Our nation’s roadways are critical to our economic strength and to our way of life. Every one of us knows the pleasure of driving down a newly-finished stretch of road. Unfortunately, we also understand how many of the roads we travel have suffered from settlement issues over the years.
URETEK Deep Injection (UDI) is the rapid, economical solution for repair and maintenance of the roads that connect us and keep our nation moving.
For pavement preservation, UDI offers almost immediate results, returning roads and highways to a safe and level condition above stabilized soils in much less time and for dramatically less money than full-reconstruction methods.
Common Causes of Road Settlement Issues
Both natural and man-made causes can lead to weak soils beneath pavement systems. The original soil composition may have included loosely-packed materials that were not packed well before construction, or nearby drilling or excavation may have resulted in compromised soil quality. Regardless of the cause, weak soils generally result in subsidence, which often leads to the formation of voids beneath the surface in base and subbase soils. Left unchecked, subsidence can have a negative impact on pavement systems. Symptoms of weak soils include foundation settlement, cracks in slabs, dips and heaves, a rough ride for drivers, and evidence of soil subsidence in proximity to the roadway.
For roads and highways, common problems include broken or separated concrete slabs, faulted joints, subsurface voids, and sloping or inconsistent pavement levels that also result in poor driving conditions and lead to expensive vehicle maintenance issues for drivers.
Traditional Repair Methods
Over the years, Federal and State DOTs, Departments of Public Works, Airport authorities, and other transportation asset managers have applied an assortment of solutions to address the repair and maintenance of their deficient paved assets. Some of these traditional solutions include:
- Asphalt Overlay – Just as asphalt is used as a primary material for roadways, because of its reduced cost and greater flexibility, it is also frequently used to repair deficiencies such as uneven surfaces, misaligned panels and pavement settlement. To address these problems, a hot mix of asphalt (HMA) is spread over an existing surface to fill in and cover up the deficient area. The thickness of the asphalt overlay can vary anywhere from ½” to several inches depending on the magnitude of the problem. The success of this technique depends to a great extent on the condition of the base soil beneath the roadway. If the base is weak, unstable, or if it contains multiple void spaces, the repaired surface is likely to experience a repetition of the failure.
- Cementitious Grouting – This process typically involves the use of a water/soil/fly ash/cement mixture injected by hydraulic pressure under pavements to void fill and support the damaged or settled areas. Unfortunately, the cementitious material is slow to cure (causing extended lane closures); as it cures it shrinks (taking any lifted panels out of level); and once cured lacks sufficient tensile strength for long term effectiveness. When used to fill subsurface voids, significant amounts of the material must be pumped in to ensure the underground space is completely filled. Once the cementitious material hardens, its inherent weight of 140 lbs/ft3 adds excessive weight burden to an already distressed base soil condition. When used to repair bridge approach slabs, the added weight issue of cementitious grout can also complicate adjacent utility conduits and piping located beneath the surface of the structure. If enough force is applied, the pressurized grout can move existing utilities out of alignment or force its way into cracks that exist within underground pipes or lines.
- Full Depth Pavement Removal and Replacement – The typical full depth replacement process can take weeks or months to fully complete and rehabilitate. During this period, traffic must be re-routed around the repair area, contributing to greater delays and disruption, to say nothing of the higher cost of such projects. Since 1989, URETEK has provided viable solutions to roadway and airport pavement repair and maintenance problems.
Locating the Problem Area
URETEK routinely begins each new highway pavement preservation job with on-site Dynamic Cone Penetrometer (DCP) testing, which is used to measure the comparative strength of the base soil layers beneath roads, airport pavements, and bridge approach/departure slabs. This information is used to determine exact locations and levels for the injection of the polymer material used to strengthen and densify problem soil strata.
Repairing the Problem Area
Once the problem areas have been identified, URETEK crews develop a site-specific injection plan to address the issues. Surface profiles are made to properly identify any differential settlement of the pavement, and then URETEK 486 Star® polymer is precisely injected via small (5/8″) diameter holes drilled through the pavement into the weak soils and identified void spaces below. Once injected, the polymer begins to expand and forms a stable, strong, lightweight replacement base material.
Because URETEK 486 Star® is hydro-insensitive, any trapped subsurface water or wet soil has no detrimental effect on the material’s structural integrity or performance, and in fact is repelled during the injection process. As the water is forced away, the wet soil is densified to provide a firm geo-material that lasts for years and years.
The injection process is repeated, using a gridwork of hole locations until the entire area is sufficiently filled and sealed by the polymer. If the road, runway, or panel also needs to be leveled or raised, this is achieved through further monitored injections.
Monitoring the Repair Process
As the pavement is lifted, its movement is precisely monitored on the surface using laser level measuring devices. The polymer expansion reaches 90 percent of its full compressive and tensile strength within approximately 15 minutes. Because the polymer material is extremely light, any additional overburden weight is kept to a minimum. The properties of URETEK’s polymer material is carefully matched to typical base material compressive strength characteristics.
URETEK Deep Injection® (UDI) is Ideal for the Following Roadway Applications
UDI involves the injection of structural polymer into base and subgrade soils to increase their 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. URETEK’s proprietary high-density polyurethane foam (HDPF) polymer material flows easily into voids and weak zones within the soil mass below. Then, through a controlled chemical reaction, the expanding polymer compacts surrounding soils, increasing their load bearing capacity. The composite material quickly cures into a strong, dimensionally stable, environmentally inert, non-toxic, and water-resistant geo-material that provides years of reliable service.
There are four key applications where UDI provides a significant advantage over more traditional methods in solving complex pavement lifting and soil densification problems:
- Void Filling – When weather conditions produce rain, snow, or severe temperature shifts, expanses such as fissures and water pockets can be created. Over time, these expanses form voids just below the pavement surface. These voids can result in settlement, potholes, sink holes or cracking that, in turn, can destabilize pavements. UDI is very effective in addressing these types of voids. URETEK’s expansive, hydro-insensitive polymer material drives out any standing water and aggressively fills voids. It also densifies the soil and prevents the expansion and formation of new voids in the future.
- Stabilization – By undersealing and void filling, UDI stabilizes roadways and prevents pumping or further differential settlement of these assets. UDI effectively fills, compacts, and stabilizes base soils beneath pavements and seals the area from any further water intrusion that could contribute to degradation. It is the only process that combines the benefits of sealing, stabilizing, and asset protection with rapid curing time; this allows the project area to be quickly repaired and returned to service.
- Lifting – UDI is quickly and economically applied to solving the densification, lifting, and realignment of both concrete and asphalt roadways. The expansive, hydro-insensitive properties of URETEK 486 Star® polymer ensure that settlement problems are properly corrected. Since the material is injected in layers, the amount of lifting can be controlled to within one tenth of an inch, which assures accurate lifting profiles.
- Sealing – Sealing joints and cracks from water leakage and seepage is one of the most important and frequently recurring problems facing many roadway surfaces. If left unattended, leaking joints and cracks can grow, further damaging the pavement and compounding void and settlement problems. To underseal pavements in these environments, URETEK’s industry-leading polymer material is strategically injected in a uniform grid pattern just below the surface. As the material is injected, it begins to expand, seeking out and filling sub-surface cracks, leaks, voids, and joints, providing a strong, stable and long-lasting seal that resists further water intrusion.
The UDI Advantage
- Fast – UDI requires no excavation, and projects can often be completed in hours or days. Traditional repair methods often involve excavation, and the time required for project completion can be weeks.
- Effective – URETEK’s 486 Star® polymer material has been used to successfully complete over 100,000 projects nationwide. The lightweight, expansive geo-polymer material not only realigns concrete pavement but also addresses the problem at the source – weak soil composition – giving customers a long-lasting solution.
- Economical – The repair process is priced consistently below alternative repair methods, and implementing repairs now significantly reduces further repair costs down the road.
- Minimally Disruptive – Unlike other repair methods, UDI is minimally disruptive and requires no excavation.
- Durable – URETEK’s 486 Star® polymer is specially formulated for stability and strength, even in the harshest environments. Our polymer is hydro-insensitive, and UDI is warranted against loss of dimensional stability or deterioration.
- Safe – Liability risk is greatly reduced with UDI due to an inherently safer working environment without deep excavation or heavy equipment. The process and material are eco-friendly and meet today’s high environmental standards.
Local DOT’s Rely on UDI to Keep Traffic Moving
Beginning in 1989, with the introduction of UDI, our trusted pavement preservation method has been relied upon by state DOT officials across the country. In every climate, they depend on UDI to stabilize soils, fill voids, and most importantly, maintain smooth and level roadways for our nation’s drivers.
Trusted Vendor for Highway Maintenance Programs
Since 1988, URETEK has been a trusted, reliable partner for DOT officials and Prime Contractors intent on maintaining critical pavement systems. With increasing traffic loads across the country, the need for reliability and trust has never been more important than it is today. With its rapid response and crew scheduling that takes advantage of overnight and off-peak hours, URETEK is the vendor most prepared to complete highway maintenance tasks without severely impacting traffic.
When we arrive, our crews get right to work on a site-specific repair or maintenance solution that quickly mitigates weak soil issues and extends the reliable working life of important pavement assets. Best of all, our zero-excavation solution means the work is completed in days, not weeks or months.
When the job involves stabilizing base and subbase soils and restoring critical pavement systems to their optimal functional state, nobody does it better, or faster, than URETEK.
Contact URETEK today to learn more about our speedy pavement maintenance and repair solutions that keep budgets in line while assuring many more years of reliable service from important roadways.