Aggregate materials are behind some of the most important structural work on any property. From the base layer under a new driveway to gravel packed around a drainage pipe, aggregates do the heavy lifting that nobody sees once the job is done. For Central Coast homeowners, builders and landscapers, knowing which aggregate to use and when makes the difference between a project that holds up and one that needs redoing.
What Are Aggregates?
Aggregates are granular materials made from crushed or quarried rock, ranging from fine crusher dust through to large drainage gravel. Each grade suits specific applications in construction and landscaping.
The strength, drainage properties and compaction behaviour of an aggregate change depending on how it has been crushed and graded. Choosing the right type directly affects how a surface performs, how water moves through a site, and how long any structure above it lasts.
Types of Aggregate Available at Kincumber Sand and Soil
Kincumber Sand and Soil stock a range of aggregate supplies on the Central Coast to suit both residential projects and trade requirements.
Blue Metal
Blue metal is a quarried, crushed basalt aggregate available in several sizes, commonly 7mm, 10mm, 14mm and 20mm. It is a clean, angular material with excellent drainage properties and strong compaction characteristics.
- 20mm blue metal is widely used as a concrete aggregate for driveways and structural slabs, and as a drainage aggregate over agricultural pipe
- 14mm blue metal suits concrete mixes for pathways and smaller driveways, and performs well as drainage aggregate around PVC pipes
- 10mm blue metal works well in garden drainage applications, particularly at the base of deep raised garden beds, and in concrete mixes where a finer finish is needed
- 7mm blue metal is suited to finer concrete mixes and lighter drainage work
Road Base (Quarter Minus)
Road base, also known as quarter minus, is a blend of crushed rock particles and blue metal fines. Unlike clean blue metal, it contains a range of particle sizes that compact tightly together, making it ideal for creating stable, load-bearing surfaces.
Common applications include sub-base preparation under concrete slabs, under pavers, and as a compacted driveway surface. Its ability to lock together under compaction makes it one of the most practical materials for any project requiring a firm, level base before a surface is applied. Boral Australia’s quarry materials overview outlines the engineering standards that quality aggregate products are produced to across Australia.
Quarried Drainage Gravel
For properties where water management is a priority, quarried drainage gravel provides a free-draining medium around agricultural pipe, sock pipe and soak wells. It is coarser than blue metal and allows water to move through it quickly, making it particularly useful for sites prone to standing water or where sub-surface drainage systems are being installed. The NSW EPA’s stormwater management guidance provide useful context on managing water flow and drainage effectively across residential and commercial properties.
What Are Aggregates Used For?
The range of applications for aggregate on a residential property is broader than most people expect.
Driveways and parking areas: Road base laid and compacted in layers provides a solid, durable surface that handles vehicle weight and sheds water effectively. A layer of blue metal on top can be added for a finished gravel appearance.
Concrete mixes: Blue metal aggregate is an essential component of any concrete pour, providing structural strength within the mix.
Under paving and slabs: A compacted road base layer beneath pavers, tiles or concrete slabs prevents movement and settling over time, keeping surfaces level and stable.
Drainage systems: Blue metal and drainage gravel packed around agricultural pipe allow water to move freely toward the outlet, preventing soil saturation and waterlogging in low-lying areas.
Garden bed drainage: A layer of coarse aggregate at the base of a raised garden bed improves drainage significantly, particularly in the clay soils common across parts of the Central Coast.
How Much Do You Need?
Getting quantities right before ordering saves time and unnecessary trips. For most applications, the coverage depends on the depth of material being laid and the area being covered. The team at Kincumber Sand and Soil are happy to help with quantity calculations over the phone, and the drive-through yard makes loading a trailer straightforward. Delivery is also available across the Central Coast for larger orders.
For projects that combine aggregate work with other materials, the sand and gravel range at Kincumber covers washed sand, concrete sand and landscaping sand as well.
Where to Buy Aggregate Supplies on the Central Coast
Kincumber Sand and Soil has been supplying the Central Coast building and landscaping industry for more than 30 years. The yard stocks a comprehensive range of aggregate supplies alongside building supplies and landscaping materials, all available from the one convenient drive-through location at 4 Kerta Rd, Kincumber.
Whether the project is a full driveway, a drainage fix or a single garden bed, the team is on hand to help identify the right product and quantity for the job.
Talk to the Team Today
Call Kincumber Sand and Soil on (02) 4368 1252 or visit 4 Kerta Rd, Kincumber. Open Monday to Friday 6:30am to 4:00pm and Saturday 6:30am to 12:00pm. For the full range of landscape supplies in Kincumber, visit the website or come in and have a look.
