Which statement about VMA calculation is true?

• A. VMA is defined as those inter-angular spaces between aggregate particles within a compacted specimen which contain either air or asphalt ( but not both ).
• B. VMA is the volume of voids in the mineral aggregate that can contain asphalt.
• C. VMA is calculated using the bulk specific gravity of the combined aggregates.
• D. VMA represents the total void area in the asphalt mixture.

Answer: (C)

VMA is the portion of volume in the mineral aggregate that must be available to bind and coat the aggregates with asphalt. To calculate it, you rely on gravimetric properties of the mix: the maximum theoretical specific gravity of the asphalt mixture (Gmm) and the bulk specific gravity of the aggregate (Gsb), which together describe how much space the aggregate structure provides for asphalt.

In practice, VMA is found from the difference between Gmm and Gsb, expressed as a percentage: VMA = [(Gmm − Gsb) / Gmm] × 100. This shows how much of the mix’s volume is voids in the mineral aggregate that asphalt must fill, reflecting the aggregate skeleton’s capacity to hold binder.

That’s why the statement saying VMA is calculated using the bulk specific gravity of the combined aggregates is the best description: it emphasizes the gravimetric basis used to determine how much space is available for asphalt within the aggregate structure. The other options describe related ideas about voids but do not capture the specific calculation method involving the aggregate’s bulk gravity and the mixture’s maximum specific gravity.