NCBC Davisville, R.I., 1981--II "It goes in where....?"

The characteristics of a finished asphalt mix are determined by the specifications of the ingredients. There are only two basic ingredients; crushed stone which varies in size from a couple of inches across down to grains of sand, and hot liquid asphalt as a "binder" to hold all the stone particles together. A mix specification is determined according to the type of service the pavement is to perform, the local climate, soil conditions, and material availability. For example, aircraft landing strip mix is a liitle different from vehicle parking lot mix or hasty temporary roadway mix, etc. Whether the climate is predominently hot or cold affects the choice of liquid asphalt grade. Several different mix types can be applied in successive layers of varying depths to achieve desired final results. Each layer is called a "lift" and the combined lifts form the complete asphalt paving "mat"

The screening unit of the plant separates the crushed stone into several sizes which are then recombined by the mixing process within the plant into the exact proportions required for each mix. The different sizes of stone are weighed to verify proper proportioning before being transferred to the pugmill to complete the process. After weighing, the recombined stone mix flows from the bottom of the weigh box into the hot elevator which lifts it up into the pugmill mixing chamber for the final step of production.

--Normand Dupuis EOC USNR-(Ret.)

Crushed stone separated into coarse and fine sizes by the screens above, is re-combined here into specific mix proportions.	NCBC truck crane lifts the weigh box unit so that pre-built wooden cribbing can be placed under support legs for required ground clearance.
Up and ready for next piece. Wooden cribbing is plainly visible under support legs of weigh box. Small bins under hoppers are used to take material samples for testing.	"Topping out ". Seabees swarm around screen unit being lowered on top of weigh box bin section.
Equipment Operator Second Class Gregory Parmes of MD, and Equipment Operator Second Class Normand Dupuis of VA., release shipping locks to allow screens to move as intended during operation	Supervisor Dan McCarthy directs the placement of another piece of "Jigsaw Puzzle", the cold elevator which will carry stone from the supply bins into the drier unit.

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