Evaluation Of Compaction Uniformity Of Asphalt Mixture Based On Total Reflection Method

For hot-mix asphalt pavement,the compaction uniformity is the key factor affecting the durability of pavement.The traditional pavement compaction uniformity detection method has been unable to meet the increasing requirements of pavement detection due to its shortcomings such as low detection accuracy,slow detection speed and damaged pavement structure.It is urgent to adopt an efficient,accurate and nondestructive method to test the compaction uniformity of asphalt pavement to meet the needs of the rapid development of pavement construction.Three-dimensional Ground Penetrating Radar(3D GPR)technology can obtain the continuous dielectric constant of the whole section of asphalt pavement,which has the characteristics of wide detection range and high working efficiency.It has been widely used in the fields of asphalt pavement thickness detection,density prediction,pavement crack investigation,and the determination of the depth and alignment of bridge slab reinforcement.In this thesis,the reflection amplitude of metal plate and asphalt pavement are collected by 3D GPR.The total reflection method is used to obtain the dielectric constant of asphalt pavement,and the dielectric constant measured by core drilling sampling method and common point method is compared and analyzed.Finally,it is reasonable to select the total reflection method to calculate the dielectric constant of asphalt pavement The uniformity of dielectric constant is evaluated from the standard deviation of local dielectric constant and the uniformity of local dielectric constant.The 3D GPR detection system can continuously obtain the dielectric constant of the detection area,because the core drilling sampling method can not obtain the continuous density of the detection area due to its limitations such as destroying the road surface,so this thesis uses the non kernel densitometer to obtain the density of asphalt pavement,and evaluates its compaction uniformity from two aspects of local coarse segregation ratio and local fine segregation ratio.In order to better evaluate the compaction uniformity of asphalt pavement,the mathematical relationship between dielectric constant and density is established based on electromagnetic mixing theory.In order to solve the problem that 3D GPR can not directly derive the dielectric constant of asphalt pavement,a method to automatically calculate the dielectric constant of asphalt pavement by using MATLAB program is proposed to improve the detection efficiency.Involved in the calculation of the asphalt pavement dielectric constant and the void fraction of whole section continuous fitting analysis,the calculation results show that as to participate in the dielectric constant of radar data,the fitting of dielectric constant and density of empirical formula,the better,so this thesis to determine the 3D GPR is the most accurate method to calculate the dielectric constant with the line width per average seven channels along the detection,Take the average of every 10 data along the detection length direction.Finally,based on the testing experience of 3D GPR and non-core density meter in practical engineering and a large number of relevant research data,this thesis gives a recommended testing method for asphalt pavement construction uniformity detection,which provides a new method for more accurate,rapid,efficient and full-width evaluation of asphalt pavement compaction uniformity detection.