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The Alcazaba of Almería (Spain) is one of the most important Arabic fortresses of the Iberian Peninsula archaeological record. It is located in the south of Spain, on the Mediterranean coast, and its construction dates back to the late 10th century. It consists of three enclosures, two of which belong to the Andalusian period, while the last one dates from the 16th century. However, very few materials’ studies have been performed in this complex, despite the incomparable historic relevance. In this study, we present an extensive mineralogical and physical-chemical characterization of the construction materials of this site, divided in mortars, earthen materials and bricks. We provide an unprecedent scientifical-technical study of the building materials of this fortress, so as to understand the building techniques used and the causes of deterioration. All collected samples were analyzed by means of X-ray diffraction, scanning electron microscopy, optical microscopy thermogravimetric analysis and stereo-zoom microscopy. Our results reveal that main phases used for construction materials on this site were Ca and Mg-carbonates, accompanied by Fe-Ca-Mg silicates. Mortars showed a carbonate-binder composition with non-hydraulic nature whereas calcination of raw materials occurred below 800 ºC due to the permanence of dolomite. Furthermore, we demonstrated that the construction materials from the Alcazaba suffered such relevant damages due to the precipitation of salts (i.e., gypsum and halite) caused by coastal environment, key information for future archaeological restoration work in this highly significant location. We show that, in mortars and earthen materials, halite nucleates in fractures and dissolution pits exerting a crystallization pressure ∼ 100 MPa to cause fracture. Furthermore, calcium and magnesium silicate hydrates were observed confirming some pozzolanic properties. Finally, the bricks studied here demonstrated that firing T maximum of 700 ºC due to the presence of carbonates. This work opens new pathways to develop specific consolidation methods of materials and structural elements, as well as to ensure adequate restoration and conservation, of similar archaeological sites in coastal-related environments

A favorable environment for fungi colonization in building materials' surfaces can emerge when certain hygrothermal conditions occur. Thus, reducing fungal growth susceptibility is of major interest. Furthermore, if the integration of bio-wastes is performed in parallel with the development of innovative materials for this purpose, a more sustainable and environmentally friendly material can be obtained. In this study, the fungal susceptibility of lime mortars incorporating almond-shell powder (ASP) microparticles (2 and 4%, wt.–wt. in relation to the binder content) was evaluated. The particle-dispersion technique was employed to prepare the bio-waste introduced in the mixtures. The fungal susceptibility of ASP samples was compared with nanotitania (n-TiO2) with recognized antifungal properties. Mechanical strength, water absorption, and wettability tests were also performed for a better characterization of the composites. Although the addition of 2% ASP led to mechanical properties reduction, an increase in the compressive and flexural strength resulted for 4% of the ASP content. Difficulties in fungal growth were observed for the samples incorporating ASP. No fungal development was detected in the mortar with 2% of ASP, which may be correlated with an increase in the surface hydrophobic behavior. Furthermore, mortars with ASP revealed a reduction in water absorption by capillarity ability, especially with 4% content, suggesting changes in the microstructure and pore characteristics. The results also demonstrated that an improvement in the physical and mechanical properties of the lime mortars can be achieved when ASP microparticles are previously subjected to dispersion techniques. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Graduate School of Natural & Applied Sciences of Mehmet Akif Ersoy University / Mehmet Akif Ersoy Üniversitesi Fen Bilimleri Enstitüsü Dergisi is the property of Burdur Mehmet Akif Ersoy University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Slaked lime is traditionally a suitable material for use in construction activities in historic and traditional buildings whose constitutive characteristics demand compatible and appropriate material solutions. Therefore, knowing the physical and mechanical characterization of lime pastes and mortars for use in restoration is considered an important step in the process of scientific development of a material that, in the Mexican case, has lacked scientific rigor in its production, use and commercialization. With this in mind, the present article aims to investigate the characteristics of lime pastes and mortars that have been used in the traditional way and the new limes that exist in the market, offering suitable options for restoration, for which an integrated methodology was used consisting of physical tests such as surface area, electrical resistivity, pulse velocity, colorimetry, and mechanical tests such as compressive strength, giving as a result that “traditional slaked” lime is more likely to deteriorate than powdered lime, which leads us to conclude that powdered hydrated lime has optimal characteristics for restoration activities.

A favorable environment for fungi colonization in building materials’ surfaces can emerge when certain hygrothermal conditions occur. Thus, reducing fungal growth susceptibility is of major interest. Furthermore, if the integration of bio-wastes is performed in parallel with the development of innovative materials for this purpose, a more sustainable and environmentally friendly material can be obtained. In this study, the fungal susceptibility of lime mortars incorporating almond-shell powder (ASP) microparticles (2 and 4%, wt.–wt. in relation to the binder content) was evaluated. The particle-dispersion technique was employed to prepare the bio-waste introduced in the mixtures. The fungal susceptibility of ASP samples was compared with nanotitania (n-TiO2) with recognized antifungal properties. Mechanical strength, water absorption, and wettability tests were also performed for a better characterization of the composites. Although the addition of 2% ASP led to mechanical properties reduction, an increase in the compressive and flexural strength resulted for 4% of the ASP content. Difficulties in fungal growth were observed for the samples incorporating ASP. No fungal development was detected in the mortar with 2% of ASP, which may be correlated with an increase in the surface hydrophobic behavior. Furthermore, mortars with ASP revealed a reduction in water absorption by capillarity ability, especially with 4% content, suggesting changes in the microstructure and pore characteristics. The results also demonstrated that an improvement in the physical and mechanical properties of the lime mortars can be achieved when ASP microparticles are previously subjected to dispersion techniques.

The scope of this collective paper produced in the frame of RILEM TC 277-LHS is to provide sound knowledge on the use of additives/admixtures in lime-based mortars, based on literature and practice. The most widely known additives/admixtures are systematically presented. Their main effects and testing of their performance have been properly tabulated. It is well known that a plethora of additives/admixtures are produced every year by chemical industries. However, when using them in lime-based mortars, compatibility and durability aspects are of primary importance. The introduction of additives/admixtures in lime mortars was imposed by the need to improve important properties of these composites in the fresh and hardened state, namely, workability, durability, early-age and long-term strength and to reduce defects, such as shrinkage and long setting time. In this review paper, the terminology proposed by EN 16572 is followed, designating additive as a constituent added in small quantity to the binder, and admixture as a substance in quantities at least 1% w/w added to the mix. The additives/admixtures are classified according to their action and their validation with specific testing methodologies highlights the dosage sensitivity and the need to develop further standardization. The combination of different additives proposed in several studies resulted as the most promising strategy to enhance the performance of lime mortars. However, recently developed additives and admixtures need to be further evaluated with reference to their compatibility with other mortar constituents, and their effects on the overall mortar and render durability need to be studied. Finally, adopting similar terminology for additives/admixtures in lime and cement-based mortars will facilitate better comparison and assessment issues. [ABSTRACT FROM AUTHOR]

Slaked lime is traditionally a suitable material for use in construction activities in historic and traditional buildings whose constitutive characteristics demand compatible and appropriate material solutions. Therefore, knowing the physical and mechanical characterization of lime pastes and mortars for use in restoration is considered an important step in the process of scientific development of a material that, in the Mexican case, has lacked scientific rigor in its production, use and commercialization. With this in mind, the present article aims to investigate the characteristics of lime pastes and mortars that have been used in the traditional way and the new limes that exist in the market, offering suitable options for restoration, for which an integrated methodology was used consisting of physical tests such as surface area, electrical resistivity, pulse velocity, colorimetry, and mechanical tests such as compressive strength, giving as a result that "traditional slaked" lime is more likely to deteriorate than powdered lime, which leads us to conclude that powdered hydrated lime has optimal characteristics for restoration activities. [ABSTRACT FROM AUTHOR]

This study examines the mortar materials used in the construction of the walls at the Archaeological Roman Fortification site (Ovidiu, Romania) on the shore of Siutghiol Lake. Several analyses were conducted to determine the mortars' basic physical properties, mineralogical composition, and microstructural characteristics in order to describe the mortars used in the construction of the Roman fortress. The investigation utilized X-ray diffraction (XRD), energy dispersive X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM-EDAX), and differential thermal analysis (TGA-DTA). The results indicated that siliceous aggregates and lime binders were used in the production of the studied mortars, the structure was constructed in the sixth century, and the raw materials used to construct the site are of local origin. Using the methods mentioned above, there is the possibility of recreating the fortification's mortar formula using contemporary materials and recommending intervention materials for the preservation of the archaeology of the Roman Fortification. Furthermore, this study opens up many other research opportunities regarding the reuse of mortars extracted from archaeological sites in the rehabilitation process by integrating them into new mortar recipes that can then be tested to compare the results with those obtained from standardized recipes. [ABSTRACT FROM AUTHOR]

In every restoration project, knowledge of the mechanical properties of the original materials is considered essential for engineers, not only for the structural assessment of the monument, but also for the selection of compatible restoration materials. In the case of mortars, however, direct or indirect determination of their mechanical properties is usually challenging, due to the limited size and number of available samples. Hence, alternative non- or micro-destructive techniques need to be exploited for the evaluation of the compressive and flexural strength of historic mortars. In this study, the micro-destructive scratching resistance test is used to assess the compressive and flexural strength of a variety of lime-based mortars, that were either designed and produced in the laboratory using different binders, aggregates and admixtures, or sampled in-situ. Sound linear correlations observed between the intrinsic specific energy, resulting from the scratching resistance test, and the compressive and flexural strength of the laboratory designed and produced mortars validate the potential of the scratch tool in assessing the aforementioned mechanical properties of lime-based mortars. This is further confirmed by results on historic mortar fragments. Therefore, the use of the novel micro-destructive scratch tool is recommended in cases where lime mortar sampling is limited, in order to provide reliable estimates for the mechanical properties of historic mortars. [ABSTRACT FROM AUTHOR]

Abstract The most obvious characteristics of the Ming Great Wall are external masonry walls made of natural stones, bricks and lime mortars. According to the chemical and mineralogical compositions of the original bedding and pointing mortars, dolomitic lime binder was used dominantly in the construction of the Ming Great Wall in provinces such as those around Beijing and Hebei. Calcium-rich lime and air lime with low natural hydraulically reactive phases, which are hydrated and react slowly with the carbon dioxide in air to form calcium carbonate, were used in some western provinces. Chemical and microscopic investigations show that both dolomitic and calcium-rich lime mortars are almost aggregate-free. Historic dolomitic lime mortars are characterised by high strengths, low porosities and dense micro-scale textures. The most recent conservation principle is to preserve the Ming Great Wall as a ruin. Therefore, the conservation strategy should be redefined in terms of mortars. Since some of the damage to the Great Wall is related to reactions between dolomitic lime mortars and air pollutants, calcium-rich lime binders should be used for conservation and even for restoration of those parts of the Great Wall that were originally built with dolomitic lime. Binders based on natural hydraulic lime and calcium-rich lime gauged with natural pozzolana might be more compatible than other binders” for the structural consolidation of the ruins of the Great Wall.

The present study focuses on the evaluation of the physical-mechanical characteristics of restoration mortars, designed for the conservation works of the Acropolis monuments in Athens, Greece. The mortars were prepared with different mixing ratios of hydrated lime/metakaolin, natural hydraulic lime/metakaolin, hydrated lime/cement and cement/natural pozzolan, using aggregates of different nature and grain size distribution. The mortars were evaluated till 24 months of curing. The mechanical characteristics were studied through mechanical strength tests in different curing times to determine the flexural and compressive strength and through ultrasonic pulse velocity measurements to determine the dynamic modulus of elasticity. The physical and moisture transfer properties were estimated through laboratory methods (apparent density, porosity accessible to water, total water absorption and water absorption coefficient by capillary). In addition, the durability of the mortars was tested through accelerated ageing tests in salt cycles. The results of the study showed that the hydrated lime/cement mixtures did not meet the desired criteria and therefore are not considered appropriate for application. On the contrary, the addition of metakaolin to hydrated lime mortars in certain quantities led to improved mechanical properties, while providing satisfactory hygrometric properties and sufficient resistance to the action of soluble salts, rendering these mix designs suitable for use in conservation interventions on the Acropolis monuments. [ABSTRACT FROM AUTHOR]

• Usage of nanosilica in restoration mortars without dispersing or water reducing additives was investigated. • Formation of metastable polymorphs of CaCO 3 was observed using SEM and their amount was quantified with XRPD. • The pozzolanic reaction was observed also in case of systems air lime–nanosilica. • The application of nanosilica up to 4 wt.% showed beneficial impact on compressive strength. This paper presents an experimental assessment of the effects of silica (SiO 2) nanoparticles on the properties and performance of lime restoration mortars. Mortars were fabricated using calcareous aggregates, and two different types of limes (air, hydraulic) and different amounts of SiO 2 nanoparticles. In order to isolate nanoparticles effects on mortars properties no dispersing or water reducing agents were employed. Several physical-mechanical properties, mineralogical compositions and microstructural changes of hardened samples have been investigated. It was observed that the application of nanosilica, without the usage of dispersing or water reducing agents, influenced the type of CaCO 3 polymorphs formed, the carbonation rates and the pozzolanic reactions. The application of nanosilica up to 4 wt.% resulted in the improvement of the mechanical performance. It was demonstrated that the usage of nanosilica without further additives may be used to tune properties of air and hydraulic limes according to the specific requirements for restoration of objects of cultural heritage. [ABSTRACT FROM AUTHOR]

Lime materials are in great demand for the restoration of the walls of historical buildings. However, lime coatings have insufficient resistance during operation. The purpose of this work was the modification of lime mortars with silicic acid sol in order to obtain more durable crystalline materials for construction purposes. A technology has been developed for obtaining a silica-containing additive, which consists in passing a liquid glass solution with a density of 1.053 kg/m3 through a cationic column and obtaining a silicic acid sol with a pH of 3–4 and a charge of (−) 0.053 V. The regeneration time and the amount of sol have been determined. Regularities of change in the radius of particles of silicic acid sol depending on age are determined. It is established that at an early age (up to 5 days), the radius of sol particles can be determined in accordance with the Rayleigh equation, and at a later age, in accordance with the Heller equation. The results of the calculation show that at the age of 1–5 days, the radius of the sol particles is 17.1–17.9 nm, and then the particles become coarser and the particle radius is 131.2–143 nm at the age of 19 days. The work of adhesion of silicic acid sol to lime and the heat of wetting are estimated. It is shown that the work of adhesion of water to lime is 28.9 erg/cm2, and that of the sol is 32.8 erg/cm2. The amount of heat Q released when lime is wetted with SiO2 sol is 15.0 kJ/kg, and when lime is wetted with water, it is 10.6 kJ/kg. [ABSTRACT FROM AUTHOR]

Today's society is increasingly aware of the conservation of architectural heritage and, at the same time, is committed to the use of new technologies in construction and the use of more sustainable construction materials. This work has a double objective, on the one hand, to develop new measurement equipment based on Arduino platform for the monitoring of moisture and temperature parameters, and on the other, to determine the evolution of these properties and the physical-mechanical characteristics of lime-based mortars used in rehabilitation works. An experimental campaign has been carried out where two types of hydraulic lime mortars have been used that differ according to the aggregate either, natural or mixed recycled ceramic. The results show how it is possible to monitor in real-time the temperature and moisture parameters in the mortars from the beginning of the setting process, which is of great relevance for the control of the execution process in restoration works. Besides, it has been possible to observe how lime mortars with recycled aggregate present good technical performance for use in rehabilitation works, although without reaching the physical and mechanical properties of traditional mortars.

Ammonium carbonate was used as the carbonation accelerator for air-hardening lime mortars in this study. Various analytical methods, including XRD, IR, TGA-DSC and SEM were employed to access the phase transformation, degree of carbonation and microstructural features of the lime-based mortars. The paper explores the correlation between the mechanical strength, microstructure of cured lime mortars and the composition/carbonation degree with the crystallization behaviors in Ca(OH)2/CaCO3 binders. The results indicate that ammonium carbonate significantly accelerates the carbonation reaction and increases the early mechanical strength of air-hardening lime mortars. The mechanical strength of these modified lime mortars can be comparable to that of natural hydraulic lime (NHL). The aggregation behaviors of nano-CaCO3 under kinetic control, are believed to contribute much to the compact pore-structures and robust mechanical strength of lime mortars. This viable accelerating carbonation method holds promise for enhancing the properties of various lime-containing building materials in conservation and modern buildings. • Ammonium carbonate is effective in accelerating the carbonation of aerial lime. • Lime mortars modified by ammonium carbonate rival natural hydraulic lime (NHL). • The mechanical strength is highly related to carbonation degree and pore structure. • Nano-CaCO 3 play pivotal role in compacting the pore structure of lime mortar. [ABSTRACT FROM AUTHOR]

This study examines the mortar materials used in the construction of the walls at the Archaeological Roman Fortification site (Ovidiu, Romania) on the shore of Siutghiol Lake. Several analyses were conducted to determine the mortars’ basic physical properties, mineralogical composition, and microstructural characteristics in order to describe the mortars used in the construction of the Roman fortress. The investigation utilized X-ray diffraction (XRD), energy dispersive X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM-EDAX), and differential thermal analysis (TGA-DTA). The results indicated that siliceous aggregates and lime binders were used in the production of the studied mortars, the structure was constructed in the sixth century, and the raw materials used to construct the site are of local origin. Using the methods mentioned above, there is the possibility of recreating the fortification’s mortar formula using contemporary materials and recommending intervention materials for the preservation of the archaeology of the Roman Fortification. Furthermore, this study opens up many other research opportunities regarding the reuse of mortars extracted from archaeological sites in the rehabilitation process by integrating them into new mortar recipes that can then be tested to compare the results with those obtained from standardized recipes.

The most used binders for coating and laying mortars are Portland cement and hydrated lime. The hydrated lime has been used for centuries due to its properties. However, the construction field has been modernizing and seeking improvements, which led to the use of industrialized mortars. Those mortars are made from a controlled manufacturing and dosing process and typically do not contain lime. Instead, it contains chemical additives that provide the same properties of lime(workability and water retention), without interfering with the compressive strength. Nevertheless, there are still gaps regarding the performance of these mortars, mainly related to the safety of buildings in fire situations. To evaluate these materials regarding a fire situation, the residual compressive strength was identified as one of the most important parameters. In addition, non-destructive tests, such as the ultrasonic test, has been proved to be a great tool to help in this evaluation. In this context, this work aims to investigate the relationship between the residual compressive strength and the UPV of industrialized mortars and mortars with lime, for usual strength classes (laying and coating mortars) subjected to high temperatures. From the results, lime mortars showed lower values for residual UPV. Moreover, the addition of lime was found to be a relevant parameter in evaluating the residual UPV of mortars, while the strength class, for a range of 5-20 MPa, did not show high relevance, indicating that mortars with and without lime should be studied individually. In addition, unlike many studies that propose a correlation without any standard methodology, this work proposes a correlation following a standard methodology and proves, through a validation with data from literature, that residual UPV and residual compressive strength are correlated through a logarithmic regression. Therefore, this work makes a great contribution by providing an estimation of compressive strength through an NDT testing, helping practitioners to adopt a thumb rule in the lab and in the field, especially in post-fire evaluation. [Display omitted] • The addition of lime is a relevant parameter in evaluating the residual UPV of mortars. • The addition of lime in mortars is more relevant to the microstructure of the mortar than to the f c. • The greater the cracking, the lower the f c of lime mortars. • There is a logarithmic relationship between Residual UPV and Residual f c of mortars. [ABSTRACT FROM AUTHOR]

Lime materials are in great demand for the restoration of the walls of historical buildings. However, lime coatings have insufficient resistance during operation. The purpose of this work was the modification of lime mortars with silicic acid sol in order to obtain more durable crystalline materials for construction purposes. A technology has been developed for obtaining a silica-containing additive, which consists in passing a liquid glass solution with a density of 1.053 kg/m3 through a cationic column and obtaining a silicic acid sol with a pH of 3–4 and a charge of (−) 0.053 V. The regeneration time and the amount of sol have been determined. Regularities of change in the radius of particles of silicic acid sol depending on age are determined. It is established that at an early age (up to 5 days), the radius of sol particles can be determined in accordance with the Rayleigh equation, and at a later age, in accordance with the Heller equation. The results of the calculation show that at the age of 1–5 days, the radius of the sol particles is 17.1–17.9 nm, and then the particles become coarser and the particle radius is 131.2–143 nm at the age of 19 days. The work of adhesion of silicic acid sol to lime and the heat of wetting are estimated. It is shown that the work of adhesion of water to lime is 28.9 erg/cm2, and that of the sol is 32.8 erg/cm2. The amount of heat Q released when lime is wetted with SiO2 sol is 15.0 kJ/kg, and when lime is wetted with water, it is 10.6 kJ/kg.

This research aims to revalue the possibilities presented by lime mortars for use in renovation and as cladding material on facades. The study focuses on analyzing the technical feasibility of lime mortars with the incorporation of residues from three types of thermal insulation materials: expanded polystyrene with graphite especially suitable for use on facades; expanded polystyrene for use indoors; and insulating mineral wool. The incorporation of these construction and demolition residues makes it possible to improve several technical performance aspects of lime mortars, and to incorporate circular economy criteria in the manufacturing process of these materials. The results showed that the incorporation of mineral wool improves the mechanical resistance to the bending of mortars, increases their durability against freeze–thaw cycles and salt crystallization, and reduces the final shrinkage of mortars. For their part, mortars with the addition of polystyrene-insulating residues reduce mechanical resistance, but also reduce thermal conductivity, and are lighter, which is why they are shown as a possible alternative for use in precast.

In addition to serving as documentation of cultural existence, historical structures are important part of the living environment. Thus, it is important to transfer them to future generations. Historical buildings that have been damaged over time due to various reasons are in need of conservation and restoration. However, methods applied with lack of scientific research can have harmful effects on the structure and create new damages. The scientific research on hydraulic, lime-based grout that is frequently used in the restoration of historical buildings is insufficient. In particular, the research on commercially sold lime-based grout needs more interest. The injection of grout is an irreversible technique and more scientific research can prevent unpredictable damages. Furthermore, although it is widely used, there are no national or international standards regarding the use of hydraulic lime-based grout. The aim of this study is to analyse the development of the grouting technique and the lime based grouts used in the restoration of buildings with historical masonry structure within the literature review context and to offer a contribution to the required standards and further scientific research. This research is an examination of the available resources in related topics in a chronologic order. First, the technique used to inject the grout during the restoration of buildings with historical masonry is described. Studies performed related to other grouts and mortars that contributed to the development of the use of hydraulic, lime-based grouts are discussed. Then, the development of the hydraulic, lime-based grout material and the test methods for this material are examined. There is also an analysis on the research performed with regard to the commercially available, hydraulic, lime-based grouts. Finally, the previous and ongoing research considering the use of this grout in Turkey is mentioned in the scope of this study.

Liesegang rings have been noticed in laboratory experiments with lime mortars but very few references mention their presence in mortars exposed outdoors. To date, authors have linked the occurrence of Liesegang patterns to mortars prepared with long matured limes, but here we show that very coarse and poor quality lime mortars may also develop similar patterns. SEM observations and EDS measurements on samples taken from exposed mortars show that calcium content varies along the banding sequence, and measurements made along naturally occurring banded patterns prove that the spacing law characteristic of the Liesegang phenomenon applies to them. One case showed that the carbonation banding follows a trendily revert pattern, while a second one fits in an equidistant-type pattern. The occurrence of such irregular patterns may be governed by the presence of a drying process superimposed on the normal diffusion process along the carbonation front. [ABSTRACT FROM AUTHOR]

Construction materials of a partly ruined Medieval church of Central Hungary were studied in details to assess its conditions and to obtain information on the phases of construction. At first, digital images were taken to create a 3D model of the remaining walls. The material properties were measured in situ using non-destructive test methods. Strength parameters of stone and render were assessed by Schmidt hammer, while moisture content was measured by a portable moisture meter. According to lithological descriptions and thin-section analyses limestone prevail in the monument. The most common Miocene limestone is represented by various lithologies, such as cemented macro porous limestone, fine-grained porous limestone, oolitic limestone and bioclastic limestone. Mesozoic micritic well cemented limestone and Tertiary limonitic sandstone were also identified at the ruins. The most common weathering forms are selective dissolution, multiple flaking and biological colonisation. Renders used in the structure represents the long history of the structure from Medieval lime-based mortars to Portland cement containing latest applications. The former one is composed of quartz send in lime binder. According to Schmidt hammer tests, the rebound values of the replacement stone is higher than that of the original porous limestone. There is a distinct difference in the moisture content of the stone and render. Orientation/exposure of the wall also influences the moisture content. The gathered information allows for designing better repair methods and helps in the planning of the maintenance of the medieval stone heritage. [ABSTRACT FROM AUTHOR]

• The potential of brick waste recycling and its use in aerial lime-based mortars is investigated. • The incorporation of brick dust in lime mortars generated a pozzolanic reaction. • Brick dust improved the compressive strength. • Brick dust increased the hygric and hydric expansion of lime-based mortars. To preserve architectural heritage for future generations, restoration materials such as mortars should be compatible with the historic substrate. Pozzolanic mortars are a compromise solution between Portland cement-based mortars and aerial lime-based mortars. This paper investigates the recycling of brick waste in the Meknes region of Morocco to formulate pozzolanic mortars. Nine different mortars were made using aerial lime, sand and brick dust. They were characterized in terms of shrinkage, color, mechanical and hydric properties. The study revealed that Meknes brick dust exhibits a pozzolanic activity and reduces shrinkage. Moreover, it increases hydric and hygric expansion, enhances mechanical strength and affects the color of mortars. An appropriate recipe for restoration mortars could then be proposed to restore regional architectural heritages, depending on the properties of their historic substrates. [ABSTRACT FROM AUTHOR]

• Lime powder mortars present higher carbonation rate in relation to lime putty ones. • The pore distribution is unimodal for lime powder mortars and bimodal for putty ones. • Water capillary rise coefficient is higher for lime powder mortars. • Lime powder mortars present higher compressive strength compared to putty mortars. • The aggregates' mineralogy does not affect significantly the mortars' characteristics. The aim of this work is to study the influence of calcium hydrated lime (lime putty or hydrated lime powder) to the chemical and physico-mechanical characteristics of lime mortars. The mortars were designed with the same mixing ratio of lime/aggregates and evaluated till 18 months of curing. The carbonation rate is evaluated via DTA/TG, the pore structure by mercury intrusion porosimetry and the hygric properties via capillary rise and water immersion tests. Mortars' shrinkage and apparent density were also measured along with mechanical strength and static and dynamic modulus of elasticity that were evaluated by using conventional mechanical tests and ultrasonic technique. The obtained results revealed that lime powder mortars present a higher carbonation rate and higher values of compressive strength compared to lime putty mortars. Lime powder mortars also exhibit a unimodal pore size distribution (while lime putty mortars present a bimodal one) and higher capillary rise coefficient and porosity accessible to water in respect to lime putty mortars. [ABSTRACT FROM AUTHOR]

• Mortars from the Roman Forum of Carthago Nova show a clear multilayered structure. • The mortars' composition varies considerably across layers (top to bottom). • TG allows quantification of cerussite, whose origin is uncertain in Roman mortars. • Hydroxyapatite linked to combustion of animals' bones was found in black pigments. • The materials are well preserved, and some mortars were likely coated (wax). This paper aims to study the construction technique and characterisation of original mortars and wall paintings at the Roman Forum district of Carthago Nova (Spain). A multi-analytical approach was conducted on original fragments using Optical Microscopy (OM), Field Emission Scanning Electron Microscopy (FESEM), colour tests (CIE L*a*b*) and contact angle measurements. Besides, the chemical composition was studied by X-fluorescence (XRF), Thermogravimetry (TG), X-ray diffraction (XRD) and Infrared spectroscopy using attenuated total reflectance (ATR-FTIR). The mortars showed a multi-layered pattern consisting of three distinguishable layers that were decorated with low-thickness coatings. The top layer composition was eminently calcitic, while the central and bottom layers were probably elaborated with pozzolanic materials. It is worth noting that unusual minerals as cerussite (PbCO 3) were identified in some layers, and probably associated to subsequent activities carried out in the site after Roman times. The top coating was made of hematite (Fe 2 O 3) for red decoration, whereas graphite (C) and hydroxyapatite (Ca 5 (PO 4) 3 (OH)) were identified in black coatings, which suggests the use of animal bones in the production of black pigments. In addition, the outer surface of some fragments was most likely coated with organic substances to enhance colour and durability. Finally, SEM examination and EDX analyses also confirmed some of the above findings and the existence of NaCl surface crusts due to natural weathering. [ABSTRACT FROM AUTHOR]

The Church of the Company of Jesus in Quito (1605–1765) is one of the most remarkable examples of colonial religious architecture on the World Heritage List. This church has multiple constructive phases and several interventions with no clear record of the entire architectural site, including the historical mortars. A total of 14 samples of coating mortars inside the central nave were taken, with the protocols suggested by the research team and a comparative sample of the architectural group that does not have intervention. The analysis presented in this paper focuses on mineralogical characterization, semi-quantitative analysis by X-ray diffraction and scanning electron microscopy with microanalysis of the samples. The results showed the presence of volcanic aggregate lime and gypsum, used in lining mortars and joint mortars. Mineralogical and textural composition data have allowed the mortar samples to be relatively dated.

Abstract The estimation of climate conditions and different moisture sources associated with the substrate composition and features in historical buildings is crucial to evaluate the substrate biodeterioration by filamentous fungi. Knowing the main agents and their frequency in substrates is relevant to propose conservation approaches focused on buildings preservation. Therefore, the mineralogic composition characterization of the historic building mortar coatings in Porto Alegre, RS was performed by binder/aggregate proportioning, x-ray diffraction, x-ray fluorescence, and thermogravimetric analyses. The microclimate conditions of indoor environments were evaluated through relative humidity (RH) and temperature recording sensors measurements. The qualitative and quantitative identification of filamentous fungi from the mortar coating was performed by microculture and DNA extraction for PCR and molecular analysis. The analyses indicated a mortar coating predominated by CaCO 3 and MgCO 3 with quartz sand and traces ratio between 1:2 and 1:5.4. The indoor microclimate had mean RH above 70% and a mean temperature above 20°C most of the time. Approximately 60 colonies of fungi were isolated, and 13 isolates were identified as the most frequent ones; among them: Aspergillus niger, Cladosporium sphaerospermum, Cladosporium spp., Purpureocillium lillacinus, Lecanicillium spp., Trichoderma atroviride, and T. harzianum. Highlights • The correlation between the indoor microclimate and fungal deterioration in a historical building was evaluated. • Different moisture sources influenced the fungal diversity and frequency. • The correlation between the mineralogical composition of historical mortars and fungal growth was estimated. • The fungal molecular identification was performed considering the substrate and regional constraints. [ABSTRACT FROM AUTHOR]

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• Comparison of Argical M1000, diatomite and brick dust pozzolans in lime mortars. • Comparison of direct and indirect methods used to determine pozzolanic activity. • Effect of pozzolanic lime mortar pore structure on freeze thaw resistance. • Optimisation of pozzolanic lime mortars for masonry in conservation applications. Degradation of hydrated lime mortars subjected to freezing and thawing is common in historic building conservation. The pozzolanic additions, Argical M1000, diatomite (diatomaceous earth) and brick dust, were evaluated for their ability to improve performance for up to 720 days. Pozzolanic reactions influenced the pore structure evolution, mechanical performance, and chemical reactivity of the mortar matrix. Argical-lime mortars exhibited a sudden failure, while a gradual reduction in mechanical strength was observed for mortars containing brick dust. A slower rate of failure in diatomite mortars was attributed to pore refinement, which was associated with superior freeze thaw performance. This study has advanced the current state of the art regarding how pore structure affects lime mortars' freeze and thaw resistance. Therefore it provides spesifications on how to optimise mortars for historic masonry. A key impact is the more effective use of lime mortars for conservation, thereby protecting heritage structures from degredation. [ABSTRACT FROM AUTHOR]

Four absorbent mortars were designed in this study and used as sacrificial desalinating media. The mortars comprised lime, sepiolite, nanosilica (72/3/25 by weight) and three admixtures (H 2 O 2 and two commercial aerators) and had a liquid/solid ratio of 0.9, a mean porosity of 40% and a mean pore size of 0.8–0.7 μm. These mortars were applied three times to ashlars exhibiting surface saline efflorescence on a church at Talamanca del Jarama, a town in the Spanish province of Madrid. The salts impregnating the wall were characterised with XRD, FTIR and Micro-Raman spectroscopy. The ion concentrations in the ashlars was studied with ion chromatography at 0.5 cm, 1.5 cm and 3.0 cm from the surface after each application and the inner and outer surfaces of the mortars were analysed with Micro-Raman spectroscopy to determine the desalinating efficacy of the mortars. The mortars designed mobilised and absorbed the soluble salts in the ashlars; as a rule, elimination was most effective in anions with a smaller ionic volume and therefore greater ionic mobility and when the salt concentration was high and superficially located. Three years after application of the desalinating mortars, the salt concentration in the ashlars treated was 50% lower than prior to treatment. [ABSTRACT FROM AUTHOR]

Almost all the façades of rural vernacular constructions were rendered in order to protect and decorate the masonry walls. Therefore, this study has been carried out in order to identify and classify the different vernacular techniques for producing mortar over history in a given geographical region through the combination of petrophysic, chemical and organoleptic analysis, going on to classify and date constructions for which there were no recorded data. The results show that mortars do indeed contain a wealth of information, which situates these constructions in a specific period of history and allows relationships to be established between construction stages and techniques. The results have also demonstrated that mortars are mainly composed of lime rather than gypsum as was erroneously assumed before the study. So, the determination of components and techniques has been considered a crucial aspect to be taken into account when working on the conservation, of contemporary aesthetic interventions for which the combination of petrophysical, chemical and organoleptic analysis is necessary to guarantee compatibility between existing mortars and new ones. [ABSTRACT FROM AUTHOR]

Two lime mortars were treated under laboratory conditions to assess the potential effectiveness of three consolidation treatments performed with: an ethyl silicate, a nanolime and a solution of barium hydroxide. The consolidation products were applied by direct contact capillarity. The duration and number of applications were adapted to the specific requirements of each product. Compressive and bending strength and drilling resistance were used to assess the potential effectiveness of the three treatments. The mortar made with a larger amount of a coarser aggregate showed lower porosity but a higher proportion of large pores, which was responsible for the observed higher increments in the resistance of the consolidated specimens. Compressive and bending resistance provided information on the consolidation action as a whole, while the drilling resistance measurements allowed also the identification of the consolidated thickness. The ethyl silicate was able to consolidate about 16 mm in thickness, while for nanolime this value only reached a maximum of 5 mm. The treatment with barium hydroxide showed a very distinct behaviour in both mortars reaching a larger consolidated thickness in the coarser mortar, while keeping the resistance increment ratio in a moderate value. The drilling data before and after treatment were interpreted in two ways; (i) with all the tests drilled in a same condition averaged and compared; (ii) after proceeding with a segmentation methodology addressed to identify the binding matrix and to detect the consolidation directly on it. The two methods proved to be complementary ways to characterise lime mortars and to study their consolidation. [ABSTRACT FROM AUTHOR]

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Recently, the use of lime mortars in the restoration of historic buildings has found a renewed interest because they can guarantee the required mechanical, chemical and physical compatibility with the existing substrate. Spontaneous occurrence of self-healing phenomena in lime-based mortars is well known; the possibility of engineering the self-healing capacity, through tailored additions, is therefore of the utmost interest with the aim of enhancing the durability of the building masonry restoration works. This work proposes a system for the evaluation of the self-healing capacity with reference to traditional and advanced lime mortars. The autogenous healing capacity of a reference lime mortar has been first of all evaluated. Then, the possibility of engineering the aforementioned capacity has also assessed, through both commercial crystalline admixtures and tailored encapsulated additives. These should work according to a twofold mechanism: first, the coated granules envelope a core of lime mortar with purpose of making it inert during the hardening phase. Secondly, once the coated granules rupture upon cracking and damage of the mortar, the reactive binder is released and undergoes a delayed hardening, which is responsible of the healing phenomena. The results show that the mortar is able to heal micro-cracks; moreover, the addition of the crystalline admixture enhances this capacity. The different kinds of employed coated granules were also able to induce a sensible self-healing, but they decrease the instantaneous compressive strength. [ABSTRACT FROM AUTHOR]

Three dumped raw materials, a tuff and two bentonites, obtained from two mining sites at the North Bohemian basin in the Czech Republic, have been studied in order to evaluate them as pozzolanic admixtures in lime mortars for employment in restoration of cultural heritage objects. After thermal activation (800 °C; 5 h), their pozzolanic properties were compared with those of commercial metakaolin. Quantitative phase analysis with the Rietveld method from X-ray powder diffraction patterns, morphological observations, as well as the Frattini and the modified Chapelle tests were performed. In addition, lime mortars, incorporating the fired materials, were prepared and subjected to simultaneous thermal analysis after a 28-day initial curing (20 ± 1 °C; 60 ± 5 % RH). The results showed that all three materials possess pozzolanic activity. However, when employed in lime mortars they did not result in formation of pozzolanic reaction products. Two methods were proposed to improve their reactivity; grinding to obtain finer particle size and removal of quartz content where necessary. [ABSTRACT FROM AUTHOR]

Researchers have related the manufacturing technique of plasters and stucco in the Maya area with their period of production but not with their architectural function. In this paper, we establish a relationship between those three features (manufacturing technique, age, and architectural function) in the plasters of the Maya site of Dzibanché in southern Quintana Roo. Dzibanché has abundant remains of stuccos and plasters found mainly in three buildings (Plaza Pom, Pequeña Acrópolis, and Structure 2). We used thin sections, SEM and XRD, and archaeomagnetic dating processes. The pictorial layer of Structure 2 was the earliest (AD 274-316 and the stuccoes and plasters of the other two buildings were dated to the Middle Classic (AD 422-531), but we obtained different archaeomagnetic dates for the red pigment layers found in the buildings of the Pequeña Acrópolis and thus we were able to determine their chronological order of construction. The raw materials and proportions were carefully chosen to fulfil the mechanical necessities of the architectonic function: different proportions were found in plasters of floors, in the external walls, and inside the buildings; differences between earlier and later plasters were also detected. [ABSTRACT FROM AUTHOR]

The study of external renderings in the scope of conservation and restoration has acquired in the last years great methodological, scientific and technical advances. These renderings are important elements of the built structure, for besides possessing a protection function, they possess often a decorative function of great relevance for the image of the monument. The maintenance of these renderings implies the conservation of traditional constructive techniques and the use of compatible materials, as similar to the originals as possible. The main objective of this study is to define a methodology of conservative restoration using strategies of maintenance of renderings and traditional constructive techniques. The minimum intervention principle is maintained as well as the use of materials compatible with the original ones. This paper describes the technique and products used for the consolidation of the loss of cohesion. The testing campaign was developed under controlled conditions, in laboratory, and in situ in order to evaluate their efficacy for the consolidation of old renders. A set of tests is presented to evaluate the effectiveness of the process. The results are analysed and a reflection is added referring to the applicability of these techniques. Finally the paper presents a proposal for further research.

Intervention in ancient buildings with historical and architectural value requires traditional techniques, such as the use of lime mortars for internal and external wall renderings. In order to ensure the desired performance, these rendering mortars must be rigorously specified and quality controls have to be performed during application. The choice of mortar composition should take account of factors such as compatibility with the substrate, mechanical requirements and water behaviour. The construction schedule, which used to be considered a second order variable, nowadays plays a decisive role in the selection of the rendering technique, given its effects upon costs. How should lime-based mortars be specified? How much time is required for the application and curing of a lime-based render? This paper reflects upon the feasibility of using traditional lime mortars in three-layer renders inside churches and monasteries under adverse hygrothermal conditions and when time is critical. A case study is presented in which internal lime mortar renderings were applied in a church in Northern Portugal, where the very high relative humidity meant that several months were necessary before the drying process was complete.

Portugal is one of the European countries in which built heritage is a testimony of its history. In this context, the legacy of the decorative glazed tile coatings of facades must be preserved and restored. This research is dedicated to the conservation of such facades in the city of Ovar, considered an example due to its rich heritage in glazed tiles, a high percentage of which requires a deep intervention. Therefore, this work is focused on the study of lime renders serving as a support for this type of tile facades. For this, samples were collected from several buildings in the city, targeting their mechanical and physical study with the aim of producing compatible mortars to be used for application of detached tiles in these buildings and generally for the repair of the facades with glazed tile coatings. For this purpose, four lime mortar formulations with different volumetric ratios were composed. The aggregates used were: ordinary river sand and local gravel. In three of the mixtures, metakaolin was added, with the intention of acting as an artificial pozzolan and thus improving the performance of these mortars. The use of a pozzolanic addition promotes hardening of lime mortars in cases when the ingression of carbon dioxide is low as is the case of mortars placed below glazed tile coatings. These mortars were also tested in the laboratory taking into account their physical and mechanical characteristics. The mechanical characteristics determined were: modulus of elasticity by two different methods, compressive strength and flexural strength. In turn, the physical characteristics determined were: water vapour permeability and water absorption by total immersion and capillary action. The best mechanical behaviour (compressive and flexural) was observed in the mortar with pozzolanic additions. Similarly, the value of the modulus of elasticity was better in mortars with pozzolanic additions. The performance of these mortars was also adequate in terms of water behaviour. The mortars revealed suitable characteristics for application in building conservation situations concerning coating with glazed tiles.