Experimental Study On Optimum Proportioning Of Fiber Fly Ash Asphalt Mixture

Asphalt mixture pavement is widely used in road engineering because of its flat surface,low vibration and comfortable driving.However,pavement rutting,cracking and other phenomena will reduce its service life and endanger highway safety.Therefore,it is very necessary to improve its road performance.Fly ash has been proved as a filler of asphalt mixture to improve its high temperature stability.It has been proved that fiber can be used as admixture and improve its low-temperature crack resistance because of its adsorption and stability to asphalt mixture.Therefore,using fly ash and fiber to improve the road performance of asphalt mixture has become a feasible research direction.In order to clarify the influence law of fly ash and fiber on asphalt mixture and its optimal dosage range,the following research is carried out:（1）the influence law of fly ash dosage on the road performance of asphalt mixture is analyzed through experiments,and the required dosage range and its optimal dosage are determined.（2）Polyester fiber,polypropylene fiber and basalt fiber are mixed into fly ash asphalt mixture respectively.Through the test,the influence law of different fibers on the road performance of asphalt mixture is analyzed,the optimal fiber and the range of content meeting the requirements are judged,and the optimal content is determined.（3）Through the test,the influence law of different mixing sequence,mixing temperature and curing temperature on the road performance of asphalt mixture is analyzed,and the reasonable construction technology is determined.The following conclusions are drawn from the test results:（1）the content range of fly ash meeting the requirements of the test specification is 3.6% ～ 9.3%,and the best content is about 6%.（2）Polyester fiber,polypropylene fiber and basalt fiber can enhance the low-temperature performance of asphalt mixture,but the reinforcement effect of basalt fiber is the most obvious under the same content.The content range of basalt fiber meeting the specification requirements is 0.17% ～ 0.61%,and the best content of fiber is about 0.35%.（3）Dry mixing of fiber and mineral aggregate for 20 s + wet mixing of asphalt for 90 s + wet mixing of fly ash for 90 s.This sequence can effectively disperse the fibers and ensure the uniformity of fibers in the mixture;Within the temperature range required by the specification,the higher the mixing temperature,the better the high-temperature performance,and the lower the mixing temperature,the better the low-temperature performance;In the range of 0 ～ 60 ℃,the curing temperature has no effect on the performance of hot mix asphalt mixture.