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Abstract: The time dependent deformation of natural hydraulic lime mortar (NHL3.5) through creep and shrinkage under load, in the first 63 days after mixing, has been investigated. An apparatus was constructed to measure the dimensional changes of eight individual specimens simultaneously. The influence of load on deformation rate was found to decrease with time during the experiment. The rate of decrease in load dependent deformation, creep, with time was shown to be inversely proportional to the extent of carbonation. This observation supports the theory that deformation can be explained by the dissolution of calcium hydroxide crystals under stress and subsequent re-precipitation of calcite in areas free from stress. [Copyright &y& Elsevier]

Abstract: This paper, and the research it describes, examines the benefits and importance of good site practice for the aftercare of lime mortars and renders. The control of moisture is explored in relation to mortar development. This work shows the way in which proper aftercare in terms of wetting, drying and protection enables lime mortars and renders to perform at their best. It is important that Architects, Engineers and specifiers can rely on craftspeople who understand the need for aftercare and ensure that best practice is followed. This paper provides a scientific explanation of how the traditional practice to control moisture, before and immediately following the application of building limes, works to improve set and durability. Scientific reasons for the traditional site practice of damping down the background to application of lime mixes, and the subsequent tending of finished work, are explained by reference to laboratory research developed for the purpose. [Copyright &y& Elsevier]

The mosaic coving at the Grade II* listed Freemasons’ Hall in London is an example of a mosaic on an Art Deco steel-framed building. Microstructural and chemical characterisation of loose mortars and tesserae were undertaken to inform conservation efforts and advise whether a protective coating was needed to prevent further fading of gold gilding. Rigorous testing used optical imaging, scanning electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis, Raman spectroscopy, X-ray diffraction, and thermogravimetric analysis with differential scanning calorimetry. Laboratory evidence demonstrated the glass tesserae were created using traditional techniques. The glass tesserae were soda-lime-silica glass with lead. The gold glass tessera was produced in the ancient Roman style which included a glass cartellina layer, so further protective coating was not needed. Historical records confirmed sheets of mosaic tesserae were prefabricated in Italy. The grout and thin-set mortar were the same low hydraulicity mortar mix, which enabled mosaic tesserae positions to be adjusted as required. The bedding coat mortar was a hydraulic cement mortar that was applied on top of an early example of foamed mortar from 1932. This unique study analyses a traditional style mosaic that was installed during a pivotal point in construction history where foamed mortars and steel framed buildings were introduced. It demonstrates how archival research and laboratory testing of small-sized samples enhance the building’s significance and architectural interest by improving the knowledge of its history. [ABSTRACT FROM AUTHOR]