Study On Mechanical Properties And Failure Laws Of Ultra-high Performance Pavement Concrete

With the growing serious phenomenon of heavy load and overload,the damage rate and maintenance rate of cement concrete pavement also increase.In order to effectively solve the key technical problems of high strength,high durability and long service life of cement concrete pavement,the research and development of ultra-high performance pavement concrete(UHPPC)technology and its performance research have become the focus of attention of scholars and engineers at home and abroad.In this thesis,through heavy load and acid rain-heavy load environment simulation tests,the attenuation laws of UHPPC’s compressive properties,flexural properties and wear resistance are studied.Combined with CT scanning and SEM observation,the formation and development process of UHPPC cracks are analyzed,and its failure characteristics and deterioration mechanism are explored.Based on the Grey Relational Analysis,the correlation degree between different performances is analyzed,and the performance index of road evaluation is put forward,which provides early technical support for the research and development of UHPPC and practical engineering application,and is of great significance to ensure and prolong the service life of cement concrete pavement.The main conclusions of this thesis are as follows.(1)The performance attenuation law of UHPPC under heavy load is proved.The results show that the compressive strength and flexural strength of UHPPC decrease with the increase of loading stress level,while the wear amount increases with the increase of stress level.Among them,the flexural properties are most obviously deteriorated by heavy load.(2)The performance attenuation law of UHPPC under the combined action of acid rain and heavy load is proved.The results show that the compressive strength of UHPPC increase first and then decreases rapidly with the increase of loading stress level.The flexural strength decreases with the increase of stress level.The wear amount increases with the increase of stress level,and the wear resistance is improved compared with that after heavy load.(3)The failure mode of UHPPC cracks was observed by CT scanning and SEM technology.The results show that cracks change with the change of stress loading level,and the failure proceeds from outside to inside,with the increase of stress level and the number of cracks.Under heavy load,the internal structure of UHPPC is mostly damaged physically,while under acid rain-heavy load,the internal structure of UHPPC is damaged both physically and chemically.(4)Based on the Grey Relational Analysis,the influence relationship between compressive strength,wear amount and flexural strength of UHPPC after deterioration is obtained,which shows that compressive strength of UHPPC has a closer influence on flexural strength than the wear amount.The UHPPC heavy-duty service life and road evaluation index-load stress is put forward.