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Fig. 25.1 Test arrangement for self-healing experiments on notched beams
Fig. 25.2 Experiment setup
25.2.2.2 Loading Conditions
As shown in Fig. 25.2, each specimen is subjected to three-point bending. The whole
loading process is divided into two parts. Firstly, the load increased monotonically
with a rate of 0.0002 mm/s until the CMOD reached 0.15 mm. After unloading,
healing agent (cyanoacrylate PC20) was injected into all tubes to the height as shown
in Fig. 25.1. Then the test was paused for different periods of time (1-h, 24-h and
3-days) before the reloading test. Secondly, after the specimen was healed, it was
loaded monotonically again with the same rate of 0.0002 mm/s until the CMOD
reached 0.30 mm.
25.3 Results and Discussion
As demonstrated in Fig. 25.3, the Load-CMOD curves for both control specimen
(grey colour) and 24 h self-healing (blue colour) specimen are shown through the
whole testing process (including the initial loading and reloading stages). According
to the fracture theory for concrete [3], the crack propagation stages is highlighted
(marked with Roman numerals in Fig. 25.3).