822Rockfall Mesh

Rockfall Mesh

822.1Wire Mesh

1 Provide rockfall mesh, consisting of 8 x 10 double twist hexagonal netting, zinc and PVC coated in accordance with ASTM A975. Ensure the minimum mesh wire diameter is 0.106 in [2.7 mm] with a maximum tensile strength of 70 ksi [483 MPa] per ASTM A641 for soft temper steel. Ensure mesh characteristics and minimum strength requirements meet the requirements of Tables 1 and 2 in ASTM A 975 for PVC and metallic coated gabion materials.

2 Provide rockfall mesh that is hexagonal, non-raveling, woven, double-twist, hot-dipped, zinc-coated galvanized wire, with the size of the mesh opening being 3¼ in × 4½ in [83 mm × 114 mm], nominal. Match the color of the rockfall mesh shown in the contract and as approved by the engineer.

3 Selvedge or bind perimeter edges of wire mesh to prevent unraveling of the mesh. Use wire with a minimum strength at least equal to the mesh for the selvedge and with a diameter greater than that of the mesh wire and as recommended by the manufacturer.

4 Ensure rockfall mesh meets the requirements listed in Table 822.1-1, Rockfall Mesh Properties.

Table 822.1-1 Rockfall Mesh Properties Property Test Method Nominal Value Tensile Strength ASTM A 975 60 ksi [414 MPa] Galvanized Wire Diameter ASTM A 975 0.120 in [3.05 mm] Zinc Coating ASTM A 975 0.85 oz/ft2 [260 g/m2], min. Galvanized Wire Diameter (For PVC Coated Wire) ASTM A 975 0.106 in [2.7 mm] Zinc Coating (For PVC Coated Wire) ASTM A 975 0.80 oz/ft2 [243 g/m2], min. PVC Coating Thickness ASTM A 975 0.02 in [0.56 mm]

822.2Lacing and Fasteners

1 Provide and use fasteners for connecting edges and ends of mesh rolls at overlaps in accordance with the requirements of ASTM A 975. Supply lacing wires, fasteners, ties, clips, and connecting wire in sufficient quantity for securely fastening all edges of the rockfall mesh as shown in the contract. Ensure all furnished materials are in accordance with ASTM A975 for PVC and metallic coated gabion materials. Provide and use locking

Rockfall Mesh SECTION 822

fasteners for connecting edges and ends of wire mesh at overlaps in accordance with ATM A975. Ensure wire used for fasteners is galvanized with a minimum diameter of

00.118 in [ 3.0 mm]. If lacing wire is used in place of locking fasteners, ensure wire is

0.087 inches [2.2 mm] in diameter prior to galvanizing

2 Ensure lacing and fasteners meet the requirements listed in Table 822.2-1, Lacing Wire and Fasteners.

Table 822.2-1 Lacing Wire and Fasteners Property Test Method Nominal Value Galvanized Wire Diameter (for Lacing Wire) ASTM A 975 0.087 in [2.2 mm] Galvanized Wire Diameter (for Fasteners) ASTM A 975 0.118 in [3.0 mm] PVC Coating Thickness ASTM A 975 0.02 in [0.56 mm]

822.3Anchors

1 For driven and grouted anchors, provide 1 in [25 mm] diameter × 5 ft [1.5 m] long, grade 75 ksi [517 MPa] thread bars in accordance with ASTM A 615 [ASTM A 615M]; epoxy coat, under shop conditions, in accordance with AASHTO M 284 (ASTM A 775) [AASHTO M 284M (ASTM A 775M)] with a minimum coating thickness of 12 mils [0.31 mm] for corrosion protection. Furnish appropriate end hardware for each bar. Coupling of bars will not be permitted unless otherwise approved by the Geology Program.

2 Ensure bearing plates conform to ASTM A36 and are epoxy-coated in accordance with ASTM A775 with a minimum coating thickness of 12 mils [0.31 mm].

3 Ensure all nuts and couplers are heavy duty conforming to the requirements of ASTM A47 or F436, and are appropriately sized for the threaded bar specified. Washers may be flat, beveled, or spherical seat as required to adequately seat and load the anchor system without bending the bar; place washers between the plate and nut. Ensure washers are epoxy-coated for corrosion protection.

4 Provide centralizers fabricated from plastic, steel, or material which is not detrimental to the threaded bar or wire rope anchor. Use the centralizer to support the anchor in the drill hole, position the anchor so at least 0.5 in [ 12.7 mm] of grout cover is provided, and allow grout to freely flow around the anchor and up the drill hole.

822.4Grout

1 Use nonshrink neat-cement or and-cement grout, consisting of a pumpable mixture of type I, II, I/II, or III Portland cement conforming to ASTM C150 and water. Ensure cement

Rockfall Mesh SECTION 822

is fresh and does not contain lumps or other indications of hydration. If sand- cement grout mixes are proposed for use, submit a mix design showing the batch proportions to the engineer for approval. Do not use chloride- containing grouts. Ensure the grout is capable of reaching cube strength of 2500 psi [17.2 MPa] in three days and 5000 psi [34.5 MPa] in 28 days when tested per ASTM C1107. Ensure the anchor grout has a water cement ration of 0.40 to 0.60, and is free of lumps and undispersed cement. Do not use resin grouts.

822.5Top Support Wire Rope

1 Provide wire rope, 0.625 inch [15.9 mm] in diameter with a minimum breaking strength of 41,200 lbs [18,688 kg], constructed of (6 x 9) galvanized steel wire strand conforming to the requirements of ASTM A1023 for the following applications:

822.6Hardware

1 Provide wire rope clips compatible with the wire rope sizes provided. Furnish clips with bases made of drop forged carbon steel and nuts of the heavy -duty hexagonal type. Ensure all components are galvanized in accordance with ASTM A153.

2 Ensure all bolts, nuts, washers, and miscellaneous hardware, such as thimbles, are hot dipped galvanized in accordance with ASTM A153. Grind smooth all welds and rough surfaces prior to galvanizing.