Full-Scale Field Testing for Injected Foam Stabilization of Portland Cement Concrete Repairs

A series of foam-injected repairs was performed on a portland cement concrete (PCC) test section at the U.S. Army Engineer Research and Development Center. Repairs consisted of uncompacted backfill overlaid by a 9-in, rapid-setting cementitious cap. A series of injection tubes was inserted through the cap into the uncompacted debris backfill, and a two-component rigid polyurethane foam was injected into this backfill. The test matrix compared the performance of three different repairs using various volumes of injected foam. A fourth repair was constructed without injected foam as a control item. Three hours after cap construction, the repairs underwent simulated aircraft traffic with an F-15E load cart. The performance of the four repairs was measured by passes to failure. The results of traffic testing were used to evaluate foam-injection technology for rapid repair of PCC pavements. The performances of foam-injected repairs were also compared with poured foam and traditional full-depth backfill repairs, each capped with rapid-setting materials. Comparisons were made about pavement performance, costs, and total duration required for installing the repair. Results showed that injection of excessive foam was detrimental to the repair surface, because it induced cracking before traffic application, and could lead to premature development of foreign object damage. However, repairs using moderate amounts of foam and pure backfill sustained the required traffic levels, defined by the research sponsor, of 200 passes within 4 h of initiating the pavement repair. For cost and repair duration, those repairs that did not include foam were more effective.