242SECTION 236—WOOD PRODUCTS
236.01 Description
These specifications cover the uses and requirements for structural timber and lumber, miscellaneous wood products, and preservative treatments for such wood products where specified.
236.02 Detail Requirements
a.Structural timber and lumber shall conform to AASHTO M168. The species and grade of structural lumber shall be as shown on the plans. The Engineer may approve the substitution of another species of equal or greater strength selected from the “Allowable Unit Stresses for Struc - tural Lumber—Visually Graded” of AASHTO’ s Standard Specifications for Highway Bridges or the supplement to National Design Specification for Stress-Grade Lumber and Its Fastenings of the National Forest Products Association. Except as otherwise specified, the species and grade of structural lumber, timber, and posts for the following applications shall be as follows:
1.Bridges shall be at least 1,550 Fb and: • 5 inch by 5 inch and larger: Southern Pine, No. 1 Dense. • 2 inch through 4 inch by 2 inch through 4 inch: Southern Pine, No. 2 Dense. • 2 inch through 4 inch by 5 inch and through 6 inch: Southern Pine, No. 1. • 2 inch through 4 inch by 8 inch only: Southern Pine, No. 1 Dense. • 2 inch through 4 inch by 10 inch only: Southern Pine, Non-Dense Select Structural. • 2 inch through 4 inch by 12 inch only: Southern Pine, Non-Dense Select Structural.
2.Signs shall be at least 1,100 Fb with material being dressed on all sides and: • 4 inches and less in the least dimension: Southern Pine, No. 2 Non-Dense. • Over 4 inches in the least dimension: Southern Pine, No. 1.
3.Guardrail shall be at least 1,250 Fb Southern Pine, No. 1 Dense.
4.Fence shall be Southern Pine, No. 2, for line, corner, and brace units.
5.Signalization and electrical service shall conform to ANSI Class 5.1. Sawn material, both rough and dressed, shall be certified by the mill as to grade and shall be grade marked in ac - cordance with the grading rules and basic provisions of the American Lumber Standards (PS- 20-70) by a lumber grading or inspection bureau or agency approved by the Department. The grade mark shall be applied after dressing if the sawn material is dressed.
b.Timber piles shall conform to ASTM D25. Piles shall be clean peeled and have a butt circum- ference of at least 31 inches. The Engineer will accept piles for fender systems or other non–load 236.01 243bearing uses under the following criteria provided the piles can be properly driven: A straight line from the center of the butt to the center of the tip may lie partly outside the body of the pile, but the distance between the line and pile shall be not more than 1/2 percent of the length of the pile or 3 inches, whichever is smaller. Points for timber piles shall be steel or cast iron and of a shape that will allow a secure connection to the pile and withstand driving. Timber piles shall be branded prior to shipment with the supplier brand, year of treatment, species of timber and preservative treatment, retentions, class, and length. Brand symbols shall conform to AWPA M6.
c.Timber preservatives shall be used according to their suitability for the condition of exposure to which the timber will be subjected and shall not be used interchangeably. Treatments shall conform to the following limitations:
1.Waterborne preservatives shall be used for timber where a clean surface is desirable. The moisture content of wood material shall be not more than 19 percent at the time of treatment.
2.Pentachlorophenol and creosote may be used for timber that is not to be painted. Timbers treated with pentachlorophenol or creosote shall be free of excess preservative on the wood surface.
3.Preservatives shall conform to the requirements of the American Wood-Preservers Association (AWPA).
4.Pressure treatment shall conform to the AWPA “Use Category System” as follows: • Lumber and timber for bridge structures including bridge decking, guardrail posts, and offset blocks shall be treated to conform to UC4B. • Foundation piles shall be treated to conform to UC4C. • Wood composites shall be treated to conform to UC4A. • Sign posts, fence posts, and gates shall be treated to conform to UC4A. • All other sawn products and round posts less than 16 feet in length shall be treated to conform to UC4A.
5.Marine applications where wood structures or products will be placed in or above salt water, brackish water, or tidal water shall be treated to conform to UC5B.
6.Wood used for highway construction, bicycle trails, pedestrian overlooks and maintenance applications for sign posts, fence posts, wood posts, guardrail posts, bridge decking, gates, stair treads, and offset blocks shall be treated with a chromated copper arsenate (CCA) preservative. Wood used for highway construction, bicycle trails, pedestrian overlooks and maintenance applications for piles, timbers, and composites shall be treated with a CCA, pentachlorophenol, or creosote preservative.236.02 244 7. Wood used for hand-contact surfaces such as handrails, playground equipment, and picnic tables shall be treated with either ammoniacal copper quaternary (ACQ) salt or copper azole (CA) preservative. ACQ and CA wood treatments are highly corrosive to metal. Fasteners or connectors that will be in contact with wood using ACQ or CA wood preservative treatments shall be either 304 or 316 stainless steel or hot-dipped galvanized steel that conforms to ASTM A153 or ASTM A653, Class G185. The Engineer will not permit the use of mechanically galvanized steel hardware or fasteners with ACQ and CA wood treated wood. SECTION 237—STRUCTURE BEDDING MATERIAL AND BEARING P ADS
237.01 Description
These specifications cover material used under bearing devices of structures.
237.02 Detail Requirements
a.Elastomeric Bearing Pads: The elastomer portion of pads shall be new neoprene compound. Pads shall be cast under heat and pressure and may be individually molded or cut from pressure-cast stock. Variations from the dimensions shown on the plans shall be not more than the following: thickness, ±1/16 inch; width, –1/8 to +1/4 inch; length, –1/8 to +1/4 inch. Tolerances, dimensions, finish and appearance, flash, and rubber-to-metal bonding shall conform to A 4-F3-T.063-B2, Grade 2, Method B, in accordance with the RMA Rubber Handbook. Pads shall be furnished in one piece and shall not be laminated unless otherwise specified. Pads shall be furnished in identifiable pack - ages. Adhesive for use with elastomer pads shall be an epoxy-resin compound, compatible with the elastomer, having sufficient shear strength to prevent slippage between pads and adjacent bearing surfaces. Laminated pads shall consist of alternate laminations of elastomer and hot-rolled steel sheets molded together as a unit. The bond between the elastomer and metal shall be such that failure shall occur in the elastomer and not between the elastomer and steel when tested for separation. Material having a nominal durometer hardness of 70 and 50 shall be used for nonlaminated pads and laminated pads, respectively. Test samples shall be prepared from finished pads. Samples of each thickness will be taken from 2 full-size pads from each shipment of 300 pads or less, with 1 additional pad for each additional increment of 300 pads or fraction thereof. Samples shall comply with the following physical requirements when tested in accordance with the ASTM methods designated.
1.Original physical properties: Test results for tear resistance, tensile strength, and ultimate elongation shall be not more than 10 percent below the following specified value:236.02
Source: Virginia Road and Bridge Specifications, 2020 Edition. Pages 270–271 of 1,065.