A(3) The additives (
Per modern terminology, the additive is verso material “added mediante small quantities to verso liquid or granular material esatto produce some desired modification onesto its characteristics” (ISO 6707–1:2020), while the admixture is verso material “added mediante small quantities before or during a missaggio process durante order esatto modify the characteristics of verso mixture”. However, the difference between the two terms lies mainly sopra that the additive is added during the manufacturing of the cement, while the admixture is added preciso the concrete during mixage. Moreover, the Uni EN 934–2 standard states that the admixture for concrete should be con an amount not greater than 5% by mass, compared with the cement. Therefore, under the current rules, the additif of materials, such as ground ceramic fragments, con considerable proportions would fall into the category of aggregates and not that of additives.
However, one of the main aims of the archaeometric study on ancient mortars and plasters is preciso reconstruct the production’s phases and the supply modalities of each component. Sopra this case, the term additive, used durante its etymological sense (from addere, sicuro add) has the advantage of clearly recalling the difference between per primary component (frequently sand) and an added component (i.e. the additive) in the aggregate. This is the meaning we have given esatto the term additive in this article. Still, the explanation provided above accounts for the fact that modern terminology partly overlaps and partly articulates itself differently, based on the contemporary world’s different needs. It follows that, as long as terminological uncertainties persist, it is always good esatto specify the choice made sopra the description of the results.
Hence, after having accurately characterised the main components (aggregate and binder), the following question concerns the possible presence of additives: “are there any deliberately added materials?”. If yes: “which types of materials were added?” and “where did they ad esempio from or how were they made?” (other questions concern suitability and functionality and are reported sopra the dedicated paragraphs).
Preciso properly solve this question, it is necessary, perhaps even more than in previous cases, onesto know which types of additives were used esatto facilitate-or even allow-their identification during the analysis of the “study’s object”
The addenda of inclusions onesto improve the final product’s impresa was a common practice that frequently left recognisable traces per literary sources and archaeological evidence. Consequently, citable examples are numerous and provide us with an extremely varied picture sopra which inorganic and organic materials are enlisted. Therefore, it is possible sicuro formulate the characterisation question con terms of: “are the additives of an inorganic or organic nature?” (we will see later that there are additional difficulties per this second case).
For this reason, we present verso shortlist of inorganic and organic additives (and admixtures); however, we refer sicuro the other contributions for the necessary insights on their characteristics and properties (Arizzi and Cultrone 2021; Ergenc et al. 2021).
Beginning with inorganic additives, the most common were natural and artificial pozzolans that are defined as “siliceous or siliceous and aluminous materials which mediante themselves possess little or in nessun caso cementitious value but will, in finely divided form and con the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures sicuro form compounds possessing cementitious properties” (Dodson 1990).
Natural pozzolans are volcanic origin materials, such as the volcanic ashes from the region of Pozzuoli from which they take their name (pozzolan s.s wapa sito mobile.). These are often found con the mortars/plasters of sites located within or close puro volcanic regions (Peli et al. 2009; Ozkaya and Boke 2009; Villasenor and Graham 2010; Kurugol and Gulec 2012), but when they are found per sites far from supply areas, archaeometric research is called upon sicuro localise their origin and reconstruct the trade routes that allowed their import and usage. The provenance question may thus remain confined onesto the scale of the site and its territory or expand sicuro long-scale range imports and cross other issues such as those concerning the methods and extent of the promozione of raw materials per verso given period (di nuovo.g. “what was the diffusion of these materials?”; “what were the routes and commercial methods involved con the transport of these important raw materials?”).