Superaccelerated Pavement Testing on Full-Scale Concrete Slabs

Several full-scale rigid pavement slabs were constructed and tested under constant cyclic loading for fatigue. To provide the comparable maximum applied stress to number of cycles to failure ( S-N) relationships for the full-scale field slabs, laboratory beam fatigue testing was conducted before field testing with the use of the same concrete mix designs. The superaccelerated pavement testing technique that was developed at the University of Texas was used in the field. The stationary dynamic deflectometer (SDD) was used to load the full-scale concrete slabs. To monitor the response of the rigid pavements, accelerometers and linear variable differential transformers were installed, and dynamic and permanent displacements of slabs were recorded during the entire testing period. All test slabs reached fatigue failure under the interior loading configuration using the SDD. This field loading system was found to be a practical and effective tool for testing the full-scale rigid pavement system. During fatigue loading, cracks began at the bottom of the slabs at the loading locations and propagated along the bottom of the slab centerline, which was the maximum stress path. Vertical crack propagation at the edge and stress redistribution occurred for the part of the slab's fatigue life. The concept of equivalent fatigue life was applied to correct the effect of the different stress ratios between the field and the laboratory testing. The laboratory beams and full-scale field slabs showed an almost identical S-N relationship after the correction for the variance of stress ratio.