Thermal and Petrographic Characterization of Herculaneum Wall Plasters

Abstract

Roman plasters sampled from different houses at the archaeological site of Herculaneum, Italy, (2010–12) were studied by means of petrography, thermal analysis and X‐ray fluorescence. Herculaneum plasters are composed by preparatory layers (arriccio) with a thickness of several centimetres and are based on a calcitic binder and volcanic scoriae as aggregates, covered by a thin final layer characterized by a low granulometry. Most of the sampled plasters can be placed into two groups based on the aggregate composition and classified as marmorino or intonachino. However, a similar aggregate composition did not induce superimposable thermal behaviour, thus suggesting that the samples underwent different ageing/weathering processes, with a consequent change of the ratio among the components.

A re-evaluation of manner of death at Roman Herculaneum following the AD 79 eruption of Vesuvius

“…Caricchi et al . 2014; Leone et al 2016). Their estimates (240–370°C) may suggest an even lower exposure temperature, assuming that it could indeed apply to the beach and fornici areas, as well as within the town itself.…”

“…Others have investigated the exposure of mortars, plasters and wood to the pyroclastic temperatures at different parts of the site (e.g. Caricchi et al 2014;Leone et al 2016).…”

Microbial biofilm community structure and composition on the lithic substrates of Herculaneum Suburban Baths

“…substrates: plaster in the Vestibulum, polychrome marble in the Tepidarium, and mortar in the swimming pool. Both plaster and mortar are non-homogeneous materials widely diffused in Herculaneum buildings: the former is made by a mixture of calcitic binder and volcanic scoriae, covered by a thin superficial layer of lime and marble powder [15], whereas the latter is prevalently composed by lime and inert volcanic aggregates with variable dimensions [16]. The general distribution of biofilms on the walls of the Suburban Thermae appeared patchy to the naked eye.…”

Ineducable us: the applications and contexts of microscopy used for the characterisation of historic building materials

“…Mortars are complex man-made materials, that can defy straightforward classification due to the variability of their components, originating from local and highly contingent material sources and non-standardised construction and manufacturing practices. The ability of microscopy to facilitate the description of characteristics in a material, that relate to human agency and practical material choices, mean that it is very valuable in support of archaeological investigations, of mortars [34,35] and but also of other ceramic materials, such as pottery and bricks [36].…”

“…The texture of the protolith can remain as a pseudomorph of the original texture [32] allowing matching with source. This is enhanced where unburnt cores within grains preserve original carbonate lithology, permitting elemental analysis on the microscale with EDS, and potentially other techniques, such as FTIR microscopy [40], and also thermal analysis to understand the composition of archaeological lime based materials [35].…”