GEOSYNTHETIC WALL REINFORCEMENT

PART 1: GENERAL

1.01	Description

Work includes furnishing and installing geosynthetic reinforcement to the lines and grades designated on the plans.

1.02 Related Work

A. Section  - Segmental Retaining Wall Units

B. Section – Earthwork

C. Section - Drainage Aggregate

1.03 Reference Standards

A. ASTM D 4595 - Tensile Properties of Geotextiles by the Wide-Width Strip Method

B. ASTM D 4632 - Tensile Properties of Geotextiles

C. ASTM D 52 - Tensile Creep Testing of Geosynthetics

D. GRI:GGl - Single Rib Geogrid Tensile Strength

E. NCMA SRWU-1- Determination of Connection Strength between Geosynthetics and Segmental Concrete Units

F. NCMA - Design Manual for Segmental Retaining Walls

G. Where specifications and reference documents conflict, the Architect/Engineer shall make the final determination of applicable document.

1.04 Certification

A. Contractor shall submit a notarized manufacturer's certification, prior to start of work, stating that the geosynthetic reinforcement meets the requirements of this specification.

1.05 Delivery, Storage and Handling

A. Contractor shall check the geosynthetic reinforcement upon delivery to assure that the proper grade and type of material has been received. A product certification should be provided with each shipment.

B. The geosynthetic reinforcement shall be stored above -20°F.

C. Rolled geosynthetic material shall be stored in accordance with manufacturer's recommendations.

1.06 Measurement and Payment

A. Measurement of the geosynthetic reinforcement is on a square yard basis.

B. Payment shall cover geosynthetic reinforcement supply and installation.

C. Quantity of geosynthetic reinforcement as shown on drawings may be increased or decreased at the direction of the Architect/ Engineer based on construction procedures and actual site conditions.

D. The accepted quantities of geosynthetic reinforcement will be paid for per square yard of net quantities shown on the construction drawings. Waste and overlaps are incidental. Payment will be made under:

Pay Item                                                   Pay Unit

Geosynthetic Reinforcement                       SQ. YD.

PART 2: MATERIALS

2.01 Definitions

A. Geosynthetic reinforcement shall be a polymer product specifically manufactured as a soil reinforcement element that meets the requirements of this specification.

B. Concrete segmental retaining wall (SRW) units are as detailed on the drawings and specified under Section – Segmental Retaining Wall Units.

C. SRW Unit pins are as detailed on the drawings and specified under Section SRW Units.

D. Leveling pad material is sand or gravel as specified under Section - SRW Units or low-strength unreinforced concrete.

E. Reinforced backfill (infill soil) is the soil used within reinforced soil mass.

F. Retained backfill or common backfill is the soil behind the reinforced soil mass and leveling pad.

2.02 Geosynthetic Reinforcement Properties

A. The geosynthetic reinforcement shall possess the following minimum design properties, determined by product specific testing as deffined in the NCMA Design Manual for Segmental Retaining Walls (Section 3.5).
                                                            LTDS            Ci             Cds
Geogrid Type "A"                              (1000 lb/ft)       (0.7 )          (0.7)

Geogrid Type "B"                                           (if required)

PART 3: EXECUTION

3.01 Foundation Soil Preparation

A. Foundation soil preparation shall be as specified in Section -SRW Units.

3.02 Wall Erection

A. Wall erection shall be as specified in Section SRW Units.

3.03 Geosynthetic Reinforcement Installation

A. The geosynthetic reinforcement shall be installed at the wall height, horizontal location, and to the extent as shown the project construction plans, or as directed by the Architect/ Engineer.

B. The geosynthetic reinforcement shall be laid horizontally on compacted reinforced backfill and connected to the concrete SRW units. Embedment detail shall be consistent with the SRW manufacturer's recommendations.

C. Correct orientation (roll direction) of the geosynthetic reinforcement shall be verified by the Contractor.

D. Place segmental unit and fill in accordance with Section - SRW Units.

E. The geosynthetic reinforcement shall be pulled taut and free of wrinkles prior to placement of soil fill. The geosynthetic may be secured in place with staples, pins, sandbags, or fill as required by fill properties, fill placement procedures, or weather conditions, or as directed by the Architect/ Engineer.

F. For constructability considerations, maximum spacing between geogrid layers shall be 2.0 vertical feet.