ABSTRACT
At the end of the curing period, specimens made with each type of concrete were divided into three groups: specimens of two groups, for each concrete, were pre-cracked in 3-point bending, up to (residual) crack openings equal to about 130 and 270 μm respectively, whereas specimens belonging to the third group were left uncracked. Specimens were then put into a climate chamber and subjected to the temperature and humidity cycle sketched in Figure 1. Specimens were kept into the climate chamber for four weeks. At the end of the first and
2 EXPERIMENTAL RESULTS
Figure 2a shows an example of Load vs. COD curve, as recorded from the same specimen tested in 3-point bending before and after the climate chamber exposure. The latter curve has to be interpreted as a reloading of the specimen, following a previous unloading at a prescribed crack opening and the hygrothermal conditioning. The post-conditioning load-COD curve has been rigidly shifted backward along the axis of abscissae (Figure 2b), until its peak load point intersected the softening branch of the virgin load-COD curve. The amount of this shifting was defined as Recovery Index or Index of Crack Self-Healing (ICSH) (Figure 3a-b).
