BINDER-MIX RHEOLOGY: LIMITS OF LINEAR DOMAIN, NON LINEAR BEHAVIOUR

Correlations between binder and mix rheology are fundamental to understand the effect of a binder on the mix behaviour, mix being the final product laid on the road. For this binder-mix analyses, it is necessary to distinguish two behaviour domains : the linear domain (where the binders are classically tested) and the non-linear domain (where irreversible formations appear). A study of binder-mix behaviour needs to be done in the same domain in order to be valid. The analysis, in the linear domain, for pure bitumen (with different grades) used with different mix designs is presented. The important result is the very good correlation between shift-factors for the binder (after RTFOT) and the mix (correlation factor = 0.99). These shift-factors have been determined with measurements of Complex Modulus on the binders and on the mixes, both materials being tested in the linear domain. This correlation is valid only for this behaviour domain. Another correlation between binder and mix moduli is also presented. The non-linear domain, where irreversible deformations take place, is more complicated. If this domain is already studied for mixes (through fatigue and creep tests), no analyses are made for the binders in this domain. Results obtained up to now for the binders can only be considered as initial conditions of the non-linear behaviour of the binder. (A) For the covering abstract see IRRD 885061.