<p><p><figure id='attachment_2601' style='max-width:751px' class='caption aligncenter'><img class="wp-image-2601 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Diagram showing Deep Injection Procedure." width="751" height="435" /><figcaption class='caption-text'> Deep Injection Procedure (URETEK (2004))</figcaption></figure><h2>Basic Function</h2>Injected lightweight foam is used to compact and/or consolidate soft soil under foundations of construction projects.<br><h2>Advantages:</h2><ul> <li>Improves the subgrade or foundation condition</li> <li>Effective, cost effective, and quick</li> <li>Ten-year lifespan or more</li> <li>Minimal disruption to traffic</li> <li>Minimal noise</li> <li>Requires minimal equipment</li> <li>Environmentally safe materials</li></ul><h2>General Description:</h2>Lightweight foam fill is injected into the subgrade or foundation soil under foundations of construction projects. As the foam is injected, a combination of two chemicals creates a rapid expansion, which compacts the soil and provides consolidation.<br><h2>Geologic Applicability:</h2><ul> <li>The technology is suitable for low-density compressible soils.</li> <li>Groundwater is pushed aside as the polymer expands.</li> <li>Has improved support in peat type muskeg deposits.</li></ul><h2>Construction Methods:</h2>A series of small holes with a diameter of 0.63 to 0.75 in (16 to 19mm), are drilled at intervals of 4 to 8 feet (1.2 to 2.4 m) to depths of 30 ft (9.1 m) or greater. Primary injection for stabilization of the soil is done to depths between 3 and 9 ft (0.9 to 2.7 m). The secondary injection densifies the soil and is completed to a depth between 7 and 30 ft(2.1 to 9.1m). The holes are sleeved with a plastic or copper pipe and high-density polyurethane foam is injected. A chemical reaction occurs that causes the foam to expand, compacting the surrounding soil and inducing pressure that provides consolidation. The amount of compaction is dependent on the rate of injection at specific depth intervals and the location of the pipes and maintaining ground elevation. Method performs better when the temperature is cooler. Upper levels of the soil are generally densified first. A cement grout can be used after completion to seal the holes.<br><h2>Additional Information:</h2>The polyurethane foam to expand up to 30 times its original size. The density of the material as a range of 6.2 lb/ft3 (100 kg/m3 ) to 18.7 lb/ft3 (300 kg/m3). The polyurethane cures quickly so that sections can be competed in hours. All materials are environmentally safe. Filling large areas may not be economical.<br><h2>SHRP2 Applications:</h2><ul> <li>Embankment and roadway construction over unstable soils</li> <li>Roadway and embankment widening</li> <li>Stabilization of pavement working platforms</li></ul><h2>Example Successful Applications:</h2><ul> <li>Interchange of I-39/USH 78 – Wisconsin</li> <li>I-55/US 78 – Mississippi</li> <li>Deep Injection Process on a Building Structure - Kentucky</li></ul><h2>Alternate Technologies:</h2><ul> <li>Pavement patching, asphalt concrete overlay, and mudjacking.</li> <li>Potential Disadvantages:</li> <li>Can be costly to fill large voids.</li> <li>Polyurethane in pavement has insulating effect that can cause some differential frost heave.</li> <li>New cracks may be created and existing cracks may open again.</li> <li>Resettlement may occur after injection.</li></ul><h2>Key References for this Fact Sheet:</h2>Abu Al-eis, K. and LaBarca, I.K. (2007). Evaluation of the Uretek Method of Pavement Lifting. WI-02-07, Wisconsin Department of Transportation.<br>Crawley, A.B., Albritton, G.G., and Gatlin, G.R. (1996).</p><p>Evaluation of the Uretek Method Pavement Undersealing and Faulting Correction. Interim Report, FHWA/MS-DOTRD-96-113, Mississippi Department of Transportation Research Division.</p><p>URETEK (2004). The Uretek Deep Injection Process (UDI) for Roadways and Building Structures. URETEK USA, Tomball, TX.</p></p>