​Paving & Surface Treatments

The Infrastructure Department provides repair services to Thornton's streets. Such repairs may include potholes, crack sealing, street failures, and unimproved road grading.

Street Rehabilitation Program

The project includes rehabilitating city streets as determined by the Pavement Management System and staff recommendations. Rehabilitation includes asphalt overlays, crack seal, hot chip seals, street concrete replacement (curb, gutter, cross-pans), and accessible ramp replacement as required. Both city crews and contractors participate in the Street Rehabilitation treatments and locations. Project locations are shown on the map under featured links.

Concrete Replacement Program  

 City Council has approved a $ 140,000-a-year budget to replace broken or damaged concrete within the city. The severity of damage determines locations for replacement as they relate to pedestrian hazards, structural damage, surface deterioration, and impact on drainage. Work generally begins in March, weather dependent, and can last several months. 

Crack Seal

Why does my street crack?

Cracks can form in asphalt pavement through various modes of distress. Regardless of how the cracks form, they must be repaired to help protect the pavement structure. If the cracks are not maintained, they can ravel and increase in size. Unsealed cracks allow water to penetrate the structure from the pavement surface, which eventually causes potholes and further deterioration. Water infiltration is the number one enemy of pavement. Crack sealing is the most important and cost-effective maintenance option to help protect the integrity of the pavement.

Benefits of Crack Seal

  • Prevents water from entering the pavement and sub base

  • Prevents debris from entering the crack

  • Prevents or delays pothole formation

The life expectancy of Crack Seal is approximately 3-5 years.

Crack Seal Program

The Street Rehabilitation Program has developed a city-wide crack seal program that addresses every street in the City every five years. A contractor applies this crack seal. Street Operations also uses crack seals as needed in areas of safety concern (crosswalks, for example). After each crack seal application, the area is evaluated for mastic application. Mastic is a crack fill application that addresses cracks with a deflection that impacts the drivability of the roadway.

Hot-In-Place Recycling

Hot-In-Place (HIP) recycling is a single-pass repaving process using specially designed equipment in a simultaneous, multi-step process that removes some of the existing asphalt, reheats and recycles it with a rejuvenating agent and then is placed on the road surface with additional new Hot Mix Asphalt set on top of it. This process provides a smooth, restored riding surface.

Benefits of Hot-In-Place Recycling:

  • Improves the smoothness, durability, and appearance of the street with like-new results

  • Minimizes traffic delays because of its single-pass process

  • Environmentally friendly by reusing existing asphalt

HIP recycling has a life expectancy of approximately 8-10 years.

Hot In-Place Recycling: This option is used instead of a typical Mill and Overlay operation. The city of Thornton uses this process on all asphalt street types (Arterial, Residential). A benefit of using this process on residential roads is the minimal impact on residents. The HIP is a shorter paving process that allows residents to return to their streets sooner.

Hot Chip Overlay

Hot Chip Overlay is a two-step surface treatment combining a Chip Seal and a thin overlay of open-graded friction course (Hot Chip Seal) providing a double material application. This provides a waterproof membrane, and the Hot Chip Seal provides a strong wearing surface that will improve the profile of the existing asphalt.

Benefits of Hot Applied Chip Overlay:

  • Improves skid resistance and safety with a high-friction surface

  • Provides asphalt pavement with additional structural strength

  • Quiet surface treatment especially on high-volume traffic roads

  • Enhances the appearance of the road by improving the surface texture, profile, and surface color

Hot Chip Overlay has a life expectancy of approximately 8-10 years.

Since the Hot Chip Overlay is a two-step process, it will leave the road bumpy at points during its construction, and slowing down is the best thing drivers can do until the final overlay is applied in the second step of the process. During the Chip Seal process, drivers may encounter loose rock and should give extra distance to the car in front to avoid being struck by the loose material.

Asphalt Rejuvenator

Asphalt Rejuvenator is a liquid product sprayed on the road, rehydrating the asphalt binder (black stuff) that holds in the aggregate. By rehydrating the asphalt, binding the roadway will lose less aggregate and result in fewer potholes. Rejuvenators can be thought of as having the same results as a lotion for skin.

Benefits of Rejuvenators:

  • Cost-effective preventative maintenance treatment

  • Holds the aggregate in the roadway

  • Tightens and closes hairline cracks in the asphalt

  • Reduces potholes and large cracks

Asphalt Rejuvenator has a life expectancy of 5-7 years

Asphalt Rejuvenators are typically applied to Residential streets, and have a quick application time minimizing impact to residents.

Asphalt Mill/Pave

An asphalt mill/pave operation is the application where the top layer of asphalt is removed and replaced with new Hot Mix Asphalt (HMA). HMA is mixed, placed, and compacted at elevated temperatures, hence the name. HMA combines approximately 95% stone, sand, or gravel bound together by asphalt cement, a product of crude oil. Asphalt cement acts as the glue to hold the pavement together. The resulting Hot Mix Asphalt is loaded into trucks for transport to the paving site. The trucks dump the Hot Mix Asphalt into hoppers at the front of paving machines. The asphalt is placed and then compacted using a heavy roller, which is driven over the asphalt. Traffic is generally permitted on the pavement as soon as the pavement has cooled. 

Asphalt is America's most recycled material. The city of Thornton's HMA contains approximately 20% recycled asphalt. Recycling is just one reason that asphalt is such a sustainable pavement.

Benefits of Hot Mix Asphalt Mill/Pave:

  • Less expensive than complete removal and replacement

  • Removes surface damage to street

  • Can improve drainage in streets

  • Re-establishes proper grade

  • Improves surface for smoother driving and better traction

HMA has a life expectancy of approximately 10-15 years, depending on the traffic volume.

Asphalt Base Patching with Geogrids

The city of Thornton utilizes a base patching with Geogrid textiles in its Street Rehabilitation Program to reduce the amount of deep cracking in asphalt pavement. This process includes milling (removing) an additional 3"+ of asphalt and placing a Geogrid textile mesh over the deep crack; the area is then backfilled with new Hot Mix Asphalt, and a wearing course (see above) is then applied over the entire street.

Benefits of Asphalt Base Patching with Geogrids:

  • Dramatically reduces the amount of reoccurring cracks

  • Stabilizes the bottom layer of the roadway

  • Provides longer life for the wearing surface course

Asphalt Base Patching with Geogrids combined with a surface-wearing course has a life expectancy of approximately 7-10 years, depending on the traffic volume.