3-14 Section 304. Rubblizing Portland Cement Concrete Pavement
304.01 Description
This work consists of preparing, shattering, compacting reinforced or non- reinforced Portland cement concrete (PCC) pavement to provide a rubblized base, and disposing of surplus and deleterious material in accordance with subsection 205.03.P.
304.02 Materials
Provide material in accordance with the following section: Dense-Graded Aggregate 21AA ........................................................... 902
304.03 Cons truction
A.Equipment . Use a water sprinkling system to suppress dust generated by pavement shattering operations. For rubblizing pavement, use one of the following types of self -contained, self-propelled pavement breaking equipment:
1.Resonant frequency equipm ent producing a low amplitude breaking force; or
2.Multiple impact hammer equipment capable of lifting and falling in an independent, adjustable, random sequence with variable force of impact. If impact hammer equipment is used, the number and spacing of hammers may vary. Ensure that the weights of individual hammers do not destroy the integrity of layers within 24 inches of the bottom of the rubblized pavement.
B.Preparation Work. Before beginning pavement rubblizing, complete all of the following:
1.Saw cut a relief joint full depth where rubblizing abuts concrete pavement that is required to remain or that will be rubblized in a later stage;
2.Construct the pavement widening or shoulders to match the elevation of the adjacent pavement requir ing rubblizing ;
3.Complete the construction of drainage systems for the new pavement structures, including outlet endings. Backfill and compact to the existing grade to prevent damage to the drainage system ;
4.Remove pavement shown on the plans , or as directed by the Engineer, over utilities or pipes with less than 18 inches of granular MDOT Standard Specifications for Construction Section 304 3-15 material cover as measured from the bottom of the pavement to the top of the utility or pipe. Extend the limits for pavement removal 3 feet beyond each side of a utility or pipe. Backfill the removal area with filler aggregate in layers no greater than 6 inches, and compact as approved by the Engineer. Do not remove patching material until after rubblizing. Backfill the removal area with filler aggregate before compaction operati ons.
C.Quality Control Checks. Perform the following field checks and provide same -day documentation of the field checks to the Engineer:
1.At the start of and during rubblizing operations, establish, demonstrate, and document equipment capabilities, including speed and impact frequency.
2.At least once per lane and every 1, 500 feet, as determined by the Engineer, inspect the rubblized pavement to determine whether the rubblizing operation has debonded the reinforcement from the concrete and is achieving the part icle size specified in subsection
304.03 F. Perform the inspection as follows:
a.Mechanically excavate an area of 25 square feet through the full depth of the pavement, taking care not to further rubblize. Notify the Engineer at least 2 hours before excavati on to allow verification of results for acceptance.
b.If the Engineer directs, perform spot inspections to the top of reinforcement using manual methods instead of mechanical methods. The inspections may be at the locations listed above (subsection 304.03.C. 2) or at other locations chosen by the Engineer. Use a shovel or pick to excavate an area of 25 square feet. Use a geologist ’s pick or mason ’s hammer to separate the concrete pieces above the reinforcing mat. Remove as much material as possible and clean the remaining surface with a stiff -bristled broom or brush to expose the reinforcing mat. The Department considers the mat debonded if at least 80% of the mat is visible after excavation and sweeping.
c.If performing inspections using manual methods, sound the concrete below the reinforcing mat to determine if material is fractured.
d.Restore inspection sites with filler aggregate and compact. The Engineer may adjust the inspection frequency. MDOT Standard Specifications for Construction Section 304 3-16 3. Ensure that the completed rubblized surface has a uniform appearance with no unbroken strips of pavement, exposed reinforcement, or visible joint filler and asphalt patching material.
D.Compaction . Before placing t he HMA mixture, compact the rubblized pavement with vibratory steel -wheeled and pneumatic -tired rollers in the following sequence:
1.At least two passes with a Z -grid vibratory roller or steel drum roller as approved by the Engineer;
2.All subsequent passes w ith a pneumatic -tired or steel drum roller; except
3.The final pass just before HMA placement , which is with a steel drum roller. The Department considers a pass down and back in the same path. Provide rollers with a nominal gross weight of at least 10 ton s. Operate vibratory rollers in a high vibration mode and at a speed no greater than 6 feet per second unless otherwise limited by the condition of the base, subbase, subgrade, or drainage features. The Contractor may apply water if the Engineer approves. After compaction and before placing HMA, ensure that the finished surface varies no more than ±1 inch when tested with a 10-foot straightedge. Fill voids and depressions with filler aggregate and compact.
E.Miscellaneous. Do not allow vehicular traffic on the rubblized pavement before HMA placement unless otherwise required for construction and maintenance of traffic, as approved by the Engineer. Maintain the compaction of portions of the rubblized pavement with no exposed reinforcement for crossroad or ramp traffic. In part -width construction areas, rubblize the pavement to the limits of the required overlay for that stage. Saw cut the longitudinal joint deep enough to cut the tie bar unless rubblizing in a prior stage extended beyond t he centerline and past the tie bar. Do not damage items that are required to remain, including drainage structures and monument boxes.
F.Acceptance Criteria. The Engineer will observe quality control checks described in subsection 304.03.C and base acceptanc e on the following criteria:
1.PCC pavement shattered to full depth; MDOT Standard Specifications for Construction Section 304 3-17 2. Non-reinforced PCC pavement and concrete pavement patches reduced to unbound particles with diameter s less than 10 inches;
3.Reinforced PCC pavement and concrete pavement patches above the reinforcement reduced to unbound particles with a nominal diameter from 2 inches to 6 inches;
4.Reinforced PCC pavement and concrete pavement patches below reinforcement exhibit sporadic particles greater than 10 inches, provided the Engineer verifies debonding of reinforcement near the particle;
5.No oversized particles at the surface for PCC pavements;
6.Debonding of reinforced pavement achieved if the required particle size is met;
7.Exposed reinforcement has been cut off below the surface and removed. Embedded reinforcement may remain in place;
8.No visible joint sealant or asphalt patching material on the compacted surface , and voids filled with filler aggregate;
9.Joints and cracks greater than ¼ inch wide at the surface are not distinguishable; and
10.No displacement of underlying base, subgrade, or underdrains.
304.04 Measurement and Payment
Pay Item Pay Unit Pavt, Rubblize ............................................................................... Square Yard Aggregate, Filler .......................................................................................... Ton Saw Cut, Rubblize ..................................................................................... Foot
A.Pavt, Rubblize . The unit price for Pavt, Rubblize includes the cost of the following:
1.Required quality control work ;
2.Rubblizing ;
3.Dust suppression, including water ;
4.Removing joint fillers and patching materials ;
5.Cutting exposed steel, loading, hauling, and disposing of the steel and immediate restoration of disturbed rubblized concrete;
6.Breaking down or removing and disposing of oversized pavement pieces ; MDOT Standard Specifications for Construction Section 304 3-18 7. Disposing of material removed from inspection areas ; and
8.Maintaining the condition of the rubblized pavement until placement of the HMA pavement .
B.Aggregate, Filler . The unit price for Aggregate, Filler includes the cost of producing, delivering, placing, leveling, and compacting the aggregate in rubblized pavement .
C.Saw Cut, Rubblize. The unit price for Saw Cut, Rubblize includes the cost of cutting a relief joint full depth where the rubblizing abuts concrete pavement that is required to remain or is removed for other purposes and cutting the longitudinal joint thr ough the tie bars where necessary. The Department will pay for concrete pavement removal separately as Pavt, Rem in accordance with section 204.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 189–193 of 1,146.