The two terms describe apparently similar materials that, added per small quantities, can modify the properties of the starting mixture
A(3) The additives (
Con modern terminology, the additive is per material “added con small quantities onesto a liquid or granular material sicuro produce some desired modification onesto its characteristics” (ISO 6707–1:2020), while the admixture is a material “added in small quantities before or during per mixing process in order sicuro 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 esatto the concrete during mixing. Moreover, the Accouple EN 934–2 norma states that the admixture for concrete should be durante an amount not greater than 5% by mass, compared with the cement. Therefore, under the current rules, the addenda 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 to reconstruct the production’s phases and the supply modalities of each component. Sopra this case, the term additive, used sopra its etymological sense (from addere, to add) has the advantage of clearly recalling the difference between per primary component (frequently sand) and an added component (i.addirittura. the additive) mediante the aggregate. This is the meaning we have given to the term additive mediante 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).
Preciso properly solve this question, it is necessary, perhaps even more than durante previous cases, to know which types of additives were used puro facilitate-or even allow-their identification during the analysis of the “study’s object”
The addenda of inclusions puro improve the final product’s esibizione was a common practice that frequently left recognisable traces durante literary sources and archaeological evidence. Consequently coupon ilove, citable examples are numerous and provide us with an extremely varied picture durante which inorganic and organic materials are enlisted. Therefore, it is possible onesto formulate the characterisation question per terms of: “are the additives of an inorganic or organic nature?” (we will see later that there are additional difficulties durante this second case).
For this reason, we present per shortlist of inorganic and organic additives (and admixtures); however, we refer puro 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 per themselves possess little or in nessun caso cementitious value but will, per 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.). These are often found durante the mortars/plasters of sites located within or close preciso volcanic regions (Barba 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 esatto localise their origin and reconstruct the trade routes that allowed their import and usage. The provenance question may thus remain confined preciso the scale of the site and its territory or expand preciso long-scale range imports and ciclocampestre other issues such as those concerning the methods and extent of the commercializzazione of raw materials durante a given period (addirittura.g. “what was the diffusion of these materials?”; “what were the routes and commercial methods involved durante the transport of these important raw materials?”).
