FOUNDATIONS FOR FLEXIBLE PAVEMENTS

FLEXIBLE PAVEMENTS HAVE IN RECENT YEARS BEEN SUBJECTED TO WHEEL LOADS OF INCREASING MAGNITUDE. EXPERIMENTS INDICATE THAT FAILURES ARE PRIMARILY DUE TO PROGRESSIVE PLASTIC DEFORMATION OF THE FOUNDATION WHICH, WITH SUFFICIENT REPETITIONS, CAUSES EXCESSIVE DEFLECTION AND BENDING OF THE BASE AND PAVEMENT. THE REPORT INCLUDES (1) A DISCUSSION OF THE VARIOUS TYPES OF PAVEMENT DEFLECTION, (2) A DESCRIPTION OF ELECTRIC GAUGE EQUIPMENT FOR MEASURING THE DEFLECTION OF PAVEMENTS UNDER BOTH STATIC AND MOVING WHEEL LOADS, (3) A DESCRIPTION OF THE CALIFORNIA BEARING RATIO TEST AND A DESIGN CHART FOR USE WITH THIS TEST, AND (4) A SUMMARY OF THE DEFLECTION AND TRAFFIC TESTS MADE ON A SPECIAL RUNWAY TEST SECTION WHICH WAS CONSTRUCTED AT A WESTERN AIRFIELD BY THE U. S. ENGINEERS FOR CHECKING THE DESIGN CRITERIA FOR HEAVY WHEEL LOADS. /AUTHOR/