Concrete properties after partly cement and sand replacement with wood ash – investigation of the influence of wood ash on the compressive strength

This thesis is focused on a wood ash from Verdo’s kraftvarmevark, Randers. The ash has a rather high loss on ignition of almost 14%. The ash is pretreated in different ways before tested as cement or sand replacement in test mortar specimens: milling, ignition (to remove the organic fraction) and a combination of these two. Milling the ash did not have a significant impact on the compressive strength of the mortar, probably because the ash prior to milling had a very fine grained structure. Ignition of the ash prior to use significantly reduced the compressive strength compared to the reference, and ignition followed by milling gave even lower compressive strength of the cast mortar.

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