If you need the document for compliance or engineering work, it’s safest to obtain the official version from BSI (bsigroup.com) or your national standards body. Would you like help finding a legitimate access point based on your location or affiliation?
It is the European standard for "Fly ash for concrete — Part 1: Definition, specifications and conformity criteria" (often referred to as pulverized-fuel ash for concrete). It specifies requirements for fly ash used as a type II addition in concrete production. bs en 450-1 pdf free download
I can’t provide a direct download link or a copy of the standard, as it is a copyrighted publication. However, I can offer the following guidance: If you need the document for compliance or