Influence Of Hot And Humid Environment Factors On Dynamic Resilience Modulus Of Asphalt Concrete

In the design of old road reconstruction,the direct overlay of asphalt concrete is a relatively common structural reinforcement design.In the current specification,the equivalent resilience modulus of the top surface of the old road is used as the resilience modulus of the reinforced pavement structure,and the dynamic elastic modulus of the old asphalt concrete is not considered,which will affect the service life of the new pavement structure after reconstruction.Therefore,it is of great significance to determine the dynamic resilience modulus of old asphalt concrete for the durability of reconstructed pavement.In this paper,the influence law of dynamic resilience modulus of asphalt concrete in hot and humid environment is studied,and the determination method of dynamic resilience modulus of old asphalt concrete under uniaxial compression is proposed.The aging and dry-wet cycle are used to simulate the natural aging of asphalt pavement in hot and humid areas.The dynamic resilience modulus of the matrix and modified asphalt mixture at different stages is measured,and the master curve is fitted based on the Sigmoidal function.The conclusions are as follows:(1)The asphalt mixture is hardened gradually due to aging,which increases the dynamic resilience modulus gradually.It can increase high temperature deformation resistance and decrease low temperature crack resistance.Under the action of dry wet cycles,the dynamic resilience modulus increases slightly due to the obvious aging effect of asphalt water when the number of cycles is less;As the number of wet-dry cycles increases,the effect of water erosion becomes more prominent,and the attenuation of adhesion between asphalt and aggregate leads to a decrease in the bearing capacity of the mixture,which decreases the dynamic modulus of resilience as a whole.(2)Under the coupling effect of aging and dry-wet cycle,asphalt mixtures that are aged first and then subjected to dry-wet cycles have lower dynamic resilience modulus and worse high-temperature performance.With the aid of indirect tensile test,the size effect of indirect tensile modulus is discussed.Combined with dynamic modulus of resilience of uniaxial compression,the modulus relationship under two different test modes is studied.The conclusions are as follows:(1)The indirect tensile modulus of AC-13 asphalt mixture has a relatively obvious size effect.The size effect is characterized by thickness and the ratio of indirect tensile modulus,and the size effect equation of indirect tensile modulus is established.(2)According to the indirect tensile modulus and uniaxial compression dynamic resilient modulus of the standard size,the modulus linear conversion relationship of the matrix and the modified asphalt mixture under the two test modes is established.(3)A convenient method for determining the dynamic resilience modulus of asphalt concrete core samples with limited thickness is proposed.The indirect tensile modulus measured by the pavement core samples is modified by thickness,and the dynamic modulus of resilience is determined according to the linear relationship between indirect tensile modulus and uniaxial compressive modulus.