Asphalt In-Place Density (Percent of Gmm) Calculator

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Bulk Specific Gravity of the Core (Gmb)

The compacted core's bulk specific gravity, straight off the lab report.

Gmb describes the core as it came out of the road — asphalt, aggregate and the trapped air between them. It is the only one of the two numbers that knows anything about how hard the mat was rolled, which is why the ratio between them is a compaction measurement rather than a mix design one.

Theoretical Maximum Specific Gravity (Gmm)

The mix's void-free maximum specific gravity, sometimes called the Rice gravity.

Gmm is what the same mix would weigh per unit volume with every air void removed. It belongs to the mix design and the day's production, not to the core, so a Gmm taken from a different mix or a different day makes the ratio meaningless however carefully the core was tested.

Specified Minimum Density (Percent of Gmm)

The acceptance threshold the specification sets for this lift.

Agency specifications set this figure, and it moves between authorities, between mix types and between mainline and longitudinal-joint locations. Enter the one written into your project's specification rather than a remembered figure — the whole point of the comparison is that it is the contract's number, not a general one.

In-place density

93.73 %

High confidence

Air void content: 6.27 %
Margin over the specified minimum: 1.73 %
Specified minimum applied: 92 %

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

Percent of Gmm = Gmb ÷ Gmm × 100, and air voids = 100 − percent of Gmm. Both follow from the definitions of the two gravities; no coefficient is involved.
AASHTO T 166, Bulk Specific Gravity (Gmb) of Compacted Asphalt Mixtures Using Saturated Surface-Dry Specimens — the test the core's Gmb comes from
AASHTO T 209, Theoretical Maximum Specific Gravity and Density of Asphalt Mixtures (Gmm) — the test the mix's Gmm comes from

Inputs used

Bulk Specific Gravity of the Core (Gmb): 2.35
Theoretical Maximum Specific Gravity (Gmm): 2.5
Specified Minimum Density (Percent of Gmm): 92

Intermediate steps

Air void content: 6.27 %
Margin over the specified minimum: 1.73 %
Specified minimum applied: 92 %

Final result93.73 %

What this calculation does not cover

One core describes one location. Acceptance is normally decided on a lot with several cores, by the specification's own statistical method.
Nothing here judges whether the Gmm used belongs to the same mix and production day as the core.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-30 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations3

Percent of Gmm = Gmb ÷ Gmm × 100, and air voids = 100 − percent of Gmm. Both follow from the definitions of the two gravities; no coefficient is involved.
AASHTO T 166, Bulk Specific Gravity (Gmb) of Compacted Asphalt Mixtures Using Saturated Surface-Dry Specimens — the test the core's Gmb comes from
AASHTO T 209, Theoretical Maximum Specific Gravity and Density of Asphalt Mixtures (Gmm) — the test the mix's Gmm comes from

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Overlaying an Asphalt Surfaceuses this calculator

An overlay adds thickness to a surface that already has levels in it. What the old mat allows, what the ironwork costs, and how cores settle it.

How to calculate asphalt in-place density (percent of Gmm) in 4 steps

Bulk Specific Gravity of the Core (Gmb)The compacted core's bulk specific gravity, straight off the lab report.

Theoretical Maximum Specific Gravity (Gmm)The mix's void-free maximum specific gravity, sometimes called the Rice gravity.

Specified Minimum Density (Percent of Gmm)The acceptance threshold the specification sets for this lift.

In-place densityThe tool computes the in-place density from those figures and shows the formula, its sources, and a confidence rating alongside it.

Frequently asked questions

Why is air void content just 100 minus the density percentage?

Because the two gravities describe the same material with and without its air. Gmm is the void-free case, so whatever fraction of Gmm the core failed to reach is exactly the fraction of its volume that is air. The subtraction is a definition, not an approximation.

What happens to a pavement that finishes a couple of points low?

Air voids let water and oxygen through the mat, and both age the binder faster than traffic does. A lift left several points below its target typically shows early raveling and moisture damage, and the loss of service life is disproportionate to how small the density shortfall looks on paper.

Can I use a nuclear or non-nuclear gauge reading instead of a core?

Gauges are correlated back to cores rather than replacing them, and the correlation is mix-specific and drifts. Enter a gauge-derived Gmb only if the gauge has been calibrated against cores from this mix, and treat the answer as a process-control number rather than an acceptance one.

Does this apply to the longitudinal joint as well as the mat?

The arithmetic does, but the acceptance threshold usually does not. Many specifications allow the joint a lower minimum than the mat because it is compacted from one side only, so enter whichever figure the specification sets for the location the core came from.