Have you ever traversed a beautifully laid driveway, walked across a hard pavement or closely observed a construction crew preparing a site before the arrival of the concrete trucks? Well, in each instance you have experienced roadbase albeit without realizing it! Roadbase is perhaps one of the most common materials utilized in Australian construction, landscaping and civil engineering projects - and almost everyone outside the industry has never thought to question their exact composition! In this guide we explore the constituents of roadbase, the different varieties on the market, where it is incorporated and its undeniably affordable yet durable nature.
What Is a Roadbase?
Roadbase is a mixture of crushed rock, gravel, sand, and fine particles (also known as 'fines') blended together in certain ratios. When consolidated, the various particle sizes interlock causing it to be a strong, stable surface that, when consolidated, will not shift, crack, or erode.
The good thing about roadbase is not an ingredient as much as the combination. The big aggregates give the strength and the carrying capacity, and the fines and small aggregates pack into the gaps between the coarser particles helping to tie the layer together and decrease the movement. So that's the reason it compact so nicely compared to normal sand and loose granular gravel on their own.
It will normally be supplied as a graded product - spread over a range of particle sizes from coarse to fine (unlike a single size stone such as aggregate).
What Is Roadbase Made Of?
Roadbase composition will vary depending on the actual material used, and the region in which it is used, however the majority of roadbase material can be classified by the following:
- Backyard rock or quarry chipping - recycled or newly crushed stone combined into a graded specification
- Ferricrete (also known as laterite and ironstone gravel) - a naturally occurring, iron-rich gravel used extensively in Western Australia because of its high compactability
- Crushed limestone for use in coastal and sandy regions. Good drainage property and easy to work with.
- Recycled crushed concrete or brick an environmentally friendly alternative that compares favorably to virgin quarry rock
- Trusted suppliers get their roadbase tested and graded to local engineering standards before delivery to a construction site.
Types of Roadbase
However, not all roadbase is the same, and selecting the right one for your project will have a big impact on the durability and strength. Here are the main types you are likely to encounter:
- Ferricrete Roadbase
Ferricrete is the top choice of roadbase material across Western Australia. It is a naturally occurring gravel formed from iron rich deposits of soil and considered highly compactable when laid and rolled for a stable surface. Ferricrete is most often supplied in graded sizes of 12mm, 19mm or 25mm, with the size depending on depth of the base course layer. Typical road applications include driveways, rural access tracks and general pavement.
- Bluemetal Aggregate Roadbase
Bluemetal (crushed basalt or other hard rock ) roadbase consists of angular cracked stone with fines produced in the same operation that is used for a dense high strength base layer. Common areas where this is specified are those where additional load bearing capacity is required including heavy vehicle access roads, commercial sites and highways with a high volume of large vehicles using them.
- Crushed Limestone Roadbase
Generally used in sandy coastal environments, crushed limestone roadbase consolidates quite easily in light use situations with moderate drainage. It can be installed in pathways, modest residential driveways or as a sub-base beneath pavement.
- Recycled Roadbase
On site recycled product. This is crushed and screened recycled concrete, brick and asphalt which reproduces virgin rock performance on compaction. It is a far more environmentally friendly and cost effective alternative to virgin rock and is in increasing use in construction.
Common Uses of Roadbase
Roadbase, as the name suggests, was traditionally used for road building, however its uses don't end there. Common applications include:
- Driveways - a strong, stable foundation beneath a gravel, paving stones or asphalt surface
- Roads and access tracks--forming the structural sub-base and base layers beneath sealed or unsealed roads
- Car parks and hardstands -number one support for vehicle loading throughout commercial and industrial areas
- Building pads and slab preparation - preparing a flat, firm foundation that is well compacted before concrete is laid
- Pathways and walkways-Provides a solid, easy to care for surface in walking areas
- Drainage and civil excavation - applications around pipes, retaining structures and site levelling
- Landscaping work-shaping garden beds, back fill for retaining walls and general site fill
Benefits of Using Roadbase
Roadbase has been a construction essential for decades and for good reason. Here's why builders, landscapers, and civil contractors keep coming back to it:
Excellent Compaction and Stability
The graded blend of particle sizes pack together tightly to form a dense interlocking layer, reducing movement, rutting and settlement over time - even when subjected to heavy traffic.
Strong Load-Bearing Capacity
Once it has been thickly and firmly compacted, the roadbase can carry all sorts of loads from thousands of pedestrians to large trucks.
Good Drainage Performance
A well-graded roadbase will drain away through and away from the surface rather than pond on top, preventing erosion and damage from water.
Cost-Effective
Roadbase provides a long lasting finish at much less material and labour cost than sealed or concrete areas - suitable for driveways, rural developments, large site works.
Versatile and Widely Available
Roadbase is suitable for projects of all sizes, from residential driveways to large-scale civil infrastructure, and is available immediately in bulk from local quarry and transport suppliers.
Low Maintenance
If laid and compacted correctly, a roadbase surface will require little maintenance, only increasing an addition or regrading over the years.
How to Choose the Right Roadbase for Your Project?
Different types and grades of roadbase should be considered as there are several to choose from. The most suitable type or grade of roadbase for any one construction project or activity is determined by:
- Purpose - a residential driveway will have very different requirements to that of a hardstand in a commercial setting or country access roads
- Expected load - if heavier vehicle traffic is anticipated, a tougher material such as bluemetal or coarser ferricrete is required.
- Drainage conditions-sites that already drain well naturally could show an improvement if site was made using a more free draining material.
- Base depth - finishing layers are normally made from finer grade while thickest base layers will be of coarser grade.
- Affordable and sustainable - recycled roadbase presents a feasible, green alternative
A suitable supplier will be able to advise on the most appropriate roadbase grade for your project, the soil types involved and the requirements of the local council.
Get Quality Roadbase Delivered Across Perth
If you need road base or gravel then wait no more. We have a comprehensive supply of a variety of gravel and roadbase including; 12mm, 19mm, 25mm ferricrete and bluemetal aggregate roadbase which can be delivered anywhere around Perth. We provide the expertise to stand behind every product with an efficient and dependable service through our trusted local team.
With over 20 years experience in earthworks and haulage industry we have the experience to get your delivery of roadbase to where and when you want it we can offer the best price and advise you honestly.
Want to hear more? Contact Formula Transport today for a FREE quote on any of the above. For all your Needs when it comes to roadbase, gravel and sand.
FAQs
What's the difference between roadbase and gravel?
Gravel is a size uniform and single type of stone. It is used for decoration or drainage. Roadbase is a graded mixture of a number of different sizes of particles manufactured to be compacted tightly to build a structure.
How deep should a roadbase layer be?
Depth is largely application specific. As a general rule a driveway should be compacted to between 100-150mm and other more heavy-duty applications such as commercial hardstands, access roads require between 150-300mm depending on loading the weight and type of soils.
Can the roadbase get wet or is it waterproof?
Roadbase is not waterproof though when properly consolidated a compacted layer will drain fairly well and will be relatively unaffected by water compared to loose fill, although, in the long term it would still need a sealed or paved surface.
Do I need to compact the roadbase myself?
Absolutely, compaction is necessary. Roadbase should be spread in layers and compacted by a plate compactor or roller; un-compacted roadbase will move, rut and settle irregularly when loaded.
What's the best roadbase for a driveway?
Ferricrete is in high demand as a Perth driveway material because it is easily compacted. Your specification depends on base depth and anticipated traffic too. 12mm, 19mm or 25mm grade.
Is recycled roadbase as good as virgin roadbase?
Recycled roadbase, crushed concrete or brick, is suitable for most applications and performs as well as virgin quarry rock. It is the most economic and environmentally friendly material but a little different design strength may be used by each supplier.
How much roadbase do I need for my project?
Calculate area (m) Depth (m)= volume in cubic meters. Suppliers can assist in converting this figure into tonnes. They may also advise on the appropriate grade for your project requirements.
