established above. Geosynthetic product acceptance shall be based on ASTM D-4759. The quality control certificate shall include:
geosynthetics supplied meet the respective index criteria set w hen the geosynthetic was approved, measured in full accordance with all test methods and standards specified, or referenced, in this specification.
The manufacturer’s certificate shall state that the furnished g eosynthetic meets the requirements of these specifications as evaluated by the manufa cturer’s quality control program. The values submitted shall be certified by a person having legal authority to bond the manufacturer . In case of dispute over va lidity of values, the Resident can require the Contr actor to supply test data from an agency approved laboratory to support the values submitted, at the Contractor’s cost.
3 Concrete Leveling Pad Concrete for leveling pads shal l be Fill Concrete
conforming to the requirements of Section 502 Structural Concre te. Unless otherwise specified, concrete for leveling pads shall be accepted under M ethod “C” requirements.
4 Drainage Stone Fill Concrete wall unit voids shall be filled with drainage
stone material that conforms to the requirements of 703.13, Cru shed Stone, ¾ -Inch.
5 Backfill Material Backfill material placed behind the concrete wall units shall
meet the requirements of Section 703.20 Gravel Borrow, except t hat the backfill material shall only contain particles that will pass the 3-inch square m esh sieve. The contractor is required to submit a grain size distribution curve (ASTM D 422) and a moisture-density relationship curve (AASHTO T-180) for acceptance of the propose d backfill material and determination of the appropriate installation damage reduction factor (RF ID). Walls with reinforced backfill also require that the backfill m aterial be subjected to pH testing to determine the appropriate durability reduction facto r (RF D). Backfill materials shall meet the criteria in the following table:
Base Polymer Property Criteria Test Method Polyester (PET) pH 3< pH < 9 AASHTO T-289 Polyolefin (PP & HDPE) pH pH > 3 AASHTO T-289
6 Materials Certificate Letter The Contractor, or the s upplier as their agent,
shall furnish the Resident a Materials Certificate Letter for t he above materials, including the backfill material, in accordance with Section 700 of the St andard Specifications. A copy of all test results performed by the Contractor or their supplier necessary to assure contract compliance shall also be furnished to the Resident. The Reside nt will base acceptance upon the materials Certificate Letter, accompanying test reports, an d visual inspection.
681.04Design Requirements The wall shall be designed with a s ervice life of not less
than 75 years. The Precast Aggregate-filled Concrete Block Gra vity Wall shall be designed and sealed by a Professional Engineer licensed in the State of Maine. The wall shall be designed in accordance with the following:
LRFD
Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, Volumes I and II, current edition.
Stabilized Earth Walls and Reinforced Soil Slopes, current edition.
Forty-five days prior to beginni ng construction of the wall, th e design computations shall be submitted to the Resident for review by the Geotechnical Engineer. Any additional design or costs arising as a result of rejection of a wall desi gn by the Geotechnical Engineer shall be borne by the Contractor. Design calculations that consist of computer program generated output shall be supplemented with at least one hand calculation and graphic dem onstrating the design methodology used. Design calculations shall provide thorough d ocumentation of the sources of equations used and material properties. The design b y the wall system supplier shall consider the stability of the wall as outlined below and in the Contract Documents:
determined in accordance with LRFD Article 11 and be analyzeds o that the soil stabilizing components extend sufficiently beyond the failure plane within the reinforced soil mass to stabilize the material.
those applied through traffic loadings, impact on traffic barrier posts, slope surcharge, hydrostatic, and seismic loads shall be accounted for in the de sign. Traffic surcharge and traffic impact loads shall be calculated and applied in complia nce with LRFD Section 11.
consistent with LRFD. Application of load factors shall be tak en as specified in LRFD Section 11. Sliding resistance factors and bearing resistance factors shall be consistent with LRFD. Overturning and sliding provisions of LRFD shall apply.
reinforcement/block connection pullout or rupture shall be cons istent with LRFD Section 11, and checked at each level. Loads, load combinations and lo ad factors shall be as specified in LRFD Section 11. Resistance factors for internal design are specified in LRFD Section 11. Maximum reinforcement loads shall be calculated us ing the Simplified Method approach. Calculations for factored stresses and resistancess hall be based upon assumed conditions at the end of the design life.
reinforcement design strength (T al) shall be determined by reducing T ult by reduction factors (RF) in accordance with the documents referenced above. The designer shall procure and use the manufacturers tested and certified geosynth etic reinforcement reduction factors for creep (RF CR), durability (RF D), and installation damage (RF ID) to determine T al. In absence of manufacturers tested and certified reduction f actors, a combined default reduction factor RF = 7 shall be used in accor dance with the referenced documents. For RF ID, the installation damage reduction factor shall be checked in accordance with LRFD and FHWA-NHI—09-087.
connection strength between the geosynthetic reinforcement and the concrete blocks