Which crushed rock and fill actually holds up in Casey’s reactive clay
Short answer: for a house driveway, shed pad or slab base anywhere from Berwick to Hampton Park, use 20mm Class 3 crushed rock, 150mm deep, in two compacted lifts. Delivered in 2026 that is $52 to $70 a tonne, or about $30 to $45 a square metre supplied, spread and compacted. Recycled Class 3 crushed concrete does the same job for $30 to $45 a tonne and is the right call on most homes. Crusher dust is not a base and never has been.
Every base and fill material we buy, side by side
Delivered rates are for 10 to 20 tonne loads to a Casey address in 2026, including cartage from the quarry and recycling yards around Officer, Pakenham and Lyndhurst. Single tonne bag rates are roughly double. Expected life assumes the material is laid on a prepared subgrade and compacted in lifts, because none of it performs if that part is skipped.
| Material or method | Typical 2026 delivered cost | Expected life in Casey conditions | Maintenance load | Warranty you can actually get | Who it suits |
|---|---|---|---|---|---|
| 20mm Class 2 crushed rock | $62 - $80 / tonne | 25 years plus under a sealed surface | Very low | Quarry batch test certificate on grading and strength. No life warranty on any rock. | Commercial crossovers, truck and caravan driveways, anything under asphalt |
| 20mm Class 3 crushed rock | $52 - $70 / tonne | 20 years plus under concrete, pavers or asphalt | Very low | Batch test certificate on request | The default for domestic driveways, shed pads and house pads |
| 20mm Class 4 crushed rock | $42 - $58 / tonne | 10 to 15 years if it is the only layer, indefinite as buried fill | Low to medium: it ruts under point loads | Fit for purpose only | Deep fill lifts under a Class 3 capping, farm and paddock tracks |
| Recycled Class 3 crushed concrete (20mm) | $30 - $45 / tonne | 20 years plus, comparable to quarry Class 3 when graded and screened | Low | Recycler’s product spec sheet and delivery docket | Most residential driveways and pads. The value pick in Casey. |
| Crusher dust / quarry screenings | $45 - $62 / tonne | 2 to 5 years if wrongly used as a base | High: it pumps and rutts once wet | None worth having | Paver bedding at 20mm to 30mm, pipe haunching. Never a base. |
| Washed river sand | $65 - $88 / tonne | Not a structural layer | Not applicable | None | Pipe bedding, pool floor screed, under paving where the engineer calls for it |
| Clean screened fill soil | $22 - $45 / cubic m | Indefinite if compacted in 100mm lifts and capped | Low once it has been through one wet season | EPA compliant classification paperwork from the source site | Bulking up a low corner, garden levels, non-structural fill only |
| Lime or cement stabilised subgrade | $14 - $26 / m² | 20 years plus. It fixes the problem instead of covering it. | Very low | The geotechnical test result is your evidence | Class H1 reactive clay in Endeavour Hills, Hampton Park and Hallam |
| Non-woven geotextile separation fabric | $3.50 - $7 / m² | Design life of the pavement above it | None | Manufacturer spec on tensile strength and flow rate | Any soft or reactive clay subgrade. Cheapest insurance on this page. |
Indicative 2026 rates for the City of Casey, GST inclusive, delivered in bulk loads. Call 0485 813 822 with your area and depth and we will price the exact tonnage.
What the Class number on the docket actually means
The Class number is a grading and quality band from the state road authority standard specifications, not a strength number you can read off the pile. Two things separate the classes: the particle size distribution, meaning how much of the load is 20mm stone, how much is intermediate and how much is fines, and the minimum strength and plasticity limits the material has to meet. Class 2 is the tightest band and is designed to sit directly under asphalt on a road. Class 3 is a sub-base band, slightly wider on fines, and it is what a domestic concrete driveway or a shed pad wants. Class 4 allows more fines and a lower minimum strength, which is fine 400mm down in a fill lift and poor in the top 150mm where the wheel loads are.
The number that actually matters on a Casey block is not printed on the docket at all. It is the strength of the ground underneath. Crushed rock does not carry a car by itself, it spreads the load out over a wider patch of subgrade. If the subgrade is soft, wet, reactive clay, no thickness of rock will save it, which is why we always look at what is under the rock before we argue about which rock.
Casey’s ground, and why it decides the spec
The belt running from Hallam through Endeavour Hills, Hampton Park and the eastern edge of Cranbourne sits on reactive clay, commonly classified Class M through to H1 under the residential slab and footing standard. That ground swells and shrinks 30mm to 50mm between a wet August and a dry February. North Berwick and parts of Cranbourne South are kinder, more silty loam over sand, and they drain properly. Officer, Clyde and Cranbourne East are a patchwork, and a lot of the newer estates sit on old market garden ground with 300mm to 500mm of worked topsoil that has no bearing value whatsoever.
Casey gets roughly 700mm to 800mm of rain a year, most of it between May and October. That matters more than the annual total, because it means the subgrade spends five months of the year near its wettest and weakest. A base that is fine in March fails in August. So the local specification question is really: how do I keep water out of the subgrade, and how do I stop the clay pushing up into my rock. The answers are drainage falls, a separation fabric, and enough compacted depth that the load is spread before it ever reaches the clay.
Not sure what your ground is?
We hand test the soil at the free site visit and tell you the grade and depth your block needs, in writing, before you buy a tonne of anything.
The cheap specification that fails early here, and why
We get called to look at the same four mistakes almost every month, and all four were cheaper on the day.
- Crusher dust used as a base. It is about $10 a tonne cheaper than Class 3 and it spreads beautifully, which is why it sells. It has almost no coarse aggregate to interlock, so once water reaches it, it behaves like wet sand under load. Two to five years and the driveway is dished where the wheels run.
- Unscreened demolition rubble sold as recycled fill. Graded recycled Class 3 from a licensed recycler is an excellent product. Unscreened rubble with brick, plaster, timber and steel in it is not the same thing at a lower price, it is a different thing. It will not compact evenly, and the soft inclusions crush and leave voids. Ask for the docket with the product name on it.
- Rock laid straight onto topsoil. This is the most expensive $600 anyone ever saves. Topsoil is organic, it holds water and it keeps breaking down. Rock placed on it sinks into it. The fix is to strip 100mm to 300mm to firm subgrade first, which is exactly the step a very low quote leaves out. See the signs of bad earthworks for what that looks like from above, two winters later.
- One 200mm lift instead of two 100mm lifts. A plate compactor or a small roller only compacts the top 100mm or so properly. Dropping the whole depth in one go gives you a firm crust over loose material. It passes the boot test on the day and fails under a car in August.
What “commercial grade” and “heavy duty” are worth
Nothing, on their own. They are not defined terms and no supplier is bound by them. The three things that are real, and that you can ask for on any job, are the product name on the delivery docket, the compacted depth in millimetres written into the quote, and the number of lifts. If a quote says “commercial grade base, driveway prepared” and does not say “150mm of 20mm Class 3 crushed rock in two compacted lifts over stripped and rolled subgrade”, you have no way of checking what turned up. A quote you can check is worth more than a quote that is $300 cheaper.
The same goes for “fully compacted”. Compaction has a measurable standard. On driveway sub-base we target 95 percent of standard maximum dry density, and on a foundation pad 98 percent. On commercial work a geotechnical tester puts a number on each lift. On a domestic job you will not normally pay for lab testing, but the quote should still name the target and the lift thickness so there is something to hold us to.
What we would actually put under a typical Casey house
Take a standard 60 square metre concrete driveway on a Narre Warren South or Berwick block, single storey house, one or two cars, no truck access. Our recommendation, in order:
- Strip 150mm of topsoil and any old fill to firm subgrade, then proof roll it. If a patch moves under the machine, that patch gets dug out further or stabilised, not covered up.
- Lay a non-woven separation geotextile over the clay. About $210 to $420 on a job this size, and it is the difference between a 150mm base staying 150mm and turning into 80mm of rock mixed with clay.
- 150mm of 20mm Class 3 crushed rock, or recycled Class 3 crushed concrete, in two lifts of 75mm, each one watered to moisture and rolled before the next goes on. That is 9 cubic metres compacted, about 21 tonnes, so order 23 with wastage.
- Grade a fall of at least 1 in 100 away from the house and towards a legal discharge point. A perfect base under a driveway that ponds water is a base with a countdown on it.
All up, that is roughly $1,200 to $1,610 in rock, $210 to $420 in fabric, and $1,400 to $2,600 in machine and labour for the strip, cart away, spread and compaction. Choosing recycled instead of quarry rock takes about $500 off. The labour side is set out on our driveway preparation page and in the 2026 pricing guide.
On the reactive clay through Endeavour Hills and Hampton Park, add lime stabilisation of the subgrade if the proof roll shows the ground is soft. It costs $14 to $26 a square metre, so $840 to $1,560 on this driveway, and it is the only item on the list that changes the clay itself rather than working around it. On a block that already drains well, it is money you do not need to spend.
When you do not need any of this
If your existing driveway is sound and only the surface is tired, the base underneath is already doing its job and digging it out is a waste. Cracking at the control joints is normal concrete behaviour, not a base failure. A garden path, a bin pad or a shed floor that will never see a vehicle does not need 150mm of Class 3 either: 75mm to 100mm is plenty. And if you are levelling a lawn or building up a garden bed, buy screened fill soil at $22 to $45 a cubic metre and keep the rock budget for the parts that carry weight. We will tell you that on the phone rather than sell you a job you do not have.
Six questions to ask whoever is quoting
- What product exactly, by name, and will the delivery docket show it?
- What compacted depth, and how many lifts?
- How deep are you stripping before the rock goes down, and what happens if you find soft spots?
- Is separation fabric included or excluded?
- Who pays if the tonnage runs over, and how is the extra measured?
- What fall are you grading to, and where does the water end up?
Six questions, and the answers tell you more about a quote than the number at the bottom of it. If you want to size the job yourself first, our soil volume and truck load estimator will get you close, and the budget earthworks guide shows where it is safe to save and where it is not. For the whole job start to finish, see site cut and fill.
Crushed rock and fill questions
What crushed rock should I use under a driveway in Berwick?
What does the Class number on crushed rock actually mean?
Is recycled crushed concrete as good as quarry rock?
Can I use crusher dust as a driveway base?
How much crushed rock do I need for a 60 square metre driveway?
Do I need geofabric under the crushed rock?
Get the exact tonnage and grade priced for your block
Send us the area and depth and we will come back with the product, the tonnage, the lifts and a fixed price, usually within one business day.
Get the spec right before the rock arrives
Free on-site visit across Berwick, Cranbourne, Narre Warren, Hampton Park and Endeavour Hills. Fixed written quote within 48 hours.