Assessing Pavement Modulus under Varying Temperatures: FWD Measurements on Edmonton’s Smart Road

Abstract: Accurately assessing pavement stiffness is critical for designing durable pavements and implementing effective maintenance strategies. This study examines the influence of temperature on pavement response using Falling Weight Deflectometer (FWD) measurements collected over the past five years on a smart road test section in Edmonton, Alberta. Measurements taken at 20°C and 35°C were used to back-calculate dynamic modulus (E*) master curves through Laplace and Henkel transformations. At 20°C, the E* curves exhibited typical linear viscoelastic (LVE) behavior, aligning with the expected stiffness characteristics of asphalt. However, at 35°C, a significant reduction in E* was observed, suggesting that the asphalt had likely transitioned into a non-linear viscoelastic state due to the elevated temperature.
The reduction in modulus at higher temperatures indicates that standardized FWD loading may induce excessive strains, pushing the material beyond its LVE range. Asphalt mixtures soften considerably at elevated temperatures, and applying the same load used in cooler conditions could lead to inaccurate stiffness measurements. This can result in overdesigning pavement sections and prompting premature maintenance interventions. To mitigate these issues, reducing the FWD load at higher temperatures is proposed, ensuring that applied stresses remain within the LVE range for more accurate modulus calculations. This approach would improve the reliability of pavement design and maintenance strategies, particularly in regions prone to high temperatures.