237 ALASKA 2020 SECTION 509 MICROSILICA MODIFIED CONCRETE OVERLAY [ RESERVED ] 238 ALASKA 2020 SECTION 510 REMOVAL OF CONCRETE BRIDGE DECK
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
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 265–265 of 584.