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Renders and plasters have significant functions in buildings. Their functionality is closely related to their properties, which depend on the mortar itself, the application technology, the interaction with the environment and the substrate. There are many basic characteristics that influence the performance of renders and plasters; however, many of them are interrelated, thus the set of characteristics to be determined in each case is different, depending on the specific at each time use. These characteristics, their interrelations and the grouping of them are discussed and schematically described in the first and introductory section. Three groups are considered for renders and plasters: properties of fresh mortars; properties related to the hygric behaviour; and the mechanical behaviour. The properties of lime-based mortars measured in laboratory are highly affected by factors, such as: need of long time for development of representative values for prediction of their life-time behaviour, proper climatic conditions adequate for carbonation or/and hydration, sensitivity to the suction of water by the substrate. The last two factors—environment and substrate—have an important role for rendering and plastering with lime-based mortars, since both their exposed surfaces and the substrate areas they cover are large. Due to those specificities, the current test methods that have been mainly developed for cement-based mortars are not always fitted to characterize lime-based mortars, and in particular to assess lime-based renders and plasters. In section two the main characteristics and current standardized test methods are discussed based on experience in using them. Furthermore, needs of improvement are identified and changes are proposed, or, in some cases, new methods are outlined. Some of the most significant changes proposed are the possibility, as an option, to apply the mortar on a porous substrate, instead of moulding specimens in metallic moulds, together with, 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

Historic Structures are commonly coated with mortar layers (plasters, renders, flooring) for protection and decoration. These well finished architectural stratigraphic surfaces often suffer from deterioration, such as lack of adhesion or detachment between support and mortar layers and even between mortar layers. Grouting and filling voids between delaminated layers can be an effective intervention if the layers are compact. This paper deals with aspects pertinent to the selection, design and implementation of a grout for the in situ stabilization and preservation of historic architectural surfaces. It presents the methodological approach, in accordance with the conservation principles, including sections on diagnosis, study and assessment of the deterioration phenomena, definition of grout requirements, selection of proper ingredients for custom-made or commercial grouts, as well as making and testing trial mixes, field testing and Assessment of the effectiveness of grouting. The aim of this paper, that is elaborated in the frame of RILEM TC 243 SGM, is to serve as a guide for users of lime-based grouts for the reattachment and reinstatement of historical architectural surfaces., 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., Applied Mechanics, Heritage & Technology

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

For conservation interventions of historic masonry generally lime-based mortars such as pure air lime mortars, lime-pozzolan mortars, natural hydraulic lime mortars and ternary mortars (lime-pozzolan-cement) are used. The main reason is that their hygric and mechanical (strength and ductility) performance are easy to adapt to most existing historic masonry (compatibility requirements). Although the basic appropriateness of lime-based mortars for restoration is undisputed, there are also some limitations in the application of these mortars. In this report a review is given of the theoretical backgrounds and further of laboratory research developments in the field of lime-based binders and mortars over the past decades. Furthermore, practical experiences in positive and negative sense (damage cases) are elaborated. Drawbacks and points of attention are being dealt with, which are essential for a durable application of lime-based mortars for the conservation of historic masonry. In general, it is concluded that points of attention should be addressed through a thorough evaluation of their potential and through testing of their suitability. For these mortars, even more than for modern cement-based mortars, specifically, environmental exposure conditions and application conditions should be considered., Applied Mechanics, 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

In the Netherlands a program for the enhancement of quality in the restoration of monumental buildings is presently carried out, stimulated by national authorities and coordinated by the foundation ERM. Guidelines are issued by the branches involved, from architects to masons, under guidance of an experts’ committee, to perform interventions on monuments and assess them. The aim of this paper is to discuss the contributions to the program offered by different actors active in the field of conservation, the existing synergies and the potential of using a common language and approach. These are needed to facilitate communication and exchange knowledge. The use of the terminology of MDCS (Monument Diagnosis and Conservation System) can help create a community of stakeholders. Sharing the damage terminology and methodology can help achieving a clear and systematic assessment of damage and its causes. It can further improve the communication among all stakeholders, including owners and laymen, stimulating cooperation, and can allow monitoring of damage and interventions., Heritage & Technology

Het blussen van een brand gaat gepaard met een grote hoeveelheid water die in het metselwerk van een gebouw binnendringt; daarnaast duurt het vaak ook nog lange tijd voor een gebouw weer waterdicht kan worden gemaakt. Dit kan een hoog vochtgehalte in de muren veroorzaken, met alle daaraan verbonden problemen, zoals zouttransport, zout- en vorstschade en biologische groei. In dit artikel wordt de casus van de Neo-classicistische Elleboogkerk te Amersfoort besproken, waarvan de kapconstructie in 2007 door een brand werd verwoest. Naast directe schade door de brand aan het gebouw en de daarin aanwezige museale collectie, ontstond er ook vervolgschade als gevolg van vocht. Onderzoek toonde aan dat een hoog vochtgehalte in de muren, in de nasleep van de brand, de oorzaak is geweest van het loskomen van het nieuwe pleisterwerk, binnen enkele weken nadat dit was aangebracht. Daarnaast maakte het onderzoek het mogelijk om, op basis van het gemeten zoutgehalte in de muur, het risico voor het verder ontstaan van schade in te schatten en advies te geven over het wel of niet vervangen van de (nog) niet beschadigde delen van het renovatiepleisterwerk., 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, Heritage & Technology

In the Netherlands a program for the enhancement of quality in the restoration of monumental buildings is presently carried out, stimulated by national authorities and coordinated by the foundation ERM. Guidelines are issued by the branches involved, from architects to masons, under guidance of an experts’ committee, to perform interventions on monuments and assess them. The aim of this paper is to discuss the contributions to the program offered by different actors active in the field of conservation, the existing synergies and the potential of using a common language and approach. These are needed to facilitate communication and exchange knowledge. The use of the terminology of MDCS (Monument Diagnosis and Conservation System) can help create a community of stakeholders. Sharing the damage terminology and methodology can help achieving a clear and systematic assessment of damage and its causes. It can further improve the communication among all stakeholders, including owners and laymen, stimulating cooperation, and can allow monitoring of damage and interventions., 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 Rietveld Schröder House is not only an icon of Dutch architecture, but also a museum welcoming about 18,000 visitors each year. The unusual experimental character of the construction and the fact that the house is open to the public can be expected to affect the indoor climate and to pose some risks for the conservation of the building and the furniture. In order to assess possible risks related to the indoor climate and, if necessary, take measures, a monitoring of the indoor climate was carried out in 2017., Heritage & Technology

Surface repair mortars are used for the compensation, or repair, of lost portions of surface materials in historic masonry buildings. It is recommended that their design and application should be performed in a wider context of conservation values related decision making, to prioritise preservation of original fabric, authenticity of approach and maintenance of integrity, and not just on technical principles alone. However, a technical context for their design does exist, that requires understanding of the properties of the substrate that they will be applied onto, and adherence to minimum aesthetic (colour and texture) requirements. The principles of physical, mechanical and chemical compatibility of repair apply and the attributes of the repair mortar should be carefully matched to the substrate alongside a sacrificial behaviour (not more durable than the material being replaced). Guidance is given on the design, application and the functional requirements that must be met when using surface repair mortars., Accepted Author Manuscript, Heritage & Technology

Weathering of porous building materials caused by the crystallization of soluble salts is a ubiquitous problem in the built cultural heritage. Especially lime-based mortars are susceptible to salt decay, due to both their bimodal pore size distribution and low mechanical strength. The addition of crystallization modifiers to mortars during mixing may confer them an improved resistance to salt decay. In this research, lime-based mortars additivated with ferrocyanide or borax (modifiers for sodium chloride and sodium sulfate, respectively) were prepared. An accelerated salt crystallization test was carried out to assess the effect of the modifiers on the salt resistance of the mortars. The development of damage was assessed by visual and photographical observations and by quantifying the salt and material loss. At the end of the test, SEM observations were performed on the surface and cross-section of the specimens, to study the effect of the modifiers on the crystallization habit of the salts. The ferrocyanide and borax additivated mortars showed a considerably improved durability with respect to salt crystallization damage. Both modifiers altered the growth morphology of the salt crystals inside the pores of the mortars., Accepted Author Manuscript, Heritage & Technology

Surface repair mortars are used for the compensation, or repair, of lost portions of surface materials in historic masonry buildings. It is recommended that their design and application should be performed in a wider context of conservation values related decision making, to prioritise preservation of original fabric, authenticity of approach and maintenance of integrity, and not just on technical principles alone. However, a technical context for their design does exist, that requires understanding of the properties of the substrate that they will be applied onto, and adherence to minimum aesthetic (colour and texture) requirements. The principles of physical, mechanical and chemical compatibility of repair apply and the attributes of the repair mortar should be carefully matched to the substrate alongside a sacrificial behaviour (not more durable than the material being replaced). Guidance is given on the design, application and the functional requirements that must be met when using surface repair mortars., Accepted Author Manuscript, Heritage & Technology

The Rietveld Schröder House is not only an icon of Dutch architecture, but also a museum welcoming about 18,000 visitors each year. The unusual experimental character of the construction and the fact that the house is open to the public can be expected to affect the indoor climate and to pose some risks for the conservation of the building and the furniture. In order to assess possible risks related to the indoor climate and, if necessary, take measures, a monitoring of the indoor climate was carried out in 2017., Heritage & Technology

Weathering of porous building materials caused by the crystallization of soluble salts is a ubiquitous problem in the built cultural heritage. Especially lime-based mortars are susceptible to salt decay, due to both their bimodal pore size distribution and low mechanical strength. The addition of crystallization modifiers to mortars during mixing may confer them an improved resistance to salt decay. In this research, lime-based mortars additivated with ferrocyanide or borax (modifiers for sodium chloride and sodium sulfate, respectively) were prepared. An accelerated salt crystallization test was carried out to assess the effect of the modifiers on the salt resistance of the mortars. The development of damage was assessed by visual and photographical observations and by quantifying the salt and material loss. At the end of the test, SEM observations were performed on the surface and cross-section of the specimens, to study the effect of the modifiers on the crystallization habit of the salts. The ferrocyanide and borax additivated mortars showed a considerably improved durability with respect to salt crystallization damage. Both modifiers altered the growth morphology of the salt crystals inside the pores of the mortars., Accepted Author Manuscript, Heritage & Technology

Naar aanleiding van het historisch georiënteerde onderzoek naar oppervlaktebehandelingen (Nijland & Quist 2018) en het onderzoek naar het hervoegen van gehydrofobeerd metselwerk, beide uitgevoerd binnen de samenwerking tussen TNO, RCE en TU Delft in MonumentenKennis, ontstond het idee om aan de hand van een aantal casussen te kijken naar de duurzaamheid van hydrofoberingen. Voor de keuze van de casussen is teruggegrepen op twee onderzoeken/publicaties uit de jaren ’90 van de vorige eeuw waarin de prestatie van hydrofoberingen werd onderzocht (Van Hees & Koek 1994, Van Hees et al. 1998). Een aantal objecten dat in deze studies is onderzocht is in juni 2018 opnieuw bezocht en bij een deel van deze objecten zijn in november 2018 Karstenbuismetingen verricht om de waterabsorptie van de (bak)steen en het voegwerk te meten., Heritage & Technology

The injection of chemical products, meant to penetrate in the capillaries of the materials composing an affected wall, is perhaps the most diffused method to deal with rising damp. The majority of these chemical products are hydrophobic treatments; they can be either solvent-based or (increasingly) water-based. Traditionally, these products are liquid. In the last years however, a tendency towards the use of cream-like products can be observed. From practice, quite contradictory opinions arrive with respect to the effectiveness of injections and quite often disputes develop between building owner and executing contractor on the performance of the treatment. Sometimes the slow drying of humid walls is used to cover a failing treatment; in other cases, it is not clear whether the injection or a simultaneously applied restoration plaster is responsible for a visual improvement. Research was performed in order to establish a method to evaluate the effectiveness of injection methods in a simple and quick way, both for assessing performance in practice and for use in laboratory. Interesting side effect of the research program was that also several essential parameters, influencing the effectiveness of chemical products, became evident. In this article, focus will be on the quick assessment method for practice., Accepted Author Manuscript, Heritage & Technology, Education and Student Affairs

In deze bijdrage wordt nader ingegaan op de achtergronden van zoutschade, de vraag of we er in de toekomst meer last van zullen krijgen, en op oud, nieuw en gewenst onderzoek., Heritage & Technology

The durability of building materials with respect to salt crystallization is commonly determined by accelerated weathering tests, carried out in the laboratory. An effective laboratory weathering test should assess the durability and, in the case of conservation of historic buildings, the compatibility of repair materials with those existing. Besides, the test should provide reliable results within a reasonable period of time, accelerating the deterioration process without however altering its mechanism. Despite several national and international standards, recommendations and guidelines, a commonly accepted testing protocol does not yet exist. Researchers often develop and apply their own procedure, a fact that complicates comparison between different studies. The RILEM Technical Committee 271 ASC has been set up with the scope of developing improved test procedures for the assessment of the behaviour of materials under the influence of salt crystallization, which should overcome the limitations of existing standards and recommendations. This paper constitutes one of the first results of the work of the Technical Committee. It critically reviews the literature on salt crystallization tests, identifies advantages and limitations of the several test protocols and provides new ideas for the development of improved salt crystallization procedures., Heritage & Technology

Rising damp is a recurrent hazard to ancient buildings in Europe and its relevance is expected to increase in the future, due to climate changes. The presence of rising damp in walls does not only create an unpleasant climate in buildings, but it also enhances damage processes such as frost action, salt crystallization and biological growth, with possible consequences on the health of the inhabitants. The relevance of this problem is reflected by the large variety of products on the market. The wide and differentiated offer and the scarce scientific information on the effectiveness of the methods make it difficult, (even) for professionals working in the field, to choose a suitable intervention on a sound basis. The JPICH-financed project EMERISDA (2014–2017) [1] aimed at evaluating the effectiveness of different intervention methods against rising damp. The project involved universities, research institutes, heritage agencies and companies (producers and contractors) in Belgium (BBRI, co-ordinator), Italy (CNR-ISAC, Universita’ Ca’ Foscari Venezia, Restauri Speciali s.r.l., Diasen s.r.l.) and The Netherlands (Delft University of Technology and the Cultural Heritage Agency of the Netherlands). The research methodology included the use of an on-line questionnaire and experimental research in laboratory, on scale models and on-site. Both traditional methods, such as chemical injection, and more recent techniques, such as the so-called “electro-physical” methods have been investigated. [2] The following results of the EMERISDA project are presented in this paper: - Results from on-line questionnaire.- Definition of an experimental procedure for the assessment of the presence of rising damp and of the effectiveness of the intervention.- Prototype of decision support tool, which provides insight into the feasibility and risks of existing methods against rising damp and supports actors involved in conservation in the choice and application of the methods against rising, Accepted Author Manuscript, Heritage & Technology

In deze bijdrage worden de belangrijkste bevindingen gerelateerd aan het effect van toevoeging van de modificatoren op morteleigenschappen en op de duurzaamheid van de mortels gerapporteerd. Allereerst wordt er een experiment beschreven waarin wordt getest of de effectiviteit van borax wordt beïnvloed door het carbonatatieproces. Vervolgens worden de effecten van de modificatoren op morteleigenschappen zoals verwerkbaarheid, waterabsorptie en droging, en buig- en druksterkte gerapporteerd. Als laatste wordt de weerstand van de mortels met modificatoren tegen zoutschade bediscussieerd aan de hand van resultaten van een versnelde zoutkristallisatietest., Heritage & Technology

Additivating mortars with crystallization modifiers is a novel approach to mitigate salt crystallization damage in historic masonry. Once verified the effectiveness of crystallization modifiers in bulk solution, the next step consists in verifying whether: (i) modifiers are still effective when mixed in mortar and going through the carbonation process and (ii) modifiers alter any mortar properties which might limit their application. This research addresses these issues for sodium ferrocyanide and borax, modifiers for sodium chloride, and sodium sulfate, respectively. Several experimental techniques have been applied to elucidate these questions. The results show that the selected modifiers are still able to alter the salt crystallization after going through the carbonation process of the mortar. Besides, no major effects of the modifiers on the fresh and hardened mortar properties were observed. It can therefore be concluded that there are no restraints for the future use of these crystallization modifiers in restoration mortars., Heritage & Technology

Optrekkend vocht is een vaak voorkomend fenomeen in gebouwen. Vooral oude gebouwen die geen waterkerende laag (zoals bijvoorbeeld een trasraam) hebben, lijden aan dit probleem. De relevantie van optrekkend vocht blijkt ook uit het grote aanbod van producten voor het bestrijden van dit probleem. Het grote, gevarieerde aanbod en de beperkte literatuur over de effectiviteit van de bestrijdingsmethoden maken het moeilijk voor mensen werkzaam in de praktijk om een keuze te maken tussen de verschillende methoden. Binnen het project EMERISDA, gefinancierd door het Europese Joint Program Initiative Cultural Heritage (JPI-CH), is onderzoek uitgevoerd naar de effectiviteit van de verschillende methoden met als uiteindelijke doel een beslissingssysteem te ontwikkelen ter ondersteuning van de praktijk. Het onderzoek bestond uit literatuuronderzoek, een online enquête om de tevredenheid van de gebruiker (gebouweigenaren en instanties werkzaam in de conservering van cultureel erfgoed) te meten en experimenteel onderzoek in het laboratorium en in situ (aan schaalmodellen en aan gebouwen). De resultaten van het project zijn samengebracht in een digitaal beslissingssysteem. Dit systeem is ontwikkeld om gebruikers te ondersteunen in het vaststellen van de aanwezigheid van optrekkend vocht in gebouwen en in het kiezen van een geschikte interventie., Heritage & Technology

Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische, Heritage & Technology, Education and Student Affairs

In deze bijdrage wordt nader ingegaan op de achtergronden van zoutschade, de vraag of we er in de toekomst meer last van zullen krijgen, en op oud, nieuw en gewenst onderzoek., Heritage & Technology

Naar aanleiding van het historisch georiënteerde onderzoek naar oppervlaktebehandelingen (Nijland & Quist 2018) en het onderzoek naar het hervoegen van gehydrofobeerd metselwerk, beide uitgevoerd binnen de samenwerking tussen TNO, RCE en TU Delft in MonumentenKennis, ontstond het idee om aan de hand van een aantal casussen te kijken naar de duurzaamheid van hydrofoberingen. Voor de keuze van de casussen is teruggegrepen op twee onderzoeken/publicaties uit de jaren ’90 van de vorige eeuw waarin de prestatie van hydrofoberingen werd onderzocht (Van Hees & Koek 1994, Van Hees et al. 1998). Een aantal objecten dat in deze studies is onderzocht is in juni 2018 opnieuw bezocht en bij een deel van deze objecten zijn in november 2018 Karstenbuismetingen verricht om de waterabsorptie van de (bak)steen en het voegwerk te meten., Heritage & Technology

Additivating mortars with crystallization modifiers is a novel approach to mitigate salt crystallization damage in historic masonry. Once verified the effectiveness of crystallization modifiers in bulk solution, the next step consists in verifying whether: (i) modifiers are still effective when mixed in mortar and going through the carbonation process and (ii) modifiers alter any mortar properties which might limit their application. This research addresses these issues for sodium ferrocyanide and borax, modifiers for sodium chloride, and sodium sulfate, respectively. Several experimental techniques have been applied to elucidate these questions. The results show that the selected modifiers are still able to alter the salt crystallization after going through the carbonation process of the mortar. Besides, no major effects of the modifiers on the fresh and hardened mortar properties were observed. It can therefore be concluded that there are no restraints for the future use of these crystallization modifiers in restoration mortars., Heritage & Technology

In deze bijdrage worden de belangrijkste bevindingen gerelateerd aan het effect van toevoeging van de modificatoren op morteleigenschappen en op de duurzaamheid van de mortels gerapporteerd. Allereerst wordt er een experiment beschreven waarin wordt getest of de effectiviteit van borax wordt beïnvloed door het carbonatatieproces. Vervolgens worden de effecten van de modificatoren op morteleigenschappen zoals verwerkbaarheid, waterabsorptie en droging, en buig- en druksterkte gerapporteerd. Als laatste wordt de weerstand van de mortels met modificatoren tegen zoutschade bediscussieerd aan de hand van resultaten van een versnelde zoutkristallisatietest., Heritage & Technology

Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische producten is wellicht de meest verbreide methode om optrekkend Injectie van chemische, Heritage & Technology, Education and Student Affairs

The injection of chemical products, meant to penetrate in the capillaries of the materials composing an affected wall, is perhaps the most diffused method to deal with rising damp. The majority of these chemical products are hydrophobic treatments; they can be either solvent-based or (increasingly) water-based. Traditionally, these products are liquid. In the last years however, a tendency towards the use of cream-like products can be observed. From practice, quite contradictory opinions arrive with respect to the effectiveness of injections and quite often disputes develop between building owner and executing contractor on the performance of the treatment. Sometimes the slow drying of humid walls is used to cover a failing treatment; in other cases, it is not clear whether the injection or a simultaneously applied restoration plaster is responsible for a visual improvement. Research was performed in order to establish a method to evaluate the effectiveness of injection methods in a simple and quick way, both for assessing performance in practice and for use in laboratory. Interesting side effect of the research program was that also several essential parameters, influencing the effectiveness of chemical products, became evident. In this article, focus will be on the quick assessment method for practice., Accepted Author Manuscript, Heritage & Technology, Education and Student Affairs

Optrekkend vocht is een vaak voorkomend fenomeen in gebouwen. Vooral oude gebouwen die geen waterkerende laag (zoals bijvoorbeeld een trasraam) hebben, lijden aan dit probleem. De relevantie van optrekkend vocht blijkt ook uit het grote aanbod van producten voor het bestrijden van dit probleem. Het grote, gevarieerde aanbod en de beperkte literatuur over de effectiviteit van de bestrijdingsmethoden maken het moeilijk voor mensen werkzaam in de praktijk om een keuze te maken tussen de verschillende methoden. Binnen het project EMERISDA, gefinancierd door het Europese Joint Program Initiative Cultural Heritage (JPI-CH), is onderzoek uitgevoerd naar de effectiviteit van de verschillende methoden met als uiteindelijke doel een beslissingssysteem te ontwikkelen ter ondersteuning van de praktijk. Het onderzoek bestond uit literatuuronderzoek, een online enquête om de tevredenheid van de gebruiker (gebouweigenaren en instanties werkzaam in de conservering van cultureel erfgoed) te meten en experimenteel onderzoek in het laboratorium en in situ (aan schaalmodellen en aan gebouwen). De resultaten van het project zijn samengebracht in een digitaal beslissingssysteem. Dit systeem is ontwikkeld om gebruikers te ondersteunen in het vaststellen van de aanwezigheid van optrekkend vocht in gebouwen en in het kiezen van een geschikte interventie., Heritage & Technology

The durability of building materials with respect to salt crystallization is commonly determined by accelerated weathering tests, carried out in the laboratory. An effective laboratory weathering test should assess the durability and, in the case of conservation of historic buildings, the compatibility of repair materials with those existing. Besides, the test should provide reliable results within a reasonable period of time, accelerating the deterioration process without however altering its mechanism. Despite several national and international standards, recommendations and guidelines, a commonly accepted testing protocol does not yet exist. Researchers often develop and apply their own procedure, a fact that complicates comparison between different studies. The RILEM Technical Committee 271 ASC has been set up with the scope of developing improved test procedures for the assessment of the behaviour of materials under the influence of salt crystallization, which should overcome the limitations of existing standards and recommendations. This paper constitutes one of the first results of the work of the Technical Committee. It critically reviews the literature on salt crystallization tests, identifies advantages and limitations of the several test protocols and provides new ideas for the development of improved salt crystallization procedures., Heritage & Technology

Rising damp is a recurrent hazard to ancient buildings in Europe and its relevance is expected to increase in the future, due to climate changes. The presence of rising damp in walls does not only create an unpleasant climate in buildings, but it also enhances damage processes such as frost action, salt crystallization and biological growth, with possible consequences on the health of the inhabitants. The relevance of this problem is reflected by the large variety of products on the market. The wide and differentiated offer and the scarce scientific information on the effectiveness of the methods make it difficult, (even) for professionals working in the field, to choose a suitable intervention on a sound basis. The JPICH-financed project EMERISDA (2014–2017) [1] aimed at evaluating the effectiveness of different intervention methods against rising damp. The project involved universities, research institutes, heritage agencies and companies (producers and contractors) in Belgium (BBRI, co-ordinator), Italy (CNR-ISAC, Universita’ Ca’ Foscari Venezia, Restauri Speciali s.r.l., Diasen s.r.l.) and The Netherlands (Delft University of Technology and the Cultural Heritage Agency of the Netherlands). The research methodology included the use of an on-line questionnaire and experimental research in laboratory, on scale models and on-site. Both traditional methods, such as chemical injection, and more recent techniques, such as the so-called “electro-physical” methods have been investigated. [2] The following results of the EMERISDA project are presented in this paper: - Results from on-line questionnaire.- Definition of an experimental procedure for the assessment of the presence of rising damp and of the effectiveness of the intervention.- Prototype of decision support tool, which provides insight into the feasibility and risks of existing methods against rising damp and supports actors involved in conservation in the choice and application of the methods against rising, Accepted Author Manuscript, Heritage & Technology

Borax has been identified as a possible crystallization modifier for sodium sulfate. Understanding the effect of borax on factors influencing transport and crystallization kinetics of sodium sulfate helps to clarify how this modifier might limit crystallization damage. It has been observed that the addition of borax to sodium sulfate solutions has no influence on the wetting properties (contact angle on glass, surface tension, or evaporation rate) and therefore will not influence solution transport. Additionally, the influence of borax on the crystallization kinetics of sodium sulfate was studied under controlled environmental conditions. This was carried out in mixtures in glass microcapillaries, and sequentially in droplets on glass plates. Under the here studied precipitation conditions, the addition of borax has no influence on the supersaturation ratio at the onset of crystallization, but it significantly affects the crystallization pattern of anhydrous sodium sulfate crystals (thenardite). Using RAMAN spectroscopy, two different hydrates of borax were identified after precipitation, depending on the initial concentration of the solution. Each hydrate has a different effect on the subsequent crystallization of sodium sulfate. The decahydrate polymorph of borax leads to the precipitation of hydrated sodium sulfate crystals (mirabilite) and the pentahydrate form favors the precipitation of the anhydrous sodium sulfate crystals (thenardite) with an altered crystal habit. Using X-ray diffraction, overdevelopment of the (111), (131), (222) and (153) faces of thenardite was identified. Additionally, the ratios between several peaks are reversed. These results confirm the deviation of the grown crystals of the equilibrium crystal shape of thenardite as observed with optical microscopy., Accepted Author Manuscript, Heritage & Technology

Borax has been identified as a possible crystallization modifier for sodium sulfate. Understanding the effect of borax on factors influencing transport and crystallization kinetics of sodium sulfate helps to clarify how this modifier might limit crystallization damage. It has been observed that the addition of borax to sodium sulfate solutions has no influence on the wetting properties (contact angle on glass, surface tension, or evaporation rate) and therefore will not influence solution transport. Additionally, the influence of borax on the crystallization kinetics of sodium sulfate was studied under controlled environmental conditions. This was carried out in mixtures in glass microcapillaries, and sequentially in droplets on glass plates. Under the here studied precipitation conditions, the addition of borax has no influence on the supersaturation ratio at the onset of crystallization, but it significantly affects the crystallization pattern of anhydrous sodium sulfate crystals (thenardite). Using RAMAN spectroscopy, two different hydrates of borax were identified after precipitation, depending on the initial concentration of the solution. Each hydrate has a different effect on the subsequent crystallization of sodium sulfate. The decahydrate polymorph of borax leads to the precipitation of hydrated sodium sulfate crystals (mirabilite) and the pentahydrate form favors the precipitation of the anhydrous sodium sulfate crystals (thenardite) with an altered crystal habit. Using X-ray diffraction, overdevelopment of the (111), (131), (222) and (153) faces of thenardite was identified. Additionally, the ratios between several peaks are reversed. These results confirm the deviation of the grown crystals of the equilibrium crystal shape of thenardite as observed with optical microscopy., Accepted Author Manuscript, Heritage & Technology

Built heritage contains value on many scales. On the most basic level it represents the investment of building materials following a constructional logic. As the use of once-predominant materials goes out of fashion due to changing technological regimes and architectural styles, knowledge about them is lost. Yet retaining and maintaining their embodied energies in place is an important aspect of resource efficiency. Waste management, circularity and in situ retention of built fabric as useful resource is a sustainability ambition for built environment systems in general and for heritage conservation in particular. The Netherlands and South Africa have a long historic association. Therefore commonality is to be found in the constructional logic of the shared built heritage of both countries. This historic association brought the transfer of construction components through material streams as well as the transfer of knowledge from the Netherlands to climatically different South Africa. It is expected that the historic transfer of knowledge and materials from the Netherlands to South Africa has led to climate adaptive and practical alterations of Dutch principles. These hold potential to shed valuable new light on retaining built fabric in the Netherlands average temperatures are increasing. Dutch knowledge on maintenance and repair can augment the rather scant South African body of knowledge on material maintenance and repair. This paper will explore the possibilities for collaborative research on material maintenance and repair from the perspective of Smart and Sustainable Cities, identifying opportunities for collaboration in the commonalities that exists between the Netherlands and South Africa., Heritage & Technology, Teachers of Practice

This paper presents the most important results of a research project which focused on the use of crystallization modifiers mixed in lime mortar to mitigate salt crystallization damage. The research focused on two of the most damaging salts, sodium chloride and sodium sulfate, and suitable crystallization modifiers (sodium ferrocyanide and borax). We report the major findings related to the effectiveness of the modifiers when mixed in the mortar, and the results of characterization of the additivated mortars in comparison with reference mortars. Moreover, the durability of the developed mortars to salt decay is discussed, based on the results of an accelerated salt weathering test carried out in laboratory. No major effects of the modifiers on the fresh and hardened mortar properties were observed which might restrain the application of crystallization modifiers in restoration mortars. Additionally, the mortars with mixed-in modifiers showed a considerable improvement of the salt resistance when compared to reference mortars. Considering these results an outlook for future research pathways is given., This paper was previously presented at and published in the Proceedings of the 4th WTA International PhD Symposium, 13-16 September, Delft, The Netherlands. The paper was reproduced for the SWBSS conference with permission of the organizing committee., Heritage & Technology

This paper describes some of the most important results of a four year PhD research on the use of crystallization modifiers mixed in lime mortar to mitigate salt crystallization damage. The research focused on two of the most damaging salts, sodium chloride and sodium sulfate, and suitable crystallization modifiers (sodium ferrocyanide and borax). We report the major findings related to the effectiveness of the modifiers when mixed in the mortar, and the results of characterization of the additivated mortars in comparison with reference mortars. Moreover, the durability of the developed mortars to salt decay is discussed, based on the results of an accelerated salt weathering test carried out in laboratory. No major effects of the modifiers on the fresh and hardened mortar properties were observed which might restrain the application of crystallization modifiers in restoration mortars. Additionally, the mortars with mixed-in modifiers showed a considerable improvement of the salt resistance when compared to reference mortars. Considering these results an outlook for future research pathways is given., Heritage & Technology

Borax has been identified as a possible crystallization modifier for sodium sulfate. Understanding the effect of borax on factors influencing transport and crystallization kinetics of sodium sulfate helps to clarify how this modifier might limit crystallization damage. It has been observed that the addition of borax to sodium sulfate solutions has no influence on the wetting properties (contact angle on glass, surface tension, or evaporation rate) and therefore will not influence solution transport. Additionally, the influence of borax on the crystallization kinetics of sodium sulfate was studied under controlled environmental conditions. This was carried out in mixtures in glass microcapillaries, and sequentially in droplets on glass plates. Under the here studied precipitation conditions, the addition of borax has no influence on the supersaturation ratio at the onset of crystallization, but it significantly affects the crystallization pattern of anhydrous sodium sulfate crystals (thenardite). Using RAMAN spectroscopy, two different hydrates of borax were identified after precipitation, depending on the initial concentration of the solution. Each hydrate has a different effect on the subsequent crystallization of sodium sulfate. The decahydrate polymorph of borax leads to the precipitation of hydrated sodium sulfate crystals (mirabilite) and the pentahydrate form favors the precipitation of the anhydrous sodium sulfate crystals (thenardite) with an altered crystal habit. Using X-ray diffraction, overdevelopment of the (111), (131), (222) and (153) faces of thenardite was identified. Additionally, the ratios between several peaks are reversed. These results confirm the deviation of the grown crystals of the equilibrium crystal shape of thenardite as observed with optical microscopy., Accepted Author Manuscript, Heritage & Technology

Built heritage contains value on many scales. On the most basic level it represents the investment of building materials following a constructional logic. As the use of once-predominant materials goes out of fashion due to changing technological regimes and architectural styles, knowledge about them is lost. Yet retaining and maintaining their embodied energies in place is an important aspect of resource efficiency. Waste management, circularity and in situ retention of built fabric as useful resource is a sustainability ambition for built environment systems in general and for heritage conservation in particular. The Netherlands and South Africa have a long historic association. Therefore commonality is to be found in the constructional logic of the shared built heritage of both countries. This historic association brought the transfer of construction components through material streams as well as the transfer of knowledge from the Netherlands to climatically different South Africa. It is expected that the historic transfer of knowledge and materials from the Netherlands to South Africa has led to climate adaptive and practical alterations of Dutch principles. These hold potential to shed valuable new light on retaining built fabric in the Netherlands average temperatures are increasing. Dutch knowledge on maintenance and repair can augment the rather scant South African body of knowledge on material maintenance and repair. This paper will explore the possibilities for collaborative research on material maintenance and repair from the perspective of Smart and Sustainable Cities, identifying opportunities for collaboration in the commonalities that exists between the Netherlands and South Africa., Heritage & Technology, Teachers of Practice

This paper describes some of the most important results of a four year PhD research on the use of crystallization modifiers mixed in lime mortar to mitigate salt crystallization damage. The research focused on two of the most damaging salts, sodium chloride and sodium sulfate, and suitable crystallization modifiers (sodium ferrocyanide and borax). We report the major findings related to the effectiveness of the modifiers when mixed in the mortar, and the results of characterization of the additivated mortars in comparison with reference mortars. Moreover, the durability of the developed mortars to salt decay is discussed, based on the results of an accelerated salt weathering test carried out in laboratory. No major effects of the modifiers on the fresh and hardened mortar properties were observed which might restrain the application of crystallization modifiers in restoration mortars. Additionally, the mortars with mixed-in modifiers showed a considerable improvement of the salt resistance when compared to reference mortars. Considering these results an outlook for future research pathways is given., Heritage & Technology

This paper presents the most important results of a research project which focused on the use of crystallization modifiers mixed in lime mortar to mitigate salt crystallization damage. The research focused on two of the most damaging salts, sodium chloride and sodium sulfate, and suitable crystallization modifiers (sodium ferrocyanide and borax). We report the major findings related to the effectiveness of the modifiers when mixed in the mortar, and the results of characterization of the additivated mortars in comparison with reference mortars. Moreover, the durability of the developed mortars to salt decay is discussed, based on the results of an accelerated salt weathering test carried out in laboratory. No major effects of the modifiers on the fresh and hardened mortar properties were observed which might restrain the application of crystallization modifiers in restoration mortars. Additionally, the mortars with mixed-in modifiers showed a considerable improvement of the salt resistance when compared to reference mortars. Considering these results an outlook for future research pathways is given., This paper was previously presented at and published in the Proceedings of the 4th WTA International PhD Symposium, 13-16 September, Delft, The Netherlands. The paper was reproduced for the SWBSS conference with permission of the organizing committee., Heritage & Technology

Rising damp is a recurrent hazard to ancient buildings and its relevance is expected to increase in future, due to climate changes. In spite of the large diffusion of methods and products to stop rising damp, scientific literature on their effectiveness in the field is often scarce and not conclusive. This is particularly true for recent solutions; examples are the “electro-physical” methods, which are currently flourishing in many countries. These methods are often lacking a scientifically based proof of their working principles and effectiveness. Within the JPI-CH project EMERISDA, the effectiveness of two different commercial electro-physical devices was investigated in two case-studies. The devices were positioned in such a way as to include humid walls under the influence of the device as well as humid walls, comparable in orientation and structure, out of its reach, to be used as reference. The effectiveness of the devices was assessed by collection of samples at different heights and depths in the walls and gravimetric determination of their moisture content. Conclusions are drawn on the effectiveness of the methods by comparing the moisture content before and one year after the intervention, taking into account the variation in moisture content in the reference walls., Heritage & Technology

The paper addresses the consolidation of plasters and renders showing loss of cohesion, with the use of a treatment with a liquid consolidating product aiming to reach a depth of several mm up to several cm. The main aim of the paper is offering a guideline on how to choose a consolidant, suitable and compatible for the mortar type and its condition, and how to assess the performance of a consolidation treatment., Accepted Author Manuscript, Heritage & Technology

Occasionally, a profound but distant connection between volcano and culture exists. This is the case between the volcanic Eifel region in Germany and historic construction in the Netherlands, with the river Rhine as physical and enabling connection. Volcanic tuff from the Eifel comprises a significant amount of the building mass in Dutch built heritage. Tuffs from the Laacher See volcano have been imported and used during Roman occupation (hence called Römer tuff). It was the dominant dimension stone when construction in stone revived from the 10th century onwards, becoming the visual mark of Romanesque architecture in the Netherlands. Römer tuff gradually disappeared from the market from the 12th century onwards. Early 15th century, Weiberner tuff from the Riedener caldera, was introduced for fine sculptures and cladding; it disappears from use in about a century. Late 19th century, this tuff is reintroduced, both for restoration and for new buildings. In this period, Ettringer tuff, also from the Riedener caldera, is introduced for the first time. Ground Römer tuff (Rhenish trass) was used as a pozzolanic addition to lime mortars, enabling the hydraulic engineering works in masonry that facilitated life and economics in the Dutch delta for centuries., Heritage & Technology

Heritage & Technology

The application of structural glass as the principal material in restoration and conservation practices is a distinguishable, yet discreet approach. The transparency of glass allows the simultaneous perception of the monument at both its original and present condition, preserving its historical and aesthetical integrity. Concurrently, the material’s unique mechanical properties enable the structural consolidation of the monument. As a proof of concept, the restoration of Lichtenberg Castle is proposed. Solid cast glass units are suggested to complete the missing parts, in respect to the existing construction technique and aesthetics of the original masonry. Aiming for a reversible system, the glass units are interlocking, ensuring the overall stability without necessitating permanent, adhesive connections. This results in an elegant and reversible intervention., Structural Design & Mechanics, Applied Mechanics, Heritage & Technology

The potentialities of nanomaterials for applica- tion in the field of conservation have been widely investi- gated in the last two decades. Among nanomaterials, nanolimes, i.e., dispersions of lime nanoparticles in alco- hols are promising consolidating products for calcareous materials. Nanolimes are effective in recovering the very superficial loss of cohesion of decayed materials, but they do not always provide sufficient mass consolidation. This limitation is mainly related to the deposition of the nanoparticles nearby the surface of the material. Experi- mental research has been set up with the aim of improving the in-depth deposition of lime nanoparticles. Previous research by the authors has shown that nanolime deposition within a substrate can be controlled by adapting the nanolimes properties (kinetic stability and evaporation rate) to the moisture transport behavior of the substrate. Nanolime properties can be modified by the use of different solvents. In this research, nanolime dispersions have been further optimized for application on Maastricht limestone, a coarse porous limestone. Firstly, nanolimes were syn- thesized and dispersed in ethanol and/or water, both pure and mixed in different percentages. Subsequently, based on the kinetic stability of the nanolime dispersions, the most promising solvent mixtures were selected and applied on the limestone. The deposition of lime nanoparticles within the limestone was studied by phenolphthalein test, optical microscopy and scanning electron microscopy. The results confirm that nanolime dispersed in a mixture of ethanol (95 %) and water (5 %) can guarantee a better nanoparti- cles in-depth deposition within coarse porous substrates, when compared to dispersions in pure ethanol., Heritage & Technology

Steenreparatiemortels worden gebruikt voor het aanvullen van een ontbrekend deel van het originele materiaal. Dat laatste kan verloren zijn gegaan door een mechanische belasting of door bijvoorbeeld aantastingsprocessen waarbij vocht, vorst en of zouten een rol spelen. Het ontbrekende deel wordt dan aangevuld met een mortel met een passende kleur en textuur. De gebruikte mortel is als het ware ‘kneedbaar’, zodat aanpassing aan de gewenste vorm eenvoudig mogelijk is. Gewoonlijk gaat het om kleinschalige ingrepen, waarbij individuele stenen, details en delen van ornamenten of beelden worden behandeld. In de kleinschaligheid, de individuele benadering en de ‘boetseerbaarheid’ liggen de voornaamste verschillen met andere ingrepen waarbij mortel wordt toegepast, zoals hervoegwerk, vervangen van pleisterwerk en dergelijke., Heritage & Technology

AE+T, Architecture and The Built Environment