Experimental Study On Flexural And Compressive Properties Of Carbon Fiber Asphalt Concrete Under Different Temperatures And Loading Rates

Asphalt concrete is widely used as an impermeable body structure in water conservancy projects because of its great impermeability and deformation properties.With the continuous development of water conservancy projects in China,more and more hydraulic buildings are being built in areas with complex geological conditions or in seismic zones that cannot be avoided.Therefore,the mechanical properties of hydraulic asphalt concrete need to be improved to meet the design requirements.As a new research direction to improve the mechanical properties of asphalt concrete,the " fiber + asphalt concrete " composite material can use the advantages of carbon fiber such as light weight,high strength,high modulus,durable and not easily affected by the environment,effectively improve the mechanical properties of hydraulic asphalt concrete.Currently,the research on fiber asphalt concrete is mainly focused on road asphalt concrete,while there is a lack of research on hydraulic asphalt concrete.Therefore,it is necessary to investigate the effect of fiber reinforcement on the performance of hydraulic asphalt concrete.In addition,asphalt concrete has obvious temperature sensitivity and rate effect,and changes in temperature and loading rate can lead to differences in its mechanical properties.Therefore,this paper conducts an experimental study on the performance of carbon fiber asphalt concrete in order to investigate the change in performance at different temperatures and loading rates.The main research contents and conclusions of this paper are as follows:(1)As a reinforcing material to improve asphalt concrete,the physical characteristics of carbon fiber determine that it can work synergistically with asphalt to enhance the performance of asphalt concrete.In this paper,the splitting test was used to test the reinforcing effect of carbon fiber on asphalt concrete,and the results of the study showed that the splitting strength of asphalt concrete increased by 52% and the splitting strain increased by 13.1% when the carbon fiber was mixed at 0.3%.(2)By analyzing the bending tests of small beams at different temperatures and loading rates,the stress-strain relationships of carbon fiber asphalt concrete under different environmental conditions are revealed.At the same time,the effects of temperature and loading rate on the flexural tensile strength,maximum flexural tensile strain and flexural deformation modulus of carbon fiber asphalt concrete are revealed,and a model for calculating the bending performance index considering the combined effects of temperature and loading rate is established.In addition,a comprehensive analysis of the flexural properties of carbon fiber asphalt concrete from an energy perspective is carried out by applying the bending strain energy density function.(3)By analyzing uniaxial compression tests at different temperatures and loading rates,the effect of temperature and loading rate on the compressive performance and damage characteristics of fiber asphalt concrete is revealed,with carbon fiber asphalt concrete exhibiting low temperature stiffening and loading rate stiffening characteristics.(4)Uniaxial compression tests based on acoustic emission parameters were carried out to investigate the relationship between damage characteristics and acoustic emission parameters of carbon fiber asphalt concrete.The test results show that the ringing counts and cumulative ringing counts can well reflect the damage characteristics and degree of damage of the material at different loading stages,and the time-accumulated ringing count curve shows an "S" shape under low temperature environment.The combined analysis of the acoustic emission parameters allows for a full description of the damage process of carbon fiber asphalt concrete.