Using Short-wave Infrared Range Spectrometry Data to Determine Brick Characteristics

ABSTRACT

Characterizing material strength in-situ for existing structures poses a major problem for a range of civil engineering applications including structural modelling for tunnelling-vulnerability assessment and pre-earthquake resiliency evaluation, especially for unreinforced masonry buildings. Present methods require expensive testing equipment often requiring access to the structure and possible destruction of historic material. This article introduces spectrometry as a non-destructive means for identifying different brick clays and their firing levels, both of which influence the masonry’s mechanical behavior. The experiments herein considered bricks of 2 clay groups (red and yellow) fired at 3 kiln temperatures (700ºC, 950ºC, 1,060ºC). Samples were examined via spectrometry within the short-wave infrared range (1,300–2,200 nm). A Partial Least Square Discriminant Analysis (PLSDA) model was calibrated using 96 samples and tested on a set of 48 samples, resulting in a 98% success rate in classification of the two clay types and a 100% success rate for classification among the 3 firing levels. The ability of the PLSDA model to reliably distinguish well-fired bricks from other samples, irrespective of raw material configuration, shows the potential to use this approach as a new, non-destructive means for in-situ assessment of brick for architectural conservation, as well as for safety and serviceability assessments.

KEYWORDS:

• Architectural conservation
• firing temperature
• masonry
• non-destructive technique
• short-wave infrared
• spectrometry
• SWIR

Acknowledgments

The authors wish to thank Dr. Hugh Byrne and Mr. Luke O’Neill (Dublin Institute of Technology), Mr. Mike Duhan and Mrs. Sinead Glynn (National College of Art and Design), Mr. Derek Holmes and Mr. John Ryan (University College Dublin), and Mr. Bert Neyens (Vandersanden Group) for their support and assistance in conducting the experimental parts of the study. The authors have no conflicts of interest to disclose.

Additional information

Funding

This work was supported by the FP7 Ideas: European Research Council [ERC-2013-StG call—Proposal No. 335508—BioWater]; New York University Center for Urban Science + Progress.