FAQs: Heritage services and mortar analysis

Mark Milevski, Materials Testing Specialist, Heritage Services

Mark Milevski is a geomaterials scientist with an interest in heritage and conservation. He enjoys being a part of “breathing new life” into heritage buildings so that they can have a second chance.

Stone Initiatives answers your FAQs about heritage services and mortar analysis.

What information do I get from a mortar analysis?

• XRD analysis of bulk fractions: A representative portion would be pulverised then analysed by X-ray diffraction to identify the minerals present. 
• Determination of cement/lime/sand content: A representative portion would be analysed to determine the key chemical constituents that can be used to calculate approximate cement/lime/sand volume proportions.
• Sizing of aggregate: The mortar would be added to a dilute acid solution to remove the acid-soluble fraction. The insoluble fraction (sand) would then be washed, dried, weighed and dry-sieved to provide a particle size range. 
• Aggregate colour and morphology: The sample would be examined under magnification to provide a description of its appearance including shape, colour and composition. A magnified image of the bulk mortar and dominant sand fraction and other relevant features (such as pozzolans and pigments) would be included within the report.  

How much mortar or render do I need to provide for an analysis?

For our team to provide you with a representative result, we require a minimum sample size of 100 grams of mortar or render (preferably palm-sized fragments). The sample should be supplied as ‘chunks’ freshly removed from the substrate and sealed in zip-lock bags. 

How long does mortar analysis take?

Four weeks is a general guideline, plus or minus one week.

Can I use cement products to strengthen or fix failing elements on my heritage structure?

Any mortar, render or pointing should always be softer and sacrificial (preferentially decay) to the ashlar or masonry elements. Mortar is cheaper and easier to replace than stone. Cement should almost never be used on any heritage structure, especially on those that were built before 1900.

Should I use a stone consolidator to strengthen the surface of my deteriorating stone?

A consolidation product may not always be the most suitable solution. Some stone types are not compatible and there is a risk of creating a hard skin, which can lead to accelerated decay. Please call or email us to discuss your project.

If you have additional questions about heritage services and mortar analysis after reading these FAQs, or if you’d like to organise a quote for your project, visit our contact page to get in touch.

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