215295.fig.0013a
(a)
215295.fig.0013b
(b)
215295.fig.0013c
(c)
Figure 13: Cropped images (  pixels) of concrete cracks at different times, from (a) to (c), denoted by , and . By synchronizing with the loading time, seconds, seconds, and seconds (these time stamps are different from the relative ones used in Figure 10.