The Bureau of Yards and Docks and the Bureau of Aeronautics of the Navy Department jointly sponsored an extensive investigation of concrete and bituminous-surfaced airfield pavements at more than 40 Naval and Marine Corps Air stations. This involved making more than 3000 plate loading tests ranging up to 75,000 lb. maximum loads, also taking and testing an approximately equal number of samples of subgrades and pavement components.

The objectives of this investigation were: (a) to obtain directly the maximum safe wheel-load capacities of the pavements at the specific fields, (b) to obtain basic information of value in estimating the wheel-load capacities of pavements at other fields not included in the study, and (c) to obtain basic information of value in checking current design procedures and possibly developing new design procedures and methods of construction.

This paper is primarily concerned with one phase of the project, namely, field loading tests and factors which influence the loading test data.

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 undisturbed subgrade samples and for both base course, sub-base and subgrade materials, density and moisture relations, Atterburg limits, and grain size. Asphalt stability and other tests are made with the surfacing materials. 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 and subgrade properties on the bearing value of both the pavement and the subgrade.