Evaluation of airfield concrete block pavements based on 3-D modelling and plate loading test

Abstract

Concrete pavements are commonly used in some areas of airfields such as aprons. Repairing these pavements is costly and time-consuming, and it also disrupts flight operations. The use of concrete block pavement is a more suitable option at aprons. Fewer studies have been done on this type of pavement in the airfields than on roads. For further studies, the performance of this pavement was examined by making a 3D model and a test track with dimensions of 2 m × 2 m. This sample was composed of subgrade, subbase, base and Cement-Treated Base (CTB) layers, with 15 cm thickness, for each layer, bedding sand with 3 cm thickness and a Unipave-shape (zig-zag) concrete block pavers with 8 cm thickness and herringbone pattern. Then their quality was controlled, based on Federal Aviation Administration (FAA) regulation. At the next step, Plate Load Test (PLT), was conducted on this sample. For this purpose, a setup including a concrete foundation and a reaction beam was built. For the first time in related research, several 3D models of concrete block with all its angles and corners representing their actual dimensions were made using ABAQUS software. The field studies' experiments result on the materials were used to define the characteristics of the model components, and then the force–deflection curve, as a guidance chart was presented. Studies have shown differences in opinion about the amount of elastic modulus of block and jointing sand. The 3D model analysis result showed that the elastic modulus of the concrete block surface could be taken into account at 2000 MPa to achieve the most coordination between finite element analysis and PLT results. Then, the curve of the allowable number of repetitive loads (N) vs. wheel load pressure was illustrated by selecting the horizontal strain and stress at the bottom of CTB as the failure criterion. Moreover, analysis of the allowable number of load repetitions through Miner’s theory indicated that the equations that calculate N, based on the horizontal stress, achieve more consistent results relative to corresponding equations calculated based on the horizontal strain. According to finite element analysis results, by increasing load pressure, the interlocking of Airfield Concrete Block Pavement (ACBP) improved and the rate of decreasing of the allowable number of load repetitions declined.