The asphalt content combustion furnace is a key equipment for determining the asphalt content in asphalt mixtures, and its operational standardization directly affects the accuracy and reliability of the test results. The following details the usage from four aspects: preparation stage, operation process, safety precautions, and maintenance:

1、 Preparation stage: Environmental and sample pretreatment

1. Environmental requirements: Choose a well ventilated laboratory, keep it away from flammable storage areas, and equip it with smoke exhaust devices to release harmful gases (such as benzo [a] pyrene) produced during combustion. The room temperature should be stable at 20 ± 5 ℃ to avoid temperature fluctuations affecting weighing accuracy. ​

2. Sample preparation: Samples should be taken according to the "Test Code for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20). The mixture should be crushed to a particle size of<6.4mm and reduced to approximately 1000g using the quartering method. If the sample has a high moisture content, it needs to be dried in advance (to constant weight at 105 ℃± 5 ℃) to prevent moisture from interfering with the combustion process. ​

3. Instrument inspection: Confirm that the power cord of the combustion furnace is not damaged and the temperature control instrument is reset to zero; Clean up residual ash in the furnace and replace it with a new ceramic crucible (to avoid impurity contamination); Verify the electronic balance (accuracy ≥ 0.1g) to ensure weighing error ≤ 0.1%. ​

2、 Operation process: Standardized execution and parameter control

1. Weighing and sample loading: Accurately weigh the sample mass (denoted as m ₁) and lay it flat in a crucible of constant weight, with a thickness not exceeding 2/3 of the crucible height, to avoid accumulation and affect combustion efficiency. ​

2. Furnace entry and heating: Place the crucible lightly in the center of the furnace, close the furnace door and seal it; Start the heating program, set the heating rate according to the standard (usually 5 ℃/min), and finally stabilize at 538 ℃± 5 ℃ (this temperature can decompose asphalt binder). ​

3. Combustion and observation: Continuously observe the state inside the furnace, start timing when a blue flame appears, and maintain the combustion time for no less than 30 minutes until no visible smoke is emitted. If the flame stalls during combustion, it needs to be reignited and the combustion time extended by 15 minutes. ​

4. Cooling and Weighing: After the combustion is completed, turn off the power and wait for the furnace temperature to drop to room temperature. Remove the crucible and place it in a dryer to cool to a constant weight (the difference between two weighings is ≤ 0.1g). Record the remaining mass of the aggregate (denoted as m ₂). ​

5. Calculation result: Asphalt content=(m ₁− m ₂)/m ₁ × 100%, parallel test deviation should be ≤ 0.4%, take the average as the final result. ​

3、 Safety precautions: Risk prevention and emergency response

1. Personal protection: Operators should wear flame-retardant work clothes, heat-insulating gloves, and goggles to avoid high temperature burns or splash injuries; It is prohibited to wear synthetic clothing to prevent static electricity from igniting. ​

2. Equipment safety: Overtemperature operation is strictly prohibited (up to 600 ℃) to prevent deformation of the furnace body; If there is a sudden open flame in the furnace, immediately cut off the power and use a fire extinguisher to extinguish it. Do not open the furnace door to intensify combustion. ​

3. Waste management: The waste residue after combustion should be classified and collected, and treated according to environmental protection requirements to avoid heavy metal or polycyclic aromatic hydrocarbon pollution of the environment. ​

4、 Maintenance and upkeep: Extend lifespan and ensure performance

1. Daily cleaning: After each test, remove the carbonization residue in the furnace and use a soft bristled brush to clean the surface of the heating element to avoid carbon deposition affecting the heat conduction efficiency. ​

2. Regular calibration: Verify the accuracy of the temperature control meter quarterly (error ≤ ± 5 ℃), replace aging heating wires and thermocouples annually, and ensure a stable heating rate. ​

3. Replacement of vulnerable parts: Replace the crucible in a timely manner when cracks appear or the glaze surface falls off to prevent sample leakage; The sealing gasket needs to be updated after aging to maintain the airtightness of the furnace. ​

By strictly following the above details, the accuracy and repeatability of asphalt content testing can be effectively improved, providing reliable data support for pavement engineering quality control.