- Thermal analysis -
Studies the physicochemical transformations materials undergo as a response to thermal variations.
dating
morphology
technology
origin
composition
alteration
Ceramic
Glass
Mortar
Ceramic Building Materials (CBM) & Glass
DTA/TGA can determine the mineral components of ceramic building material and historic glass, depending on the temperature at which their thermal transformations
occur, as well as identify the presence of organic material in the clay or glass matrix.
From the mineral composition it is possible to estimate the firing temperature of a ceramic object (Naseerutheen et al., 2013) which can indicate the manufacturing
period and production technique and can be useful for provenance studies.
Mortar & Plaster
Thermal analysis on historical mortars and plasters allows identifying and quantifying the minerals contained thereby determining the mortar type.
Divergences in the decomposition temperature of a sample can indicate the presence of soluble salts.
The hydraulic nature of mixtures can be evaluated measuring a sample’s weight loss temperature range due to dehydration and due to the decomposition of carbonates by means of DSC/TG.
TA spectrum. Image by Nora Pérez Castellanos
Thermal analysis is the general term that refers to the study of the physical and chemical transformations that organic and inorganic materials undergo in response to changes in their temperature. These transformations indicate the nature of the components the material of interest consists of. Thermo-analytical (TA) techniques are very suitable for characterizing mainly ancient mortars and ceramic building materials, as they detect the main components and the nature of their aggregates with minimum sample quantity. TA techniques for building materials include:
Simultaneous Thermal Analysis (STA), instead, refers to the simultaneous application of TGA and DSC on the same material.
accuracy
time
cost
in situ
invasive
destructive
When heating a specimen, different physicochemical transformations occur within it, like melting, crystallization, dehydration/evaporation, fusion, dehydroxylation*, decomposition, etc. These transformations associated with the temperature range at which they happen, provide an insight on the components the specimen is made of (Genestar & Pons, 2003). From all following thermo-analytical methods*, diagrams called Thermograms are obtained, on which result interpretation is based. DTA and DSC consist in the comparison of these graphs to reference ones.
