Method for accelerated aging of neat asphalt binder using microwave radiation process
AssigneeKansas Department of Transportation
InventorSafwat W. Bishara
Life of this patent
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Abstract
An improved method for simulating an oxidative aging of an asphalt sample comprises accumulating a number of samples from the asphalt load under test. The samples are initially heated by convection and microwave units to a common temperature. Subsequently, the samples are incrementally, as heated in a “ramp” control heating, from 27° C. to 147° C. over a 60-minute period. Subsequently, the samples are microwave heated for three successive 60-minute periods and one 30-minute period under a pressure of 440 psi. Upon pressure release, a subsequent short convection heating and subsequent degassing, a resulting aged residue is presented which is equivalent to residue provided by known conventional tests but at a reduced time period.
Claims14
A method for producing an asphalt sample simulating an oxidative aging of the asphalt comprising the steps of:
- (a) accumulating a sample of the asphalt from the asphalt mass to be tested;
- (b) providing a calibrated microwave unit;
- (c) placing the asphalt sample within the microwave unit;
- (d) pressurizing the sample at a selected pressure of about 440 psi;
- (e) monitoring the temperature of said sample;
- (f) initially operating the unit for providing microwave radiation about the sample for heating the sample to a first selected temperature of approximately 27° C.;
- (g) operating the unit for providing microwave radiation about the sample at a power incrementally increasing the sample temperature from said first temperature to a desired second temperature of approximately 147° C. over approximately a first 60-minute period;
- (h) upon said sample reaching said second temperature operating said microwave at said second temperature for maintaining said sample at said second sample temperature for approximately a period of time of 210 minutes;
- (i) releasing the pressure from said asphalt sample for returning said pressure on said sample to an ambient air pressure;
- (j) placing said sample in a convection oven and heating said sample at approximately a 150° C. temperature for approximately five minutes;
- (k) degassing said sample whereby to present an asphalt sample simulating an accelerated oxidative aging for subsequent analysis of selected parameters of said asphalt.
A method providing an asphalt sample simulating an oxidative aging including the steps of:
- (a) providing at least one sample of asphalt from an asphalt mass to be tested;
- (b) heating said at least one sample in a convection oven to a preselected temperature;
- (c) placing said at least one sample within a calibrated microwave unit;
- (d) placing said at least one sample under a selected pressure of about 440 psi;
- (e) initially operating the unit to heat the sample by microwave radiation to a first selected temperature of approximately 27° C.;
- (f) operating said microwave unit for incrementally increasing the sample temperature from said first temperature to a desired second temperature of 147° C. over a first 60-minute period of time;
- (g) operating said microwave unit for a second preselected period of time of approximately 210 minutes at said second temperature of 147° C. for continuously heating said at least one sample at a constant temperature;
- (h) releasing the pressure from said at least one asphalt sample;
- and
- (i) degassing said at least one sample whereby to present said at least one asphalt sample characteristic of having undergone an accelerated aging.
A method for providing an asphalt sample simulating an oxidative aging including the steps of:
- (a) providing a plurality of discrete samples of asphalt from a single asphalt mass;
- (b) initially heating said samples in a convection oven for bringing said samples to a first common starting temperature;
- (c) operating the microwave to heat said samples to a second common starting temperature;
- (d) pressuring said samples to a preselected pressure adapted to simulate an aging of said samples as if in use for a preselected extended period of time upon a subsequent microwave heating of said samples;
- (e) subsequently operating the unit at a first selected microwave power of microwave radiation for incrementally increasing the samples temperature from said second common starting temperature to a higher preselected temperature over a first selected time period;
- (f) subsequently operating said unit of said preselected higher temperature at said second temperature at a second selected microwave power, said preselected microwave powers, temperatures and time periods chosen to simulate an oxidative aging of said samples representative of preselected aging period of time;
- (g) releasing the pressure from said asphalt samples;
- (h) heating said samples in a convection oven;
- (i) degassing said samples whereby to present asphalt samples simulating said aging period of time.
Dependencies are inferred from the claim text.