THE EVALUATION OF WHEEL LOAD BEARING CAPACITIES OF FLEXIBLE TYPES OF PAVEMENT

THE GENERAL PROCEDURE FOR EVALUATING THE WHEEL LOAD BEARING CAPACITIES OF FLEXIBLE TYPES OF PAVEMENTS AT NAVAL AIR STATIONS IS DESCRIBED. THE PROCEDURE INCLUDES PLATE LOADING TESTS, BOTH ON THE PAVEMENT SURFACE AND ON THE SUBGRADE, AND IN-PLACE DENSITY AND MOISTURE TESTS OF BASE COURSE, SUB BASE AND SUBGRADE MATERIALS. LABORATORY TESTS INCLUDE TRIAXIAL TESTS ON UNDISTRUBED SUBGRADE SAMPLES, DENSITY AND MOISTURE RELATIONS, ATTERBERG LIMITS, GRAIN SIZE, ASPHALT STABILITY AND OTHER TESTS. COMPARISONS ARE MADE BETWEEN THE IN-PLACE DENSITIES AND MOISTURE PERCENTAGES OF SUBGRADE SOILS AND THE LABORATORY COMPACTED MAXIMUM DENSITIES AND OPTIMUM MOISTURES OF THE SAME SOILS. THE LIMITATIONS AND APPLICABILITY OF THEORY ARE BEING STUDIED. DATA INDICATE THE RELATIONSHIP BETWEEN BEARING CAPACITY AND TIRE PRESSURE AND ALSO THE RELATIONSHIPS BETWEEN PAVEMENT THICKNESS, BASE COURSE DENSITY, AND SUBGRADE PROPERTIES ON THE BEARING VALUE OF THE PAVEMENT. A CRITICAL STUDY IS BEING MADE OF CERTAIN YARDSTICKS, USED IN PAVEMENT THICKNESS DESIGNS, WHICH INVOLVE THE ASSUMPTION THAT SOFT WET SUBGRADES ARE NORMALLY TO BE EXPECTED UNDER AIRPORT PAVEMENTS IN USE. THUS FAR IN THE STUDY, THE ACTUAL SUBGRADE CONDITIONS AS FOUND, FAIL COMPLETELY TO BEAR OUT THIS ASSUMPTION. /AUTHOR/