- 451 - SECTION 701 -- GENERAL REQUIREMENTS
701.01 Description
1.This Section describes proc edures and equipment that are common to a variety of structures as described in Division 700.
701.02 General Procedures
1.The Contractor shall excavate and place shoring as necessary to insure safe access to work areas.
2.Concrete Proportioning: a. Concrete shall be proportioned, mixed and delivered under inspection of the Engineer.
b.A copy of the concrete load tickets shall accompany each load to the placement site and be availabl e to the Engineer. Acceptance of the concrete at the placement site will be partially based upon verification that the concrete is of the proper class and has been delivered within the specified time limits.
c.Loads which are not accompanied by such tickets, which do not arrive in satisfactory condition, or which do not arrive within the specified time limits shall be rejected.
3.When unsuitable material is encountered, it shall be removed. Excavation will continue until the unsui table material is removed or until the Engineer halts excavation.
4.When a concrete bottom seal course is required due to unforeseen conditions, the excavation shall be su fficient to allow for placement of the seal under the structure.
5.The Contractor shall not excavate within 5 feet (1.5 m) of any cast- in-place concrete deadman or grade beam tie rod anchor except for the limits of tie rod trenches and granul ar backfill as shown in the granular backfill details.
6.Concrete Placement and Consolidation:
a.Concrete shall be placed and consolidated in its final position with the utmost care.
b.The method used to place concrete shall not allow the concrete materials to segregate or displace reinforcing steel.
c.The impact of any free fall s hall be kept to the lowest levels consistent with efficient placement.
d.The maximum free fall plac ement distance shall be 5 feet (1.5 m).
e.The use of vibrators to mo ve concrete shall be prohibited.
7.The Contractor shall backfill bridge abutments, wingwalls, and retaining walls concurrently on all sides.
8.Cofferdams: a. Cofferdams shall be substantially watertight. The interior dimensions of cofferdams shall be such as to give sufficient clearance for the construction and inspection of forms.
701.02 General Requirements
- 452 - b. Cofferdams shall be constructed so as to protect recently placed concrete from damage from a sudden rising of water and to prevent damage to the foundation by erosion.
c.No timber bracing shall be left in cofferdams or cribs. No bracing shall be incorporated into the structure's concrete.
d.Cofferdams shall be remov ed by the Contractor after the completion of the substructure.
9.Blocks and bracing shall be removed with the forms, and in no case shall any portion of the forms be left in the concrete.
10.Water jetting is not authorized for excavating or backfilling around structures.
701.03 Equipment
1.On bridge decks, jackhammers are restricted to those lighter than the 60 lb. (30 Kg) class.
2.Jackhammers or chipping tools shall not be operated at angles greater than 45 degrees from the deck surface. - 453 - SECTION 702 -- EXCAVATION FOR STRUCTURES
702.01 Description
1.Bridges and the steel/concrete st ructures specified in Division 700 may require excavation as part of their construction, and this excavation is distinguished from the roadway excavati on specified in Section 200. This work shall consist of all excavation for the following:
a.Bridge foundations: (1) Abutments. (2) Piers. (3) Bents.
b.Concrete seals.
c.All culverts. d. Structural plate pipe. e. Headwalls and wingwalls. f. Retaining, MSE and Modular Block walls. g. Steps. h. Any and all other structures described in Division 700 or shown in the contract.
2.This work shall include the re moval of any obstructions within the excavation limits shown in the contract. It shall include all necessary bailing, draining, pumping, sheathing, and the construction of cofferdams or temporary cribs and their subsequent removal. The work shall also include backfilling, compacting, and the dispos al of any excess material obtained from such excavation.
3.All excavation shall be performed in compliance with current OSHA standards.
702.02 Material Requirements
1.Backfill materials shall be approved by the Engineer. 2. "Granular Backfill" meeting the requirements specified in Subsection 1033.02, Paragraphs 1., 2., and 3. or 6. and the requirements in Tables 1033.02A, 1033.03A or 1033.06 will be acc eptable. "Clay lump" and "mortar-making" proper ties do not apply.
702.03 Construction Methods
1.Substructure Excavations:
a.The Contractor shall excavate a volume large enough to contain the structure an d its forms and provide access to set, strike, and inspect the work (18 inch (450 mm) la teral spacing is generally adequate access).
b.Footings on soil: (1) If water is encountered, the Contractor shall dewater the excavation.
2.The water level shall then be maintained at an elevation below the base of the excavation until after the concrete has been placed and set for at least 5 hours.
Referenced in this section
GENERAL REQUIREMENTS in other states
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Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 485–486 of 1,048. View official source ↗