This Technical Advice Note, Scottish Aggregates for Building Conservation’, is based on a survey of Scottish aggregates, carried out in 1996, 1997 and 1998. It forms part of an occasional Series of advisory notes related to practical and technical issues which can arise in protecting the nation’s built heritage, and is intended to allow informed comparison and choice between a range of materials considered suitable for use as aggregates in traditional lime mortars. In this context the term aggregates includes naturally occurring sands and gravels and crushed rock products.

This publication can be used as a stand-alone guide to the selection of aggregates or in conjunction with the comprehensive range of ‘sand profiles’ of Scottish aggregates, and supporting data held on the associated database of Scottish Aggregates.

The distinctive local and regional characteristics of Scottish buildings depend not only on the type of stone employed in their construction, as ably described in Historic Scotland Technical Advice Note 12 ‘Quarries of Scotland’, but also on the nature of the mortars. The constituent materials of those mortars influence, in turn, the techniques of their use, their durability and their appearance as they mature and weather. Information on lime mortars generally is available in Historic Scotland Technical Advice Note I, ‘Preparation and Use of Lime Mortars’.

The information concerning aggregates for lime mortars in this Technical Advice Note, and in the database, is concerned with the appearance and other physical characteristics of the products, the matching of modern materials to those used in the past and the selection of aggregates with suitable physical characteristics for use in traditional lime mortars.

INGVAL MAXWELL Director, TCRE