Composite Pavement – Stabilization at Joints & Cracks

Problem:

For composite pavement, the lack of a stable base and foundation soils beneath existing joints and cracks in concrete pavement is one of the causes of premature failure of the asphaltic concrete overlay. The unstable soils beneath the concrete cause the pavement to deflect as traffic loads are inefficiently transferred from one slab to another beneath the asphalt overly. In short order, the constant movement causes reflective cracking of the asphaltic concrete overlay. This reflective cracking then leads to water infiltration at the joints and cracks and even weaker pavement support. The continual movement of the pavement causes spalling of the asphalt overlay and significantly reduces the life of the overlay.

Solution:

Prior to the overlay, apply the URETEK Deep Injection Process with URETEK 486 water resistant expansive polymer to one row of injections on the approach and leave side of each joint and crack. Inject through tubes, to a depth of approximately 3′ into the foundation soils by drilling 3/4″ holes through the concrete and injecting through tubes into the soils. This is typically accomplished on a 4′ grid pattern. 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.

Expected Results:

  • Decreased deflections at the joints and cracks.
  • Increased Load Transfer Efficiencies (LTE’s) at the joints and cracks.
  • Extends the life of the overlay.

Benefits:

  • Zero daytime lane closures.
  • Multi-lane mile projects are accomplished with up to four production trucks and stay ahead of the prime contractor performing the mill/overlay.
  • 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:

  • Injecting a polymer directly under a composite pavement to stabilize the joints/cracks will likely cause delamination of the asphalt and concrete as material travels up through the joints and cracks to get into the interface between the concrete and asphalt. This causes removal of the entire asphalt layer, increasing the time to complete and the cost of the project. Additionally this alternate does not address the problem of weak supporting soils and will likely result in premature failure of the asphalt overlay if the foundation soils allow deflection of the pavement.
  • Removal and replacement of the entire pavement system (pavement and the weak foundation soils) is extremely expensive and results in significant traffic delays.

Reference Documents:

  1. VDOT I-81 Projects – Several projects have been completed on I-81 since 2009. Photos include reflective cracking prior to the project, URETEK injecting at night in 2009, photo from 2014 (five years later) showing no reflective cracking. View Photos.
  2. TXDOT Beaumont Project Report – contains pre-injection and post-injection Falling Weight Deflectometer (FWD) test results and analysis performed by TXDOT on jointed concrete pavement. This report demonstrates the benefits of our process with significant decrease in deflections and significant increase in LTE at the joints. View Report.
  3. 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.