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

‘Wet walls’: developing non-destructive multi-sensor moisture monitoring methodologies for stone masonry

Saturday, October 14
10:45 AM - 12:15 PM

Historic buildings and engineering structures are at risk from increased frequency and severity of weather events and more extreme climate variability. Of specific concern are those containing materials such as brick, stone, mortar, and concrete. Due to their porous nature, most processes affecting their strength, appearance, and hygrothermal properties are caused—or supported—by water. Diagnosing the patterns and dynamics of moisture movement in situ is imperative to understanding how a building performs and relates to the environment, thus characterizing resilience to a changing climate and informing sustainable maintenance.

Current non-destructive technologies that infer moisture contents from physical properties cannot accurately identity levels of moisture at depth over time. This project addresses this gap through a multi-sensor approach to moisture monitoring, and is undertaken in collaboration with Historic Environment Scotland and the Consarc Design Group. Specifically, it employs microwave moisture sensors, infrared thermography, and high-frequency radar to monitor drying patterns of building façades and material samples. This research incorporates various streams:

1) Increasing survey accuracy and precision through multi-sensor data fusion: this approach capitalizes on the unique spatial scales and resolutions of different technologies while reducing the impact of noise and confounding factors on moisture surveying.
2) Microwave-based 3D tomography: a novel approach to assess the distribution of moisture in stone monoliths and small masonry systems. This is achieved by interpolating overlapping surface contact microwave moisture sensor measurements with different penetration depths, demonstrating that a homogenous assumption for gravimetric calibration is often inaccurate.
3) Near-surface moisture detection using high-resolution radar: identifying important features in radar trace scans that are sensitive to a range of surface moisture contents on stone masonry systems. This is an efficient method of surveying moisture and a unique approach to analyzing radar data that contrasts traditional use to investigate sub-surface features.
4) Past, present, and future risk to heritage due to wind-driven rain: a statistical analysis of long-term trends in driving rain spells in the United Kingdom. This research elucidates the changing face of weather-related risk to cultural heritage in the temperate UK climate.

Of specific interest is developing and trialing in situ techniques that adapt to complex building scenarios incorporating a range of materials: for example, the assessment of mortar performance in traditional masonry. A methodology is proposed to synthesise the output from radar and microwave moisture sensors to characterize mortar and masonry units behavior, respectively.

Developing robust moisture monitoring methodologies that can diagnose spatial and temporal patterns at various depths is a fundamental component of informing sustainability and resilience in the face of an uncertain and rapidly changing climate.

Learning Objectives:

Scott A. Orr, BASc, MRes, AMRSC, ASCHB

Doctoral student
University of Oxford

Scott Allan Orr AMRSC AMInstNDT GMICE is a doctoral student at the University of Oxford as part of the UK Centre for Doctoral Training in Science and Engineering in Arts, Heritage, and Archaeology (SEAHA). Scott holds a BASc in chemical and environmental engineering from the University of Toronto and an MRes from the Bartlett Faculty of the Built Environment at UCL in 2015. His research develops multi-sensor methodologies for monitoring moisture in collaboration with Historic Environment Scotland and the Consarc Design Group. Following his PhD, he hopes to continue research contributing to technological innovation and management of the historic built environment.

Presentation(s):

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