Use of image correlation system to study the bond behavior of FRCM-concrete joints

This paper presents a non-contact measurement approach, based on digital photogrammetry, applied to the experimental study of the bond behavior of fiber reinforced cementitious matrix composite to concrete joints tested in single-lap direct shear tests. The use of digital photogrammetry techniques and traditional contact measurement approaches for determining displacement and strain are investigated and compared. The results show that measurements of strain in the fiber bundles determined using the image correlation system (ICS) correlate well with those obtained from electrical strain gauges. However, differences of 38-52% were observed between the maximum strain measured with either ICS or electrical strain gages attached to the fiber bundles and the maximum strain in the fiber bundles computed from the maximum applied load. ICS is also used to measure slip and strain of bare fiber bundles, and results show that the load distribution among fiber bundles is non-uniform. The proposed measurement approach shows higher spatial measurement resolution and increased accuracy compared to traditional contact approaches by enabling measurements in each fiber bundle and overcoming the need to attach additional elements to the tested specimen.