Sensitivity Analysis of FAARFIELD Rigid Airport Pavement Thickness Determination

FAARFIELD is a common mechanistic-empirical software that uses a combination of layered elastic and finite element methods for the determination of rigid aircraft pavement thickness. The primary input parameters are the aircraft type, mass and departures, concrete flexural strength, sub-base material and thickness, as well as subgrade support characteristic. A parametric sensitivity analysis, including three common commercial aircraft and four subgrade conditions, determined that concrete thickness was most sensitive to concrete strength and aircraft mass. The concrete thickness was least sensitive to the sub-base material and thickness and was moderately sensitive to the subgrade condition and aircraft departures. These relative sensitivities were consistent when the results were analysed based on average percentage change in concrete thickness, the average slope of lines of best fit for normalised parameter values and the coefficients of a numeric linear regression for concrete thickness. It is recommended that designers focus their attention on accurately estimating realistic concrete strength and aircraft mass values, as these parameters had the greatest influence on concrete thickness.

Comparative Study on Microwave Absorbing Heating Characteristics and Microwave Deicing Performance of Airport Pavement Modified Concrete

In this paper, the airport pavement concrete has been taken as the main research object, three kinds of absorbing materials, namely silicon carbide (SiC), iron oxide (Fe3O4) and graphite, have been respectively mixed into the concrete, and an open microwave testing system has been established. Based on this system, the basic mechanical properties, microwave heating characteristics, microwave deicing effect and its influencing factors of modified concrete are systematically studied. In addition, a comparative analysis of the influence mechanism of different absorbing materials on the strength and absorbing performance of pavement concrete is carried out. The results showed that the addition of SiC, Fe3O4, and graphite could effectively enhance the microwave effect of pavement concrete, and the more the addition, the more obvious the improvement. Furthermore, under the same mixing amount, the degree of improvement of microwave deicing performance of each absorbing material from large to small is graphite, Fe3O4, SiC. However, the addition of graphite will form several weak links in concrete, thereby reducing its overall mechanical properties. SiC can slightly improve the mechanical properties of pavement concrete, but it has no significant effect on the microwave absorption properties. With the addition of Fe3O4, the strength of concrete changes little, and the effect of microwave absorbing heating and microwave deicing is remarkable. In general, the comprehensive performance of microwave deicing of Fe3O4 modified concrete is optimal. This study has high scientific and practical significance, and can be widely applied to deicing projects on airports and high-grade highways.

Study of Structural Characteristics of Asphalt Overlays on Airport Pavement with Damaged Load Transfer Efficiency of Joints

In this paper, the real joint load transfer efficiency of airport pavement is calculated by combining the results of airport pavement deflection detection and ground-penetrating radar detection. Spring elements are used to simulate the actual load transfer efficiency of joints in ABAQUS. The impact of different asphalt overlays on the stress state of the critical point in the pavement is analyzed by the airport cement concrete pavement model. The result shows that adding a thin stress-absorbing layer with fine-graded and low modulus can effectively disperse the load transferred from the asphalt pavement to the cement pavement and the stress concentration at the joint under the asphalt overlay. Compared with airport pavement without a stress-absorbing layer, the tensile stress and shear stress at the critical point in the airport pavement asphalt overlay decreased by 24.62% and 22.49%, respectively. Therefore, the combination of the high-modulus upper layer and low-modulus lower layer can effectively reduce the tensile stress and shear stress at the critical point. In addition, increases in the thickness of the asphalt overlay can effectively improve the stress state at the critical point. When the thickness of the asphalt overlay changed from 13 cm to 21 cm, the maximum tensile and shear stress decreased by 8.82% and 8.92%, respectively. Finally, based on the analysis of the numerical simulation and field test verification, the optimal airport pavement asphalt overlay scheme is proposed.