Methods for testing and assessing asphalt concrete mixture workability and compactability

A method for predicting a temperature at which a certain material characteristic occurs for an asphalt concrete mixture, the method comprising the steps of:

• heating the asphalt concrete mixture to a first temperature;
• placing an asphalt concrete mixture in a molding apparatus, the molding apparatus having a moveable end plate;
• applying a force to the asphalt concrete mixture in the molding apparatus at a predetermined rate and through a first stress level and a second stress level;
• measuring the applied force and one or more heights of the asphalt concrete mixture in the molding apparatus during the application of force;
• determining a strain of the asphalt concrete mixture based on the measured heights;
• determining a first material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over first and second stress levels at the first temperature;
• heating the asphalt concrete mixture to a second temperature;
• applying a force to the asphalt concrete mixture in the molding apparatus at a predetermined rate and through a first stress level and a second stress level;
• measuring the applied force and one or more heights of the asphalt concrete mixture in the molding apparatus during the application of force;
• determining a strain of the asphalt concrete mixture based on the measured heights at the second temperature;
• determining a second material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over the first and second stress levels at the second temperature, and
• predicting a third temperature at which a third material characteristic occurs from the from the material characteristics determined at the first and second temperatures.

A method for predicting a temperature at which a certain material characteristic occurs for an asphalt concrete mixture, the method comprising the steps of:

• heating the asphalt concrete mixture to a first temperature;
• placing the asphalt concrete mixture into the molding apparatus;
• applying a force to the asphalt concrete mixture in the molding apparatus in a first predetermined loading sequence through first and second stress levels;
• measuring the applied force and one or more heights of the asphalt concrete mixture in the molding apparatus during the first predetermined loading sequence;
• determining a strain of the asphalt concrete mixture based on the measured heights;
• determining a first material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over the first and second stress levels;
• applying a force to the asphalt concrete mixture in the molding apparatus in a second predetermined loading sequence through third and fourth stress levels;
• measuring the applied force and one or more heights of the asphalt concrete mixture in the molding apparatus during the second predetermined loading sequence;
• determining a strain of the asphalt concrete mixture based on the measured heights;
• determining a second material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over the third and fourth stress levels, and
• predicting a third temperature at which a certain third material characteristic occurs from the results of the first and second predetermined loading sequences.

A method for determining a material characteristic of asphalt concrete mixtures during production of asphalt concrete mixtures, the method comprising the steps of:

• heating the asphalt concrete mixture to a first temperature;
• placing an asphalt concrete mixture into the molding apparatus;
• applying a force to the asphalt concrete mixture in the molding apparatus in a predetermined loading sequence in which different forces are applied to the asphalt concrete mixture to impart different heights to the asphalt concrete mixture in the molding apparatus and through predetermined first and second stress levels;
• measuring and recording the applied forces and heights of the asphalt concrete mixture in the molding apparatus during the loading sequence;
• determining a strain of the asphalt concrete mixture in the molding apparatus based on the measured heights, and
• determining a material characteristic of the asphalt concrete mixture by calculating a slope of a stress-strain relationship over the first and second stress levels.

A method for predicting a material characteristic of an asphalt concrete mixture, the method comprising the steps of:

• heating the asphalt concrete mixture to a first temperature;
• placing an asphalt concrete mixture in a molding apparatus, the molding apparatus having a moveable end plate;
• applying a force to the asphalt concrete mixture in the molding apparatus at a predetermined rate and through a first stress level and a second stress level;
• measuring the applied force and one or more heights of the asphalt concrete mixture in the molding apparatus during the application of force;
• determining a strain of the asphalt concrete mixture based on the measured heights;
• determining a first material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over first and second stress levels at the first temperature;
• heating the asphalt concrete mixture to a second temperature;
• determining a second material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over the third and fourth stress levels, and
• predicting a third material characteristic at a third temperature from the results of the first and second temperatures.

A method for predicting a material characteristic of an asphalt concrete mixture, the method comprising the steps of:

• heating the asphalt concrete mixture to a first temperature;
• placing the asphalt concrete mixture into the molding apparatus;
• applying a force to the asphalt concrete mixture in the molding apparatus in a first predetermined loading sequence through first and second stress levels;
• measuring the applied force and one or more heights of the asphalt concrete mixture in the molding apparatus during the first predetermined loading sequence,
• determining a strain of the asphalt concrete mixture based on the measured heights;
• determining a first material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over the first and second stress levels;
• applying a force to the asphalt concrete mixture in the molding apparatus in a second predetermined loading sequence through third and fourth stress levels;
• measuring the applied force and one or more heights of the asphalt concrete mixture in the molding apparatus during the second predetermined loading sequence;
• determining a strain of the asphalt concrete mixture based on the measured heights;
• determining a second material characteristic of the asphalt concrete mixture by calculating a slope of the stress-strain relationship over the third and fourth stress levels, and
• predicting a third material characteristic at a third temperature from the results of the first and second predetermined loading sequences.