Utility Trench Asphalt Removal: Saw-Cutting or Asphalt Grinding?
Every utility trench project has asphalt removal at the beginning of the job and road patch repair at the end. Utility contractors commonly remove asphalt from the paved surface with saw cutting, asphalt grinding, or asphalt milling techniques.
Saw cutting involves cutting the asphalt into chunks, loading in on trucks, and hauling it away. Asphalt grinding uses a cold planer, asphalt grinder, or asphalt milling machine to pulverize the asphalt.
Many projects use the asphalt grindings as trench backfill, but some project specs don’t consider it proper backfill. If this is the case, contractors can store the asphalt grindings to use as trench backfill for future jobs.
Utility Trench Pavement Patching
At the end of a utility trench project, it is important to patch the asphalt surface. This involves filling the trench with backfill material, compacting it well to avoid trench settling, and new asphalt pavement.
Good pavement patching ensures that the road remains structurally sound. If you have your own asphalt grinding machine or cold planer, you can do your asphalt removal in house.
There are many benefits to doing asphalt milling in house. Some contractors complete an entire section of utility trench in one day. First they use their asphalt grinding machine for pavement milling on a specific length of trench.
Next they excavate the pipe trench and replace the pipe, fill and compact the trench, and pave over in one day. This keeps traffic disruptions to a minimum.
Even the Best Pavement Patch Weakens the Asphalt and Road Base
Even with the best possible road patch practices, pavement patches still weaken the asphalt and surrounding areas. Road settling is a major factor in road patches weakening. Different materials for trench backfill and road base could have different settling rates or load bearing capacities, causing potential stress points.
Temperature fluctuations can also affect road patch integrity. If the road base and the trench backfill expand and contract at different rates, they further weaken the road surface. Additionally, moisture in the pavement joints causes more weakness.
Better Road Patch Integrity with T-section or Bridge Patching
T-section or bridge patches are more durable utility trench patches. They extend the asphalt patch beyond the trench edges forming a bridge or “T”. The asphalt grinder mills a few inches into the existing asphalt pavement on each side of the utility trench.
The asphalt grinder then grinds the full depth of the pavement over the utility trench. After replacing the utility line, crews add trench backfill and compact. Finally they pave over both the trench and the shallower asphalt cut on each side.
The t-section or bridge asphalt patch looks like a “T.” The shallow asphalt on each side and deeper asphalt down the middle distributes the load more evenly and reduces stress concentration. By creating a bridge effect, the new patch creates stronger pavement.
Bridge Patches Prevent Joint Weakness
Every utility trench pavement patch has a joint where the original pavement and the patch meet. Because T-cut patches stagger pavement joints in layers, they avoid weakness across one joint. This distributes the stress, leading to a stronger and more resilient road patch.
T-cuts Prevent Moisture Damage
Because the t-cut joints are at different levels, moisture can’t seep into the entire joint. This reduces the risk of moisture at deeper layers, especially during freeze and thaw cycles. T-cut joints prevent moisture damage in pavement patches over utility trenches.
When to Use a T-patch or Bridge Patch
Some utility trench projects require t-patching. If there are no specific requirements, several factors determine whether or not to use a t-section patch.
A t-cut patch is more expensive because of the additional asphalt removal and asphalt patching. A t-section patch might not be worth it if the road has scheduled asphalt maintenance. On the other hand, a t cut patch will be more durable, limiting future repairs.
Using an Asphalt Grinder for T-cut Asphalt Removal Saves Time and Money
Using an asphalt grinder or cold planer for asphalt removal saves time and money, especially with bridge or t-cut patches. Asphalt grinding machines have precise asphalt milling depths. This allows for shallow cuts on each side and full depth asphalt removal in the trench.
An asphalt grinder or cold planer on site streamlines the utility trenching process. This allows you to cut only the pipe trench you need each day. Many project specs also allow using the asphalt millings as trench back fill. All of these factors give you budget and time flexibility on your utility trench project.