8-128 Section 813. Slope Protection
813.01 Description
This work consists of constructing precast and cast -in-place (CIP) concrete slope paving, including plain, heavy, and grouted riprap and associated headers.
813.02 Materials
Provide materials in accordance with the following sections : Cement ................................................................................................. 901 Granular Material Class II ..................................................................... 902 Curing Compound ................................................................................. 903 Steel Reinforcement ............................................................................. 905 Geotextile Liner ..................................................................................... 910 Precast Concrete Slope Paving Blocks ................................................. 913 Riprap ................................................................................................... 916 Heavy Riprap ........................................................................................ 916 Concrete, Grade 3000 ........................................................................ 1004 Mortar, Type R -3 ................................................................................. 1005 Provide a retarding admixture, selected from the Qualified Products List, if additional time is required between adding water to the concrete mixture and placing the concrete. Do not exceed the man ufacturer’s recommended maximum initial set time.
813.03 Construction
A.Base Preparation . Excavate or fill to the required subgrade . Compact and shape the subgrade for the following:
1.The bottom of the riprap;
2.Precast and CIP concrete slope paving; or
3.The bottom of the granular material layer. Dispose of the surplus excavated subgrade material in accordance with subsection 205.03.P . Trim the subgrade to the Class A slope tolerances specified in subsection 205.03.N . Construct the granular material layer in accordance with subsection 301.03, except compact the material to at least 90 % of the maximum unit weight.
B.Precast Concrete Slope Paving . Place concrete in accordance with the weather and temperature limitations specified in subsection 602.03.T when fabricating precast concrete slope paving. Install the precast units on a layer of granular material base. Fill the joints between precast units MDOT Standard Specifications for Construction Section 813 8-129 with Type R -3 mortar . Moisten the edges of the precast units when placing the mortar . Place mortar beginning at the lower end of the joints and proceeding to the upper end of the joints . Completely fill the joints between the precast units after consolidation. Remove excess mortar from the surface of the slope paving. Cure and protect the m ortar in accordance with subsection 813.03.C.3.
C.Concrete Slope Pavin g
1.Forms . Use wood or metal forms that are straight and free of warp and capable of resisting deflection during concrete placement . Form the concrete full depth. Stake forms, including slab division forms, to the required line and grade. Provide straight and continuous slab division joints . Form blocks of the dimensions shown on the plans.
2.Placing and Finishing Concrete . Place concrete in accordance with the weather and temperature limitations specified in subsection
602.03 T . Maintain a moist base during concrete placement . Place
concrete to the required depth in a continuous operation. Place concrete within 1½ hours of adding water into the mix . Do not retem per. Consolidate the concrete along the faces of the forms . Tamp the concrete surface to remove voids and strike off with a strike board to the required grade and cross section. Finish the concrete surface with a wood float . Round the edges and joints to a ¼-inch radius with a Department -approved finishing tool . Remove edging and finishing tool marks with a float and soft bristle brush.
3.Curing and Protection . Cure the concrete by applying a transparent membrane curing compound specified in subsection 903.07.B.
D.Slope Paving Headers. Use forms for slope paving headers in accordance with subsection 813.03.C.1. If concrete placement is required below the elevation of the slope paving subgrade, or granular material layer, the concrete may be cast neat to the earth, as approved by the Engineer. Place steel reinforcement in accordance with subsecti on 802.03.C . Place and finish slope paving header concrete in accordance with subsection
813.03 C.2. Cure slope paving header concrete in accordance with
subsection 813.03.C.3.
E.Riprap . Place geotextile liner under the riprap. Place the liner in a key trench at the toe of the slope if the riprap ends at or below a high water MDOT Standard Specifications for Construction Section 813 8-130 elevation. After the riprap is in place, anchor the geotextile in a key trench at the tops of slopes with a ratio of 1:3 or steeper . Construct the upper key trench t o 1½ feet deep or three times the minimum riprap dimension, whichever is greater . Provide a setback between the top of the slope and the upper key trench at least equal to the trench depth. Backfill the upper trench with riprap material unless otherwise directed by the Engineer. Overlap geotextile seams by at least 2 feet. If laying geotextile horizontally, start at the bottom of the slope and shingle lap additional layers to direct surface runoff . Place riprap onto the geotextile without dumping or dropping riprap into place.
1.Plain Riprap. Begin the riprap placement in the trench at the toe of the slope and progress upward. Place individual stones, embedding each stone into the slope, and interlock a gainst adjoining stones . Place random and well -broken joints between consecutive rows of stones . Compact the riprap as construction progresses . Unless using precast concrete blocks, construct riprap at least 1 8 inches thick , measured perpendicular to the s lope.
2.Grouted Riprap . Place riprap in accordance with subsection
813.03 E.1. Fill the spaces between the stones with Type R -3 mortar .
Place the mortar from joint bottom to top and completely fill the voids between the stones after consolidation. Leave the top surface of the stone exposed. Immediately remove excess mortar with a stiff brush. Cure and protect grouted riprap in accordance with subsection
813.03 C.3.
3.Heavy Riprap . Place heavy riprap in accordance with subsection
813.03 E.1. Unless using precast concrete blocks, construct heavy
riprap at least 3 6 inches thick, measured perpendicular to the slope. If using broken concrete, place in two layers with staggered joints and fill voids with smaller pieces of broken concrete , as approved by the Engineer.
813.04 Measurement and Payment
Pay Item Pay Unit Slope Paving, Precast Conc .......................................................... Square Yard Slope Paving, Conc ....................................................................... Square Yard Slope Paving Header ................................................................................. Foot Riprap, Grouted ............................................................................. Square Yard Riprap, Plain .......................................................................... Square Yard, Ton Riprap, Plain, LM ............................................................................. Cubic Yard Riprap, Heavy ........................................................................ Square Yard, Ton Riprap, Heavy, LM ........................................................................... Cubic Yard MDOT Standard Specifications for Construction Section 813 8-131 A. Concrete Acceptance. Conduct concrete QC as specified in section 1002. The Engineer will conduct QA as specified in section 1003. The Department will pay for this work based on the QA results.
B.Slope Paving . The unit prices for slope paving pay items include the cost of admixtures , excavation, and disposal of surplus materials . The unit prices for slope paving pay items also include the cost of granular material, unless the plans include the pay item Granular Material , Cl.
C.Slope Paving Header . The Engineer will measure Slope Paving Header in place, including both sides and the toe.
D.Riprap . The unit prices for riprap items include furnishing all materials, equipment , and labor to divert stream flow, clear and prepare grades, excavate and dispose of surplus or unsuitable materials, furnish and place geotextile liner or heavy geotextile liner as applicable, and place the riprap, including headers.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 689–692 of 1,146.