SECTION 504 – STRUCTURAL CONCRETE
504.01 Description
This Section describes the requirements for constructing cast-in-place concrete. This Section also describes the requirements for the application of color stain and primer to concrete structures and staining other areas as described herein and as shown on the plans.
504.02 Materials
504.02.01 Materials
Provide materials as specified: Grit for Epoxy Waterproofing................................ ................................ ................................ ................... 901.07.01 Concrete ................................ ................................ ................................ ................................ ...................... 903.03 High Performance Concrete ................................ ................................ ................................ .......................... 903.05 Mortar................................ ................................ ................................ ................................ ...................... 903.08.01 Curing Materials ................................ ................................ ................................ ................................ .......... 903.10 Reinforcement Steel ................................ ................................ ................................ ................................ ..... 905.01 Welded Wire Reinforcement ................................ ................................ ................................ .................... 905.01.03 Concrete Stain ................................ ................................ ................................ ................................ .......... 912.01.04 Epoxy Waterproofing ................................ ................................ ................................ ............................... 912.02.02 Preformed Joint Filler ................................ ................................ ................................ ................................ ... 914.01 Joint Sealer (Hot-Poured) ................................ ................................ ................................ ............................. 914.02 Waterstops ................................ ................................ ................................ ................................ ................... 919.06
504.02.02 Equipment
Provide equipment as specified: Sealer Application System ................................ ................................ ................................ ........................... 1003.08 Spreading and Finishing Machine ................................ ................................ ................................ ................ 1005.02 Vibrator ................................ ................................ ................................ ................................ ...................... 1005.04 Straightedge ................................ ................................ ................................ ................................ ................ 1008.02 Pavement Saw ................................ ................................ ................................ ................................ ............. 1008.04 Hot-Air Lance ................................ ................................ ................................ ................................ ............. 1008.06 Concrete Batching Plant ................................ ................................ ................................ .............................. 1010.01 Concrete Trucks ................................ ................................ ................................ ................................ .......... 1010.02
504.03 Construction
504.03.01 Reinforcement Steel
A.Handling. Store reinforcement steel above ground level. When unloading coated reinforcement steel, minimize scraping of the bundles, bar-to-bar abrasion, and sags in the bundles. For coated reinforcement steel, do not skid the bundles from the truck bed to the ground. Ensure that equipment used for handling the bars is equipped with nylon slings. Do not use wire rope slings or chains. Lift bundles of bars to ensure that sagging does not occur. Ensure that coated bars or bundles of coated bars are not dropped or dragged during handling.
B.Storing. Coordinate deliveries of coated reinforcement bars to the work site with the placing of the bars in the structure. Store reinforcement steel as close as possible to the area where it will be placed to minimize handling. Store the bars above the ground on timbers or other suitable protective cribbing and space the dunnage to prevent sags in the bundles. When storing a large quantity of bars in a small area, stack bundles of straight bars with adequate blocking placed between the layers of bundles to provide stability and prevent sagging. Do not store reinforcement bars at the work site for more than 60 days unless approved by the RE. If long ter m storage is approved, protect non-metallic tags on the bundles or attach additional galvanized metal tags on all bundles of bars to maintain identification. If long term storage is approved, cover the bars with white polyethylene sheeting or other suitable protective material. For stacked bundles, drape the white polyethylene sheeting over the sides of the bundles around the perimeter of the stack. Secure the covering and provide air circulation around the bars to prevent condensation under the polyethylene sheeting.
C.Field Cutting. Obtain RE approval before field cutting reinforcement steel. Do not flame cut epoxy -coated reinforcement steel. If coated reinforcement bars are cut in the field, coat the cut en ds and repair damage to the coating as specified in 504.03.01.G.
D.Field Bending. Obtain RE approval before field bending reinforcement steel. Use the cold method to make minor adjustments to reinforcement steel bars in the field. Do not bend galvanized reinforcement steel more than 10 degrees. With the approval of the RE, the Contractor may use the heat method to perform minor adjustments to uncoated bars. Preheat the bar to between 1,000 and 1,200 °F, and then gently bend in a gradual arc. For bars partially embedded in concrete, ensure that the concrete is not damaged by heating the bars.
E.Placing and Fastening. When placing, ensure that reinforcement steel is free of dirt, detrimental scale, paint, oil, or other foreign substances. Tie bars at all intersections except where spacing is less than 12 inches in each directi on, in which case tie alternate intersections. Use stays, blocks, ties, hangers or chairs, to maintain the specified concrete cover. If using blocks, ensure that the blocks are precast concrete. Ensure that blocks are not used where they are exposed in a finished surface. When using galvanized reinforcement steel, ensure that all miscellaneous hardware that comes in contact with or is used to support, position, or fasten the reinforcement steel are also galvanized according to AASHTO M 232. When using e poxy-coated reinforcement steel, use only plastic -coated or epoxy -coated tie wires and ensure that all miscellaneous hardware used to support, position, or fasten the reinforcement are dielectric, plastic -coated, or epoxy-coated. If using welded wire reinforcement, overlap sheets at least 1 grid in width. Fasten overlaps securely at the ends and edges. Repair damage to epoxy -coating or galvanized coating as specified in 504.03.01.G. Do not place concrete before inspection and approval of the reinforcement steel.
F.Splices. When splicing is not specified, submit a plan for splicing to the RE for approval. Include size, location, and splicing method. The Contractor may use mechanical coupling devices listed on the QPL. When using galvanized reinforcement steel, ensure that mechanical coupling devices are galvanized according to AASHTO M 232. When using epoxy -coated reinforcement steel, ensure that mechanical coupling devices are epoxy coated according to AASHTO M 284. When using mechanical connections, remove the coating from the ends of the reinforcement steel over the length of the sleeve and at least 2 inches from the ends of the sleeves, or more if recommended by the Supplier. Repair damage to epoxy-coating or galvanized coating as specified in 504.03.01.G.
G.Field Repairing of Coatings. The RE will allow field repair when there are less than 6 damaged areas in any 10 foot length of bar. The RE will reject material with more t han 6 damaged areas within a 10 feet span and any material with a damaged area more than 4 square inches in si ze. Repairable damage is any bare or loose spots, or breaks in the coating that affect an area smaller than 4 square inches. Ensure that grease, dirt, mortar, concrete, mill scale, injurious rust, or any other foreign substance is removed before repairing.
1.Epoxy-Coating. Repair damage to epoxy-coating according to AASHTO M 317.
2.Galvanized-Coating. Repair damage to the galvanized coating according to ASTM A 780.
H.Protecting Exposed Reinforcement Steel. When non-coated embedded reinforcement steel is partially exposed at construction joints for more than 30 days, protect the exposed portion of the bar with a coat of neat cement mixed with water within 5 days of the initial concrete placement. Remove loose coating by lightly tapping within 5 days of the subsequent concrete placement.
504.03.02 Concrete
A.Falsework. When forms and concrete require support, construct falsework on sills resting on foundations capable of carrying the loads without settlement. If falsework cannot be founded on solid footings, support with falsework piling. Construct the falsework to support the forms and the structure so that there is no deflection. Provide camber in the falsework and forms to allow the joints to tighten in the forms and supporting falsework. When constructing centering for arches, correct any deflection due to placing the concrete by jacking, as the concrete is being placed.
B.Forms. Construct forms that are true to line and grade, are mortar tight, and provide a smooth, even concrete surface. Ensure that forms are rigid to prevent distortion. Prevent the opening of the joints or movement in any direction. Ensure that all bolts are countersunk on the face forming the concrete surface. Ensure that forms are free from rust, grease, and other foreign matter. Clean the top and face of forms, and oil the face before erecting. Ensure that the form oil does not discolor the concrete. Provide a system to monitor settlement or movement in the falsework and forms. Check the alignment and elevation of the forms and make corrections before placing the concrete. Reset or remove and replace forms that deviate from the specified line and grade. Provide a chamfer to form edges as shown. Ensure that all chamfer strips are straight, of uniform width, and dressed. Construct forms so that they can be removed without damaging the waterstops. S plice, weld, or solder metallic waterstops, as necessary, to form continuous, watertight joints. Install nonmetallic waterstops in continuous strips, without splices. The RE will allow splices at changes in direction when necessary. Splice nonmetallic w aterstops according to the manufacturer’s recommendations. When splicing PVC waterstops, ensure that the heat used is sufficient to melt but not char the plastic. Secure waterstops to prevent movement during concrete placement. When epoxy-coated reinforcement steel is used, use epoxy -coated or galvanized metal ties. When metal ties and anchorages remain in the forms, remove to a depth of at least 1 inch from the face without damaging the concrete. Provide cones if using wire ties. The Contractor may use manufactured fiber tubes as column forms for round columns of concrete. Ensure that fiber tubes are rigid and circular in section. Store fiber tubes above ground on supports in a dry area. Ensure that fiber tubes are not exposed to moisture before use. When erecting column forms, hold forms in a vertical position to prevent distortion during concrete placement.
C.Limitations of Placing. At least 30 days before placing concrete, submit to the RE for approval a plan for hot and cold weather concreting. Include the method that will be used to ensure that the temperature of the concrete is between 50 and 90 °F during mixing and placing. Do not place conc rete when precipitation is imminent as determined by the RE. If it begins precipitating during concrete placement, the RE may direct the Contractor to suspend placement operations and protect the plastic concrete as specified in 504.03.02.I. If placement cannot be resumed within 30 minutes, the RE may direct the construction of a construction joint. If, during the concrete placement or within the 24 hours preceding the scheduled concrete placement, the Nat ional Weather Service http://www.nws.noaa.gov/ locally forecasts the ambient temperature to be below 40 °F or above 75 °F during the scheduled concrete placement or curing period, f ollow the appropriate temperature condition procedure. Do not place concrete when the ambient temperature is below 20 °F or above 100 °F.
1.Cold Weather Concreting. The RE will prohibit the placement of concrete when the ambient temperature is below 40 °F, unless all surfaces in contact with the concrete placement are preheated to between 50 and 80 °F and access is provided for measuring the temperature of the in-place concrete. For access, establish a 1/2 inch diameter hole that is 6 inches deep at a 45 degree angle by placing a greased bolt through the forms prior to concrete placement. Use one or more of the following protective measures to maintain the concrete temperature:
a.Insulated Forms. Before placing concrete, construct insulated forms to protect concrete. Ensure that the forms are free of ice, snow, and frost at time of placing concrete.
b.Insulated Blankets. Use insulated blankets to protect concrete. Place the blankets on top of polyethylene sheeting within 30 minutes of placing concrete.
c.Heating and Housing. Before placing concrete in the forms, provide housing for the section of concrete to be placed so that the temperatures specified can be maintained withi n the enclosure. Construct the enclosures to allow removal of forms and finishing of concrete surfaces without interruption of the heating. Maintain the heating system to provide uniform heating within the enclosure. Ensure that the heating system has be en operating so that the temperature of form surfaces, reinforcement steel and abutting construction to be in contact with the concrete is between 50 and 80 °F before placing the concrete. Provide a sufficient number of back -up heaters at the Project Limit s to maintain the temperature of the housing in the event of a breakdown of the primary heating system. In the event of a breakdown, operate the back-up heaters until the primary heating system is repaired. Maintain the protective measures for arches, culverts, deck slabs, and approaches for at least 7 days. For other concrete placements, maintain for at least 5 days. Ensure that the temperature of the concrete is maintained between 60 and 160 °F for 5 days after placement. The RE will check the tempera ture of the concrete in the established hole. If the temperature of the concrete falls below 60 °F within 5 days after placing, maintain the protective measures in place for an additional 5 days. If the temperature of the concrete rises above 160 °F, the RE may direct the forms to be loosened or protective measures to be removed. If the temperature of the concrete falls below 32 °F or rises above 180 °F within 5 days of placement, the RE will direct that the concrete be removed and replaced. After the concrete temperature has been maintained for 5 days at a minimum of 60 °F, ensure that the temperature of the concrete does not fall more than 10 °F in 12 hours.
2.Hot Weather Concreting. When the ambient temperature reaches 75 °F, use the following procedures before and during concreting operations.
a.Schedule work so that concrete can be placed continuously. If necessary, start concrete placement at night or early morning.
b.Use a water-reducing admixture or a water-reducing and retarding admixture as specified in 903.02.02 and according to the manufacturer’s recommendation.
c.Prevent absorption by sprinkling the underlying material and the wood forms just before concrete placement so that they do not absorb water from the mix.
d.Begin curing within 5 minutes after finishing. If the temperature of the plastic concrete reaches 85 °F, take immediate steps to cool either the mixing water or the aggregates, or both, according to the plan of action. Do not place concrete when its temperature in the plastic state exceeds 90 °F at the time of placement.
D.Placing and Consolidating C oncrete. The Contractor may request 1 additional set of cylinders to be taken for determining strength for early form removal as specified in 504.03.02.G. If additional cylinders are requested, notify the RE at least 24 hours before placing. Appoint sufficient number of personnel, who are certified by the NJACI as Concrete Construction Technologists or by ACI as Concrete Transportation Construction Inspectors, to monitor daily operations for concrete placement. The certified personnel are responsible for ensuring proper dimensions of forms; position of reinforcement steel; proper handling, placement, consolidation, and finishing of concrete; and proper curing of the concrete. Ensure that all forms, joints, and reinforcement steel have been placed, inspected, and approved before placing concrete. Ensure that utilities, pipe, conduit, ducts , and any other items to be encased in concrete are in place and secure before placing concrete. Secure or provide rigid bracing for items to be encased in concrete during concrete placement to prevent their displacement. Ensure that forms for weep holes through concrete are PVC or unreinforced concrete drain pipe. Do not place concrete until all laitance and loose, deleterious material on reinforcement bars and previously placed concrete has been removed. Clean forms of all debris immediately before placing concre te. Wet the surfaces not treated with oil, paraffin, or epoxy bonding compound. Begin placing concrete at the lowest elevation and proceed upgrade. Place the concrete so that segregation does not occur and there is no displacement or movement of reinforcement and forms using one of the following methods:
1.Chutes and Troughs and Other Conveyances. Do not dump or drop concrete from a distance greater than 5 feet, unless using closed chutes or pipes to confine concrete. Ensure that buggies, chutes, troughs, and pipes used for placing concrete are kept clean and free from coatings of hardened concrete.
2.Pumped Concrete. At least 30 days before beginning operations, sub mit a plan to the RE according to ACI 304.2R. Include the method and procedures along with a list of adequate descriptions of equipment and manpower proposed for use, including contingency equipment and manpower. The RE will prohibit the use of aluminum alloy pipe as a conveyance for the concrete or for any pieces of equipment in contact with the concrete. For flatwork concrete, ensure that the pipeline is horizontal for at least 6 feet at the discharge end. If the concrete remaining in the pipeline is to be used, discharge the concrete in such a manner that there is no contamination or segregation. Take samples of the plastic concrete according to AASHTO T 141 from the discharge end of the pipeline. Immediately deliver the samples to the ME for testing. If the RE determines that this is not feasible, the ME will sample the concrete before and after pumping and will develop adjustment factors for slump and air content. The ME will use the adjustment factors to determine the acceptability of slump and air content. When using spreaders to separate forms, remove spreaders while placing the concrete. If the reinforcement steel or forms settle or move, cease placing concrete and immediately notify the RE. Place concrete uniformly to avoid rehandling. After initial placement of the concrete, do not jar forms or place strain on the ends of projecting reinforcement. Consolidate the concrete using internal mechanical vibrators. When required, supplement vibrating by hand spading to ensure proper and a dequate consolidation. Provide at least 1 additional standby vibrating unit for individual concrete placements in excess of 10 cubic yards. Use vibrators to work the concrete around the reinforcement steel and embedded fixtures and into corners and angles of the forms. Ensure proper vibration of the concrete to avoid honeycombing and voids. Do not use vibrators to move or spread concrete into position. Do not over vibrate concrete. Float the external surface of concrete during placing to force coarse aggregate from the surface and to bring mortar against the forms to produce a smooth finish substantially free from water and air pockets or honeycombs. For sidewalks, driveways, and islands, apply surface texture using a broom before applying curing materials. After placing concrete for elevated structures, check and, if necessary, adjust forms and falsework to the specified position before the concrete has taken its initial set. When placing concrete for bearing areas, finish concrete to the specified elev ation. If the elevation of the finished surface is higher than specified, bushhammer to the specified elevation. If the elevation of the finished surface is lower than specified, submit a plan to the RE for approval detailing the method to correct the deficiency. Monitor the internal temperature of the concrete 6 inches below the surface. If the temperat ure of the concrete exceeds 160 °F, the RE may direct the forms to be loosened or opened.
E.Placing Mass Concrete. When mass concrete is shown on the Plans submit a thermal curing plan to the RE for approval at least 30 days before placing concrete. At a minimum, include the following requirements in the plan:
1.Concrete mix design, including pozzolanic materials to control concrete temperature.
2.Adjustments to form removal and loading times for slower strength gains for high pozzolan mixes.
3.An analysis of the anticipated thermal develo pments within placements using proposed materials and casting methods.
4.A plan outlining specific measures to be taken to control the temperature differential within the limits.
5.The proposed monitoring system.
6.Outline of corrective actions to control the temperature differential and maximum internal temperature.
7.Contingency plan if the concrete exceeds the 35 °F differential.
8.Proposed methods of repairs or corrective actions if the mass concrete member is not accepted. Place concrete as specified in 504.03.02.D. When curing concrete, ensure that the temperature differential of the mass concrete does not exceed 35 °F between the internal and external temperature of concrete. Measure the internal temperature as close as possible to the center of the member, but not less than 12 inches from the surface. Measure the external temperature of the concrete at an exposed surface. Monitor the temperature differential and the maximum internal temperature with monitoring devices that continuously record temperature for 15 days. Provide the RE with a copy of each set of readings. Provide temperature-monitoring devices to record temperature between the interior and exterior of the member at poi nts approved by the RE and monitor the mass placement to measure temperature differentials. Monitor the temperature until the interior temperature is within 35 °F of the lowest ambient temperature or a maximum of 15 days. Provide the RE with a copy of each set of readings as they are taken and a temperature chart for each mass placement member showing temperature readings versus time. If monitoring indicates that the proposed measures are not controlling the concrete temperature differential to within 35 °F and the maximum internal temperature of 160 °F, implement corrective actions according to the thermal curing plan to maintain the temperature differential.
F.Applying Curing Materials. After float finishing and when marring of the concrete will not occur, apply curing materials within 30 minutes after finishing. The RE will suspend concrete operations if the curing procedure is delayed or is not followed. Cure the concrete using the following materials:
1.Curing Compound. Apply 2 coats of curing compound, as provided by the manufacturer, each at a rate of 1 gallon per 200 square feet of surface in a continuous, uniform film with pressure spraying equipment. Do not apply curing compound to exposed construction joint areas. Apply the second coat between 15 and 30 minutes of applying the first coat. If the method of applying the curing compound produc es a nonuniform film, discontinue application and correct the procedure. If the procedure cannot produce the required results, use another curing option. Protect the treated surface, as specified in 504.03.02.I, from damage for at least 72 hours. If precipitation falls on the newly coated concrete before the film has dried sufficiently to resist damage, or if the film is damaged in any other way, apply an additional coat of curing compound at the original specified rate. Do not apply curing compound to concrete surfaces that will receive a subsequent concrete placement. Remove curing compound from concrete surfaces that will receive a subsequent concrete placement.
2.Wet Burlap and White Polyethylene Sheeting. Pre-soak burlap strips for at least 24 hours before placing. Cover the concrete with strips of wet burlap at least 4 feet longer than the width of the slab to cover the sides. Lay the strips across the slab and overlap at least 1/2 the width of the strip to provide a double thickness of burlap. Ensure that the burlap remains wet throughout the specified curing period. Ensure that the wet burlap does not add excess water to the concrete surface. Cover the wet burlap with white polyethylene sheeting. Overlap sections of polyethylene sheeting at least 18 inches. Place the white polyethylene sheeting and weigh down to ensure that it remains in contact with the surface. Where reinforcement steel protrudes, ensure that the white polyethylene sheeting is draped, and overlapped over the structure to protect any exposed areas. Extend white polyethylene sheeting 4 feet beyond the edges of the concrete. Replace or restore polyethylene sheeting that is damaged or disturbed.
3.White Polyethylene Sheeting. Overlap sections of polyethylene sheeting at least 18 inches. Place the polyethylene sheeting and wei gh down to ensure that it remains in contact with the surface. Where reinforcement steel protrudes, ensure that the polyethylene sheeting is draped and overlapped over the structure to protect any exposed areas. Extend the polyethylene sheeting 4 feet beyond the edges of the concrete. Replace or restore polyethylene sheeting that is damaged or disturbed. Maintain curing materials for arches and culverts for at least 7 days; for other concrete placements, maintain for at least 3 days. When using protecti ve measures for cold weather concreting, as specified in 504.03.02.C.1 maintain the curing materials until the protective measures are removed.
G.Removal of Forms and Falsework. The Department may require concrete strength tests as specified in the Special Provisions for removal of forms and falsework. Remove forms without damaging the surface. The Contractor may remove forms 24 hours after placing concrete, except for the following:
1.Remove barrier curb and parapet forms as soon as the concrete holds its shape to facilitate finishing.
2.When using concrete that contains more than 20 percent fly a sh by weight of total cementitious material, maintain the forms for at least 3 days.
3.The Contractor may remove forms for wing walls after 3 days if the concrete has attained a strength of 3,000 pounds per square inch as determined from 2 concrete cylinders field cured according to AASHTO T 23. If concrete cylinders for wing walls are not tested, or do not meet a strength 3,000 pounds per square inch when tested before 14 days, the Contractor may not remove forms until 14 days after the concrete has been placed.
4.The Contractor may remove forms for battered columns or pier caps after 3 days if the concrete has attained a strength of 4 ,000 pounds per square inch as determined from 2 concrete cylinders field cured according to AASHTO T 23. If concrete cylinders for battered columns or pier caps are not tested, or do not meet a strength 4,000 pounds per square inch when tested before 14 days, the Contractor may not remove forms until 14 days after the concrete has been placed.
5.The Contractor may remove forms for arches or culverts after 7 days if the concrete has attained a strength of 4,000 pounds per square inch as determined from 2 concrete cylinders field cured according to AASHTO T 23. If concrete cylinders for arches or culverts are not tested, or do not meet a strength of 4,000 pounds per square inch when tested before 14 days, the Contractor may not remove forms until 14 days after the concrete has been placed. Do not remove falsework and centering for spandrel -filled arches before the abutments have been placed up to the spring line.
6.Do not remove falsework supporting the deck of rigid frame structures until the embankment has been placed behind the vertical legs.
7.When using protective measures for cold weather concreting, as specified in 504.03.02.C.1, do not remove the forms until the protective measures are removed regardless of concrete cylinder strength.
8.Do not remove the forms for decks for 14 days. For elevated formwo rk, lower centering gradually to prevent damage to the structure. Remove falsework from continuous or cantilevered structures to ensure that the structure is gradually subjected to its working stress.
H.Finishing Concrete Surface. Finish the surface of the concrete immediately after removing the forms. Apply a Class 1 finish to surfaces not exposed to view. Apply a Class 2 finish to all surfaces exposed to view. Do not begin finishing a surface until the entire face of the structure is completed to ensure a uniform texture and color. For barrier curb and parapet, apply a Class 2 finish within 48 hours of placing concrete. The classes of concrete finish are as follows:
1.Class 1, Surface Finish. Remove projecting wire or metal devices that have been used for holding the forms in place. If the wire or metal device cannot be removed, cut the wire or metal device at least 1 inch below the surface of the concrete. Remove lips of mortar and irregularities caused by form joints. Ensure that all construction and expansion joints are tooled and free of mortar and concrete. Patch holes, de pressions, voids, and honeycombs by chipping away coarse or broken material until a dense uniform surface of concrete exposing solid coarse aggregate is obtained. Cut away feathered edges to form faces perpendicular to the surface. Saturate the surfaces of the deficient area with water, then fill the deficient area with stiff mortar. Finish the surface of the mortar with a wooden float before initial set takes place. When patching large or deep areas as determined by the RE, patch the area using the same mix design concrete as the surrounding concrete. Chip away coarse or broken material until a dense uniform surface of concrete exposing solid coarse aggregate is obtained. Cut away feathered edges to form faces perpendicular to the surface. Saturate the surface of the area with water, then apply a layer of bonding compound to the area. Fill the area with the concrete. Finish the surface of the concrete with a wooden float before initial set takes place. The Department may reject a structure for having areas of excessive honeycombs as directed by the RE.
2.Class 2, Rubbed Finish. After performing a Class 1 finish, rub surfaces with a wetted wooden block or a medium coarse carborundum stone, using a small amount of mortar on its face. Do not use the carborundum stone until the concrete has hardened to the state where the sand grinds rather than ravels or rolls. Continue rubbing until form marks, projections, and irr egularities have been removed, voids are filled, and a uniform surface has been obtained. Leave the paste produced by this rubbing in place. After the entire surface of the structure has been rubbed and the paste has dried, obtain the final finish by rub bing with a fine carborundum stone and water until the entire surface is of a smooth texture and uniform color.
I.Protecting Concrete Structures. Post warning tape around flatwork such as bridge decks, pavement, sid ewalks, driveways, and islands during the curing period. Provide wet burlap or polyethylene sheeting to protect the edges and surface of the plastic concrete from precipitation. Do not drive piles within 200 feet of concrete that is being placed or has be en placed within the previous 24 hours unless approved by the RE. Ensure that salt or brackish water does not come in contact with the concrete for a period of 28 days after being placed.
J.Loading Concrete Structures. Do not allow anything other than the curing materi als on concrete surfaces for 24 hours after placing the concrete. The Contractor may begin constructing forms for subsequent concrete placements after the forms from the underlying concrete can be removed as specified in 504.03.02.G. After the forms have been constructed and at least 3 days after the underlying concrete has been placed, the Contractor may perform subsequent concrete placements. The Contractor may begin storing materials, backfilling, or other loading on the concrete surface 3 days after the concrete has been placed if the forms can be removed as specified in 504.03.02.G.
504.03.03 Epoxy Waterproofing
Provide a copy of the manufacturer’s recommendations to the RE at least 5 days before applying epoxy waterpr oofing. Apply epoxy waterproofing to abutment and pier seats after applying the finish and at least 3 days after stripping the forms, and to the tops of slabs of culverts having less than 2 feet of fill and an HMA overlay directly over that slab. Do not apply epoxy waterproofing to riding surfaces. Immediately before application, clean the surfaces of dirt, grease, form oil, or other foreign material that may have accumulated. Do not apply epoxy waterproofing unless the ambient temperature is between 40 and 85 °F at the time of application. Mix and apply the epoxy waterproofing according to the manufacturer’s recommendations. If necessary, bushhammer bearing surfaces to their proper elevations before applying the epoxy waterproofing. Apply 2 coats of epoxy waterproofing using a brush or roller. Allow the first coat to dry before applying the second coat. Ensure that the total thickness of the coatings is 10 mils. While the second coat is still tacky, broadcast grit at uniform rate of 5 pounds per squa re yard over the top surfaces by hand, except on masonry plate bearing areas. After the epoxy waterproofing has set, brush off excess grit and dispose of as specified in 201.03.01.H. Allow the epoxy waterproofing to completely dry before placing any material against the concrete member.
504.03.04 Concrete Staining
Prior to staining, examine the surfaces to be stained. Bring areas requiring patching or repair to the attention of the RE.
A.Submittals. Submit product information and manufacturer color chip sample for approval by the Office of Landscape Architecture.
B.Cleaning. After the concrete areas and any patching has cured for at least 28 days, power wash all surfaces for initial preparation at a minimum pressure of 2,500 psi using a 25 degree tip and a standoff distance of 2 feet. Verify that all foreign materials, such as dirt, dust and form oil, have been removed and surfaces are clean prior to application of primer and stain. If contaminants are still present after initial preparation, vary power washing parameters or use other suitable methods to clean surfaces.
C.Test Staining. Complete a test staining program fo r porosity, adhesion, and color acceptance before staining operations on approved textural mock-ups or in place according to contract plans. Test area(s) to include both smooth and textured concrete sections. Prepare test area for initial surface prepara tion as described in 504.03.04.B for inspection by the RE. If the staining mock-ups are approved, they may be included as part of the final construction.
Referenced in this section
Structural Concrete in other states
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Source: Standard Specifications for Road and Bridge Construction, 2019 (rev. 2022-12-21) Edition. Pages 265–272 of 651. View official source ↗