308 ALASKA 2020 SECTION 611
611-1.01 DESCRIPTION . Construct riprap bank and slope protection.
611-2.01 MATERIALS. Evenly graded stones that are hard, angular, and have no more than 50
percent wear at 500 revolutions as determined by AASHTO T 96. Use stones with breadth and thickness at least 1/4 of its length. Do not use rounded boulders or cobbles on slopes steeper than 2:1. Meet the following gradation for the class specified. Percentages are by total weight, weights are for each stone:
1.Class I 0-50% weighing up to 25 pounds 0-10% weighing more than 50 pounds
2.Class II 50-100% weighing 200 pounds or more 0-15% weighing up to 25 pounds 0-10% weighing more than 400 pounds
3.Class III 50-100% weighing 700 pounds or more 0-15% weighing up to 25 pounds 0-10% weighing more than 1400 pounds
4.Class IV 50-100% weighing 2000 pounds or more 0-15% weighing up to 400 pounds 0-10% weighing more than 5400 pounds
611-3.01 CONSTRUCTIO N REQUIREMENTS. Provide a level, compact area large enough to
dump and sort typical loads of riprap at approved location(s). Dump the loads specified in this area and assist the Engineer as needed to sort and measure the stones in the load to determine if the riprap is within specifications. Provide the equipment needed to assist in this sorting. Excavate a footing trench along the toe of the slope as shown on the Plans. Place stones to the thickness , height, and length shown on the Plans, or as staked, in a well - graded mass with a minimum of voids. Fill in unacceptable voids with smaller stones. Place riprap to its full course thickness in one operation. Avoid displacing the underlying material. Do n ot place riprap in layers or use methods likely to cause segregation. Manipulate the rock sufficiently using a backhoe, rock tongs, or other suitable equipment to secure a reasonably regular surface and stability.
611-4.01 METHOD OF M EASUREMENT. See Secti on 109, by neat line volume or by weight.
611-5.01 BASIS OF PA YMENT. Excavation and backfill are subsidiary.
Payment will be made under: PAY ITEM Item Number Item Description Unit 611.0001.____ Riprap, Class ___ CY 611.0002.____ Riprap, Class ___ TON 611.0003.____ Riprap, Class ___ LS 309 ALASKA 2020 SECTION 612 SACKED CONCRETE SLOP E PROTECTION
612-1.01 DESCRIPTION . Construct sacked Portland cement concrete slope protection.
612-2.01 MATERIALS. Use materials that conform to the following:
Portland Cement . See Section 701 Aggregate. Plasticity Index of 5 maximum, as determined by ATM 204 and ATM 205. Meet the following gradation, as determined by ATM 304: Sieve Percent Passing 2-1/2 inch 100% No. 4 45 - 80% No. 200 0 - 10% Concrete Mix . Cement content: 4 sacks per cubic yard. Slump: 3 to 5 inches. Sacks . Use new or sound reclaimed sacks made of at least 10- ounce burlap or equivalent and approximately 19- 1/2 by 36 inches, measured inside the seams when the sack is laid flat. The capacity of each sack must be approximately 1.25 cubic feet.
612-3.01 CONSTRUCTIO N REQUIREMENTS. Smoothly finish the slopes on which the sacked
concrete is to be placed within 0.2 foot of the design grade. Place approximately 1 cubic foot of concrete in each sack. Immediately close the sack, place it in position, and lightly tamp it to conform with the slope and the adjacent sacks in place. “Stretcher,” as used herein, means a filled sack placed with its long dimension parallel to the contour of the slope. “Headers” are filled sacks placed at right angles to the stretchers. Lay the courses as follows:
1.First Course . Lay a double row of stretchers in a neatly trimmed trench.
2.Second Course. Lay a single row of headers.
3.Third and Remaining Courses . Place a single row of stretchers so tha t joints in succeeding courses are staggered. Place stretchers so that the folded ends will not be adjacent to one another. Place headers with the folds in toward the bank. Remove all dirt and debris from the top of the sacks before laying the next cours e on top. Do not place more than 4 courses of sacks in any tier until initial set has taken place in the first course of the tier. If delays occur in placing succeeding layers of sacks, apply dry cement to the joint before placing the succeeding course, as directed. Cure sacked concrete slope protection by sprinkling with a fine spray of water every 2 hours during the daytime for 3 days.
612-4.01 METHOD OF M EASUREMENT. By each sack complete in place.
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 336–336 of 584.