Highway Materials Engineering, Superpave Gyratory Compaction & Asphalt Pavement QA
Hot-Mix Asphalt Air Voids (Va), VMA & VFA Formula
Calculate Compacted Specimen Air Voids V_a (%), Voids in Mineral Aggregate VMA (%), Voids Filled with Asphalt VFA (%), and Superpave Volumetric Acceptance Status.
Below 3% Air Voids hot-mix asphalt bleeds and ruts under summer truck tires—above 7% it oxidizes and ravel-cracks!
Superpave gyratory compactor (N_design) highway pavement quality control hinges on three coupled volumetric ratios derived from Compacted Bulk Specific Gravity G_mb, Rice Maximum Theoretical Loose Specific Gravity G_mm, Combined Aggregate Bulk Specific Gravity G_sb, and Total Asphalt Binder Weight Percentage P_b% (so Stone Percentage P_s = 100 - P_b): (1) Percent Air Voids V_a = ((G_mm - G_mb) / G_mm) * 100 (design target 4.0%, strictly [3.0%, 5.0%]); (2) Voids in the Mineral Aggregate VMA = 100 - ((G_mb * (100 - P_b)) / G_sb) (intergranular space housing BOTH effective asphalt film and air pockets, >= 14.0% for 12.5 mm nominal maximum aggregate size); and (3) Voids Filled with Asphalt VFA = ((VMA - V_a) / VMA) * 100 (held in [65%, 75%] to prevent plastic flushing/rutting)!
Verify on a 12.5 mm Surface-Course Superpave Plant Core—Compacted_Bulk_SG G_mb = 2.380 (B2), Max_Theoretical_Rice_SG G_mm = 2.480 (B3), Aggregate_Bulk_SG G_sb = 2.660 (B4), and Binder_Content P_b = 5.30% (B5): Air Voids V_a land right on target at 4.03% (E2), Voids in Mineral Aggregate VMA reach 15.27% (>= 14.0%!, E3), Voids Filled with Asphalt VFA hit 73.59% (inside [65%, 75%]!, E4), and Lab QA Status confirms "SUPERPAVE SPEC PASS" (E5)!
| Superpave HMA Volumetric KPI (Gmb=2.380, Gmm=2.480, Gsb=2.660, Pb=5.3%) | Formula | Verified Output |
|---|---|---|
| Compacted Air Voids Va (%) | ((Gmm - Gmb) / Gmm) * 100 | 4.03% (1.61% @ Gmb=2.440 flushing!) |
| Voids in Mineral Agg VMA (%) | 100 - ((Gmb * (100 - Pb)) / Gsb) | 15.27% (13.13% @ Gmb=2.440 crushed!) |
| Voids Filled w/ Asphalt VFA (%) | ((VMA - Va) / VMA) * 100 | 73.59% (87.72% @ Gmb=2.440 rutting!) |
| 12.5 mm Superpave Spec Gate | Va in [3,5] & VMA>=14 & VFA in [65,75] | SUPERPAVE SPEC PASS |
AASHTO R 35 Superpave Air Voids, VMA & VFA Volumetric Gate Formula
Validate 1.8 <= G_mb < G_mm <= 3.0, G_sb > 2.0, and Binder_Content P_b in [2.5%, 10.0%]!
=LET(gm_b, B2, gm_m, B3, gs_b, B4, pb_p, B5, IF(OR(gm_b < 1.8, gm_m <= gm_b, gm_m > 3, gs_b <= 2, pb_p < 2.5, pb_p > 10), "Invalid HMA Gravity Input", LET(va_p, ((gm_m - gm_b) / gm_m) * 100, vm_a, 100 - ((gm_b * (100 - pb_p)) / gs_b), IF(vm_a <= va_p, "Invalid HMA Gravity Input", LET(vf_a, ((vm_a - va_p) / vm_a) * 100, IF(AND(va_p >= 3, va_p <= 5, vm_a >= 14, vf_a >= 65, vf_a <= 75), "SUPERPAVE SPEC PASS", "OUT OF VOLUMETRIC SPEC"))))))Collapsed Aggregate Gradation Flushing & Rutting Failure Check (Set G_mb = 2.440)
Simulate excess baghouse fines collapsing the stone skeleton to G_mb B2 = 2.440: Air Voids E2 choke down to 1.61% (< 3%!), VMA E3 collapses to 13.13% (< 14%!), and VFA E4 spikes to 87.72%—triggering "OUT OF VOLUMETRIC SPEC" in E5 before highway wheel-path rutting occurs!
=IF(ISTEXT(E2), E2, LET(va_p, ((B3 - B2) / B3) * 100, vm_a, 100 - ((B2 * (100 - B5)) / B4), ROUND(((vm_a - va_p) / vm_a) * 100, 2)))Try the example
Use the original values or change them to test your understanding.