What is asphalt pavingin construction?

Tons = sy x lift inches x 110 / 2,000. The worked parking lot example runs it end to end: 5,000 sy at a 2.5 inch base lift is 5,000 x 2.5 x 110 / 2,000 = 687.5 tons, and the 1.5 inch surface lift adds 412.5 tons, so the lot paves out at 1,100 tons across both lifts.

Using the common rule of thumb of about 110 pounds per square yard per inch of thickness, one sy at 3 inches weighs about 330 lbs, or 0.165 tons. Flipped around, one ton covers roughly 6 sy at 3 inches thick. Actual coverage shifts with the mix design and compacted density, so paving contractors check the rule against the plant's mix-specific conversion before committing tonnage.

Base course (often called binder) uses larger aggregate and goes down first in a thicker lift to carry structural load. Surface course, the wearing lift, uses finer aggregate for a tight, smooth, water-resistant finish and goes down last, often after curbs and utilities are complete. They are separate mix designs at separate prices, placed in separate passes with a tack coat between them, so estimators take them off as separate lines.

The plant batches, sells, and trucks hot mix by the ton, and tonnage captures thickness in a way area cannot: 2 inches and 4 inches over the same square footage are very different costs. Per-ton pricing also lets bids carry an asphalt cement adjustment when the liquid asphalt index moves. Square foot pricing shows up mostly in early budgets, then gets converted to tons for the real bid.