To provide a modified asphalt composition capable of solving problems of traffic safety and comfortableness, such as splashing water and a hydroplaning phenomenon, which are caused by rain water collected in 'wheel ruts', by improving a paving asphalt mixture so as not to cause the wheel ruts and so as to have excellent fluidity-resisting properties, because asphalt surface layers of important traffic routes are exposed to heavy loads due to the recent traffic situation and therefore the wheel ruts into which the rain water is collected are made on the surfaces, and further capable of meeting such a requirement that environment-friendly treatment of fiberglass-reinforced plastic(FRP) from waste boats, preferably recycling technology therefor, should be developed, because the waste FRP boats used as pleasure-boats, etc., cause environmental problems.

This modified asphalt composition contains a petroleum asphalt, a rubber, a thermoplastic elastomer, and a pulverized material of the FRP obtained from the FRP waste boats in an amount of, preferably, 0.5-1.5 wt.%. The composition clears specification limits designated by the Marshall test and the penetration-mode test, and further enough clears a specification limit designated by the wheel tracking test which proves the fluidity-resisting properties. The modified asphalt composition thus prepared gives a modified paving material which scarcely causes the wheel ruts.