2-29 Section 260
260-1 Description
Furnish and operate at the direction of the Engineer, heavy pneumatic tired compaction equipment for compacting the roadbed and testing the roadbed for stability a nd uniformity of compaction.
260-2 Equipment
Provide equipment with the following features:
A.Four rubber tired wheels mounted on a rigid steel frame ,
B.Wheels evenly spaced in one line across the width of the roller and arranged so that all wheels will carry approximately equal loads when operated over an uneven surface ,
C.Maximum center to center spacing between adjacent wheels is 32 inches ,
D.Load capacity from 48 to 50 tons unless otherwise permitted in writing ,
E.Cover or construct t he loaded roller to not trap water that will add weight to the ballast,
F.Other equipment of equal or better effectiveness may be substituted with written permission , and
G.Tire pres sures shall be between 68 and 72 psi unless otherwise permitted in writing. Inflate tires with air only; use no liquid. Provide ballasts consisting of bulk sand, bulk stone, bags of sand, stone or other materials of known unit weight such that the total weight of the ballast used can be readily determined at all times. Have a sufficient amount of ballast available on the j ob site to load the equipment to a maximum gross weight of 50 tons. Use rubber tired or other types of tractive equipment for operation of this equipment on the roadbed. The entire assembly including motivating equipment shall be capable of executing a 180° turn on a 27 feet wide area.
260-3 Construction Methods
After the roadbed has been completed within 0.5 feet of final grade, compact and test the roadbed with one coverage, unless otherwise directed by the Engineer , with a heavy pneumatic tired roller in accordance with Article 260-2. Coverage is considered that stage in the rolling procedure when the entire width of the area being proof rolled has been in contact with the pneumatic tires of the roller. Operate the roller systematic ally so the number of coverages over all areas to be proof rolled can be readily determined and recorded. Operate the equipment at a speed between 225 feet per minute and 300 feet per minute. Perform proof rolling only in the presence of the Engineer. Proof roll areas again following the co mpletion of the necessary corrections. Protect all structural facilities on the project, such as , but not limited to , bridges, box culverts, pipe culverts and utilities, from damage by the proof rolling equipment. Protection may include unloading and reloading of the roller, detouring, protective earth pads or other suitable measure to avoid damage.
260-4 Measurement and Payment
Proof Rolling will be measured and paid as the actual number of hours, measured to the nearest 0.1 hour, during which the heavy pneumatic tired roller has been engaged in proof rolling in the presence of the Engineer, exclusive of hours of proof rolling performed following corrective action made necessar y by the negligence of the Contractor or by weather.
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 121–121 of 857.