The winter freeze-thaw cycle is asphalt’s arch enemy.
UDOT crews are out in full force this time of year doing their best to stay ahead of pothole proliferation. Because of the way they are formed, repairing the dastardly dips can be a real challenge.
From the bottom up
Usually a pothole starts when water seeps into a crack in the asphalt to the soil below. As ice forms in the water-saturated soil, the area expands and causes the asphalt to heave and crack even more. Warmer temperatures melt the ice and relax the soil and asphalt. The final blow comes when the weight of traffic causes the asphalt to cave in and form a pothole.
Traditional repair involves using asphalt to fix the pothole. Hot asphalt is the best repair because it seeps into the cracks and bonds well with the old material, but cold winter temperatures prevent its use.
Cold mix asphalt is stockpiled at UDOT maintenance sheds and used to fill potholes during winter months. Sometimes a fix works well, but sometimes, the repair pops out during the next freeze-thaw cycle.
” When using cold mix, it’s a temporary repair until we are able to go in and square out the hole and fill and compact with hot mix,” says Todd Richins, Area Supervisor at UDOT Region Two.
New hot and cold repairs
UDOT is actively seeking longer lasting repairs, and maintenance engineers have found some promising options.
A new hot method heats the existing asphalt so it can be mixed with
additional asphalt and then compacted. This hot repair method was tested on a notorious pothole on I-84 at Echo Junction in December 2009.
According to Richins, the repair is still intact. UDOT maintenance workers are putting it into use in other appropriate locations.
An easy to use patch in a bag method has also been tried on an I-15 bridge in Santaquin. The mix consists of asphalt and polymer, and it’s designed to instantly bond with the old material when poured directly on a crack or pothole. UDOT Maintenance trucks can sometimes be the method of compaction.
Winter cold mix repairs in this area on I-15 usually lasted a week or two at most, but this pour and pack repair has lasted a year without failing with workers adding more material as needed.
“It works really well, and we’re using it in a lot of places,” says Glen Wahlberg, Area Supervisor in Region Three. “We love it.”
UDOT will continue to look for longer lasting repairs that defy, for as long as possible anyway, Utah’s winter freeze-thaw weather cycles.
Want to know where the term “pothole” comes from? Follow this link to learn more about potholes.