251 In all cases in which curing requ ires the use of water, the curing shall have prior right to the use of all water supplies. Failure to provide sufficient curing materials of whatever kind the Contractor may elect to use will be cause for immediate suspension of concreting operations. Th e concrete shall not be left exposed for more than 30 minutes between stages of curing or during the curing period. Concrete placed in cold weather, as defined in 501.21, shall be cured a minimum of seven calendar days or when the Contractor provides suit able means for documenting the maturity (degree -hours) of the concrete, based on slab surface temperature, the curing period may be terminated when the curing has been maintained for a minimum of 7,000 degree hours. During the curing period the surface te mperature of the concrete shall not be allowed to fall below freezing. The Contractor shall be responsible for the quality of the concrete placed or cured, or both, during cold weather. Any concrete injured by frost action shall be removed and replaced a t the Contractor's expense. Polyethylene coated burlap and white polyethylene sheeting will be permitted as a curing application only on areas where intimate contact with the concrete surface can be obtained and maintained.
501.14.1 Burlap Mats: The s urface of the pavement shall be entirely covered with the
mats. The mats shall be of such length that they will extend at least twice the thickness of the pavement beyond the edges of the slab. The mat shall be placed so that the entire surface and both edges of the slab are completely covered. Before placing, the mats shall be thoroughly saturated with water. The mats shall be weighted down so as to remain in intimate contact with the surface covered and shall be maintained fully wetted and in pos ition for 72 hours after the concrete has been placed, unless otherwise specified.
501.14.2 Waterproof Paper: The top surface and sides of the pavement shall be entirely
covered with waterproof paper. The units shall be lapped at least eighteen ( 18) inches. The paper shall be weighted down so as to remain in intimate contact with the surface. Each unit as laid shall extend at least twice the thickness of the pavement beyond the edges of the slab. Paper not manufactured in sizes providing this width shall be securely sewed or cemented together, the joints being securely sealed in such a manner that they do not open up during curing. The surface shall be thoroughly wetted before placing the paper. Curing shall continue for 72 hours after the concrete is placed, unless otherwise specified.
501.14.3 Straw Curing: When this type of curing is used, the pavement shall be cured
initially with burlap or cotton mats, as specified above, until after final set of the concrete or, in any case, for 12 hours a fter placing the concrete. As soon as the mats are removed, the surface and sides of the pavement shall be thoroughly wetted and covered with at least eight (8) inches of straw or hay, thickness to be measured after wetting. The straw or hay shall be kep t thoroughly saturated with water for 72 hours after placing the concrete. If the straw or hay becomes displaced during the curing period, it shall be replaced to the original depth and saturated. Upon removal, the covering shall be disposed of in such a manner as to leave the right -of-way in a neat condition. The straw or hay shall not be burned on, or adjacent to, the pavement.
501.14.4 White Pigmented Impervious Membrane : The entire surface of the pavement
shall be sprayed uniformly with white pigmented curing compound immediately after the finishing operation and before initial set has taken place, or, if the pavement is initially cured 252 with burlap or cotton mats, it may be applied upon removal of the mats. The curing compound shall not be applied during rainfall. Curing compound shall be applied under pressure by mechanical sprayers. The spraying equipment shall be of the fully atomizing type equipped with a tank agi tator. The rate of application of the curing compound shall be as follows:
1.Pavement with Burlap Drag Finish -One Gallon Per Maximum of 150 sq. ft.
2.Pavement Requiring Groove Finish -One Gallon Per Maximum of 125 sq. ft. For unbonded concrete overlays, th e curing compound application rates noted below shall be doubled. At the time of use, the compound shall be in a thoroughly mixed condition with the pigment uniformly dispersed throughout the vehicle. During application the compound shall be continuousl y agitated. Hand spraying of odd widths or shapes and surfaces exposed by removal of forms will be permitted. Curing compound shall not be applied to the inside faces of joints to be sealed. Should the film become damaged from any cause within the requ ired curing period (72 hours after placement of concrete, unless otherwise specified), the damaged portions shall be immediately repaired with additional compound. Upon removal of the side forms, the sides of the exposed slabs shall be protected immediat ely with a curing treatment equal to that provided for the surface.
501.14.5 White Polyethylene Sheeting or Polyethylene Coated Burlap: The top surface
and sides of the pavement shall be entirely covered with polyethylene sheeting or polyethylene coated burlap. Units shall be lapped at least eighteen ( 18) inches. The covering shall be weighed down so as to remain in intimate contact wi th the surface covered. The covering shall extend at least twice the thickness of the pavement beyond the edges of the slab. The covering shall be maintained in place at least 72 hours after the concrete is placed, unless otherwise specified.
501.15 Removing Forms :
Forms shall not be removed until at least 12 hours after placement of the concrete. Forms shall be removed carefully so as to avoid damage to the slab. As soon as the side forms have been removed, minor honeycombed areas shall be filled with mortar composed of one part cement to two parts fine sand and cured as outlined in one of the methods indicated above. Major honeycombed areas shall be removed and replaced. All areas or sections so removed shall be not less than ten ( 10) feet in length nor less than the full width of the traffic lane involved. Any remaining portion of the slab adjacent to the joints that is less than ten (10) feet in length shall also be removed and replaced. Slabs shall be cut by sawing full depth for removal.
501.16 Sealing Joints :
All transverse contraction and construction joints to be sealed shall have the preformed elastomeric seal installed or shall be filled with silicone sealer before the pavement is opened to traffic, including construction traffic, and as soon after completion of curing as is feasible. All longitudinal joints shall be sealed with silicone seala nt. Cleaning and sealing of all joints is not required unless shown in the Plans.
501.16.1 Silicone Sealant: Following forming, initial sawing and final or second -step
sawing operations, the joints shall have been cleaned in accordance with subsectio na 501.11.8. In preparation for sealing, all joints that have become contaminated since those forming or
Source: West Virginia Standard Specifications for Road and Bridge Construction, 2023 Edition. Pages 269–270 of 1,006.