The two terms describe apparently similar materials that, added durante small quantities, can modify the properties of the starting mixture
A(3) The additives (
Per modern terminology, the additive is per material “added per small quantities puro per liquid or granular material puro produce some desired modification onesto its characteristics” (ISO 6707–1:2020), while the admixture is verso material “added con small quantities before or during a mixage process mediante order esatto modify the characteristics of a mixture”. However, the difference between the two terms lies mainly in that the additive is added during the manufacturing of the cement, while the admixture is added to the concrete during missaggio. Moreover, the Adherent 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 sicuro reconstruct the production’s phases and the supply modalities of each component. Con this case, the term additive, used con its etymological sense (from addere, onesto add) has the advantage of clearly recalling the difference between per primary component (frequently sand) and an added component (i.di nuovo. the additive) in the aggregate. This is the meaning we have given sicuro the term additive con 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 onesto specify the choice made mediante 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 quale from or how were they made?” (other questions concern suitability and functionality and are reported in the dedicated paragraphs).
Onesto properly solve this question, it is necessary, perhaps even more than sopra previous cases, puro know which types of additives were used preciso facilitate-or even allow-their identification during the analysis of the “study’s object”
The prime of inclusions to improve the final product’s successo was per common practice that frequently left recognisable traces mediante literary sources and archaeological evidence. Consequently, citable examples are numerous and provide us with an extremely varied picture per which inorganic and organic materials are enlisted. Therefore, it is possible preciso 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 in this second case).
For this reason, we present verso shortlist of inorganic and organic additives (and admixtures); however, we refer to 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 sopra themselves possess little or mai cementitious value but will, mediante finely divided form and durante the presence of moisture, chemically react with calcium hydroxide at ordinary temperatures esatto 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 con the mortars/plasters of sites located within or close onesto volcanic regions (Pizzo et al. 2009; Ozkaya and Boke 2009; Villasenor and Graham 2010; Kurugol and Gulec 2012), but when they are found durante sites far from supply areas, archaeometric research is called upon puro 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 to long-scale range profilo elite singles imports and cross other issues such as those concerning the methods and extent of the promozione of raw materials mediante verso given period (ed.g. “what was the diffusion of these materials?”; “what were the routes and commercial methods involved per the transport of these important raw materials?”).