580MEMBRANE WATERPROOFING FOR RAILWAY STRUCTURES

Art. 580.01 Membrane Waterproofing for Railway Structures 504

MISCELLANEOUS

580.01Description. This work shall consist of furnishing, transporting and

placing all materials required to construct a membrane waterproofing system on railway structures.

The membrane waterproofing shall be of the bituminous or butyl rubber type as specified on the plans.

580.02Materials. Materials shall be according to the following

Item Article/Section

Note 1. The bitumen used shall be asphalt. The bitumen for mopping and for the protective cover shall be the same type as that with which the fabric is treated.

CONSTRUCTION REQUIREMENTS

580.03General. Surfaces to be waterproofed shall be smooth and free from

projections which might damage the waterproofing membrane and there shall be no depressions in horizontal surfaces of the finished waterproofing. Projections or depressions on the surface on which the membrane is to be applied that may cause damage to the membrane shall be removed or filled as directed by the Engineer. The surface shall be cleaned of dust, dirt, grease, and loose particles, and shall be dry before the waterproofing is applied. Concrete surfaces shall not be waterproofed until a period of at least seven days has elapsed after the placing of the concrete, unless otherwise approved by the Engineer.

There shall be no depressions or pockets in horizontal surfaces of the finished waterproofing. The membrane shall be carefully turned into drainage fittings. Special care shall be taken to make the waterproofing effective along the sides and ends of girders and at stiffeners, gussets, and all other plates where the membrane terminates.

Bituminous membrane waterproofing shall not be applied when the atmospheric temperature is below 50 °F (10 °C) and butyl rubber membrane shall not be applied when the atmospheric temperature is below 10 °F (-12 °C), without written permission of the Engineer.

Surfaces of concrete or steel that are to be waterproofed shall be given one coat of Asphalt Primer (RC-70) before the first mopping of Asphalt (AWP), except that at construction and expansion joints where insulation is to be used, the surfaces shall not be coated with primer. The primer shall be applied to the surface in a uniform coating and may be applied without heating. A minimum of 1 gal (4 L) of primer per

Membrane Waterproofing for Railway Structures Art. 580.04 505 100 sq ft (10 sq m) of surface shall be used. The priming coat shall be applied at least 24 hours before applying the waterproofing membrane and it shall be dry before the first mopping of bitumen is applied.

The primer shall be omitted for a width of 9 in. (225 mm) on each side of construction and expansion joints and a strip of insulating paper 18 in. (450 mm) wide shall be laid thereon before the waterproofing is applied. Insulating paper shall be a waterproof paper weighing not less than 10 lb/100 sq ft (0.5 kg/sq m).

Expansion joints and grooves shall be dry and clean; and shall be filled with plastic cement. Expansion joints and grooves filled with plastic cement shall be overfilled to allow for shrinkage.

580.04Membrane Application. Bituminous and butyl rubber membranes

shall be applied as specified.

of fabric shall be laid vertically or with the slope; on other surfaces the strips shall be laid horizontally, beginning at the lowest part of the surface to be waterproofed. Sufficient fabric shall be allowed for anchorage at the upper edge of the surface to be waterproofed.

Surfaces to be waterproofed shall be mopped in sections. While the first mopping of bitumen is still hot, a strip of fabric shall be laid on the mopping and pressed into place. Each mopping thereafter shall be applied so that it will completely cover and seal the fabric. The amount of bitumen used for each mopping shall be not less than 4 1/2 gal/100 sq ft (1.8 L/sq m) of surface. The bitumen for mopping shall be heated to a temperature which will permit uniform application. Asphalt shall not be heated above a temperature of 350 °F (175 °C).

Asphalt (AWP) shall be used for mopping asphalt saturated cotton fabric.

Application of bituminous membrane shall be started by mopping a section of the surface 2 in. (50 mm) wider than 1/3 of the width of fabric. On this hot mopping, a 1/3 width of fabric shall be laid. The top surface of this fabric and an adjacent section of the surface 2 in. (50 mm) wider than 1/3 width of fabric shall then be mopped. On this hot mopping, a 2/3 width of fabric shall be laid completely covering the first strip. The top surface of this fabric and an adjacent section of the surface 2 in. (50 mm) wider than 1/3 width of fabric shall then be mopped. On this hot mopping shall be laid a full width of fabric completely covering the first and second strips. The top surface of this fabric and adjacent section, the width of 1/3 width of the fabric, shall then be mopped. On this hot mopping, the second full strip of fabric shall be laid lapping the first 1/3 width of the fabric at least 2 in. (50 mm). Thereafter, full widths of fabric shall be laid in hot moppings of bitumen and in such manner that each strip will lap the third preceding strip at least 2 in. (50 mm). Side laps shall be not less than 2 in. (50 mm) and end laps not less than 12 in. (300 mm).

The bituminous membrane shall be free from punctures, pockets or folds, and patching shall not be done without the permission of the Engineer.

Art. 580.04 Membrane Waterproofing for Railway Structures 506 Where patching is permitted for defective waterproofing, the first ply shall extend at least 12 in. (300 mm) beyond the defective portion. The second and each succeeding ply of the patch shall extend at least 3 in. (75 mm) beyond the preceding ply.

The work shall be regulated so that at the end of the day all fabric that has been laid shall have received the final coat of bitumen, except that the fabric for making the lap shall not be mopped with bitumen until the joint is to be completed. With the approval of the Engineer, spraying will be permitted in lieu of mopping.

secured in a hot mopping of bitumen applied over the primed surfaces. When the surface has been primed using RC-70, the mopping shall be with asphalt (AWP). An adhesive, compatible to the membrane and other materials, may be used in lieu of the hot mopping of bitumen, at the option of the Contractor. If adhesive is used, it shall be applied to the areas to be waterproofed in a thin layer with a squeegee at a rate of 1 gal/100 sq ft (0.4 L/sq m).

Membrane sheets shall first be positioned and drawn tight without stretching. Half of the membrane sheet shall then be uniformly rolled up in a direction away from the starting edge or subsequent splice. The bitumen or adhesive shall now be applied to the exposed area. If adhesive is used, it shall be allowed to dry so as not to stick to a dry finger touch. The membrane shall then be unrolled and pressed firmly and uniformly in place, using care to avoid trapping air. The same procedure shall be used for the remaining half of the membrane sheet. Wrinkles and buckles shall be avoided. Each succeeding sheet shall be positioned to fit the previously installed sheet and spliced.

Splices shall be of tongue-and-groove or lap type. All seam, lap, and splice areas shall be cleaned with heptane, hexane, toluene, trichlorethlene, or white gasoline, using a clean cloth, mop, or similar synthetic cleaning device. Rubber cement shall be spread continuously on seam, lap, and splice areas at a uniform rate of not less than 2 gal/100 sq ft (0.8 L/sq m). After the rubber cement is allowed to dry until it will not stick to a dry finger touch, butyl gum tape shall be applied to the cemented area of membrane. The tape shall be extended at least 1/8 in. (3 mm) beyond edges of splice and lap areas. The tape shall be rolled or pressed firmly into place so full contact is obtained. Bridging and wrinkles shall be avoided. Corner splices shall be reinforced with two continuous layers of rubber membrane over one layer of butyl tape.

All projecting pipe, conduits, and sleeves passing through butyl rubber membrane waterproofing shall be flashed with prefabricated or field- fabricated boots or fitted coverings, as necessary to provide watertight construction. Butyl gum tape shall be used between layers of rubber membrane.

Any holes in the membrane sheeting shall be patched with a minimum overlap of 4 in. (100 mm) and according to the manufacturer's instructions.

Membrane Waterproofing for Railway Structures Art. 580.05 507 During construction, care shall be exercised to prevent damage to the membrane by workers or equipment.

580.05Protective Cover. The protective cover shall be placed over the

membrane as soon as practicable after the membrane has been laid. Dirt and other foreign material shall be removed from the surface of the membrane before the protective cover is placed.

At expansion joints of decks protected with butyl rubber membrane, a strip of anti-bonding paper 18 in. (450 mm) wide shall be laid above and below the membrane before the protective cover is applied.

One of the following methods of protection shall be used.

mopping of asphalt with all joints filled with asphalt.

thickness.

For bituminous membrane, the asphalt plank protection shall be laid in hot asphalt (AWP). The asphalt shall be applied at the rate of not less than 5 gal/100 sq ft (2 L/sq m) of surface. As successive planks are laid, the edges and ends of adjacent planks already laid shall be coated heavily with hot asphalt. The planks shall be laid tight against those previously laid so that the asphalt will completely fill the joints and be squeezed out at the top. After all planks are laid, any joints not completely filled shall be filled with hot asphalt. The ends of adjacent planks shall be staggered.

For butyl rubber membrane, the asphalt plank shall be laid in a coating of bonding adhesive. The bonding adhesive shall be the same as that used for securing the membrane to the deck. The adhesive shall be applied at a rate of not less than 1 gal/100 sq ft (0.4 L/sq m). Voids between the joints shall be filled with a compatible material.

Asphaltic panels are available in various thicknesses. To obtain the thickness of 3/4 in. (19 mm) required, the recommended application is in two layers with the joints staggered. The panels shall be laid tight jointed with an approved adhesive. For bituminous membrane, the asphaltic panels shall be laid in hot asphalt (AWP) and for butyl rubber membrane, the panels shall be laid in a coating of bonding adhesive. The application rate shall be the same as previously specified for asphalt planks. Any voids between the panels shall be filled with a material compatible to both the membrane and the panel.

When asphaltic panels are used as a protective cover, a 2 in. (50 mm) layer of fine aggregate shall be placed over the panels as a cushion prior to placement of ballast. The cost of this cushion shall be included in the bid price for membrane waterproofing. .

Art. 580.06 Waterproofing Membrane System 508

580.06Method of Measurement. This work will be measured for payment as

follows.

shall conform to Article 202.07(a).

payment in place, and the area computed in square feet (square meters). The area for measurement will include only the surface of the membrane waterproofing covered with a protective cover.

580.07Basis of Payment. This work will be paid for at the contract unit price

per square foot (square meter) for MEMBRANE WATERPROOFING.

SECTION 581. WATERPROOFING MEMBRANE SYSTEM

581.01Description. This work shall consist of furnishing and placing a

waterproofing membrane system over a properly prepared concrete bridge deck prior to placing of the hot-mix asphalt (HMA) surface course.

581.02Materials. Materials shall be according to the following

Item Article/Section

Note 1. The waterproofing membrane system shall consist of a penetrating primer, a built-up coal tar pitch emulsion membrane with two plies of coated glass fabric, and a 1/2 in. (13 mm) thick asphalt sand seal protection layer.

CONSTRUCTION REQUIREMENTS

581.03General. All methods employed in performing the work and all

equipment, tools, and machinery used for handling materials and executing any part of the work shall be subject to approval of the Engineer before the work is started, and whenever found unsatisfactory, shall be changed or improved as required. All equipment, tools, machinery, and containers used shall be kept clean and maintained in a satisfactory condition.

581.04Preparation of Concrete Deck. All surfaces which are to be covered

shall be thoroughly cleaned by the use of air jets, water jets, mechanical sweeper, hand brooms, or other approved methods, or as required by the Engineer until the surface is free of all sand, clay, dust, salt deposits, and all loose or foreign matter. Any accumulations of oil or grease shall be scraped off the surface of the roadway after which those areas shall be cleaned with a strong caustic solution, the residue of which shall be thoroughly flushed away with clean water before application of the primer.