Constituent material properties of New Zealand unreinforced stone masonry buildings

Most of New Zealand’s stone unreinforced masonry (URM) building stock was constructed between 1860 and 1910 by early European settlers, with approximately 670 stone URM buildings remaining throughout the country. These buildings are typically classified as earthquake-prone, indicating that they require seismic strengthening in order to avoid demolition as a seismic hazard. Practitioners and industry professionals currently lack knowledge about the traditional construction techniques used for these buildings, and about suitable methods for improving their seismic performance. To address this knowledge gap, research was conducted to classify the constituent materials used in the original construction and to document the mechanical and physical characteristics of these construction materials. Extraction of structural mortar and natural stone samples was undertaken in buildings that were deemed to be representative of the New Zealand stone URM building stock, and X-Ray Powder Diffraction (XRPD) and petrographical analyses were performed on these samples respectively in order to identify mineral composition and their original source location. In addition, the compressive strength of extracted material samples was determined. A database of New Zealand natural stones that were typically used by the early European settlers in construction, including the source and compressive strength of each stone sub-type, is summarised herein. The presented data is intended to facilitate the selection of compatible materials and suitable techniques for repair and seismic retrofit of vintage stone URM buildings.