Aggregate
The sand, gravel and crushed stone that make up most of concrete and every base course.
Quick Answer
Aggregate is granular material, such as sand, gravel and crushed stone, used in concrete, asphalt, backfill and base courses. Fine aggregate is sand-sized and coarse aggregate is stone-sized. Estimators take it off by volume (CY) or weight (tons), and the conversion between the two is a frequent pricing error.
The Full Picture
Aggregate does two jobs on a project. Inside concrete and asphalt it is the bulk filler that gives volume and strength. Outside them it is a construction material in its own right: base course under slabs and paving, drainage stone around pipe and footing drains, bedding for utilities, and structural fill. The Portland Cement Association notes that aggregates make up 60% to 75% of the total volume of concrete, so the material is mostly aggregate with cement paste binding it.
Aggregate is divided into fine (sand) and coarse (gravel or crushed stone), and it is specified by gradation, the mix of particle sizes, and by quality tests. For a concrete mix the structural engineer or mix design sets the maximum coarse size, which depends on member thickness and reinforcement spacing. Base and fill materials are named in the civil specs, typically by a state DOT gradation or a project-specific class. Specified compaction is carried in the earthwork or paving section, normally Division 31 or Division 32.
In takeoff the base quantity is volume. Length x width x depth of a layer gives cubic feet, divided by 27 for CY. Material is often bought by the ton, so the estimator converts with a unit weight from the supplier, which changes with stone type, moisture and gradation. The trap is the difference between compacted volume, which is what the drawings show, and loose volume, which is what is delivered. Extra material is also needed for overbuild, trench widening, thickness tolerance and compaction, and that allowance varies by job.
Pricing mistakes tend to be about delivery and basis. Trucking can dominate the cost of low-value aggregate, so haul distance, truck capacity and minimum loads need to be in the number. The estimator also needs to be clear about whether a quote includes placement and compaction, or only delivery to site. Aggregate sourcing is regional, so unit costs from a past project in another market are unreliable, and USGS publishes national crushed stone production and price statistics.
Real Examples
Common Misconceptions
People assume: Aggregate is just fill, so the quantity doesn't need care.
Actually: Compacted volume on the drawings, loose volume delivered, and weight billed by the ton are three different numbers. Mixing them up is a common source of over- or under-buying.
People assume: Aggregate and concrete are interchangeable terms.
Actually: Aggregate is one ingredient of concrete. Aggregates are 60% to 75% of the volume, with cement and water making up the rest of the mix.
Does MeltPlan Solve This?
Partially — adjacentAggregate base, stone envelopes and fill show up on civil and site plans as areas, lengths and depths that have to be measured. MeltPlan's takeoff service has AI pull quantities from plans and US-based experienced estimators review and adjust them. Unit weights, haul and supplier pricing are still set by your estimator.
Get base and fill volumes measured from your plans →Frequently Asked Questions
How is aggregate measured in a takeoff?
By volume in cubic yards, from plan area times layer depth, or by weight in tons when the supplier sells that way. Linear items like drainage stone runs are measured by length and cross section.
What is the difference between fine and coarse aggregate?
Fine aggregate is sand-sized and coarse aggregate is gravel or crushed stone. Mix designs and specs set the allowed sizes and gradations for each use.
How do you convert cubic yards of aggregate to tons?
Multiply CY by the material's unit weight in tons per CY, taken from the supplier. It varies with stone type, gradation and moisture, so it should not be guessed.
Why does aggregate take more than the plan quantity?
Loose material is compacted in place, and layers rarely come out at exactly the specified thickness, so estimators add an allowance for compaction, overbuild and trench width. The size depends on the material and job.