UDI Demo Project for Caltrans District 12

Problem

In Orange County, California, Caltrans District 12 officials wanted to see for themselves what URETEK Deep Injection® (UDI) was all about. Caltrans requested a demonstration project and chose for the location an 80’ x 8’ area on SR 91 and 241 Tollway. The roadway was exhibiting signs of settlement and needed stabilization. The settlement problems visible at this test location were present in several areas all over this location. However, for this demonstration project, District 12 wanted URETEK to confine the work to one specific location.

Analysis

URETEK crews arrived on the scene to evaluate the problem and consult with Caltrans officials. The consensus view was that the area did not need any lift. Caltrans District 12 and URETEK agreed that the primary need at this location was for stabilization to stop the settlement.

Solution

On July 10, 2020 URETEK crews arrived on location and began developing an injection plan. Following Dynamic Cone Pene-trometer (DCP) testing, URETEK’s on-site supervisor approved a plan that involved stabilizing the area at three levels. The approach involved injections at 4’ and 8’ along two rows on either side of the problem area, combined with injections at 6’ down the center of the work zone, in what is referred to as a “5 on the dice” application. This approach was chosen to add more stability and structure to the base and subbase soils by locking up weak and poorly compacted soil at three levels, with the center row providing additional stabilization. During work at the project site, URETEK’s supervisor located a 2’ X 1’ hole just outside the test area and mentioned this situation to Cal-trans officials. He explained that this hole might be one of the contributing issues that led to settlement at the site and explained that if water should get into the opening, it could lead to major issues for Caltrans. District 12 approved the additional work scope and URETEK crews filled and locked up the identified void as well.

Result

For this demonstration project, URETEK was allotted 4,000 pounds of material and nine hours of time to complete the work. The project was completed using a little over 2,600 pounds of material in only five hours, with all work conducted overnight to minimize the impact on traffic. During the project, Caltrans officials remarked on URETEK’s use of a laser monitoring system and were impressed with the capability the equipment provided. URETEK successfully stabilized the 80’ x 8’ test area at three different levels while also addressing an additional void space identified just outside the test area. Upon completion of the work, the test area was stabilized and locked in place to avoid future settlement on the SR 91 and 241 Tollway connector. Caltrans was quite pleased with the work, and appreciated the additional effort and overall professionalism demonstrated by URETEK’s supervisor and crew.

URETEK Deep Injection® (UDI)

Widely referenced throughout our industry, UDI involves the injection of structural polymer into base and subgrade soils to increase the load bearing capacity. This is achieved by injecting the polymer through small holes drilled directly through the pavement structure to depths determined by site-specific analysis. Our URETEK 486 Star® material flows easily into voids and weak zones within the soil mass below. Through a controlled chemical reaction, the expanding polymer compacts surrounding soils and applies a controlled pressure on targeted areas of the affected pavement above. If needed, a multi-injection design plan is utilized to gently return the pavement to its original grade. The composite material quickly cures into a strong, dimensionally stable, and water-resistant geo-material, providing years of reliable service.

URETEK 486 Star®

URETEK 486 Star® polymer is a two-component, high-density, expanding thermoset polyurethane system. It was developed to be the ideal solution for under-sealing, void filling, lifting of settled pavement, stabilization and stiffening of weak soils, and for encapsulating and sealing buried infrastructure. URETEK 486 Star® is environmentally inert, non-toxic, and resists underground water erosion or weakening due to its industry-leading hydrophobic properties.