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Lime-based mortars (LM(s)) seem to be preferred in repairing historic structures. The long-term performance of repair LM(s) is closely related to durability issues concerning the old structure substrate, the new repair mortars and interface between the two aforementioned materials, which is also much influenced by the technique of mortars application. Durability is a multifunctional property affected by a number of parameters, including local environmental conditions. However, experience showed that some of the characteristics of materials play a dominant role in assessing the durability of repair LM(s) and have a direct impact on longevity of the repaired structure. This paper presents review of research/case studies papers and Master/PhD theses supervised by the members of RILEM TC 277 LHS. Through the review and evaluation of research and common practice concerning durability challenges, we anticipate to find answers to questions arising in assessing durability of repair LM(s), such as: The most often encountered failures due to mortar durability inadequacy The mortar properties/characteristics that seem to be influential on durability The test methods used for testing the durability of LM(s) and comments related to their applicability and performance The importance of quality control and on site execution practices

The potentialities of nanomaterials for application in the field of conservation have been widely investigated in the last two decades. Among nanomaterials, nanolimes, i.e., dispersions of lime nanoparticles in alcohols 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. Experimental 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 synthesized 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 nanoparticles in-depth deposition within coarse porous substrates, when compared to dispersions in pure ethanol. 10p The authors acknowledge Delft University of Technology and TNO (The Netherlands) for the financial support. Special thanks go to Timo Nijland, Willem Duvalois (TNO, The Netherlands) for SEM–EDS analysis. Applied Physics A - Materials Science & Processing, DM/NMM

This article focuses on repair or replacement mortars for historical buildings. Both the decision process and questions arising are dealt with, in order to better define and illustrate technical requirements for mortars to be used for the repair or restoration of monuments and historic buildings (masonry mortars, plasters, renders…). The article summarizes a longer document, meant to help professionals in their decisions on the interventions, taking into account aspects, which are ranging from the ethics of restoration to the technical requirements.

An important part of the Built Heritage is made of calcareous stone and lime-based plasters and renders. When exposed to weathering, these materials may suffer from several degradation processes. Decay patterns, as powdering and/or sanding, can arise and induce a loss of cohesion. Consolidation treatment is a common practice to restore degraded historical materials. Nevertheless, when considering calcareous materials, there is a lack of efficient and compatible consolidants. Nanolimes, i.e. colloidal dispersions of calciumhydroxide, intend to overcome the limitations of traditional consolidants and have demonstrated to properly recover the superficial decohesion. However, nanolimes do not always guarantee a in depth consolidation, necessary e.g. in the case of decayed stone or render. In fact, the high kinetical stability and volatility of the nanolimes inhibit the phase separation of the lime nanoparticles from the alcoholic solvent. A modification of the solvent appears a promising strategy to enhance nanolime deposition in depth. The aim of this research is to study the behaviour of new nanolimes, dispersed in ethanol, isopropanol, butanol or water. The nanosize and morphology of the nanolimes were assessed by SEM-EDS and DLS, and the kinetical stability studied by Uv-Vis spectroscopy; the absorption and drying kinetics of the new nanolimes, applied on Maastricht limestone and lime-based mortars, was measured. The SEM-EDS observations and the DLS analyses show that lime nanoparticles have rounded to hexagonal shape and nano to submicrometric size (70 to 500nm). Compared to nanolime dispersed in ethanol, the new nanolimes in butanol and water have lower kinetical stability and faster drying rate. This is expected to favour the precipitation of nanoparticles in depth.

This paper gives a summary of functional and performance requirements for repointing mortars for historic masonry (design, execution and maintenance). Successful performance of repair and conservation of mortar in historic masonry requires more care with design and execution than with modern masonry. © 2012 RILEM.

Mortar has been in use for many thousands of years and is integral to most masonry construction. Its use is widespread in every culture where masonry is constructed. It is present in the majority of the global built cultural heritage, and is therefore a major consideration in building conservation. The effective design of a mortar for repairing masonry depends on a clear understanding of its function. The main functional uses of mortar in masonry are classified as bedding, pointing, grout, render, plaster, flooring and mortars for surface repairs. The requirements that each type of mortar must meet in service depend on its environmental exposure and its role in the masonry element that it is found within (e.g. issues such as historic authenticity, aesthetics, resistance to moisture ingress, structural integrity, and service life). Technical requirements such as adhesion, strength, elasticity, water and vapour transmittance, drying behaviour, thermal dilatation, ability to deal with salt contamination and freeze–thaw cycling, and its aesthetic properties can be quantified. Mortar properties can be adjusted by varying ingredients and their proportions, to meet the differing technical requirements

This paper presents an approach to the use and interpretation of tests on mortar samples when restoring historic masonry. It is largely based on the work performed by the former RILEM technical committee 167-COM, Characterisation of old mortars, closed in 2003, and the ongoing committee 203-RHM, Repair mortars for historic masonry. The focus of the present paper is on the decision process: what to test and how to interpret the test results.

By means of a questionnaire a study was carried out to investigate the perception of small scale damage and repairs of natural stone used in buildings. Participants were asked to evaluate damage to natural stone shown on pictures. They were also asked to give their opinion on interventions needed to preserve or restore the material. Significant differences can be found between specialists and non-specialists in conservation. Respondents consider some cases as “damage” situations, even though no intervention is deemed as necessary, as if damage was a sort of natural weathering, thus to be expected and accepted. In other cases, also defined as “‘damage” situations, interventions are considered necessary. This seems to imply the use of a different criterion to define “damage”, maybe including the expected risks related to its development. This study contributes to the definition of damage, and to a better understanding of the criteria used by different people to decide on the need of interventions.

The atmospheric and geospatial communities are still separate worlds with their own tools and data formats. It is extremely difficult to easily share data among scientists representing these communities without performing some cumbersome conversions. ADAGUC aims to reduce the need for scientists to invent their own converter tools. Selected space borne atmospheric datasets will be made accessible to a GIS system in order to be submitted to data comparison, resampling, selection, manipulation and visualization. The user community will be intensively involved in the project to obtain a high fitness for use. The first ADAGUC workshop (Oct 2006) was attended by a large group of users from both the atmospheric and GIS community and resulted in a better understanding of user needs that are currently translated into specifications for the user requirements document of ADAGUC. The deliverables of this project are: Open Source conversion tools, selected atmospheric datasets in a GIS-friendly format and a web service to demonstrate the usability of the above to the geospatial and atmospheric community.

Changes in the air RH can cause damage to building materials contaminated with hygroscopic salts, even in the absence of any other moisture source. This phenomenon has been observed in the case of the Waag building in Amsterdam, affected by severe salt decay. The investigation, carried out by means of different techniques (e.g. ESEM-EDX, IC and XRD), has revealed the presence in the masonry of a large amount of hygroscopic salts (mainly sodium chloride and nitrates) and the absence of any moisture sources other than the RH of the air. Besides, an adsorption experiment performed on samples from the building has pointed out the hygroscopic moisture uptake of the salt mix even at low RH. These results, in combination with a monitoring of the interior climate for a period of about 1 year, have allowed to conclude that the damage observed is due to the frequent RH changes through the equilibrium where dissolution/crystallization of the salt mix takes place. On the basis of these findings an advice for the conservation of the building was given. In: Bauinstandsetzen und Baudenkmalpflege Vol. 13, No. 4, 241–250 (2007)