HMA Base Types C and D should be maintained within which temperature range?

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Multiple Choice

HMA Base Types C and D should be maintained within which temperature range?

Explanation:
Maintaining HMA base types C and D at a mat temperature of 240°F to 275°F keeps the mix workable enough for proper compaction while preventing excessive softening. Base mixes have lower binder content and different stiffness, so they need to stay cooler than surface mixes to densify correctly without bleeding or rutting. Within this range, the binder viscosity is just right to coat aggregates and permit rolling to achieve the desired density and low air voids. If the mat gets hotter, you risk drainage and instability; if it’s cooler, compaction becomes difficult and density suffers. The other ranges push toward too hot or too cold for base layers, making 240°F to 275°F the appropriate maintained window.

Maintaining HMA base types C and D at a mat temperature of 240°F to 275°F keeps the mix workable enough for proper compaction while preventing excessive softening. Base mixes have lower binder content and different stiffness, so they need to stay cooler than surface mixes to densify correctly without bleeding or rutting. Within this range, the binder viscosity is just right to coat aggregates and permit rolling to achieve the desired density and low air voids. If the mat gets hotter, you risk drainage and instability; if it’s cooler, compaction becomes difficult and density suffers. The other ranges push toward too hot or too cold for base layers, making 240°F to 275°F the appropriate maintained window.

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