ROAD MATERIAL TESTS.
In the Road Material Tests the machines used are mainly those
devised by Dr. Logan Waller Page, director of the United States
office of public roads. For measuring the strength of the stone cylindrical
samples are cut out with a diamond drill and tested under impact
and in the 40,000-pound compression machine. The resistance
to abrasion is measured on fragments of the stone, rotated in heavy
cast iron cylinders mounted on their diagonals. The binding power
of the dust is measured by impact tests on cylindrical briquettes
formed under heavy hydraulic pressure. The dust for these briquettes
is produced in a ball mill fed with fine stone broken in a
small crusher. This part of the testing outfit has been installed
largely by the generous aid of Dr. Page. Useful experimental researches
on the road-building rocks and gravels of Virginia are carried
out with it each year.
