THE MANUFACTURE of LIME and ITS USES IN the WESTERN ROMAN PROVINCES

Summary: The widespread use of hydraulic lime mortars and concretes was chiefly a Roman development, but, in addition, lime produced by burning calcium carbonate at temperatures between 900°-1100° C was used in agriculture, tanning and medicine. Cato has described the construction and operation of a periodic lime-kiln and with the evidence from excavated sites the original process can be reconstructed. For most farming purposes, however, lime was produced in less substantial pits and in above-ground stacks or clamps.     

Characterization of archaeological lime mortars in a Ming dynasty tomb: A multi-analytical approach

Lime mortars have played an important role in constructing ancient Chinese masonry structures, including city walls, buildings, and tombs. A tomb built with lime mortars and stones belonging a Ming high-ranking official, Xu Jie, was discovered in Huzhou City of China. Eight different samples from Xu Jie’s tomb, representing four types of lime-mortar-based materials: joint mortar between stone bricks, bedding mortar, grouting mortar, and plaster mortars were collected for analysis and comparison. The characterization of the construction materials has therefore become of primary importance. The function of each mortar was reported and studies into the micro-textural features and mineralogical compositions of those mortars were performed via a multi-analytical approach. The joint mortars were all found to be aerial lime mortars with predominately lime. The bedding mortar was found to consist of lime, soil and sand, typical of a tabia mortar. The grouting mortar was found to consist of lime and ground contact metamorphosed limestone. Analysis of plaster sample taken from the roof of the main tomb identified the presence of calcium stearate/palmitate, indicating the usage of plant-based tung oil as an additive. The analytical results will promote our understanding of Ming architectural technology and craftsmanship, and provide critical information for the conservation of Xu Jie’s tomb.     

Characterization of ancient building lime mortars of Anhui province,China: A multi-analytical approach

The characterization of lime mortars has become of primary importance in order to obtain information about the raw ingredients and building technology of ancient masonry structures. Five different samples from Anhui province, China, representing two types of lime mortar-based materials: joint mortars between the bricks of the city wall and lime mortar sealing a tomb coffin, were collected for analysis. Archaeological information about the samples was reported and studies into the microtextural features and mineralogical compositions of those mortars were performed via a multi-analytical approach. The joint lime mortars between the bricks of city walls, including Mingzhongdu city wall, Mingzhongdu Xihua gate foundation, Zhengyangguan city wall and She county city wall, were found to be aerial lime mortars. The lime mortar from Nanling Tieguai Song dynasty tomb was analysed and found to be a pozzolanic mortar consisting of lime, clay, sand and cocciopesto-like materials. The analytical results serve as a critical reference for the maintenance and restoration of ancient city walls in Anhui province, and as a starting point for searching for ancient Chinese pozzolanic mortars and technology for making those mortars.     

RADIOCARBON DATING OF MORTARS FROM ANCIENT GREEK PALACES

This study deals with radiocarbon dating of lime mortars which were used as supports for Mycenaean and Minoan paintings. The ¹⁴C dates are. on the whole, compatible with the historical data. and thus show that a large proportion of the Mycenaean surficial coatings can be dated by the radiocarbon method. However. in order to determine the age of the mortars accurately. it is necessary to evaluate the amount of sedimentary carbonate which may have been added to them. It is shown here that the oxygen and carbon isotope compositions of lime mortars are significant indicators that such a mixing actually took place.     

天然水硬性石灰在不同碳化条件下的水化反应

为了探究不同碳化条件对天然水硬性石灰水化过程的影响,继而认识到养护条件中的碳化作用对天然水硬性石灰早期强度和养护时间的影响,模拟制备了不同碳化条件下的样品,用X射线衍射(XRD)、热重分析(TG)、红外光谱(IR)、扫描电子显微镜和X-射线能谱分析(SEM-EDX)测试和比较养护前后天然水硬性石灰成分、结构、形貌的变化。研究表明,天然水硬性石灰水化生成水化硅酸钙(CSH)、氢氧化钙(Ca(OH)_2)的反应与CSH、Ca(OH)_2的碳化反应同时进行,并且Ca(OH)_2的碳化速率大于水化反应生成Ca(OH)_2的速率。随着养护龄期增加CSH逐渐由细小的针棒状结构生长为粗大的棒状结构,随后又逐渐变短并最终完全碳化为方解石晶型的碳酸钙(CaCO_3)形貌。天然水硬性石灰水化产物的碳化作用能促进其水化反应进程。     

EVALUATION OF BINDER/AGGREGATE RATIOS IN ARCHAEOLOGICAL LIME MORTARS WITH CARBONATE AGGREGATE: A COMPARATIVE ASSESSMENT OF CHEMICAL,MECHANICAL AND MICROSCOPIC APPROACHES*

This paper reports on the comparative evaluation of traditional and innovative methods for the investigation of mortar technology. Preliminary results of various approaches to determining the mix proportions in lime mortars with carbonate aggregate are presented. Quantitative analysis was tested on ad hoc prepared mortars of known composition containing carbonate aggregates of different origin (travertine and Bath limestone). Wet chemical methods, manual disaggregation and Digital Image Analysis of thin sections and cross‐sections stained with Alizarin Red S were tested. The advantages and drawbacks of the different approaches are discussed, and applications to the analysis of archaeological mortars and plasters are highlighted.     

我国传统镁质石灰初步研究

对我国从明代到民国的建筑灰浆的化学成分、矿物成分等分析发现,部分砌筑及抹灰灰浆为镁质石灰,MgO含量达到5%~26%。特别是取自河北、北京等地长城的传统石灰样品全部为镁质石灰。镁质石灰与钙质石灰比较,具有强度高、吸水率低的特点,从而具有更佳的抗冻融性能。此外,镁质石灰收缩低、易于施工。镁质石灰煅烧需要的温度低于钙质石灰,能耗低。鉴于传统镁质石灰在中国的研究尚为空白,建议系统地开展镁质石灰研究,研究内容包括原材料类型及分布、煅烧温度、消解方式、配比优化等。同时宜研究镁质石灰在严重大气污染下的耐久性及镁质石灰相关建筑遗产的保护修复技术等。     

Characterization of Hydraulic Lime Mortar Containing Opuntia ficus-indica as a Bio-Admixture for Restoration Applications

Many successful and long lasting structures that contain lime mortars are hydraulic in nature. Organic admixtures are added to lime mortar mix to modify their fresh and hardened state properties. The present work proposes plant extract as bio-admixture for repair mortar towards the protection of heritage structures. The effect of cactus extract on the properties of hydraulic lime mortar is studied. Mortar´s composition is selected with respect to the composition of historic mortars and modern restoration practice. Cactus extract was added to the lime sand mixture with varying concentrations (25%, 50%, 75%, and 100%) and with different fermentation periods of 0, 1, and 2 days The consistency and workability of modified mortar, mechanical behavior, water absorption, porosity, and water/salt absorption through capillary rise, salt crystallization have been studied. Micro structural properties of the resulting mortar have been evaluated by XRD and FT-IR to identify their mineralogical composition and morphology by SEM-EDX. It is observed that addition of 75% cactus extract with 1-day fermentation produces maximum positive effect on the strength and durability properties of lime mortar. It improves the mechanical characteristics, limits water and salt absorption by capillarity into mortar and also show resistance to salt crystallization cycles.     

Investigation of lime mortars and plasters from archaeological excavations in Hippos (Israel) using Electron Paramagnetic Resonance

This study presents the preliminary results of investigation of the lime mortars and plasters from archaeological excavations in Hippos (Israel), using Electron Paramagnetic Resonance (EPR) spectroscopy. The research was conducted in order to characterize the building material and its reaction to ionizing radiation. The ancient settlement Hippos, situated on the east shore of the Sea of Galilee, functioned from the 3^rd cent. BC until it was destroyed by the earthquake in 749 AD. Lime mortars and plasters show carbonate and locally gypsum character of binder and different kind of aggregate. Samples were γ-irradiated and measured using X-band EPR spectrometer. Computer Resolution Enhancement Method was applied to the complex spectra. Some of the γ-induced EPR signals were attributed to CO₂ ^? and CO₃ ^3? paramagnetic centres. Exponential growth of the dose response curve above 1 kGy and saturation for doses above 20 kGy was observed. For doses lower than 1 kGy the dose response curve has a linear character. The presence of γ-sensitive carbonate paramagnetic centres could indicate that, after further studies, well-chosen samples of mortars and plasters might be suitable for EPR dating, assuming the centres have been sufficiently bleached during the manufacturing process.     

EFFECTS OF MILLING: A POSSIBLE FACTOR INFLUENCING THE DURABILITY OF HISTORICAL MORTARS

In their literary texts, some classical Roman authors such as Gaius Plinius Secundus and Marcus Vitruvius Pollio stress the importance of milling when preparing mortars. Following these indications, this work describes the effects of milling between lime (calcium hydroxide) and clay brick powder before and after the addition of water. Starting and resulting materials were investigated by XRPD, SEM/EDS, differential scanning calorimetry and thermogravimetry (DSC/TC), colorimetry, densimetry and porosimetry. Prolonged milling changes the mineralogy of the starting materials and increases their reactivity. The final lime pastes, starting from materials milled for varying periods of time, had different mineralogical and physical characteristics. These results may help to clarify the reasons for the marked differences in durability of some historical mortars.     

Effect of natural polymers from cissus glauca roxb on the mechanical and durability properties of hydraulic lime mortar

The tradition of using lime as a binder has been in practice over the centuries and is cited in the architectural feats of all kinds of civilizations. Besides the basic ingredients of lime, sand and water, organic admixtures were also mixed into the mortars to modify fresh and hardened state properties as well as to enhance its durability. The motivation of the present study was to develop a replacement of synthetic admixtures by the bio-admixtures. The plant extract of Cissus glauca Roxb (CGR) which is being used in ancient temples and monuments in Kerala has been tested as admixture in varying concentrations and fermentation periods in lime mortar mix. The admixture is polysaccharide rich and a moisturizing agent.

Tests were conducted to measure changes in microstructure of the mortar; fresh state properties such as setting time and workability, mechanical properties such as compressive strength and flexural strength. Also, physical characteristics of admixture modified mortars such as bulk density, porosity and water absorption were also determined. Morphological analysis using SEM with EDX, mineralogical analysis using XRD and organic analysis adopting FT- IR have been done to validate the results of mechanical and physical tests. Capillary water and salt absorption by suction and resistance to salt crystallization cycles were measured as an indicator of durability properties.

The admixture modified mortar resulted in increased mechanical properties and reduced water absorption. It also limits the capillary rise of water and salt intrusion through the hydrophobic nature. The admixture modified mortar have also offered better resistance against the damaging action of deteriorating salts such as sodium chloride and sodium sulphate crystallization cycles. Polysaccharides and proteins in the plant extract interact with the calcium hydroxide of slaked lime and forms complexes. Hence the, natural polymer has increased the durability of hydraulic lime mortars used for repair and it could be a natural alternative to synthetic admixture.     

Analytical Investigations of Traditional Masonry Mortars from Ancient City Walls Built during Ming and Qing Dynasties in China

With the development of China’s economy, the protection and conservation of ancient buildings were put on the agenda. However, the current understandings on Chinese traditional mortars are limited and rarely reported in the literature. In this article, the authors investigate seven ancient city wall sites built during the Ming and Qing dynasties (1368–1841 AD) in situ, and subsequently the laboratory analysis were carried out on the collected mortar samples. The characterizations of mortar samples were performed using digital microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), simultaneous thermal analysis (TG-DSC), as well as wet chemical analysis. The analytical results show that pure lime mortar was widely used in construction during the Ming and Qing dynasties, and it was also a common practice adding sticky rice soup into slaked lime to form sticky-rice lime mortar during preparations. This organic-inorganic composite material could effectively improve mechanical strength of the lime mortar. Moreover, it was first found that the sticky-rice lime mortar sample from Kaifeng ancient city wall contained very fine quartz aggregates, with an approximate binder/aggregate ratio of 1:1. The appearance of this type of mortar probably indicates a great development of Chinese traditional mortars during the mid-19th century.     

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.     

MORTAR STUDIES TOWARDS THE REPLICATION OF ROMAN CONCRETE

The use of strong and durable materials is one essential ingredient leading to the survival of many monumental Roman concrete structures. Replicated concrete mortars with different lime to pozzolan ratios, encompassing the range likely to have been used by the Romans, have been studied here to determine their relative compressive strengths as a function of time. This has been supplemented by the use of the scanning electron microscope to delve into the structure and composition of the binders formed within the strongest and weakest mortars, leading to a deeper understanding of the reasons for the differences in compressive strength.     

水硬石灰在花山岩画加固保护中的应用研究

水硬石灰兼具石灰和水泥的优点,低收缩、耐盐、适中的抗压和抗折强度、水溶盐含量低,同时与传统的砖石建筑兼容性好,是一种天然、无污染、耐老化的无机材料。本工作针对花山岩画的开裂特点制订出相应的力学参数要求,配制出两种不同的水硬石灰砂浆,并对这两种砂浆的力学性能进行了分析。同时探讨了不同养护条件对水硬石灰砂浆拉拔强度的影响。现场试验结果说明,填补粘结材料可以提供一定的粘结强度,并且具有使用方便,污染小的特点,可用于花山岩画开裂岩体应急保护加固处理。     

New evidence of early use of artificial pozzolanic material in mortars

Hydraulic building composites, such as mortars and plasters, produced with artificial pozzolanic materials, became widely popular thanks to the Romans. Reports on earlier uses of such composites can also be found, mainly in archaeological and historic documents. These date back as far as the time of Minoan and Mycenaean civilizations. Here, we present a holistic analytical investigation of Late Bronze Age mortars from various archaeological sites of Cyprus. We focus on petrographic observations of thin sections, scanning electron microscopy and energy dispersive X-ray microanalyses and we investigate the microstructure and texture of the samples and the chemical composition and interface of their binders. Results of powder X-ray diffraction analyses are also presented, alongside a series of measurements using mercury intrusion porosimetry and vacuum saturation, aiming to estimate the pore size distribution and the physical properties (i.e. open porosity and bulk density) of the specimens under investigation. We also report on tests carried out to assess the drilling resistance of the mortars using a novel, portable system. The results thoroughly confirm, for the first time, the earliest intentional use of crushed brick as an artificial hydraulic additive in lime mortars in Cyprus, in order to enhance their performance and longevity in the absence of natural pozzolanas.     

Wall Paintings from the Roman Emona (Ljubljana,Slovenia): Characterization of Mortar Layers and Pigments

This study concerns the investigation of mortar layers and pigments of wall paintings from the Roman town of Emona (Ljubljana, Slovenia). Fragments of wall paintings consist of up to three preserved mortar layers. The mineralogical–petrographic compositions of the mortars were determined by means of optical microscopy and FT–IR spectroscopy. The investigated samples were divided into several groups based on similar thicknesses of the mortar layer, the binder colour and the composition of an aggregate. Furthermore, the results of mercury intrusion porosimetry showed that mortar layers consisting of carbonate grains exhibited lower porosity with respect to layers with mainly silicate grains, which is attributed to the angular shapes of carbonate aggregate. This is in accordance with the drilling resistance measurement system test (DRMS), confirming that layers with angular carbonate grains are harder than those with addition of rounded silicate ones, due to the good packing effect. The wall paintings were mainly executed using the fresco technique, while for some details secco was used. The identified pigments were red and yellow ochre, green earth, Egyptian blue, carbon black and lime white; all of them belonged to the so‐called austere pigment, which is quite common in Roman wall paintings.     

Paper 6: Grouting Mortars for Fragmented Bricks and Repair Mortars for Tiles in the Archaeological Site Coudenberg

Abstract

Different grouting and repair mortars were developed and evaluated for the conservation and restoration of fragmented bricks in the walls and floors of the remaining cellars underneath the Aula Magna, the palace’s main banqueting hall, and to fill the lacunae and perform edge repairs of red and blue-grey ceramic floor tiles in the remaining cellars underneath the chapel of the former Palace of Coudenberg in Brussels, Belgium.

To prevent the deposition of lime bloom at the surface of the masonry and to achieve an acceptable colour match of the grout in harmony with the bricks of the Aula Magna, the effect of brick powder added to natural hydraulic lime was studied. The pozzolanic properties and colour match of several historic and modern powdered bricks were investigated. Surprisingly, ancient bricks do not seem to possess higher pozzolanic properties than the more modern ones, although it is supposed that they were fired at lower temperatures. Additional evidence for the pozzolanic reaction of the different brick powder materials was obtained from a simple visual observation of stored samples. After eight weeks all of the samples containing brick powders, fired at low and high temperatures, added to putty lime had hardened under water and were transformed into a remarkably tough material. These results are important, as modern bricks are readily available in large quantities and different colours, which are hence in favour of being used instead of historical material from the site.

For the repair of the ceramic floor tiles different mortars were investigated with mixtures containing talcum, stone or brick powder, pigments, and chalk added to an epoxy binder. The mortars were tested in the laboratory and in situ for their workability and resemblance with the historic floor tiles. The finished mortars showed excellent aesthetic properties with the tiles in situ and good properties to prevent further loss due to human interaction.     

The ancient pozzolanic mortars and concretes of <Emphasis Type="Italic">Heliocaminus</Emphasis> baths in Hadrian’s Villa (Tivoli,Italy)

The aim of this work is the physical and mineralogical-petrographic characterization of the mortars from the Baths with Heliocaminus, a special and unique architectural building in the complex of the Hadrian’s Villa in Tivoli. Thirty samples were investigated for composition and physical properties (density, porosity, water absorption, mechanical strength, particle size distribution of aggregate, etc.), representative of eight mortar groups: cubilia bedding mortar, brick bedding mortars, floor-coating and wall-coating bedding mortars, floor (rudus) and wall conglomerates (trullisatio), vault concretes, and lime plasters (arriccio). Physical parameters, together with the microscopic analysis and binder/aggregate ratio determined in three ways using image analysis (on thin sections and on specimens) and weight-data from dissolution of binder, have shown an interesting relationship between the physical-compositional characteristics and the function of mortars within the structure of the Heliocaminus baths. To identify the minerals and the reactant phases between binder and aggregate, as well as the hydraulic degree, selected samples were analyzed with x-ray powder diffraction, thermogravimetry, and differential scanning calorimetry techniques. The obtained results provide a close relation between pozzolanic characteristics and physical-mechanical properties of the mortars (i.e., punching strength index).     

Historical materials from the post-Cistercian abbey in Kamieniec Ząbkowicki (southwestern Poland)—application of mineralogical methods for identification of source of raw materials

In this paper, we use a set of methods applied for geosciences to reveal the provenance of raw materials and historical aspects of technology of lime production from the post-Cistercian church (southwestern Poland). Two types of building stones (mica schists and sandstones) and two groups of mortars, related with two different construction phases (Gothic and Baroque), were used for construction of the church façade. Principal difference between binding materials involves the presence of Mg-rich phase within Baroque mortars as a result of carbonation of a dolomitic lime whereas Gothic mortars are devoid of hydromagnesite. Mineral composition of the fillers of both mortars is similar, suggesting the same origin represented by local eluvium. Binders of studied mortars are composed of calcite and/or hydromagnesite and rich in lime lumps suggesting incomplete calcination. Studied mortars are weathered which is manifested by presence of gypsum. However, there is no evidence of commonly occurring Mg-rich secondary phases within Baroque mortar probably due to higher solubility of these salts comparing to gypsum. Mineralogical study combined with archeological and geological information enables us to indicate potential sources for the studied building materials. Metamorphic rocks, prevailing within the façade, come from abandoned quarries located in the closest vicinity of the church, whereas sandstones were acquired from the deposits located at a distance of tens of kilometers from the Kamieniec Z?bkowicki. Raw materials used for lime burning were gathered from Przeworno (Gothic mortars) and Z?oty Stok area (Baroque mortars) located approximately 25–30 and 12 km from studied church.