305 Portland Cement Concrete Base

Construction (305.02)

When constructing this item, the requirements of 451 apply with the following exceptions:

  1. Reinforcing mesh required by 451.08 is not required in concrete base.
  2. Provide dowels at transverse contraction joints in mainline pavement, ramps, acceleration/deceleration lanes, or collector/distributor lanes. Dowels are not required in shoulders for mainline pavement, ramps, acceleration/deceleration lanes, or collector/distributor lanes unless the transverse contraction joint is located within 500 feet of a pressure relief joint.
  3. Construction joints are not to be placed within 6 feet of another parallel joint.
  4. The curing application rate for the membrane forming, curing compound for concrete base is 200 square feet per gallon (5 square meters per liter) instead of what is specified for 451 and 452 pavement described in 451.11.
  5. The surface finish for concrete base is broom dragged in either the longitudinal or the transverse direction to provide a uniform, gritty surface texture to the satisfaction of the Engineer. Tining per 451.10 is not required.
  6. Surface smoothness variations for concrete base are not to exceed 1/4 inch in 10 feet (6 mm in 3 m).
  7. Station numbers as required in 451.10 are not required for concrete base.

 

Method of Measurement (305.03)

The concrete base must be field measured and the area of pavement placed be calculated for payment in square yards (square meters). The area is determined the same as 451 or 452 pavement.

The pavement width for payment will be based on the plan typical cross-section, plus any additional widening that has been directed by the Engineer. The length will be field measured along the centerline of the roadway or ramp.

Determine thickness of the base conforming to 451.18.A.

 

Basis of Payment (305.04)

Pay a reduced price for base found deficient in thickness according to 451.19.A. There is no additional payment for a concrete base thicker than that shown in the plans. Pay for accepted quantities at the Contract price per square yard (square meter).

 

Documentation Requirements - 305 Portland Cement Concrete Base

  1. Document subgrade/subbase preparation.
  2. Document contraction, expansion, and longitudinal joints dowel as well as tiebar sizes, type, coating, support, placement, and spacing.
  3. Document forms set 100 percent bearing, correct alignment and grade, rigid, clean, and oiled.
  4. Document length of lap and clearance maintained on steel mesh.
  5. Document contraction joint spacing, dowels oiled, dowel assembly tie wires removed, number and size of pins used to hold dowel assembly, and alignment of dowels.
  6. For slip form construction document:

         Test section results.

         Approval of slip form paver.

         Alignment of dowels using MIT Scan-2.

         Corrective action as required.

  1. Document concrete placement including all quality control testing, method of placement, finishing, curing (type and amount), and weather conditions.
  2. Document use of HIPERPAV software, time of sawing, and depth and width of sawed joints.
  3. Document coring for thickness verification and results.

10.  Record results of beam breaks and opening to traffic.

11.  Measure length and width for pay.

12.  Document on CA-D-3A or CA-D-3B or other approved forms.