_Article_  
**Temperature Impact on the Assessment of Reinforcement Corrosion Risk in Concrete by Galvanostatic Pulse Method**  
**[PERSON] \({}^{\text{\textregistered}}\)\({  
in favourable conditions, when the passive layer protecting the bar surface is damaged (usually as a result of concrete carbonation or action of chlorides), the pores are filled with liquid, and oxygen is available. The iron oxidation process occurs at the anode:  
\[2\text{Fe}\to 2\text{Fe}^{2+}+4\text{e}^{-}\]  
and the reduction process occurs at the cathode:  
\[2\text{H}_{2}\text{O}+\text{O}_{2}+4\text{e}^{-}\to 4\text{OH}^{-}.\]  
Figure 1 schematically this. In the course of the corrosion process, iron ions react with OH\({}^{-}\); ions, forming iron hydroxide:  
\[\text{Fe}^{2+}+2\text{OH}^{-}\to\text{Fe(OH)}_{2}\]  
and then in the presence of oxygen:  
\[2\text{Fe(OH)}_{2}+1/2\text{O}_{2}\to 2\text{FeOOH}+\text{H}_{2}\text{O}.\]  
As a result of the process, iron hydroxide is formed Fe(OH)\({}_{3}\) and iron oxide Fe\({}_{2}\)O\({}_{3}\) are produced. The corrosion product, rust, is a mixture of Fe(OH)\({}_{3}\), Fe\({}_{2}\)O\({}_{3}\), Fe\({}_{2}\)O\({}_{3}\), H\({}_{2}\)O, and magnetite [2; 6; 13; 14]. The degree of reinforcing bar corrosion can be determined from Equation (1) by calculating the corrosion loss that is based on [PERSON]'s law:  
\[\Delta\text{m}=\text{k}\times\text{i}\times\text{t} \tag{1}\]  
where:  
\(\Delta\text{m}\)-loss of weight [g],  
\(\text{K}\)-electrochemical equivalent [g/A \(\times\) s]  
\(\text{i}\)-corrosive current strength [A], and  
\(\text{t}\)-current flow time [s]. The corrosive current can be determined from Equation (2):  
\[i=\frac{\Delta\text{E}}{R_{K}+R_{A}+R_{O}+R_{Z}} \tag{2}\]  
where:  
\(\Delta\text{E}\)-anode and cathode potential difference,  
\(\text{R}_{K}\), \(\text{R}_{A}\)-cathode and anode polarization resistance, and  
\(\text{R}_{O}\), \(\text{R}_{Z}\)-internal and external circuit resistance. Figure 1: Reinforcement corrosion process in concrete. Equation (2) indicates that the moisture level-dependent internal resistance that inhibits ion transport is important. The diffusion is practically stopped at the moisture content below 75%. The temperature of the tested element also affects the ion diffusion coefficient [2; 13]. The diffusion coefficient increases with the increase in temperature (the increase rate depends on the concrete composition), as shown by the Arrhenius equation:  
\[D=D_{0}e^{-\frac{E}{kT}} \tag{3}\]  
where:  
D-diffusion coefficient at temperature T [cm\({}^{2}\)/s],  
D\({}_{0}\)-diffusion coefficient at temperature T = 0,  
E-activation energy of the diffusion process [KJ/mol] (dependent on w/c and type of cement),  
R-gas constant (R = 8.3144598(48) [J/mol \(\times\) K]), and  
T-absolute temperature [K]. As a result of the electrochemical process of reinforcement corrosion in concrete, certain electrical quantities change. Stationary potential, concrete resistivity, or corrosion current density can be measured and used for the estimation of the extent of reinforcement corrosion. Measurements are made while using specialized devices and the results are analyzed against the criteria values pre-determined for a given device [6; 12; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32]  
The galvanostatic pulse method (GPM) is one of the methods used for this purpose [21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32]. It is a non-destructive polarization technique that allows for measurements of the reinforcement stationary potential on the concrete surface (E\({}_{\text{st}}\)), concrete cover resistivity (\(\Theta\)), and corrosion current density (i\({}_{\text{cor}}\)). The measurements of the reinforcement stationary potential and the concrete cover resistivity are called basic measurements.