Laboratory Investigation of Prewet Deicer Performance for Winter Mobility in the Pacific Northwest

Applying prewet deicers to roads during adverse winter weather is a cost-effective strategy to improve transportation safety and mobility. Prewet deicers have a small amount of liquid product applied to solid salt or salt/sand that speeds up ice melting and reduces deicer bounce-and-scatter loss. This study first presents the results of an in-depth survey of the Pacific Northwest on prewetting practices and then presents laboratory tests that quantified the ice melting, frictional behavior, and variation in snow–pavement bond strength of salt prewetted with various liquid deicers and at various rates. An ice melting test is a broadly accepted method to gauge the basic performance of deicers in a laboratory. More sophisticated laboratory tests on asphalt pavement samples with realistic snow and representative trafficking motion and forces were conducted. The laboratory tests confirmed that the prewetting liquid-to-solid application rate in the range of 33–67 L/t (8–16 gal./t) is reasonable for increasing the speed and total ice melting capacity (IMC) of solid salt. Furthermore, prewetting significantly reduced snow–pavement bond strength but did not increase friction more than dry salt.