Agencies have three main costs for pothole patching: material, labor and equipment.
The cost of purchasing material is one of the most common focus points, but the least significant factor to the overall patching operation. (Strategic Highway Research Program, SHRP-H- 348).
Stay-in-place capability will significantly impact the frequency of re-repairs and overall maintenance costs; replacing a pothole just once doubles the cost. Some potholes are re-repaired on a weekly basis.
Anyone can combine asphalt with rock, and any combination can be marketed as equal. Design for permanent performance, or design for temporary performance – producer’s/buyer’s choice. Temporary designs will not perform like UPM. The most common position is “Cold mix is cold mix, equivalent to UPM “. This is far from the truth and unsupported by analysis or controlled performance testing.
The secret is the process: controlling aggregate, asphalt, additives and manufacturing. An asphalt film on the rock makes the rock black; having the optimum film makes it permanent. Surface area, one of the most critical parameters, determines the amount of asphalt and additive to achieve optimum rock to rock cohesion and cold mix to pothole wall adhesion.
Consistent performance can only be achieved through testing, design and control. Like HMA, the better the design and QC the longer lasting the road.
Installation contributes to overall performance, therefore, installation methods and training should be a incorporates into every maintenance program.
Those interested in lowering total maintenance costs should approach pothole repair as permanent and not as a temporary fix. Eliminating reappearing pothole repairs creates an opportunity to repair more potholes with identical resources resulting in increased service to the community.