The first time I went to a builders merchant for a groundwork project, I stood in front of a board listing about twelve types of aggregate and had absolutely no idea which one I needed. I ended up asking a member of staff who, to their credit, took five minutes to explain the basics. I have never forgotten it - and I have been explaining it to other people ever since.
The names do not help. Different suppliers use different terms. What one merchant calls "all-in ballast" another calls "concrete aggregate." What one calls "scalpings" another calls "crusher run." Here is a consistent guide to what you are actually dealing with.
MOT Type 1 (Granular Sub-Base Type 1)
What it is: Crushed stone or recycled concrete with a defined grading specification, originally set by the Ministry of Transport. Contains particles from fine dust up to 40mm.
What it looks like: Angular grey/tan crushed stone with a mix of sizes. Has a dusty appearance when dry.
What makes it special: The grading creates a self-binding material. When compacted, the angular particles interlock and the fine material fills the voids, creating a very dense, stable layer that distributes load excellently.
Used for: Sub-base for driveways, patios, paths, garage bases, shed bases - anywhere you need a compacted load-bearing base layer.
Important: Requires a 1.3x compaction factor when calculating quantities. See the MOT Type 1 Calculator.
Hardcore (Mixed Hardcore)
What it is: Broken bricks, concrete rubble, stone - often from demolition. No controlled specification.
What it looks like: Variable - can contain brick fragments, concrete chunks, tile pieces.
Used for: General rough fill, non-critical sub-base in garden areas, raising ground levels.
The honest assessment: Cheap, but unpredictable. Quality varies enormously depending on the source. For anything structural or where you need consistent compaction - a driveway, a patio you care about, a building foundation - use MOT Type 1 instead. Use hardcore where cost is the primary concern and performance is secondary.
Ballast (All-In Aggregate / Concrete Aggregate)
What it is: A blended mix of coarse aggregate (stone chips) and sharp sand, typically in proportions suitable for concrete mixing.
What it looks like: Mixed small stones and sand together, usually 0-20mm particle range.
Used for: Mixed directly with cement and water to make concrete. Add 1 part cement to roughly 5 parts ballast by volume for general-purpose concrete (though follow specific instructions for your application).
What it is not: A sub-base material. Ballast is for making concrete, not for compacting as a sub-base layer.
Sharp Sand (Concreting Sand)
What it is: Coarse-grained, angular sand with gritty texture.
What it looks like: Pale to mid-yellow, distinctly gritty to touch. Much coarser than soft sand.
Used for:
- Concrete mixes (combined with coarse aggregate and cement)
- Bedding layer under paving slabs (25-40mm layer for levelling)
- Block paving bedding
- Mixed with cement for pointing compounds
The confusion to avoid: Sharp sand and soft sand look similar but feel completely different. Sharp sand feels gritty and rough. Soft sand feels smooth and silky. If you are ordering sand for concrete or for a bedding layer, you want sharp sand.
Soft Sand (Builder's Sand / Plastering Sand)
What it is: Fine-grained smooth sand with rounded particles.
What it looks like: Pale orange to yellow, smooth silky texture.
Used for:
- Laying mortar for brickwork
- Rendering external walls
- Pointing joints between slabs (mixed with cement)
- Plastering
What it is not: For concrete mixes or bedding layers. The smooth rounded particles do not give the structural strength that sharp angular particles provide. Using soft sand in concrete gives a weaker, less workable mix.
Scalpings (Crusher Run / Quarry Waste)
What it is: A by-product of stone quarrying, containing a blend of stone chips and stone dust. Usually 0-40mm or similar.
What it looks like: Similar in appearance to MOT Type 1, but often dustier and less well-graded.
Used for: Budget sub-base for light-duty applications, rough fill, driveway bases where cost matters more than performance.
Compared to MOT Type 1: Cheaper, but less consistent. The particle grading is not controlled, so compaction is less predictable. For a driveway or patio you care about, MOT Type 1 is a better choice. For rough fill or a less critical base, scalpings do the job.
Shingle / Gravel (10-20mm)
What it is: Washed stone of a specific size range, either rounded (natural) or angular (crushed).
What it looks like: Uniform-sized stones, tan to grey in colour. Round or angular depending on type.
Used for:
- Surface layer for gravel driveways and paths
- Drainage layers in soakaways and drainage runs
- Decorative garden borders and bed mulching
- Exposed aggregate concrete finish
What it is not: A sub-base material. Gravel does not compact and does not distribute load the way MOT Type 1 does. It is a surface material or drainage material.
Pea Gravel (6-10mm)
What it is: Small rounded stones, 6-10mm diameter.
Used for: Decorative garden areas, fine drainage, tight spaces around pipes. Not ideal as a driveway surface - too small and mobile under vehicle wheels.
Crushed Limestone
What it is: Crushed limestone aggregate, lighter coloured than other aggregates.
Used for: Decorative driveways, paths, garden areas where appearance matters. Can also be used as a sub-base in some applications. Good drainage properties.
Which one do I need? - Quick reference
| You need to... | Use this |
|---|---|
| Build a sub-base for a driveway or patio | MOT Type 1 |
| Fill and compact an area cheaply | Scalpings or hardcore |
| Mix concrete from scratch | Ballast + cement |
| Bed paving slabs | Sharp sand |
| Make bricklaying mortar | Soft sand + cement |
| Surface a gravel driveway | Shingle / gravel 10-20mm |
| Create a decorative path | Pea gravel or crushed limestone |
| Drainage in a soakaway | 10-20mm shingle |
My tips on avoiding aggregate confusion
After getting it wrong enough times to be useful:
Be specific with your order. Do not order "sand" - order sharp sand or soft sand. Do not order "aggregate" - name the specific material. The wrong delivery is your problem to resolve.
Ask what grade is available. Merchants do not always stock the exact grade you want. Ask before assuming. MOT Type 1 is almost universally available. Specific sizes of decorative gravel or chippings may need ordering.
Check availability before planning your schedule. Loose tipper loads from busy suppliers can be 3-5 working days away, particularly in summer. Do not plan to start a job next Saturday unless you have confirmed the delivery.
For calculating how much of any of these you need, use the Aggregate Calculator, the MOT Type 1 Calculator for sub-base work, or the Gravel Calculator for driveway and decorative gravel.