Dating mortar who is hef dating after crystal

Posted by / 03-Apr-2019 13:05

Dating mortar

Physical testing (for durability assessment) Tests that determine pore structure such as water or gas permeability, freeze thaw resistance, porosity and pore size distribution provide data on durability.Mechanical testing (for performance assessment) Testing for compressive, tensile or flexural strength on prepared samples will determine suitability for different applications.Instrumental techniques for the analysis of organic materials - Gas chromatography with mass spectrometry; ion, liquid and thin layer chromatography These techniques are used (although rarely in mortars) for the identification of oils, resins, and proteins.Instrumental methods for characterisation of organic and inorganic materials - Thermal analysis (DTA, TGA, DSC) and infra-red spectroscopy (FTIR) Thermal analysis can be carried out on very small samples and can positively identify the composition of certain components, including calcium carbonate, calcium hydroxide, calcium sulphate, calcium silicate hydrates, and depending upon the constituents remaining after ageing, complex calcium silicate and aluminate hydrates.Photography is useful for documentation of condition.Light microscopy - Binocular microscopy; polarised light microscopy; thin sections The binocular microscope equipped with incident and transmitted tungsten light, with the potential for observation of samples in cross-polars, allows determination of the mineralogy and distribution of components and their interrelationship.

There are three main reasons for doing this: firstly, repair materials which match the originals will provide some continuity with the past, keeping intervention to the minimum; secondly, by matching the original materials and techniques closely, the repair materials will age in a similar way as the original; and finally, modern materials and techniques introduced in past repair work have often proved to be incompatible with the original, causing accelerated deterioration of building fabric.Generally these tests consisted of dissolving a sample in dilute acid to separate the acid-soluble from the insoluble.The soluble proportion is (often incorrectly) assumed to be the binder, (as it so often includes soluble limestone aggregate and calcareous clays), and the binder is assumed to be carbonated lime (which of course it often isn't).Analysis is carried out with differing goals, from a simple colour match to ensure a sympathetic 'matching' repair mix, investigative assessments and performance evaluations, to academic studies that attempt to determine the precise reasons for the remarkable durability of ancient mortars.Many analytical techniques are being employed, each with particular strengths and limitations.

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A calcium result, reported as calcium oxide, does not mean that calcium oxide is present.