Historic Mortars Research Articles

Prediction of compression strength of ancient mortars through in situ drilling resistance technique

The paper presents the results of a research project carried out to determine the mechanical characteristics of mortar in historical masonry buildings by drilling resistance technique (DRMS).A set of mortar mixtures have been produced in experimental campaigns covering different compressive strengths typical of historic mortars. The mortars have been obtained with different classes of binder and river sand with different grading curves. Specimens obtained were subjected both to flexural, compression and DRMS laboratory tests.Considering the results of the drilling measurement distributions, both the mode and the average value, the latter obtained after a statistical treatment in which extreme outliers are deleted, have been taken as reference values for each test performed. Effective correlations between the mode and average values of DRMS tests and the compressive strengths of the mortars are provided.Finally, a stepwise process to be followed for in situ use of DRMS is defined and applied to mortar joints of some existing masonry buildings in Tuscany (Italy).

Investigation of historical mortars from Belém do Pará, Northern Brazil

Belém do Pará, founded in 1616, still has layers of lime mortar on its historical buildings, which recurrently need restorative interventions. Intervention strategies need to include the use of building materials compatible with the original materials and, therefore, a good characterization of the original composition is necessary for the restoration of historical monuments. Thus, the main objective of this paper is the chemical, physical, and mineralogical characterization of historical mortars in Belém do Pará from the 18th and 19th centuries, as well as to evaluate their physical and mechanical properties. The results obtained showed the type of mortars used in different buildings and their main components, as well as the mortars behavior that helped the durability of the historic masonries. The conclusions leaded to useful information for seculars mortars restoration of northern Brazil.

Influence of Flax Oil Additive on Rheological Properties of Lime Mortar

Lime based mortars rank to the oldest used building systems used by human civilization worldwide. These materials offer suitable properties for various applications; however its low resistance in moist environment is their significant weakness. Hence, they were modified by number of additives and admixtures. The flax oil was applied to historic mortars to achieve hydrophobization, additionally this additive has considerable influence on the properties of fresh mixture as well. This paper introduces an experimental study dealing with the influence of flax oil on the properties of fresh lime based mortars with various water-to-binder ratios. The results of rheology properties were accompanied by the determination of mechanical performance, basic shrinkage and bulk density of hardened mortars.

FRESH STATE PROPERTIES OF LIME MORTARS WITH FLAX OIL ADMIXTURE

Flax oil has been used as mortar improving, hydrophobic, admixture already in ancient times. The paper describes the identification of flax oil in mosaic mortar from ca. 1900 by help of FTIR spectroscopy. This historic mortar was reproduced by nowadays raw materials and the influence of flax oil on consistency and air entraining of fresh mortar was tested. It was found that already small amount of oil caused significant air entrainment, which, simultaneously with water repellency action, may contribute to higher durability of mortar with oil admixture. The flux oil influenced also consistency of mortar; its presence caused higher flow value of mortar. Moreover, the introduction of the paper summarizes principal knowledge about action of natural admixtures in lime mortars and plasters on basis of current literature.

Innovative and green nanolime treatment tailored to consolidate the original mortar of the façade of a medieval building in L’aquila (Italy)

This paper presents an original, green and compatible treatment to consolidate the pointing lime plastering of the façade of a medieval Italian palace, subjected to detachments and pulverization phenomena. The cohesion between the mortar constituents was refurbished by an aqueous nanolime suspension, synthesized by a cheap, time/energy-saving and scalable method, here originally tested on historic mortars. The suspension showed a high reactivity, assuring a complete carbonation in few hours, “restoring” the binder fraction with a new-formed network of calcite nanoparticles. The treatment efficacy was evaluated by chemico-physical, mineralogical and mechanical characterization both on untreated and treated specimens.

TG-DTA and FTIR analyses of roman and later historic mortars from Drobeta-Turnu Severin region

The study shows the analysis of the various Roman mortars in the survival structure of the Danube Bridge in Drobeta-Turnu Severin, Romania, which is particularly relevant, and the results provided will help clarify the technology used for its construction through spectral, XRD and thermoanalytic techniques. It is intended to establish similarities or differences between the studied subjects. This paper highlights the complementary nature of the various techniques: XRD for the identification of major crystalline phases, FTIR for a more detailed evaluation of the composition comprising non-crystalline and TGA phase for the quantitative determination of volatile phases (especially CO2 and H2O).

Raman Microspectroscopic Imaging of Binder Remnants in Historical Mortars Reveals Processing Conditions

Binder remnants in historical mortars represent a record of the connection between the raw materials that enter the kiln, the process parameters, and the end product of the calcination. Raman microspectroscopy combines high structural sensitivity with micrometre to sub-micrometre spatial resolution and compatibility with conventional thin-sectional samples in an almost unique fashion, making it an interesting complementary extension of the existing methodological arsenal for mortar analysis. Raman spectra are vibrational fingerprints of crystalline and amorphous compounds, and contain marker bands that are specific for minerals and their polymorphic forms. Relative intensities of bands that are related to the same crystalline species change according to crystal orientations, and band shifts can be caused by the incorporation of foreign ions into crystal lattices, as well as stoichiometric changes within solid solution series. Finally, variations in crystallinity affect band widths. These effects are demonstrated based on the analysis of three historical mortar samples: micrometric distribution maps of phases and polymorphs, crystal orientations, and compositional variations of solid solution series of unreacted clinker grains in the Portland cement mortars of two 19th century castings, and the crystallinities of thermal anhydrite clusters in a high-fired medieval gypsum mortar as a measure for the applied burning temperature were successfully acquired.

Quantitative Analysis of Historic Mortars by Digital Image Analysis of Thin Sections

Abstract In restoration work, the compatibility between old and new building material is the key point for sustainable repair of buildings or monuments. Consequently, conservation scientists are looking for an alternative method to the traditional procedures to determine the aggregate grading curve and the binder/aggregate-ratio of the historic material. The problem of using the traditional methods is the frequent major intervention in an existing building. These destructive methods are not allowed. Whereas, to get information about the historic mortar, a new technique, the digital image analysis (DIA), is applied in this paper. Moreover, small amounts of the historic material have already been prepared as thin sections and analysed with a microscope. Modern microscopy techniques allow investigations of quantitative and qualitative composition of historic material. Incentive of this work was to get all the required information to recreate the historic mortar by using the DIA with an open source program only at one thin section. In addition, to examine the accuracy and the significance of the DIA, all results were compared with a known mixture, and in a second test series, the results of the DIA were compared with the traditional methods. The results show that the DIA of thin sections of a historic mortar is highly effective for analysing decisive factors like the binder/aggregate-ratio and the grading curve of the aggregates. Furthermore, it is possible to analyse the mortar only by having one thin section using an open source program ImageJ. Especially in the case of carbonate rock as aggregate, DIA is the only method to analyse these characteristics of a mortar.

Electrical and mechanical properties of historical mortars in Bursa/Turkey

This paper focuses on the electrical, physical and mechanical characterization of the ancient mortar (khorasan mortar) materials of precious structures, the Ali Pasa bathhouse, Candarli Ibrahim Pasa bathhouse, Hasan Pasa bathhouse, Iznik Castle and Tophane rampart historical constructions located in the West of Turkey, in Bursa. An exhaustive description of the materials has been obtained to enriching the knowledge on historical construction materials. The definition of the physical and mechanical properties of the materials, sophisticated laboratory tests were performed such as compressive strength, point loading, weight loss in acid, specific porosity, density and water absorption tests. Microstructure investigations and electrical resistivity measurements were also performed on the ancient mortars. The good correlations were obtained between electrical resistivity and mechanical properties of historical mortars as result of relations between them. The experimental investigation has allowed a better understanding of the remote origin of these structures.

Mineralogical, Textural and Physical Characterisation to Determine Deterioration Susceptibility of Irulegi Castle Lime Mortars (Navarre, Spain).

Archaeological lime mortars from the Tower Keep and West perimeter wall of Irulegi Castle (Navarre, Spain) were analysed to determine susceptibility to deterioration. Chemical, mineralogical, textural and physical characterisation was performed by different tests and multianalysis techniques in order to determine the intrinsic features of the original historical mortars at the castle. Samples from the Tower Keep are more prone to deteriorate compared with the West perimeter wall due to high water absorption capacity and high porosity. A high degree of pore interconnection, high desorption index and the presence of high pore volume in the 0.01 to 1 µm size range affect the mortar durability since pores retain water longer inside the mortar. Local environment conditions with persistent annual rainfall, high humidity and temperature variations contribute to the decay process of the original mortar. Characterisation of historical mortars not only allows better understanding of susceptibility to deterioration but also helps the design of compatible and durable repair mortar for future interventions on historical heritage. Compatibility of new materials with the historical mortar will be ensured by studying mortar characteristics and properties.

Mineralogical Analysis of Historical Mortars by FTIR.

A method for quantitative mineralogical analysis by ATR-FTIR [1] has been used first time for analysis of historical mortars. Mixtures of different minerals and gypsum were used in order to measure the minimum band intensity that must be considered for calculations and the detection limit. In this way, the molar absorptivity coefficient in the Lambert–Beer law and the components of a mixture in mol percentage can be calculated. The GAMS equation modeling environment and the NLP solver CONOPT (©ARKI Consulting and Development) were used to correlate the experimental data in the samples considered. The characterization of the vernacular mortars by FTIR analysis identifies the predominant minerals of the samples, and in conjunction with XRF and XRD, shows the exact composition of historical mortars, which will optimize the restoration and conservation of monuments, preserving our heritage.

Investigations of Hellenistic Mortar from Umm Qais (Gadara), Jordan

Ancient mortars have been widely studied, in connection with both diagnosis and applications required for restoration. This study is primarily based on analyses of different mortar samples from a Hellenistic temple. The study was done by means of a polarizing microscope equipped for observations in transmitted and reflected light; and X-ray powder diffraction (XRD). Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM-EDS) were also used to confirm and supplement the microscopic data, and wet chemical analyses were performed on the acid filtrate for soluble oxides of Fe, Al, Ca, Mg, S, Na and K. Chemical and petrographic analysis were used to determine chemical composition and physical properties, which in turn provide an in-depth understanding of the structural behavior and durability characteristics as they relate to the composition. The results show that the plaster used was a lime-based mortar. The cementing binder was a lime (identified by spot test) with fossilized shell, very fine grain size quartz, and some other minerals as the aggregate. The EDS analysis showed the presence of calcium and a small proportion of magnesium; in addition, silicon, aluminum, potassium, and iron were detected. Possibly, the silicate compounds contributed to the hydraulic component. We found strong similarities among mortar samples used in the temple. Physical methods provided useful information on the mineralogical compounds and the surface structures of samples, allowing for the postulation of deterioration mechanisms and overall decay, including the identification and crystalline morphology of reaction products and salts. These results aid in both understanding the technology of historic mortars and planning the restoration of these mortars.

Prediction of Compressive Strength for Heterogeneous Mortars from Drilling Resistance Data

ABSTRACT The characterization of historic mortars applied in construction is required in many situations, namely for their conservation. In this sense, the drilling resistance test has been being explored by the scientific community, since it has the unique feature of assessing the material strength in depth with very low intrusion. However, the drilling profiles returned by heterogeneous and weak mortars are very irregular which has been considered a limitation of the technique. This article discusses the reasons for the reported irregularity, showing that this supposed drawback is an inevitable outcome in the case of heterogeneous materials and that the statistical analysis of the drilling data can provide important information on the material characteristics. Additionally, it is shown that compressive strength obtained in conventional tests is also very affected by the material’s heterogeneity. A prediction model for compressive strength is established from drilling data collected on 16 low-strength mortars of diverse strength and heterogeneity degrees. This model, applicable to mortars with compressive strength values below 4–5 MPa, showed a mean error of less than 0.5 MPa. Thus, it is possible to predict the compressive strength for a large number of lime-based mortars with a reasonable confidence. The accuracy of the model is then demonstrated on a different set of mortar specimens, composed of six test cases.

Characterization of Historic Mortar from the Architectural Decoration and Plaster of Rocky Temple of Verjuy in Maragheh, Iran

Characterization of Historic Mortar from the Architectural Decoration and Plaster of Rocky Temple of Verjuy in Maragheh, Iran

An archaeometric approach of historical mortars taken from Foligno City (Umbria, Italy): news insight of Roman Empire in Italy

This research has been focused on the study of mortars from four bridges of the ancient city of Foligno (Umbria, Italy), located along the old path of the Topino-Tinia River. An archaeometric study was undertaken to analyse ten archaeological samples in order to define textural features, chemical composition and raw materials used for their production. For this purpose, different analytical methods were used, such as polarising optical microscope (POM), X-ray diffraction (XRD) and electron microprobe analysis coupled with energy-dispersive spectrometry (EMPA-EDS).

Performance of lime-based mortars at elevated temperatures

The properties and preservation state of historic mortars are closely related to various aspects, such as their constituents and the pathology symptoms they confront, due to extreme environmental conditions or accidental actions (i.e. earthquakes, floods, landslides and fire). Despite the fact that in the recent decades there is extensive research on the impact of elevated temperatures on cement based materials (cement mortars, concrete), there are no relevant studies concerning historic or repair materials. Taken into account that during their service life, historic structures may be subjected to accidental fires (limited or total), the resistance of their building materials to extreme temperatures seems to be a parameter that should be further investigated. To this direction, the paper focuses on the study of a series of lime-based mortars, designed for restoration works, exposed to a range of elevated temperatures starting from 200 °C to 1000 °C. The physico-mechanical properties of the mortar specimens were tested before and after their 2 h maintenance at different temperatures, regarding weight loss, volume change, porosity, apparent specific gravity, dynamic modulus of elasticity, flexural and compressive strength, while macroscopic and microscopic observation was also realised. The evaluation of the results showed that lime-based mortars preserved their structure and characteristics after their exposure to elevated temperatures, while in the case of lime-pozzolan matrix the resistance of the specimens was extremely high, compared to the other binding systems tested.

Scanning Mortars to Understand the Past and Plan the Future for the Maintenance of Monuments.

The effect of microstructure on macroproperties of building materials was the initiation in order to use microscopic techniques for studying the materials' behavior. Primer role among the different techniques has the scanning electron microscope (SEM) as it provides much information in an easy and understandable way. SEM has been used in almost every study of the last decades, dealing with historic and repair materials to complete the analysis performed. In the case of historic mortars, it is a unique technique as it requires a small representative sample and without any intense treatment important information derived from an almost unknown sample including damage detection, phase identification, and microanalysis. It is usually a complementary method of analysis but a precious one as the gained results from the analysis of old mortars are used for designing compatible repair materials for restoration purposes. In the paper, the long-term use of SEM in studying both old authentic and innovative repair mortars is presented.

Mixed-mode SPE followed by GC-MS analysis to determine water soluble organic compounds in aerosol and historical mortars affected by marine atmosphere: The case of Punta Begoña Galleries (Getxo, North of Spain)

This work describes the development of an analytical procedure for the determination of short chain dicarboxylic acids (C2-C10) both in aqueous and solid matrices such as aerosols and mortars. The developed and validated methodology was based on the preconcentration of compounds by means of mixed-mode solid phase extraction and gas chromatography-mass spectrometry, regardless the analyzed samples. In the case of solid samples, a prior extraction of target compounds using ultrasonic probe-assisted solid-liquid extraction was required. In general terms, the developed procedure rendered good results in terms of accuracy (apparent recoveries in the range 90–130% and 86–98% for marine aerosol and mortar samples, respectively) and repeatability (%RSD < 25%) except for those compounds interacting more strongly with the solid matrix and being more reactive. The method was applied to detect dicarboxylic acids in marine aerosol water samples and in mortars of a 20th century historical building (Punta Begoña Galleries, Getxo) located in a coastal environment (Biscay Gulf, Basque Country, Northern Spain) with industrial activity. According to the results, harbor activities may have effect on the concentrations of dicarboxylic acids found in both matrices since the façade of the building exposed to the industrial harbor (southwest orientation) appears to be more contaminated than the one oriented to the northwest.

Valorization of organic additions in restorative lime mortars: Spent cooking oil and albumen

Air- and formulated lime mortars with pulverized brick waste were synthesized with addition of two organic waste-based additives: spent cooking oil and albumen. The addition of spent oil in the mortar induced significant hydrophobic effects, but decreased permeability values and setting kinetics. Parallel additions of oil and albumen in lime mortars significantly increased their hydrophobicity and superficial durability without retarding their setting time thanks to role of fatty acids and unfolded proteins under alkaline conditions. The parallel valorization showed high potentials in synthesis of restorative mortars design with low environmental impact and high respect to the feature of historic mortars.

Study of the historical mortars of the Holy Aedicule as a basis for the design, application and assessment of repair mortars: A multispectral approach applied on the Holy Aedicule

The rehabilitation of the Holy Aedicule of the Holy Sepulchre in Jerusalem, completed in March 2017, aimed to address the deformation problems encountered after its most recent reconstruction in 1810. A diagnostic study performed by the National Technical University of Athens (NTUA), indicated the cause of the deformations and revealed the Aedicule’s structural layers. The results permitted the design, selection and application of compatible and performing restoration mortars, while the assessment of their application was achieved through a multispectral approach and in combination with an integrated analysis throughout the rehabilitation project. The results acquired through analytical and non destructive techniques show that compatibility was ensured and the structure was adequately strengthened and concludes in a methodological approach regarding all stages of a rehabilitation project of a complex multilayered monument.