B2是BUILDING CODE里面的Durability
3.1 Concrete
3.1.1 NZS 3101: Part 1 Section 3 is an acceptable solution for meeting the durability requirements of concrete building elements subject to the following modification: Provisions in this Standard that are in nonspecific or unquantified terms do not form part of the Acceptable Solution. Non-specific or unquantified terms include, but are not limited to, special studies, manufacturer’s advice and references to methods that are appropriate, adequate, suitable, relevant, satisfactory, acceptable, applicable, or the like. Such provisions must be treated as the basis of an alternative solution proposal.
详细上http://www.dbh.govt.nz/building- ... documents-downloads