Historic Lime Research Articles

Chemical Weathering of Lime Mortars from the Jahangir Tomb, Lahore-Pakistan

The effects of environmental pollution on cultural heritage have been widely studied in different parts of the world over the last few decades but not with the reference to Pakistan, although cultural heritage in this part of the world is deteriorating at an alarming rate. Determination of the deterioration processes and causes are the fundamental parameters for the preservation on scientific grounds of these cultural assets. This study investigates the effect of environmental pollution on the facades of the 17th century historic monuments of Jahangir Tomb in Lahore (Pakistan). For this purpose, samples were collected from weathered as well as from sound interior surfaces. The samples were characterized by XRF, XRD, SEM-EDS and stereomicroscopy/wet chemistry to understand the weathering mechanisms and products. Those are mainly comprised of sulphates, chlorides and nitrates along with high contents of soil particulates and biological colonization. Results show that chemical weathering is occurring at the mortar-atmosphere interface of the historic fabric, conjoining the petrographic characteristics of the mortars and enveloping atmospheric composition. This interaction is responsible for the current deterioration of the historic lime mortars.

Simple Analysis of Historical Lime Mortars

A laboratory experiment is described in which a simple characterization of a historical lime mortar is made by the determination of its approximate composition by a gravimetric method. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) are also used for the qualitative characterization of the lime mortar components. These types of experiments are particularly suitable to teach aspects of general chemistry and to present techniques such as FTIR or XRD at an introductory laboratory level to students who have their major in courses that are related to cultural heritage but also have science disciplines, such as chemistry.

Medium-term soil pH and exchangeable aluminium response to liming at three high country locations

Acid soil conditions and associated aluminium (Al) toxicity pose a serious impediment to legume establishment, persistence and productivity in high country. However, data that report soil exchangeable Al concentrations in response to lime applications are scarce. Three historical (3-8-year-old) lime trial soils were sampled for soil pH and exchangeable aluminium (Al). Soil pH ranged from 4.8 to 7.5, with exchangeable Al concentrations (CaCl2 extraction) of 0.2 to 24 mg Al/ kg. Soil pH and exchangeable Al changed significantly when lime was applied, but the shape of the response differed between the three site locations. The soil pH changes (0-7.5 cm horizon) were 0.16, 0.10 and 0.20 pH units/t lime applied. Critical research needs to be conducted to investigate the key soil factors and mechanisms that result in Al toxicity in high country soils to enable development of mitigation strategies. On-farm decisions on lime rates and legume species suitability need to be based on soil pH and Al testing from individual farm blocks rather than using "rule of thumb" approaches. Keywords: soil pH, soil exchangeable aluminium, lime, pasture legumes

Assessment of historic Tilia codrata wood by solid-state 13C CPMAS NMR spectroscopy

Abstract Historic lime ( Tilia cordata Mill.) wood samples, differing by their provenance, conservation status and period have been investigated by solid-state carbon-13 cross polarization magic angle sample spinning nuclear magnetic resonance ( 13 C CPMAS NMR) spectroscopy. Structural and chemical modifications were assessed by comparing the historic samples with a reference wood sample. The conventional NMR measurements followed by the 13 C resonance integral intensities of the wood samples have been carried out in order to acquire information of the chemical changes due to the natural ageing process taking place over the years. The main results concern the decrease of the carbohydrates moiety, especially the decrease of the hemicelluloses and amorphous cellulose signals, while the signals for aliphatic and methoxyl carbons from lignin present and increase of the intensity up to 120 years then start to decrease. At the same time a slight widening of the amorphous carbohydrate signals was observed, which may evidence the occurring of some chemical rearrangements, with the formation of new chemical species. These lead in the 13 C NMR spectra to the line broadening of the signals induced by their chemical shifts dispersion.

Characterization of historical lime plasters by combined non-destructive and destructive tests: The case of the sgraffito in Bożnów (SW Poland)

Mortars used in the two-color sgraffito, dated back to 17th century, have been investigated in order to fully characterize the material and to evaluate the state of its preservation. The non-destructive tests carried out “in situ”, comprising thermal imaging and ground penetrating radar, revealed the inner structure of the decoration, which was exfoliated from the wall in ca. 90%. The obtained thermograms and the GPR scans allowed to choose sampling areas for subsequent destructive-tests, performed by means of optical microscopy, chemical analysis, granulometric analysis, X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and differential thermal/thermogravimetric analysis. The results reveal the decoration is composed of two separate coats of lime plasters: (1) the primer plaster and (2) the sgraffito plaster. Both the coats appeared to be a mixture of lime binder (aerial lime) and fine- to medium-grained sand, with addition of small amounts of brick chunks and charcoal. The latter is abundant in the sgraffito plaster, serving as a coloring agent. For elimination of plasters exfoliation, a calcareous PLM-A product of C.T.S. Italy was applied by injection. The non-destructive studies performed after this conservation demonstrates that the rehabilitation work has reestablished homogeneous structure of the sgraffito decoration.Our study indicates that full characterization and proper reconstruction of ancient mortars could be attained by complementary employment of destructive and non-destructive test methods. Moreover, repetition of the non-destructive tests after the rehabilitation works provide valuable insights into their effectiveness.

Identification, Extraction, and Preparation of Reliable Lime Samples for 14C Dating of Plasters and Mortars with the “Pure Lime Lumps” Technique

Radiocarbon dating was first applied to historic lime mortars during the 1960s. However, despite the relative simplicity of the technique in principle, a number of subsequent studies have highlighted important aspects that should be considered. One of the most significant of these challenges arises from sample contamination by carbonaceous substances such as incompletely burnt limestone and aggregates of fossil origin containing “dead” 14C. More recent studies have shown that in the majority of old lime-based mixtures the contamination problem can be avoided through selection of pure lime lumps. These particular types of lumps are believed to originate from areas where the lime is incompletely mixed with the aggregate. It has been demonstrated that even a single lime lump can provide sufficient material for a 14C date of the mortar from which the lump was taken (Pesce et al. 2009). This paper describes the practical challenges associated with location, extraction, and preparation of 4 lime lumps extracted from 2 new sites for 14C dating. These include distinguishing the lime lumps from other lumps present in the matrix and the removal of material surrounding the lime lump. The coherence of 14C dating with other archaeological information on the chronology of historic sites is highlighted through case studies.

Determination of CaCO3 and SiO2 content in the binders of historic lime mortars

The binders of historic mortars composed of small grain sized silica (SiO2) and carbonated lime (CaCO3) are considered as the main part that give hydraulic character and high strength to the mortar. In this study, FTIR, SEM–EDS, LIBS and XRD spectroscopy were used to find out the weight ratios of CaCO3 to SiO2 in the binders of historic lime mortars. For this purpose, a series of pure calcium carbonate and silica mixture were prepared in ten combinations in varying ratios from 0.5 to 5. Calibration curve was prepared for each analysis by plotting the peak area or intensity ratios of CaCO3 to SiO2 versus the weight ratios of CaCO3 to SiO2. A good linear correlation coefficient was obtained for each analysis respectively. The analyses were then tested on the binder of the Roman mortar samples. The results indicated that FTIR, SEM–EDS and LIBS spectroscopy are convenient tools to determine the weight ratios of CaCO3 to SiO2 in the binders of mortars. But XRD spectroscopy is not convenient for quantitative analysis of binders due to the presence of varied amounts of amorphous or poor crystalline silica in their compositions.

The Influence of Particle Size and Structure in Hydrated Lime on the Properties of the Lime Putty and Lime Mortar

In this work, scanning electron microscopy (SEM) analysis of lime slaked in different ways and analysis of thin section of lime putty and mortar specimens by light microscopy was combined with practical tests and field studies to evaluate the impact of the slaking technique on the properties of the lime putty as well as the structure of the fresh and carbonated mortar. The lime slaking methods studied were wet slaking and earth slaking, giving lime putties with very different consistency and workability. The aim of this work was to use microscopy techniques to explain these differences in properties and to investigate if it is possible to use these analytical methods to recognize the lime-slaking technique used in a historical lime mortar. The results obtained by SEM show significant differences in structure between the lime putties. The earth-slaked lime consists of relatively large particles that are packed in a porous system compared with the wet-slaked lime with very small particles closely packed in a dense structure. After storing, the wet-slaked lime gives a putty that has a dense and clearly defined stratified structure, whereas the earth-slaked lime is porous and has no stratification.

Historic lime mortars: potential effects of local climate on the evolution of binder morphology and composition

Abstract This research explores preliminary observations regarding the potential effects of local climate conditions on the evolution of binder morphology and the composition or mineralogy of historic lime mortars. Samples were collected from historic buildings, one group dating to c . late nineteenth century and an older group from c . Sixteenth–Seventeenth century, with both groups representing distinct climates. The samples were then prepared and subjected to polarized light microscopy (PLM), point count, scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) and backscatter election imaging (BSE) analysis to investigate differences in porosity, environmental contaminants and morphological characteristics of the lime binder. By examining the effects of climate on lime mortars, conservators can improve identification and condition assessment of historic lime mortars, better understand causes of damage and decay attributed to previous mortar repairs, and formulate more appropriate conservation mortars to improve protection and conservation of our architectural heritage.

Α Nano Approach to Consolidation of Degraded Historic Lime Mortars

This paper presents a comparative study of the effects of calcium hydroxide based agents on consolidating a lean lime mortar. In the first part, it describes the properties and characteristics of CaLoSiL® – a new stone strengthener based on colloidal suspensions of lime nanoparticles in various solvents. It further summarizes the results of recent tests on the influence of applying nano-agents based on colloidal calcium hydroxide dispersed in ethanol or isopropyl alcohol (CaLoSiL®), and compares them with the effects of lime water and with a traditional barium hydroxide treatment. The tests were carried out on non-standard test specimens fabricated from a lean mortar (1:9) and developed specially for the purpose of testing the relatively low strengthening effects that are typical for lime water consolidation. The comparison presented in this paper is based on the mechanical characteristics of consolidated lime mortar.

Stable carbon and oxygen isotope investigation in historical lime mortar and plaster – Results from field and experimental study

Abstract Lime mortar and plaster were sampled from Roman, medieval and early modern buildings in Styria. The historical lime mortar and plaster consist of calcite formed in the matrix during setting and various aggregates. The stable C and O isotopic composition of the calcite matrix was analyzed to get knowledge about the environmental conditions during calcite formation. The δ 13 C matrix and δ 18 O matrix values range from −31 to 0‰ and −26 to −3‰(VPDB), respectively. Obviously, such a range of isotope values does not represent the local natural limestone assumed to be used for producing the mortar and plaster. In an ideal case, the calcite matrix in lime mortar and plaster is isotopically lighter in the exterior vs. the interior mortar layer according to the relationship δ 18 O matrix = 0.61 · δ 13 C matrix − 3.3 (VPDB). Calcite precipitation by uptake of gaseous CO 2 into alkaline Ca(OH) 2 solutions shows a similar relationship, δ 18 O calcite = 0.67 · δ 13 C calcite − 6.4 (VPDB). Both relationships indicate that the 13 C/ 12 C and 18 O/ 16 O values of the calcite reflect the setting behaviour of the lime mortar and plaster. Initially, CO 2 from the atmosphere is fixed as calcite, which is accompanied by kinetic isotope fractionation mostly due to the hydroxylation of CO 2 ( δ 13 C matrix ≈ −25‰ and δ 18 O matrix ≈ −20‰). As calcite formation continued the remaining gaseous CO 2 is subsequently enriched in 13 C and 18 O causing later formed calcite to be isotopically heavier along the setting path in the matrix. Deviations from such an ideal isotopic behaviour may be due to the evolution of H 2 O, e.g. evaporation, the source of CO 2 , e.g. from biogenic origin, relicts of the natural limestone, and secondary effects, such as recrystallization of calcite. The results of the field and experimental study suggest that isotope values can be used as overall proxies to decipher the origin of carbonate and the formation conditions of calcite in the matrix of ancient and recent lime mortar and plaster. Moreover, these proxies can be used to select calcite matrix from historical lime mortar and plaster for 14 C dating.

GEOCHEMICAL CHARACTERIZATION OF ARCHAEOLOGICAL LIME MORTARS: PROVENANCE INPUTS*

Chemical and mineralogical analyses were carried out on historical lime mortars from the parish church of Santa María La Real (Guipúzcoa). The study included various periods ranging from Roman to modern times and allowed the identification of various types of raw materials. In order to obtain pure binder, free of carbonate aggregates and charcoal particles, an innovative binder separation method was implemented. The chemical composition of the binder allows discrimination of different provenance areas for the raw materials, although those areas do not correlate with specific historical periods. In addition, the influence of burial processes on the primeval chemical features has been assessed and reveals that modern mortars display greater chemical modification than the Roman mortars.

HISTORICAL LIME PRODUCTION IN SOUTHEASTERN ARIZONA

The production of lime by burning limestone has been practiced in the Americas for at least 6,000 years and beginning in Spanish Colonial times was an important cottage industry in southern Arizona. Lime kilns, however, have largely been overlooked, ignored, or avoided by archaeologists and historians alike. Their excavation is uncomfortable and often relatively fruitless, yielding architectural data but little to suggest when a kiln was operated, or by whom. Archival data are also often lacking because kilns were constructed in areas of optimum resources, with little effort to secure ownership of the land. This article reviews historical lime production in southern Arizona with a focus on the Tucson Basin.

Evaluation Of Properties OfMagnesian Lime Mortar

Due to their nature and function, historic lime mortars weather and often need to be replaced. Petrographic analysis of original mortars from Ardamullivan Castle evidenced that they were fabricated with a dolomitic limestone. Within, Ardamullivan Castle’s conservation programme it was considered to replicate the original mortars to undertake conservation works to the Castle. However, documentary research revealed that there is a lack of agreement on the properties of magnesian lime as well as a lack of experimental work in the subject. Therefore, it was deemed necessary to evaluate the properties of magnesian lime prior to its use. To this aim, dolomite was calcinated in a limekiln and the lime obtained slaked for a year. Magnesian lime mortars were then fabricated and tested in the laboratory. Porosity, densities, compressive strength, capillary suction and absorption were evaluated. The lower values of capillary raise, porosity and absorption obtained for the magnesian lime mortars when compared to those of feebly hydraulic limes suggest that magnesian lime binders would perform superiorly in areas subject to the presence of moisture. In compression, the feebly-hydraulic mix is four times stronger than the mg-lime mortar. The mg-lime mortar outperforms the feebly-hydraulic lime mix in all tests except for compressive strength. However, the compressive strength of the mg-lime mix is enough to withstand the stresses and strains typically induced when confined within conventional masonry. The results of this investigation suggest that, provided the lime has been adequately calcinated and slaked, mg-lime mortar can perform well as a building material.

Analysis of Historic Lime and Gypsum Plaster Floors—Part One

The survival and continued use of historic lime and gypsum plaster flooring is commonplace in certain parts of the United Kingdom, and yet it remains almost unknown in other parts of the country. The potential for loss and damage to such floors, whether through ignorance or indifference, is great; and this has prompted a study of this traditional form of construction in order to engender greater interest and promote more appropriate forms of repair or reinstatement. The first part of this paper describes the history and use of lime and gypsum plaster flooring, comments briefly on the related use of earth and modified earth floors, and describes the composition of traditional plaster flooring through documentary sources.

Analysis of Historic Lime and Gypsum Plaster Floors—Part Two

The survival and continued use of historic lime and gypsum plaster flooring is commonplace in certain parts of the United Kingdom, and yet it remains almost unknown elsewhere in the country. The potential for loss and damage to such floors, whether through ignorance or indifference, is great and has prompted a study of this traditional form of construction in order to engender a greater interest and promote more appropriate forms of repair or reinstatement. The second part of this paper considers the sampling and analysis of historic plaster floors, presents the results of simple and sophisticated forms of analysis, together with the results of compressive strength testing of new plaster floor mixes, and considers aspects of repair and maintenance.

The petrography and microstructure of medieval lime mortars from the west of Scotland: Implications for the formulation of repair and replacement mortars

Twelfth and thirteenth Century lime mortars from the west of Scotland were examined using optical polarising microscopy and SEM on impregnated, polished thin sections, and of fracture surfaces by secondary electron SEM. The non-hydraulic calcite binder in these mortars is loclly inhomogenouse, exhibiting variations in texture and density. Spongiform binder with porosity of size 10–20μm has sharp transitions with neighbouring zones of dense binder. Sub-isopachus concentrically accreted calcite pore linings delineate extensive areas of secondary porosity created by dissolution of binder. Common lime inclusions (lime lumps) suggest that hot mixing processes were used. Textural characteristics of lime lumps are similar to reaction rims on partially burnt primary source limestone suggesting that provenance for the lime can be deduced from the petrographic features of incompletely burnt relics. The evidence for the dissolution and reprecipitation of carbonate binder materials suggests the need for a careful reconsideration of practical historic mortar analysis. These historic mortars are texturally and compositionally more complex than their modern equivalents. These textures provide evidence for historic lime burning and mortar mixing practices in Scotland during the middle ages, as well as ageing processes, and allows the possibility of a more sophisticated approach to formulating compatible replacement mortars.

Petrographical, mineralogical and chemical investigation of 17th and 19th century lime mortars in the St.-Michael's church (Leuven, Belgium)

Petrographical, mineralogical and chemical analyses have been used to characterize historical lime mortars in the Saint-Michael's church (Leuven, Belgium). An analysis method is proposed for a mineralogical (petrography, XRD-analysis and SEM-EDX-analysis) and chemical characterization of historical mortars. Four groups of mortars have been distinguished and indications for the processes of mortar production and for the provenance of the raw materials used for these mortars have been found. Lime was burnt in vertical lime kilns and dry slaked. The provenance of the aggregate was local and the lime was imported from Namur (SW of Belgium) and Tournai (SW of Belgium). A change in binder type and properties of the lime mortars from the 17th century original mortars (air-hardening) to the 19th century restoration mortars (hydraulic) has been observed.

Lime Mortars for Brickwork: Traditional Practice and Modern Misconceptions—Part Two

The revival in the use of traditional lime mortars for the repair, restoration and conservation of historic buildings in the United Kingdom over the past 25 years continues to gain momentum as designers and builders alike recognize the importance of using materials that are sympathetic to those originally used for the construction of such buildings. This work has tended to focus on the use of pure non-hydraulic slaked lime putties as the principal binder for all mortars, which has led both to the widely held belief that all historic lime mortars were prepared in this manner, and to a general perception that hydraulic limes are similar in behaviour to modem cements.These views are essentially inaccurate and contradict much of the written works on bricklaying mortars that reflect the thinking and practices of architects and knowledgeable master craftsmen from the seventeenth century onwards. This is especially so in relation to the city of London, from where such influence was to spread rapidly throughout the country and to the British colonies. The vast majority of brick buildings that are now in need of care and attention date from after this period, and it is therefore timely to reappraise traditional practice and modem misconceptions.

Lime Mortars for Brickwork: Traditional Practice and Modern Misconceptions—Part One

The revival in the use of traditional lime mortars for the repair, restoration and conservation of historic buildings in the United Kingdom over the past 25 years continues to gain momentum as designers and builders alike recognize the importance of using materials that are sympathetic to those originally used for the construction of such buildings. This work has tended to focus on the use of pure non-hydraulic slaked lime putties as the principal binder for all mortars, which has led both to the widely-held belief that all historic lime mortars were prepared in this manner, and to a general perception that hydraulic limes are similar in behaviour to modem cements.These views are essentially inaccurate and contradict much of the written works on bricklaying mortars that reflect the thinking and practices of architects and knowledgeable master craftsmen from the seventeenth century onwards. This is especially so in relation to the city of London, from where such influence was to spread rapidly throughout the country and to the British colonies. The vast majority of brick buildings that are now in need of care and attention date from after this period, and it is therefore timely to reappraise traditional practice and modem misconceptions.