Application of Digital Image Correlation (DIC) Method for Concrete Masonry Prism Testing

Concrete masonry units (CMUs) with knock-out webs are used in masonry construction to accommodate the horizontal reinforcement that provides structural integrity to the elements. Their use reduces structural self-weight, transportation costs, and potentially minimizes workplace injuries. However, the impact of using knock-out web units on the strength of masonry members and resulting failure modes has not been investigated. An experimental program was therefore conducted to investigate the load-resisting mechanism and failure behavior of masonry members constructed using knock-out web units. Accurate measurements of surface deformations and cracking patterns were therefore required. Conventional point-to-point strain measurement methods do not provide adequately detailed information on surface deformations and so cannot be used to describe the behavior of masonry members constructed using knock-out web units. It is also challenging to obtain consistent results using these conventional techniques as they are difficult and time consuming to set up, susceptible to human error, and can be damaged relatively easily. A full-field deformation measurement technique such as digital image correlation (DIC) is a non-contact method and was used to measure the detailed surface deformation and crack patterns of prisms subjected to concentric axial compression. A total of 42 three-course tall prisms were constructed in running bond with face shell mortar bedding in accordance with the provisions in CAN/CSA S304-19. The experimental investigation is ongoing and the results described in this paper suggest that the crack patterns at failure varied with CMU web height.