Asphalt Mix Types — HMA, WMA, SMA, Cold Mix, Porous and RAP
Every asphalt mix is aggregate plus bitumen. What separates them is gradation, binder content and production temperature. This guide covers all seven mix families with densities, costs and applications, plus the French, Indian, UK and Pakistani regional designations.
The main mix families
Every asphalt mix is aggregate plus bitumen binder. What distinguishes them is the aggregate gradation, the binder content and grade, and the temperature at which they are produced. Those three choices determine density, void content, cost, workability and what the material is good for.
| Mix type | lb/ft³ | kg/m³ | t/m³ | Air voids | Typical use | Standard |
|---|---|---|---|---|---|---|
| Dense-graded HMA | 145 | 2,322.7 | 2.32 | 3–5% | Standard surface and binder courses for driveways, lots and roads | AASHTO M 323 / Superpave |
| Stone Matrix Asphalt (SMA) | 150 | 2,402.8 | 2.40 | 3–4% | High-traffic highways, rut-resistant surface course | AASHTO M 325 / EN 13108-5 |
| Warm Mix Asphalt (WMA) | 143 | 2,290.7 | 2.29 | 4–6% | Same uses as HMA, produced 30–100 °F cooler | AASHTO M 323 (WMA appendix) |
| Open-Graded Friction Course | 115 | 1,841.8 | 1.84 | 15–22% | Thin porous wearing course for spray and noise reduction | AASHTO M 323 / NAPA IS-115 |
| Porous / Permeable Asphalt | 100 | 1,601.8 | 1.60 | 18–25% | Full-depth permeable pavement, stormwater infiltration lots | NAPA IS-131 |
| Cold Mix Asphalt | 140 | 2,242.6 | 2.24 | 6–10% | Pothole patching, temporary repairs, low-traffic rural surfacing | ASTM D4215 |
| RAP Millings (recycled) | 125 | 2,002.3 | 2.00 | 8–14% | Driveways, base layers, rural roads, temporary access | AASHTO M 323 §RAP |
| Dense Bituminous Macadam (DBM) | 148 | 2,370.8 | 2.37 | 3–6% | Binder / base course in India and South Asia | MoRTH Clause 507 |
| Bituminous Concrete (BC) | 147 | 2,354.7 | 2.35 | 3–5% | Surface course in India (MoRTH), equivalent to dense HMA | MoRTH Clause 509 |
| Bituminous Macadam (BM) | 135 | 2,162.5 | 2.16 | 5–10% | Open-graded base / profile-correcting course, India | MoRTH Clause 504 |
| BBSG 0/10 (Béton Bitumineux Semi-Grenu) | 148 | 2,370.8 | 2.37 | 5–8% | Couche de roulement standard en France, 5–7 cm | NF EN 13108-1 / NF P 98-130 |
| BBME (Béton Bitumineux à Module Élevé) | 150 | 2,402.8 | 2.40 | 4–6% | Couche de roulement à fort trafic, liant modifié | NF EN 13108-1 / NF P 98-141 |
| Grave Bitume (GB3/GB4) | 149 | 2,386.8 | 2.39 | 4–7% | Couche d'assise / de base, France | NF EN 13108-1 / NF P 98-138 |
| EME 2 (Enrobé à Module Élevé) | 152 | 2,434.8 | 2.43 | 2–5% | Couche de base à très fort trafic, épaisseur réduite | NF EN 13108-1 / NF P 98-140 |
| Hot Rolled Asphalt (HRA) | 143 | 2,290.7 | 2.29 | 3–6% | Traditional UK surface course with pre-coated chippings | BS EN 13108-4 / BS 594987 |
| Bitumen binder (PG 64-22 / 60-70 pen) | 65 | 1,041.2 | 1.04 | — | Liquid binder only — tack coat, prime coat, seal coat | AASHTO M 320 / EN 12591 |
Comparison table
| HMA | WMA | Cold mix | SMA | OGFC | Porous | |
|---|---|---|---|---|---|---|
| Production temp | 275–350 °F | 215–275 °F | Ambient | 290–350 °F | 275–330 °F | 275–330 °F |
| Density (lb/ft³) | 145 | 143 | 140 | 150 | 115 | 100 |
| Air voids | 3–5% | 4–6% | 6–10% | 3–4% | 15–22% | 18–25% |
| Binder content | 4.5–6% | 4.5–6% | 4–6% | 6–7% | 6% | 6.5% |
| Relative cost | baseline | +0–5% | +10% | +40% | +20% | +30% |
| Rut resistance | Good | Good | Poor | Excellent | Fair | Fair |
| Permeability | Very low | Very low | Moderate | Very low | High | Very high |
| Typical use | All paving | All paving | Patching | High-traffic surface | Thin friction course | Stormwater pavement |
Hot mix asphalt (HMA)
The default. Aggregate and binder combined at 275–350 °F, hauled hot, placed by a paver and compacted before it cools below about 185 °F. Dense-graded HMA is what almost every price quotation and every generic asphalt calculator refers to.
Within HMA, mixes are designated by nominal maximum aggregate size — 9.5 mm, 12.5 mm, 19 mm, 25 mm — which determines both where the mix goes in the structure and how thick a lift can be placed. A 12.5 mm surface mix goes down at 1.5–2 inches; a 25 mm base mix at 3–4 inches.
Strengths: proven, universally available, cheapest per ton of the fresh
mixes, wide range of gradations.
Limitations: temperature-sensitive logistics, seasonal, high plant energy
use.
Warm mix asphalt (WMA)
The same materials produced 30–100 °F cooler, using one of three approaches: chemical additives that reduce binder viscosity, foaming with a small quantity of water injected into the binder, or organic waxes that melt at production temperature and stiffen on cooling.
Strengths: 15–30% less plant fuel, substantially less fume exposure for
crews, longer haul distances, paving season extended by two to four weeks at each end, and
easier compaction of thin lifts in cool weather.
Limitations: some early moisture-susceptibility concerns, largely addressed by
anti-strip additives; slightly lower density.
WMA now accounts for a large share of US tonnage and is priced at or near HMA parity.
Cold mix asphalt
Aggregate coated with bitumen emulsion or cutback binder at ambient temperature. Because it does not need heat, it can be stockpiled for months and placed by hand from a bucket.
Strengths: stockpilable, year-round, no plant required at the point of use,
ideal for emergency and remote repairs.
Limitations: lower strength, slower to gain final properties as the emulsion
breaks and water evaporates, and not a permanent pavement in its own right.
Cold mix is a repair material. Bagged cold patch for potholes costs $180–$350 per ton, which looks alarming until you remember you are buying 25 kg at a time.
Stone matrix asphalt (SMA)
Gap-graded, so that coarse aggregate particles bear directly on one another rather than floating in a matrix of fines. That stone-on-stone skeleton is what gives SMA its rutting resistance. The gaps are filled with a rich mastic of binder, filler and cellulose fibre — the fibre is there to stop the binder draining out of the mix during transport.
Strengths: outstanding rut resistance, excellent durability, good surface
texture and noise characteristics.
Limitations: 25–50% more expensive per ton, requires careful mix design and
experienced placement, and the fibre adds a handling step at the plant.
Standard on European motorway surfaces and increasingly common on US interstate resurfacing and heavy intersections.
Open-graded and porous asphalt
Two related materials with different purposes.
Open-graded friction course (OGFC / PFC)
A thin porous wearing course, typically ¾ to 1.5 inches, laid over an impermeable structure. Water drains laterally within the layer to the edge rather than sheeting across the surface. Cuts spray behind vehicles, reduces hydroplaning risk and lowers tyre noise by 3–5 dB.
Full-depth porous asphalt
A stormwater management system. Water passes through the entire pavement into an open-graded stone reservoir beneath, then infiltrates into the subgrade. Used on parking lots where stormwater detention would otherwise consume developable land.
Both: far lighter than dense mix at 100–115 lb/ft³, more expensive per ton, and requiring maintenance — vacuum sweeping to keep the voids open.
Recycled asphalt (RAP)
Milled pavement, either used as-is or blended back into new mix. Asphalt is the most recycled material in North America by tonnage, and the great majority of milled pavement goes back into new production rather than to landfill.
| Use | RAP content | Notes |
|---|---|---|
| Standalone millings surfacing | 100% | Driveways, yards, trails; density 125 lb/ft³ |
| Base layer under new asphalt | 100% | Stiffer than crushed stone, cheaper |
| Surface course blend | 15–25% | Capped to protect surface texture and binder properties |
| Binder course blend | 25–40% | |
| Base course blend | 30–50% | Highest permitted percentages |
| Cold in-place recycling | 100% | Existing pavement recycled on site with emulsion or foam |
| Full-depth reclamation | 100% | Pavement and base pulverised and stabilised together |
See the millings calculator, which uses the correct RAP density.
Regional designations
France
| Designation | Full name | Layer | Density |
|---|---|---|---|
| BBSG | Béton bitumineux semi-grenu | Couche de roulement, 5–7 cm | 2,370 kg/m³ |
| BBME | Béton bitumineux à module élevé | Couche de roulement, fort trafic | 2,400 kg/m³ |
| BBTM | Béton bitumineux très mince | Couche de roulement mince, 2–3 cm | 2,300 kg/m³ |
| GB (GB2–GB4) | Grave bitume | Couche d'assise | 2,385 kg/m³ |
| EME 2 | Enrobé à module élevé | Couche de base, fort trafic | 2,435 kg/m³ |
| GNT | Grave non traitée | Couche de fondation (non liée) | 2,100 kg/m³ |
India (MoRTH)
| Designation | Clause | Layer | Density |
|---|---|---|---|
| BC — Bituminous Concrete | 509 | Wearing course, 30–50 mm | 2,355 kg/m³ |
| DBM — Dense Bituminous Macadam | 507 | Binder / base course, 50–100 mm | 2,370 kg/m³ |
| BM — Bituminous Macadam | 504 | Base course, open-graded | 2,160 kg/m³ |
| SDBC — Semi-Dense Bituminous Concrete | 508 | Thin wearing course, 25–30 mm | 2,330 kg/m³ |
| Premix carpet | 511 | Thin surfacing, 20 mm | ~2,000 kg/m³ |
| WMM — Wet Mix Macadam | 406 | Granular base (unbound) | 2,200 kg/m³ |
United Kingdom
| Designation | Standard | Layer | Notes |
|---|---|---|---|
| AC surf (asphalt concrete) | BS EN 13108-1 | Surface course | The modern default |
| HRA — hot rolled asphalt | BS EN 13108-4 | Surface course | Traditional, with pre-coated chippings |
| SMA | BS EN 13108-5 | Surface course | High-traffic routes |
| Thin surface course systems | BS EN 13108-2 | Surface course, 20–40 mm | Proprietary products |
| AC bin / AC base | BS EN 13108-1 | Binder and base courses | |
| Type 1 sub-base | SHW Clause 803 | Unbound sub-base |
Pakistan (NHA)
Asphaltic concrete wearing and base courses to NHA General Specifications, with binder specified by penetration grade — 60/70 across most of the country, 80/100 in the colder northern regions. Marshall mix design remains the standard method.
Choosing a mix
| Situation | Recommended mix | Why |
|---|---|---|
| Residential driveway | Dense-graded HMA, 9.5 or 12.5 mm | Cheapest fresh mix, smooth finish, proven |
| Budget rural driveway | RAP millings | 80–90% cheaper, acceptable finish |
| Commercial parking lot | Dense HMA, two lifts | Structural capacity at reasonable cost |
| Truck route or loading dock | SMA or heavy dense HMA | Rut resistance under slow heavy loads |
| Highway surface, high traffic | SMA or PMB dense HMA | Rut and fatigue resistance |
| Spray and noise reduction | OGFC / PFC | Porous surface drains laterally |
| Stormwater management lot | Full-depth porous | Infiltrates rather than sheds |
| Pothole repair, winter | Cold mix | Only option below paving temperature |
| Long haul from plant | WMA | Wider temperature window |
| Cool-weather paving | WMA | Extended season |
Frequently asked questions
What are the different types of asphalt?
The main families are hot mix (HMA), warm mix (WMA), cold mix, stone matrix asphalt (SMA), open-graded friction course, porous asphalt and recycled RAP. Regional designations layer on top: BBSG, BBME, GB and EME in France; BC, DBM and BM in India; hot rolled asphalt and thin surface course systems in the UK.
What is the difference between HMA and SMA?
HMA is dense-graded with a continuous aggregate gradation. SMA is gap-graded with stone-on-stone contact, higher binder content and cellulose fibre to stop the binder draining. SMA costs 25–50% more per ton and resists rutting far better, which is why it is standard on heavily trafficked highway surfaces.
What is BBSG?
Béton bitumineux semi-grenu — the standard French dense-graded surface course, usually a 0/10 gradation laid 5–7 cm thick at about 2,370 kg/m³. It is roughly equivalent to a US 12.5 mm Superpave surface mix.
What is DBM in road construction?
Dense Bituminous Macadam, specified under MoRTH Clause 507 in India. It is the binder and base course layer, denser and coarser than the Bituminous Concrete surface above it, at around 2,370 kg/m³.
What is premix carpet?
An Indian thin open-graded bituminous surfacing, typically 20 mm thick, used on low-volume rural roads and usually finished with a seal coat. It is considerably lighter than dense mixes.
Which asphalt mix is best for a driveway?
Standard dense-graded hot mix. Specialist mixes solve problems a driveway does not have. The only real alternative worth considering is RAP millings if budget dominates and finish quality does not.
What is warm mix asphalt and is it as good as hot mix?
WMA is produced 30–100 °F cooler using additives, foaming or organic waxes. Field performance is broadly equivalent to HMA, and it uses 15–30% less plant fuel, produces less fume and allows longer hauls and a slightly extended paving season.
What is the difference between tarmac and asphalt?
None, in practice. "Tarmac" is a British colloquialism derived from tarmacadam, an early bitumen-bound macadam. Modern UK surfacing is asphalt concrete to BS EN 13108, the same material family used everywhere else.
Sources and further reading
- NAPA — National Asphalt Pavement Association
- AASHTO
- EAPA — European Asphalt Pavement Association
- ASTM International
- MoRTH — Ministry of Road Transport & Highways, India
- BSI — BS 594987
- AFNOR — normes NF EN 13108
Related calculators and guides
Density guide
Density for every mix listed here.
Road layers
Which mix goes in which layer.