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

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.