METHOD FOR DETERMINING THE SENSITIVITY TO OXIDATION OF A BITUMINOUS BINDER BY ELECTRON SPIN RESONANCE
This invention concerns a method for analysing the ageing stability of a bituminous binder, in particular by reference to its susceptibility to oxidation, by 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, comprising: i) heating the bituminous binder, followed by ii) heating the bituminous binder resulting from step i) under pressure; analysing a sample of the aged bituminous binder obtained from step b) by means of electron spin resonance and measuring the integral of the signal of the carbon-centred stable radicals; and comparing the integral of the signal of the carbon-centred stable radicals of the bituminous binder obtained from the first step and that obtained from the previous step.
1 . A method for analysing the ageing stability of a bituminous binder, in particular by reference to 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, comprising:
i) heating the bituminous binder, followed by
ii) heating the bituminous binder resulting from step i) under pressure;
analysing a sample of the aged bituminous binder obtained from the accelerated ageing step by means of electron spin resonance and measuring the integral of the signal of the carbon-centred stable radicals; and
comparing the integral of the signal of the carbon-centred stable radicals of the bituminous binder obtained from the analysing step and that obtained from the analyzing the aged sample step.
2 . The method according to claim 1 , wherein step i) of accelerated ageing of the bituminous binder takes place between 100 and 200° C. for a duration of between 5 and 200 min.
3 . The method according to claim 1 , wherein step ii) of accelerated ageing of the bituminous binder occurs between 50 and 150° C., at a pressure ranging from 0.5-5 MPa, over a duration of between 1 and 100 h.
4 . The method according to claim 1 , wherein step i) of accelerated ageing of the bituminous binder corresponds to a Rolling Thin Film Over Test.
5 . The method according to claim 1 , wherein step ii) of accelerated ageing of the bituminous binder corresponds to a long-term accelerated ageing test in a pressure ageing vessel.
6 . 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%.
7 . The method according to claim 6 , wherein the accelerated ageing of the bituminous binder comprises: i) heating the bituminous binder, followed by ii) heating the bituminous binder resulting from step i) under pressure.
8 . The method according to claim 6 , wherein the level of susceptibility of the bituminous binder is:
extremely low in the case of an increase in the number of stable radicals of less than 40%;
very low in the case of an increase in the number of stable radicals of 40-50%,
low in the case of an increase in the number of stable radicals of 50-60%,
medium in the case of an increase in the number of stable radicals of 60-70%,
medium-high in the case of an increase in the number of stable radicals of 70-80%,
high in the case of an increase in the number of stable radicals in the number of stable radicals of 80-90%, or
very high in the case of an increase in the number of stable radicals of more than 90%.
9 . A method for continuous monitoring of the production of a bituminous binder, wherein the method is used on a production line in a refinery, wherein the continuously produced bituminous binder is regularly analysed according to the classification method according to claim 6 .
10 . A method for quality control of a bituminous binder, wherein the bituminous binder is analysed at the end of the production process by the classification method according to claim 6 .
11 . The method according to claim 7 , wherein step i) of accelerated ageing of the bituminous binder takes place between 100 and 200° C. for a duration of between 5 and 200 min.
12 . The method according to claim 7 , wherein step ii) of accelerated ageing of the bituminous binder occurs between 50 and 150° C., at a pressure ranging from 0.5-5 MPa, over a duration of between 1 and 100 h.
13 . The method according to claim 7 , wherein step i) of accelerated ageing of the bituminous binder corresponds to a Rolling Thin Film Over Test.
14 . The method according to claim 7 , wherein step ii) of accelerated ageing of the bituminous binder corresponds to a long-term accelerated ageing test in a pressure ageing vessel.