Full-Scale Field Testing for Verification of Mechanical Properties of Polyurethane Foams for Use as Backfill in PCC Repairs

Laboratory and field investigations were performed on several commercially available rigid polyurethane foam materials to determine their suitability as base replacement materials for full-depth portland concrete cement (PCC) pavement repairs. Rigid polyurethane foam (RPF) specimens were prepared and tested to evaluate the compressive strength, reactivity, and density of several foam materials under a variety of temperature conditions, where properties were investigated for thermal variations expected in field placement. Following laboratory testing, full-scale field testing of full-depth PCC repairs was conducted using two RPFs of densities of approximately $160\text{kg}/{\text{m}}^3$ $\left(10\text{lb}/{\text{ft}}^3\right)$ and $240\text{kg}/{\text{m}}^3$ $\left(15\text{lb}/{\text{ft}}^3\right)$ to verify laboratory predicted performance under elevated and ideal field temperatures. Each repair was trafficked within 3 h of repair completion with an F-15E load cart to simulate fighter aircraft traffic on early-age repairs. Results of laboratory and field testing indicate that high-density RPF materials are suitable as base replacement materials for temporary pavement repairs on airfields. For optimum field performance a RPF with minimum density of $240\text{kg}/{\text{m}}^3$ $\left(15\text{lb}/{\text{ft}}^3\right)$ should be placed at a temperature of $23°\text{C}$ $\left(70°\text{F}\right)$ .