Multi-analytical approach for chemical-mineralogical characterization of reaction rims in the lime mortars from Amaiur Castle (Navarre, Spain)

Petrographic and Chemical–Mineralogical Characterization of Mortars from the Cistern at Amaiur Castle (Navarre, Spain)

“…The M-S-H phases show a layered structure and have been related to poorly crystalline phyllosilicates [64,[66][67][68][69]. The reaction zone of the dolomitic aggregates of the structural mortars from Amaiur Castle showed the presence of M-S-H phases, which are suggested as a result of an ASSR, although the presence of the M-S-H phases could not be confirmed [23]. According to Mackenzie and Bowden [37], amesite is formed by the substitution of the Si 4+ in the tetrahedral layers and the Mg 2+ in the octahedral layers by the Al 3+ .…”

“…The cistern tank is shown in green, the vault lunette is shown in blue, the barrel vault is shown in yellow, and the 14th-15th centuries wall is shown in black. Furthermore, the reaction zones observed in dolomitic aggregates resulted from the dedolomitization of dolomitic aggregates, and the presence of hydrotalcite in the binder has been related to the use of the traditional hot-mixing method in mortar manufacture [23]. In the manufacture of cistern tank mortars, the use of this traditional hot-mixing method would also be expected since reaction zones were not only observed at the edge of the dolomitic aggregates, but they also stand out in the ceramic fragments and some silico-aluminous aggregates (Figure 4a-d).…”

“…Hydrotalcite has been identified in all analysed mortar binders ( Figure 5). Magnesium released from the dedolomitization process, leading to the formation of the reaction zone in the edge of dolomitic aggregates, and the aluminium released from the breakdown of phyllosilicates favours the formation of hydrotalcite [23,[56][57][58]. Nevertheless, some amount of magnesium and aluminium can also come from the lime used for the mortar manufacture when impure limestones or partially dolomitized limestones have been used as the raw material for lime production [28,59].…”

Alkali-dolomite reaction in air lime mortar – implications for increased strength and water resistance

“…This work aims to clarify the understanding of progressive ACRs and their influence on altered water resistance and mechanical strength, which are the two main issues in restoration and conservation. To the best of our knowledge, detailed phenomenological description of the ACRs is something new, is not found in the majority of published papers [25,36,37], and suggests that the dissolution/reprecipitation cycle of CaCO3 is the main cause of the observed improvement of mechanical strength and water resistance of aged lime mortars.…”