Scaled-up commercial production of reactive magnesia cement pressed masonry units. Part II: Performance

Reactive magnesia cements have recently emerged as a potentially more sustainable and technically superior alternative to Portland cement as they set by absorbing carbon dioxide and as a result gain significant strength. This two-part publication investigates the application of reactive magnesia alone as the cement component in pressed masonry units and compares it to those containing Portland cement. Laboratory-scale production optimisation was performed followed by a scaled-up commercial production at the Forticrete plant in Dewsbury, West Yorkshire, UK. A range of aggregates were used in the blocks including natural aggregates, Lytag, an ash mix and a limestone mix. This paper, the second of a two-part publication, assesses the performance of the commercial blocks both in terms of strength and also microstructure and compares them with their corresponding laboratory samples. The compressive strength values reached by all the reactive magnesia blocks were higher, in some cases much higher, than those of their corresponding Portland cement blocks, highlighting the significant advantages of the former, the microstructure confirming that this is due to carbonation, by carbon dioxide sequestration, which was quantified as having been achieved to significant levels.