Road construction
Road Base and Road Construction Supplies
We have the materials to make sure your roads and foundations are safe, durable, and cost-effective, including bases, subbases, crushed rock, and more. With bulk next-day delivery available, we can get your materials to site when you need them.
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Road construction supplies and materials for NSW civil projects
Hunter Blue Metal supplies road base and road construction materials for projects across the Hunter Valley, Newcastle and NSW. Our range includes TfNSW-specification (formerly RMS) DGB20 base course and DGS40 subbase, unspecified 20mm and 40mm road base, capping aggregate and 65mm minus fill, quarried at Merriwa in the Upper Hunter and delivered in bulk to site.
Whether you’re building a residential driveway, a commercial car park, or working on major civil infrastructure, our road construction materials deliver the strength, stability and compaction properties your project demands. Our team has decades of experience supplying TfNSW-specification road base alongside general-purpose options to suit any budget.
Road construction supplies at a glance
Compare the road construction materials we stock and match your road pavement layer to the right product:
| Product | Road layer | Specification | Typical use |
|---|---|---|---|
| DGB20 | Base course | TfNSW 3051 dense graded base (20mm) | Council roads, government projects, commercial pavements |
| DGS40 | Subbase | TfNSW 3051 dense graded subbase (40mm) | Load distribution beneath base course; drainage |
| 20mm unspec road base | Base course | No formal TfNSW certification | Driveways, private roads, lighter-traffic applications |
| 40mm unspec road base | Subbase | No formal TfNSW certification | Lower-cost subbase for private and non-spec projects |
| 65mm minus | Select fill / formation | Crushed rock fill | Select material zone (SMZ) beneath subbase, drainage fill |
| Capping aggregate | Capping layer | Sized for trackbed / pavement use | Rail and road formation capping |
Not sure which road base or subbase suits your project? Compare them side by side in Which road base do you need?, read our complete road construction supplies guide for NSW civil projects, or call our team on 1300 150 777 for a quote.
What Are Road Construction Base Materials?
Road construction base materials form the structural foundation beneath sealed road surfaces, driveways, and pavements. These crushed rock products are engineered to distribute loads, resist deformation, and provide a stable platform for asphalt or concrete surfaces.
A typical road construction profile consists of several layers. The subgrade is the natural ground or imported fill at the bottom. Above that sits the subbase layer (such as DGS40), a coarser material that provides drainage and load distribution. The base course (such as DGB20) sits on top as a finer, highly compacted layer directly beneath the wearing surface. Finally, the surface course of asphalt, concrete, or seal coat finishes the structure. Our guide to how aggregates are used in road construction walks through each layer in detail.
Each layer plays a critical role in road performance. Using the correct base materials ensures your road or pavement can handle traffic loads without cracking, rutting, or premature failure. For related aggregate products used in road construction, see our full range.
Why Quality Base Materials Matter
Substandard road base leads to costly problems including uneven surfaces and potholing, premature cracking and edge failure, poor drainage and water damage, and expensive repairs and resurfacing.
Investing in quality road construction base materials from the outset saves money over the life of your project and helps ensure compliance with engineering specifications.
Our Road Construction Products
Base Course (DGB20): 20mm minus
DGB20 is a TfNSW-specified dense graded base material designed for use as the primary load-bearing layer in road construction. This 20mm crushed rock product compacts to a dense, stable surface that resists deformation under traffic loads.
Applications: Sealed roads and highways, commercial driveways and car parks, council road construction, and heavy-traffic industrial yards.
Specifications: Manufactured to TfNSW specification 3051 for base course, with test certificates available on request. Maximum particle size of 20mm with controlled fines content for optimal compaction. Weighs approximately 2.2 to 2.4 tonnes per cubic metre compacted. Read our full DGB20 guide.
Subbase (DGS40): 40mm DGS
DGS40 is a dense graded subbase material specified for use beneath the base course layer. This coarser 40mm product provides excellent load distribution and drainage while reducing the volume of more expensive base course material required.
Applications: Subbase layer for roads and highways, foundation layer for heavy-duty pavements, bulk fill for car parks and hardstands, and rural road construction.
Specifications: Manufactured to TfNSW specification 3051 for subbase. 40mm maximum particle size with graded fines for compaction. Weighs approximately 2.1 to 2.3 tonnes per cubic metre compacted. Read our full DGS40 guide.
Subbase: 20mm unspec
A versatile 20mm subbase material suitable for projects where full TfNSW specification isn't required. This product offers excellent value for general road construction and driveway projects.
Applications: Residential driveways, farm access roads, private roads and laneways, and light-traffic car parks.
Specifications: 20mm crushed rock with graded particle sizes. Compacts well for stable, durable results.
Subbase: 40mm unspec
A cost-effective 40mm subbase option for general construction use. Ideal for projects requiring bulk material where certified TfNSW specification isn't mandatory.
Applications: Rural road base, property access tracks, laydown areas and hardstands, and general fill requiring load-bearing capacity.
Specifications: 40mm maximum particle size. Good compaction and drainage properties.
Select Fill / General Fill: 65mm minus
A versatile bulk fill material suitable for building up levels, filling voids, and creating stable foundations. This 65mm minus product provides economical volume with reasonable compaction characteristics.
Applications: Site levelling and bulk fill, road formation and embankments, backfill behind retaining walls, and general construction fill.
Specifications: 65mm maximum particle size with mixed fines. Suitable for compaction in lifts.
Road Construction Applications
Our road construction base materials support projects of all sizes across the Hunter Valley and NSW.
Residential projects benefit from our products for new home driveways, driveway extensions and widenings, garage and carport hardstands, and garden paths and walkways.
Commercial and industrial applications, including mining operations, include shopping centre car parks, warehouse and factory yards, service station forecourts, and office building access roads.
Civil and infrastructure works use our materials for council road construction and maintenance, subdivision road networks, rural road upgrades, and bridge approaches and culvert surrounds.
Rural and agricultural projects rely on our base materials for farm access roads and tracks, machinery shed hardstands, feedlot and dairy access areas, and property entrance upgrades.
For rail construction projects requiring similar base and capping materials, see our dedicated rail construction products.
Why Hunter Blue Metal?
Recognised as the Hunter Valley’s oversized rock specialists, Hunter Blue Metal supplies a comprehensive range of quarry products including aggregates, road base materials, rail construction products, specialty rock and sand and dust. Based in the Hunter region, we offer competitive pricing, responsive service and bulk next-day delivery across Newcastle, the Hunter Valley and surrounding areas. Our team has the expertise to recommend the right material for your project, and if we don’t stock it, we’ll source it for you.
Technical Information
Understanding Road Base Specifications
Transport for NSW (TfNSW, formerly RMS) specifications set the standard for road construction materials in NSW. Granular base and subbase are covered by TfNSW specification 3051. Products labelled DGB (Dense Graded Base) and DGS (Dense Graded Subbase) meet these specifications and are required for government road projects and many commercial developments.
Transport for New South Wales (TfNSW) outlines specific pavement design requirements to ensure a consistent approach in the construction of roadway infrastructure.
Common pavement design approaches include:
Full-depth asphalt: A 300mm Select Material Zone (SMZ) is laid atop the subgrade, with up to 350mm of asphalt placed on top of the SMZ.
Thick asphalt over cement sub-base: This method combines a layer of asphalt and a layer of cement stabilised material above the SMZ.
Sprayed seal over granular base: A granular sub-base is laid atop the SMZ before the application of Class One Granular Base.
Thick asphalt over lean-mix concrete: A layer of lean-mix concrete is placed above the SMZ, topped with an asphalt layer.
For fine materials used in pavement construction, see our crusher dust and manufactured sand products. For larger rock products used in drainage and erosion control alongside roads, see our specialty rock range.
Compaction and Grading
Particle size grading affects compaction and performance. Well-graded materials with a range of particle sizes compact more densely than single-sized products, creating stronger, more stable road bases.
Compaction requirements vary by layer. Base course such as DGB20 is typically compacted to 98 to 100 percent of maximum dry density, in lifts of no more than 150mm. Subbase such as DGS40 is typically compacted to 95 to 98 percent, in lifts of 150 to 200mm. Proper compaction is essential for achieving specified load-bearing capacity.
Moisture content during compaction affects results. Base materials should be compacted at optimum moisture content, typically slightly damp but not wet, for best density and stability.
How Much Road Base Do You Need?
Calculating road base quantities depends on your project area, required depth, and material type.
Typical total base depths:
| Application | Typical total base depth |
|---|---|
| Light residential driveways | 100 to 150mm |
| Standard driveways and car parks | 150 to 200mm |
| Commercial and heavy-traffic areas | 200 to 300mm or more |
Quantity calculation: Length (m) x Width (m) x Depth (m) = Volume (cubic metres). To convert to tonnes, multiply by the compacted density: approximately 2.2 to 2.4 tonnes per cubic metre for DGB20, and 2.1 to 2.3 for DGS40. Allow 10 to 15 percent extra for wastage and levelling.
Example: a 10m x 5m driveway base laid 150mm deep is 7.5 cubic metres, or roughly 16.5 to 18 tonnes of DGB20.
Need help with quantities?
Our team can recommend the right materials and calculate quantities for your project.
Related guides
Helpful explainers and buyer guides from our team:
- Which road base do you need? DGB20 vs DGS40 vs unspec
- DGB20 base course: TfNSW 3051 specification and supply
- DGS40 subbase: TfNSW 3051 specification and supply
- How aggregates are used in road construction: layer-by-layer guide
- Choosing road construction supplies: buyer's guide for NSW civil projects
- Crushed rock: types, sizes and bulk supply
Frequently Asked Questions
Base course (like DGB20) is the upper structural layer directly beneath the road surface. It uses finer material and requires higher compaction standards. Subbase (like DGS40) sits below the base course, using coarser material to provide load distribution and drainage. Most road construction projects require both layers.
For sealed driveways, we recommend DGB20 base course over a DGS40 subbase layer. For unsealed driveways, a quality 20mm road base compacted in layers provides a durable, all-weather surface.
Yes. Hunter Blue Metal offers bulk delivery of all road base and construction materials throughout the Hunter Valley and surrounding regions. Our fleet can deliver direct to your site, from single-truck loads for residential projects to multi-delivery schedules for major construction works.
DGS products meet TfNSW (formerly RMS) specifications and come with certification for use on government and specified commercial projects. Unspec materials are similar products without formal certification, ideal for private projects where specification compliance isn’t required.
The right material depends on your project type, expected traffic loads, and any specification requirements. Our team can recommend the best products for your needs. Get in touch with your project details.
Yes. Hunter Blue Metal supplies road base and subbase materials that meet Transport for NSW (TfNSW) specifications, including DGB20 base course and DGS40 subbase. These certified products are suitable for government road projects, council works and commercial developments requiring specification compliance. Contact our team for availability and documentation.
The required depth depends on your expected traffic loads and soil conditions. As a general guide, light residential driveways typically need 100-150mm total base depth, standard driveways and car parks require 150-200mm, and commercial or heavy-traffic areas need 200-300mm or more. Our team can recommend the appropriate depth and materials based on your specific project requirements.
Work out the compacted volume (length x width x depth in metres), then multiply by the material’s compacted density. DGB20 weighs approximately 2.2 to 2.4 tonnes per cubic metre compacted, and DGS40 approximately 2.1 to 2.3. For example, a 10m x 5m area laid 150mm deep is 7.5 cubic metres, or roughly 16.5 to 18 tonnes of DGB20. Allow 10 to 15 percent extra for wastage and levelling, or call 1300 150 777 and we’ll work it out for you.
Service Area
Road Construction Materials Delivered Across the Hunter Valley
Hunter Blue Metal supplies and delivers road construction base materials throughout the Hunter region and beyond. We service Muswellbrook, Singleton, and Upper Hunter areas as well as Maitland, Cessnock, and Lower Hunter. We also deliver to Newcastle and Lake Macquarie, the Central Coast, and regional NSW by arrangement.
Our bulk delivery fleet ensures your road base materials arrive on site when you need them, from single-truck loads for residential projects to multi-delivery schedules for major construction works. Learn more about our commitment to sustainable delivery practices.