Fatigue of Concrete Beams and Slabs. Cooperative Evaluation of Mn/Road TestResults to Illinois Conditions

摘要

IDOT Mechanistic Based Design Procedure was used to evaluate the performance ofconcrete pavements being tested in Mn/ROAD. To accurately evaluate the probable performance of the pavements, fatigue characteristics of concrete used in Mn/ROAD had to be determined. Fatigue tests were run on simply supported beams, fully supported beams and fully supported slabs to evaluate the fatigue behavior of concrete using the different types of specimens. Results show that when interpreted in the conventional manner using Wholer diagram, the fatigue responses were the same with all three specimen types. However, the strength of the concrete at first crack was about 30 percent higher in the fully supported slabs than for the simply supported beams. The slab specimens also showed a much longer performance life between first crack and full cracking than the beam specimens. These results indicate a significantly longer fatigue life for the slabs than predicted using the strength data from simple beams. When the findings were applied to the concrete pavements in Mn/ROAD, using the IDOT Mechanistic Based Design Algorithms, the conclusion was that the pavements should not have failed. Results from Mn/ROAD show no evidence of structural distress at this time, thus partially validating the IDOT Mechanistic Based Design Procedure.