Accession Number : AD0250648

Title :   THE MECHANICAL SUBGRADE A PAVEMENT LOAD, TRANSMISSION TESTING DEVICE

Corporate Author : NAVAL CIVIL ENGINEERING LAB PORT HUENEME CALIF

Personal Author(s) : LOWE,R.J.

Report Date : 18 OCT 1960

Pagination or Media Count : 10

Abstract : A UNIQUE PIECE OF PAVEMENT-TESTING EQUIPMENT CALLED THE MECHANICAL SUBGRADE HAS BEEN INSTALLED AT NCEL AND GIVEN LOAD AND CALIBRATION TESTS.THE DEVICE WAS BUILT BY THE FAA (FORMERLY CAA( DURING THE LATE 1940'STO OBTAIN BASIC INFORMATION ABOUT FLEXIBLE PAVEMENT DESIGN. IN THE DEVICE A TEST PAVEMENT IS SUPPORTED ON A FLOORING OF SMALL STEEL PLATES MOUNTED ON PLUNGERS AND CALIBRATED SPRINGS SO THAT WHEN THE TEST PAVEMENT IS LOADED, A YIELDING SUPPORT, SIMULATING A SUBGRADE, IS PROVIDED. THE UNIT PRESSURES TRANSMITTED BY THE LOADING SYSTEM THROUGH THE TEST SPECIMEN ARE RECORDED BY DEFLECTION MEASURING BARS. CALIBRATION OF THE SUBGRADE INDICATED THAT PAVEMENT DEFLECTIONS CAN BE READ TO PLUS OR MINUS 0.003 INCH ACCURACY AND THAT THE SPRINGS AVAILABLE WITH THE EQUIPMENT HAVE SUBGRADE MODULI OF 22, 62, 87, 155, AND 325 PCI.

Descriptors :   *PAVEMENTS, DEFLECTION, MEASUREMENT, PRESSURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE