2533Concrete Median Barriers

2533.1DESCRIPTION

This Work consists of constructing or reconstructing cast-in-place median barrier or precast median barriers for Traffic Lane separation.

2533.2MATERIALS

A.1 Fixed Form Cast-In-Place ........................................................................... Mix No. 3M52 A.2 Slipform Placement .................................................................................. Mix No. 3M12 A.3 Precast ...................................................................................................... Mix No. 3M82 E Curing Materials

2533.3CONSTRUCTION REQUIREMENTS

A General The Contractor may combine cast-in-place and precast concrete construction as approved by the Engineer if the Plans do not specify the construction type and if the construction maintains structural strength, continuity, or both. Use a tongue and groove joint with tied dowels or reinforcement bars or other positive connection to interlock the connection between a new median barrier and an existing barrier to prevent movement, as approved by the Engineer. Excavate, shape, and compact the foundation to a firm, uniform bearing surface and grade as shown on the Plans and in accordance with 2106, “Excavation and Embankment – Compacted Volume Method,” 2112, “Subgrade Preparation,” and 2211, “Aggregate Base.” B Cast-In-Place Fixed Form Construction Provide forms made of non-reactive metal, wood, or other Material in accordance with 1805, “Methods and Equipment,” capable of maintaining the concrete until the concrete can retain the molded shape. Provide side forms with a depth at least equal to the edge thickness of the formed concrete. Support the forms on the foundation to maintain the concrete line and grade as shown on the P lans. Before placing the forms, coat the contact surfaces of the forms with an approved form treating Material in accordance with 3902, “Form Coating Material.” Wet the foundation and forms immediately before placing the concrete. Prevent segregation during placement of concrete. Use internal vibration to consolidate the concrete and fill voids. Strike-off the concrete to the grade as shown on the Plans and float the surface smooth. When the concrete can retain the molded shape, remove the forms from the Roadway face of the median barrier. Keep non-Roadway face forms in place for at least 12 hours after casting the concrete. Round concrete edges to the radii as shown on the Plans after removing the Roadway face forms. C Cast-In-Place Slipform Construction Rather than using fixed forms, the Contractor may use a slipform machine capable of placing and forming concrete to the dimensions, quality, workmanship, and appearance as required by the C ontract. Hand finish the concrete surface to the finish and texture as required by the C ontract. D Surface Finishes D.1 Cast-In-Place Apply an ordinary surface finish in accordance with 2401.3F, “Finish of Concrete,” on cast-in-place concrete median barriers. D.2 Precast Place the barrier in its final location. Obtain the Engineer’s approval of the surface condition of the barrier before applying the special surface finish treatment on precast concrete median barrier in accordance with 2401.3F, “Finish of Concrete.” E Concrete Curing and Protection Curing requirements for roadside concrete median barriers shall conform to 2401.3G.1, “Minimum Curing Period,” Table 2401.3-2. When the Contract requires additional surface finishing (i.e. painting), cure in accordance with 2533.3E.1.b. “Curing Blanket Method.”

After completing final finishing operations, cure exposed concrete surfaces . Use one of the following curing methods:

curing compound conforming to 3754, “Poly-Alpha Methyl Styrene (AMS) Membrane Curing Compound,” or 3755, “Linseed Oil Membrane Curing Compound,” within 30 minutes of concrete placement or once the bleed water has dissipated, unless otherwise directed by the Engineer. Place the membrane curing compound on the edges within 30 minutes after permanent removal of the forms or curing blankets, unless the Contract requires otherwise.

practical without marring the surface in accordance with 2533.3E.1.b , “Curing Blanket Method.” Whenever weather conditions are such as to cause unusual or adverse placing and finishing conditions, expedite the application of a curing method or temporarily suspend the mixing and placing operations, as the conditions require. If necessary to remove the coverings to saw joints or perform other required W ork, and if the Engineer approves, remove the covering for the minimum time required to complete that W ork. E.1 Curing Methods E.1.a Membrane Curing Method Before application, agitate the curing compound as received in the shipping container to obtain a homogenous mixture. Protect membrane curing compounds from freezing before application. Handle and apply the membrane curing compound in accordance with the manufacturer’s recommendations. The Engineer will only approve airless spraying machines equipped with a recirculating bypass system that provides for continuous agitation of the reservoir Material, separate filters for the hose and nozzle, and multiple or adjustable nozzle system that provides for variable spray patterns. Apply the curing compound with an approved airless spraying machine in accordance with the following:

area.

coverage on exposed concrete surfaces (equal to a white sheet of copy paper) at the time of application. Some Department approved curing compounds may have a base color (i.e. yellow) that cannot comply with the above requirement. In this case, provide a uniform, solid, opaque consistency meeting the intent of the above requirement.

immediately repair the damaged area by respraying. If the Engineer determines that the initial or corrective spraying i s unsatisfactory curing, the Engineer may require the Contractor to use the blanket curing method, at no additional cost to the Department.

E.1.b Curing Blanket Method After completion of the finishing operations and without marring the concrete, cover the concrete with curing blankets. Install in a manner that envelops the exposed concrete and prevents loss of water vapor. After the concrete has cured, apply membrane curing compound to the concrete surfaces that will remain exposed in the completed Work. E.2 Protection Against Rain Protect the concrete from damage due to rain. Have available, near the site of the Work, Materials for protection of the edges and surface of concrete. Should any damage result, the Engineer will suspend operations until the Contractor takes corrective action, and may subject the rain-damaged concrete to 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” E.3 Protection Against Cold Weather If the National Weather Service forecast for the construction area predicts air temperatures of 36°F or less within the next 24 hours and the Contractor wishes to place concrete, submit a cold weather protection Plan. Protect the concrete from damage including freezing due to cold weather . Should any damage result, the Engineer will suspend operations until the Contractor takes corrective action, and may subject the damaged concrete to 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” E.3.a Cold Weather Protection Plan Submit a proposed time schedule and Plan for cold weather protection of concrete in writing to the Engineer for acceptance that provides provisions for adequately protecting the concrete during placement and curing. Do not place concrete until the Engineer accepts the cold weather protection Plan. F Finish and Workmanship Produce concrete barrier to the dimensions and height shown in the P lans. Finish concrete barrier to a neat uniform surface finish with a light (vertical) broom texture before applying the curing medium. The Engineer may use a 10 foot straightedge to measure the barrier surface for irregularities.

2533.4METHOD OF MEASUREMENT

The Engineer will linearly measure each Type A and Type AA concrete median barrier on the top of the barrier, measured along the midpoint of the top width. The Engineer will linearly measure Type A barrier with glare screen in accordance with Type A and Type AA barrier or measured along both sides the barrier with a computed average of both measurements. The Engineer will take both measurements at the interface of the barrier and adjacent pavement. The Engineer will linearly measure transitions, and special and modified barriers by the length on the top of the barrier, measured along the midpoint of the top width. The Engineer will separately measure each type of concrete median barrier. When portable median barrier is removed from the Project Roadway and the Engineer directs stockpiling the portable median barrier on or near the Project Site for use again in a later phase of the Work, the Engineer will separately measure the stockpiled length of barrier and also the length of barrier reinstalled on the Project Roadway. The Engineer will only measure the stockpiled barrier when the Contract Unit Price for double payment of Relocate Portable Precast Concrete Barrier, Design 8337 and/or Relocate Portable precast concrete barrier, Design 8337 - Anchored would equate to lower price than furnishing Portable Precast concrete barrier, Design 8337.

2533.5BASIS OF PAYMENT

The Contract Unit Price for concrete median barrier construction includes furnishing the Materials, placement of the Work to the lines and grade on the Plans, and surface finish as specified. The Contract Unit Price for portable precast concrete barrier includes costs of installation and removal once. The Contract Unit Price for relocating portable precast concrete barrier includes removing, stockpiling, and reusing as directed by the Engineer. A Monetary Adjustments The Department must apply Incentives and Disincentives and may apply monetary deductions for Concrete Median Barriers. The amounts of these adjustments are deemed reasonable. A.1 Concrete Curing and Protection Failure to properly cure and protect the concrete in accordance with 2533.3E , “Concrete Curing and Protection,” will result in the Engineer applying a monetary deduction in accordance with 1503, “Conformity with Contract Documents,” and 1512, “Unacceptable and Unauthorized Work.” If the Contract does not contain a separate Contract Item for structural concrete, the Department will apply a monetary deduction of $50.00 per cubic yard or 50 percent of the Contractor-provided invoice amount for the concrete in question, whichever is less. A.2 Finish and Workmanship The Engineer will consider surface irregularities greater than the following as unacceptable Work:

1/4 inch.

irregularities) greater than 1/2 inch.

irregularities) greater than 1 inch.

irregularities) greater than 1 3/4 inches. The Engineer will evaluate unacceptable Work in accordance with Table 2533.5-1. Table 2533.5-1 Monetary Deductions for Workmanship Amount of Surface Irregularities (Measured by Length) Corrective Action Monetary Deduction ≤ 10 percent of median barrier length * Monetary Deduction The Engineer will reduce payment for the length of out-of-tolerance barrier by up to 50 percent of the Contract Unit Price. > 10 percent of median barrier length * Remove and Replace or Monetary Deduction If the Engineer does not direct removal and replacement, the Engineer will reduce payment for the length of out-of-tolerance barrier by 50 percent of the Contract Unit Price. * Based on the measured length for each separate barrier Pay Item on the Project.

B Schedule The Department will pay for Concrete median barrier on the basis of the following schedule: Item No. Item Unit

2533.503 Concrete Median Barrier Des ___* Type ___ǁ linear foot

3 Conc Med Bar Des Single Slope Type ___ǁ linear foot

3 Conc Med Bar & Gl Scr Des ___* Type ___ǁ linear foot

3 Portable Precast Concrete Barrier Design ___* linear foot

3 Relocate Portable Precast Concrete Barrier, Design ___* linear foot

* Current Standard Plate or Plan ǁ Type A, Type AA, TypeAL, Transition, A Step, or AA Step