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Frost heave susceptibility

Frost susceptible material is deemed to be material with a mean heave greater than 15 mm when tested in accordance with BS 812-124 (as amended by MCHW Clause 801.8).
Where frost susceptible materials exist within 450 mm of the surface, such materials may be reinstated to the same levels but, generally, frost susceptible material must not be used within 450 mm of a road surface. However, 300 mm of wholly bituminous material is considered to provide adequate insulation and may be used as an alternative.
In the event of prior notification by the authority, where the existing depth of non-frost susceptible materials is more than 450 mm below the road surface and the authority requires such a thickness of non-frost susceptible material to be maintained, only non-frost susceptible materials can be used for the relevant depth.
All frost heave susceptibility testing must be carried out by a laboratory holding current UKAS accreditation for the specified method of testing, unless otherwise agreed.