As an important road pavement material, asphalt has a direct impact on the service life and driving safety of the road. As a form of asphalt, emulsified asphalt is widely used in the field of pavement maintenance and construction. In order to ensure the quality and suitability of emulsified asphalt, it must be rigorously tested. In this paper, the principles, methods and steps of the emulsified asphalt particulate ion charge test and the emulsified asphalt demulsification speed test will be introduced in detail.
The emulsified asphalt particulate ion charge test is mainly used to detect the charge properties of the particles' ions in the emulsified asphalt, that is, to determine whether the emulsified asphalt belongs to the cationic type or the anionic type. Different types of emulsified asphalt are suitable for different construction environments, so it is important to know the charge properties for asphalt applications.
Beaker – 200 mL or 300 mL
Electrode plates - copper electrode plates, two pieces, size 100mm×10mm×1mm
DC power supply – 6V
Sieve - sieve hole 1.18mm
Other materials – gasoline, lotions, etc
Preparation
First, the emulsified asphalt sample was filtered through a 1.18mm pore size sieve to ensure that the sample was pure and free of impurities. The electrode plates are then washed, dried, and fixed on a frame with a spacing of about 30 mm. Finally, the electrode plate is immersed in a 200mL or 300mL beaker, and the emulsified asphalt liquid level should cover the electrode plate by at least 3cm.
Test procedure
1. Inject the filtered emulsified bitumen sample into the beaker to ensure that the liquid level is submerged in the electrode plate.
2. Connect the two electrode plates to the positive and negative poles of the 6V DC power supply respectively, turn on the power supply and press the stopwatch at the same time.
3. After 3 minutes, turn off the power and remove the electrode plate.
4. Observe the electrode plate, if a large number of asphalt particles are attached to the negative plate, it means that the emulsified asphalt is cationic; If a large amount of bitumen particles are attached to the anode plate, it is anionic.
The charge properties of the particles in emulsified asphalt determine the category of emulsified asphalt: cationic emulsified asphalt is positively charged, and anionic emulsified asphalt is negatively charged. In this test, the motion of asphalt particles under electric field conditions is simulated, and the charge properties of the particles are judged by the adsorption behavior of the particles on the electrode plate. The method is intuitive, easy to operate, and suitable for the preliminary classification of various types of emulsified asphalt.
The demulsification rate of emulsified asphalt directly affects the mixing stability in construction. This test is used to identify the emulsified asphalt as fast cracking type (RS), medium crack type (MS) or slow cracking type (SS), so as to provide important technical parameters for construction personnel and ensure the mixing efficiency and stability during the construction process.
Mixing pot – the capacity is about 1000mL
Balance - inductance not more than 0.1g
Standard sieve - the sieve hole is 4.75mm, 2.36mm, 0.6mm, 0.3mm, 0.075mm
Mineral material - stone chips with a particle size of less than 4.75mm used in road engineering
Other materials – distilled water, beakers, graduated cylinders, stopwatches, etc
Preparation
According to the actual situation of the project, aggregates with different particle sizes are graded through standard screening and mixed into two groups of standard graded ore (200g per group). Wash and dry the mixing pot.
Test procedure
The first set of specimens is mixed
Place 200g of ore in group A in a mixing pot and mix evenly. For cationic emulsified asphalt, add 5mL of distilled water and mix well, and then add 20g of emulsified asphalt; For anionic emulsified bitumen, 20g of emulsion is added directly. Use a metal spoon to mix at a speed of 60r/min for 30 seconds to observe the uniformity of mixing.
The second group of specimens is mixed
After mixing 200g of ore in group B with 30mL of distilled water, 50g of emulsified asphalt was added, and the mixture continued at a speed of 60r/min for 1 minute to observe the uniformity after mixing.
According to the uniformity of the two groups of mineral materials after mixing, the demulsification speed of the emulsified asphalt is determined.
The test simulates the mixing process of emulsified asphalt and mineral material in the construction process, and judges the demulsification time of emulsified asphalt to determine its suitable application scenario. Fast-cracking asphalt is suitable for scenarios that require rapid solidification, medium-crack asphalt is suitable for general paving operations, and slow-cracking asphalt is suitable for processes with less time requirements. Through this test, the construction personnel can reasonably arrange the construction steps according to the demulsification speed of the asphalt and improve the construction efficiency.
The particulate ion charge test and demulsification speed test of emulsified asphalt are important means to judge the properties of asphalt. These two tests provide important quality inspection methods for the construction unit to ensure the applicability and performance stability of the emulsified asphalt during the construction process. Through reasonable testing, the application of asphalt in road construction can be better controlled, so as to improve the quality and service life of the road.