In this paper, two main testing methods for asphalt and polymer-modified asphalt are introduced in detail: low-temperature cohesiveness test and segregation performance test. The adhesion properties of asphalt and aggregate under low temperature conditions, as well as the compatibility and segregation degree of modified asphalt were evaluated through test procedures, instruments and equipment, and calculation methods. These tests have important reference value for the study of asphalt properties and the selection of modifiers.
This test method is used to evaluate the adhesion performance of asphalt or modified asphalt to aggregate under low temperature conditions. Through the vibration and fall of the gravel after the impact of the steel plate under the specified conditions, its bonding ability is evaluated, which is often used in the selection of asphalt pavement materials in low temperature environments. The standard test temperature is -18°C.
Steel plate – 200 mm × 200 mm, 2 mm thick, with a sealing frame 8 mm high and 5 mm wide on the edges.
Steel balls – weight 500g ±18g.
Iron frame - the top of the shelf is set on a platform at a height of 500mm from the steel plate.
Refrigerator – for cryogenic cooling.
Cement concrete cushion block - size greater than 200mm, used to fix the steel plate during the test.
Preparation - build the iron frame as required, arrange the screened and dried gravel on the preheated steel plate, and control the thickness of the asphalt sample at 1mm. The test material is heated in an oven at 60°C and then cooled in a refrigerator at -18°C for more than 12 hours.
Impact test - the specimen is taken out of the refrigerator, the steel plate gravel side is facing down, and the steel ball falls freely from a height of 500mm, and the gravel vibrates and falls.
Result calculation
The percentage of the amount of vibrated gravel in the total quantity was calculated as the evaluation index of low-temperature adhesion between asphalt and aggregate.
This method is based on international standards and is particularly suitable for evaluating the performance differences of different modifiers at low temperatures. Through this test, the ratio of asphalt to aggregate can be optimized to ensure the adhesion of pavement materials at low temperatures.
This method is used to evaluate the segregation properties of polymer-modified asphalt and to test the compatibility of modifiers with asphalt matrices. This test method can effectively predict the stability and uniformity of polymer-modified asphalt during construction.
Softening point meter – used to detect the softening point of asphalt.
Standard sieve (0.3 mm) – used to screen bitumen samples.
Aluminium tube – for bitumen samples, 25 mm diameter and 140 mm length.
Oven and refrigerator – used to heat and cool the sample, respectively.
Standard Specimen Cup – used to hold the thawed specimen for subsequent testing.
SBS/SBR polymer modified bitumen
The asphalt sample was heated and poured into an aluminum tube, the nozzle was sealed and heated in an oven at 163 °C for 48 hours. After cooling, the aluminum tube was cut into three sections, and the softening points of the top and bottom samples were tested separately, and the segregation was calculated from the difference.
PE/EVA polymer modified asphalt
The asphalt sample was heated to 135°C, poured into a standard sample cup, and allowed to stand for 24 hours, followed by observation of the surface and bottom consistency of the sample, and the segregation of the asphalt polymer was recorded.
Polymer-modified bitumen can cause segregation in high-temperature environments, especially during stop mixing or cooling. By testing the differences in softening points, the compatibility of different polymer systems can be evaluated, the ratio adjustment can be guided, and the material selection in construction can be optimized.
The above two test methods were used to evaluate the adhesion properties of asphalt in low temperature environment and the segregation properties of polymer-modified asphalt, respectively. Through scientific testing processes and calculation methods, these tests provide a key technical basis for the selection of asphalt materials, and ensure the stability and durability of road paving materials in different environments.