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.     

Multi‐analytical Studies of the Lime Mortars from the Yanxi Hall in the Yangxin Palace of the Palace Museum (Beijing)

For centuries, the architecture of the Palace Museum represented the highest standard of Chinese architecture. The Yangxin Palace of the Palace Museum consisted of 18 masonry buildings built using bricks, wood, roof tiles and various mortars. In 2016, a five‐year project was initiated to work on the maintenance and restoration of the Yangxin Palace buildings. The characterization of the construction materials has become of primary importance, in order to obtain information about the raw ingredients and building technology of the mortars, and the history of possible previous restorations. In this paper, 12 different samples representing three types of mortar‐based materials—namely, jointing mortars between the bricks on the wall, and surface plasters as well as mortars used on the roof—were collected for analysis from the Yanxi Hall of the Yangxin Palace. Analysis into the composition, grain‐size distribution, organic and fibre additives and testing of the mortar density and water absorption were performed. Starch, protein and plant fibres were identified in some of the samples. Brucite, mullite and ettringite were detected within most mortars on the roof, possibly originating from the furnace slag added into the raw materials for restoration purposes. The analytical results will serve as a critical reference for the maintenance and restoration of the buildings in the Yangxin Palace.     

Historical Mortars from the Fortified Upper Town of Eivissa (Balearic Islands,Spain)

Samples of mortars and stone of Portal de ses Taules from the Renaissance city walls of Eivissa (16th century) were characterized using thermal analysis— thermogravimetry and derivative thermogravimetry (DTG)—x-ray diffractometry, and scanning electron microscopy. The granulometric fraction of particle size <63 μm was selected as representative of the binder, while the fraction 0.5–1 mm was taken as representative of the aggregate in order to characterize mortar samples. The results show that local materials were used. Lime was the main component of most of the samples tested. Thermal analysis revealed the hydraulic nature of the lime mortars. High amounts of sodium chloride were found in the samples analysed.     

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.     

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.     

Characterization of pozzolanic lime mortars used as filling material in shaped grooves for restoring member connections in ancient monuments

This article presents a set of mechanical characteristics for a pozzolanic mortar consisting of hydrated lime and metakaolin, which is used as filler between metallic connectors and marble blocks during restoration activities of ancient monuments in Greece. Mechanical properties include the uniaxial and triaxial compressive strength, the indirect tensile strength, the bending strength, the elastic modulus and Poisson’s ratio, and a shear failure criterion. Cored cylindrical specimens are used for determining the uniaxial and triaxial compressive behavior and the indirect tensile strength of the mortar, thus ensuring the repeatability of the experimental results. The triaxial tests indicated a plastic behavior of the mortars under study, enabling them to perform well in conditions of high shear forces. Calcite and hydraulic components formed in the setting procedure contributed to the plasticity of the final mortar. The mechanical properties that were developed can be utilized to model material behavior and failure under conditions of confined or triaxial loading. The development of a shear failure criterion for a pozzolanic mortar is a substantial accomplishment that has not been previously reported in the international literature.     

Chemical and Microscopic Study of Masonry Mortar in Ancient Pagodas in East China

Ancient mortars played a crucial role in the construction of historical architectures due to their physical and chemical compatibility with traditional building materials such as stones and bricks. Therefore, the analysis and optimization of the ancient mortar formula are significant in the restoration and preservation of historical sites. In this work, 20 mortar samples selected from five ancient stone pagodas in Zhejiang Province, China, were analyzed. The results showed that mud, lime-soil mortar, lime-sand mortar, and lime-gypsum mortar were used as binders in these pagodas. The Ca(OH)₂/aggregate ratio ranging from 0.3 to 2.7 was usually used to prepare lime mortar. Protein and polysaccharide were also found in some samples.     

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 5: Historic Mortars from the Coudenberg Archaeological Site: Characterization and Source of Raw Materials

Abstract

The characterization of historic mortars by means of a concise methodology of material analyses can provide crucial information with regard to the origin of the raw materials and the ancient mortar technology. For the analysis of the historic mortars of the Coudenberg archaeological site, the methodology consists of optical and scanning electron microscopy, simultaneous thermal analysis, and an acidic treatment. These analyses were carried out on a total of seventeen samples lifted from various areas in the site, in function of the building chronology resulting from a historic built investigation. The type of binder and aggregate as well as their volumetric ratio were determined.

Both binder and aggregate present distinctive features, which made it possible to identify the probable geological provenance of the raw materials. The observations are verified with available historical records regarding the construction of the main banqueting hall — the Aula Magna — and the use of raw materials such as limestone and sand for the production of lime and construction purposes.     

Hydraulic structures of the Roman Mithraeum house in Augusta emerita, Spain

This paper deals with some of the hydraulic structures of Augusta Emerita (Mérida, Spain), specifically those found in the Mithraeum House. In particular, we describe and characterise the hydraulic mortars and coatings of the viridarium water channel. The recipient of the channel was covered with two hydraulic mortars and a finishing coating. Hydrated lime was used as binder. Calcite grains with different morphology have been observed in the mortars studied. The siliceous aggregate was composed of quartz, mica and feldspars. Ceramic fragments, which were added to the mortar to improve its hydraulic properties, were composed of quartz, mica, iron oxides, anorthite and an amorphous phase; aluminium-iron silicates were used as raw materials for their manufacture. We discuss the interactions between the hydrated lime and the surface of the ceramics in the mortars.     

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 mortars dating from OSL signals of fine grain fraction enriched in quartz

In the last years the mortar dating through Optically Stimulated Luminescence (OSL) techniques has become a viable support for chronological estimations (date of construction or restoration episodes) of historical buildings. However, the dating of mortar has still open issues mainly regarding the assessment of the bleaching degree of quartz, the analysis of the OSL processes for this type of samples and the need to do appropriate tests for the most correct evaluation of the equivalent dose. This paper discusses the results obtained by OSL dating (blue diode stimulation) on the polymineral fine grain phase, enriched in quartz, extracted from lime mortar samples collected from different sites. Thermal transfer effects, through the behaviour of Equivalent Dose (ED) and recovery tests, degree and time of bleaching were studied. For each mortar sample the adjacent brick was collected; in some cases, sampling of the bricks bracketing a mortar layer was a possibility, thus obtaining a direct comparison with the standard thermoluminescence (TL) dating on the bricks. The results obtained show, for this set of samples, the possibility of dating the mortars through the use of the fine grain fraction provided of a suitable chemical-physical preparation procedure and the verification of the bleaching conditions.     

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.     

荆州古城勒名砖与"物勒工名"

本在对多年来搜集的26l例散见于荆州现存古城墙上的勒名砖整理、分类的基础上,对其中有代表性的勒名砖进行考证说明,并附有列表及典型砖例的实物拓片,还根据实物材料对荆州有砖城以来的筑城史及城砖的“物勒工名”制度的发展轨迹进行了初步探讨以期有助于加深对荆州古城的认识。     

A Multidisciplinary Approach for the Archaeometric Study of Pozzolanic Aggregate in Roman Mortars: The Case of Villa dei Quintili (Rome,Italy)

This contribution focuses on the study of historical mortars from a Roman archaeological site known as Villa dei Quintili, a monumental villa located in the south‐eastern part of Rome (Italy). The study was carried out on 38 mortar samples, collected from several edifices within the complex. A multi‐analytical approach, including polarized optical microscopy, scanning electron microscopy coupled with energy‐dispersive system and laser ablation inductively coupled plasma mass spectrometry, was used to analyse the pozzolanic material used for the preparation of mortars. Data obtained on both major and trace elements were compared with the compositions of Pozzolana Rossa, Pozzolana Nera and Pozzolanella samples from the Alban Hills volcanic district, collected from a historic quarry nearby, as well as with literature data. The results of such a multidisciplinary approach allowed us to recognize the use of all three pozzolan types for the aggregate fraction of examined mortars from the Villa dei Quintili.     

Characterisation of archaeological mortars and plasters from kyme (Turkey)

The present study focuses on the compositional characterisation of Roman, proto-Byzantine and Medieval mortars, sampled in the archaeological site of Kyme (Turkey), an Aeolian city, founded in the middle of the XI century BC by Greek populations. The mortars were studied through elemental (SEM-EDS, XRF), mineralogical (XRPD, De Astis calcimeter) and petrographic (polarised optical microscopy) analysis. The comparison between the samples allowed us to emphasise compositional differences within mortars of the same historical period.In particular, we detected the prevalent use of cocciopesto, which was used as a pozzolanic additive to create hydraulic mortars in the Roman and Byzantine period. The cocciopesto was used to improve the technological properties of an initially slaked lime. Furthermore, compositional similarities allowed us to attribute an unknown sample to the Roman period. Our study also pointed out the fact that the lower quality mortars belonged to the Medieval period. As a matter of fact, the most friable sample belonging to the Middle Ages turned out to be a mixture of clay, lime and volcanic sand.     

Mineralogical and Mechanical Properties of Masonry and Mortars of the Lucknow Monuments Circa the 18th Century

The Lucknow monuments of the 18th century are large masonry structures built using thin burnt-clay bricks (Lakhauri) and lime-crushed brick aggregate (surkhi) mortars. Investigations were carried out to characterize the engineering properties of old masonry materials and new mortars being used for renovation work. Mechanical properties of reclaimed Lakhauri bricks were found comparable to good quality contemporary bricks of the region. Moreover, X-ray diffraction (XRD) and scanning electron microscopy–energy dispersive X-ray spectrometry (SEM-EDS) analyses indicated that mineralogical composition is not too different, except for few minerals. The lime-surkhi mortar used in old masonry work was found to be lime-rich with binder to aggregate ratio of approximately 1:2 to 3 by volume. The renovation mortar had poor hydraulic property as compared to old mortars indicated by thermal gravimetric analysis–differential thermal analysis (TGA-DTA) analyses. The compressive behavior of multi-wythe recreated Lakhauri masonry prisms was characterized with low compressive strength, low modulus, and significant deformability which result in lower stress demands imposed on the structural assemblages by various environmental forces.     

Dimensional variations of Roman masonry subjected to wetting-drying cycles

Abstract

Many Roman monuments made of opus caementicium are subjected to wetting and drying phenomena caused by water or/and humidity from the ground. The action of water impregnation on the hypothetical dimensional changes in this Roman concrete has not been considered in the literature and no experimental data are available.

The purpose of this work was the evaluation of the effect of wetting and drying cycles in a number of cores taken from an ancient Roman monument (Domus Tiberiana in the Palatine, Rome). The concrete samples were made of a pozzolanic mortar with large pieces of tuff, marble and bricks.

In spite of some differences in their composition, the behaviour of the cores was similar and, generally, quite constant during the experimental cycles. On the average, the length variation was about 3–4%,or 3–4mm for each metre and, when related to high structural walls and monuments, the possible dimensional changes were quite impressive.     

桃渚城城墙病害初步调研与保护对策探讨

临海桃渚城建于明代,是浙江保存最完好的抗倭卫所城址,全国重点文物保护单位。通过对桃渚城的现存状况进行调查分析可知,城墙目前存在局部垮塌、鼓闪、灰浆流失等病害,其本身的构造缺陷加上降雨和植物生长的共同作用是病害的主要成因。这类问题在东南沿海地区的古城墙中具有一定普遍性。针对这些病害以及桃渚城的构造特点,结合国内一些城墙保护的工程实例,提出桃渚城的保护策略:加强墙体的结构稳定性、加固墙芯填土、增设墙顶防水措施、及时疏改威胁本体安全的植物,可为后续以及同类城墙的保护工作提供参考。     

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。