Type 1 Aggregates
(3 Products)Type 1 aggregates are the most widely used approved sub-base in the construction sector. Typically made up of crushed rock, gravel, or recycled concrete, they are used as a base layer for roads, paths, and buildings. Type 1 aggregates are typically characterised by their large particle size and angular shape, which endows them with impressive compaction properties and a high load-bearing capacity. They also make for an effective bulk filling and levelling material.
Understanding MOT Type 1 Aggregates
MOT Type 1 is a crushed aggregate specified by the Ministry of Transport (MOT) for use in creating a stable sub-base for high-traffic areas. Composed of a graded mix of stones ranging from 40mm down to dust, the various particle sizes work together to interlock during compaction. This process eliminates voids, creating a dense foundation that can support significant weight without shifting or settling.
The primary function of this material is to distribute loads evenly across the underlying ground, preventing the sinking or cracking of the top layer, whether that be asphalt, concrete, or block paving. Because it provides a frost-resistant and durable platform, it is the standard requirement for any project where structural longevity and weight-bearing capacity are non-negotiable.
Material Range
- MOT Type 1 Bulk Solutions: Large-scale supply options for major groundworks, featuring formats such as 800kg Bulk Bags and Loose Load delivery by the tonne (minimum 5-tonne order).
- Pre-Packed MOT Type 1: Convenient, smaller volumes for restricted access or minor repairs, including the 25kg bags for easy manual handling and precise application.
Performance Benefits
- High Load-Bearing Capacity: Specifically graded to support heavy vehicular traffic and structural foundations.
- Excellent Compaction: The mix of large and fine particles ensures a solid, interlocking finish when used with a vibrating plate or roller.
- Standard Compliance: Manufactured to meet the requirements of the Department of Transport Specification for Highway Works, Clause 803.
- Exceptional Durability: Resistant to moisture and frost, ensuring the sub-base remains stable throughout seasonal weather changes.
Typical Applications
- Driveway Foundations: Providing the essential base layer for block paving, gravel, or resin-bound drives.
- Highway Construction: Used as a sub-base for roads and pavements to ensure long-term structural stability.
- Hardstanding Areas: Creating solid foundations for sheds, outbuildings, or heavy machinery platforms.
- Patio Sub-bases: Ensuring a level and movement-free surface for natural stone or porcelain paving slabs.
Specification & Standards
- MOT Clause 803: The specific UK standard for the grading and composition of Type 1 sub-base materials.
- BS EN 13242: Aggregates for unbound and hydraulically bound materials for use in civil engineering work.
Related Materials and Construction Uses
MOT Type 1 is typically the secondary layer in a construction buildup, installed directly over a geotextile membrane to prevent the aggregate from mixing with the soft subsoil.
This separation is vital for maintaining the integrity of the sub-base over time and ensuring the drainage properties of the sub-grade are not compromised.
Once the Type 1 layer is fully compacted, it provides a stable, level surface for various bedding materials found within our wider range of sand and aggregates, such as coarse-graded sharp sand for paving or building sand for mortar mixes.
In drainage-heavy applications, it may be used in conjunction with other permeable aggregates, though its primary role remains the provision of a rigid, non-yielding platform for the final decorative or functional surface finish.
Frequently Asked Type 1 Aggregates Questions
What Is The Difference between Type 1 and Type 2 Aggregate?
Type 1 and Type 2 aggregate are different classifications of construction aggregate.
Type 1 aggregate, also known as "DTp1" or "DTp Type 1," is a granular material that is typically made from crushed rock, such as limestone, granite, or gritstone. It is typically used in road construction and other transport infrastructure, also serving as a sturdy sub-base layer for building foundations.
Type 2 aggregate is a material that is typically made from crushed rock, but is of a lower quality than Type 1. Type 1 aggregate is considered to be of higher quality, and is used for more critical applications, while Type 2 aggregate is finer and has a higher dust content.
What Are The Primary Aggregates Used in MOT Type 1?
- Limestone
- Granite
- Sandstone
Which Recycled Aggregates Are Used in MOT Type 1?
- Crushed Concrete
- Crushed Glass
- Selected other aggregates (generally brick, ceramic, etc.)
What Are Scalpings?
Scalpings are more or less quarry waste. These small stone offcuts are removed during the screening process for larger, higher-quality rocks.
Despite the negative connotation of being labelled as "waste," scalpings are incredibly useful for levelling out foundations due to their durability, versatility, and abundance.
Is Type 1 Good For Drainage?
While MOT Type 1 is a great sub-base material offering many benefits, it has a minor drawback in that it is not a permeable sub base material. This means that water will not pass through it easily and, if it does, it will take a much longer time to filter through. Alternatives such as granite or limestone, however, offer much better drainage properties as sub bases.
Related Articles
Garden and Landscaping: A Technical Blueprint for Outdoor Projects
How to Compact MOT Type 1
How to Lay a Patio On Soil
How To Lay Block Paving
How To Lay A Patio
How To Build A Decking
