8-132 Section 814. Paved Ditches
814.01 Description
This work consists of constructing paved ditches using cobble, concrete, or HMA.
814.02 Materials
Provide materials in accordance with the following sections: HMA Mixture ......................................................................................... 501 Curing Compound ................................................................................. 903 Steel Reinforcement ............................................................................. 905 Geotextile Liner ..................................................................................... 910 Cobblestones ........................................................................................ 916 Concrete, Grade 3000 ........................................................................ 1004 Mortar, Type R -3 ................................................................................. 1005
A.HMA Paved Ditches. Provide HMA that matches the shoulder leveling course HMA as shown on the plans . Obtain the E ngineer’s approval for the HMA mixture in accordance with section 501.
B.Concrete Paved Ditches. Provide a retarding admixture, selected from the Qualified Products List, if placing concrete more than 1½ hours after adding water to the concrete mixture, but do not exceed the manufacturer’s recommended maximum initial set time.
814.03 Construction
A.Preparation of Base. Excavate, shape, and compact the base to the required cross section and elevation. For concrete paved ditches, excavate to allow for installing and bracing forms . Dispose of surplus excavated material in accordance with subsection 205.03.P. Prior to placing riprap, line the width of the ditch bottom, as shown on the plans, with geotextile liner . Do not use longitudinal seams . Begin placement of the geotextile liner at the downslope end of the ditch and shingle lap geotextile liner at least 2 feet. Extend geotextile liner under the HMA paved ditch to create at least a 1-foot overlap or as shown on the plans.
B.Plain Cobble Ditch . Place cobblestones or broken concrete on the prepared base with the longest dimensions parallel with the centerline of the ditch and smallest faces upward. Place the outer rows first, using the larger cobblestones or broken concrete. Place the cobblestones or broken concrete by hand and stagger the joints . Use a tamper of at least MDOT Standard Specifications for Construction Section 814 8-133 30 pounds to uniformly bed cobblestones and broken concrete in the base. Do not place crushed concrete within 100 feet of any water course (stream, river, county drain, etc.) or lake, regardless of the application or location of the water course or lake relative to the project limits.
C.Grouted Cobble Ditch . Begin work at the lowest el evation of the ditch. Place a layer of mortar on the prepared base to embed the lower half of the cobblestones or broken concrete and fill the spaces between the cobblestones or broken concrete with mortar . Place the cobblestones or broken concrete in accordance with subsection 814.03.B . Add and consolidate mortar to fill voids to within 1 inch of the top of the cobblestones or broken concrete, leaving the top surface exposed. Cure and protect the grout in accordance with subsection 814.03.E.5.
D.HMA Paved Di tch. Do not place HMA on frozen material . Place the HMA mixture adjacent to the proposed shoulder at the leveling course elevation on the prepared base to a thickness of at least 3 inches and to at least 330 pounds per square yard, or as detailed on the pl ans. Cover the ditch bottom and side slopes . Feather down the top course mixture at the location of the paved ditch when the top course is constructed. Place HMA using mechanical or hand methods, as approved by the Engineer . Compact the material using a roller, mechanical compactor, or hand tamper . Check the ditch grade during paving and provide positive drainage.
E.Concrete Paved Ditches
1.Forms . Use wood or metal forms that are straight and not warped. Forms must be braced to resist deflection during concrete placement . Provide forms with a vertical face equal to the required concrete thickness. If concrete placement is required below the ditch subgrade, the concrete may be cast neat to the earth, as approved by the Engineer.
2.Steel Reinforcement . Place steel reinforcement in accordance with subsection 802.03.C.
3.Placing and Finishing Concrete . Place concrete in accordance with the temperature and weather limitations specified in subsection 602.03.T . Wet the base immediately before placing concrete. Consolidate the concrete along the faces of the forms and next to the MDOT Standard Specifications for Construction Section 814 8-134 joints . Tamp the concrete surface to remove voids, strike off, and float to the required grade and cross section. Do not retemper the concrete. Round the edges and joints of the pavement to a ¼-inch radius with a finishing tool . Remove edging and finishing tool marks with a float and soft bristle brush.
4.Joints . Construct plane-of -weakness joints in accordance with subsection 803.03.D.
5.Curing and Protection . Cure the concrete by applying a transparent membrane curing compound specified in subsection 903.06.B.
814.04 Measurement and Payment
Pay Item Pay Unit Ditch, Plain Cobble ........................................................................ Square Yard Ditch, Grouted Cobble ................................................................... Square Yard Paved Ditch, HMA ......................................................................... Square Yard Paved Ditch, Conc ......................................................................... Square Yard Conduct concrete QC as specified in section 1002. The Engineer will conduct QA as specified in section 1003. The Department will pay for Paved Ditch, Conc based on the QA results and this section. The cost of concrete, grout admixtures, HMA , geotextile liner, and cobble is included in the unit price of related paved ditch pay items. The Engineer will measure and the Department will pay for cobble or paved ditch items based on in-place square yards. Riprap used in conjunction with cobble and paved ditch items will be measured and paid for separately.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 693–695 of 1,146.