Characterization of building stones from the ancient Tyana aqueducts,Central Anatolia,Turkey: implications on the factors of deterioration processes

Many archaeological and historical monuments constructed by different civilizations over the last 5500 years can be observed in the Ni?de region located in central Anatolia. The Tyana aqueduct as a continuation of the Roman Pool is one such important historical monument. The aqueducts that carried the water of the Roman Pool to the ancient city of Tyana were constructed during the time of the Roman emperors Trajan, Hadrian and Marcus Aurelius Antoninus. Half of the total length of the aqueducts (3 km) is on the surface and the rest is buried. The engineering properties of the rocks used in such archaeological and historical buildings are very important in terms of conserving these structures for future generations. In this study, the geomechanical and geotechnical features of the Tyana aqueducts were investigated to understand the rock types, deterioration in the stones over time and problems originating from these features. Also, for restoration purposes, the ancient stone quarry areas for the aqueducts were identified, and the chemical, petrographical and geomechanical properties of fresh travertine blocks from these quarries were determined. The main rock type used as building stones in the aqueducts is Mio-Pliocene travertine. Laboratory studies were performed to determine the mineralogical, petrographic and petrophysical properties of the building stone samples. Fresh and used travertine samples were composed exclusively of calcite crystal. The results of chemical analyses were similar for fresh and used travertine samples. To determine the geomechanical properties of the travertines, dry unit weight, water absorption, effective porosity, P-wave velocity, Böhme abrasion test, capillary water absorption and uniaxial compressive strength experiments were conducted. In addition, Schmidt hammer hardness measurements were performed on site for the different levels and different textural characteristics of the belts on the travertines. According to the experimental data obtained, higher strength was displayed by samples with fine grains, massive texture and low porosity. The deterioration effects in most of the travertines used in the original structure are very low. In addition to human effects, the use of small stone dimensions (especially the stones used in belts as keystones) and the use of stone from the same quarry but with features that differ or are inferior are thought to be factors in the destruction of the Tyana aqueducts.     

Characteristics of carbonate building stones that influence the dry deposition of acidic gases

The behaviour of several porous carbonate building stones used in Spanish and English monuments was compared. Stones were exposed to urban and suburban environments and subjected to simulated SO₂ atmospheres in the laboratory. Physical properties that affect the transfer of moisture were determined before and after exposure, and related to the degree of reaction of the stones. The degree of reaction was determined by analysing the reaction products. Results showed that physical properties influenced the reactivity of the stones. These characteristics also changed as the stones weathered due to the different concentrations of impurities in the material. Moreover, stones with a high specific surface area and/or a deliquescent salt content may promote more NO_x dry deposition.     

Petrophysical characterization and durability aspects of tufa rocks at Kurkur Oasis,Western Desert,Egypt

Bulletin of Engineering Geology and the Environment - Various kinds of rocks can be used as building stones based on their durability, appearance, and availability. During many periods of times,...     

Durability of a sandstone used as a principal building and decorative material in ancient Abdera,Xanthi, N. Greece

Stones have been used as a construction material in Greece, since the 7th century B.C. Most of the public and other important buildings in ancient greek cities were made of stones. Various types of rocks have been used, from soft rock like travertine, soft sandstone, marl limestone, etc., to hard rocks like maarble, hard limestone, schist, etc. Some of these rocks, especially the soft ones, created problems of deterioration, through the time. One such a case, the deterioration of a soft sandstone used in Ancient Abdera, N. Greece, is examined in this paper. This sandstone is a molassic origin rock, used both as a building and decorative material since the antiquity. Sampling were made both from modern quarries (fresh rock) and the ancient settlement. The mineralogy, the granulometry, the physical and technical properties, the salt resistance and durability of the rock were examined in order to elucidate the possible causes of its deterioration in construction works. From the results obtained, it is concluded that the rock varies much in the field: in composition, in texture, and in coarseness. It consists of sand with remnants of rock fragments coming from the nearby metamorphic rocks of Rodope range. Petrographically the rock varies from lithic wacke (conglomerate, breaccia) (rock fragments >15%), to arkosic (feldspathic) wacke (feldspars>25%), to greywacke (clay>20%). According to its coarseness it varies from very coarse (mean grain size >4 mm) to very fine (grain size <0.2 mm). Its feldspars are in different stage of weathering, from intact to completely kaolinized. The matrix material, in most cases is more than 15% (>15%) and consists mainly of silica and clay in different proportions; ferrous oxides and/or hydroxides are present too. The CaCO₃ is usually low or non existant. The rock porosity is medium to high. The physical and technical properties of the rock in the field varies according to its mineralogy, texture (coarseness, matrix material, porosity), water content, etc. In general, the coarse grained members, with low clay content, low porosity and low water content are the most hard and durable. The water content places an important role in the strength of the rock mostly in clay reach members. The amount of matrix material, the porosity, and the strength of the rock decrease as its grain size (coarseness) increase. The main cause of the rock deterioration, in the construction sites is considered to be the water absorption and the salt crystallization (sea and/or ground water salts) near or under the rock surface. This is due to high clay content and the weak matrix material. Consequently, when the rock is far from the sea and/or from the foundation of the structure or in dry environments, it is quite durable with no problem of deterioration. Problems are created when the rock has been used in structures near the sea or in foundation. The possible remedial measures to be taken, in the ancient sites, are the protection of the rock from ground and/or sea water absorption and the related salts, by sheltering, water repelant coatings, and/or stabilizing agents.     

激发剂在石膏胶凝材料中的应用

石膏胶凝材料是以石膏为主要原料复合其他矿物掺合料用于生产砌块等建筑材料的一种新型石膏资源化利用的材料。石膏胶凝材料体系通常加入适量的矿物掺合料,并且大量使用石膏产品,这样以来在改善石膏胶凝材料制品性能的同时,可以大量使用工业副产品。但是,在没有碱性激发剂的情况下,石膏制品的强度和耐久性都相对较差。该文研究总结了激发剂对石膏制品性质的影响,重点总结了化学激发剂硫酸盐和氯盐对石膏体系的性能影响。通过研究表明,化学激发剂的适量加入可以有效地改善石膏体系制品的物理力学性能和耐久性。     

Building materials as intrinsic sources of sulphate: a hidden face of salt weathering of historical monuments investigated through multi-isotope tracing (B, O, S)

Sulphate neoformation is a major factor of degradation of stone monuments. Boron, sulphur and oxygen isotope signatures were investigated for five French historical monuments (Bourges, Chartres and Marseille cathedrals, Chenonceau castle, and Versailles garden statues) to investigate the role of intrinsic sulphate sources (gypsum plasters and mortars) in stone degradation, compared to the influence of extrinsic sources such as atmospheric pollution. Gypsum plasters and gypsum-containing mortars fall systematically in the δ³⁴S and δ¹⁸O range of Paris Basin Eocene evaporites indicating the origin of the raw materials (so-called "Paris plaster"). Black crusts show the typical S and O isotope signatures observed elsewhere in Europe that can be attributed to atmospheric pollution, together with a marine component for Marseille. Boron isotopes for black crusts indicate coal combustion as principal boron source. Mortar isotope compositions discriminate three types, one similar to gypsum plasters, one strongly depleted in ³⁴S, attributed to pyrite oxidation, and a third one close to atmospheric sulphates. The isotopic composition of sulphates and boron of most degraded building stones of the different monuments is well explained by the identified sulphate sources. In several cases (in particular for Chenonceau and Bourges, to some extent for Chartres), the impact of gypsum plaster as building and restoration material on the degradation of the stones in its vicinity was clearly demonstrated. The study illustrates the usefulness of multi-isotope studies to investigate stone degradation factors, as the combination of several isotope systematics increases the discriminatory power of isotope studies with respect to contaminant sources.     

An introduction to the karst geomorphology of the Bisetun–Taqe Bostan historical region (northeast Kermanshah,Iran) with special emphasis on karst development as a serious threat for the UNESCO World Heritage Site

The Bisetun–Taqe Bostan crushed carbonate massif (northeast of Kermanshah City) is a historical region that includes several famous monuments. Several types of karst features, the surface kind especially, have been developed in the area because of high rainfall in the area, tectonic crushing and high purity of the rocks. The field survey showed that the major karst features are karren, including rillenkarren, trittkarren, and solution runnels. Some of the monument stones by it have been deteriorating. Cavities and caves, solution dolines, and karstic springs are other observed karstic features in the area. Cavities and caves present mostly at intersections of shear faults or joint sets, which are considered the main location of water seepage throughout the limestone mass. Dolines in the region can be divided into two groups including solution and collapse dolines. The first group involves deep and large dolines without surface deposit cover, whereas the second group includes shallow dolines with smaller sizes covered by soil layers. Dolines are not problematic for the monuments because of their relatively high distance from them. There are a number of karstic springs in the study area; the Bisetun and Taq-e Bostan springs are the most important among them. Both springs discharge at a fault surface in vicinity of the monuments. As a part of the present study, deterioration occurring in the monuments due to the karst development was investigated. Moreover, some physical and chemical preservation methods were proposed to protect the monuments.

     

NaCl crystallization in restoration plasters

Salt crystallization is one of the most recurrent causes of damage in building materials. In this paper a study of NaCl crystallization in restoration plasters is presented. The morphology of the salt crystals, the location of salt crystallization and the decay patterns are investigated and related to the properties of the plaster and of the substrate/plaster combination. The research has been part of a European research program COMPASS.Based on ESEM observations from laboratory and field samples it is shown that moisture transport is one of the most important factors determining the location of salt crystallization. In particular, the presence of a water repellent strongly influences the location of salt accumulation. Depending on the effectiveness of the water repellent, salt will accumulate either at the substrate/plaster interface (salt blocking plasters) or in the inner layer of the plaster (salt accumulating plasters). The transport can be influenced by the pore system and by chemical admixtures like water repellents. Furthermore, it is discussed that salt is usually not found in cracks. It is suggested that a mechanism of differential dilation of zones with high and low salt content may be responsible for the damage.     

Water absorption and dehydration of natural stones versus time

Physical, chemical and mechanical properties of natural stones play an important role on deciding their application area as a building stone. In this study, water absorption and dehydration time of five different types of natural stones (marble, limestone, travertine, onyx and granite) were comparatively examined. Porosity, dry unit weight, wet unit weight, water absorption ratio and chemical analyses of the rock samples were also determined. In the light of the obtained experimental results, it was found that MgO content as the chemical property, and porosity as the physical property played a major role in the water absorption capacity and dehydration time of the studied natural stones. Basing on some observations made in this study, it was also emphasized that common standards involving the determination of water absorption coefficient by the capillarity test in rocks should be re-evaluated.     

Modelling the compressive mechanical behaviour of granite and sandstone historical building stones

Building stones, particularly sandstone and granite, are very important in the building elements of Portugal’s historical and cultural heritage. Experimental research, based on uniaxial compressive tests, was carried out on selected representative samples of lithotypes of rocks used in historic built heritage, with a view to evaluating the compressive mechanical behaviour of different building stones. The results showed that porosity plays a central role in the compressive behaviour of granites and sandstones. As porosity can be evaluated in field conditions with non-destructive tests it was decided to derive an analytical model to predict compressive behaviour based on the knowledge of porosity of the building stones. A cubic polynomial function was adopted to describe the pre-peak regime under compression to implement the model. Furthermore, a statistical correlation between mechanical and porosity data had to be defined. Good agreement between experimental and analytical compressive stress-strain diagrams, from which the mechanical properties like compressive strength and modulus of elasticity can be derived, was achieved.     

Investigation of engineering properties for usability of Lefke stone (Osmaneli/Bilecik) as building stone

Lefke stone is a sandstone that has been widely used in mosques, madrasas, churches, and houses as building stone. The geological features and engineering properties of Lefke stone outcropped in the southern part of Osmaneli/Bilecik were investigated in field and laboratory studies. Samples acquired during the fieldwork were tested to determine the physical, mechanical, durability, and hygrothermal properties in the laboratory. The mean physico-mechanical properties of Lefke stone yielded apparent density of 2.38 g/cm³, specific gravity of 2.68 g/cm³, total porosity of 11.26%, 2.93% water absorption by weight, uniaxial compressive strength of 94 MPa, flexure strength of 11.45 MPa, a 3.90 MPa point load strength, 4.5–5 Mohs hardness, and field Schmidt hammer rebound value of 36. According to durability tests, Lefke stone is resistant to CaCl₂ salt mist but has low resistance to SO₂ aging. Salt crystals placed in the discontinuities of the rock caused slight crack growth. The stone’s resistance to crystallization of sodium sulphate salt is low, and an increase in the volume of salts crystallized in the rock results in low corner strengths. A capillary water-absorption value of 0.0016 kg/m².h places Lefke stone into the category of very low water absorption capacity and permeability. The water vapor diffusion resistance factor (μ) less than 1 indicates that the sandstone has high breathability. Its performance in historical buildings, field observations, and values obtained through laboratory tests confirm that Lefke sandstone can be used as a building stone.

     

A comparative study of hygroscopic moisture content,electrical conductivity and ion chromatography for salt assessment in plasters of historical buildings

It has long been known that highly soluble salts or hydrate-forming salts can damage porous building material. There is a real challenge to provide salt assessment in compliance with good monuments diagnosis and restoration practices. The salts present in the masonry can be analysed qualitatively and quantitatively by means of several techniques. Nowadays, the standard analytical equipment as ion chromatography (IC) found in several laboratories is a reliable method for analysing a large variety of anions and cations in solutions (or building materials water extracts), in order to meet international standards and regulations. However, preliminary study and diagnosis of soluble salt present in monuments do not necessarily require such a precise (SD < 5%) and sensitive (ppm or ppb range) analyses. Some simple-to-use techniques, such as hygroscopic moisture content (HMC) and electrical conductivity (EC) of extracted salt solutions, are widely in use to provide indications on the presence of salts.This paper presents a comparison of salt assessment obtained by IC, HMC and EC methods, and provides the domain of their application to specific questions linked to the damaged building diagnosis and preservation.The comparison of the results obtained by IC, EC and HMC analyses highlights the limits of the EC method in providing quantitative information on soluble salt content. The EC technique seems to require some cautions when used for materials containing other high soluble phases such as portlandite. On the other hand, the HMC technique seems to be very useful in the field of historical masonry investigation since it can provide reliable semi-quantitative distribution of hygroscopic salts.     

吴哥古迹保护修复的实践与理念发展脉络

柬埔寨吴哥古迹是人类历史上辉煌的遗迹,是人类共同的文化遗产,同时也是国际古迹保护修复的实践与理念的反映。其古迹保护修复理念及实践方法一直与国际上古迹保护修复的理念及方法同步。从最早作为法国殖民地,以西方的遗产保护理念对古迹进行修复;到新时期各国和国际组织发起的保护吴哥古迹国际行动中所运用的新理念,新技术,无一不反映各个国家在不同文化背景下的古迹保护修复方法和理念。他山之石,可以攻玉,通过梳理历史上吴哥古迹保护修复的实践与理念的发展,展示东西方文化古迹遗产的保护哲学,为国内的遗产保护提供参考与借鉴。     

Methods for porosity measurement in lime-based mortars

Porosity is one of the most common determined physical properties of building materials mainly because of its influence on important properties such as strength and durability. Porosity especially in lime-based mortars occupies an important volume. The heterogeneity as well as ageing effect often found in these mortars that have been used for the construction of monuments and historic buildings, make porosity a difficult property to measure. In the paper the porosity of old lime-based mortars is estimated using four well-known techniques. The advantages and restrictions of each method are discussed. The porosity values differ according to the methodology followed. The type of information gained by each method could give valuable data for the material’s quality.     

Prediction of elastic and acoustic behaviors of calcarenite used for construction of historical monuments of Rabat,Morocco

Natural materials (e.g. rocks and soils) are porous media, whose microstructures present a wide diversity. They generally consist of a heterogeneous solid phase and a porous phase which may be fully or partially saturated with one or more fluids. The prediction of elastic and acoustic properties of porous materials is very important in many fields, such as physics of rocks, reservoir geophysics, civil engineering, construction field and study of the behavior of historical monuments. The aim of this work is to predict the elastic and acoustic behaviors of isotropic porous materials of a solid matrix containing dry, saturated and partially saturated spherical pores. For this, a homogenization technique based on the Mori–Tanaka model is presented to connect the elastic and acoustic properties to porosity and degree of water saturation. Non-destructive ultrasonic technique is used to determine the elastic properties from measurements of P-wave velocities. The results obtained show the influence of porosity and degree of water saturation on the effective properties. The various predictions of Mori–Tanaka model are then compared with experimental results for the elastic and acoustic properties of calcarenite.     

陕西勉略宁元古宙海相火山岩成岩构造环境及演化

勉略宁元古宙海相火山岩，划分为四个火山岩带，通过对火山岩带地球化学的研究，旨在揭示火山岩带的成岩环境，追踪火山作用的演化历史。研究认为勉略宁元古宙海相火山岩发生发展于裂陷海盆中，经历了扩张－裂陷、叠缩－消减和碰撞－造山三个演化阶段。南带和中带火山岩分别形成于扩张－裂陷的早期和晚期，其中罗家山火山岩产于洋岛环境；北带火山岩为叠缩－消减的岛弧环境；在碰撞－造山过程中产于不同环境的火山岩带叠缩、构造拼贴作为添加地体拼合在扬子板块西北缘     

沈阳福陵古建筑石受损分析及保护

本文主要对沈阳福陵中古建筑石材受损形式进行了研究,同时对其受损原因进行了探讨,原因主要是气候和地质变化对其影响;有些古建筑石材受到物理和化学综合作用。对古建筑石材保护提出几点建议和措施。对古建筑石材受损研究和保护是很重要的一件大事,也是对历史文化的保护和传承。     

Geo-ecological investigations in the area of comune di grosio (Northern Italy)

The paper gives consideration to the experience of carrying out a short-term (one-moth) geoecological investigation in the territory of Comune di Grosio (Northern Italy). The investigations were aimed at: estimating the geoecological conditions of the given territory and building up cartographic models showing the character, degree and scale of pollution of surface waters, soil, bottom sediments and vegetation; geochemical estimate of water resources used for engineering and drinking water supply; compiling a schematic map of the location of architectural and historical monuments, and their inventory; estimating the decorative and building properties of feldspar.     

A preliminary study on the conservation and polishing performance of Sanliurfa limestones as a traditional building material

Sanliurfa limestones have been used as building materials from antiquity to current day (e.g., Gobeklitepe temple B.P. 14,000, Bazda underground quarries B.P. 3000, Harran castle B.P. 3000, etc.). These antique structures are listed within the United Nations Educational, Scientific and Cultural Organization (UNESCO)’s World Heritage List. However, the stones were used in these structures without any protection, and atmospheric conditions (precipitation, acid rain, temperature changes, etc.) cause damage to these stones over time, such as strength loss, abrasion, and discoloring. The damage can lead to the collapse of precious historical structures, or may require costly restoration. In this study, Sanliurfa limestone was investigated with respect to conservation using polish insulation (polysiloxane, lithium silicate, and varnish), appearance performance by polishing, and potential usage in the marble industry. The results revealed that conservatives could maintain up to 92 % of the unconfined compressive strength (UCS) of the natural stone and reduced acid abrasion to 0.5 % of the original weight. The stone gained a bright appearance after polishing, especially by lithium silicate. Thus, it can be stated that it is possible to recover or prolong the lifetime of the monuments that were constructed using Sanliurfa limestone, and this limestone may have great industrial potential as marble stone.     

Relations between petrography and the aggregate properties of icelandic rocks

Research work and field experience show that in Iceland aggregate properties and petrography are usually closely related. All rocks are volcanic, and the main types are basalt, rhyolite and hyaloclastite (consolidated tuffs). Unaltered basalt has in most respects high qualities, but impact and abrasion strength, durability and other propertis diminish rapidly with increased alteration. Porosity has an influence on the wear of road surfaces, but in other relations, porous and fresh basalt lava is advisable. Rhyolite can cause damage in concrete by alkali-aggregate reaction, and overall, both rhyolite and hyaloclastite have worse properties than basalt.