International RILEM Workshop on Historic Mortars: Characteristics and Tests Paisley, Scotland (1999)

The return to traditional materials and techniques, within present-day technical and economic circumstances, revealed large gaps in factual knowledge, which often relied on fragmented historical records and a lack of understanding of fundamental processes underlying good performance of existing historic and new "traditional" mortars. A very strong demand has developed for an improved guidance for conservation practitioners, outlining good practice and underpinned by sound scientific and technical knowledge. Formation of the RILEM Technical Committee TC 167-COM on "Characterisation of old mortars with respect to their repair" in 1996 under the chairmanship of Dr Caspar Groot reflected this demand.

The Workshop differed substantially from other events in the built heritage field, which usually bring together only one of the several, often narrow sectors relevant to conservation. In Paisley, the participants reflected the great diversity and complex interdisciplinary activity, which prevails in the built heritage field. The event brought together art historians, conservation architects, custodians of historic buildings and monuments, structural engineers, geologists, material scientists, chemists and physicists, expert conservation craftsmen, specialist contractors and suppliers of mortar-related materials. Presentations, in a balanced manner, varied from applications of fundamental theory supported by atomic science and mathematical modelling to practical expertise in re-creation of ancient and traditional techniques and skills for production, handling of mortar and repair of historic masonry. The role of mortar was also rationally developed, from its the very beginning when dry-laid stone walls still prevailed in "pre-history" to sophisticated masonry, plasters and renders of recent centuries. There were vigorous discussions after each of the Sessions and the social events provided opportunities for further, more personal exchange of views and opinions. A review of the most significant contributions and conclusions stemming from the discussions is provided in the final chapter of this book.