Road base is a combination of loose and compacted crushed stone and dust suitable as a foundation for roads, footpaths and driveways.

Road base commonly provides both the load-bearing strength and stability required to support heavy loads such as cars, trucks and even light rail systems. The product commonly helps drain away excess water on road surfaces by allowing it to seep through small openings in the rocks while preventing erosion of the surface from rain or melting snow over time.

The most common type of rock used in road base is limestone, which comes from sedimentary rock composed primarily of calcium carbonate. Crushed stone and gravel are also common ingredients. This mix contains some clay and requires an extremely high amount of shale. Road base also uses a small fraction of bitumin, or "asphaltic," material to act as binders, holding the rocks together. It can use blue metal and other materials suitable for roads, which can give strength to the road base. They can differ based on the shape, manufactured by different makers.

What are the benefits of road base?

Crushed stone road base provides several key functions for improved road safety and performance.

Load carrying capacity

Road base is strong enough to support heavy loads without breaking apart. This prevents the roads from cracking when subjected to continuous wear and tear, particularly during freezing conditions. Road maintenance crews often spread some on roads in low-lying areas before snowfall because it freezes at a lower temperature than water, which prevents ice build up on road surfaces while continuing to provide drainage for excess water runoff. Crusher dust works in a very similar way. It is better for driveways since a driveway experiences a lot of vehicle's pressure at the same spot for a long time.


Rocks in the base allow water to drain through them so it doesn't pool on road surfaces and seep into the ground below. Unlike concrete, which prevents water from seeping back up through expansion joints between slabs of pavement, road base allows excess water to flow away without compromising road integrity. It also creates a hard surface that's easier for vehicles to drive than dirt or grass if roads need to be closed due to unexpected flooding during heavy rains or storms. It won't block the drainage and will remain firm for a long time. The dust form blend mixed with the road base can be used on the road surrounding the drainage.


Road base provides stability by keeping the sediment layers underneath it in place while allowing traffic to pass over it. This prevents damage caused by settlement during very wet seasons when loads of water runoff form underneath the surface, causing rocks within the mix to settle and break apart before they can properly compact together.

Road maintenance

The particles in the road base breaks down over time, which allows crews to sweep it up and use it again once surface roads need repaving. This saves money because the product doesn't need to be purchased from quarries or brought in from other sites as gravel does. It also creates a smooth surface that requires less maintenance than standard lower quality dirt roads built atop hard clay soils.

Optionally, the materials within road base may also provide reflective surfaces when used to build highways and roads designed for nighttime driving conditions.

Reflective paint

Lines and names on certain types of roadway reflect light emitted by headlights much better than asphalt or concrete, which helps improve safety by making them more visible to drivers at night. Asphalt can hence be replaced with this crushed stone, which is also cheaper than asphalt.

Cat eye road stud

This reflective marker sticks up above the surface of the roadway and emits a steady, constant light that helps drivers see where they're going. It can be mounted on street poles or other forms of vertical structures and is most beneficial when placed along curves roads to help drivers reduce their speed as they approach those junctions.

The specific type of rock used in road base also plays a key role in determining its strength and durability.


A popular choice for building roads because it's easy to crush into small particles without cracking or flaking apart, limiting wear on vehicles passing over it. Limestone's characteristics make it an ideal item for maintaining smooth surfaces during freezing weather.


A volcanic rock that's hard enough to withstand heavy traffic and resist corrosion caused by oils leaking out of vehicles. They also tend to be more round than other rocks, which helps them maintain stability even when subjected to aggressive vibrations during travel over road surfaces.


An igneous stone used in building roads for its high compressive strength, which means it resists the pressure heating causes before eventually breaking apart. It also provides good drainage qualities without easily eroding away with wear and tear like softer types of rock often do when exposed to continuous contact with moving vehicles.

What is road base gravel used for?

Although road base gravel has a wide variety of uses, the most common is using it as a foundation for roads, car parks and highways. It's typically used with multiple layers of aggregate that provide an even surface to drive on without being too rough or sharp to damage vehicle tires or harm passengers inside those vehicles. They're used in and for retaining walls (any retaining walls), parking areas, driveway, etc. It's used to make a strong base, ideal for landscaping, pavers and surrounding areas, hard stands, paths, etc. Many other types of roads are built atop different forms of material, including dirt which requires regular levelling through grading processes. However, road base can be applied over almost any soil type because its particles bond together by inserting their tiny particle chains into one another like Lego blocks to create strong seams that prevent them from shifting around when disturbed by traffic or torn up during roadway excavation projects. Road base gravel is also used in building dams and levees because its rounded edges help reduce the amount of water penetrating its upper surfaces, which can continue to erode downward to create openings for floods over time if not prevented by structural barriers like dams or levees. The road base material used for these types of projects is often graded based on how small they are, with gravel typically ranging in size from 4 - 10 millimetres (mm) across and sand particles measuring 2 - 4 mm in diameter. Larger rocks found within road base gravel include stones that range between 16 - 20 mm in diameter, which can be separated out during processing to acquire more pure aggregate qualities without including large expanded spaces inside them. Any project such as walkways, paving, garden, driveway or multiple driveways, parking areas, hard stands, bulka bags, etc. use this material.

Where does road base come from?

Road base is usually acquired through quarries where natural rock formations are mined so dust can be extracted from the surrounding deposits. Limestone is typically quarried using drilling processes, while basalt's highly resistant surface can be broken off with explosives. Granite often breaks apart during this process due to the high temperatures generated by friction forces between its mineral components, which are exposed through heating. The material that makes up road base is then ground into small pieces before being separated into different classifications based on their sizes and specific weight measurements. Road base gravel isn't classified in a universal way because of the varied types of stone it consists of, but instead by how large each type of particle appears relative to an individual's eyesight after processing it down to manageable sizes. Particle gradations are also used when identifying different types of gravel, with gradations typically ranging from 1 - 8. This means that road base with particles measuring 1 mm will include all the particles in the gravel deposit that measure between 0.5 mm and 1 mm in diameter, while a grade 3 gravel would be made up of material between 2 mm and 4.9 mm in diameter. The most common grading system is to use number 4 aggregate for roads because its larger size makes it more resistant to wear when subjected to passing traffic over long periods of time during daily commuting schedules.

How much road base do I need?

There are no hard and fast rules on the required quantity of road base gravel you'll need for your project because it depends on the specific requirements of your work, as well as where you plan to apply it. For instance, gardens and pavers would have different road base demand. The price depends on the type of road base solution so you need to check out the price depending on your requirement. Colour is another thing to take care of.

If you're building or paving a basic driveway or repairing an existing roadway, you can usually estimate that 10 tonnes per metre (t/m) of road base will be sufficient for complete construction purposes. This means that a 100 m road would require 1,000 t of rock material for its foundation. The width of the road or the width of the driveway should be considered.

These figures also assume that an average 3-inch thickness is applied for roads and driveways and up to 6 inches may be used for more traffic-heavy areas like highways. The surface of the finished product needs to be taken into account when calculating the amount of road base needed, as well as any additional materials you plan to use for making it.

Using this estimated figure ensures your project has a sound foundation that will be durable enough to endure heavy traffic loads, but it's still possible to alter the makeup of your road base material based on which aspects you want it to improve. For instance, incorporating a 10 - 15 percent mixture of slag into your road base gravel will give it better freeze-thaw resistance as well as improved abrasion resistance for increased durability during winter months when snow and ice are more likely to accumulate. Get the supply of road base once measuring the required quantity.

All these factors must be accounted for when choosing how much road base gravel is needed for your construction projects so part of the finished product can perform its purpose in the most effective way possible. The New South Wales Department of Transport has a handy reference for road design and materials used.