Lime mortars and plasters

Although the origins of Classic Maya civilization can be traced back millennia, much focus in the popular imagination continues to be on the transitional phase toward the end of the Classic Period colloquially known as the Maya “collapse.” The main objective of this paper is to shift focus to the resilience of Classic Maya society and contribute to the growing spotlight on Prehispanic Maya environmental resource conservation practices. From agricultural terraces, elaborate reservoir systems and careful agroforestry practices to burnt-lime pit-kilns, Classic Maya civilization supported massive populations in a challenging tropical forest environment for over 700 years. Toward the end of the Classic Period, inhabitants of the Puuc region of the Northern Maya Lowlands recognized that they were dealing with population-induced environmental stresses, possibly exacerbated by natural climate change. Their development and widespread use of a fuel-efficient burnt lime pit-kiln technology during this period is an example of socio-ecological adaptability in the form of communal environmental resource management. This paper evaluates Late and Terminal Classic Period Puuc resource conservation through the lens of Resilience Theory and argues for the importance of adaptability and a willingness to change in response to climatic or environmental variability – a lesson that is worth heeding by contemporary society.

Currently, potters in the State of Morelos doing the
drying process of molds in shaded areas using
considerable time, through direct sunlight and using
energy waste furnaces. However, these processes
reduce the continuity of production, quality and shelf
life of the molds to expose them to temperatures over
55°C or in direct sunlight. Therefore, an agreement was
established CANACYNTRA-MORELOS-CENIDETSEP,
which found funding through the Government of
the State of Morelos-CONACYT, to carry out the
design and construction of a dryer molds that lengthen
the life of molds, used waste heat from ovens and solar
energy, easy reproduction and reduce the time and
movements during this critical part of the process. In
this work a methodology of evaluation of the dryer is
presented that allowed to detect opportunities to
improve their performance. It was found that the dryer
has a constant drying 0,05 and its time of drying was of
5,0 days. Also, it was found that the efficiency of solar
collectors limits the efficiency of the entire system.
Keywords: drying, dryer molds, design of a dryer
molds, construction of a dryer.

Tis report is a documentation report describing the behaviour of soapstone and greenschist conservation test fields as Nidaros Cathedral (Trondheim, Norway) after their establishment in July 2000. Moreover, the report describes experiments with lime mortars mixed at high speed* and used additionally at established test fields in June 2001.

The test fields have been established in order to obtain long-term experience with common and new stone conservation products. Until now, there is no experience with such products used on soapstone and greenschist world wide.

Although several of the products generally appears to have given good results after 1-2 years since the application, this is of course too short time in order to state anything for certain. Thus, a further 4-5 years of careful monitoring is strongly recommended.

If stone conservation materials have to be applied during the on-going restoration of the choir (e.g. for fixing scales), we recommend using HSM high-speed mixed lime-mortars as described in this report. These mortars are relatively "loose" and will probably not prevent removal and re-treatment in the future. Alternatively CalXnova, which is somewhat "harder" can also be considered. Using products based on ethyl silicate is not recommended before the long-therm monitoring of the test fields and proper analysis of the products behaviour have been carried out.



* as proposed and developed by Andreas Franz since 1999 and used in the conservation of plasterwork and wallpainting restoration

Research focusing on the 16th century original Renaissance sgraffito techniques has been in progress since 2012. It aims to specify the techniques utilized by sgraffito makers and to provide an evidence for the process by scientific methods. Primarily, the research concentrates on the area of South Bohemia. Non-invasive visual observation and documentation under the raking light illumination formed the basis of the investigation, complemented with laboratory material analysis. Based on the investigation, some characteristic features of Renaissance sgraffito were identified in the surveyed area and it led to a description of two specific methods of shading – coloured with a brush and smoothened by a trowel, so-called ‘trowel shading’. Both techniques work with middle grey tones and this visually interconnects sgraffito with monochromatic chiaroscuro painting. Detailed analysis carried out on two selected shaded sgraffiti from towns of Telč and Slavonice characterised the used raw materials, mixing ratios, and character and thickness of individual layers. Based on the analysis, local sources of materials were identified and subsequently, material copies were prepared with the aid of knowledge concerning historic lime production and processing technologies. The replicated mortar mixtures were evaluated on trial panels (workability, application methods, various surface finishes, setting and hardening, duration of time breaks between individual layers and/or scratching). The practical trials proved the connection between properties of the used materials (that predefined the use of the artistic technique including the ‘trowel shading’) and the final appearance of sgraffito decorations. Materials and technological copies facilitated a reconstruction of the Renaissance sgraffito technique originally used in the surveyed region and the newly gained knowledge and skills were subsequently used to restore a sgraffito façade in Slavonice.

The energy performance of historic buildings needs to be improved in a sustainable way while preserving cultural-historical values. A building material such as hemp-lime could fulfill a new function in the renovation of historic buildings. The objective of this project was to find an appropriate and resource-efficient method for additionally insulating plastered historic buildings that is compatible with the timber or brick structure, increases energy efficiency, creates a healthy indoor environment and contributes to preserving cultural-historical values.
The aim of the project was also to investigate hemp-lime as an additional insulation material in a cold Swedish climate with tough moisture conditions. It was essential to clarify the conditions for microbial growth on the material. An additional aim of the project was therefore to evaluate the risk of microbial growth on hemp-lime and to find key values for its critical moisture levels.
Use of hemp-lime as additional internal insulation on salt-withering brick masonry has also been investigated. Here the project has also focussed on understanding the behaviour of salts in masonry, their harmful effects and measures that can contribute to minimizing damage. Therefore, hemp-lime was tested and evaluated as internal additional insulation material to see if it could contribute to an altered microclimate with altered salt transport and thereby reducing salt damage to the plaster surface.
There is a large stock of durable historic buildings, built between the 1700s and the 1930s, that were built with lime-rendered timber or brick structures. Both of these building techniques became more common during the 19th century when cities were built with increased demands on fire protection and thermal comfort. Today, these buildings are often in need of maintenance or renovation, and in connection to this they need to be adapted to modern requirements on thermal comfort and energy efficiency. At the same time they possess high cultural-historical values and they must therefore be adapted/ maintained/renovated with great care, with traditional materials and methods and with compatible solutions.
The result of this project has shown that hemp-lime works very well for additional insulation of historic timber or brick buildings. Measured reduction of energy use for heating was 33-53% in the case studies compared to the original design. Additional insulation of hemp-lime gave a good moisture balance in both the masonry and the wooden structure, provided that it is combined with an appropriate lime render that is customized for the construction. As an internal insulation on salt-damaged brickwork, the hemp-lime gave a more stable microclimate with reduced number of salt crystallization cycles and therefore delayed damage mechanisms. Hemp-lime can contribute to a good acoustic environment and maintained fire protection. Hemp-lime can be used where cultural historical values should be preserved. This applies primarily to buildings that are facing renovation needs where a material is required that is compatible with both timber and brick walls as well as the traditional lime render, all of which will continue to constitute cultural-historical value-bearing elements in the building.

Architectural paint research carried out by the Colonial Williamsburg Foundation in collaboration with the Bermuda National Trust has shed light on how early houses on the island were constructed and finished from the late 17th century to the present. This is the first comprehensive effort to study historic Bermuda architecture through paint analysis, and the findings elucidate uncommon uses for a common finish: limewash. Our research shows that exteriors and interiors were rendered with stucco and plaster made of native limestone and the island's distinctive pink calcareous sand. Limewashes were also applied inside and out, from the ground to the rooftops. Most were unpigmented (white), but earth pigments were added regularly to create a stunning variety of hues from pale pastels to rich reds, oranges, yellows, and browns. Limewashes are inherently brittle and can present significant challenges during sampling and analysis. These can be overcome with careful in situ documentation, collecting and mounting larger samples, and using ultraviolet light and digital enhancements to differentiate between successive layers.

This paper focuses on three different ingredients used to create hydraulic mortar: volcanic ash, crushed terracotta, and plant ash. Each one imparts somewhat different characteristics to the mortar and has a different processing method, which would have affected the chaîne opératoire of the building site. One goal is to examine these characteristics and processes. A second goal is to examine some problems in the terminology used to identify the ingredients. How can choices in terminology, such as "crushed tile mortar" vs. "crushed terracotta mortar" or "mortar with charcoal" vs. "mortar with ash", affect our understanding of the significance of choices made by ancient builder? I argue that using precise and objective terms to describe the ingredients in the mortar is an important step in being able to determine source materials, which in turn can provide insight into organizational practices on the worksite.

Proyecto IdaVe The archaeological site of Santa Maria's Sé-Cathedral is located in the parish of Idanha-a-Velha (Portugal). Roman muni-cipium in High Imperial Era, when structures dated to the First and Second Centuries AD are documented, it appears that this city was known as ciuitas Igaeditanorum and developed a reputation along the Fourth Century AD. as a new Episcopal See. In this moment a Christian cult building was erected from another one in an earlier structure. This last building persists even in Islamic Period, at the same time that another new Mozarabic structure, that was added to the complex at the end of the Ninth Century. Given the presence of numerous phases of occupation and therefore, a several techniques and materials construction, archaeological direction decided to analyze some constructive elements like mortars present in joints, coatings and plasters of different rooms. Different macroscopic techniques were developed using high resolution images taken from, combined with the use of software that analyze the data obtained from colorimetries test and the spectral analysis from the mortars cross sections. Relevant results have been obtained in relation to the quantitative characterization and the composition of each mortar. Location of Sé-Cathedral´s archaeological complex in Idanha-a-Velha (Portugal) Sampling areas inside and outside the main building Particle size analysis by means of colorimetries, obtaining area and perimeter coefficient of all grains and developing a 3D scan of the surfaces. Macrophotografies of IV1 to IV8 samples, showing the difference between them. I DAÑHA

Lucknow was a major centre of Architecture and Culture during the fall of Mughal empire and British rule. Some scholars of the time compared the city with the likes of Istanbul for its skyline and architecture. Apart from many unique aspects of Lucknow which makes it distinct from the preceding Mughal architecture, use of lime stucco is a major distinctive feature. While use of lime stucco was present during the Mughal as well as Sultanate period, it evolved into a much sophisticated and intricate type and was used extensively in the Nawabi period in Lucknow. It was in Lucknow that the lime plaster was used on the exterior of the buildings in place of typical stone cladding in Mughal buildings. This article is a primary study of the distinctive attributes of the lime stucco of Lucknow. Author attempts to categorise the lime stucco work on the basis of patterns and functions.

En la presente investigación se exponen los distintos análisis, tanto químicos como reológicos, realizados a las pastas de cal con diferentes tiempos de añejamiento, y se evalúa el efecto que tiene el tiempo en su composición estructural y en su comportamiento físico.

This paper will present both petrographic and
preliminary chemical analyses which indicate that waterproofing
mortars in the Fountains of Peirene and Glauke, at the Asklepieion
and its associated springs and at the springhouse of Upper
Peirene on the Acrocorinth had hydraulic properties which were
previously unrecognised in Pre-Roman cements in this region. The
waterproofing mortars of pre-Roman Corinth demonstrate a high
degree of technical understanding of the production of lime-silica
cements, which has otherwise been previously overlooked.

There is a rapid development of earth construction the last few decades followed by an increased interest in scientific research in this field. One of the issues that have arisen is which soils are suitable for construction
and can be designated as construction soils and which are not. Thus, the main objective of this paper is to investigate the relation between physical soil properties and mechanical properties of the dried building material. In this context, the Cation Exchange Capacity (CEC) of the soil is investigated in this research as an innovative tool in soil assessment for earth building. The distinct advantage of CEC is its dependence on clay type and organic matter apart from clay content, which is the soil property most frequently used in soil assessment for building purposes. This study focuses on earth mortars, on which little experimental research has been carried out despite their widespread use. In order to overcome the issues often mentioned in literature of using a certain soil and then generalizing the results, it was decided to use a wide range of soils with different textures from various regions of Greece. So, 26 soils were collected and a total of 49 earth mortar mixes were fabricated in two phases. The soil properties assessed were texture, Atterberg limits, CEC, mineralogy and organic matter content, while the hardened mortar properties assessed were compressive strength, flexural strength, dry density and linear shrinkage. It was found that CEC provides stronger correlation with compressive strength and linear shrinkage than clay content and Plasticity Index. A linear correlation between linear shrinkage and compressive strength was also established. Finally, it is shown that the soils with high organic matter content used in this research, are unsuitable for earth building despite having sufficient compressive strength.

On the use of mortar at medieval Nidaros Cathedral, Trondheim, Norway. The  Baker  Memorial  Lecture  was  given on  Friday  8th  September  2017, in  the  Great  Hall  of  the  Archbishop’s  Palace, Trondheim, Norway, during the Conference of The Building Limes Forum.

Brita lavada: (washed gravel, in direct translation) is a decorative coating technology with a mortar based on cement, local Madeira basalt gravel and black pigment, currently used for masonry rendering on 20th-21st century Madeiran built heritage simulating stone masonry or cladding. Comparison of Brita Lavada and other cement based coating mortars was made regarding physical behaviour. The Brita Lavada shows high mechanical strength, acceptable water absorption and good water vapour permeability, what can justify its good durability on site and continuous application. The previous justify the interest on preserving the technology and is an example of optimised used of a local material, in the case a very hard basalt, with no possibility to be used for stonework, as a specific resource for a traditional, durable, eco-efficient decorative coating.