- 732 - SECTION 905 -- ROCK RIPRAP
905.01 Description
1.The Contractor shall prepar e the slopes and furnish and place stone on the slopes at locations shown in the contract.
905.02 Material Requirements
1.a. The rock shall be sandstone , limestone, quartzite, or other hard stone. It shall be clean and free from earth, clay, or refuse.
b.The solid rock shall have a density of at least 140 lb/CF (2245 Kg/m3).
2.Each load of rock shall be graded as shown in Table 905.01. The rock shall be angular in shape to allow interlocking between the various rock sizes. Table 905.01 Gradation Requirements Size of Rock Percent of Total Weight Smaller than the Given Size Type A 150 pounds (68 Kg) 35 pounds (16 Kg) 2 pounds (0.9 Kg) Not to exceed 10 Type B 300 pounds (136 Kg) 80 pounds (36 Kg) 5 pounds (2.2 Kg) Not to exceed 10 Type C 700 pounds (318 Kg) 150 pounds (68 Kg) 10 pounds (4.5 Kg) Not to exceed 10
3.a. Gradation control shall be done by a visual inspection that verifies the rock is reasonably well graded and does conform to the gradation requirements in Table 905.01.
b.Each piece shall have no dimension greater than 3 times its least dimension.
4.Rock riprap shall not have a soundness loss greater than 14% by weight at the completion of 16 cycles of freezing and thawing when tested in accordance with NDOT T 103. The rock riprap shall be prepared for the freezing and thawing tests by crushing to comply with the gradation requirements of coarse aggregate, as specified in Section 1033, Table 1033.03A, Class "E" aggregate.
905.03 Construction Methods
1.a. The finished earth surface shall conform to the grades and slopes of the neat lines of the bottom surface of the riprap as shown in the contract.
b.The Contractor shall excavate for energy dissipation holes (scour holes) as described in the contract. Rock Riprap 905.05 - 733 - c. Depressions shall be filled with suitable dry material which shall be thoroughly tamped or otherwise compacted to insure stability.
d.Soft, unstable materials sh all be removed and replaced with suitable material which shall be thoroughly tamped or otherwise compacted to insure stability. No raised places, bumps, or depressions will be allowed.
2.The approved rock shall be placed in such a manner as to produce a stable mass of rock within the limits shown in the contract or specified by the Engineer. All material shall be placed and distributed so that there will be no large accumulations of either the larger or smaller sizes of rock.
3.Any appreciable variation from t he specified thickness of the riprap shall be corrected by redistributing the rock.
4.All riprap placed will be covered with native soil and seeded above the historical ordinary high water mark or approxim ately 3 feet above the existing channel flow line, whichever is greater.
905.04 Method of Measurement
1.Rock which is accepted and used in the construction will be measured by the ton (Megagram). The weight will be determined by measuring the volume [cubic yards (cubic meters)] of riprap placed and multiplying by 1.35 ton/cubic yard (1.6 Mg/m3).
2.a. Quarry weight determinations will be accepted by the Engineer. The attendant at the quarry will issue tickets to the driver for each load of rock riprap delivered to the project.
b.Each ticket shall include: (1) The name of the producer.
2.The date.
3.The location of the quarry.
4.The quantity delivered [in tons (Megagrams)].
5.The name of the Contractor.
6.The project number.
c.The ticket shall be given to the Engineer at the time of arrival at the placement site.
3.When any shipment's weight has not been documented, the Contractor shall measure the rock on ap proved scales in the presence of the Engineer.
4.When shipped by rail, the measur ed shipping weight of acceptable material, less material that is wasted, will be used as the basis for payment.
905.05 Basis of Payment
1.P a y I t e m P a y U n i t Rock Riprap, Type _____ Ton (Tn) [Megagram (Mg)]
2.Energy dissipation hole excavation is subsidiary to the rock riprap bid item.
3.Placing and mixing of native soil in the riprap is subsidiary to the excavation or embankment item.
4.Payment is full compensation for all work described in this Section. - 734 - SECTION 906 -- BROKEN CONCRETE RIPRAP
906.01 Description
1.a. The Contractor shall prep are the slopes and place broken concrete on the earth slopes at the locations shown in the contract.
b.Any excavation or embankm ent necessary to place the riprap to the limits shown in the contract shall be part of this work.
2.The concrete riprap shall be ob tained from the areas designated in the contract.
3.a. It shall be the responsibility of the Contractor to ensure that a sufficient quantity of concrete be brok en to the requirements stated below and removed for use as riprap.
b.Any concrete intended but not used as riprap shall be disposed of as directed by the Engineer.
906.02 Material Requirements
1.a. The Contractor shall size the riprap by breaking the concrete rubble so that no individual piece wi ll have a volume greater than 3.5 cubic (0.1 m3) feet.
b.No more than 10% of the ri prap pieces shall have a volume of less than 30 cubic inches (0.0005 m3).
c.Fifty percent of the riprap shall be composed of pieces with a volume less than 1,220 cubic inches (0.02 m3).
d.Each piece shall have no dimension greater than 4 times its least dimension.
2.Control of the sizing shall be by visual inspection to verify that the concrete rubble is well graded and conforms to the maximum and minimum sizes specified.
906.03 Construction Methods
1.Grading a. The finished earth surface shall conform to the grades and slopes of the neat lines of the bottom surface of the riprap as shown in the contract.
b.Depressions shall be filled with suitable dry material which shall be thoroughly tamped or otherwise compacted to insure stability.
c.Soft, unstable materials shall be removed and replaced with suitable material which shall be thoroughly tamped or otherwise compacted to insure stability. No raised places, bumps, or depressions will be allowed.
2.The Contractor shall place the broken concrete so each piece is touching the adjacent pieces in a conf iguration creating the highest possible density while producing a stable mass within the limits shown in the contract.
3.All material shall be placed so that the large and small sizes are well mixed.
4.Reinforcing steel bars projecting from the mass shall be cut off flush with the face from which it protrudes.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 766–767 of 1,048.