THE MECHANICAL SUBGRADE A PAVEMENT LOAD, TRANSMISSION TESTING DEVICE
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 18, 1960
- Accession Number
- AD0250648
Entities
People
- R.j. Lowe
Organizations
- Naval Facilities Engineering Service Center