## 2 Experimental Investigation
### Measurement Techniques  
Electrochemical measurements were performed with an AUTOLAB/PGSTAT302N potentiostat (Version 4.9 AUTO83745, ECO CHEMIE, Utrech, Netherland, 2008) [34]. The central steel bar was used as the working electrode while the parallel bars on the sides were used as the counter electrodes. For the electrochemical measurements a silver/silver chloride reference electrode was used (SSCE; +0.222 V SHE). During the measurements a damp flannel was placed on the mortar surface in order to improve electrolytic contact between the mortar and reference electrode (Figure 2).  
Figure 1: Geometrical characteristics of the specimens and specimens corresponding to the MCC dosages.  
All the electrochemical measurements were associated with the humidity content of the test specimens, which were gradually moistening and were kept in a humidity chamber.  
The use of the potentiostat enabled the evolution of the corrosion to be studied by means of the polarization curve, producing data on the open circuit corrosion potential (E\({}_{\text{corr}}\)), and through the polarization resistance on the corrosion rate (i\({}_{\text{corr}}\)). Since midway through the 20 th century the polarization resistance technique has become a common technique to study corrosion [35].  
The first evaluation of rebar behavior with regard to corrosion was made by measuring their corrosion potentials, which are useful for a qualitative determination of whether the steel bars are in an active or a passive state. The data obtained were interpreted according to the ASTM C 876 standard [36], from which, taking into account the reference electrode used, it was concluded that E\({}_{\text{corr}}<-231\) mV would indicate a 90% probability that corrosion exists in the active state, a potential in the region \(-231\) mV < E\({}_{\text{corr}}<-91\) mV would indicate uncertainty, and E\({}_{\text{corr}}>-91\) mV would indicate a probability of 10% that corrosion exists in the active state.  
The following step was to interpret the results for the rate or intensity of corrosion as this information enables us to quantitatively interpret the active or passive state of the bars.  
According to different research [37], i\({}_{\text{corr}}<0.1\) uA/cm\({}^{2}\) indicates a passive state, 0.1 uA/cm\({}^{2}<\) i\({}_{\text{corr}}<0.5\) uA/cm\({}^{2}\) is equivalent to a low level of corrosion, 0.5 uA/cm\({}^{2}<\) i\({}_{\text{corr}}<1\) uA/cm\({}^{2}\) to a high level of corrosion, and i\({}_{\text{corr}}>1\) uA/cm\({}^{2}\) to a very high level of corrosion.  
The central bar was connected to a POWER SUPPLY FAC-662B (PROMAX, Barcelona, Spain, 1998) to accelerate the corrosion process in both the standard test specimens and the test specimens with LFS, for specimens containing 1.2% and 2% of mixed-in chloride ions by weight of cement, making the embedded central steel bar act as an anode. On the upper face of the test specimens was placed a damp flannel with a lead sheet on top; this acted as a continuous counter electrode [38]. The voltage necessary to maintain the intensity of the preset current (1.3 mA) was then measured, moistening the test specimens frequently, as the potential varies substantially with the humidity content (Figure 2).