Division 7 Supplemental - Hydrodemolition and Bridge Deck Overlay Construction Inspection
HYDRODEMOLITION AND BRIDGE DECK OVERLAY CONSTRUCTION INSPECTION
This document clarifies the procedures for hydrodemolition and bridge deck overlay construction inspection. It also provides requirements for sampling and testing of bridge deck overlay concrete, documenting bridge steel reinforcement, and documentation for bridge deck overlay construction inspection. This document must be coordinated with the MDOT Standard Specifications for Construction, Divisions 6 and 7 of the Construction Manual, and the Materials Quality Assurance Procedures Manual.
Documentation for Hydrodemolition Inspection
The contractor shall submit a hydrodemolition pH control plan for review and acceptance prior to beginning any hydrodemolition work according to the Special Provision for Managing Hydrodemolition Runoff Water, as listed in the proposal. Attached is an “MDOT Hydrodemolition Projects pH Control Plan Checklist” and a “Sample Hydrodemolition Control Plan” for additional guidance. The Groundwater Discharge General Permit, 2215-05-7 is available on the Michigan Department of Environment, Great Lakes, and Energy (EGLE)Web site here
Calibrate the hydrodemolition equipment as listed in Section 712 of the Construction Manual. Record the settings (water pressure, cutting head speed, and forward advancement) on the Inspector’s Daily Report, Form 1122B.
Ensure the contractor is completing the hydrodemolition log per the special provision. You can locate the pH control plan checklist and the Sample Hydro Control plan here.
Documentation for Bridge Deck Overlay Construction Inspection
The resident/project/delivery engineer (hereinafter referred to as “engineer”) is responsible for performing all testing, inspection, and recording on the forms listed below. See Sections 706 and 712 of the MDOT Standard Specifications for Construction and the contract documents for the contractor’s responsibilities.
Form 1138, Bridge Reinforcing Computations
Complete Form 1138, Bridge Reinforcing Computations, for all concrete overlay pours prior to the commencement of the pour. Verify and record bar type, size, number, length, total length, weight per foot, total weight and add any remarks with regards to location (top mat, bottom mat, transverse, longitudinal, vertical, barrier, etc.).
Form 1125, Permit to Place
Complete Form 1125, Permit to Place, for all bridge deck concrete overlays. See the revised form. Mark “Conc, Bridge Deck Overlay” and select the concrete overlay mixture. Record the “Structure Number” and “Structure Location” concrete overlay material and any construction stages on the form. Issue permit to place only after approval of forms, reinforcing steel, and preparations for casting overlay concrete. This includes removing debris from the deck and forms, cleaning forms and steel reinforcement. The contractor must be able to provide a minimum 12-hour burlap soak for wet cure for bridge decks, have appropriate weather equipment to determine relative humidity temperature and wind speed for the determination of the evaporation rate, provide vibrators with rubber coated heads, provide ten foot straightedge for checking bridge deck trueness, and provide fogging equipment for the silica fume overlay.
Form 1131, Bridge Decks Concrete Depth Measurements
Complete Form 1131, Bridge Decks Concrete Depth Measurements for all bridge deck overlay pours. See Division 706 of the Construction Manual for a sample form and instructions. Verify and record the dry and wet run depth checks. Note the locations of the dry run measurements, and measure the wet run at or near the same locations. Measurement of the depth to the top mat of steel is not required for shallow overlays.
Form 1174A, Inspector’s Report of Concrete Placed
Complete Form 1174A, Inspector’s Report of Concrete Placed, for all bridge deck overlay concrete pours. See Division 6 of the Construction Manual for instructions. Note the form has been revised to include “Aggregate Correction Factor” and “Evaporation Rate” under “Structure Items Placed.” Use contractor-supplied weather equipment to determine and record the evaporation rate for bridge deck overlay pours if it is less than 0.15 psf per hour per Figure 706-1 of the MDOT Standard Specifications for Construction. Verify and record all concrete test results, tags, aggregate correction factor supplied from the concrete supplier, and overlay concrete quantities on the form.
Form 1122B, Inspector’s Daily Report
Complete Form 1122B, Inspector’s Daily Report, for all bridge work. See the Construction Manual for instructions. The engineer must also verify that the contractor provided weather equipment to determine the evaporation rate. Verify the slope and elevation of the expansion joint. Note any placement delays, inclement weather during the pour or any other factors that may have an adverse affect on the overall quality of the pour. Record hydrodemolition settings (water pressure, cutting head speed, and forward advancement).
MDOT Bridge Deck Overlay Construction Inspection Checklist (attached)
This checklist is an aid for documenting the inspection of bridge deck overlay construction. The checklist identifies important documentation items for testing and inspection, and items to observe during the bridge deck overlay operations. Complete the MDOT Bridge Deck Overlay Construction Inspection Checklist for all bridge deck concrete overlays. You can find the checklist here: MDOT form 2083
Bridge Deck Overlay Construction Inspection
Epoxy Coated Steel Reinforcement
Ensure the contractor is storing and covering the epoxy-coated steel reinforcement per the MDOT Standard Specifications for Construction to protect it from the sun’s ultraviolet rays. The engineer shall verify the contractor’s repair of epoxy coating using a patching/repair material selected from Section 905.03.C, Bar Reinforcement (Epoxy Coating) of the Qualified Products List. Note the repair product on Form 1122B, Inspector’s Daily Report and complete Form 1138, Bridge Reinforcing Computations. Ensure reinforcement is placed as shown on the plans and provide clear cover according to the plans and specifications. Verify the contractor is placing bar chairs as required in the MDOT Standard Specifications for Construction.
Concrete Testing
Ensure the contractor is performing concrete yield tests as part of the contractor’s concrete quality control. Subtract the aggregate correction factor from the field air content test results. Perform sampling of the concrete according to Michigan Test Method 207 at the pump discharge for silica fume modified concrete unless it is correlated to the concrete delivery truck. Note the correlation on Form 1122B, Inspector’s Daily Report.
Placing Bridge Deck Overlay Concrete
Verify that the silica fume modified concrete is falling less than 6 inches from the discharge chute to the uppermost steel reinforcement or existing bridge deck surface. For latex-modified concrete, the fall height of the mix is dependent on the air content and will vary.
Texturing and Curing Bridge Deck Overlays
Ensure that the contractor textures the deck as soon as the concrete has set sufficiently to maintain the texture, per the MDOT Standard Specifications for Construction. For silica fume modified concrete, ensure that the contractor applies a continuous fog to the screeded concrete. The engineer shall ensure the contractor wet cures the bridge deck per the MDOT Standard Specifications for Construction. Ensure that the contractor has soaked the burlap a minimum of 12 hours prior to beginning the deck pour, and the burlap is placed after the excess water is removed and as soon as the concrete will support it without deformation. Do not use Burlene directly on the bridge deck overlay concrete. Ensure that the contractor provides a network of soaker hoses and a system to apply cure water uniformly and continuously for at least 7 days for silica fume concrete and 2 days for latex modified concrete, and that the entire deck surface is covered with a minimum 4 mil polyethylene film.
Do not apply curing compound to latex-modified concrete or silica fume-modified concrete.
Concrete Delivery Tickets
Verify and record discharge time on the tickets and sign all of the concrete delivery tickets. Include any testing results (air, temperature, and slump) on the ticket.
For mobile mixer latex trucks, review the mix calibration and note the meter count on Form 1122B, Inspector’s Daily Report.
Concrete Trucks and Heavy Equipment
For deep overlays, do not allow concrete trucks and other heavy equipment (including vacuum trucks) to drive across the thinned bridge deck section and the exposed steel reinforcement. This prevents damage to the steel reinforcement and the remaining bridge deck concrete.
Notification
Notify John Belcher 517-937-7400 and Ethan Bahmer 517-230-0190 of the Construction Field Services Division’s Materials Section, one week prior to the commencement of the bridge deck concrete overlays.