| Ceramsite concrete with fly ash is a kind of concrete which is made up of ceramsite instead of traditional crushed stone and a certain proportion of fly ash.Because of its relatively low apparent density,it is regarded as a kind of lightweight aggregate concrete.In this paper,theoretical analysis,experimental research and finite element numerical simulation are used to study the fracture mechanics parameters of ceramsite concrete with fly ash and its influence on the fatigue life of pavement.Through the above research and analysis,in order to further improve the ceramsite concrete with fly ash mechanical properties,fracture mechanics parameters as well as its fatigue life of pavement concrete,to guide the fatigue life prediction of ceramsite concrete pavement with initial cracks,and the practical engineering application of ceramsite concrete.In this paper,the selection of mixing equipment,the forming process of mixing and specimen vibration and its optimum time are put forward.The compressive strength,flexural strength,fracture toughness and fracture energy tests were carried out to study the strength growth law and the fracture mechanics parameters of ceramsite concrete with fly ash.It is found that the mechanical parameters of ceramsite concrete as pavement concrete can meet the specification requirements and have a considerable amount of surplus value.However,the flexural strength of ceramsite concrete is not high,it is easy to cause damage and the formation of defects in the early age and the use of the process.In addition,the study found that with the increase of standard curing condition,the ultimate value of the fracture toughness,unstable fracture toughness and fracture energy are larger,the ability to resist crack propagation of concrete structure is stronger。So people need as far as possible to make the newly paved ceramsite concrete pavement under standard curing conditions,to ensure the supply of temperature and humidity,and as far as possible to extend the maintenance time.In this paper,the numerical simulation of three point bending beam with single side notch of ceramsite concrete is carried out by adopting the finite element software of ABAQUS6.11 edition based on extended finite element method and combined with the experimental parameters.And in this paper,on this basis,the stress intensity factors of ceramsite concrete with fly ash pavement with initial cracks at different curing ages are analyzed.The results show that the stress intensity factor increases with the increase of curing age and pavement modulus,and the ultimate anti cracking ability of the road slab is determined by the coupling effect of stiffness deterioration and toughness strengthening.Through theoretical analysis,the author connects the stress intensity factor with the fracture toughness value to study the fatigue life of the pavement with initial crack,and estimate the fatigue life of the pavement with initial cracks under different curing ages.In order to prevent the spread of disease in the early stage by the planned maintenance and repair,because it can affect the normal use of the road,reduce its service life and increase the difficulty and cost of repair.And it provides the theoretical basis for the design,maintenance,repair and replacement of the ceramsite concrete pavement. |
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