7mm Scoria is a lightweight volcanic rock aggregate made from naturally vesicular (porous) lava rock, screened to an approximate 7mm nominal size.
20mm Aggregate
20mm Aggregate is a crushed rock product engineered for strength, durability, and versatility across a wide range of civil, building, and landscaping applications. Consisting of angular, 20mm nominal size stones, this aggregate is produced by mechanically crushing hard rock, resulting in sharp-edged, irregular particles with excellent interlock and load-bearing capacity.
Additional Information
Additional information
The material typically presents in natural grey tones—from light to mid-grey with subtle darker flecks—and is formulated to deliver long-term performance in both structural and drainage roles. Its consistent sizing, angularity, and robust mineral composition make it a go-to product for concrete mixes, drainage layers, and bio-retention systems such as rain gardens.
Key characteristics:
- Nominal 20mm angular crushed rock
- High strength and durability
- Excellent interlock and load-bearing performance
- Ideal for concrete, drainage, and rain garden applications
Usage
20mm Aggregate is widely specified by builders, concreters, civil contractors, and landscapers for both structural and hydraulic functions:
Concrete Production
- Used as a coarse aggregate in structural and general-purpose concrete mixes.
- Contributes significantly to compressive strength, stiffness, and long-term durability of concrete.
- Commonly used in slabs, footings, driveways, pavements, and structural elements when mixed with sand, cement, and water.
Drainage Applications
- Ideal for subsoil drainage, behind retaining walls, around agi pipes, and in trench drains.
- The voids between angular stones promote efficient water movement while maintaining structural stability.
- Can be wrapped with geotextile fabric to reduce fine material migration.
Rain Gardens & Bio-Retention Systems
- Used as part of the drainage and filter layer in rain gardens and bio-retention basins.
- Supports controlled infiltration and storage while providing a stable medium beneath soil and planting layers.
Base and Sub-Base Layers
- Suitable for use as a base layer under driveways, access tracks, and hardstand areas, often in combination with finer crushed rock or road base above.
- Provides a strong, free-draining foundation that resists rutting and deformation under load.
Application Tips:
- Compact in layers where used as base or structural support to achieve optimal interlock and stability.
- For drainage applications, consider wrapping the aggregate layer with geofabric to minimise contamination by fines.
- Follow engineer or designer specifications for layer thickness, grading, and compaction in civil and structural works.
20mm Scoria is a lightweight volcanic rock aggregate screened to an approximate 20mm nominal size.
7mm Aggregate, commonly known as ¼ minus, is a small, uniform crushed rock product designed for applications where a finer, smoother finish is required...
