There are 10 parts to the standard. Broadly, half cover the treatment of processed aggregates complying with the BSEN 13242 for aggregates and the other half, the treatment of soils. For each, a wide spread of hydraulic binders or hydraulic combinations is covered; for example there is a part that covers the treatment of aggregate with fly ash (or more accurately a combination of fly ash with either lime or cement but with fly ash the main constituent of the binder) and a part that covers soil treated by fly ash. There are corresponding parts covering cement, lime, GBS and materials specifically called hydraulic road binders (HRB). HRB are factory-produced hydraulic binders specially formulated for road use. Typically they are blends of GBS and or fly ash with lime and gypsum or cement. They are extensively in continental Europe.

EN 14227. Hydraulically bound mixtures – Specifications

• Part 1: Cement bound granular mixtures (CBGM).
• Part 2: Slag bound mixtures (SBM).
• Part 3: Fly ash bound mixtures (FABM).
• Part 4: Fly ash for hydraulically bound mixtures.
• Part 5: Hydraulic road binder bound mixtures (HRBBM).
• Part 10: Soil treated by cement (SC).
• Part 11: Soil treated by lime (SL).
• Part 12: Soil treated by slag (SS).
• Part 13: Soil treated by hydraulic road binder (SHRB).
• Part 14: Soil treated by fly ash (SFA).

In the UK, each part can be obtained as a BSEN from the
BRITISH STANDARDS INSTITUTION, Chiswick, London.

Whatever the hydraulic binder or combination and whether aggregate or soil, the scope of each part of BSEN14227 is the same, covering:

• permitted constituents,
• permitted mixture types (distinguished by aggregate type),
• laboratory mechanical performance classification.

It should be noted that the standard does not address production or construction issues or application. These issues are considered the responsibility of individual nations, the rationale being that the mixtures are products for users to apply for their own situation.

With regard to laboratory mechanical performance classification, the choice is also deliberately wide, to cover all European practice and needs for pavements. Performance can be specified by CBR, compressive strength or the combination of tensile strength and elastic stiffness, for any pavement layer and traffic application.