Abstract:
THE WASHINGTON METHOD IS AN ADAPTATION OF THE PRESSURE PRINCIPLE IN A MANNER WHICH DIFFERS FROM THAT COMMONLY EMPLOYED. A CHAMBER CONTAINING AIR IS CONNECTED THROUGH A VALVE TO A SAMPLE OF CONCRETE IN A SEALED CONTAINER. WITH THE VALVE CLOSED, AIR IS FORCED INTO THE CHAMBER TO A MEASURED GAGE PRESSURE. WHEN THE CONNECTING VALVE IS OPENED, THE GAGE PRESSURE ON THE SYSTEM DROPS TO A VALUE DEPENDENT ON THE AIR CONTENT OF THE CONCRETE. ADVANTAGES OF THE METHOD ARE: (1) IN COMMON WITH OTHER PRESSURE METHODS, NO WEIGHT DETERMINATIONS ARE NEEDED AND THE PERCENTAGE OF AIR IN THE SAMPLE CAN BE READ DIRECTLY. (2) COMPARED TO OTHER PRESSURE METHODS, THE APPARATUS IS MORE COMPACT, DETERMINATIONS ARE MADE MORE RAPIDLY, NO WATER IS USED IN THE TEST, CORRECTIONS ARE NOT NEEDED UNDER VARYING BAROMETRIC PRESSURES, AND CALIBRATIONS CAN BE MADE READILY IN THE FIELD OVER THE FULL USABLE RANGE OF AIR CONTENTS. CONSTRUCTION OF THE DEVICE AND AUXILIARY APPARATUS IS ILLUSTRATED. /AUTHOR/
Supplemental Notes:
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