Climate-based performance zoning of asphalt binder for pavement design on the Kabul-Salang highway, Afghanistan

Abstract This study aims to develop a performance grade (PG) zoning map for asphalt pavements along the Kabul–Salang Highway in Afghanistan, considering local climatic conditions and traffic factors, to support optimized binder selection and enhance pavement durability under varying thermal and mechanical stresses. Daily temperature data spanning over 13–14 years from 25 meteorological stations were analyzed, and pavement temperatures were estimated using both SHRP and LTPP models, with the SHRP model selected for a more conservative minimum pavement temperature. Spatial interpolation was performed using the Inverse Distance Weighting (IDW) technique in ArcGIS to generate the PG performance zones, and traffic load and speed variations were also considered in adjusting the PG grades based on Asphalt Institute guidelines. Nine distinct PG binders were recommended along the highway, ranging from PG64-20 in warmer lowland zones to PG52-32 in colder high-altitude areas, ensuring 98% design reliability. The analysis shows that colder regions are highly susceptible to thermal cracking, while rutting is less critical in warmer sections, indicating that a single binder grade is insufficient for the entire corridor and highlighting the need for location-specific PG selection. The developed PG zoning map provides a practical framework for binder selection and pavement design along the Kabul–Salang Highway, offering actionable guidance to engineers, policymakers, and contractors to improve pavement performance, minimize cracking, and enhance the long-term durability of Afghanistan’s highway infrastructure.