238 ALASKA 2020 SECTION 510
510-1.01 DESCRIPTION . Remove, wholly or in part, and satisfactory dispose of bridge deck
concrete to the depth and limits shown on the Plans and/or as directed. Remove all unsound (spalled, cracked and/or delaminated) concrete.
510-2.01 MATERIALS. Use falsework meeting Section 512.
CONSTRUCTION REQUIREMENTS
510-3.01 GENERAL. Perform work to meet the applicable requirements of Section 202.
Prevent damage to reinforcing steel designated to remain in place. Following the concrete removal, the Engineer will inspect any exposed reinforcing steel. Remove and replace bars or sections of bars that are damaged or deteriorated at any point to less than 80 percent of their original cross section, including cracked or broken bars. Remove sufficient concrete to allow for splicing of a new piece of reinforcing steel. Extend the spliced reinforcing steel 32 inches beyond each end of the damage or deterioration. Replace damaged or deteriorated steel reinforcing bars under Subsection 109- 1.05, if:
1.not damaged by Contractor operations, or
2.damage from milling is a result of the concrete cover being 1 inch or less.
510-3.02 METHOD OF R EMOVAL. Remove concrete to specified depth using hydrodemolition
equipment. For areas of the deck not accessible to hydrodemolition, use mechanical impact methods. You may use power operated rotary milling machines to scarify the upper deck to a nominal depth of 3/4 inch.
510-3.03 MILLING. Use rotary type milling machines, capable of scarifying a minimum width of 4
feet per pass.
510-3.04 Hydrodemoli Tion.
1.Equipment. Use high -pressure water pumping system, low -pressure water filtration and feed systems, and remote- control stations for two remote- controlled demolishing units. Ensure a nozzle pressure of 25,000 psi. Employ qualified personnel, certified by the equipment manufacturer, to operate the equipment. Submit operator certification(s) to the Engineer for approval before beginning concrete removal operation.
2.Concrete Removal. Perform concrete deck removal as shown on the Plans. Perform hydrodemolition removal resulting in a rough finished surface, free of debris. Before concrete removal begins, the Engineer will select a trial area of sound concrete of the deck approximately 30 ft2 in size. Advance the demolishing unit over this area and establish the operati ng parameters to achieve the depth of removal called for on the Plans. Submit a list of operating parameters to be used for production work to the Engineer for approval. During production work, the Engineer may require recalibration of the equipment if, i n the Engineer’s opinion, satisfactory concrete removal is not being obtained. Remove debris immediately after demolition operation to prevent rebonding to the surface of sound concrete. Remove any material which is allowed to rebond without extra compens ation 239 ALASKA 2020 and with no contract time extension. Avoid damage to remaining sound concrete and reinforcing steel. Furnish and erect rigid safety shields adjacent to hydrodemolition equipment, or otherwise protect adjacent traffic and property from flying debris. Protect traffic from hazardous glare of work lights during nighttime operations. Furnish water to operate the hydrodemolition equipment.
3.Controlling Wastewater and Debris . Submit a work plan no less than 5 working days prior to the preconstruction conference describing environmental protection and procedures including BMPs for hazardous and non- hazardous waste, including but not limited to testing, handling, treatment, temporary storage, transportation, and disposal according to federal, state, and local re quirements. The plan must be stamped by an Engineer registered in the State of Alaska and must be acceptable to the Alaska Department of Environmental Conservation. Perform the following:
a.Capture and contain all wastewater and debris within the work area.
b.Filter wastewater to ensure that it is free of concrete particles and sediment before being discharged.
4.Reinforcing Steel. Clean all reinforcing steel that is to remain in place and has been exposed by removal operations. Remove all rust and corrosive products immediately prior to concrete placement. Remove oil, dirt, concrete fragments, laitance, loose scale, and other coating that would destroy or inhibit the bond with the new concrete. Protect cleaned reinforcing steel from the elements and from contami nation. Sandblast reinforcing steel contaminated as a result of your failure to provide adequate protection, at your expense.
510-3.05 MECHANICAL METHODS. In areas not accessible to hydrodemolition remove concrete
by mechanical impact methods to the same depth as adjacent areas. Avoid damage to sound concrete structures by the improper use of mechanical tools. Repair, cracked or damaged structures, as required. Also use mechanical methods if either of the following conditions exists:
1.There is unsound concrete remaining after the hydrodemolition is done in an area
2.There is a lack of bond between the existing concrete and the reinforcing steel If unsound concrete exists or if the bond is broken around existing reinforcing steel, remove concrete to provide a 3/ 4 inch minimum clearance around the reinforcing steel. Do not damage any of the existing reinforcing steel that is to remain in place. Operate the mechanical impact tool at angles less than 45 degrees as measured from the deck surface to the tool. Do not use jack hammers heavier than the nominal 30 lb class or chipping hammers heavier than the nominal 15 lb class.
510-3.06 CLEANUP. Following concrete removal, clean the job site and remove debris. Dispose
of debris at a Department of Environmental Conservati on approved landfill. Remove dust and loose particles by flushing with water and/or vacuum cleaning.
510-4.01 METHOD OF M EASUREMENT. See Section 109, by the area of removed surface,
regardless of the depth of removal. 240 ALASKA 2020 510-5.01 BASIS OF PA YMENT. The contrac t price includes full compensation for containment structures, debris collection systems, wastewater filtration systems, disposal of debris, and incidentals required to complete the work. Removal and disposal of incidental items such as deck drains or dowels, repair of electrical conduits, replacement of electrical conduit expansion fittings, removal and reinstallation of pipe hangers, and removal and reinstallation of light fixtures or illuminated signs, are subsidiary. Payment for falsework is covered under Section 512. Payment will be made under: PAY ITEM Item Number Item Description Unit 510.0001.____ Removal of Concrete Bridge Deck SF 241 ALASKA 2020 SECTION 511 MECHANICALLY STABILI ZED EARTH (MSE) WALL
511-1.01 DESCRIPTION . Furnish and install mechanically stabi lized earth wall.
511-2.01 MATERIALS. Meet the following:
Class A Concrete Section 501 Precast and Cast -in-Place Concrete Panels Section 501 Reinforcing Steel Section 503 Structural Steel AASHTO M 270 Pipe and Perforated Pipe Section 706 Geotextile for Drainage Subsection 729- 2.02 Geogrid Subsection 729- 2.05 Geocomposite Drainage System As Specified Porous Backfill Material Subsection 703- 2.10
1.Structure Backfill and Foundation Fill . Meet Subsection 703- 2.07, Selected Material, Type A. Use materials wi th a sodium sulfate soundness loss less than 30 percent after four cycles as determined by AASHTO T 104 and free of shale or other particles of low durability. When using backfill material with 80 percent passing the 3/4 inch sieve, the minimum angle of in ternal friction on the portion of the material finer than the No. 10 sieve must be 34 degrees, as tested by AASHTO T 236. When using steel soil reinforcement, use backfill material meeting the following electrochemical requirements:
a.pH of 5 to 10 (AASHTO T 289)
b.Resistivity not less than 30 ohmmeters (AASHTO T 288)
c.Chlorides not greater than 100 ppm (AASHTO T 291)
d.Sulfates not greater than 200 ppm (AASHTO T 290)
2.Wall Members . Provide facing consisting of precast concrete panels, modular units, cast -in- place concrete, or welded wire fabric, as specified. Manufacture concrete panels with a minimum concrete compressive strength of 4,000 psi. Finish the exposed face with ordinary finish. For the face not exposed to view, provide a uniform surface finish free of open pockets of aggregate or surface distortions in excess of 1/4 inch. Locate soil reinforcement connection hardware during concrete placement to avoid contact with the panel reinforcing steel. Shop- fabricate welded wire fabric reinforcement from cold-drawn wire meeting AASHTO M 32, and the finished fabric meeting AASHTO M 55.
3.Soil Reinforcement . Use approved geogrid reinforcement. Galvanize all steel soil reinforcement and any steel connection hardware to meet AASHTO M 111. Manufacture steel strip reinfor cement by hot rolling to meet ASTM A572, Grade 450, or approved alternate.
4.Working Drawings . Submit all working drawings and design calculations, including:
a.Earthwork requirements including specifications for material and compaction of backfill.
b.Details of revisions or additions to drainage systems or other facilities required to accommodate the system.
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 266–268 of 584.