304 - Rubbilizing Existing PCC Pavement
This work will consist of rubblizing existing concrete pavements to be used as a base course for Hot Mix Asphalt (HMA) pavements.
Equipment will be as listed in subsection 304.03 of the Standard Specifications for Construction. The existing pavement condition will determine the size of the shoe the Contractor will be able to use on the resonant frequency pavement breaking machine. If the pavement is demolishing easily and with little oversize, a wider shoe could possibly be used.
Filler aggregate will meet the Open-graded Aggregate 3G Specification, Section 902 of the Standard Specifications for Construction.
Inspector’s Daily Reports should be used to report quantities of work completed daily. The actual width of the pavement and plan width of the pavement should be compared to make sure they agree. The inspector should note the beginning and end station daily to complete the Inspector’s Daily Report.
The inspector should study the staging details very carefully. In situations where the road must be reopened for traffic, the rubblizing Contractor and paving Contractor should coordinate these efforts so any area open to traffic has at least an initial leveling course (scratch course) placed daily.
Where the existing pavement is composite (HMA over concrete), the inspector should closely monitor the cold-milling operation making sure the existing HMA has been completely milled off.
Placement of the drainage system (most often Prefabricated Drainage System) should be clarified with the Contractor. Emphasis should be placed on both grade and outlet. The roadway typical cross section should specify the grade placement of the drainage system relative to the existing slab. Outlet placement will be determined by the existing roadway terrain. It is essential to have the drainage system in place and working prior to rubblizing as the process tends to encourage migration of water into rubblized material.
The inspector should take care at cross culverts. The drainage system should be checked for clearance over the culverts. If no clearance can be obtained over the culverts, the drainage system will need to be interrupted and an outlet will probably need to be placed.
Particular attention should be paid to the amount of water that is applied in the rolling process. The compaction effort is specified by the Rolling Pattern in the Standard Specifications for Construction. The inspector and Contractor should work together and determine the proper number of water units to apply to aid in the compaction effort, but not saturate the existing grade. The inspector should also pay close attention to the rubblizing making sure there is not excessive oversize material [less than 6 inches (150 mm) is the greatest dimension]. The oversize material will have to be removed or reduced to smaller diameter particles with a jackhammer or similar device.