604Payment will be made under: ————————————————————————— Pay Item Pay Unit————————————————————————— Furnish Asphalt Plug Joint Cubic Foot Place Asphalt Plug Joint Linear Foot————————————————————————— SECTION 425—RIGID CONCRETE BRIDGE DECK OVERLAYS
425.01 Description
This work shall consist of preparing bridge deck surfaces, and furnishing and placing rigid concrete overlays on concrete bridge decks. The Department will specify the overlay material to be used and the overlay depth on the Plans or elsewhere in the Contract.
425.02 Materials
Silica fume concrete, latex-modified concrete, high early strength latex modified concrete, and very- early-strength latex-modified concrete shall conform to Section 217, except that the coarse aggregate shall be size No. 7, No. 8, or No. 78 for depths and steel clearances less than or equal to 2 inches, and size No. 57, No. 7, No. 8, or No. 78 for depths greater than 2 inches. The use of fly ash or slag will be permitted in silica fume concrete. Class A4 Bridge Deck Concrete used in deep overlays shall conform to Section 217 for Class A4 Concrete, Modified to Minimize Cracking with Shrinkage Reducing Admixture.
425.03 Procedures
a.Deck Surface Preparation: Preparation of a reinforced concrete deck will require one or more of the following operations: removal of asphalt concrete overlay, Type A milling, and/or Type A or B hydro-demolition, as follow.
1.Removing Asphalt Concrete Overlay: The Contractor shall remove the asphalt wearing surface (where applicable) from bridge decks and approach slabs in a manner such that underlying sound concrete will not be damaged and can be prepared to receive necessary treatment. The Contractor shall dispose of the removed asphalt material in a manner approved by the Engineer. Sound concrete damaged as a result of the Contractor’ s operations shall be repaired in accor - dance with Section 412 at the Contractor’ s expense. The Contractor shall not allow fuel oils or other materials that will prevent bonding of the overlay to remaining sound concrete to come into contact with the prepared surface.
2.Type A milling shall consist of milling the surface of the bridge deck and concrete approaches to the depth specified. Equipment shall be capable of removing hydraulic cement concrete material to the require depth resulting in a reasonably uniform surface without damaging adjacent areas or the remaining material. Milling equipment shall be capable of removing at least 1/2 inch of existing material per 424.04 605pass. The Contractor shall use power-driven hand tools to remove concrete on vertical surfaces of curbs, parapets, unsound concrete around reinforcing steel, and in confined areas.
3.Hydro-demolition: The Contractor shall perform hydro-demolition in accordance with the hydro-demolition equipment manufacturer’ s instructions, this Section, and as directed by the Engineer. Any bituminous patches shall be removed and the debris cleaned from the deck prior to the commencement of hydro-demolition operations. Patches may be removed using localized hydro-demolition or milling, hand tools, or pneumatic hammers. The Contractor shall exercise caution during concrete removal operations to prevent damaging or cutting the reinforcing steel. Heavy equipment shall not be allowed in areas where the reinforcing steel is unsupported, unless otherwise approved by the Engineer. Any bars damaged as a result of the hydro-demolition operations shall be repaired or if necessary replaced in accordance with Section 412.03 at no additional cost to the Department. Reinforcing steel shall be replaced in-kind, matching existing steel bar sizes, unless otherwise directed or approved by the Engineer. Any reinforcing steel that is left unsupported after the hydrodemolition operations shall be adequately tied and supported as soon as practical before beginning overlay operations. The Plans or other Contract documents will specify one of the following types of hydrodem - olition:
a.Type A Hydro-demolition - Type A Hydro-demolition shall consist of removing concrete to a depth of 1/2 inch below the milled surface of hydraulic cement concrete decks in areas of sound concrete, and removing concrete to a depth of 1 inch below the bottom of the top mat of reinforcing steel in areas of deteriorated concrete (e.g., spalls or delamina - tions at or below top mat reinforcement). In areas where the reinforcing steel is partially exposed for fifty (50) percent or less of the perimeter of the bar, concrete removal is not required if the concrete is sound.
b.Type B Hydro-demolition - Type B Hydro-demolition shall consist of removing concrete to a depth of 1 inch below the bottom of the top mat of reinforcing steel over the entire surface of the deck.
c.Work plan - Prior to beginning the work, the Contractor shall submit a hydrodemolition work plan to the Engineer for approval. This work plan shall include complete details of the following items:
1.The means of controlling runoff water. The Contractor shall prevent the runoff water from flowing onto lanes of traffic adjacent to or below the work and into any body of water. The Contractor shall be responsible for compliance with all environmental laws and regulations regarding the discharge of runoff water. The Contractor shall provide specific details of the method of runoff water treatment and collection, and shall obtain all necessary permits required for its legal disposal or discharge into the environment.
2.The method of safety shielding to prevent overspray into traffic. Shielding shall be installed as necessary to ensure the containment of all dislodged concrete and debris 425.03 606in order to protect workers and the traveling public from flying debris both under and on the work site.
3.The method for handling expected and unexpected blow-through of the deck. This method shall provide for containment of runoff water, debris, Type B coatings (as described in Section 411), and the protection of the area under the bridge deck. If an unexpected blow-through occurs, the Contractor shall immediately stop the hydro-demolition equipment and implement containment and protection procedures if these are not already in place. The Contractor shall ensure the equipment is correctly calibrated prior to restarting the hydro-demolition operation. The Engineer may require the Contractor to recalibrate the equipment at no additional cost to the Department if multiple unexpected blow-throughs occur.
d.Equipment - Hydro-demolition equipment shall be a computerized, self propelled machine that utilizes a high pressure water jet stream to provide a rough and bondable surface while removing all unsound concrete, rust, and concrete particles from exposed reinforce - ment during the initial pass. Hydro-demolition equipment shall consist of a water supply system, high-pressure water pumping system, and a demolition unit. The demolition unit shall be fully automated and provide precise control of the water jet(s) to facilitate a thorough and consistent removal operation. If required, the hydro-demolition equipment shall be capable of removing concrete from around and below the reinforcing steel. Such removal may require several passes of the equipment; however, payment shall be based on the square yards of deck surface at the depth of removal specified on the plans regardless of the number of passes necessary to achieve the depth specified. The hydro-demolition equipment shall clean all exposed reinforcing steel of rust, concrete fragments, laitance, loose scale, and other coatings that may inhibit or prevent bonding with the new concrete. Reinforcing steel not thoroughly cleaned during hydro-demolition concrete removal shall carefully be hand-tool cleaned. The Contractor shall maintain an adequate supply of wear items, repair parts, and service personnel onsite to insure that the hydro-demolition operations will not be interrupted for more than 24 consecutive hours in the event of breakdown or malfunction. No contract time adjustment due to delays associated with repairs or obtaining replacement equipment will be considered.
e.Personnel - Qualified personnel certified by the equipment manufacturer shall operate the hydro-demolition equipment. Operator certification shall be submitted to the Engineer for review prior to beginning the hydro-demolition operations. The Contractor shall supply the water and all other materials necessary to do the specified work. The Contractor shall dispose of all removed concrete and other debris in accordance with Section 106.04.
f.Test area - The Engineer will designate a trial area where the Contractor shall demonstrate that the equipment, personnel, and method of operation are capable of producing results satisfactory to the Engineer. The trial area shall consist of two patches, each approximately 50 square feet. The first trial patch shall consist of sound concrete as determined by the Engineer. The second trial patch shall consist of deteriorated concrete as determined by the Engineer. 425.03 607 (1) Test Area for Type A Hydro-demolition - The hydro-demolition equipment shall first be calibrated on the sound trail patch to remove concrete to a depth of 1/2 inch. The hydro-demolition equipment shall then be used to remove concrete from the deteriorated trial patch using the operating parameters established from the sound trial patch. If all the deteriorated concrete is removed as determined by the Engineer, the hydro-demolition equipment will be considered as calibrated. If all deteriorated concrete is not removed as determined by the Engineer, the process shall be repeated until satisfactory results are obtained. The operating parameters from the successful tests shall be used as the basis for the production removal.
2.Test Area for Type B Hydro-demolition - The hydro-demolition equipment shall first be calibrated on the sound trial patch to remove concrete to a depth of 1 inch below the bottom of the top mat of reinforcing steel. The hydro-demolition equipment shall then be used to remove concrete from the deteriorated trial patch using the operating parameters established from the sound trial patch. If all the deteriorated concrete is removed as determined by the Engineer, the hydro-demolition equipment will be considered as calibrated. If all deteriorated concrete is not removed as determined by the Engineer, the process shall be repeated until satisfactory results are obtained. The operating parameters from the successful tests shall be used as the basis for the production removal. The Contractor shall record the calibrated hydro-demolition equipment’ s operating parameters and provide the Engineer with a copy. The record shall include at least the following information: • Water pressure (gauge) • Machine staging control (step) • Nozzle size • Nozzle travel speed The Contractor shall monitor and periodically adjust equipment to meet the level of removal demonstrated during the initial calibration process. Any changes in operating parameters that result from post-calibration monitoring must be approved by the Engineer. In lieu of this method of calibration, the hydro-demolition equipment manufacturer’ s representative may propose an alternate method of calibration the representative believes more suited to the work. Any proposed alternate calibration method shall be subject to the Engineer’ s approval. After hydro-demolition operations, the Contractor shall clean up all debris before it dries on the deck. Clean-up operations shall directly follow the hydro-demolition process to prevent the debris from resettling or reattaching itself to the surface of the sound concrete. Should the hydro-demolition debris dry on the surface of the sound concrete or reinforcing steel, the Contractor shall clean the concrete, reinforcing steel or other surfaces to the Engineer’ s satisfaction at no additional cost to the Department. Immediately after hydro-demolition and clean-up operations, the Contractor shall sound the deck in the presence of the Engineer and remove any remaining loose and unsound 425.03 608concrete as approved by the Engineer. Loose and unsound concrete shall be removed to a depth of 1 inch below the bottom of the top mat of reinforcing steel but not more than 2 1/2 inches below the top mat of reinforcing steel. If hydro-demolition operations are consistently exposing the bottom mat of steel, the Contractor shall review the Contractor’ s procedures, including machine settings and make required adjustments. If required, a hand-held hydro-demolition wand or 30 lb. pneumatic hammer(s) may be used to perform additional removal. Areas of blowthrough to receive full-depth deck repair shall be squared-up and additional concrete removed to obtain a minimum edge thickness of 1 1/2 inches of sound concrete at the bottom of the deck. Areas of full-depth deck repair will be measured and paid for as Type C Patching. If the concrete overlay is placed within 48 hours of the hydro-demolition operation, additional cleaning of the exposed steel reinforcement will not be required for deck areas treated by hydro-demolition. Additional cleaning of the exposed steel reinforcement and concrete deck surface by abrasive blasting or high-pressure water blasting shall be performed if steel reinforcement and/or concrete deck surface is exposed for longer than 48 hours prior to placing the concrete overlay. Deck areas prepared by processes other than hydro-demolition shall also be cleaned by abrasive blasting or high-pressure water blasting when exposed for longer than 48 hours prior to placing the concrete overlay. The final prepared surface shall be free of dirt, oil, concrete fragments, abrasive blast residue, standing water, or any other deleterious material that may adversely affect the bond of the overlay. If the Contractor uses compressed air, it shall be oil-free. Any areas of the prepared deck surface contaminated with oil, grease or other materials detrimental to good bonding of the concrete as a result of the Contractor’ s operations shall be removed to such depth as is necessary to achieve satisfactory bond as determined by the Engineer. Cleaning and removal necessitated by contamination caused by the Contractor’ s operations shall be performed at no additional cost to the Department.
b.Overlays The Contractor shall place construction joints as necessary in rigid concrete overlays that are not detailed on the plans as directed or approved by the Engineer. Construction joints in rigid concrete overlays shall be sealed in accordance with the requirements for Crack Repair, Type A as detailed in Section 412.03(b)5a. The standard methods of preparation and placement of a rigid overlay are as follows:
1.Type A Milling to a depth of 1/2 inch and placement of a silica fume or latex modified concrete overlay as specified on the Plans or elsewhere in the Contract. Prior to placement of the overlay, a portion of the latex or silica fume concrete shall be brushed onto the prepared surface. Care shall be taken to ensure that both vertical and horizontal surfaces receive a thorough even coating and that the rate of progress is limited so that the brushed material does not become dry before it is covered with additional material and brought to final grade. Excess coarse aggregate remaining after brushing shall be removed. When Type A Milling to a depth of 1/2 inch and placement of an overlay are specified, the Contractor may use a combination of Type A Milling and\or Type A Hydro-demolition with the Engineer’ s written approval to prepare the deck provided both operations are performed at no additional cost to the Department.425.03 609 2. Type A Milling to the depth specified, or to the depth called for in the Contractor’ s Plan of Operations, as approved by the Engineer, followed by Type A Hydro-demolition, and place - ment of a silica fume or latex-modified concrete overlay. Prior to milling, the Contractor shall evaluate the concrete cover over the existing reinforcing steel and adjust the depth of milling to prevent damage to the reinforcing steel. Reinforcing steel damaged as a result of the Contractor’ s operations shall be repaired or replaced in accor - dance with Section 412.03 at no additional cost to the Department. Reinforcing steel shall be replaced in-kind, matching the bar sizes of existing steel, unless otherwise directed or approved by the Engineer. After concrete removal, a silica fume or latex modified concrete overlays shall be placed as specified on the plans. Brushing portion of concrete overlay onto prepared surface is not required when the surface is prepared by Type A Milling to the specified depth followed by Type A hydro-demolition.
3.Type B Hydro-demolition and placement of a Class A4 Bridge Deck Concrete Overlay Type B Hydro-demolition shall be performed in accordance with the requirements herein and a deep overlay shall be constructed using Class A4 Bridge Deck Concrete Modified to Minimize Cracking with Shrinkage Reducing Admixture. The deep overlay shall be constructed to the depth indicated on the Plans or elsewhere in the Contract in accordance with Section 404. When Type B Hydro-demolition is specified, the Contractor shall, when approved by the Engineer in writing, have the option of using Type A Milling to remove the concrete to within 1/2 inch of the top mat of reinforcing steel with the remainder of the concrete removal performed by Hydro-demolition. Overlay concrete shall be placed within the range of depth specified in the Contract or directed by the Engineer, and verified by the Engineer during placement operations. Overlays shall not be placed until deck repair concrete has attained 90 percent of the minimum design compressive strength. Vehicular traffic will not be permitted on the bridge until the overlay has attained a compressive strength of 3,500 pounds per square inch. Expansion joints and dams shall be maintained through the overlay. A bulkhead equal in thickness to the width of the joint shall be installed to the required grade and profile prior to concrete placement. A construction dam or bulkhead shall be installed in the case of a major delay in placement operations. During minor delays of 1 hour or less, the end of the placement shall be protected from drying. The Contractor shall shot-blast the entire milled surface to be overlaid, the edge of the previously placed overlay, and an area of the face of the curb no less than the thickness of the overlay within twenty-four (24) hours of the beginning of the overlay operations. Where applicable, this shall include the widened portion of bridge decks that are specified to be overlaid with latex-modified or silica fume concrete. For at least 1 hour prior to placement of overlay concrete, the surface shall be continuously and thoroughly water soaked. After soaking, the surface shall be covered with plastic sheeting to prevent 425.03 610loss of moisture and to keep the surfaces clean. Puddles of standing water shall be removed before the overlay is placed. The overlay shall be placed only when the ambient air temperature is 50 degrees F and rising. At temperatures above 85 degrees F , the Engineer may require placement to be made at night or during early morning hours if a satisfactory surface finish is not being achieved. Mixers for latex-modified concrete shall be batch mixers or automatic mobile continuous mixers conforming to Section 217. The mixing capacity shall be such that placing and finishing operations can proceed at a uniform rate, with final finishing completed before formation of the plastic surface film. A yield test shall be performed by the Contractor prior to deck placement for each mixing unit, when each unit is moved from the job site for recharging, when the source of stockpiled materials is changed, or when there is reason to believe that the calibration may be erroneous. Mixers for silica fume concrete shall be truck mixers conforming to Section 217. The amount mixed shall be such that the placing and finishing operations can proceed at a uniform rate. The silica fume concrete shall be uniform in composition and consistency when discharged from the mixer. The overlay shall have a thickness of at least 1 1/4 inches of latex-modified or silica fume concrete. At the Contractor’ s option, latex-modified or silica fume concrete may be used in lieu of hydraulic cement concrete as required for Type A, B, or C patching or joint and crack repairs, and such material shall be placed monolithically with the overlay. If the rate of evaporation of surface moisture from the latex-modified or the silica fume concrete exceeds 0.05 pound per square foot per hour during placement, measures shall be taken to reduce the rate of evaporation, such as by fogging. Moist-curing – The surface shall be protected from prematurely drying or cracking by prompt application of wet burlap. Care shall be taken to ensure that the burlap is well drained and that it is placed as soon as possible, but no later than 15 minutes after screeding to ensure that the surface is wet at all times during curing. The burlap and surface of the concrete shall be maintained in a continuously moist condition during the initial curing period. Unless otherwise specified in the Contract or directed by the Engineer the curing periods shall be as follows: The initial moist curing periods for latex modified concrete and high early strength latex modified concrete overlays shall be 48 hours followed by an additional 48 hours of air curing before opening to traffic. Overlays of very-early strength latex-modified concrete shall be moist cured from the time they are placed until they can be opened to traffic. The initial moist curing period for silica fume concrete shall be 72 hours, unless otherwise specified or directed by the Engineer, followed by the immediate application of a liquid membrane-forming curing compound conforming to Section 220. The curing compound shall be completely dry before opening the overlay to traffic.
425.04 Measurement and Payment
Remove asphalt concrete overlay will be measured in square yards of surface area and will be paid for at the contract unit price per square yard. This price shall include removing, handling, and disposing of waste.425.03 611Type A milling will be measured in square yards of surface area and will be paid for at the contract unit price per square yard for the depth specified. This price shall include performing milling, handling, and disposing of waste, replacing any damaged reinforcing steel, and determining steel cover to avoid damaging steel. (Type) Hydro-demolition will be measured in square yards for the depth specified and will be paid for at the contract unit price per square yard. This price shall include preparing a work plan and containment system; shielding protection; test patches for and calibration of the hydro-demolition equipment and recalibration (if necessary); removing and disposing of all unsound and loose concrete; sounding the deck after hydro-demolition; removing any additional concrete necessary after sounding; cleaning reinforcing steel; replacing any damaged reinforcing steel; collecting, filtering, and disposing of waste water in accordance with all applicable environmental laws and regulations; any required environmental permits and documentation to comply with such laws and regulations. Furnish silica fume concrete, latex modified concrete, high early strength latex modified concrete, very-early-strength latex-modified concrete, or Class A4 bridge deck concrete will be measured in cubic yards and will be paid for at the contract unit price per cubic yard. Measurement for overlay concrete produced by batch mixers will be determined by truck tickets, assuming a 95 percent yield or, when produced by automatic mobile mixers, measurement will be by metered ticket. Reduction in the quantity of overlay concrete eligible for payment will be made for any volume of waste. This price shall include producing the mixture, all handling, delivering to the work site, and trial batching. Additional concrete beyond the depth range of the pay item that is requested to address cross slope and other surface irregularities and rideability issues shall be at the direction of the Engineer. Only those volumes of additional concrete that are approved by the Engineer prior to placement of the overlay will be considered for payment. Place silica fume concrete, latex modified concrete, high early strength latex modified concrete, very-early-strength latex-modified concrete, or Class A4 bridge deck concrete overlay will be measured in square yards and will be paid for at the contract unit price per square yard on a plan quantity basis. This price shall include preparing the surface, placing, handling, finishing, and curing the concrete. No additional compensation will be made for placing concrete beyond the depth range specified. Payment will be made under: ————————————————————————————Pay Item Pay Unit———————————————————————————— Remove asphalt concrete overlay Square yard Type A milling (Depth) Square yard (Type) Hydro-demolition (Depth) Square yard Furnish (Type) concrete (Depth Range) Cubic yard Place (Type) concrete overlay Square yard———————————————————————————— SECTION 426—REP AIRING EXISTING STEEL STRUCTURES
426.01 Description
This work shall consist of repairing existing steel structures in accordance with these specifications and in conformity with the details shown on the plans or established by the Engineer.426.01
Source: Virginia Road and Bridge Specifications, 2020 Edition. Pages 632–638 of 1,065.