Tuesday, November 28, 2017

Functional Differences Between Asphalt Rejuvenator Emulsions & Asphalt Seal Coat Emulsions in Protecting Pavement Surfaces


Asphalt rejuvenators & seal coat formulations have emerged regionally over the last 20+ years as pavement maintenance applications to combat environmental factors causing deterioration of asphalt pavements. Use of rejuvenators is more common in western regions of the US while asphalt seal coat is more often used in regions of the Midwest, Northeast and South. Both technologies evolved by design to arrest the identifiable mechanisms of pavement distress leading to pavement failure. But the major environmental causes of surface weathering in Denver may not be the same as those in Boston.

In hot dry climates of the West, the primary cause of pavement deterioration is oxidation and embrittlement of asphalt binder at the pavement surface from prolonged exposure to sun & high temperatures. Loss of fine aggregates from the surface of the asphalt pavement matrix is often attributed as the main cause leading to raveling of larger aggregate and ultimate pavement failure. Rejuvenators are generally asphalt emulsions containing lighter asphalt fractions to re‐soften oxidized asphalt binder at the pavement surface, which assists the binder in retaining encapsulated aggregate fines, and minimizing aggregate loss by traffic wear. In northern regions of the country, asphalt binder oxidation is a minor contributing factor of pavement wear. The major destructive factors of pavements in these regions are water penetration and stresses induced by repeated freeze/thaw cycles, leading to pavement cracking, further water intrusion and subsequent erosion of the pavement sub‐base. Seal coat mix formulations are designed to provide a sealing membrane to protect the pavement surface from water penetration, and better address the environmental factors to preserve pavement surfaces encountered in the Midwest and Northeast. Seal coat formulations usually containing sand are widely used in parking lot maintenance programs and are found to be effective in prolonging pavement assets in these areas, where use of rejuvenator formulations is comparatively rare. Both asphalt based rejuvenators and pavement seal coat formulations can be effective, but were each designed to address different climatic factors unique to regional climates, and not suited to one‐size‐fits‐all remedies.

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