GRAVEL LIME ? Research into Danube gravel as the main ingredient of the historic mortars at the castle Prandegg in Upper Austria (original) (raw)
Related papers
Proceedings of the 5th Historic Mortars Conference, 2019
The Benedictine convent of St. John at Müstair (UNESCO world heritage site) in Grisons, Switzerland, preserves a huge amount of well-documented (dolomitic) archaeological mortar samples dated from the Carolingian to the Baroque Age (8 th to 18 th century). In the medieval period, the architecture of the Val Müstair and the surrounding regions was characterized by stone and mortar constructions. The geological overview of the area around the monastery indicates that dolomitic rocks are widely available and the production of lime was a common practice in the Müstair valley as demonstrated by the presence of mortar mixers, lime-kilns and local toponyms. As part of an ongoing research project, the question about the potential source(s) of the raw materials for the production of the binder of the historic mortars was posed. The proposed research is based on the close relationship between the geological raw materials and the underburnt relics (lime lumps) found in the archaeological mortars. Textural features and mineralogical composition were investigated by combining Polarizing Light Microscopy (PLM) and X-ray Powder Diffraction (XRPD) analysis. Results indicate that the textural evidence (sometimes) retained by underburnt relics of dolomitic rocks cannot be used as possible criteria for provenance studies due to the high variability of dolomite crystal size, fabric and heterogeneity within the same group and at the scale of individual samples. However, the presence of silicate phases may suggest potential proxies.
Research project on ancient and contemporary lime mortars in the walloon region (Belgium)
These studies should improve our restoration habits, which could be usefully re-oriented in order to improve practices on the restoration sites and ensure the permanence of our monuments. The main aim is to understand better the short-, medium-, and long-term behaviour of lime mortars. Some 100 formulations have been developed for laboratory testing according to various standards. A dozen "basic recipes" that should enable us to determine the main differences in their mechanical behaviour according to their composition were subjected to the standardised tests first. Taking these formulae as our starting points, it should be possible to develop other formulae that are better suited for ancient buildings. Our analyse is using a new leading-edge technology, the scratching test, developed at Polytechnic Faculty of Mons (Faculté Polytechnique de Mons). At the same time, mortar samples from buildings and vestiges of all periods from all over the Walloon Region are being collecte...
The petrography of lime inclusions in historic lime based mortars
Lime inclusions are fine to coarse grained lumps of unmixed binder material commonly found in old mortars in historic buildings. Interpretations for their origin have been advanced including the practice of "hot mixing" or "dry-slaking" of quicklime direct with sand and water and poor mechanical combination of the material prior to application. Their composition and microstructure may provide clues as to their origin and to their preservation. Several historic mortars from Scotland and Belgium have been investigated. This paper presents details of the inclusions found in these mortars. A number of different textures are evident from clotted, peliodal to psuedomorphs of precursor limestones. The presence of cores of unburnt limestone with coronas of hydrated lime texture suggest a possible reason for the integrity of lime inclusions throughout the mixing and application procedures. Lime inclusions also provide material for the assessment of the composition and provenance of the raw materials, and the freshly burnt lime, without the influence of mortar additives such as pozzolans. The presence of lime lumps are useful in suggesting the nature of historic mortar production and application practices.
2016
The topic of this study is the mineralogical and petrographic characterization of lime-based mortars of Hellenistic-Roman age (3rd century BCE), collected from a residential area located in the present historical centre of Palermo, near the remains of the Punic-Roman walls. The collected mortars have been analyzed by optical microscopy, X-ray powder diffraction analysis and scanning electron microscopy, coupled with energy-dispersive spectrometry. The aim of the study was the characterization of the mortars as pertaining to their aggregate and binder composition, aggregate size distribution and aggregate/binder ratio, so as to establish the provenance of raw materials and acquire information useful in terms of formulating suitable restoration mortars. The mineralogical and petrographic investigations allowed to recognize four different recipes used for the formulation of the studied mortars. The aggregate is made up of different proportions of alluvial calcareous and siliceous sands...
Chemical Analysis of Historic Lime Mortars: Role of Sample Preparation
Advanced Materials Research, 2015
The characterization of historic lime mortars is crucial for many cultural heritage conservation issues. In this work, the characterization of a historical lime mortar is described. Samples for chemical analysis were obtained after different milling times and using the RILEM acid digestion method on several replicates. Qualitative and quantitative determination of phases in the mortar and in the residues after acid attack and the potential presence of CaCO3 polymorphs, were accomplished with X-ray powder diffraction. Results suggest that representativeness of the sample and the homogenisation, although not always achievable in conservation practice, are strongly affecting results.
Radiocarbon dating of mortar based on hydraulic lime. Advantages, disadvantages, limitations
Hydraulic lime mortars have been an important segment of human society for thousands of years. Recipes of production, construction behavior over time and physico-chemical investigations for material characterization and reconstitution of recipe for buildings restoration are continuing challenges. Neither radiocarbon method is an exception; the dating of mortars remains one of the most difficult problems to solve, and therefore collective experience at international level can led to outlining advantages, disadvantages and limitations of its use. This experience, taken over and developed in the RoAMS laboratory of IFIN-HH, can be highlighted by a comparative short presentation of three different case studies, namely Porolissum / Moigrad ancient Roman city and military camp in Dacia, Marienburg / Feldioara Medieval Fortress near Braşov, and chapel church and Chindia Tower areas belonging to Princely Medieval Court at Târgovişte. All three cases are located in Romania and represent important objectives of the national cultural heritage.
Engineering Geology, 2014
This research has focused predominantly on assessing the most important physical and mechanical properties of Leitha Limestone rock samples and of a separate oolitic limestone sample, in conjunction with sedimentological and microfacies analyses. The microfacies characteristics of these samples, together with their other technical properties, help to explain why the Leitha Limestone is an important material for monuments and for restoration work. Rock samples for laboratory tests were collected from 12 sites located within alpine Neogene basins. Samples for the assessment of rock properties were taken from abandoned quarries in the Kaisersteinbruch-Bruckneudorf military area, from abandoned and active quarries at St. Margarethen, and from the Aflenz underground quarry. To broaden the scope of the investigations previous research results from quarries at St. Margarethen, Mannersdorf, Wolfsthal, and Hundsheim were also included. Thin sections were made from one of the drill cores from each quarry. The microfacies analysis of the Leitha Limestone samples indicated a spectrum from encrusting coralline algae boundstones to coralline algae grainstones and rudstones, and also included variable quantities of other bioclasts and siliciclasts. The detailed results revealed considerable differences between the various samples, which are considered to be from a shallow marine, intertidal to subtidal paleoenvironment with variable hydrodynamic conditions. The rock quality and durability were assessed through laboratory testing of physical and mechanical properties, including measurements of real and apparent density, porosity, water absorption capacity, uniaxial compressive strength (UCS) for both dry and water-saturated rock samples and for samples following repeated freeze-thaw cycles, the coefficient of softening and the coefficient of freezing. All investigated rock samples had different porosities and absorption capacities. They also differed in their UCS values, which were very variable but mostly belonged to the weak rock category (UCS below 50 MPa). Five of the tested rock samples had higher UCS values and were consequently ranked in the firm rock category. The microfacies investigation proved to be a valuable tool for interpreting the measured engineering geological properties, in particular the porosity and rock strength.
Analysis and recognition of dolomitic lime mortars
Mortar analysis usually is performed by microscopy and wet chemical methods, at times completed by X-ray diffraction, infrared spectroscopy or other more complicated methods. For pure lime mortars with a river sand filler, mainly consisting of quartz and feldspar, the analysing methods and the interpretation of the results are straightforward, however analysis and interpretation become more complicated if there are other binders and/or aggregate types present. Our paper focuses on dolomitic lime mortars. We lie out, that depending on the kind of raw material that was burned, on the burning temperature, on the way of slaking, on the manner of the actual mortar preparation and finally on the further history of the mortar, different mineral phases will actually grow in dolomitic lime mortars. The possible magnesium phases are listed and discussed in regard to their likelihood of being present, Further it is shown, what information is necessary to be able to interpret the analytical results and to distinguish dolomitic lime mortars from other mortar types. It is also shown, that a very useful analytical method for mortars, is thin section microscopy. It allows to recognise the mineral phases and also to observe, whether these minerals are present as a part of the aggregate or of the binding media, a differentiation which is crucial for the interpretation. Other analytical methods like XRD or IR are shown to be very helpful to give additional information on constituents that are too small in grain size to be analysed by polarising microscopy, however some products of the setting reaction of dolomitic lime mortars cannot be detected by these methods. Further we give some examples of dolomitic lime mortars and discuss the analytical limitations.