173 SECTION 256
256.01 Description
This work consists of furnishing or salvaging, and placing stones on slopes, channel ways, or other areas.
256.02 Equipment
Reserved.
256.03 Materials
A.General. Use stone that is clean and free of deleterious material.
B.Grout. Proportion grout using one part Portland Cement and two parts sand by volume.
C.Riprap. Use field stone or quarry stone as riprap.
1.Gradation. Table 256 -01 Riprap Gradations Grade I Grade II Grade III Size (Inches) Percent Smaller Size (Inches) Percent Smaller Size (Inches) Percent Smaller 20 100 28 100 36 100 18 70-90 22 30-80 29 55-85 15 40-60 16 20-50 24 35-50 10 0-10 10 0-5 10 10-15 6 0-2 6 0-2 6 0-2
2.Field Stone. Do not use field stone that: − Consists of sandstone, shale, or soft limestone; − Contains cracks or flaws that would cause splitting or breakup; or − Is easily abraded or crushed.
3.Quarry Stone. Do not use quarry stone that consists of sandstone, limestone, or stone of sedimentary origin. Provide quarry stone that would meet the requirements of Table 256-02, if the stone was properly processed. 174 Table 256 -02 Quarry Stone Properties Test Method Max. Percent by Weight of the Plus No. 4 fraction
L.A. Abrasion AASHTO T 96 40.0 Soundness (Sodium Sulfate) AASHTO T 104 12
256.04 Construction Requirements
A.General. Place the stones on sloped areas beginning at the toe of the slope. Set stones to obtain an even outer surface and a uniform appearance.
B.Riprap. Dig a trench at least one foot deep and place the largest stones in the trench, filling gaps with smaller stones. Place stones by mechanical means or by hand. Distribute stones evenly over the riprap area without: − Material segregation − Deviating from designed slope and grade by greater than 6 inches Do not drop riprap stones from a height greater than 3 feet. Place stones greater than 250 pounds with no free-fall. Achieve contouring of the stones during initial placement. Do not roll the stones along the surface. Begin placement of the stone cover at the base of the slope and at the center of the fabric covered zone.
C.Grout. Dampen riprap before applying grout. Recess the grout 1 to 3 inches below the top of the riprap.
256.05 Metho D of Measurement
The Engineer will measure, completed and in place, as specified in Section 109.01, “Measurement of Quantities” and as follows: The Engineer will measure the actual surface dimension of grouted riprap to determine the amount of grout placed.
256.06 Basis of Payment
Pay Item Pay Unit Riprap Grade __ Cubic Yard or Ton Grout for Riprap Square Yard Include excavation and shaping necessary to place the riprap or bedding stone in the price bid for these items. 175 Such payment is full compensation for furnishing all materials, equipment, labor, and incidentals to complete the work as specified. Section 258 176 SECTION 258 CONCRETE SLOPE PROTECTION
258.01 Description
This work consists of placing cast-in -place concrete slope protection.
258.02 Equipment
Reserved.
258.03 Materials
Material Section AE-3 Concrete 802 Preformed Expansion Joint Filler 826.02 Joint Seal ant 826.02 A.2 Reinforcing Steel 836.02 Steel Welded Reinforcement, Plain, for Concrete 836.03 B
258.04 Construction Requirements
A.Preparation of Subgrade. Remove vegetation and deleterious material. Compact all loose material. Wet surfaces before placing concrete. Do not place concrete on soft subgrade or in standing water.
B.Placing Concrete. Place and consolidate concrete using methods that prevent segregation and sagging. Place a construction joint at the end of the panel if placement of concrete is stopped for more than 30 minutes.
C.Transverse Grooved Joints. Construct transverse grooved joints in the surface of the plastic concrete. Maintain the transverse grooved joints during finishing operations until the concrete has hardened. Seal the joints after the concrete becomes stiff enough to prevent distortion to the groove or damage to the concrete. Clear the joints of foreign material and water before sealing. Apply the sealer with a caulking gun or other approved device.
D.Finishing Concrete. Finish the surface so there are no ir regularities greater than 0.75 inch in 10 feet.
E.Curing Concrete. Cure concrete as specified in Section 550.04 I, “Curing Concrete” , with the following exception: Cure the concrete for a minimum of 5 days.
Source: North Dakota Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 208–210 of 550.