- 420 - SECTION 604 -- CONCRETE BASE COURSE
604.01 Description
1.This work shall consist of furnishing all materials and constructing a base course composed of Portland cement concrete. It shall be constructed on a prepared subgrade or foundation c ourse as shown in the contract.
604.02 Material Requirements
1.The base course concrete shall be Class 47B-3,000 (47B-20)
2.All materials shall be furnished by the Contractor and shall conform to the requirements in Table 604.01. Table 604.01 Material Requirements Applicable Materials Section Portland Cement Concrete ........................ 1002 Joint Sealing Filler ..................................... 1014 Preformed Joint Filler ................................. 1015 Reinforcing St eel ....................................... 1020, 1021, 1024 Deformed Metal Join t Material ................... 1027 Curing Materi als......................................... 101 0, 1011, 1012, 1013 Dowel Bars ................................................ 1022 Aggregates ................................................ 1033 Admixtures ................................................. 1007 Water ......................................................... 1005
604.03 Equipment
1.The equipment used and the calibration responsibility shall be as described in Sections 601 and 603.
604.04 Construction Methods
1.The Contractor shall prepar e the subgrade and foundation course as described in Sections 30 1, 302, 303, 305, and 307.
2.Concrete base course shall be constructed in accordance with the pertinent sections of Section 603.
3.The surface of the concrete base course shall be tested for smoothness in both the transverse and long itudinal directions with a 10 foot (3 m) straightedge. The maximum allowable variation is 1/4 inch (6 mm). Base course not meeting this requirement will be evaluated by the Engineer and may be subject to corrective diamond grinding or other remedy.
4.a. When a bituminous or asph altic concrete surface is to be placed on the base course, a bituminous liquid curing compound conforming to the requirements of Se ction 1013 shall be applied.
b.The rate of application shal l be determined from the results of moisture retention tests, except that the rate of application shall never be less than 1 Gal/200 SF (2 L/m2) of surface area.
c.In the event that the cure coating is damaged within 72 hours after being applied, the affected areas sh all be recoated without delay at the same rate described for the original application.
5.a. The base course may be opened for hauling and placing the wearing or surface course after the concrete has cured 14 days or after Concrete Base Course 604.06 - 421 - 7 days with the pavement having developed a compressive strength of 3,000 psi (20 MPa) when tested in accordance with ASTM C 39.
b.The Engineer shall be given 48 hour notice before any vehicles are allowed on the pavement.
6.The Contractor shall clean and s eal all cracks and joints in the base course with approved joint sealer if the wearing or surface course is not placed during the same construction seas on as the base course. This work is subsidiary to the Concrete Base Course.
604.05 Method of Measurement
1.Concrete base course is measured by the square yard (meter).
604.06 Basis of Payment
1.P a y I t e m P a y U n i t _____ Concrete Base Course; _____ Square Yard (SY) [Square Meter (m2)]
2.Deductions for str ength deficiencies will be computed as described in Section 603.
3.Welded steel wire fabric reinforcing used in the concrete base course will not be paid for directly but shall be considered subsidiary to concrete base course.
4.Furnishing and placing the required reinforcement and dowel bars in the concrete base course will not be paid for directly but will be considered subsidiary to the concrete base course.
5.If varying types or thicknesses of concrete are used, the pay item will be subdivided to show the quantities of each variation.
6.a. The 28-day compressive st rength of each day's production unit will be determined from cy linder strength tests.
b.Payment shall be reduced by the amount described in Table 603.03.
c.(1) If the first 28 day compressive strength fails, the Contractor has the option to take 3 core samples, at no additional cost to the Department and under the supervision of the Engineer. The Department will take immediate custody of the cores at the time of sampling. The average compressive strength of these cores will be used to determine the actual 28-day compressive strength of each day's production.
2.Cores shall be taken and tested within seven (7) days of being notified of the strength deficiency.
3.The Engineer will select the location where the cores will be taken within each day’s production unit.
7.Payment is full compensation fo r all requirements described in this Section. - 422 - SECTION 605 -- CONCRET E PAVEMENT REPAIR
605.01 Description
1.This work shall consist of repairing Portland cement concrete pavement at the locations shown in t he contract or as designated by the Engineer. The work shall include removing deteriorated concrete, disposing of the old concrete, preparation of the repair area, and furnishing, placing, finishing, and curing the concrete.
2.Concrete pavement repairs are grouped into 3 types based on the surface area of the patch (see Table 605.01). If a concrete repair extends across more than one lane, the repairs in each lane will be counted as a separate repair. Table 605.01 PCC Pavement Repair Groups Type Size Square Yards or m² A Less than 5 B 5 to 15 C More than 15
3.Full width concrete pavement repairs shall be a minimum of 4 feet (1.2 m) in length.
4.Removal of concrete for partial depth pavement repair shall be to the depth necessary to reach sound concrete. The minimum depth of removal shall be 3 inches (75 mm), or as shown in the contract.
5.Full depth pavement repair s hall be constructed on a prepared subgrade or foundation course as describ ed in the contract. The thickness of the new concrete pavement will be as shown in the contract, or 2 inches thicker than the adjacent pavement, if not shown in the contract.
6.a. When performing concre te pavement repairs on 2-lane roadways, the Contractor shall have a ll lanes open to traffic before sunset and at times when the Contractor is not working. Where the pavement has been removed and the Contractor is unable to complete the required patching in time for the concrete to obtain the full curing time required prior to opening the section of the road to tra ffic, the excavation shall be filled with a commercially available cold-mix bitu minous mixture, or other suitable temporary patch material with a durable surface. The Contractor will be required to maintain traffic flow across these patches while they are in service. When it is necessary to us e a temporary patch, the patch shall be removed, and the required permanent patch placed, within 48 hours unless otherwise directed by the Engineer. The temporary patches will be at no cost to the Department.
b.When performing concrete pavement repairs on multi-lane highways, the Contractor may have one lane closed while performing the repair work. Repairs shall not be left open overnight. Where the pavement has been removed, and the Contractor is unable to complete the required patch before sunset, the Contractor sha ll fill the excavated area with either:
1.the appropriate patching concrete material for curing overnight, or (2) a suitable material with a durable surfac e. The material, installation, removal and disposal of these temporary patches will not be measured and paid for
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 454–455 of 1,048.