In Situ Flat-Jack Testing of Traditional Masonry Walls: Case Study of the Old City Center of Coimbra,Portugal

Single and double flat-jack tests are presently used widely for assessing the mechanical characteristics of stone masonry. This technique remains as one of the most versatile in situ test procedure for the estimation of the main mechanical properties of masonry walls. Nevertheless their application is still controversial due to the difficulty of accepting in some cases the results as reliable. This article presents and discusses the results of an experimental campaign resorting to flat-jack technique carried out with the scope of the rehabilitation process of the historical city center of Coimbra.     

劣化石刻表层生物矿化加固材料的探索性研究

许多濒危石质文物表层劣化现象严重。但是,以往使用的表层加固材料很难令人满意,探索新的疏松岩石表层加固材料已是当务之急。由于天然生物矿化物耐候性优越,与基底岩石相容性良好,具有较好的加固作用,本工作依据生物矿化的原理,以不同生物大分子溶液作为有机模板,分别控制草酸钙、磷灰石和碳酸钙过饱和溶液于室温下在疏松岩石仿制样品的表层及孔隙内结晶生长。通过抗压强度、表面硬度和耐水浸泡等试验进行了加固效果评价,以考察仿生物矿化材料对含钙疏松岩石的加固能力。实验结果表明,仿生合成的生物矿化材料均具有一定的加固效果,其中以磷灰石仿生矿化材料的加固强度最大,以硫酸软骨素为模板的加固效果为佳。并且,在考察的3种加固方式中,以"直接混合"的加固强度更好,以"表面渗透"的耐水浸泡能力更强。本工作为开发濒危石质文物表层加固材料提供了新的思路。     

Assessment Techniques for Studying the Effects of Fire on Stone Materials: A Literature Review

ABSTRACT

Fire is one of the most severe threats to stone applied in civil engineering and architecture. In most cases, its effects are irreversible and have long-lasting repercussions. In addition to aesthetic alterations, fire can also induce important mineral-chemical, physical, and mechanical changes in stone. Research concerning the effects of fire on stone materials in recent decades has been providing valuable knowledge to inform present and future conservation and restoration actions. In this literature review, the properties and techniques used for studying the effects of fire on stone materials are appraised, summarized, and compiled. A comprehensive and practical overview of those effects is also given. Open porosity and P-wave ultrasonic velocity are the physical and mechanical properties that have been studied most. Other frequently researched areas include chemical-mineralogical changes, color, density, water absorption, uniaxial compressive strength, and modulus of elasticity are also very frequently investigated.     

Experimental characterization of the constitutive materials composing an old masonry vaulted tunnel of the Paris subway system

A significant proportion of the Paris metro tunnels comprise a masonry vault built out of stone blocks and mortar joints, and sidewalls and slabs made of unreinforced concrete. In order to provide the necessary data for future structural evaluation, an extensive laboratory testing programme has been conducted to characterize the materials of the tunnel separately, i.e., mortar, stone, and concrete. The tests, carried out on specimens taken from cores extracted from a 1930s tunnel, enabled to determine the mechanical properties, including direct tensile, shear strength, and mode I fracture energy, as well as the properties of the stone-mortar interface. Results show that the masonry mortar joints could reach 10 cm in width, and that blocks of stone varied in composition and porosity, thus producing a wide range of mechanical properties. The concrete was composed of large-sized aggregates and showed low stiffness and strength. Based on these experimental results, ratios between mechanical characteristics are hereby proposed. Perspectives on the use of this experimental data in a finite element model are then discussed.     

Rubble Stone Masonry Walls Strengthened by Three-Dimensional Steel Ties and Textile-Reinforced Mortar Render,Under Compression and Shear Loads

This article addresses the results of a structural strengthening solution for rubble stone masonry walls. The strengthening includes inserting three-dimensional steel ties across the thickness of the walls and a 30-mm layer of air-lime and cement mortar render reinforced with glass fiber mesh (textile-reinforced mortar), on both sides of the wall. The strengthening solution was found to be efficient for rehabilitating ancient rubble stone masonry walls due to the “three-dimensional” confinement, provided by the steel wires, by offsetting the low cohesive capacity of the mortar used in the walls and thus improving the mechanical resistance and delaying the collapse mechanisms. This study is part of an experimental research program carried out in Universidade Nova de Lisboa, to evaluate structural strengthening solutions for ancient rubble stone masonry buildings. To this end, three specimens of rubble stone masonry walls without strengthening (unreinforced masonry) and other three, with the mentioned strengthening solution, were subjected to compression and shear load tests. Building materials were also tested in order to characterize physical, chemical and mechanical properties.     

Raw material quality and Oldowan hominin toolstone preferences: evidence from Kanjera South,Kenya

The role of raw material quality in Oldowan technology has not been fully explored. There are numerous studies suggesting Oldowan hominins preferred certain types of stone for artifact manufacture. Previous studies of the artifact assemblage from the early Pliocene Oldowan locality of Kanjera South (South Rachuonyo District, Kenya) show that raw material selection and transport was an important aspect of Late Pliocene hominin adaptations. Yet the exact properties of stones that hominins were selecting remain enigmatic. Two potentially important features of artifact raw material are durability and fracture predictability. We investigate fracture predictability through mechanical tests of stone and investigations of the affect of stone properties on fracture patterns in archaeological collections. We investigate stone durability with actualistic studies of edge attrition combined with further mechanical tests of various lithologies. Oldowan hominins at Kanjera appear to have selected raw materials based on their durability. The ability for a stone to fracture consistently does not appear to be as important in hominin toolstone preference as previously assumed. Hominins that produced the assemblages at Kanjera South appear to have incorporated an extensive understanding of various attributes of raw material in the transport and production of stone artifacts. When combined with previous research on the transport patterns at Kanjera, the results of this study provide evidence for a more complex raw material acquisition strategy than has previously been suggested for Late Pliocene Oldowan hominins.     

超声波技术在大佛寺石窟石质保护中的应用

介绍超声波探测在石质文物风化评价、化学加固效果评价及其裂隙研究方面的应用,并将其结果与目前常用的方法进行了比较。     

露天石质文物的风化和加固保护探讨

探讨了石质物风化的诸因素,认为主要来源于石材原料、物理因素、化学因素、生物因素和人为破坏等儿个方面,阐述了目前用于石质物加固保护的无机加固剂、有机加固剂的特点、应用及其加固技术,该工作对石质物加固保护具有指导意义。     

石质文物表面防护中的问题和新材料

野外的大型石质物暴露在自然界的风化环境中,近代环境污染和酸雨使侵蚀更加严重,已有许多防护材料用于石质物的防护,本分析了目前防护材料,特别是憎水性有机高分子防护材料在使用中存在的问题,并初步探索了使用新的生物无机防护材料的可能性。     

抗钻强度在文物加固保护中的应用

抗钻强度测试是一种极微小破坏性的强度测试方法,特别适合于物保护中加固强度及加固剂渗透深度的测定。通过用有机氟材料对几种不同材质物(石质、砖或陶质、土质)在实验室和现场加固强度及渗透深度的测试,并与抗压强度进行比较,结果表明抗钻强度是一种有效的加固强度表征方法,特别适合于物的现场保护应用。     

明祖陵石刻加固保护竣工报告

本介绍了明祖陵石刻的保存现状,以及对残损石刻的修复、加固、保护方法,并对明祖陵石刻的风化原因进行了分析。     

石窟造像防风化加固材料探讨

石窟造像文物具有不可再生性,因此对其保护加固材料的要求非常苛刻,除需具有很好的粘连性、渗透性、透气性、耐候性、疏水性和化学稳定性外,还需具有一定再处理性,且对石窟造像本身无副作用.本文通过对石质文物防风化加固保护材料的梳理,分析了各类保护材料的优缺点和适用性,为我国石窟造像防风化加固保护设计、施工材料选择和应用提供基础资料.     

Effect of heat treatment on siliceous rocks used in prehistoric lithic technology

Stone tool manufacture by many prehistoric and recent societies was characterized by deliberate heating of fine grained siliceous rocks to improve their flaking properties. Extensive mechanical testing of heated and unheated cryptocrystalline and macrocrystalline quartz lithologies has shown that thermal treatment causes a consistent marked reduction in fracture toughness. This mechanical property can be used as an objective measurement of the flaking qualities of stone materials, and a reliable criterion for the recognition of intentionally heated artefacts in the archaeological record. X-ray diffraction studies and scanning electron microscopy have demonstrated that the change in fracture toughness with heating is the result of recrystallization. The poorly ordered, strongly interlocking cryptocrystalline fabric of the unheated samples becomes more equigranular and better crystallized with thermal treatment. As a consequence, fractures propagate more readily in heated samples, accounting for their better flaking properties.     

The origins of lithic projectile point technology: evidence from Africa,the Levant,and Europe

Projectile weaponry is a human cultural universal, but its origins and antiquity remain poorly understood. Stone- and bone-tipped projectile weapons have long been treated as emergent features of the "Upper Paleolithic" behavioral revolution. Recently it has been proposed that projectile technology was in widespread use among Homo sapiens populations in Africa during Middle Stone Age (MSA) times. One obstacle to researching the origins of projectile point technology is that the criteria archaeologists employ for recognizing plausible and implausible stone projectile points are largely subjective (overall tool shape, microwear traces). Tip cross-sectional area (TCSA) is a ballistically significant dimension that works well at discriminating North American stone projectile points (spearthrower dart tips and arrowheads) from spear points. This paper compares the TCSA values of ethnographic North American stone projectile points to hypothetical Middle and Upper Paleolithic stone projectile points from Africa, the Levant, and Europe. The results of this comparison do not support the hypothesis of widespread use of stone-tipped projectiles in Africa, the Levant, or Europe prior to 40 Ka. In the New World and in Australia, where we have the richest ethnographic record of stone projectile point use, these implements are largely employed in big-game hunting and in warfare. One or both of these factors may have played a role in the widespread adoption of stone projectile point technology after 40 Ka.     

Multiple Optima in Hoabinhian flaked stone artefact palaeoeconomics and palaeoecology at two archaeological sites in Northwest Thailand

High resolution analyses of flaked stone artefact technology coupled with palaeoecological reconstruction from oxygen isotope analyses of freshwater shells from two rockshelter in the highlands of Northwest Thailand are described. Previously undocumented scales of technological variation are observed in response to environmental variation across the prehistoric landscape and through time. Three models of human behavioural ecology are used to test predictions about how foragers adapted their stone artefact technology to variation in climatic conditions and proximity to stone resources. These models are found to be problematic and are modified by including multiple optima that reflect the specific ecological conditions under consideration.     

清代纪年惠安石雕龙柱

惠安石雕为世人所称道,但因散存于各地,一时难窥其全貌,故以现存的清代纪年惠安石雕龙柱略述清代惠安派石雕龙柱的概貌。     

A geometric morphometric relationship predicts stone flake shape and size variability

The archaeological record represents a window onto the complex relationship between stone artefact variance and hominin behaviour. Differences in the shapes and sizes of stone flakes—the most abundant remains of past behaviours for much of human evolutionary history—may be underpinned by variation in a range of different environmental and behavioural factors. Controlled flake production experiments have drawn inferences between flake platform preparation behaviours, which have thus far been approximated by linear measurements, and different aspects of overall stone flake variability (Dibble and Rezek J Archaeol Sci 36:1945–1954, 2009; Lin et al. Am Antiq 724–745, 2013; Magnani et al. J Archaeol Sci 46:37–49, 2014; Rezek et al. J Archaeol Sci 38:1346–1359, 2011). However, when the results are applied to archaeological assemblages, there remains a substantial amount of unexplained variability. It is unclear whether this disparity between explanatory models and archaeological data is a result of measurement error on certain key variables, whether traditional analyses are somehow a general limiting factor, or whether there are additional flake shape and size drivers that remain unaccounted for. To try and circumvent these issues, here, we describe a shape analysis approach to assessing stone flake variability including a newly developed three-dimensional geometric morphometric method (‘3DGM’). We use 3DGM to demonstrate that a relationship between platform and flake body governs flake shape and size variability. Contingently, we show that by using this 3DGM approach, we can use flake platform attributes to both (1) make fairly accurate stone flake size predictions and (2) make relatively detailed predictions of stone flake shape. Whether conscious or instinctive, an understanding of this geometric relationship would have been critical to past knappers effectively controlling the production of desired stone flakes. However, despite being able to holistically and accurately incorporate three-dimensional flake variance into our analyses, the behavioural drivers of this variance remain elusive.     

清代学者利用金石资料研究唐代地理的成就及意义

清代是金石学研究的黄金时期,有关金石的著述层出不穷,研究成果亦蔚为可观。因唐代石刻在历代碑石中所占比重较大,故清代学者的金石研究成果中有关唐代历史的内容最为繁富,而墓志碑石的特殊性又决定了其中蕴含着大量地理方面的内容,因此清代金石研究中有关唐代地理的部分颇有价值。本文即从折冲府府名考逸、郡县之沿革隶属及地名讹误、佛教寺院、《长安志》考补等四个方面论述清代学者的研究成就,探讨这些成果的价值及其对今后唐史研究的借鉴意义。     

Biometric variables predict stone tool functional performance more effectively than tool‐form attributes: a case study in handaxe loading capabilities

Both the form of a stone tool and the anatomy of the individual using it have potential to influence its cutting performance. To date, however, the selective pressures acting on stone‐tool form and hominin biometric/biomechanical attributes have been investigated in isolation and their relative influence on performance have never been compared directly. This paper examines the influence of both tool‐form attributes and biometric variation on the functional performance of Acheulean handaxes. Specifically, it investigates the impact of 13 tool attributes and eight biometric traits on the working forces applied through the edge of 457 replica tools. The relative contribution of tool‐form and biometric attributes to handaxe loading levels were examined statistically. Results identify that both tool‐form attributes and biometric traits are significantly related to loading; however, tool–user biometric variation has a substantially greater impact relative to tool‐form attributes. This difference was demonstrated by up to a factor of 10. These results bear directly on the co‐evolutionary relationships of stone tools and hominin anatomy, and the comparative strength of selective pressure acting on each. They also underline why handaxe forms may have been free to vary in form across time and space without necessarily incurring critical impacts on their functional capabilities.     

Weathering of Calcarenite Monuments at Roman and Byzantine Archaeological Sites at Sabratha,Northwestern Libya: A Pilot Study

The Roman and Byzantine monuments at Sabratha in northwest Libya represent cultural heritage of remarkable global significance. This report describes the weathering damage of calcarenites, the most dominant stone type used in the construction of monuments in the ancient city of Sabratha. Stone loss, particularly alveolar weathering, notching and breakout of compact stone fragments, dominates deterioration phenomena. Other weathering forms include stone detachment (granular disintegration into sand) and fractures. Most of the studied monuments are also severely affected by biodeterioration, due to microorganism colonization that appears as biofilm. Both the low durability of the calcarenites and the marine environment with characteristic humidity and salt-rich marine spray are the important factors contributing to stone weathering. The results obtained in this pilot study may be used as a guideline for future restoration works.