*3.4. Chloride Resistance Test*

This test aimed to determine the effects of the bentonite addition on chloride transport in the mortar matrix and the chloride ion threshold at which the reinforcing steel began to corrode. Figure 9 shows corrosion potential and corrosion rate from time 0 until an abrupt change in tendency in the respective curves denoted the onset of reinforcement depassivation.

**Figure 9.** (**a**) Corrosion potential (0 to 100 h) and (**b**) corrosion rate (0 to 120 h), illustrating the abrupt change in tendency that denotes the onset of reinforcement depassivation.

The chloride diffusion coefficients calculated from the penetration depth of the colorimetric front depicted in Figure 10 are listed in Table 3. Much smaller values were observed for the mortar bearing 10% bentonite. Rather than penetration depth per se (the red line in Figure 10), the decline reflects differences in test times, for depassivation occurred in the reference earlier than in the bentonite-bearing material. In other words, it took much longer to reach the penetration shown in the figures in the bentonite-bearing than in the reference specimens, denoting higher electrical resistivity in the former.

**Figure 10.** Chloride penetration front upon finalization of the experiment with the detection of the onset of corrosion.


**Table 3.** Chloride non-steady-state non steady-state diffusion coefficient (Dns) in reference (OPC) specimens and samples bearing 10% bentonite (Be10).

Further to the chloride content data given in Table 4, surface concentration was higher, whilst the chloride threshold was, inversely, lower, in the presence of bentonite. This allows one to confirm that it is the transport phase expressed in the diffusion coefficient which controls the better behaviour of the mortar with bentonite.

**Table 4.** Concentration of chlorides in the surface of the specimen at the end of the experiment and in the surface of the steel bar.

