Improving the Foundation Layers for Pavements: Jointed Concrete Pavement Rehabilitation with Injected High Density Polyurethane Foam and Dowel Bar Retrofitting – Pennsylvania US 422 Field Study - TPF-5(183)

(2015) Improving the Foundation Layers for Pavements: Jointed Concrete Pavement Rehabilitation with Injected High Density Polyurethane Foam and Dowel Bar Retrofitting – Pennsylvania US 422 Field Study - TPF-5(183).

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Abstract

This report is one of the field project reports developed as part of the TPF-5(183) and FHWA DTFH 61-06-H-00011:WO18 studies. This report presents experimental test results and analysis from a field evaluation conducted on a 15-year-old jointed portland cement concrete pavement section on US 422 near Indiana, Pennsylvania. The pavement exhibited premature mid panel cracking and faulting. A 9.7 km section of the highway was rehabilitated by injecting light weight high density polyurethane foam into the underlying opengraded stone (OGS) layer to improve support conditions beneath the pavement and installing dowel bar retrofits at selected crack locations to improve load transfer efficiency. A 160 m long section of the project was stabilized with cementitious grout for comparison with areas that were stabilized with HDP foam. Laboratory testing was conducted on OGS and OGS+foam mixture samples to determine undrained shear strength and resilient modulus properties. Field testing was conducted in several test sections before and after HDP/cementitious grout stabilization, after dowel bar retrofitting, and six to nine months after stabilization for performance evaluation. Testing that was conducted in full-depth patching areas after HDP foam injection provided the opportunity to observe migration of the injected foam and directly test the stabilized support layers under the pavement. Field observations indicated that the foam did not fully penetrate the full width and depth of the OGS layer, thus creating non-uniform support conditions with variable stiffness, strength, and permeability characteristics. OGS+foam material showed lower permeability, lower elastic modulus, and high shear strength, than OGS material alone, in both lab and field testing. Pavement surface elevation monitoring results indicated that the slab movements were greater than the allowable 1.3 mm per specifications, and better process control measures are needed to control vertical movements, particularly with the HDP stabilization method. FWD test measurements showed improvements near cracks and joints in both cementitious and grout stabilized sections, although no statistically significant improvements were observed near mid-panel. The findings of this study improve the understanding of the benefits and limitations of using injected foam technology to rehabilitate concrete pavements.