Concrete Pavement – Dips & Faulted Longitudinal & Transverse Joints

Problem:

Concrete pavement settlement, whether settlement of several panels across all lanes to form a dip or one lane with settled panel(s) causing a faulted longitudinal joint or multiple panels in succession with faulted transverse joints, is most often caused by weak foundation soils insufficient to support the heavy tractor trailer loads or the increased truck traffic counts. Once the pavement begins to settle, the pavement system typically is more susceptible to water intrusion, exacerbating the situation.

Solution:

Roadway surfaces that have settled can be stabilized and lifted by injecting polymer through tubes at multiple elevations, strengthening the weak sub-grade soils. This is accomplished by taking DCP tests before the injection process to determine the elevation(s) where the injections will be done; then drilling multiple 3/4″ holes through the concrete and injecting polymer through tubes placed at the level(s) of the weak area(s) into the foundation soils. This is usually done on a 4′ grid pattern in 4′ elevations. URETEK monitors the surface using laser monitors and/or dial indicators and knows that the roadway has become adequately supported when an indication of movement is detected on the monitors. Injection is continued into the soils to lift the pavement to grade – returning the pavement to original construction, concrete on base on stiffened sub-base/subgrade. If the faulted joint experiences aggregate lock prior to completing the lift, the joint may require full depth saw cut or if minor can be touched up with diamond grinding.

Expected Results:

  • Foundation soils will be sufficiently stiffened to support the load and mitigate future settlement.
  • Deflections will be reduced and Load Transfer Efficiencies improved.

Benefits:

  • Zero daytime lane closures.
  • Pavement life extended with proper support of the pavement.
  • Safety hazard eliminated.
  • Injection can be accomplished in wet soil conditions as the URETEK 486 STAR hydro-insensitive polymer will form a dimensionally stabile polymer even when injecting into saturated soils. The expansion process will also drive the water out of the soil system.

Alternates:

  • Utilization of concrete slurry directly under slab has many weaknesses:
    • Difficult to control the lift.
    • Material setup time is long and material can travel far beyond the point of installation – often times requiring significant additional material and/or causing environmental concern.
    • Vibration from traffic in adjacent lanes can cause water separation and thus a poor end product.
    • Does not have the tensile strength to hold up under the vibration of traffic
    • If a blow-out occurs– there is a significant delay while the material hardens before injection can continue.
    • While cement slurry is often used to fill large voids, it is ineffective where there are small pockets of void or weak soils as it is difficult to identify exactly where those voids or weak soils are and should be injected.
  • Polyurethane injection directly beneath the concrete to fill voids and lift has many weaknesses:
    • Foundation soils that cause the settlement are not repaired.
    • While the polyurethane material by itself performs well on the Repeated Load, Permanent Deformation Testing, it does not have sufficient Resilient Modulus strength. The composite of the material injected into an aggregate, combines both Resilient Modulus strength with great resistance to permanent deformation.

Reference Documents:

  1. TXDOT Beaumont Project Report – Contains pre-injection and post-injection Falling Weight Deflectometer (FWD) test results and analysis performed by TXDOT on a jointed concrete pavement system. This report demonstrates the benefits of our process with significant decrease in deflections and significant increase in LTE at the joints. View Report.
  2. PennDOT Pilot Project Report I-80 (2012) – Contains pre-injection and post-injection Falling Weight Deflectometer (FWD) test results and analysis performed by PennDOT on a jointed concrete pavement system. This report demonstrates the benefits of our process with significant decrease in deflections and significant increase in LTE at the joints. View Report.
  3. Executive Report Rev 1 (Boudreau) – Summarizes the results of material testing research performed by Rick Bourdreau doing Resilient Modulus and Repeated Load Permanent Deformation Testing. The testing looked at samples of various aggregates and our polyurethane by themselves and then the same aggregates after injection with polyurethane. View Report.