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Mineralthermometrie an anthropogenen pyrometamorphen Umwandlungsprodukten in hochgebrannten Gipsmörteln
Projektleitung
	Dr. rer. nat. Thomas Schmid BAM - 1.4 Prozessanalytik E-Mail: Thomas.Schmid@bam.de
Förderstruktur
	DFG - DFG - Sachbeihilfen
Projektbeginn
	01.10.2021
Projektende
	30.09.2024
Projektart
	Realisierte Antragsforschung
Themen-/Aktivitätsfeld
	THEMENFELD Analytical Sciences, * Zerstörungsfreie Prüfung und Spektroskopie
Abstract
	The proposed project aims to establish systematic workflows for the identification and charac-terisation of mineral indicators revealing processing conditions of mortar binders – with calcina-tion temperatures as central parameter –, and to provide a spectral library and guidelines for the application of such mineral thermometers. Reactivity, strength and durability of mortar binders are strongly affected by the calcination temperature, precisely because the conservation of our cultural heritage with adequate restoration mortars requires the identification and deep under-standing of ancient building materials. The contemporary technological know-how is preserved in our built heritage. In many cases, only modern analytical methods enable the re-enactment of lost or unknown historical production recipes and can provide evidences for the elucidation of historical distribution pathways of technological know-how. Thus, the project is expected to have high impact in fields including (art) history, art technology, and conservation-restoration. Novel facts about architectural heritage can generate social impact in fields like local cultural policy and tourism. The project has also the potential to trigger scientific developments regarding related material systems of our times (e.g., the first quantitative discrimination of the  and  forms of plaster of Paris is as a side-product of our preliminary research on medieval high-fired gypsum[43]). It is also expected to support the re-enactment of historical materials offering par-ticular physical-chemical properties. Examples of high-fired medieval gypsum remained intact over centuries, even if exposed to weathering, due to higher strength and durability than the low-burnt hemihydrate gypsum (plaster of Paris) of our times. Modern high-fired Estrichgips might also differ from historical counterparts, because of the heterogeneous temperature distri-butions in ancient kilns suggested by modern research,[32-39] [42, 51] or due to the use of additives like alum (see section 1.1d).[58] Ziegelei Hundisburg has commercialised re-enacted historical anhydrite-based binders, which will be involved in the proposed project. Scientific proofs for different properties are expected to affect the visibility and application of such products. The gypsum–anhydrite system will be studied also because of recently increasing interest ranging from basic insights to applications in building materials,[43] including gypsum as starting material of alternative cement clinker production through routes with dramatically reduced CO2 emis-sions.[24, 83] Recent publications also concern the study of gypsum phase conversions for the interpretation of data acquired on Mars.[84] The results are expected to be broadly applicable due to overlap between, for example, gypsum mortars, lime, cement, slag, ceramics and natural building stones regarding indicator minerals (see section 1.1b) and because of the broadly ap-plicable workflows for their characterisation aimed to be developed. Potential applications of mineral thermometers also include additive manufacturing involving ceramic processes and stability assessments of building stones after fire events.[4] Beyond mineral thermometry, the projected spectral library connecting Raman reference spectra with mineral types and chemical compositions will be applicable in the geochemical dating and provenancing of rocks and materials, soil analyses, forensic, geological and planetary studies.