Despite how these two products look when in a stockpile they are, in fact, very different.
Type 1 material is graded from 40mm down to dust and is used for a regulating course under highways, sometimes referred to as sub-base.
Type 1 stone is made to ‘Clause 803: The Specification for Highway Works’ and is graded to comply with certain particle sizes and a frost susceptibility rating. The frost susceptibility rating is often why some softer limestones are unable to meet the specification.
Where some quarries cannot comply with the MOT Type 1 specification, they offer a product called DOT Type 1. It is important to note that there is no specification for DOT Type 1 so whilst it may comply with the Clause 803 grading for particle size, it is likely it will not comply with the frost susceptibility rating and therefore would not be suitable for major infrastructure works.
Crusher Run, on the other hand, can be graded to various sizes but most commonly is offered in 75mm – dust or 40mm – dust.
There is no specification for crusher run and therefore it differs from Type 1 in both particle size and frost susceptibility. Where the crusher run is produced in a quarry that also produces a fully graded Clause 803 Type 1 it is likely the frost susceptibility will be compliant with highway standards, however, the particle size will be very different. Crusher Runs often have a much higher percentage of the smaller particle sizes (higher fines content).
Crusher Run is normally used as a sub-base for domestic applications, as when compacted it makes an extremely solid and level base for patios, garden buildings and flooring.