4-85 10(B) for the remaining joints.
455-5 Measurement and Payment
Precast Gravity Retaining Walls will be measured and paid in square feet. Precast gravity walls will be measured as the square feet of wall face area with the pay height equal to the difference between top of wall and top of footing elevations. Define “top of wall” as top of PRW cap or top units. The contract unit price for Precast Gravity Retaining Walls will be full compensation for providing design, submittals, labor, tools, equipment and precast gravity wall materials, excavating, hauling and removing excavated materials , placing and compacting backfill material and supplying footings, PRW units, select material , wall drainage systems, geotextiles, PRW cap and top units, slope protection and any incidentals necessary to construct precast gravity walls. No separate payment will be made for temporary shoring for wall construction. Temporary shoring for wall construction will be incidental to the contract unit price for Precast Gravity Retaining Walls . The contract unit price for Precast Gravity Retaining Walls does not include the cost for ditches, fences, handrails, guardrail or barriers associated with precast gravity walls as these items will be paid for elsewhere in the contract. Where it is necessary to provide backfill material behind No. 57 stone fr om sources other than excavated areas or borrow sources used in connection with other work in the contract, payment for furnishing and hauling such backfill material will be paid as extra work in accordance with
Article 104 — 7. Placing and compacting such backfill material is not considered extra work but
is incidental to the work being performed. Payment will be made under: Pay Item Pay Unit Precast Gravity Retaining Walls Square Foot
458-1 Description
Waterproof or dampproof concrete surfaces in accordance with these specification s for the particular method of waterproofing or dampproofing called for in the plan s. Furn ish and apply all asphalt, tar, fabric, asphalt plank and any other materials.
458-2 Materials
Refer to Division 10. Item Section Asphalt Binder 1020 -7(B) Asphalt Primer 1020 -7(A) Tar 1020 -7(C) Woven Cotton Fabric 1020 -7(D)
458-3 Method A Waterproofing
A.General Method A waterproofing consists of one coat of asphalt primer, and 3 mop coats of hot asphalt cement with 2 layers of cotton fabric alternating between the mop coats.
4-86 (B) Preparation of Surface
Ensure that concrete surfaces are dry, reasonably smooth and free from projections or holes which are capable of puncturing the membrane. Immediately before applying the waterproofing, thoroughly clean the surface of dust and loose materials. Make sure that the concrete is at least 14 days old for Class A concrete, at least 10 days old for Class AA concrete, or at least 7 days old for high e arly strength concrete, before beginning waterproofing. Do not waterproof in wet weather nor when the temperature is below 35° F, without permission from the Engineer .
C.Application Give waterproofed surfaces a thorough coat of asphalt primer, and allow it t o set thoroughly before applying the first mop coat. Heat the asphalt cement for the mop coat to a temperature of at least 300° F and frequently stir to avoid local overheating. Equip the heating kettles with thermometers. Begin the waterproofing at the low point of the surface. Use a half width first strip of fabric; and a full width second strip. Lap the full width of the first strip. Make the third and each succeeding strip full width and lap so there are 2 layers of fabric at al l points with laps at least 2 inches wide. Make sure that the end laps are at least 12 inches . Beginning at the low point of the surface, mop a section about 20 inches wide and the full length of the surface with hot asphalt cement. Immediately roll the first strip of fabric into the asphalt cement and press into place to eliminate all air bubbles and to provide a firm bond to the surface. Mop this strip and an adjace nt section of the surface of a width equal to slightly more than half the width of the fabric with hot asphalt binder and roll a full width of the fabric into this cement, completely covering the first strip, and press into place. Mop this second strip and an adjacent section of the concrete surface with hot asphalt cement and place the third strip of fabric to lap the first strip at least 2 inches . Continue this process until the entire surface is covered, each strip of fabric lapping at least 2 inches over the second preceding strip. Give the entire surface a final mopping of hot asphalt cement. Mop on concrete to completely cover the surface sufficiently heavy on cloth to completely conceal the weave. Use at least 12 gallons of asphalt on horizontal s urfaces for each 100 square feet of finished work and at least 15 gallons on vertical surfaces. Perform the work so, at the close of a day's work, all laid cloth receives the final mopping of asphalt. Thoroughly seal down all laps.
D.Special Requirements At the edges of the membrane and at any points punctured by such appurtenances as drains or pipes, make suitable provisions to prevent water from getting between the waterproofing and the waterproofed surface. Place all membrane flashing at curbs and agains t girders, spandrel walls, etc., with separate sheets of membrane lapping the main membrane at least 12 inches . Closely seal flashing with either a metal counter -flashing or by embedding the upper edges of the flashing in a groove poured full of joint fil ler. Provide expansion joints, both horizontal and vertical, with water stops and premolded joint filler as called for in the plan s. Seal expansion joints in the face adjacent to the membrane bituminous material. Carry the membrane continuously across al l expansion joints. At the ends of the structure carry the membrane well down on the abutments and make suitable provisions for all movement.
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 221–222 of 857.