Best Aggregates to Use for Driveways 

19th Jul 2024 -

When it comes to driveway construction, choosing the right aggregate is important for both aesthetics and durability. This article examines the top aggregates that deliver exceptional results for driveway construction. Whether you are looking to boost your skillset or expand your material knowledge, this guide provides valuable insights. 

• 6 Different Aggregates for Driveways
• How to Choose the Best Aggregate for Your Driveway
• How to Lay Driveway Aggregates: Top Tips
• How Much Aggregate Do You Need?
• Shop Reliable and Long-Lasting Driveway Aggregates

6 Different Aggregates for Driveways

Each aggregate type offers unique properties that suit different needs, environments and design preferences. Below, we explore the most popular aggregate types used in driveway construction, detailing their strengths and ideal applications.

1. Gravel

Gravel is a common and versatile aggregate used for driveways. It consists of small, rounded stones typically ranging from 6-40mm in diameter. Its excellent drainage properties help prevent water accumulation, reducing the risk of erosion.

It is easy to install and maintain a gravel driveway, allowing for simple additions as needed. Gravel comes in different colours and variations. 

• Limestone gravel: Angular, light-coloured aggregate that compacts well and provides excellent drainage for driveways.
• Cotswold buff gravel: Cream/beige-coloured, crushed limestone chippings offering a warm, natural look for driveways.
• Asphalt gravel: A mixture of stone aggregate and asphalt cement, creating a durable, semi-flexible surface for driveways.
• Basalt gravel: Dark, fine-grained volcanic rock that offers excellent durability and a modern appearance for driveways.
• Staffordshire pink gravel: Distinctive pink-hued gravel offers a unique colour and good durability for decorative driveways.
• Welsh brown gravel: Rich, brown-coloured gravel providing a natural, earthy tone suitable for rustic or traditional driveway designs.

2. Crushed stone

Referred to as type 1 aggregate or MOT Type 1, crushed stone comes in various sizes, typically between 10-40mm. Its angular shape allows the pieces to interlock well, creating a stable surface that is resistant to displacement. This makes crushed stone an excellent choice for high-traffic driveways and areas prone to erosion. 

Like gravel, crushed stone offers excellent drainage capabilities, helping to manage water runoff effectively. It can be compacted to create a firmer surface, providing enhanced stability compared to rounded gravel. This aggregate is ideal for driveways that require a more structured and durable surface.

3. Decomposed granite (DG)

DG is granite rock that has weathered into smaller particles, producing a material with a texture between sand and gravel. It creates a natural and earthy appearance. DG is available in various colours, including reds, browns and tans. 

When properly installed, it compacts well to form a firm surface while still maintaining good drainage properties. Decomposed granite chippings can be stabilised with additives for increased durability, enhancing its longevity and performance. 

4. Recycled concrete aggregate (RCA)

RCA is made from crushed concrete sourced from demolition sites, offering an environmentally friendly option for driveway construction. It boasts good compaction and load-bearing capacity, making it suitable for various driveway applications. 

The aggregate has excellent drainage properties, reducing the risk of puddles or runoff issues. RCA can be used as both a base layer and a top layer in driveway construction, offering versatility in its application. 

It is particularly well-suited for industrial or modern designs, as well as for building sturdy base layers for paved driveways.

5. Pea shingle

Also known as pea gravel, it consists of small, rounded stones typically 10-20mm in diameter. It offers an attractive, smooth appearance that can enhance the visual appeal of any driveway. Available in various colours, pea shingle provides excellent drainage properties for managing water runoff. 

The smooth, rounded nature of pea gravel makes it comfortable to walk on. Using pea shingles is an economical way to create attractive driveways. It is particularly well-suited for decorative driveways and areas with flat or gently sloping terrain.

6. Slate chippings

Slate chippings are flat, angular pieces of slate rock, generally ranging from 10-50mm in size. They offer a distinctive appearance that enhances the visual appeal of a driveway. Slate chips are available in various colours including blues and greys. 

The angular nature allows them to interlock well, creating a stable surface resistant to displacement. It is also highly resistant to weathering and fading. Like other aggregates, slate chippings offer good drainage properties, helping to manage water runoff effectively. 

Explore our full range of shingle and gravel driveway aggregates to suit your project.

How to Choose the Best Aggregate for Your Driveway

Each material offers unique characteristics in terms of durability, drainage, aesthetics and maintenance requirements. The following comparison table examines the above 6 aggregate types.

Aggregate type	Pros	Cons
Gravel	- Excellent drainage (permeability rate of 50-70%).  - Easy installation.  - Natural appearance and a variety of colours and sizes.	- Prone to displacement.  - Requires regular replenishment every 1-3 years. - Can create dust in dry conditions.
Crushed Stone	- Superior interlocking (angular shape).  - High compaction rate.  - Excellent load-bearing capacity.  - Good drainage (permeability rate of 30-50%).  - Resistant to displacement.	- Can be rough on vehicle tyres.  - May require geotextile underlayment (driveway grids) for stability.
Decomposed Granite	- Natural, earthy appearance. - Excellent permeability (70-80% when uncompacted). - Compacts well (up to 95% proctor density). - Good for water conservation.	- Requires regular maintenance (every 1-2 years).  - Can be dusty in dry climates. - Less durable than crushed stone (lifespan 7-10 years).  - May erode if not properly stabilised.
RCA	- Eco-friendly option. - High load-bearing capacity.  - Good drainage (permeability rate of 20-40%). - Excellent for base layers.	- Variable quality of aggregate. - Less visually appealing for the surface layer.  - Can be alkaline, affecting the surrounding soil pH.
Pea Shingle	- Smooth, attractive appearance.  - Good drainage (permeability rate of 60-70%).  - Various colours.  - Low dust production.	- Easily displaced due to rounded shape.  - Not suitable for slopes and requires robust edging.  - Regular replenishment every 2-3 years.
Slate Chippings	- Excellent durability  - Good interlocking properties.  - Resistant to weather and UV fading.  - Low maintenance once settled.	- Sharp edges when newly laid.  - Heavier than other options.  - Requires proper base preparation for stability.

How to Lay Driveway Aggregates: Top Tips

To elevate aggregate driveways, advanced techniques make a significant difference. Below, we outline methods and best practices for each type of driveway aggregate. They offer ways to enhance stability and durability while addressing common challenges. 

Gravel

• Geogrid stabilisation: Install a gravel driveway grid layer beneath the gravel. This synthetic mesh increases load distribution and reduces rutting. If possible, use a biaxial geogrid matching your gravel grade.
• Gradual layering: Apply gravel in 50-75mm layers, compacting each layer to 95% proctor density (maximum dry density) before adding the next. This creates a more stable base. 
• Edge reinforcement: Install rigid edging (metal, plastic or concrete) buried at least 75mm below grade. It prevents gravel migration and maintains driveway shape.
• Dust suppression: Apply a liquid dust suppressant (e.g. calcium chloride or lignin sulfonate) annually. This reduces dust and helps bind particles, improving stability.
• Permeable underlayment: Install a layer of crushed stone beneath the gravel to boost drainage and prevent it from sinking into softer subgrades.

Crushed stone

• Compaction optimisation: Use a vibratory roller with the correct frequency, usually 2000-3000 vibrations per minute (VPM) for your stone size. Compact in 100mm lifts to achieve maximum density.
• Gradation blending: Mix different grades of crushed stone to create an optimal gradation curve. This improves compaction and reduces void spaces.
• Geotextile separation: Install a non-woven geotextile between the subgrade and crushed stone to maintain drainage capacity.
• Surface sealant: Apply a penetrating stone sealant to the top layer. This reduces dust and increases surface stability.
• Interlayer binding: Use a small amount of Portland cement mixed into the top layer before compaction. It creates a semi-bound surface with improved stability.

Decomposed granite (DG)

• Stabiliser integration: Mix a synthetic stabiliser thoroughly with DG before installation. This reduces erosion and dust while maintaining permeability.
• Moisture control: Install DG at the optimal moisture content (typically 10-15%) and use a roller with both static and vibratory capabilities for best compaction. 
• Layered installation: Apply DG in thin layers (25-50mm), compacting each layer to 95% proctor density for a uniform and stable surface.
• Binder application: For high-traffic areas, consider using a resin binder (e.g. polyurethane-based) to create a durable surface.
• Drainage optimisation: Install a 50-100mm base layer of compacted crushed stone beneath the DG to help drainage and prevent saturation.

Recycled concrete aggregate (RCA)

• pH neutralisation: If alkalinity is a concern, introduce granulated sulphur (1-2% by weight) into the RCA to neutralise pH levels over time.
• Compaction technique: Use a heavy vibratory roller (minimum 10-ton) with 3-5 passes. Water the RCA during compaction to achieve optimal moisture content for maximum density.
• Geogrid reinforcement: For heavy load applications, install a triaxial geogrid between the subgrade and RCA to improve load distribution.
• Surface treatment: Apply a thin layer (25-50mm) of finer aggregate or stone dust on top of the RCA and compact it. This creates a smoother surface. 

Pea shingle

• Resin binding: Mix the pea shingle with a clear, UV-stable resin binder. This creates a permeable yet stable surface that resists displacement. 
• Layered installation: Create a base layer of angular crushed stone (50-100mm) before adding the pea shingle. It improves load-bearing capacity and reduces sinking.
• Edge design: Introduce a "hidden edge" system using perforated metal or plastic edging buried below the pea shingle surface. This contains the aggregate without visible borders.
• Compaction method: Use a plate compactor with a rubber mat attachment to settle the pea shingle without crushing the stones, improving stability.

Slate chippings

• Gradation optimisation: Use a mix of slate chip sizes (e.g. 20mm, 40mm and 60mm) to improve interlocking and reduce void spaces. 
• Resin bonding: For high-traffic areas, consider using a clear, flexible resin to bond the top layer of slate chips. This improves stability while maintaining drainage.
• Underlayment design: Install a geotextile fabric topped with a layer of 20mm crushed stone before applying slate chippings. It enhances drainage and prevents the slate from sinking into softer subgrades.
• Compaction technique: Use a rubber-matted plate compactor to settle the slate chips without breaking them. It preserves the angular shape for interlocking.
• Surface treatment: After installation, apply a penetrating sealer designed for slate. This enhances colour, reduces dust and improves slip resistance.

How Much Aggregate Do You Need?

Accurately calculating the amount of aggregate needed for a driveway is important for proper project planning. This process involves several steps and considerations.

1. Measure driveway dimensions

Start by accurately measuring the entire length of the driveway. If the width varies, take measurements at several points to ensure precision. Determine the required depth of aggregate, which typically ranges from 100-150mm for residential driveways. These measurements form the foundation of your calculations.

2. Calculate the volume

Use the formula: Volume = Length x Width x Depth. If you are working in feet, this will give you the volume in cubic feet. To convert to cubic yards, divide the result by 27 (27 cubic feet in 1 cubic yard). For example, a driveway 50 feet long, 12 feet wide, with a 0.33 feet depth would need 7.33 cubic yards of aggregate.

3. Account for compaction

Aggregate will compact when laid and rolled. To compensate for this, add 10-15% to your calculated volume. In the above example, 7.33 cubic yards plus 15% would equal 8.43 cubic yards. This ensures you have enough material after compaction.

4. Consider material type

Different aggregates have varying compaction rates. For crushed stone, add 5-10% to your calculation. Gravel requires an additional 10-15%, while DG needs 15-20% extra. Adjust your figures based on the aggregate material you are using.

5. Allow for edges and curves

If your driveway has curves or irregular edges, add 5-10% to your calculation. Extra material allows enough coverage and allows for any adjustments needed during installation. For sloped driveways, calculate the surface area rather than the horizontal area for accuracy.

6. Consider the base and top layers

If you are using different materials for the base and top layers, calculate each material separately. A typical ratio is 70% base material and 30% top layer. This approach allows for proper layering and a stable foundation.

7. Plan for extras

It is always better to have a slight excess than to run short. Consider ordering 5-10% extra for potential miscalculations or future repairs.