San Francisco International Airport


Location - San Francisco International Airport

URETEK USA was brought in to resolve a pavement preservation problem at one of the major airports in Northern California, San Francisco International Airport. Due to the high volume of aircrafts departing and landing, parts of the 10R-28L asphalt runway were beginning to reach end of life. FAARFIELD, a remaining life pavement analysis, was performed, and the results indicated that action was necessary to restore the pavement to an acceptable remaining life. This information, along with geotechnical field testing, was used to develop a solution.

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These remarkable results were supplemented with a post injection DCP test to compare to the pre-injection DCP test. It can be seen in side by side comparison that the single digit blowcounts (orange) were improved tremendously.”

Solution

Full depth repair was impractical due to the extended length of runway down time required to complete this traditional repair method, so other alternatives were investigated. Because of the proposed cost and time savings, San Francisco Airport engineers chose to use URETEK’s Deep Injection (UDI) process to stabilize the subgrade below the pavement and fill voids between the Cement Treated Base (CTB) and the subbase, coupled with a mill & overlay to remove weakened asphalt and create a smooth pavement surface.

URETEK USA used Dynamic Cone Penetrometer (DCP) tests to determine areas of void between the CTB and the subbase which varied throughout the length of the runway. The DCP tests also revealed a very weak saturated layer of soils down at approximately -8’. The injection plan involved shallow injections wherever void was detected and injections down at -10’ to help stabilize the weak subgrade.

URETEK USA hired Dynatest Consulting to perform Heavy Weight Deflectometer (HWD) testing and back calculation of the deflection results to determine Resilient Modulus (material stiffness) values for pre-treatment and post-treatment conditions. HWD testing was also performed in control areas where no polyurethane injections were performed. 

Why URETEK?

Time Savings
  • 90% faster than competitive solutions
  • Project work completed in hours / days versus weeks / months
  • Fast installation, curing and cleanup
Minimal Disruption
  • Minimizes or eliminates work zone delays
  • Work often done during off peak night time hours
  • Crews dismantle and remove work zones as they finish daily
Cost Savings
  • Up to 75% less than replacement cost
  • 2-Year unconditional warranty against settlement
Predictable Results
  • 100,000 successful projects worldwide
  • Precision adjustment to 1/8″
  • Hydro- insensitive – displaces under pavement water
Safety
  • Clean, organized worksite
  • Professionally trained & certified employees
  • Environmentally safe, inert product

Results

San Francisco experienced record rainfall between the pre-injection and post-injection testing which showed up in the control area data – on average the subgrade modulus worsened 18.7% and the CTB modulus worsened 34.7%. In significant contrast, the subgrade modulus and CTB modulus in the areas injected with polymer improved by an average of 15.7% and 21.1% respectively.
15.7%
Subgrade
Improvement
21.1%
Subgrade
Improvement
These remarkable results were supplemented with a post injection DCP test to compare to the pre-injection DCP test. It can be seen in side by side comparison that the single digit blowcounts (orange) were improved tremendously. The same pavement remaining life analysis (FAARFIELD) was performed following the polymer injections with mill & overlay and indicated a pavement remaining life of >20 years for all areas injected.

DCP Log

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