Towards the local expansion and contraction measurement of asphalt exposed to freeze-thaw cycles

- Local contraction of several asphalts under freeze-thaw cycle were measured.
- Description of the local response of the asphalt under freeze-thaw cycles was provided.
- Thermal strain fields are heterogeneous and mainly sustained by the mastic.
- The interaction between mastic and aggregates was experimentally characterized.
- The apparent coefficient of thermal contraction of the mastic was measured.

This paper aims at analyzing the local strain fields in several asphalt mixtures exposed freeze-thaw cycles. Four types of asphalt with different Recycled Asphalt Pavement (RAP) content (0%, 20%, 40%, and 100% of RAP) were considered. They were subjected to freeze-thaw cycles, in the temperature range of −11 °C and 20 °C. The local contraction/expansion of these samples during the cooling/heating was measured using the Grid Method (GM) and Digital Image Correlation (DIC). The strain distribution is very heterogeneous due to the difference between the thermal contraction coefficients of aggregates and mastic (i.e., bitumen and filler). The thermal responses of the mixture under study were compared at the micro- and the macro-scales.

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