What Is GRAVITE®?
GRAVITE® is a cement‑bound granular material designed to function as a structural pavement layer. Unlike unbound sub-base, where performance relies largely on compaction and confinement, GRAVITE gains strength through cementitious binding, forming a stiff, load‑spreading layer within the pavement structure.
It is manufactured under controlled conditions to deliver consistent grading, predictable strength development, and compliance with UK highway specifications.
Unbound Sub-base vs Hydraulically Bound Sub-base: What’s the Difference?
Traditional unbound sub-base materials consist of graded aggregates compacted in layers. While widely used, they remain susceptible to deformation, moisture ingress, and long‑term performance variability.
GRAVITE differs in several key ways:
- It develops structural strength through cement hydration
- It distributes loads more effectively across the pavement
- It is less sensitive to water and frost action
- It performs predictably over its service life
These differences have a direct impact on pavement design, durability, and maintenance requirements.
Improved Load‑Bearing Capacity and Structural Performance
Because GRAVITE is hydraulically bound, it delivers significantly higher compressive and flexural strength than unbound sub-base materials. This allows:
- Better distribution of traffic loads to underlying layers
- Reduced risk of rutting and permanent deformation
- Suitability for heavily trafficked roads, airfields, and industrial areas
For engineers, this means greater confidence in long‑term structural performance.
Thinner Pavement Designs and Reduced Material Use
The higher stiffness and modulus of GRAVITE enable thinner pavement constructions compared with unbound alternatives. This can result in:
- Reduced excavation depths
- Lower material volumes
- Whole‑life cost efficiencies
These benefits are particularly valuable on urban, constrained, or brownfield sites where excavation depth and disposal costs are critical considerations.
Durability, Water Resistance, and Frost Performance
Unbound subbase materials are inherently permeable, making them vulnerable to water‑related deterioration such as pumping, erosion, and frost heave.
GRAVITE’s hydraulically bound structure offers:
- Lower permeability
- Improved resistance to moisture ingress
- Enhanced frost durability
- Reduced maintenance over the pavement lifecycle
This contributes to longer service life and improved asset performance.
A More Sustainable Sub-base Solution
GRAVITE incorporates Incinerator Bottom Ash Aggregate (IBAA), reducing reliance on quarried aggregates and supporting more sustainable construction practices.
Sustainability benefits include:
- Reduced use of primary resources
- Lower environmental impact
- Potential contribution towards BREEAM and sustainability objectives
- Fully recyclable at end of life
This allows performance and sustainability to be addressed simultaneously.
Compliance with UK Highway Specifications
GRAVITE is manufactured in accordance with recognised UK standards, including:
- Series 800 of the Specification for Highway Works (SHW) / MCHW update to CC201
- BS EN 14227‑1 for Cement Bound Granular Mixtures
This ensures quality, consistency, traceability, and confidence for designers, contractors, and asset owners.
Faster Construction and Programme Efficiency
GRAVITE develops strength rapidly, enabling earlier trafficking and shorter construction programmes. This supports:
- Reduced road closures and traffic disruption
- Improved efficiency on phased construction projects
- Greater certainty on time‑critical schemes
Early strength gain is a key advantage where programme certainty is essential
When Is GRAVITE the Right Choice?
GRAVITE is particularly well suited to:
- Highway and local authority road schemes
- Commercial and industrial developments
- Infrastructure projects with high traffic loading
- Sites requiring reduced pavement thickness or improved durability
Its performance characteristics make it a practical alternative to traditional unbound sub-base in many modern pavement designs
Summary: Why Specify GRAVITE?
GRAVITE offers clear advantages over traditional unbound sub-base materials, including improved strength, durability, sustainability, and whole‑life value. As infrastructure demands continue to increase, hydraulically bound sub-base solutions such as GRAVITE provide a robust and future‑ready foundation.
For technical guidance or project‑specific advice, contact us today.
