Evaluating the Short-term Performance of Spray-on Rejuvenators using a Modified Bending Beam Rheometer Test Methodology

Spray-on rejuvenation is a preventive maintenance strategy that highway agencies use to prolong the service life of asphalt pavements. This process involves applying rejuvenators on the surface of asphalt pavement to reverse the stiffening caused by aging. However, with several rejuvenators available on the market, it can be challenging to select specific products without understanding their effects at the mixture level. In this study, 12 different spray-on rejuvenators were applied on two different test sections (each with multiple test cells) at the Minnesota Road Research Facility. To assess the short-term (1-2 months) performance of rejuvenators, bending beam rheometer (BBR) test beams were prepared from the surface of the field-extracted cores, and a creep stiffness test was performed. The creep stiffness was measured at three different temperatures to evaluate the effectiveness of rejuvenators at these temperatures. The BBR test was not used to assess the low-temperature cracking resistance; instead, it was simply used to measure the beams' linear viscoelastic property (i.e., the creep stiffness). Results indicated that the effect of rejuvenation is more evident at higher temperatures (20 degrees C in this case). Besides, specific unexpected effects of rejuvenator products were observed. One of the test sections included extensive microcracks visible on the surface (presumably because of construction-related issues). Some of the rejuvenators closed these microcracks, leading to a "bridging" effect and increasing the stiffness of the BBR beams. This study provides a reference for evaluating the effect of spray-on treatments at the asphalt mixture level, which can assist roadway agencies in decision-making.