Track 1: DOCUMENTATION AND DIAGNOSTICS – UNDERSTANDING HISTORIC PLACES / Volet 1 : Documentation et diagnostic – Comprendre les lieux historiques

Comparing the Deterioration of Mortar Types Used on Parliament Hill, Ottawa - An Approach Based on Statistical Analysis.

Friday, October 13
10:30 AM - 12:15 PM

The durability of mortars is a key consideration in any rehabilitation project as an important part of conserving historic masonry. The mortar must be compatible with the historic masonry and able to withstand the extremes of the Canadian Climate.

In the process of preparing contract documents for the envelope conservation of the East Block, Parliament Hill, Ottawa it was confirmed that there have been numerous re-pointing campaigns, utilizing different mortar mixes at all of the buildings on Parliament Hill. Each generation of repairs embodied the prevailing conservation philosophies of the time. Some of these mortars have performed well whilst others have failed early. We wanted to establish a method to compare the in-situ performance of different mortar types and identify the ‘good’ mortars to inform the design of the mortar mix at the East Block taking all these variables into account.

A study was designed in collaboration with Heritage Conservation Services, PSPC for organizing, collecting and analyzing data related to the durability of the mortar types. The study was developed in two phases: the first phase involved developing the study parameters and a method for quantifying mortar deterioration and, to identify the tools required; the second phase was focused on data collection and analysis.

The different mortar types used on Parliament Hill were identified and organised into 2 main ‘families’ of mortars: 1) Cement, Hydrated Lime, Sand and 2) Hydraulic Lime, Sand mixes. Within these 2 broad categories different mortar recipes were identified. In total 8 different mortars were included in the study. A method was developed to review and compare the condition of the mortar types based on a set of pre-identified deterioration types and the use of HD photographs. The study size comprised 120 mortar locations/mortar panel/ photographs each reviewed by several raters who identified the mortar sections/length of each deterioration type.

The study considered the correlation between the measures of deterioration and explanatory variables (like exposure and age) between the various mortar types. The statistical analysis estimated the impact of each variable, after taking account the estimated impact of other variables and determined which effects were statistically significant; that is, strong enough given the sample size that they were unlikely to have occurred by chance.

The study was a worthwhile attempt to provide an objective review of in-situ mortar performance. However, as with any attempt at quantifying the effects of deterioration, which can be caused by any number of variables, there are things which could be refined and improved in further studies. The problems we encountered during the design and execution of this study and how future studies might benefit from our attempts at solving them comprise the central message of this presentation.

Learning Objectives:

Alex Brooks, BSc Architectural Technology, MSc Historic Conservation

Architectural Conservation Technologist
DFS Architecture and design

I obtained my BSc in Architectural Technology and MSc in Historic Conservation and have gone on to gain experience that comprises a range of diverse roles within architectural practices and heritage consultancies in the United Kingdom, Australia and Canada. My experience has involved many facets of the design and construction process, from heritage planning through to contract administration during construction. My current focus is on historic envelope rehabilitation, with an architectural practice specializing in the conservation of historic masonry buildings. I am interested in building and material science and how these technologies can be harnessed for use in heritage buildings.


Send Email for Alex Brooks

Stephen J. Kelley, FAIA, SE, FAPT, FUSICOMOS

Stephen J Kelley, Inc.

Stephen J. Kelley is a registered architect and structural engineer in private practice who has devoted these two skills to the preservation of our built cultural heritage. With 35 years of experience, his projects range from small to immense, simple to sophisticated and cover a wide range of building materials and systems. His award-winning projects are located throughout the United States but he has also worked on significant projects in Asia, Europe, Africa, South America and the Caribbean basin. He has published widely on various aspects of preservation and is an educator who has taught at the university level thus sharing his experience with the next generation of preservation professionals. He has served on the Board of Directors of both the US Committee of the International Council on Monuments and Sites (US/ICOMOS) and the Association for Preservation Technology (APT) and was elevated to Fellowship in both organizations. He is a UNESCO Tangible Heritage Expert and is Vice President of the International Scientific Committee on the Analysis and Restoration of Structures of Architectural Heritage (ISCARSAH).


Send Email for Stephen Kelley


Comparing the Deterioration of Mortar Types Used on Parliament Hill, Ottawa - An Approach Based on Statistical Analysis.

Attendees who have favorited this

Please enter your access key

The asset you are trying to access is locked. Please enter your access key to unlock.

Send Email for Comparing the Deterioration of Mortar Types Used on Parliament Hill, Ottawa - An Approach Based on Statistical Analysis.