Method for determining the sensitivity to oxidation of a bituminous binder by electron spin resonance

A method for classifying a bituminous binder as a function of its ageing stability, in particular as a function of its susceptibility to oxidation, comprising:

• analysing a sample of the bituminous binder by means of electron spin resonance and measuring the integral of the signal of the carbon-centred stable radicals;
• accelerated ageing of the bituminous binder;
• analysing a sample of the aged bituminous binder obtained from step 2) by means of electron spin resonance and measuring the integral of the signal of the carbon-centred stable radicals;
• determining the percent increase in the number of carbon-centred stable radicals in the bituminous binder by comparing the integral of the signal of the carbon-centred stable radicals of the bituminous binder obtained in the analysing step and that obtained in the analysing the aged sample step;
• and
• determining the level of susceptibility of the bituminous binder:
• low in the case of an increase in the number of stable radicals of less than 60%;
• medium in the case of an increase in the number of stable radicals of 60-80%, or high in the case of an increase in the number of stable radicals of more than 80%.