On the thermal sensitivity of unbound granular pavement layers

Eyal Levenberg*, Irene Rocchi

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


The reversible mechanical behavior of unbound granular layers (UGLs) is commonly characterized by a stress-state dependent resilient modulus. This paper investigated the dependency of in situ resilient modulus upon a change in temperature above freezing conditions, i.e., the thermal sensitivity of UGLs in pavement systems excluding frost action. Such sensitivity is usually ignored in design and analysis because, on a material level, resilient modulus parameters are temperature independent. A model was developed to analyze this dependency by considering the stress-state changes that arise when UGLs are suppressed from thermally expanding or contracting. The formulation was incremental, based on linear thermoelasticity equations, and required as input readily available information; it assumed that changing temperature conditions are exogenous to the model and that no external loads are applied. A transcendental equation was subsequently derived, from which the sought sensitivity of UGLs could be resolved and quantified. Based on a parametric investigation of the model, covering a wide range of representative parameters, it is concluded that UGLs exhibit non-negligible thermal sensitivity. The extent of the calculated sensitivity coincides with field observations based on deflection testing, and also with seasonal factors that are traditionally applied to adjust field-measured moduli. Ultimately, the study shows that resilient modulus of UGLs is governed by an initial stress-state that is associated with a certain reference temperature level, and also by the temperature change compared to the reference.
Original languageEnglish
JournalInternational Journal of Pavement Research and Technology
Pages (from-to)32-39
Publication statusPublished - 2020

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