Research On Design And Properties Of High Modulus Modified Asphalt

With the increase of traffic volume and traffic load,rutting disease has been more and more serious.High modulus asphalt is needed for rutting pavement,perpetual pavement and airport pavement.High modulus asphalt and asphalt mixture have good rutting resistance,durability and high modulus,adaptable to high traffic volume and traffic load in present road system.High modulus asphalt has become one of the most effective means to reduce pavement rutting.The paper is to develop the high modulus asphalt with high modulus,good rutting resistance and excellent comprehensive performance.Firstly,in order to obtain high modulus asphalt with high performance and low cost,polyethylene and polyproplene,the most common polyolefins,were used as the main materials of high modulus asphalt.The influence of different contents on the performance of polyolefin modified asphalt?POA?was analyzed.The results show that polyolefin can significantly improve the anti-rutting performance of asphalt.Copolymerized polypropylene modified asphalt has better low temperature performance than homopolymerized polypropylene modified asphalt.At low strain?less than 5%?,the fatigue life of POA can reach 20000 times.At higher strain level,polyolefin has opposite effect on asphalt fatigue life.When the contents of polyethylene and polypropylene are both 4%,POA has the best rutting resistance,complex modulus and fatigue life.POA has bad storage stability.Then,improved schemes were provided according to three different theories concerning ehnhancing storage stability.The effects of MAH,PO-MA,S and EVA on the storage stability of POA were tested,and the high temperature performance and fatigue life of thess modified asphalt were analyzed.The EVA has the maximun effect on the storage stability of POA,followed by PO-MA.MAH and S has little effect on the storage stability of POA.The low-temperature flexibility of POA is better after EVA is added.The addition of other components reduces the complex modulus of asphalt at high temperature and low frequency,and has little influence on the complex modulus at low-temperature and high frequency.S and EVA can significantly improve the fatigue life of POA.In order to adapt to the need of engineering application,LDPE,SBS,nano-CaCO₃ and PO-MA+nano-CaCO₃ were adopted to increase the fatigue performance,low temperature performance and aging resistance of POA.The results show that at the strain less than 10%,LDPE and nano-CaCO₃ increase the fatigue life of POA by 1¹.5 times.The rutting resistance of modified asphalt is also improved by adding these materials.The low temperature cracking resistance of POA is enhanced most by adding SBS.The addition of nano-CaCO₃ can significantly improve the aging resistance of POA.Based on these tests and analysis,the self-developed high modulus asphalts?SHMA1 and SHMA2?were made.Asphalt tests and asphalt mixture tests of SHMA were conducted.Results show that SHMA1 belongs to very high modulus asphalt and SHMA2 belongs to extremely high modulus asphalt.The fatigue life at 2.5%strain level of SHMA reaches 27000 times.The fatigue life of SHMA is decreased by 35%after short-term aging.SHMA shows good storage stability.The self-developed high modulus asphalt mixture?SHMM?has excellent rutting resistance at high temperature,good crack resistance at low temperature and good water stability.