Differential thermal expansion and contraction: a mechanistic approach to adhesion in asphalt concrete

This paper introduces a simple mechanistic approach that describes the response of the asphalt-aggregate system to temperature changes. The concept recognizes the thermal incompatibility between asphalt cement and aggregate. Owing to the considerable difference in the coefficients of thermal expansion of aggregate and asphalt, the asphalt matrix will attempt to contract more than the aggregate during thermal cooling. An analytical model was derived to estimate the thermally induced stresses resulting from differential thermal contraction. The experimental investigation which is part of a study investigating adhesion, verified the findings of the analytical approach. Findings from this study explained field and laboratory observations made earlier by other investigators. These observations were associated with asphalt concrete low-temperature performance and its resistance to stripping.Cet article pr\ue9sente une approche m\ue9canistique simple qui d\ue9crit la r\ue9ponse de syst\ue8mes asphalte-agr\ue9gat aux changements de temp\ue9rature. Le concept tient compte de l'incompatibilit\ue9 thermique entre le ciment asphaltique et l'agr\ue9gat. \uc9tant donne Ia diff\ue9rence consid\ue9rable dans les coefficients de dilatation thermique de l'agr\ue9gat et de l'asphalte, la matrice d'asphalte aura tendance a se contracter davantage que l'agr\ue9gat durant le refroidissement thermique. Un mod\ue8le analytique a \ue9t\ue9 d\ue9veloppe afin d'\ue9valuer les contraintes thermiques qui r\ue9sultent de Ia contraction thermique diffl:rentie1le. Cette analyse exp\ue9rimentale, qui fait partie d'une \ue9tude de l'adh\ue9rence, avait pour but de v\ue9rifier les r\ue9sultats de Ia m\ue9thode analytique. Les r\ue9sultants de cette \ue9tude ont corrobore les observations faites pr\ue9c\ue9demment en laboratoire et sur le terrain par d'autres chercheurs. Celles-ci concernaient la performance du b\ue9ton asphaltique \ue0 faible temp\ue9ratures et sa r\ue9sistance \ue0 Ia d\ue9solidarisation.Peer reviewed: YesNRC publication: Ye