Theoretical maximum relative density and compression test method of asphalt mixture

Asphalt testing ensures the quality and durability of asphalt mixtures by measuring their density, compressive strength and other properties in road construction. Precise test methods, such as solvent methods and thermostatic water tanks, are used to evaluate key material indicators such as aggregate water absorption and porosity to optimize pavement use.

Theoretical Maximum Relative Density Test of Asphalt Mixture (Solvent Method)

Purpose and Scope of Application

This method is suitable for determining the theoretical maximum relative density of asphalt mixture by solvent method, and is mainly used for calculating porosity and compaction degree in asphalt mixture mix design, road condition investigation and pavement construction quality management. This method is not suitable for asphalt mixtures with aggregate water absorption of more than 1.5%.

Instruments and materials

  • Thermostatic sink – control the water temperature at 25°C ± 0.5°C.

  • Balance - the accuracy is not less than 0.1g.

  • Wide-mouth volumetric flask – 1000ml, with grinding stopper.

  • Solvent – trichloroethylene.

  • Thermometer – accuracy 0.5°C.

Methods and Steps:

Preparation – Obtain sufficient samples of asphalt mixture according to different sampling methods (e.g. mixing building, material truck, paving site, drill core, etc.). The quality of the specimen shall meet the standard.

Test procedure

   1. Weigh the mass of the dried volumetric flask.

   2. Fill the volumetric flask with solvent and hold it in a thermostatic water tank at 25 °C for 15 min before weighing.

   3. Add an appropriate amount of asphalt mixture to the volumetric flask, and weigh the total mass of the mixture and the bottle.

   4. Add solvent and immerse the bottle in a thermostatic water sink and gently shake the mixture to ensure that the bubbles are completely discharged.

   5. After the asphalt is completely dissolved, add more solvent until the volumetric flask is full and weigh the total mass.

compute

The theoretical maximum relative density of the asphalt mixture is calculated according to the standard formula. The trial was repeated twice, and the average was taken as the final result.

Uniaxial compression test of asphalt mixture (cylindrical method)

Purpose and Scope of Application

This method is mainly used to determine the compressive resilience modulus and compressive strength of hot-mix asphalt mixture. The test results can provide important parameters for asphalt pavement design and construction. The standard temperature is 20°C or 15°C and the loading rate is 2mm/min.

Instruments and materials

  • Materials testing machines – maximum loads between 20% and 80% of the measuring range, with spherical bearings and incubators with accurate temperature control.

  • Deformation measurement device - pressure plate, dial gauge, etc.

  • Thermostatic water tank – keeps the test piece warm at the test temperature.

  • Thermometers, balances, calipers, etc.

Methods and Steps:

1. Specimen preparation – The specimen should meet the standard size requirements, usually a cylinder with a diameter of 100mm and a height of 100mm. The specimen should be left for 24 hours after molding and kept warm for at least 2.5 hours before the test.

2. Compressive strength test step - the specimen is placed on the press, and the loading rate is carried out according to the loading rate of 2mm/min until the specimen is broken, and the maximum load value is recorded.

3. Compressive resilience modulus test steps - according to the results of the compressive strength test, set 10 levels of loading, load step by step, and record the deformation and load data of each level.

Results & Reports

The test results include compressive resilience modulus and compressive strength. Each group of specimens is subjected to multiple tests, and the average value is taken as the final result.

summary

Asphalt testing is designed to evaluate the physical properties and durability of asphalt mixtures through a variety of test methods to ensure their high-quality performance in road construction. Through the detection of key indicators such as density, compressive strength, water absorption and porosity, the ratio of materials and construction technology can be effectively optimized, so as to improve the service life and safety of the pavement.


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