Low energy pre-blended mortars: Part 2 – Production and characterisation of mortars using a novel lime drying technique

• A lime-drying process is used to remove excess water from 2 mortar types.
• Process successfully applied to Formulate Lime and Roman cement mortars.
• Optimally dried mortars do not degrade during storage up to 10 weeks.
• Calcite content within hydrated lime phase may increase strength of some mortars.

The presence of free water in mortars destined for silo or bagged storage can lead to the degradation of the binder phase. Such water may be present as a result of using wet, as-delivered sand or as a consequence of prior processes such as de-activation of Roman cement. Thus, water must be removed from the system prior to storage. Part 1 of this paper describes the control of a technique by which quicklime is added to the wet system which principally dries it by both slaking the quicklime and evaporation as a consequence of the exothermic slaking reaction. Two examples of mortars are presented in which excess water is removed from the system by the inclusion of quicklime. In the first, the water is present in the as-delivered sand and the binder is a combination of the slaked lime and ggbs. In the second, the water remains after pre-hydration of a Roman cement which is a process to retard its rapid setting characteristics. It is shown that optimally dried mortars are not subject to degradation following storage of both mortar types.