Use Entire Spec If You Have 4000 Psi, In., 585 Hp Cement Concrete (30 Mpa - 20 Mm - 345

Issue Date: 12/14/2017 PLACEMENT, FINISHING AND CURING OF CAST IN PLACE CONCERETE DECKS

The construction of the cast in place concrete deck shall be in accordance with Subsection 901.66 of the Supplemental Specifications and as modified by the following.

These procedures shall be followed only when the concrete bridge deck shall be cast entirely in the field. These procedures do not apply to any precast deck components, including precast full depth concrete deck panels and decks cast as part of a prefabricated bridge unit (PBU), or closure pours used to connect precast decks in the field.

Subsection 901.66 A The entire existing Subsection 901.66 A shall be replaced by the following:

At least 30 calendar days prior to the proposed start of placing the concrete bridge deck, the Contractor shall submit to the Engineer for approval a Placement and Curing Plan that will specify all of the steps, methods, equipment and personnel that Contractor shall use to construct the concrete deck in compliance with these specifications. Approval of this plan will not relieve the Contractor of the responsibility for the satisfactory performance of his/her methods and equipment. The Placement and Curing Plan shall, at a minimum, specify:

1. The method that will be used to convey the concrete from the truck to all locations on the deck where it will be placed. This will also include the conveyance equipment, rate of concrete placement and the estimated time for the completion of all concrete placement, consolidation and finishing operations up to the start of curing. 2. The type and number of finishing machines and work bridges including the plan for erecting the rails and operating the finishing machine. This will include proof of the following minimum operator qualifications for the bridge deck finishing machine: a) Five years experience operating machines or similar type and manufacturer as that proposed. b) Proof of no less than five bridge decks of similar size, placed using a machine of the same manufacturer as that proposed. Or, as a substitute for a. and b.: c) A representative of the manufacturer of the bridge deck finishing machine shall be present on the site a minimum of 24 hours in advance of the proposed deck placement to approve the setup of the machine and rail system, and the representative shall be present for the entire duration of the placement of the deck concrete using the bridge deck finishing machine. 3. The sequence of concrete pours, including any retarders or other concrete admixtures and dosage rates required to complete the placement, consolidation and finishing operations prior to curing in accordance with the Contractor’s intended sequence of operations. 4. The provisions for consolidating the concrete including the number of vibrators and number of personnel that will be dedicated exclusively for this operation. 5. The method for curing the concrete deck. This will include the number of personnel that

1 Issue Date: 12/14/2017 will be exclusively dedicated for this operation, the means for pre-wetting the burlap, the location of the wet burlap at the work site, the means for conveying the wet burlap to the work bridges and the amount of wet burlap that will be required to completely cover the deck. It shall also include a letter certifying that the fogging equipment attached to the finishing machine produces atomized water droplets with an average droplet diameter of 0.003 inches (76 μm) or less that are uniformly distributed at a rate of at least 0.10 gallons/square foot/hour (4 liters/square meter/hour) 6. Consideration of weather conditions that can be anticipated at the time of placement of the deck concrete. When cold weather can be reasonably expected either within 7 days before the anticipated concrete placement, or during the 14 day wet curing period, the Contractor shall include detailed procedures for the production, transportation, and placement of the concrete, including: provisions for enclosures to protect the placed concrete, including a plan of heating devices, types and locations around structure and the means for holding the enclosure securely in place; cold weather curing procedures; and the means for monitoring the temperature of concrete during cold weather. 7. Equipment that will be used to measure ambient air temperature, concrete temperature and relative humidity of the air at the construction site. 8. The number of all other personnel, in addition to the ones already identified in bullets 4 and 5, who will be engaged in the concrete placement operation and their assigned tasks. All personnel, including the ones already identified in bullets 4 and 5, shall have the experience and skills appropriate to their working assignment 9. A contingency and backup plan in case of equipment failure.

A pre-placement meeting shall be held between the Contractor and the Engineer at least 2 weeks prior to the start of any concrete placement for the deck slab. The Contractor and the Engineer shall review all aspects of the approved Placement and Curing Plan.

Twenty four (24) hours before the scheduled start of concrete placement, the Engineer shall verify that all equipment and materials identified in the Placement and Curing Plan are onsite and have been tested to insure that they are in working order and are functioning as required. Upon the successful completion of this verification, the Engineer shall allow the concrete placement to proceed. If any equipment or material such as burlap is missing or equipment is malfunctioning, the concrete placement operations shall be canceled and shall not be re- scheduled until such time as the missing equipment or material is delivered to the site or the equipment has been repaired and is demonstrated to be in working order and functioning as required. The Contractor shall be responsible for any costs associated with the cancellation and rescheduling of the concrete placement operation that is due to missing equipment or material or malfunctioning equipment.

Subsection 901.66 B The following shall be added to the requirements of the existing Subsection 901.66 B:

Cement concrete for bridge decks shall not be placed when the ambient air temperature exceeds

2 Issue Date: 12/14/2017 85°F (29°C) or is expected to exceed 85°F (29°C) during the placement of the deck. The Contractor shall measure the ambient air temperature, relative humidity of the air at the construction site and concrete temperature. Concrete temperature will be taken from the same sample used for slump and air content tests. These measurements will be taken prior to the commencement of concrete placement to determine the evaporation rate using Figure 1 and every hour thereafter until the end of the concrete placement, consolidation and finishing operation to check the evaporation rate in order to determine if it remains within the limits specified. To document the readings, the Bridge Deck Placement Environment form shown below shall be filled out by the Contractor and submitted to the Engineer.

Bridge Deck Placement Environment City/Town: Date: Bridge Number: Contract Number: Start Station: End Station: Relative Time Air Concrete Wind Evaporation Humidity Measured Temp. Temp. Velocity Rate (%) Prior to Casting Hourly

After Casting Signature - Contractor’s Authorized Printed Name: Representative: Signature - MassDOT Resident Engineer: Printed Name:

The existing Subsection 901.66 B 1 shall be replaced by the following:

1. Misting the surface of the concrete with pressurized equipment attached to the finishing machine until the curing cover is applied. The water mist shall be distributed at a rate of at least 0.10 gallons/square foot/hour (4 liters/square meter/hour). For example, on a deck that is 30 feet (9.1 meters) wide, the system must be able to apply at least 3.0 gallons of water per linear foot per hour (36.4 liters/meter-hour). The nozzles must produce an atomized fog mist that will maintain a sheen of moisture on the concrete surface without ponding. The atomized water droplets shall have an average droplet diameter of 0.003 inches (76 μm) or less. The area of coverage from each nozzle shall overlap all adjacent coverage areas by at least 12 inches (305 millimeters). Water that drips from the nozzles shall not be allowed to fall onto the concrete that is being cured. 3 Issue Date: 12/14/2017

The following shall be added to the requirements of the existing Subsection 901.66 B:

4. Reschedule the placement until such time as the environmental conditions are acceptable, such as at night or during early morning hours.

Subsection 901.66 D The entire existing Subsection 901.66 D shall be replaced by the following:

The concrete shall be consolidated by means of approved high frequency internal vibrators (9000 – 12,500 vibrations per minute in concrete) that shall be applied in a manner to ensure the consolidation of the concrete throughout the full depth of the deck in advance of the finishing machine. The Contractor shall take preventive measures to insure that the vibrators during operation shall not damage the epoxy coated reinforcement. The Contractor shall have no less than 2 approved vibrators in service at all times during the placement of the first 30 cubic yards (27 cubic meters) per hour of cement concrete placed and shall have additional vibrators in service at all times at the rate of one vibrator per each additional 30 cubic yards (27 cubic meters) per hour of cement concrete placed. These vibrators shall be in operation in addition to the surface vibratory action from the vibrating pan(s) of the finishing machine. Consolidation by the vibrators shall leave the concrete free from voids and insure a dense surface texture, but the vibration of the concrete shall not be continued so long as to cause segregation or bleeding. A small uniform quantity of concrete shall be maintained ahead of the screed on each pass. At no time shall the quantity of concrete carried ahead of the screed be so great as to cause slipping or lifting.