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The impregnation of the exterior surface of a masonry wall with a water repellent is a common intervention in (historic) building renovation and maintenance. Such treatments, whilst degrading at the surface with time under influence of ultra violet light, remain effective below the surface several decades after their application. During renovation works of masonry previously treated with a water repellent, the question arises whether it is necessary to repeat the hydrophobic treatment of the entire masonry after repointing. Opposing opinions exist with this regard, but no research clearly supporting one or the other. This research investigates for the first time the effect of hydrophobic treatment when applied on previously treated and repointed masonry walls. Small masonry walls were subjected to rain periods in the laboratory and their water uptake and drying behaviour were studied. Moreover, this laboratory research was followed by 30 months of outdoor exposition of the masonry specimens. The following cases were considered: (1) wall treated with water repellent, (2) wall treated with water repellent, followed by repointing but without new water repellent treatment, (3) wall treated with water repellent, followed by repointing and retreatment. This was done for three different types of pointing mortar: ordinary Portland cement and natural hydraulic lime with standard sand, and natural hydraulic lime with sand with one grain size. The results show that, after prolonged rain periods, the water uptake by repointed but not retreated masonry is comparable to that of untreated, non-hydrophobic masonry, whereas drying is considerably slower. This leads to a high saturation degree in repointed but not retreated masonry, which, in turn, increases the risk of damage to the masonry by e.g. frost. Therefore, retreating repointed hydrophobic masonry should definitively be considered., Heritage & Architecture

Salt weathering is one of the most recurrent damage processes affecting both the natural and the built environment. Due to the complexity of the process, numerical models are rarely applied in practice; accelerated weathering tests in laboratory are still the most common way to assess and forecast durability of (conservation and renovation) building materials....., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Heritage & Architecture

Sodium chloride (NaCl) is one of the most commonly occurring weathering agents, responsible for a progressive damage in mortar. Current solutions to mitigate salt damage in mortar, such as the use of mixed-in water repellent additives, have often exhibited low compatibility with the existing building fabric. In the last years, research has shown promising results in mitigating salt decay by making use of crystallisation inhibitors. Sodium ferrocyanide is one of the inhibitors that has proven to be particularly effective to reduce damage due to sodium chloride crystallisation. In this research the possibility of developing hydraulic mortars with mixed-in inhibitor (sodium ferrocyanide) for an improved resistance to sodium chloride crystallisation damage is investigated. As a first step, the interaction between the inhibitor and the hydraulic binder: natural hydraulic lime (NHL), was studied; the results are presented in this paper. Various concentrations of sodium ferrocyanide were tested (0%, 0.1% and 1% by binder weight). The effect of the inhibitor on several physical (hydration, water absorption, pore size distribution) and mechanical (compressive and flexural strength) properties was experimentally assessed, using several complementary methods and techniques. The results show that the addition of the sodium ferrocyanide does not affect the fresh and hardened properties of mortar. These results are promising and open new possibilities for the application of inhibitors to improve the durability of hydraulic mortars., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Heritage & Architecture, Materials and Environment

Crystallisation due to commonly occurring salts like sodium chloride (NaCl) is a known cause of damage in the built environment. Use of crystallisation inhibitors is a potential solution to reduce salt decay in building materials. Researchers have reported lower damage when sodium ferrocyanide (NaFeCN), a known NaCl crystallisation inhibitor, is mixed in fresh mortar. However, the high solubility of NaFeCN in water could make it susceptible to leaching and thus diminish its effect over time., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Heritage & Architecture, Materials and Environment

Reconstruction and recovery of historic cities after destruction due to conflict or natural disasters have gained increasing relevance in the last decades. The investigation of international examples of recovery after war or natural catastrophic events can provide knowledge for improving guidance and strategies for sustainable reconstruction/ intervention in similar cases in the future. This paper aims to identify and analyze the legal, administrative, social, and economic factors that can favor the reconstruction and recovery processes of the historic city and its residential neighborhoods. An extensive review of international examples and literature on guidance has been conducted to provide insight into best practices and potential solutions. As a result, a set of lessons learned that can be used to address post-conflict and post-disaster recovery and reconstruction in similar situations is given., Heritage & Architecture

Adaptive reuse (AR) of heritage buildings is common practice in The Netherlands and is becoming more and more common at the International level. While AR projects are generally considered positive actions towards preserving the qualities of heritage buildings, not all projects have similar (positive) impact. To propose a methodology for dealing with the AR of heritage buildings aiming for positive impact, the AR process has been studied. After a comprehensive systematic literature review, a theoretical model representing the steps of the AR process has been sketched (fig.1). This model depicts the ideal steps of architects in dealing with heritage buildings. To check whether these steps are actually followed, two effective AR projects, winners of the NRP golden phoenix prize, were studied namely ‘LocHal’ in Tilburg (fig.2) and ‘Energiehuis’ in Dordrecht (fig.3). During the research, the cases were visited, the published literature on the cases was reviewed, and architects and other stakeholders involved were interviewed. The interviews were based on the steps of the theoretical model but the model was not shown to the architects till the end of the interview. Finally feedback was asked from the architects if the model represented their actual steps and where they diverged. The analysis of the collected data confirmed that architects followed the steps reported in figure 1. However, the process was reported to be not linear, as suggested in the model, but to include several loops between some of the steps, mainly between steps 1, 2 , 3, 4, 5, and 6 (fig.4). Next to refining of the AR model, investigation of the case studies led to the identification of tools and methods used by architects, which have possibly positively influenced the effectiveness (positive impact) of the final result. Both case studies distinguished themselves, according to the NRP jury reports, because of their high ‘social value creation’. Involving end-users, other producers, and original users, The organization of this international colloquium was made possible through the generous fi nancial support of the DIOS Incentive Fund (UHasselt), the Doctoral School of Behavioral Sciences and Humanities (UHasselt), and the Research Foundation Flanders (FWO), as well as the invaluable practical assistance provided by the Faculty of Architecture and Arts of UHasselt and the Flanders Architecture Institute. Our heartfelt appreciation goes out to all our esteemed colleagues whose dedicated efforts contributed to the seamless execution of this event. This colloquium is organized as an extension of the exhibition As Found: Experiments in Preservation by the Flanders Architecture Institute. Curated by Sofi e De Caigny, Hulya Ertas and Bie Plevoets, the exhibition is on show at De Singel, Antwerp, from 6 September 2023 to 17 March 2024. The exhibition is accompanied by a catalogue, available in English (ISBN: 9789492567321) and Dutch (ISBN: 9789492567338)., Heritage & Architecture

This paper investigates the leaching behaviour of sodium ferrocyanide, a known crystallisation inhibitor of sodium chloride, which is added to mortars for mitigation of salt decay. Leaching and depletion of the inhibitor is a practical performance related issue that might over time, make the inhibitor less effective against salt decay. In this research, the inhibitor was added to natural hydraulic lime (NHL) mortars during the mixing stage. Leaching of the inhibitor from the hardened mortar was assessed experimentally in laboratory. Both diffusion- and advection-driven transport mechanisms were considered. Diffusion experiments were carried out in a tank leaching test setup. Capillary absorption and drying cycles were used as a driving force to study advection-driven transport. Quantification of the leached species was carried out using various analytical techniques, including UV-VIS spectroscopy, ICP-OES and ion chromatography. The results from the tank leaching test show a high effective diffusion coefficient of ferrocyanide ions, in the same order of magnitude as sodium chloride transport. The advection test shows accumulation of the inhibitor at the evaporative surface and depletion of the inhibitor in the inner layers with successive wet-dry cycles. Based on these results it can be inferred that the degree of inhibitor leaching is significant and needs to be minimised to prolong the positive effect of the inhibitor on mortar durability. Potential solutions to reduce inhibitor leaching are discussed., Heritage & Architecture, Materials and Environment

This recommendation is devoted to testing the resistance of natural stone and fired-clay brick units against salt crystallization. The procedure was developed by the RILEM TC 271-ASC to evaluate the durability of porous building materials against salt crystallization through a laboratory method that allows for accelerated testing without compromising the reliability of the results. The new procedure is designed to replicate salt damage caused by crystallization near the surface of materials as a result of capillary transport and evaporation. A new approach is proposed that considers the presence of two stages in the salt crystallization test. In the first, the accumulation stage, salts gradually accumulate on or near the surface of the material due to evaporation. In the second, the propagation stage, damage initiates and develops due to changes in moisture content and relative humidity that trigger salt dissolution and crystallization cycles. To achieve this, two types of salt were tested, namely sodium chloride and sodium sulphate, with each salt tested separately. A methodology for assessing the salt-induced damage is proposed, which includes visual and photographical observations and measurement of material loss. The procedure has been preliminarily validated in round robin tests.

This recommendation is devoted to testing the resistance of natural stone and fired-clay brick units against salt crystallization. The procedure was developed by the RILEM TC 271-ASC to evaluate the durability of porous building materials against salt crystallization through a laboratory method that allows for accelerated testing without compromising the reliability of the results. The new procedure is designed to replicate salt damage caused by crystallization near the surface of materials as a result of capillary transport and evaporation. A new approach is proposed that considers the presence of two stages in the salt crystallization test. In the first, the accumulation stage, salts gradually accumulate on or near the surface of the material due to evaporation. In the second, the propagation stage, damage initiates and develops due to changes in moisture content and relative humidity that trigger salt dissolution and crystallization cycles. To achieve this, two types of salt were tested, namely sodium chloride and sodium sulphate, with each salt tested separately. A methodology for assessing the salt-induced damage is proposed, which includes visual and photographical observations and measurement of material loss. The procedure has been preliminarily validated in round robin tests., Heritage & Architecture

Purpose: Housing interventions carried out in accordance with current regulations in the Old City of Aleppo, both before and after the Syrian war, are minor in comparison to those carried out without a license and illegally. This suggests current policies are inadequate and needs upgrading. Design/methodology/approach: This article critically reviews current Syrian policies and their implementation on residential heritage in the Old City of Aleppo with the aim to identify gaps and propose directions for modifications. Next to a review of the text of official policies and implementation documents, the archive of the Directorate of the Old City has been consulted and license applications, presented in the period 2018–2022, have been examined. Moreover, interviews with decision-makers from academics and practice were conducted. Findings: Major limitations of these policies and relative application procedures have been identified: these involve: legal/administrative, economic and social aspects. Originality/value: The specific needs have been highlighted and some proposals for improvement made., Heritage & Architecture

Plasters and renders used in historic monuments are vulnerable to degradation caused by salt weathering. Crystallisation inhibitors (molecules/ions that alter salt crystallisation) mixed into mortars have shown promising results in mitigating salt damage by inhibiting salt crystallisation, promoting salt transport to the evaporating surface, and modifying crystal habit. However, past research suggests that inhibitors easily leach out from mortars, meaning their long-term positive effect is lost. Encapsulation of an inhibitor within a mortar is a potential solution to minimise leaching. Herein, capsules composed of a polyelectrolyte complex of calcium alginate coated in chitosan are investigated for the controlled diffusive release of sodium ferrocyanide, a known NaCl crystallisation inhibitor. Capsules with varying chitosan-calcium alginate ratios are prepared using the extrusion dripping technique. The release of the inhibitor from capsules in solutions of various pH values ranging from 7–13 is investigated. Results show that increasing the capsule’s chitosan to calcium alginate ratio reduces the inhibitor release for all studied solution pH values compared to pure calcium-alginate capsules. Therefore, a controlled inhibitor release can be obtained by tuning the chitosan-alginate ratio. In future, additional tests will be performed to find suitable capsule compositions for optimising their performance when mixed in mortars., Heritage & Architecture, Materials and Environment

Walls overgrown with plants can have a positive impact on urban comfort and contribute to biodiversity in the city. In particular, quay walls, thanks to their close contact with water, have the potential to be ecologically engineered to encourage the growth of herbaceous plants. Different factors can affect growth of vegetation on walls. This research aims at experimentally investigating the effect of several variables, including quay wall design, building materials and environmental conditions, on receptivity of brick masonry quay walls for herbaceous plants. To this scope, ten quay walls (size 2 m × 2 m x 0.43 m), have been built and placed in a canal in the city of Breda (the Netherlands). The survival and growth of vegetation and the moisture content in the wall were monitored during a period of about 2 years. The results show that the presence of a layer of soil substrate with high capillary suction, positioned in between the masonry cladding and the concrete structure of the wall, has the most relevant positive effect on vegetation growth on the masonry. Mortar composition and irregularities of the wall surface influence bio-receptivity too, but to a less extent; orientation had only a limited effect. Moreover, the strategy of using a mechanically strong bedding mortar in combination with a weaker but more bio-receptive pointing mortar has proven successful at favouring growth of herbaceous plants, while providing sufficient strength to the masonry., Heritage & Architecture, Architectural Technology

Salt crystallization is a major cause of weathering of mortars, including plasters and renders. In the last decade, the use of mixed-in salt crystallization inhibitors in mortars has been proposed as a solution to improve the durability of this material with respect to salt decay. Laboratory characterization and accelerated weathering tests have shown encouraging results. However, data on the long-term behaviour of these mortars when applied on-site were missing until now .In this research the durability with respect to salt decay of a lime-based plaster and a salt accumulating plaster has been assessed. These plasters, with and without sodium ferrocyanide, a well-known inhibitor of sodium chloride crystallization, have been applied to an interior brick masonry wall with a high salt (sodium chloride) and moisture load and monitored for a period of 4 years. Monitoring included visual and photographic observations of the damage as well as measurements of the moisture and salt content and distribution, both in the wall and in the plaster. Moreover, the content and distribution of the inhibitor in the plaster after 4 year exposure was measured, to gain insight into the dissolution and transport of the inhibitor. The results of the research clearly show that the inhibitor is able to significantly reduce the occurrence of salt-induced decay in the lime-based plaster, in comparison to the plaster without inhibitor. No conclusions can be drawn in the case of the salt accumulating plaster, as no decay has developed yet in this case. Two issues related to leaching of the inhibitor and surface discolouration have emerged. These are discussed and possible solutions are proposed., Heritage & Technology

The Adaptive Reuse (AR) of heritage buildings is a complex process, which aims to preserve the values of heritage buildings while adapting them for use in the present and transferring them to the future. This paper aims to identify steps in this process and develop a structured model. The model is an ‘ideal’, it needs validation in practice; however, it is expected that following this model can help to preserve and conserve the values of heritage buildings. To come to an overview of the process and to identify its main steps, a literature review at an international level has been conducted. The analysis of the literature revealed that the AR process as a whole in relation to heritage buildings has not been widely studied. Based on the results of this review, a conceptual model representing the AR process of heritage buildings has been defined. This model consists of 10 steps: ‘initiative’, ‘analysis of heritage buildings’, ‘value assessment, ‘mapping level of significance’, ‘definition of adaptive reuse potential’, ‘definition of design strategy’, ‘final decision-making’, ‘execution’, ‘maintenance’, and ‘evaluation after years’. This model can act as a comprehensive theoretical basis for further studies on the AR process of heritage buildings., Heritage & Technology, Heritage & Design

Adaptive reuse (AR) of heritage buildings is a complex process due to the involvement of many actions and actors, which influence the results of the projects. The effectiveness of AR projects can be described by various criteria. This paper aims to provide a comprehensive overview of the criteria of effectiveness in AR projects with the final scope to guide and improve the AR process. A review of the jury reports of two highly prestigious awards in the Netherlands (NRP Golden Phoenix award) and Europe (Europa Nostra) has been conducted. In total, the reports of 48 cases have been reviewed. The five criteria mentioned in the regulations of the NRP award have been used to categorize the aspects mentioned in the jury reports of both awards. These criteria are: “social value creation”, “sublimation (both architectural and cultural aspects)”, “environmental sustainability”, “economic value creation”, and “innovation”. This review reveals that “social value creation” and “sublimation” are among the most highlighted criteria that the juries considered for the effectiveness of AR projects. Often aspects mentioned for these criteria overlap partially with those aspects mentioned in the criterion of “economic value creation”. This indicates that enhancement of the qualities of heritage buildings and their surroundings and improvement of the social values and the resulting positive economic effects are strictly interrelated. The overview of the criteria of effectiveness, as defined in this work, will serve as a basis for the investigation of the tools and methods which can be used in the AR process to achieve these criteria, Heritage & Technology, Heritage & Design

Salt crystallization is a major cause of damage in porous building materials. Accelerated salt weathering tests carried out in the laboratory are among the most common methods to assess the durability of material to salt decay. However, existing standards and recommendations for salt weathering tests have limitations in terms of effectiveness and/or reliability. In the framework of the RILEM Technical Committee 271-ASC, a procedure has been developed which proposes a new approach to salt crystallization tests. It starts from the consideration that salt damage can be seen as a process developing in two phases: accumulation of the salt in the material and propagation of the decay. In the first phase, salts are introduced in the material and accumulate close to the evaporation surface, while in the second phase damage propagates because of repeated dissolution and crystallization cycles, induced by re-wetting with liquid water and by relative humidity changes. In this paper, the procedure is described and the results of a first round robin validation of the test, carried out on 7 materials and involving 10 laboratories, are presented. The results show that the procedure is effective to cause decay within the time period of the test (about 3 months) and that the decay increases with subsequent cycles. The decay observed differs in type and severity depending on the salt type and concentration and on the type of substrate. The decay types detected in the laboratories are generally representative of those observed in the field for the selected substrates. The differences in durability between the various substrates, as assessed at the end of the test, are in line with the durability expected based on field observation. The reproducibility of the results in terms of decay type is good; some differences have been observed in terms of material loss. These are more significant in the case of NaCl contaminated specimens. Based on the results, proposals for fine-tuning of the p

Adaptive reuse (AR) of modern buildings, including industrial buildings from the late 19th and 20th centuries, is a complex process as it involves many actions and actors, which influence the result of projects. Effective AR can provide many advantages for societies. This paper aims to provide an overview of the three most highlighted criteria, mentioned by previous researchers, for assessing effectiveness of AR of modern buildings. This research followed seven steps: 1.Reviewing the criteria of “effectiveness” in AR projects in the literature 2.Collecting the data (jury reports of NRP and Europa-Nostra awards) 3.Distilling the reports related to modern heritage buildings 4.Translation of Dutch reports in English 5.Analysing and coding the texts following the criteria mentioned in the literature 6.Analysing the role of effective AR of modern heritage buildings in providing sublimation and social value 7.Formulating some conclusions/recommendations. This review indicates despite the attribution of the effectiveness of AR of non-modern heritage buildings to the attraction of tourists, the effectiveness of AR in modern buildings is often attributed to positive effects on the surroundings and local community. Moreover, in modern buildings, compared to non-modern buildings, qualities provided by new interventions are highlighted more. This can be related to open space plans, stronger materials, wider spans, and spacious urban settings providing a higher tolerance for acceptable change. By revealing the aspects of effectiveness within these two criteria, this study contributes to the broader understanding of the AR potential of modern buildings. Though this review is useful for encouraging the reuse of modern buildings, the methods/tools to be used to achieve effective results need more investigation in future research., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Heritage & Technology, Heritage & Design

Salt crystallization is a major cause of damage in porous building materials. Accelerated salt weathering tests carried out in the laboratory are among the most common methods to assess the durability of material to salt decay. However, existing standards and recommendations for salt weathering tests have limitations in terms of effectiveness and/or reliability. In the framework of the RILEM Technical Committee 271-ASC, a procedure has been developed which proposes a new approach to salt crystallization tests. It starts from the consideration that salt damage can be seen as a process developing in two phases: accumulation of the salt in the material and propagation of the decay. In the first phase, salts are introduced in the material and accumulate close to the evaporation surface, while in the second phase damage propagates because of repeated dissolution and crystallization cycles, induced by re-wetting with liquid water and by relative humidity changes. In this paper, the procedure is described and the results of a first round robin validation of the test, carried out on 7 materials and involving 10 laboratories, are presented. The results show that the procedure is effective to cause decay within the time period of the test (about 3 months) and that the decay increases with subsequent cycles. The decay observed differs in type and severity depending on the salt type and concentration and on the type of substrate. The decay types detected in the laboratories are generally representative of those observed in the field for the selected substrates. The differences in durability between the various substrates, as assessed at the end of the test, are in line with the durability expected based on field observation. The reproducibility of the results in terms of decay type is good; some differences have been observed in terms of material loss. These are more significant in the case of NaCl contaminated specimens. Based on the results, proposals for fine-tuning of th, Heritage & Technology

Porous building materials are often subjected to damage due to salt crystallization. In recent years, the addition of crystallization inhibitors in lime-based mortar, has shown promising results in improving durability of this material against salt decay. Lime-based mortars have low mechanical properties and slow setting. They are often replaced with hydraulic binders to overcome these limitations. However, the effect of crystallization inhibitors in mortars with hydraulic binders is still unknown. Incorporation of crystallization inhibitors in hydraulic mortars would widen the application field of this new technology. In this research, the possibility to develop hydraulic mortars with mixed-in sodium ferrocyanide, an inhibitor of sodium chloride crystallization, is explored. As an essential first step, the influence of this inhibitor addition on the properties of hydraulic mortars is investigated. Two common types of hydraulic binders, natural hydraulic lime (NHL) and ordinary Portland cement (CEM I), were studied; the inhibitor was added in different amounts (0%, 0.1% and 1% by binder weight) during mortar (and binder paste) preparation. Relevant mortar and binder paste properties, in fresh (hydration, workability, setting time) and hardened (mechanical strength, elastic modulus, pore size distribution, water absorption) state, were assessed using several complementary methods and techniques. The results indicate that the addition of ferrocyanide does not alter the studied properties of both NHL and CEMI-based mortar and binder pastes. These results are promising for the further development of hydraulic mortars with an improved durability with respect to salt decay., Heritage & Technology, Materials and Environment

Rising damp is a very common phenomenon and one of the most important threats for historical buildings. In this paper two non-invasive systems are studied, the first one is based on the interaction of pulsed electromagnetic waves with the porous materials and the second one is based on the active electro-osmosis principle where the natural difference in electric potential between the walls and the ground is annihilated. Within the light of the debates on the real efficiency against rising damp of such techniques in preservation of historical monuments the last 5 years, the development of such an objective test method and the outcomes of the two tested systems provided important findings for the heritage community., Heritage & Technology

Conservation of built heritage implies the preservation of values, materials and techniques. Interventions in heritage buildings should be minimal, necessary and compatible in aesthetical and technical sense. The quality of the interventions needs to meet intended and agreed-to standards.This book underlines the importance of a sound assessment of the values of a historic building and its technical state of conservation before planning an intervention. How indispensable this step is, is shown by selected examples of building materials and relevant parts of historic buildings. Moisture-induced damage processes and solutions to tackle them have been discussed using the examples of rising damp and surface treatment. The considerations on how and when to maintain and conserve a historic material such as natural stone have been reviewed. The importance of an integrated approach to conservation has been explained, focusing on windows and glazing.Knowledge on specific building materials, building components, damage types and damaging mechanisms as well as methodologies for conservation are presented. The topics have deliberately been chosen to illustrate the wide range of aspects which need to be dealt with in conservation of built heritage. Although discussed from a Western European perspective – as shown by the materials and specific components examined - the aim is to present a valid and broadly applicable approach.Historic monuments conservation demands a specific, transdisciplinary and holistic approach, which can be visualized as a circular decision-making process instead of a linear one, which would benefit the maintenance of non-monumental buildings too. This includes the involvement of owners and end users. The presented methods and methodologies illustrate the possibilities for such a circular approach in research and decision making, when dealing with cultural historical values and technical design solutions.This book has been made to not only transfer knowledg, Heritage & Technology

Deze publicatie is een weerslag van de uitkomsten van het KaDEr-project (Karakteristiek Duurzaam Erfgoed) dat de TU Delft in opdracht van en in samenwerking met de Provincie Gelderland heeft uitgevoerd. De lezer wordt meegenomen in de zoektocht om invulling te geven aan de relatie wetenschap, praktijk en beleid rondom duurzaam erfgoed op verschillende schaalniveaus. Aan de hand van acht bijdragen wordt gereflecteerd op het proces en de uitkomsten. De auteurs gaan in op een thema dat gedurende de afgelopen vier jaar aan de orde is geweest. Ook nemen zij stelling in met betrekking tot het debat dat naar aanleiding van dit thema gevoerd is en in veel gevallen nog verder gevoerd kan worden. Daarnaast hebben we een aantal meer zijdelings betrokkenen gevraagd om stelling te nemen met een uitspraak naar aanleiding van hun ervaringen tijdens het project. Het KaDEr-project omvatte na een intensieve voorbereiding vier kalenderjaren. We denken dat op het onderdelen nog een vervolg behoeft. KaDEr staat dus voor Karakteristiek Duurzaam Erfgoed en in het project is gewerkt aan energetische duurzaamheid, financieel gezond perspectief, functioneel gebruik en het borgen kennis op lange termijn. Het project zelf werd opgebouwd rond vier Living Labs om theorie en praktijk aan elkaar te koppelen:  Living Lab XL-Stad: Zutphen, Winterswijk en Elburg. Daarbij droegen we vanuit KaDEr bij aan een onderzoek naar Kerkenvisies en de Energietransitie voor diverse gemeenten;  Living Lab L-Stad: Landgoederen, waar het Baaksebeek-gebied en Gelders Arcadië centraal stonden en het onderzoek resulteerde in de betreffende Ontwerpatlas;  Living Lab M-Typologie: Kerken. Nationaal en regionaal een opgave die veel aandacht kreeg de afgelopen vier jaar. Specifiek keken wij vanuit KaDEr naar het functioneren van Energiescans en de Financiële Duurzaamheid aan de hand van de Eusebiuskerk in Arnhem en de Stevenskerk in Nijmegen;  Living Lab S-Gebouw: Reuversweerd. Een (bouw)loca, Heritage & Design, Landscape Architecture, Heritage & Technology, Real Estate Management, Climate Design and Sustainability

Historic concrete buildings are at risk. Limited knowledge of concrete technology until the 1960s led to more sensitive buildings than modern concrete buildings. In addition, the lack of sensibility regarding their heritage value and insufficient protection is leading to remorseless demolition. Still, concrete has proved to be a resilient material that can last over a century with proper care. There is not yet an estimation of the status of historic concrete buildings in Europe. Until now, a few attempts have been done to secondarily, and subjectively, gauge their conservation status. This paper is the result of a joint investigation studying forty-eight historic concrete buildings distributed in four countries. They were surveyed by expert teams according to a predefined methodology. The study aims to identify recurrent damages and parameters affecting the conservation state. It also aims to serve as the first trial for an objective and measurable methodology, to apply it with a statistically significant number of cases. Damages related to the corrosion of reinforcement and moisture-related processes were the most recurrent. The use of plasters, flat roofs, and structural façade walls show a positive effect in protecting the concrete. The state of conservation has a great variability across countries., Heritage & Technology

Compatibility of repair materials in conservation is a widely desired goal, but difficult to achieve. In this research, the compatibility of four commercial stone repair mortars, commonly used in conservation practice in the Netherlands and neighbouring countries, is discussed. In order to do so, they have been characterized in laboratory. The composition of the repair mortars, their content of soluble salts, porosity and pore size distribution, hygric dilation and flexural and compressive strength were measured. The effect of curing was assessed by comparing specimens cured in laboratory and under outdoor conditions. The effect of 3 years outdoor exposure on the curing and weathering of the mortars was evaluated. The results show that the composition of the selected mortars varies significantly, even though, based on their technical information sheets, they appeared to be similar. Consequently, their moisture transport properties differ significantly. As expected, both the type of binder and the porosity were shown to affect the mechanical properties of the mortar: the mortar based on an inorganic polymer binder showed the highest mechanical strength; the most porous, lime- or lime-cement-based mortars, showed the lowest mechanical strength. Based on compatibility criteria defined in literature and the results obtained in this research, an attempt was made to assess the technical compatibility of the selected mortars with building stones commonly used in the Netherlands. It was found that some requirements are hard to be fulfilled and not all requirements can be fulfilled at the same time. Besides, technical sheets of commercial mortars are often incomplete; therefore repair mortars can hardly be selected based only on the properties reported by the producers., Heritage & Technology

The rehabilitation and sustainable transformation of residential heritage of the Old City of Aleppo (Syria) is one of the most pressing issues to regain the livability of this city. This research paper aims to gain insight into the residents’ conditions and needs by studying/mapping/analyzing the status of the residential heritage and the interventions on it during the aftermath of the city’s devastation. It also intends to provide a better understanding of the residents’ attitude towards living in the Old City, their expectation for its reconstruction and transformation, and the difficulties they encountered in the process. In fact, in order to start a collective reconstruction and transformation process, it is important to understand the readiness of the inhabitants and their financial capabilities to engage in this process. A combination of research methods was used to explore the above-mentioned issues and their relation to the socio-cultural sustainability. These methods included: gathering data in the field (specifically, Al-Jalloum, Al-Farafra and Al-Aqaba, three neighborhoods in the Old City of Aleppo, were used as case studies), and setting up a questionnaire (Winter 2020) and conducting interviews (Summer 2021) with 39 returnees and their families. AutoCAD and Excel programs were used for data visualization. This research has highlighted the main problems and factors that have affected the interventions on courtyard houses in the Old City of Aleppo since 2012—the outbreak of the Syrian War in Aleppo City. Lack of funds and craftmanship, high costs and long bureaucratic procedures related to the enforcement of the regulations have been identified as the main causes that discouraged the residents to carry out repairs in a proper way, Heritage & Technology

Historic concrete buildings (end of 19th century – 1960s), because of their “experimental” character, require a specific approach to both survey and conservation. Although they were built with empirical approaches, some buildings show a fair state of conservation and resilience –even though they have already exceeded the 100-year threshold– while others of comparable age are in severe need of restoration. As part of the European project CONSECH20, aimed at contributing to the conservation of cultural-heritage concrete buildings, this paper investigates what are the most common types of damage and hypothetical causes, and what direct and non-direct parameters can lead to a faster or slower deterioration of historic concrete in the Netherlands. The research is based on an initial screening study, which will be used as a basis for a larger research among the participant countries. The current research is divided in three phases. Firstly, a selection of 15 case studies from the Netherlands are investigated; the selection was based on criteria of age, state of conservation and type of ownership. Secondly, the history and materials of the buildings are examined. Thirdly, an on-site visual survey is performed per each building, with pre-design templates, to identify types of damage, extent and severity. The data is then analysed combining different factors with a calculated index of severity. Results are discussed and contrasted to provide further clarification of the degradation of historic concrete. A fourth phase, not discussed in this paper, will use this methodology in a broader context, with a larger number of case studies in different countries., Heritage & Technology

Sodium chloride (NaCl) is one of the ubiquitous soluble salts in the environment and is responsible for weathering of building materials. The salt weathering is attributed to the stress developed from crystallisation of these salts in pores of the building materials, with supersaturation as the driving force. In the last years, researchers have successfully mitigated the damage associated with the crystallisa-tion of NaCl by the use of alkali-ferrocyanides (crystallisation inhibitors) in porous building materials. The observed mitigation of the damage has been attributed to lowering of the crystallisation pressure, possibly related to changes in the crystal habit and preferential crystallisation of the salt in the form of efflorescence instead of crypto-florescence. However, the effect of the inhibitor on the development of the so-called crystallisation pressure has not been studied in detail yet. In fact, direct measurement of this pressure is challenging and, until now, only a few experiments have been successful. In this research, an experimental setup has been developed to directly measure the crystallisation forces of NaCl and the effect of fer-rocyanide on these, while visualizing the crystallization process under a microscope. Some preliminary tests using this setup have been carried out: these consisted in monitoring force evolution from a drop of solution with and without the inhibitor confined between two glass plates., Heritage & Technology, Materials and Environment

The RILEM TC 271-ASC is currently developing a new ageing test to assess the resistance of porous building materials to salt crystallisation. The new test consists of two phases: salt accumulation and damage propagation. This paper focuses on the salt accumulation phase; this phase should promote salt crystallisation close to the evaporative surface of the substrates (common situation onsite) without leading to salt efflorescence or damage. Damage should take place in the propagation phase, which is not addressed in this paper. This work compares the effectiveness of three contamination procedures for salt accumulation: P1) salt contamination by capillary absorption of salt solution, followed by drying; P2) continuous capillary absorption of salt solution; P3) placement of salt crystals on the surface of the materials followed by the conditioning of the specimens at high relative humidity until complete dissolution of the salts. The results of P1 and P2 procedures presented in this paper are detailed in a separate publication, while this paper focuses on P3 procedure and compares the results. The effectiveness of each procedure has been evaluated by assessing the salt distribution in the specimen using ion chromatography and scanning electron microscopy. The results show that P3 is technically the least complicated to set up and does not entail the risk of development of salt efflorescence or damage. However, it can lead to salt migration within the specimens to a greater depth, hence future research is proposed to counteract this effect., Heritage & Technology

The RILEM Technical Committee 271-ASC was set up in 2016 with the aim of developing an improved procedure for the assessment of the durability of porous building materials, such as brick and natural stone, against salt crystallization, accelerating the deterioration process without significantly altering its mechanism. The test procedure developed by the TC 271-ASC proposes a new approach to salt crystallization tests. It starts from the consideration that it is necessary to accumulate a certain amount of salt to activate the damage. Thus salt damage can be seen as a process developing in two phases: accumulation and propagation. Based on this approach, a new salt crystallization test procedure has been defined, consisting of two phases: a first phase, in which salts are introduced in the material and accumulate close to the evaporation surface, followed by a second phase, in which damage propagates because of repeated dissolution and crystallization cycles induced by re-wetting with liquid water and by relative humidity (RH) changes. In this paper the procedure is described and the reasons for the choices made are elucidated. The procedure has been tested on two types of limestone and, at the moment of writing, is being validated in a round robin test carried out on 9 different substrates and involving 11 laboratories. Based on the results of the round robin test, the procedure will be fine-tuned., Heritage & Technology

The RILEM TC ASC-271 is developing a new laboratory test to assess the durability of porous building materials to salt crystallisation. The test encompasses two phases: salt accumulation and damage propagation. This paper focuses on designing a procedure for the accumulation phase; this is considered successful when salts crystallise at the material's evaporative surface (common situation observed on site) without the occurrence of damage. Two procedures were developed and tested on two limestones with different porosity: (1) capillary absorption of a salt solution followed by drying, and (2) continuous capillary absorption. Sodium chloride or sodium sulphate solutions were used. Several methods for assessing the salt distribution were employed: ultrasonic pulse velocity, drilling/scratching resistance, hygroscopic moisture content, ion chromatography, scanning electron microscopy, and micro X-ray fluorescence. The results enabled the selection of the most effective protocol for the salt accumulation phase., Heritage & Technology

The effect of mortar and brick properties on the growth of ivy-leaved toadflax (Cymbalaria muralis) and yellow corydalis (Pseudofumaria lutea) has been investigated in laboratory. Different mortar compositions were designed and tested in combination with two different bricks. Highly porous bricks and mortars showed good bioreceptivity; mortars with lime-trass and, in lower extent, those with natural hydraulic lime binder, gave the best results in terms of bioreceptivity. The addition of vermiculite to the mortar was beneficial for plant growth. The brick-mortar combinations most favourable for plant growth were those with estimated low compressive and flexural bond strength values. Proposals are advanced for obtaining a compromise between mechanical strength and bioreceptivity., Heritage & Technology, Design of Constrution, Applied Mechanics