RILEM TC 277-LHS report: How hot are hot-lime-mixed mortars? A review

Abstract It is believed that many historic mortars were made using hot-lime mixing techniques. They are back in use today, and their good qualities often praised, including being more compatible a better match with fabrics. This paper studies the methods of producing putties. discusses variables determine properties resultant such as slaking calcination, compares equivalent putties, factory-produced calcium lime hydraulic mortars. The concludes most important variable governs mixed quantity water used for slaking, because it determines temperature reached during which makes Ca(OH) 2 vary from fairly large size to extremely small, hence different properties. Based on scientific evidence, concluded best method dry-slaking (sand-slaking) long storage, combines high (that reduces particle increases surface area hydrate), gradual lowers volume expansion crack development) storage (to ensure complete no cracks). Many probably mixed. However, practically impossible recreate them today due limestones, kilns, calcination regimes slaking/storage past. Hydraulic magnesian quicklimes historically hot-mixing. In contrast, factory purer limes higher free content greater reactivity. Therefore, mix quicklime may not be authentic or than natural –NHL– mortar designed suit specific fabric application. To quality can consistently repeated, specification should contain both process materials including: type (dry/wet); amount used; details time at takes place; what stage does occur. control temperature, right established (according content) by trial will also inform yield allow proportioning. With careful site work specification, high-quality, NHLs mixing. However requires logistics, closer care complicated specification.