Concrete Mix / Core Fill

Concrete Mix is a pre‑blended combination of coarse sand and 10mm aggregate, ready for onsite batching with cement and water.
It delivers the correct ratio of materials for strong, durable concrete, reducing preparation time and ensuring consistent results.

• Filling concrete blocks or core holes (core fill)
• Fence posts, pathways, and small slab footings
• General building and landscaping projects
• On‑site hand or machine mixing with cement

The balanced blend offers excellent workability and compaction, making it ideal for both domestic and light commercial use.

Available in 20kg bags, bulka bags, or loose tipped. Bulk loose delivery available 6 days a week. Minimum 500kg. Pickup available in any quantity.

Concrete mix buyer’s guide

Concrete mix (also sold as concrete blend or core fill) is coarse washed sand and 10mm aggregate combined at the yard in the correct ratio for concrete. You add cement and water on site. Batching from separate piles of sand and stone leaves the ratio to guesswork; a pre-blend takes that variable out of the pour.

Jobs it suits

• Fence, gate and pergola posts
• Clothesline, letterbox and bollard footings
• Pathways, pads and small slab pours
• Core-filling concrete blockwork
• General repair and patching concrete

How much cement and how much mix?

For general work, mix around 4–5 parts blend to 1 part cement by volume; keep to the stronger end for structural footings. Allow roughly 1.6 tonnes of blend per cubic metre, and one cubic metre of blend plus cement yields close to one cubic metre of finished concrete. A typical fence post hole (300mm across, 600mm deep) takes about 0.04 of a cubic metre — so a cubic metre of mix does roughly 25 post holes.

Concrete mix, road base or straight aggregate?

Three different jobs. Road base is the compacted layer that goes under a slab or paving — our guide to DGB20 vs DGS40 road base covers which grade to use. Concrete mix is what you pour on top of it. And clean stone such as 20mm blue metal is for drainage, or for boosting the coarse aggregate in a stronger mix.

What makes a good blend

A consistent sand-to-stone ratio through the whole load, clean washed sand with no clay, and hard 10mm aggregate with no soil, roots or building rubbish. The blend should look uniform, not striped or lumpy. Ours is mixed at our Jamisontown yard and sold in 20kg bags, bulka bags or loose tipped, delivered across Penrith and Sydney.

Frequently asked questions

What is concrete mix or core fill?

It is coarse washed sand and 10mm aggregate pre-blended in the correct ratio for making concrete — you just add cement and water. The same blend is used to core-fill the hollow cavities in concrete blockwork, which is where the core fill name comes from.

How much cement do I add to concrete mix?

Mix around four to five parts blend to one part cement by volume — four to one for stronger structural work such as footings, five to one for paths and general concrete. Add water gradually until the mix is workable but not sloppy.

How much concrete mix do I need for fence posts?

A standard post hole about 300 millimetres across and 600 millimetres deep takes roughly 0.04 of a cubic metre, so one cubic metre of blend concretes about 25 post holes. Count your holes, multiply by 0.04, and allow around 1.6 tonnes per cubic metre.

Is concrete mix the same as road base?

No. Road base is crushed rock with fines that gets compacted dry as a hard layer under driveways, slabs and paving. Concrete mix is a sand-and-aggregate blend made to be mixed with cement and poured. The base goes down first, the concrete on top.