Variation of microstructure with carbonation in lime and blended pastes

Carbonation, as a reaction of the curing process of both, cement and lime binders, modifies the microstructure. Several microstructure properties, namely, porosity, pore size distribution, surface fractal dimension and specific surface area have been investigated in this study to describe the effect of carbonation on microstructure. Both carbonated and non-carbonated pastes of lime and blended pastes of lime and cement having varying W/B (water/binder) ratios are studied. Results show that carbonation decreases the porosity, but not with the same intensity in all pore size ranges. The highest modification is between 0.03 and 0.01 µm in lime pastes and between 0.2 and 0.02 µm in 50% lime pastes, while in 80% lime pastes the modification is very small. It is also observed that carbonation is a function of the binder composition but not of the W/B ratio. Moreover, surface fractal dimension decreases during the carbonation process, while the specific surface area varies depending of the binder composition

RILEM TC 243-SGM report

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.Zgodovinski konstrukcijski in nekonstrukcijski elementi so običajno nosilci za plasti malte (zunanji in notranji ometi, estrihi), zaradi njihove zaščite in kot podlaga za dekorativne sloje. Te dobro obdelane arhitekturne stratigrafske površine so pogosto podvržene propadanju, kot je pomanjkanje oprijema ali ločitev med podpornimi in maltnimi plastmi ter celo med maltnimi plastmi. Injektiranje in zapolnjevanje žepov med razslojenimi plastmi je lahko učinkovit poseg, če so plasti kompaktne. Prispevek obravnava vidike, ki so pomembni za izbiro, projektiranje in uporabo injekcijske mase za in situ stabilizacijo in ohranitev zgodovinskih arhitekturnih površin. Predstavlja metodološki pristop, v skladu s konservatorskimi načeli, vključno z diagnostiko za oceno obsega poškodovanosti, opredelitvijo zahtev za injekcijske mase, izbiro ustreznih sestavin injekcijske mase, bodisi izdelane po meri ali komercialne, ter pripravo in poskusnim testiranjem me šanic in njihove aplikacije na terenu. Članek, ki je pripravljen v okviru RILEM TC 243 SGM, je lahko vodilo uporabnikom injekcijskih mas na osnovi apna pri sanaciji in obnovi zgodovinskih arhitekturnih površin, ki temelji na najnovejših znanstvenih in strokovnih spoznanjih

RILEM TC 243-SGM report: grouting for historic architectural surfaces

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 MechanicsHeritage & Technolog

RILEM TC 277-LHS report

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 plastershowever, 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 mortarsproperties related to the hygric behaviourand 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 mould

RILEM TC 277-LHS report: properties of lime-based renders and plasters—discussion of current test methods and proposals for improvement

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 modifications on curing conditions and times of mixing and testing. Additionally, test methods developed at laboratory to evaluate the cracking tendency due to restrained shrinkage and to determine the modulus of elasticity of under checking mortars are proposed, as well as alternative test methods for adhesion. In the case of testing other properties, smaller changes are proposed, in order for the standardized test methods to be adapted to the particularities of lime-based renders and plasters. As conclusions, in the third section, a synthesis of the proposed changes and complementary tests has been made in formulated tables, that could be considered as a first approach of adapted requirements for better performance of lime-based mortars for renders and plasters.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 & Architectur

Repair Mortars for Historic Masonry - State of the Art Report of RILEM Technical Committee TC 203-RHM

The authors of this report are the members of RILEM technical committee 203-RHM Repair Mortars for Historic Masonry which was created in September 2003 as a successor to RILEM technical committee 167-COM Characterisation of old mortars with respect to their repair. The aim of both committees was to develop methods and recommendations to improve the quality of restoration practices in the field of repair mortars for older (historic) masonry. An important reason for forming the committees was to give guidance on appropriate mortars and practices to avoid the many mistakes which had been occurring in practice in choosing repair mortars for existing masonry, thereby greatly increasing the risk of damage. Badly needed were recommendations based on the phenomena which play a role in regard to the compatibility of mortar and brick and aspects such as long-term quality and durability of masonry. The target group for this publication include architects, engineers, contractors and researchers. Committee 167-COM laid the foundation for the work by analyzing problems encountered in the field and describing test methods to determine relevant characteristics of historic mortars and substrates. In addition a general overview of the requirements playing a role with regard to repair was formulated. Committee 203-RHM focussed specifically on repair. The subject matter was formulated as follows: - Classification of types of historic masonry, types of repair problems and functional uses for repair mortars. - Development of technical performance requirements and design guidelines for compatible and durable repair mortars. - Only repair mortars with binders derived from limestone were considered. Examples of such binders are air lime, hydraulic lime and Portland cement. During discussions the committee soon arrived at the conclusion that the performance requirements for mortars may vary significantly as a function of the type of repair. Consequently, in this report the most important applications of repair mortars are treated in separate chapters: pointing, bedding, renders/plasters and flooring mortars. These chapters are preceded by a chapter on the role of mortar in historic masonry, a chapter addressing the decision process taking place between the analysis of the problem and the repair intervention, and a chapter on general performance requirements for mortars. The last chapter describes test methods for mortar which can be used for quality control and to assess performance requirements. During its existence from 2003 to 2010 the committee met twelve times. In addition it organised a workshop held in Delft, the Netherlands, in 2005 (see Rilem proceedings pro67). In 2010 summary papers of the committee’s work were presented during a workshop in Prague, organised in conjunction with the 2nd Historic Mortars Conference in Prague, Czech Republic (see Rilem proceedings pro78). The committee’s activities were carried out by an interdisciplinary group which included chemists, civil engineers, mineralogists, geologists, architects and building engineers. Unless otherwise noted, the photos were provided by the TC members and their organisations