Lime Mortar & Sand Analysis

The Director of SMT Associates commenced the Post Graduate Diploma in Building Conservation based at Reading University in 1998. As part of this course he prepared a 20,000 word paper on the use of lime in traditional buildings. As part of this study many historic lime mortars were analysed by acid dissolution and thin section analysis.

Matching mortar designed for the National Trust Botallick mines conservation. Original samples each side of the square pallet with the new mortar.

We are able to offer these services to our clients where it is important to match historic mortars. A small sample of the original lime mortar is collected from site. The selected sample is dried, weighed and examined both by eye and under a binocular microscope at up to x 40 magnification. The sample was crushed, the binder separated from the aggregate by dissolution in dilute hydrochloric acid and the relative weight proportions of binder (lime, gypsum an cement) to aggregate is determined. The characteristics of aggregate (and other acid-insoluble materials) is undertaken by means of sieve separation and further microscopic examination.

The analysis and interpretation provide information on the composition and characteristics of the mortar sample(s) received. Assuming that the sample was representative of the mortar, analysis provides a quantitative measure of aggregate grading, a semi quantitative estimate of binder: aggregate weight ratio, and a qualitative assessment of the binder type. This should provide a basis for specification a repair or replacement mortars

If more detailed information is required, for example for purposes of historic research, more sophisticated analytical procedures can be undertaken to determine sample chemistry and mineralogy – such as thin section analysis below.

Oolitic limestone

Sandstone

Historic Lime Mortar

We can also analysis sands that are currently available and can provide full specifications of repair mortars and plasters.