The repair of Porphyry pavement is one of the benefits of using the stone. In this piece on repairing utility cuts we see there are some procedures to be followed, but when the repair is finished, there is no noticeable difference between the original and the repaired area, like there would be with asphalt or concrete.
In 2002, the Construction Practices Subcommittee of the American Public Works Association (APWA) was assigned to research available documents related to pavement degradation caused by utility cuts. A summary of the major findings of their literature review follows:
• Factors influencing the performance of a patch include the pavement material, soil conditions, climate, traffic and repair techniques. These roughly correlate with the same factors influencing the life of a new pavement.
• Poor construction techniques, such as rocking the jackhammer while cutting the boundary of the patch, can damage the area adjacent to the cut and further degrade the patch and surrounding pavement. Studies showed this zone of influence to be 1.5 to 6 feet beyond the patch.
• Pavement cut repairs made using quality materials and sound engineering and construction techniques tend to perform as well as the surrounding pavement.
• Poor performance of the patch tends to be a result of inadequate compaction of the materials, insufficient thickness of materials, poor quality of materials, and damage to the side of the cut.
• Most of the reports included a cost analysis associated with the cuts ranging from $2 per square yard to $540 per square yard.
• The estimated reduction in pavement life due to a utility cut was found to be from 20 to 56% of the original life of the pavement.
Dallas Street Repair Standards Manual
The drawing above is from the Dallas Street Repair Manual and includes variable thickness stone such as porphyry. The excerpt below is also from their document and details the critical need for particular attention to be paid to the base and sub-base in this type of repair.
“That portion of the backfill which lies more than 12 inches below and portion of any sidewalk, driveway, alley, or roadway or other pavement shall be compacted by mechanical compaction to a density of 95% of Standard Proctor density to minus 2% to plus 4% of optimum moisture of samples of the backfill material as determined by the ‘maximum density optimum moisture test’ as provided for in ASTM designation D698. If hand pneumatic tampers are used, the backfill shall be placed in layers not exceeding three (3) inches and thoroughly tamped in place.
In addition to the provisions above, the portion of the backfill which lies within 12 inches below any portion of any driveway or ‘improved’ roadway shall be compacted to secure a density of not less than 98% of standard proctor density to minus 2% to plus 4% of optimum moisture of samples of the material as determined by the ‘maximum density optimum moisture test’ ASTM designation D698. The backfill material shall be moistened when required to obtain satisfactory moisture content and compaction. If the flowable fill method of backfill is used, the flowable fill material shall be placed to the base of the pavement.”
Porphyry’s composition determines its high compression strength, resistance to stains, slip resistance, and high freeze/thaw ratings. The stone is the most popular paver in Europe, and is favored for its flexibility in design, beauty, durability and low maintenance requirements. ADA Compliant Porphyry pavers are also adaptable to a permeable paving set. The stone is by far one of the most durable pavers in the world. These materials are available from Milestone Imports. – www.milestoneimports.com