Field Testing PlusTi™ Road Penetrants for Urban Heat Island Mitigation in Under-Resourced Neighborhoods

Charleston County, South Carolina, USA partnered with Pavement Technology, Inc in 2021 and again in 2023 to deploy a pavement rejuvenator containing titanium dioxide on selected urban roadways. The product does not alter the color of the surfaces, but laboratory tests suggest the treatment triples the solar reflectance index of pavements, primarily caused by its photocatalytic properties. During the summer of 2023 members of the Charleston Heat Health Research Project were invited to field test the effectiveness of the 2021 asphalt treatment (Union Heights neighborhood) and recent 2023 application on an asphalt road and concrete sidewalk (Eastside neighborhood). These neighborhoods are under-resourced and were identified as heat islands by the 2021 Charleston HeatWatch mapping experiment. Wet bulb globe temperatures (WBGT) were calculated over treated and nearby untreated (control) surfaces at heights of 0.5 m and 2.0 m. The instruments were placed over the road for the Union Heights case and over the sidewalk in the Eastside case. Furthermore, the Eastside case afforded a pre-treatment observation as well. WBGT measurements were taken every 5 seconds for 1-hour periods in the early morning, mid-day, afternoon, and post-sunset. Forward Looking Infrared (FLIR) temperature measurements of surrounding surfaces were also taken at 10-minute intervals. As expected, the 0.5 m WBGT was consistently higher than the adjacent 2.0 m WBGT. Much of the mid-day and afternoon periods exceeded heat safety standards (i.e., typical “black flag” conditions > 32.2° C [90° F]). The presentation will focus on WBGT and FLIR comparisons to assess the usefulness of PlusTi™ for enhancing heat resilience.