This paper extended the 2D meso-scale image-based models to 3D by using a small volume proportion of images obtained from an X-ray computed tomography test. The real microstructure of concrete specimen was characterized as three phases: aggregate, cement and voids (which is empty areas). Zero-thickness cohesive interface elements were embedded in cement phase to represent the potential cracks (no cracks allowed to propagate through aggregate particles). The average stress-strain curve of the 3D mesh under uniaxial tension was compared with a 2D simulation result. The crack propagation process in 3D was illustrated together with the final crack surfaces.