Experimental Study On Toughness And Tenacity Of Asphalt

The test on toughness and tenacity of asphalt was first proposed by Japan, which is a better approach to evaluate the effect of modified asphalt. According to the standard, the test temperature is 25℃ and at a rate of 500mm/min.After test, we can get toughness and tenacity two parameters, toughness reflects the maximum tensile deformation of asphalt, tenacity can measure asphalt in the process of tensile delayed fracture ability after yield and the ability of resistance to fracture. Common asphalt and SBR modified asphalt materials, in the process of toughness and tenacity test, at the start of the test, load quickly increased to maximum load, then the load decreased approximately linearly, then appear a long asphalt sample deformation stage, finally the asphalt sample fracture. However, during the test on tohghness and tenacity of asphalt, for a variety of other modified asphalt materials, the curve is very different from the standard, and the standard can not be used in evaluation method, such as appear a double peak and yield stage, which makes it difficult to obtain accurate toughness and tenacity two parameters if adopt the measure of standard.In the thesis, according to the test standard, through the test on toughness and tenacity of asphalt for the common matrix asphalt, ordinary rubber modified asphalt, SBS modified asphalt and high adhesion compound rubber modified asphalt, consider different Load-deform curve shape characteristic, the test can be divided into cohesiveness deformation stage (includes elastic deformation, plastic deformation), tensile deformation stage (includes elastic-plastic deformation, yield and fracture process), and proposed evaluation on toughness and tenacity of asphalt, such as cohesiveness, tenacity ratio, maximum adhesion force, the corresponding displacement of maximum adhesion force, cohesiveness modulus, maximum tensile, the corresponding displacement of maximum tensile, total displacement of the test.In the cohesiveness deformation stage, we can get maximum adhesion force and tensile strength capacity in this stage, namely cohesiveness modulus. For the asphalt material that force has no obvious decline after maximum adhesion force, at the maximum adhesion force do vertical line intersects with the horizontal axis in the curve, the cohesiveness of asphalt is twice the area that is enclosed by the vertical line, the horizontal axis and the left side of the curve. Through the cohesiveness we can calculate the tenacity. In the tensile deformation stage, the force maybe appear the phenomenon of the increase for some modified asphalt (especially high adhesion compound rubber modified asphalt), after the maximum adhesion force, asphalt appear fracture, at last of the test we can get total displacement.Last, to obtain the impact about test temperature on toughness and tenacity performance of asphalt, the thesis makes test on toughness and tenacity with five kinds of non-standard temperature, which are 5℃,15℃,35℃,45℃,55℃. The results show that the temperature has a great influence on toughness and tenacity of high adhesion compound rubber modified asphalt. At a low temperature, the asphalt mainly shows cohesiveness, has little tensile deformation and tenacity is small, the curve showed a single peak. When at a high temperature, tenacity increase, and the force show a double peak in the curve, total displacement increases with increasing temperature.