Lesson 6/Learning Event 4
TABLE 13. SCREEN SIZES
Step 3. Determine the Dryer Capacity.
The dryer capacity is controlled by the amount of moisture that must be removed from the
aggregate. Experienced engineers who become familiar with aggregates in an area can judge
moisture content by field examination. The best method and most accurate method uses an oven
with temperature control. The apparatuses used in the testing are usually found in the plant
laboratory so the testing done is under controlled conditions. This determination of the moisture
content can be best described in the following formula:
When the aggregate moisture content has been determined, the dryer capacity is obtained from
the Dryer Capacity Chart (Table 14 or Figure 22).
-Example: From Table 14 and Figure 22, dryer capacity equals 138 TPH at 6% moisture
NOTE: Dried aggregates may contain no more than 0.5% moisture when mixed with asphalt
cement in high type mixes.