344Membrane forming curing compounds may be used providing they do not conflict with

601.12.2 Curing Under Cold Weather Conditions: When the air temperature is

expected to fall below 30F, the Contractor shall provide suitable measures to maintain the concrete surface temperature between 50 F and 90F. Calendar days on which the surface temperature of the concrete falls below 50 F shall not be considered days of curing. In no event shall the temperature of the concrete be allowed to fall below 35 F before the specified curing is completed. The Contractor shall be responsible for the quality and strengths of the concrete placed or cured, or both, during the cold weather, and any con crete injured by frost action shall be removed and replaced at the Contractor's expense. When protection is removed from the structure after the specified curing is complete, the temperature of the concrete shall not be permitted to fall at a greater rat e than 20F per 24 hour period. Class H or Class K Concrete Provisions: The surface temperature of the concrete shall be maintained between 55 and 75°F for 72 continuous curing hours immediately after placement. After this 72 hour period, a minimum concrete surface temperature of at least 50°F shall be maintained for an additional 96 continuous curing hours. If it is expected that the surface temperature of the concrete will drop below 50°F during the 168 hour curing period, then the surfac e shall be enclosed and external heat shall be provided in accordance with the provisions of this section. Once external heat provisions are required, they shall remain on the surface until curing is complete, regardless of the ambient air temperature. Enc losures for heat retention shall be properly vented to prevent surface disintegration from carbon dioxide gas. Continuous wetting shall be replaced by wetting at regular intervals if, in the opinion of the Engineer, expected air temperatures could result in freezing of run -off water. 345 601.12.3 -Protection of Finished Surfaces: All exposed finished surfaces of concrete shall be protected to prevent rust stains, paint splotches, scars or other blemishes tending to disfigure or discolor the finished surfac e. Where reinforcing steel bars or other steel inserts are left exposed for extended periods or over the winter, they shall be given a coat of neat cement paste to prevent rust staining. Water runoff from concrete curing operations shall be deflected awa y from the steel girders and shall not drain onto the substructure concrete after contacting the weathering steel. Any stains or other blemishes shall be corrected by the Contractor.

601.12.4 Curing Class H Concrete: It is the nature of Class H concr ete material to quickly

form a plastic film at the surface upon drying. This film is to be protected from drying and cracking by prompt covering with wet burlap. Regardless of the type of concrete placed, the use of membrane curing compounds will not be allowed. Floor drains shall be immediately unplugged to permit the deck to drain. The concrete surface shall be completely covered with clean, wet burlap. The burlap shall be thoroughly saturated over its entire area, but shall be drained of excess water before application. Burlap shall be lapped a minimum of one foot and shall lay flat. Failure to apply wet burlap within 30 minutes after discharge of the concrete from the truck and within 10 minutes of the completion of finishing operations shall be cause for rejection of the work as determined by the Engineer. Care shall be exercised to ensure that the burlap is well drained. Burlap shall be continuously wet for a period of seven days by means of automatic intermittent sprinkling or a continuous wetting system.

601.12.5 Protecting Concrete Decks: Construction equipment with an axle load greater than

20,000 lbs shall not be permitted on bridge deck. Construction equipment or loads that are not required to complete the slab, parapets, railing overlay, or other appurtenances shall not be allowed on the bridge deck.

601.13 Protective Surface Treatment :

601.13.1 Silane Treatment for Bridge Superstructure: After the concrete has achieved

a minimum of 80% of the design strength, a silane protective treatment as specified shall be applied to the entire top surface of bridge decks, approach slabs when they are included in the Contract, concrete bridge medians, top and curb face of bridge sidewalks, and the inside faces of parapets. When approach slabs are specified to be overlayed with asphalt, the sila ne treatment is not required. The application of this silane protective surface treatment is not required for elements constructed from Class H concrete. The surface to receive the treatment shall be dry for at least 48 hours before treatment and shall be free from sand, surface dust and dirt, oil, grease, chemical films, and other contaminants prior to application of the silane. Immediately before application, the entire surface shall be air blown to remove any loose dust. The surface, air, and mater ial temperatures shall be between 40 and 100° F during application, and temperatures above 40° F, without precipitation, must be forecast for the twelve hours following application. Any coating damaged by rain or moisture shall be corrected by an addition al application. The surface treatment shall consist of one of the silane sealers listed on the Division’s Approved Product List of Concrete Sealers. The surface treatment, including application rate, shall be applied in accordance with the requirement s listed above and the Manufacturer’s recommendations. Metal hand rails shall be protected from spray by shielding or masking. 346 The Contractor shall prohibit all pedestrian and vehicular traffic on the structure during the drying period of the protect ive coating.

601.13.1 1 -Silane Treatment for Bridge Substructure: Before placing any steel

superstructure members on the concrete substructure units, the Contractor shall coat all exposed areas of the abutment, tops, sides, and all faces of pier caps an d pier stems to the ground or water line elevation with an approved silane based concrete sealer except for projects where concrete protective or other coatings are specified. Preparation of surfaces, application rates, and methods shall be as recommended by the silane manufacturer. Upon completion of all superstructure concrete curing operations, the Contractor shall remove all stains from substructure units using proprietary chemical stain removers and/or mild acid etching. Abrasive blast cleaning shal l be used to supplement the other cleaning methods to completely remove all stain s if the stained areas are severe or extensive. All cleaning methods shall be subject to approval of the Engineer. Re-coat all areas where stains were removed, regardless of the cleaning method used, with an approved silane based concrete sealer as specified above.

601.13.2 Epoxy Resin Protective Coating: The top surface of abutment bridge seats,

including drainage areas, and the adjacent bottom six (6) inches of the backwall and the top surface of pier caps which are located beneath expansion devices shall receive an epoxy resin protective coating. The area immediately beneath the bearing masonry plates may be omitted at the Contractor's option. Concrete surfaces to be coated shall be sound, dry and free of all laitance and curing materials. The coating shall not be applied until the concrete has atta ined the age recommended by the manufacturer. When required by the Engineer in the field, concrete surfaces shall be cleaned of all oil, grease and other potential bond inhibiting matter by acid etching with a 10 percent (10%) to 15 percent (15%) muriati c acid solution. The acid solution shall be spread and allowed to react until bubbling has subsided, approximately three to five minutes. The surface shall then be thoroughly flushed with clear water and allowed to dry. Where, in the opinion of the Engine er, acid etching is insufficient to clean the concrete, then sandblasting or an approved method of mechanical abrading shall be required. The exact indicated amounts of the base polymer and the reacting system, as recommended by the manufacturer, shall b e measured into mixing container and mixed thoroughly with a low-speed paddle -type mixer. After mixing, the material shall stand for an induction period of one hour before application. Following the one hour induction period, the mixed protective coatin g may be applied by brush, roller or spray. When applied by roller, a first quality, long nap roller is recommended for rough surfaces, and a short nap roller for smooth surfaces. If applied by spray, an externally atomized spray gun is recommended. If thinning is necessary for spray application, thinner shall be of the type and amount recommended by the coating manufacturer. Two coats of mixed material shall be applied in thin, uniform coats of approximately 2 to 3 mil dry film thickness each (4 -5 mil s wet thickness). The second coat shall be applied approximately 24 hours after the application of the first coat. One gallon of the system will cover approximately 275 square feet of smooth concrete, first coat; a second coat will cover approximately 40 0 square feet. In all cases application shall be made at temperatures recommended by the manufacturer.