A(3) The additives (
In modern terminology, the additive is verso material “added per small quantities esatto per liquid or granular material esatto produce some desired modification sicuro its characteristics” (ISO 6707–1:2020), while the admixture is verso material “added in small quantities before or during per missaggio process durante order esatto modify the characteristics of per mixture”. However, the difference between the two terms lies mainly per that the additive is added during the manufacturing of the cement, while the admixture is added puro the concrete during mixing. Moreover, the Uni EN 934–2 canone states that the admixture for concrete should be sopra an amount not greater than 5% by mass, compared with the cement. Therefore, under the current rules, the addition of materials, such as ground ceramic fragments, durante 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 puro reconstruct the production’s phases and the supply modalities of each component. Con this case, the term additive, used per its etymological sense (from addere, esatto add) has the advantage of clearly recalling the difference between per primary component (frequently sand) and an added component (i.ancora. the additive) mediante the aggregate. This is the meaning we have given esatto the term additive mediante this hitwe 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 in 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 che tipo di from or how were they made?” (other questions concern suitability and functionality and are reported in the dedicated paragraphs).
Puro properly solve this question, it is necessary, perhaps even more than mediante previous cases, puro know which types of additives were used sicuro facilitate-or even allow-their identification during the analysis of the “study’s object”
The prime of inclusions preciso improve the final product’s impresa was per common practice that frequently left recognisable traces durante literary sources and archaeological evidence. Consequently, citable examples are numerous and provide us with an extremely varied picture con which inorganic and organic materials are enlisted. Therefore, it is possible esatto formulate the characterisation question sopra 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 esatto 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 per niente cementitious value but will, sopra finely divided form and mediante the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures to 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.). These are often found in the mortars/plasters of sites located within or close to volcanic regions (Pizzo et al. 2009; Ozkaya and Boke 2009; Villasenor and Graham 2010; Kurugol and Gulec 2012), but when they are found in sites far from supply areas, archaeometric research is called upon esatto localise their origin and reconstruct the trade routes that allowed their import and usage. The provenance question may thus remain confined sicuro the scale of the site and its territory or expand puro long-scale range imports and ciclocross other issues such as those concerning the methods and extent of the commercializzazione of raw materials con a given period (e.g. “what was the diffusion of these materials?”; “what were the routes and commercial methods involved per the transport of these important raw materials?”).