In order to compare the properties of modified asphalt with conventional processes, the formulations used were identical. The first way is to use the stabilizer to join the way for the shear, shear rate and shear SBS rate is exactly the same. Cut the time for 15 min and then change to stir. Mixing time is 2h. The modified bitumen was then analyzed and the stabilizer was added at one time.
The second way is to add 1/2 of the stabilizer by shearing. Stir and cut for 1 h and then add the remaining part of the stabilizer, two times the time to join the stabilizer for 1h.
The third way to join the stabilizer by cutting 1/3, after two times the time to join the stabilizer for 30min, plus stabilizer after stirring 1h.
Softening point is the measure of the high temperature properties of asphalt. It is generally believed that the higher the softening point of asphalt, the better the high temperature performance of asphalt, the stronger the resistance of asphalt pavement to rutting resistance. For heavy traffic asphalt This is a more recognized concept. However, for modified asphalt, because the softening point of the test process, the small ball in the course of the test path and heavy asphalt different. In the heavy asphalt, when heated to a certain temperature, the asphalt even softening, small ball under the action of gravity, slowly sliding in the softened asphalt, and then through the asphalt film, the ball in the gravity and water buoyancy And the metal plate is relatively rapidly contacted to obtain a measured value of the softening point. In the determination of modified asphalt softening point, because the asphalt added SBS and other powder components, because the thermal conductivity of rubber is lower than the thermal conductivity of asphalt, so the modified asphalt thermal conductivity is also lower than the heavy asphalt Thermal Conductivity. At the same time, the crosslinking reaction between asphalt and asphalt occurred between the asphalt molecules and SBS due to the addition of stabilizers in the modified asphalt, so that the crosslinked network was formed in the modified asphalt. In this modified asphalt, part of the free asphalt has not occurred in the free asphalt has reached softening, the ball slowly sliding into the softening of the asphalt, but the existence of cross-linked network and prevent the ball sliding, so the process of small ball falling From time to time through the asphalt material, but was modified asphalt wrapped in the fall. In this fall process, the power of the left and right around the ball not only gravity, water buoyancy, as well as SBS cross-linked network on the ball drop resistance, so the ball falling time longer in the ball falling Time, the softening point can even increase about 30 ℃. So some researchers believe that the softening point of modified asphalt is not a practical sense of softening point. However, the author thinks that the softening point is also related to the high temperature properties of modified asphalt, and the decrease of thermal conductivity is beneficial to delay the influence of high temperature. So the softening point determination is still meaningful. While observing the whereabouts of the ball to a certain extent, can determine the development of cross-linked network. So I would like to study the use of modified asphalt softening point of semi-modified asphalt high temperature properties.
Under the same formulation, the softening point of the modified asphalt increases with the increase of the number of stabilizers. Especially in three times to join the stabilizer, softening point even more than a stable addition of 15 ℃.
And with the penetration rate, regardless of the stabilizer to join several times, the penetration of the data changes are basically within the error range. For the 5 ℃ ductility, with the increase in the number of stabilizers, 5 ℃ extension slightly reduced, but the modified asphalt 5 ℃ ductility are more than 40cm, from the aging of the film oven after the delay data can be seen, with the stability The increase of the number of times of the addition of the stabilizer increases the post-aging degree of the film oven, which indicates that the increase of the number of stabilizers is beneficial to improve the post-
From the storage stability, it can be seen that the absolute value of the segregation softening point of the modified asphalt increases with the increase of the number of stable home additions, which indicates that the increase of the number of stabilizer addition is not conducive to the storage of modified asphalt, Segregation.
This is because when the stabilizer is added, the stabilizer colleague reacts with the asphalt or SBS because the stabilizer is suitable and the active site in the SBS and asphalt systems is substantially selective and substantially at the same time. And the addition of stabilizer, the first time to join the stabilizer, because the amount of stabilizer is not enough, so the strongest activity and the strongest point of the first combination, in the second time to join the stabilizer, stabilizer in the new Crosslinking point cross-linking. Three times to join the choice of more reactive, and more stable cross-linking, the network is mainly short-chain network, the nature of more stable, so the film oven after the high degree of extension, and bake because the network-intensive, cross-linked more, so bake Before the degree of decline is low. This is the more the number of times to join, the higher the softening point of the modified asphalt, the lower the latitude before aging, and the higher the delay after the aging of the film oven.