Publish Time: 2020-06-22 Origin: Site
Modified asphalt has been an area where the MATC project investigates implementation challenges and shares experiences with the asphalt community. The asphalt binder tester is involved in several field projects evaluating modified asphalt binders and mixtures. The main challenge in describing the properties of modified asphalt binders involves a suitable asphalt binder tester test method. Observations from field studies indicate that the concentric cylindrical geometry provides a promising tool for characterizing the rheological properties of modified asphalt binders.
1.the coherence of the procedure of asphalt binder tester
2. Solvent extraction
3. Adhesive ignition
Asphalt binder tester provides a means for quantifying the low temperature crack resistance of asphalt binders. This test is used for asphalt binders with bending stiffness values from 20 MPa to 1 GPa. The asphalt binder tester consists of a loading frame, a stand, a liquid tank, a data acquisition system, and a test mold. During the test, the deflection at the center point of the beam was measured continuously. The data collected from the asphalt binder tester was used to calculate the m-value and stiffness of the test specimen at 8, 15, 30, 60, 120 and 240 seconds. The asphalt binder tester requires a stiffness and M value of 60 seconds, and critical cracking temperatures derived based on the stiffness values of 8, 15, 30, 60, 120, and 240 seconds.
The direct tensile test results of the asphalt binder tester are related to the ability of the asphalt binder to resist low temperature thermal cracking. Failure stress can be used to determine the critical cracking temperature used. Failure strain can also be used to grade asphalt binders. The test equipment is designed for an operating temperature of -36 ° C to 6 ° C. The displacement sensor is used to measure the elongation of the stretched sample, and its constant elongation is 1mm / min.
The solvent extraction method has been used in the asphalt binder tester for many years, and a corresponding test method has been established. These procedures use different types of solvents to separate the asphalt binder from uncompacted HMA samples. Once separated from the solvent and bitumen aggregate, it is weighed on aggregate, and compared to the initial sample weight and then calculating the percentage difference between the bitumen content. The operator can then graded tests on aggregate. Although these methods are established and proven, it might be worth considering other tests, if the cost of solvent, treatment and disposal is a problem.
The binder ignition method was developed by the National Asphalt Technology Center (NCAT). The asphalt binder tester establishes a standard test method for this program. The asphalt content is determined by the fraction of the binder. 538ºC pitch point temperature furnace heating chamber of a specially designed (1000 ° F) ignition and combustion of bitumen samples loose association. For 1200--1800 g sample, this process takes approximately 30 - 40 minutes for a 3000 g sample, this process is slightly longer. The remaining aggregate is then weighed, the initial and final weights are compared, and the asphalt content is calculated. Sometimes a correction factor is needed to compensate for the small amount of mineral content burned from the aggregate. Aggregate grading was then determined using standard sieve analysis.