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A systematic approach to the study of durability of wall surface treatments has been set up by the authors since some years. The study, previously based on accelerated aging tests and subsequent measurement of surface deterioration of treated and untreated specimens, has now been extended to full-scale facades. Three small constructions designed by the authors with modular facades made of sandstone and/or soft-mud facing bricks have been built in open field. A continuous content of water in the subsoil can be provided so that the capillary rise of water into the masonry is assured; soluble salts can also be provided from the soil. Some of the facades have been treated with protective materials, some others will be treated after deterioration. Besides collection of data concerning the environment and the moisture and salt movements in the walls, the deterioration of the external surfaces, the influence of mortar joints on moisture distribution and of the position and exposure of the material on the deterioration are being taken into account. Comparison between the in-situ and laboratory results are being carried out in order to adjust the aging tests to the natural environment.

A methodology of investigation and diagnosis on the built patrimony of historic centres in seismic areas is presented with the aim of collecting an extensive knowledge on the structural typologies and behaviour of historic masonry buildings. This investigation is also the base for the prevention and/or repair of damages caused by earthquakes. Small historic centres or residential buildings in larger centres have been considered for long time as “minor architecture”, but they are meaningful testimonies of the local cultural heritage and express the evolution of a society and of its cultural identity. The results of the investigation carried out on different Italian historic centers, allowed also a critical review of the reliability of the analytical models and of the effectiveness of the repair techniques applied in the past decades. The guidelines emerging from the research results are here presented. A “minimal” diagnostic investigation program is also suggested, in order to support the designers in their projects and to set up appropriate mathematical models to study the vulnerability of the structures.

[EN] After the collapse of some heavy buildings and towers in Italy and elsewhere, the hypothesis of possible continuous damage to these structures due to the dead and cyclic loads (wind, temperature variations, etc.) has been formulated by the authors. The long term behaviour of historic masonry has also been detected by laboratory creep and cyclic tests. The results indicate that a laboratory and on site investigation together with analytical modelling are important peculiarly for tall bell-towers. The application of these procedures on the Bell-Tower of the Cathedral of Monza is here reported and discussed., [ES] Tras el colapso de varios edificios de fábrica y torres en algunos países como Italia, los autores han formulado la hipótesis de un posible deterioro continuo de dichas estructuras debido tanto a las solicitaciones derivadas del peso propio como de las cargas cíclicas (viento, variaciones de temperatura, etc). El comportamiento a largo plazo de la mampostería histórica ha sido también objeto de estudio mediante un seguimiento continuo de ensayos en laboratorio y la aplicación de pruebas cíclicas. Los resultados indican que una investigación, tanto en laboratorio e in situ, sumada a una modelización analítica puede resultar fundamental en casos de campanarios de cierta altura. A continuación, se propone la aplicación de dichos procedimientos en el Campanario de la Catedral de Monza., La investigación ha sido apoyada por el CNR-GNDT, MURST y la parroquia de Monza. Los autores desean agradecer a los Srs. P. Perolari, G. Ghilardi, M. Cucchi, M. Antico, C. Arcadi y M. Iscandri por su ayuda y colaboración en el trabajo experimental tanto in situ como en laboratorio.

The research is part of a larger project, within an international cooperation, supported by UNESCO, for the study, restoration, and revitalization of Byzantine and Ottoman monuments in Southern Albania. The project was carried out on the Saint Nicholas monastic complex located in the Mesopotam area (Albania) by a multidisciplinary group of researchers from different Italian universities. Using integrated surveying technologies, the diagnostic investigation focused on enhancing our knowledge of structural behavior as a qualifying element for future conservation and maintenance programs. The aim was to develop interpretive models able to connect thematic and geometric information to the history of the monument by reading and recognizing the constructive technologies that were employed. Hence, the term “surveying techniques” includes geometrical surveys by laser scanner and photogrammetry, stratigraphic analysis, crack pattern surveys, and crack monitoring. The study was carried out on the Church of Saint Ni...

The earthquake occurred on the 6th of April 2009 in the Abruzzo Region of Italy, seriously hit the Cultural Heritage (C.H.) patrimony with major destructive effects on L’Aquila, a city of 70,000 inhabitants with the size and the historical and strategic importance of the Region capital. The emergency activities to protect the C.H. have been developed on two parallel levels: (1) survey and assessment of damages, (2) implementation of temporary safety measures. The organization of the emergency actions was managed by a centralized structure, the so called Function 15 “Protection of Cultural Heritage”, that coordinated the surveys of protected buildings and the design and implementation of temporary safety measures. This allowed the cooperation among different involved subjects (Ministry of Cultural Heritage officers, experts on structural engineering, architects and historians from Universities and private offices and fire brigade teams). The first level of the operating process was carried out on site by expert teams filling up dedicated survey forms for churches and palaces, developed by the Civil Protection Group GLABEC (a Working group for Cultural Heritage); the forms were based on the standardization of damage survey allowing for its immediate interpretation. The second level was based on the past experience in the field of temporary safety measures; the idea was to provide a technical and scientific support in order to assist the work of fire brigade, highly experienced professionals in the “emergency” field. After the first emergency phase the damages of the most important buildings were more carefully investigated and the possible damage progression constantly monitored. The paper presents the case of the Spanish Fortress in L’Aquila, severely damaged by the earthquake; the description concerns the definition of the damages and the interpretation of the activated collapse mechanisms. Finally the design of the provisional strengthening interventions and the on site diagnostic investigations are presented.

Historic masonries of the cultural heritage are aged and heterogeneous systems which are subjected to long-term exposition to the external environment. In such conditions, they can easily come in to contact with a consistent range of damaging agents, including water and salts sources. The related salt-induced damage is widely considered as one of the most dangerous decay process for their preservation. Conservative operations become therefore necessary and are performed with new materials that must fulfil specific requirements regarding their compatibility with the original ones and their resistance to damaging agents, especially in term of salt-resistance. The use of ready-mixed mortars in the restoration field has become a common practice and the number of commercial products currently available in the market is increasing. The present work reports the investigation on four types of ready-mixed mortars based on NHL binders and on two commercial NHL binders, together with the preliminary laboratory tests to assess the durability of mortar specimens to salt decay. The investigation provided useful information on the relationship between compositional and microstructural features and damage.

Creep and the creep-fatigue interaction have shown to strongly influence the mechanical behaviour of ancient masonry and long-term heavy loads proved to cause a continuous damage. The problem of achieving a reliable life-time estimate of historic masonry toward the effects of persistent loading has been dealt with by a probabilistic approach. The results of pseudo-creep tests on ancient masonry of different ages and their interpretation through a probabilistic model are presented, aimed to the individuation of a random variable as a significant index of vulnerability, and to the solution of the classic problem of reliability in stochastic conditions.

This paper presents and discusses the results of investigations carried out by the authors on two castles that are considered as case histories within a project financed by the European Commission (project EVK4-2001-00091 ONSITEFORMASONRY), coordinated by C. Maierhofer of Bundesanstalt für Materialforschung und prüfung (BAM), Germany. An extensive investigation programme (including sonic, radar, flat-jack, coring, boroscopy, etc.) was planned to support the preservation and restoration actions of two ancient castles. The experience from this investigation shows the importance of the diagnosis project in selecting the most relevant strategies and tests for each specific problem.

A nonlinear finite element model was developed to simulate the nonlinear response of three-leaf masonry specimens, which were subjected to laboratory tests with the aim of investigating the mechanical behaviour of multiple-leaf stone masonry walls up to failure. The specimens consisted of two external leaves made of stone bricks and mortar joints, and an internal leaf in mortar and stone aggregate. Different loading conditions, typologies of the collar joints, and stone types were taken into account. The constitutive law implemented in the model is characterized by a damage tensor, which allows the damage-induced anisotropy accompanying the cracking process to be described. To follow the post-peak behaviour of the specimens with sufficient accuracy it was necessary to make the damage model non-local, to avoid mesh-dependency effects related to the strain-softening behaviour of the material. Comparisons between the predicted and measured failure loads are quite satisfactory in most of the studied cases.

A research has started aiming at evaluating the influence of aggressive environmental conditions on the bond between various composites and masonry substrates already decayed. A series of on-site experimental tests was carried out on full-scale masonry models, built in open air in a polluted area and artificially exposed since years to capillary rise of a solution of water and salt, so to create salt crystallization cycles. Composite materials are widely used in civil engineering for strengthening purposes, especially in seismic areas, where several existing buildings need structural retrofitting. Nevertheless, some conditions may cause damaging on their applications: moisture, thermal effects, creep, fatigue, ultraviolet radiation, and fire. The possible influence of moisture presence and salt crystallization cycles on the various composites was investigated by means of pull-off tests, whose first results are herein presented. The investigation aims at finding the better compromise between good strength reinforcement and minor damage on the historical masonry substrates, in case of reinforcement failure.

The long-term research experience of the authors has highlighted the importance of gaining knowledge of the building through experimental investigation. Recently the authors intensively studied the Syracuse Cathedral (Sicily, Italy) to evaluate the structural state of the preservation of the pillars. The Cathedral of Syracuse was built in different phases on an ancient Greek temple from the fifth century bc and modified throughout later centuries. The pillars of the central nave, obtained by cutting the temple cell walls, show a complex situation of damage and repairs. An investigation program (including radar, sonic, and ultrasonic tests, for example) has been recently planned, aimed to design the preservation and restoration actions. An accurate geometric survey of the surface problems and defects allowed the localization of the most damaged area, suggesting the need for further control by non-destructive testing (NDT). The results obtained from this survey were compared with the results of the other ty...

Aim of this research was to evaluate the possible application of the AE technique to study the response of multiple leaf masonry repaired with different techniques. The results of shear tests carried out on three specimens repaired after failure are presented on an explorative basis; on two of them the acoustic emission (AE) technique was also used. Through a number of sensors and by triangulation, this technique makes it possible to identify the location of the damage, unknown initially, and subsequently to assess the stability of its evolution. Using the AE technique the area of the material where the cracks propagated during shear tests was identified. These analyses made it possible to evaluate the effectiveness of repair interventions through parameters other than stress and strain, and contributed to the identification of the most suitable methodology for their optimisation.

The paper analyses the most recent research carried out in Italy concerning the seismic behaviour of historic buildings. The last Umbria (Italy) earthquake in 1997 was an interesting on site test for the evaluation of the repair and prevention techniques applied to masonry building of historic centres in seismic areas, but also of the structural modelling. Most of the situations examined made important contributions to a general re-thinking of masonry evaluation and strengthening. The great importance in the mechanical behaviour of a building of building rules and of structural details, as well as transformation phases has been demonstrated.

The scope of Rilem Committee TC167-COM is the characterisation of old mortars, with respect to their repair. For damage analysis of historic buildings, the characterisation of the old mortars may represent an essential part of the investigations. This statement can also be inverted, keeping in mind the scope of the committee and more specifically the second part ‘with respect to their repair’. It is essential to have knowledge of the condition of the old mortar and of the causes of any decay that has occurred (VAN HEES et al., 2000). The aim of this article is to underline the importance of knowledge on the factors that influence the way in which degradation of materials- and especially mortars in monuments - occurs. The most common forms of degradation of mortar in monuments, as well as the type of investigation, which is necessary to understand the cause of the damage, are described. On the basis of the assessed decay form and decay process, the most adequate repair method and the most suitable repair mortar can be chosen. The diagnosis of the damage is very often forgotten in practice, even though this is a fundamental step to guarantee a compatible and durable restoration. Such negligence can lead to major incompatibility problems in the case of repair mortar application. The approach discussed in this document can result in a better understanding of the causes of incompatibility and in guidelines for compatible repair mortars, based on the specific conditions of the individual monument. This article describes the approach, as proposed by Rilem TC167-COM .

The Cathedral of Noto was damaged after the earthquake that hit Sicily in 1990. Soon after the event, cracks appeared on the domes of the lateral naves, and also on the pillars. In 1992 some provisional work had been carried out in view of confining the pillars of the central nave that were damaged. Some pictures made after the earthquake also show clearly the presence of moisture rise on the pillars and walls. A sudden collapse due to the damages was probably not expected, so that no other measures were taken to better strengthen and repair the structures. Only after the collapse of the Civic Tower in Pavia (1989) and the following research (Masonry Int J 6 (1992) 11, Second International Conference RILEM on Rehabilitation of Structures, Highett, Australia (1998) 542), it was clearly shown that in case of high stresses on low-strength masonry an existing damage can slowly lead to partial or total collapse of the structure over a long time. It seems a confirmation of this long-term behaviour of the structures that the Cathedral collapse took place in 1996, 6 years after the earthquake, which had certainly caused high damages to the structure.

Following the experimental and structural investigation the design for reconstruction was proposed. The authors were requested to test new materials, stones, mortars, grouts for injection in order to choose and proposed the material to be used for the reconstruction of the pillar and for the repair of damaged elements.

After an earthquake, which struck the Eastern part of Sicily in 1990, some structural elements of the Church of S. Nicolo l'Arena in Catania, as the dome and the vaults, were damaged; vertical cracks on the two pillars were detected. It is not clear whether those cracks were already visible and were simply propagating during the earthquake. It is known that the two pillars probably belong to the original construction of the church. An investigation programme (including historical research and experimental investigation with sonic, radar, flat-jack, coring, boroscopy, etc.) has been recently planned to design the preservation and restoration actions. The results obtained from sonic tests were compared to the results of the other type of tests in order to set up an investigation procedure useful for these cases. The paper presents and discusses the preliminary results of the research carried out by the authors.

Historic buildings rarely show themselves as they were to their origins, with the same shape and materials The signs of local repairs, but also modifications and expansions are reported on the building as indelible scars that need to be recognized and interpreted. It is important to read these signs, especially in load-bearing structures. One of the first steps for this study is the correct analysis and classification of the quality of the load-bearing masonry, with the help of both an accurate visual inspection and a diagnostic investigation. The classification of the correct masonry typology is now requested also by the last Italian seismic code (NTC 14.01.2008 and annexes), that supplies different mechanical parameters useful for the structural evaluation, according to the masonry typology. Serious mistakes can be made in the structural evaluation of a historic stone masonry if the definition of the masonry typology is incorrect. In several cases there is no coincidence between the visible masonry texture and the transversal cross section. There are different levels of approaching this matter, starting from a description based on a visual inspection, that can be carried out with the help of a template, till the parameters definition achieved by in situ investigation tests. Several parameters may be important to be determined in order to evaluate properly a masonry. The results of the experimental investigation (with a comparison between NDT and MDT tests) and a methodology for the analysis of the masonry quality, according to the standard suggestions for the knowledge levels, reporting all the pros and cons of all methods, are here presented.

A presentation is given of the fundamental design choices and of the selection of the most appropriate materials and techniques which have been made for strengthening the Monza cathedral bell-tower, based on investigation and structural assessment carried out prior to and during the design process. The results of the experimental and numerical investigation will first be given in order to explain the reasons for the design choice.

Sonic tests and other diagnostic techniques were systematically carried out on the existing walls of the Cathedral of Noto. The right aisle and most of the dome of the Cathedral collapsed in 1996. The aim of the research was to verify the state of damage and/or conservation of the walls and piers in view of the reconstruction of the damaged part of the Cathedral. Sonic tests were used to control the effect of grout injection used as a possible technique of repair of the damaged masonry. The results show that sonic tests can be successfully applied for the diagnosis and the effectiveness control of repair techniques.

The principles of ESPI (electronic speckle pattern interferometry) are summarised and the use of optical interferometric methods is discussed in comparison with common measuring techniques for measuring the deformation parameters of solid masonry units under mechanical tests. The brick–mortar interaction under certain states of stress has also been studied, owing to the influence of mortar strength and deformability on the brick masonry behaviour under compression and shear. The difficulties related to the use of classical measurement devices, such as strain gauges or displacement transducers on masonry, are highlighted. The experimental results obtained show the effectiveness of the ESPI technique in the case of low-stiffness materials and small specimens. The quantitative evaluation by ESPI measurements of the deformability characteristics of solid softmud bricks is also proposed.

In the last 30 years, the restoration of our cultural heritage has become common practice. Initially, only very important monumental buildings were saved and restored, while the rest were demolished and replaced. Then historic centres and groups of buildings were protected, preserving all structures in a reaction to the previous systematic spoiling of the cultural heritage. Subsequently, it was recognized that all urban structures, including small dwellings, should be respected and preserved with great care. Nowadays, this respect for old buildings means finding out every detail of their architecture, fabric and structure. The importance of controlling the efficacy of the techniques of repair and improvement is appreciated[1]. This article attempts to provide a state-of-the-art review of the European, and in particular the Italian, attitude towards the reuse of historic buildings with the help of some case histories.

A research, made in collaboration with Politecnico di Milano and University of Padua, has started with the aim of evaluating the influence of aggressive environmental conditions (moisture, temperature and soluble salts presence) on the bond between FRP/TRM and masonry substrates. Experimental tests were carried out on site on full-scale masonry models, built in open air in a polluted area in the hinterland of Milan, naturally subjected to thermal, R.H. and UV cycles; furthermore, they were artificially subjected to capillary rise of a solution of water and Sodium Sulphate so as to create salt crystallization cycles. On two different masonry substrates, representing a simple historic masonry structure, made either by soft-mud bricks or sandstone units with lime mortar, various FRP and TRM strips were vertically applied in order to evaluate the bond at three heights. TRM were applied with two different premixed inorganic matrices (pozzolanic lime based mortar and cement polymer modified mortar) and FRP with an organic matrix (epoxy resin). The fibres used were unidirectional carbon and glass fabrics for FRP, and a bidirectional carbon net for TRM. The bond was evaluated by means of pull-off tests and the first results, herein presented, show the influence of moisture presence and of salt crystallization cycles on the different used matrices.

An experimental research on of masonry has been carried out. Thermal cycles and salt crystallization test were carried out on solid brick samples and small masonry assemblages, using bricks and mortars produced in Italy and in Poland. The specimens were strengthened with CFRP textiles or laminates in different configurations. To perform thermal accelerated ageing tests, specimens were subjected to a temperature variation ranging between −10 and +70 °C, applied cyclically. The procedure was validated during testing. The results showed the influence of the properties of the adhesive and of the strength of the brick in the failure of specimens. As for salt decay tests, a RILEM pre-standard procedure was followed to evaluate the resistance of tested materials to sulfates. Damage evolution was monitored by visual observation and by quantification, at each 4-week cycle, of material loss by a laser profilometer. The results showed the rising of salt from the uncovered surface as from the first week of observation, and also a concentration of stresses underneath the fibres. The pull-off test was chosen as reference test, in order to the loss of bond. The durability was also checked on reference unreinforced specimens. Pull off tests were carried out on the surviving specimens at the end of the tests. The results among the various series of specimens are compared. This costly repair technique can show adhesion problems due to humidity and high temperature.

A joint U.S./Italian effort is investigating the effectiveness of grout injection for repair of damaged or deteriorated masonry structures. A nondestructive acoustic tomographic imaging technique has been used throughout the program to determine the effectiveness of the repair processes. Pulse velocity information is used for input into a computer program which develops a three-dimensional image of the velocity distribution through the section. Recent work to characterize input waveforms, investigate the effect of mortar joints on measured pulse travel times, and smoothing of analytical data has improved the accuracy of velocity reconstructions.

An increasing interest in the pozzolanic activity of bricks with calcium hydrate has been shown recently by researchers dealing with the production of new hydraulic materials for the masonry industry. Furthermore, deteriorated mortars of historic buildings and damaged masonries require repointing, repair or strengthening with mortars and grouts compatible with the existing materials. Admixtures of hydrated lime and crushed bricks also have an acceptable colour from an aesthetic point of view. This paper concerns a systematic research on the pozzolanicity of different bricks and clays. The laboratory tests were based on chemical, mineralogical-petrographical analyses and pozzolanicity tests, applied to measure the capacity of crushed bricks in fixing calcium hydrate (pozzolanicity). Various types of clay, calcinated at different temperatures, are subjected to the pozzolanicity test in order to state the degree of pozzolanicity. The research intends to give guidelines for the production and use of pozzolanic bricks and clays for the preparation of hydraulic mortars and grouts.

During their life Cultural Heritage buildings suffer different attacks due to the changes induced to the surrounding environment along the years. Each attack causes damages of different magnitude which are, often, time dependent. Salt crystallization is one of the highest causes of damage in masonry connected with an aggressive environment. Mortar joints as brick and stone can be a vehicle of the water and salts coming from capillary rise or sea spray. The maintenance against damages consists in replacing (re-pointing) the joint using a new mortar. The commercial mortars for repair, present nowadays on the market, give rise to a question: how durable is the mortar once it has been used to repair masonry? In the chapter, to investigate durability of these materials, and the eventual damage that they induce at the interface mortar/brick, a procedure based on salt crystallization tests is described and the development of a simple probabilistic damage model introduced. The salt crystallization tests were carried out on brick masonry specimens prepared with the same type of bricks and six types of commercial mortars based on natural hydraulic binders (NHL). During the test the loss of material from the surface was measured and assumed as parameter of damage. The loss is referred to the vertical section of the specimen and quantified through a computer code starting from successive readings of the surface decay along defined profiles using a laser profilometer device. The randomness affecting the damage due to the salt crystallization and the consequent continuing loss of material suggests studying the deterioration under a probabilistic point of view where the continuous deterioration of specimens can be assumed to be a stochastic process.

After the earthquake that stroke the city of L’Aquila during the night of April 6th 2009, many historical buildings at the city centre were severly damaged. Nevertheless many others survived the seismic event with only local damages, showing a good mechanical behaviour against vertical and horizontal actions. In order to continue preserving these buildings, a careful investigation is necessary before applying any repair technique, new or traditional to understand the past design practices for building durable and safe structures. In order to understand the structural behaviour of the church of St. Biagio in L’aquila, an extensive diagnostic investigation based on non-destructive and minor destructive techniques was carried out by the authors. The paper describes mainly the applied methodology which can produce some guidelines to be followed in the future study of other Cultural Heritage (C. H.) buildings hit by the earthquake.

The authors applied sonic tests to study the propagation of sonic waves through stone masonry walls. In particular, tests were made to study the effect of the joints and the influence of the characteristics of the stones surface, rough or smooth, on the measurement of the sonic velocities on granite masonry specimens. A series of direct, indirect, and impact echo sonic tests were performed on single stones and on columns of stones with dry and mortar joints to obtain P- and R-wave velocities. The results allowed a better understanding of the influence of the stones characteristics and the samples geometries, namely the number of joints, to the global response of the masonry to the propagation of sonic waves. This study also allowed verifying the complementarity of the different sonic test configurations and the interest to cross information from more than one technique to obtain more reliable information. Finally, significant results were also achieved concerning the relationship between the param...

Electronic speckle pattern interferometry (ESPI) can be a powerful tool for efficient non-destructive testing and evaluation of micro-deformations of masonry materials and structures. Unlike traditional transducers, ESPI requires no direct contact with the object, and the full-field visualisation it offers provides for a better understanding of the surface behaviour. This paper describes an in-plane deformation inspection system which has been built up for an automatic acquisition of interferograms at different stages of a test. The system is applied to the evaluation of some mechanical characteristics of masonry components. Qualitative and quantitative results are obtained and an overall discussion is presented.

Since 2001 the authors have been involved with the archaeologists of the Fondazioni Lerici, Politecnico di Milano, in the preservation of some Hindu temples in Mỹ Sơn, Vietnam. The characterisation of the brick- masonry materials was carried out at the Politecnico di Milano. Especially interesting was the successful study of the natural resin used to bond externally the bricks in the masonry; this allowed the formulation of a new compatible resin to be used for the conservation project. In the masonry internal leaf, the joint material, based on clay, was substituted by a new hydrated lime and powdered bricks mortar. The results of the research presented here allowed the direct application of the new materials in the conservation project of G1, G3, and G5 of group G.

The movement of moisture in masonry walls can be particularly problematical, especially in the region of the foundations. Capillary rise can give rise to significant durability problems for the masonry in the structure. In cold climates the action of freeze/thaw cycles in conjunction with capillary rise can result in significant damage. A novel technique of identifying moisture movement in masonry walls using impulse radar is described. Studies have been undertaken on full-scale experimental structures in Milan, Italy. This work illustrates the applicability of digital impulse radar to identifying the zones of fully saturated capillary rise, partially saturated capillary rise and the ‘dry zone’.

The Friuli and Irpinia earthquakes, and subsequent experiences, have underscored the need for adequate damage assessment prior to seismic rehabilitation. Furthermore, assessment can be enhanced by preventive studies under the guidance of those in charge of hazard mitigation (architects, engineers, etc.). Research procedures must be defined so that findings can be used for damage assessment and as input data for structural analysis and control models. This paper provides evaluations of in-situ and laboratory tests on materials for existing unreinforced masonry structures and, in particular, touches upon the difficulty of interpreting the results of NDE tests. Furthermore the need for a design of the investigation prepared by persons responsible for the rehabilitation is pointed out.

An accurate diagnosis of the state of conservation of historic structures is based on an extensive experimental investigation and on an appropriate structural analysis. A methodology of investigation to be applied to Cultural Heritage (C.H.) buildings is presented by the authors, based on a long experience in the field. The investigation steps are described, from the collection of historical documents and the visual inspection to: the geometrical and crack pattern survey, the detailed masonry section and quality description through on site mechanical and physical tests and use of Non Destructive (ND) techniques to the material characterisation and the structural monitoring.

In order to study the building technology of an old 19th century timber vault in the Palace of the Academy of Sciences in Torino, authors performed several diagnostic tests to detect the construction technique and the damages to this structure. The vault has the peculiarity of being a timber structure, made with a specific technology that is not easily visible from intrados and extrados. For this reason the interpretation of its mechanical behaviour must be based on the knowledge of its construction technology. The non destructive technique that provided the most interesting information was IR thermography. This technique provided valuable data about the timbering used to build the shell of the vault and enabled correct execution of other minor destructive tests, such as light sampling and stratigraphic investigation on the painted plaster.

Image-based modelling for cultural heritage documentation is an issue in which photogrammetry plays a fundamental role. Nowadays several commercial software packages (also at low-cost) allow the creation of accurate models by using digital images. However, a solution which automatically creates an accurate digital model from images is not available on the market yet, thus a relevant part of the work is carried out by interactive measurements. In the paper, the full reconstruction pipeline of a temple of the archaeological site of MySon (Vietnam) by using the well-known photogrammetric software PhotoModeler (EOS System Inc., Canada) is illustrated and analysed. In order to speed up the process, an innovative photogrammetric tool that is capable to interact with PhotoModeler's environment is presented. This allows the orientation of the image block in an automatic way without using any target. Then, a point cloud is extracted from the images by using manual measurements of corresponding points to plot vector features or by multi-image matching techniques, in order to automatically provide a reconstruction of the surface of the object. The accuracy of the obtained point cloud is similar to that achievable with range-based sensors. Finally, the point cloud can be interpolated in order to obtain a 3-D surface model. To verify the potential of this method, it was applied to the conservation design of the ‘G1′ temple in MySon, Vietnam. For this real case, which was listed as a UNESCO World Cultural Heritage site, the results of the automatic method for image orientation were compared with those obtainable with manual measurement, and demonstrated a similar accuracy despite a shorter elaboration time. In addition, the application of the photogrammetric 3-D model for planning future restoration activities is reported and discussed.

After an investigation on the most recent floods occurred in Italy that damaged the Cultural Heritage masonry buildings, an experimental research started on-site on full-scale masonry models exposed to the environmental agents in Milan. The masonry materials used for the full-scale models were largely investigated in the past and the models were subjected to decay caused by the capillary rise and by the crystallization of sodium sulfate coming from the foundations. These walls can actually simulate the state of naturally contaminated walls before a flood and represent a construction where the main parameters are known. A flood has been simulated by adding water for several days to the walls of the full-scale models previously contaminated by salts, then the walls were left to naturally dry. The objective is to check the effectiveness of nondestructive (ND) techniques in detecting the presence of water and the drying process and also the influence of surface treatments presence. Radar tests, thermography tests, sonic tests, as well as the minor destructive powder drilling tests were applied successfully to evaluate the moisture distribution in the masonry after flooding and during natural drying.

The earthquake that hit the city of L’Aquila, in central Italy, on the 6th of April 2009 has severely damaged most of the heritage buildings of the area. Soon after the event, a first survey of damage to ancient churches and palaces has been carried out according to a predefined classification procedure. Subsequently, a more detailed damage analysis was started in order to facilitate decision on future interventions. For one of these churches, S. Biagio Amiterno, damage consisted in the collapse of the upper part of the façade, in the localized collapse of the main vault, and in an extended crack pattern in vaults, columns, and walls. This damage pattern is interpreted here as case study. In more general terms, the exam of specific case studies gives the possibility of shedding light on various issues related to the seismic behavior of the building typologies concerned.

In conservation practice, operations aiming to restore structural functionality of historical buildings are of primary relevance. Partial rebuilding, the substitution of damaged bricks or blocks and the integration of deteriorated joints are, among others, interventions that require the introduction of new materials in a heterogeneous and aged masonry system. An appropriate durability of these interventions can only be assured if a deep knowledge of the original materials and of their state of conservation is combined with reliable understanding of the behaviour of new materials introduced. The present paper reports the results of the investigation of four commercial ready-mixed mortars based on NHL binders. The mineralogical composition of each product has been evaluated by XRD and polarization-and- fluorescence microscopy (PFM). The molecular composition of the mixes has also been evaluated by FTIR spectroscopy and the morphological features have been studied by SEM observations. The mechanical behaviour has been tested as well. Although supposedly comparable products, the mortars show different compositional features, microstructures, additives and mechanical behaviour. These are essential to evaluate compatibility with historic materials, and should be stated on the technical data sheets, or be determined. © 2009 WIT Press.

This paper describes a procedure, addressed to an articulated knowledge of the material, of the morphology and of the constructive aspects of the masonry structures, of the mechanical behaviour and of the possible failure mechanisms of complex buildings in Sulmona (AQ), an important historic centre in Central Italy. It is an area of great interest, not only considering its seismic history, but also because of the characteristics of its prestigious buildings, mainly made of multiple leaf stone masonry. The understanding of the historical buildings has made use of a direct survey of the constructions (based on a geometrical survey, on a survey of the materials and of their state of damage), of indirect information deduced by documentary sources, and of data collected through in-situ non destructive or minor destructive testing and laboratory investigation for a chemical, physical and mechanical characterisation of the masonry and of its components. Record templates and forms, some of them purposely set up, have been adopted and collected into a database for the damage and masonry quality assessment and the evaluation of the future vulnerability of the buildings to in-plane and out-of-plane actions according to damage abacuses previously produced.

The time-dependent behaviour of ancient masonry structures, often characterized by non-homogeneous load-bearing sections, is considered among the factors affecting the structural safety of monumental buildings. Together with other synergetic aspects, this has proved to be involved in collapses, which occurred during the last thirty years. Exploiting the ancient (from the Middle Ages to the sixteenth century) masonry coming from the ruins of the collapsed tower of Pavia, several experimental procedures have been adopted to understand the phenomenon, from creep to pseudo-creep tests at different time intervals, and various rheological models have been applied to describe the creep evolution and creep-induced damage, as explained later in this book in Chapter 7. Purpose of the testing activity has been initially the identifi cation of the creep behaviour as a possible cause of the collapse of buildings, then the study of factors affecting creep (rate of loading, stress level, etc.) and the set-up of the most suitable testing procedures to understand the phenomenon, and fi nally the individuation of signifi cant parameters (e.g. strain rate of secondary creep phase) that may be referred to as risk indicators in real structures. After the fi rst tests carried out on prisms of dimension 400 × 600 × 700 mm described in Chapter 1, long-term tests on six prisms coming from the ruins of the tower of Pavia and one from the crypt of Monza were performed, some of which lasted 1000 days. Considering that long-term tests require constant

Masonry presents some inadequacies due to its almost total lack of tensile strength. Typical damage to multiple leaf walls during earthquakes is the loss of bond between the leaves with consequent collapse of the external leaf. Retrofitting or repair of this damage is a very difficult task. In many cases grout injection or wall jacketing fail due to incompatibility with the construction technique of the walls.\ud \ud A complementary technique to the grouting has been proposed by the authors. Experimental results and applications of the technique on site have shown positive characteristics and the results of tests carried out on site show, in some cases, increases in shear strength and stiffness of the masonry walls.

After the earthquake that hit central Italy in 1979, many small historic centers were restored. A subsequent seismic event occurred in 1997 in Umbria‐Marche regions revealed that some techniques used in the previous interventions were not successful due to low durability of new materials and/or incompatibility between the new and the existing materials and structures. An extensive investigation on four small typical historic centers in Umbria was carried out. The objectives of the research were: (i) to define a methodology for the vulnerability analysis of historic buildings at the level of the historic centre, (ii) to collect information on the effectiveness of the repair techniques both traditional and new, (iii) to set up Databases storing the information useful to prepare rescue plans, (iv) to use the collected knowledge for the implementation of reliable models for the vulnerability analysis, (v) to prepare guidelines for investigation and vulnerability analysis.

Strategies and methodologies for the assessment of historic masonry structures based on non-destructive and minor-destructive testing methods were developed in the European Research Project ONSITEFORMASONRY and were successfully applied to assess the structure and material properties of selected structural elements in the Altes Museum in Berlin-Mitte. For the planning of a broad reconstruction within the framework of a master plan concerning the whole of Museum Island in Berlin, several questions arose which are also typical for other historic structures in general, thus the Altes Museum was chosen as a pilot site for the validation of non-destructive testing methods.

In view of preserving the historical heritage, the deterioration processes of masonry materials and the long term damage of multiple leaf historic buildings is studied from an experimental and a numerical point of view. Durability tests and pseudo-creep tests have been carried out and interpreted through probabilistic models for the service life prediction. The precocious recognition of structural critical states will allow to design repair and strengthening interventions and to prevent total or partial failure of the constructions.