White Paper

Digital Image Correlation (DIC) is a technique which can deliver video footage of the strain development on the surface of a material due to loading or other actions. 

Lucideon has recently used the technique on concrete masonry for the first time with some extraordinary results. This paper describes the technique and how it was used on two projects. 

The first project was to study the strain development in masonry walls made from Autoclaved Aerated Concrete (AAC) and dense aggregate concrete and subjected to a single concentrated load. The results illustrate clearly that the material beneath the point of load application was the most heavily compressed and that the pressure is gradually dissipated from the point of load application with contours of equal principal compressive stress in ‘bulb’ shapes. On failure the heavily compressed zone beneath the loading plate effectively became “part of the loading plate” in a similar way as soil under a foundation. 

The second project studied walls made from storey-height panels of AAC, jointed vertically by mortar, and subjected to a concentrated vertical load. In this case, the load effects were transmitted across the vertical joint indicating that more than one panel resisted the load until just prior to failure, which was by the joint failing in shear. The results were used to improve design provisions for walls subjected to concentrated loads.