Materials Certification Letter certifying that the applicable m aterials comply with this section of the specifications. Materials shall meet the following additional requirements:
673.031 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
712.061 Structural Precast Concrete with the following exceptio ns:
Materials. Materials are modified as follows:
The maximum water cement ratio shall be 0.42, use of calcium ni trite is not required, and the minimum 28 day compressive strength shall be 4600 psi.
The third paragraph 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 concrete 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 ach ieve a consistent shade of gray or other color as determined by the Resident.
Concrete Testing. Concrete testing requirements are modified a s follows:
Replace the paragraph which begins “A minimum of 8 ….” With the following: The Contractor shall make and test at least one set of cylinders for every 50 yd3 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 for every 200 yd 3. Tolerances. Maximum dimensional deviation of formed unit dime nsions shall not vary more than 1/2-inch or 2 percent or the manufacturer’s published tolerances, whichever is less. Units not meeting the specified tolerances will be rejec ted.
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. E.
manufactured with a high degree of quality control. The Manufa cturer is responsible for establishing and maintaining a quality control program to ensure compliance with the requirements of the specification. The pur pose of the QC testing program is to verify that the reinforcement geosyntheti c being supplied to the project is representative of the material used for performa nce testing and approval. Conformance testing shall be performed as part of th e manufacturing process and may vary for each type of product. As a minimum th e 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 h aving legal authority to bond the manufacturer. In case of dispute over validity of values, the Resident can require the Contractor to supply test data f rom an agency approved laborato ry 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. Leveling pad shall have a minimum thickness of 4 inches. Unless otherwise specified, c oncrete for leveling pads shall be accepted under Method “C” requirements.
4 Drainage Stone Fill Concrete wall unit voids shall be filled with material
that conforms to the requireme nts of Standard Specification Crushed Stone, ¾ -Inch, meeting the requirements of Section 703.13 . Compaction of the stone fill will be required before the block surfaces are cleaned to ensure good interface connection strength between geogrids and blocks .
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.
673.04Design Requirements The wall shall be designed with a s ervice life of not less
than 75 years. The Wet Cast Small Landscape Block Wall shall b e designed and sealed by a Professional Engineer licensed in the State of Maine. The wall shall be designed in accordance with the following:
as LRFD
and FHWA-NHI-10-025, Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, Volumes I and II, current edition.
Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, current edition
Where conflicting requirements occur, the more stringent requir ements shall govern. 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 p lane 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 com pliance with LRFD
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. Overt urning and sliding provisions of LR FD 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 load factors shall be as specified in LRFD Section 11. Resistance factors f or internal design are specified in LRFD Section 11. Maximum reinforcement loads shal l be calculated using the Simplified Method approach. Calculations for factore d stresses and resistances shall be based upon assumed conditions at the end o f the design life.
reinforcement design strength (T al) shall be determined by reducing T ult by reduction factors (RF) in accordance with the documents referen ced above. The
designer shall procure and use the manufacturers tested and cer tified geosynthetic 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 factors, a combined default reduction f actor RF = 7 shall be used in accordance with the referenced documents. For RF ID, the installation damage reduction factor shall be checked in accordance with LRF D and FHWA- NHI-09-087.
connection strength between the geosynthetic reinforcement and the concrete blocks shall be checked in accordance with LRFD and FHWA-NHI-10 -024 and FHWA-NHI-10-025, Volumes 1 and 2.
correction factor (α) used in pullout design, shall be determined from project specific pullout tests using t he proposed geosynthetic in the s pecified project backfill material or equivalent soil. The pullout resistance fa ctors shall be determined in accordance with LRFD and FHWA-NHI-10-024 and FHWA -NHI- 10-025, Volumes 1 and 2. In the absence of test data, empirica l relationships may be used to determine the pullout resistance factors, any empiri cal relationships used in design shall be referenced in the design calculations.
the reinforced fill zone for internal stability design shall be assumed have a friction angle of 34 degrees unless specific project select backfill is tested for frictional strength. The friction angle of the foundation soils and rand om backfill shall be assumed to be 30 degrees unless otherwise shown on the plans.
bottom to the top of each wall section. The reinforcement leng th defining the width of the entire reinforced soil mass may vary with wall height. The minimum length of the soil reinforcement shall be 5 ft, but shall not be less tha n 70 percent of the wall height, H, for walls with level surcharges, or 70 percent of H1 for walls with a sloped surcharge. Reinforcement length will be determined by the geote chnical wall designer. The mechanical wall height, H or H1, shall be the ve rtical difference between the top of the leveli ng footing and the elevation at wh ich the failure surface, as described above, intercepts the ground surface supported by the wall.
Landscape Block Wall shall be clearly indicated on the Shop Dra wings. Walls shall be dimensioned so that the factored bearing resistance of the f oundation soils, as noted on the Plans, is not exceeded.
accordance with LRFD, and shall include an evaluation of the ma ximum vertical spacing between reinforcement layers.