# Reactive Powder Concrete: Durability and Applications
## 3 Results and Discussion  
Figure 1 compares the mercury intrusion porosimetry (MIP) results of a normal concrete, C30, a high strength concrete, C80, with the reactive powder concrete [4; 5; 6; 7; 8]. These results confirm and emphasize the extremely low porosity of RPC200 with absence of capillary pores. The mercury intrusion porosimetry (MIP) results are in agreement with the microstructural study performed by [PERSON] et al. [13]. They found that the microstructure depends on the heat treatment and applied pressure, which was applied before and during the setting time. The pozzolanic reaction was enhanced by the temperature. Determination and evaluation of the air permeability coefficient was performed by using the permeability method described in [33]. Concretes were conditioned by heating for 5 days at 50 \({}^{\circ}\)C or 30 days at 80 \({}^{\circ}\)C. Table 4 shows that RPC200 presents an air permeability coefficient 48 times lower than that of C80 when the treatment was curing at 80 \({}^{\circ}\)C for 30 days. However, the air did not flow through the RPC200 when the curing was at 50 \({}^{\circ}\)C for 5 days. In addition to these tests, resistance to chloride ingress was studied. In Figure 2, the chloride profiles from a natural diffusion test using a NaCl solution of 0.5% in chloride ion (around 30 g/L NaCl) are given. The values of the apparent diffusion coefficient (D\({}_{\text{ap}}\)) calculated from them, are given in Table 5.  
The results for the RPC were not conclusive (or were misleading) due to the small chloride entrance (concentration between 0.1% and 0.03% by sample weight, which are in the range of the chloride concentration in the raw materials). Consequently, accelerated tests were used by the application of an electrical field, and were made in order to have results in a reasonable short time. Table 5 shows the effective chloride diffusion coefficient (Def) (not considering binding) obtained by applying \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property** & \multicolumn{3}{c}{**Concrete Type**} \\ \cline{2-4}  & **C30** & **C80** & **RPC200** \\ \hline Air permeability coefficient (\(\times 10^{-18}\) m\({}^{2}\)): & & & \\
5 days curing at 50 \({}^{\circ}\)C & 30 & 0.3 & - \\
30 days curing at 80 \({}^{\circ}\)C & - & 120 & 2.5 \\ Porosity (\%vol) & 15 & 10 & 1 \\ Water absorption (kg/m\({}^{2}\)) & 2.7 & 0.3 & \textless{}0.2 \\ Carbonation rate (mm/y\({}^{0.5}\)) & 1.7 & 0.4 & \textless{}0.1 \\ Carbonation diffusion coefficient (\(\times 10^{8}\) m\({}^{2}\)/s) & 1.26 & 0.09 & \textless{}0.007 \\ Electrical impedance results: & & & \\ Corrosion potential (E\({}_{\text{corr}}\), mV \(<\)SCE\(>\)) & \(-0.82\) & +0.28 & +0.90 \\ Ohmic resistance (kOhm-cm\({}^{2}\)) & 0.37 & 12 & 3022 \\ Capacity (C\({}_{\text{HF}}\), pF/cm\({}^{2}\)) & 10,793 & 145 & 14 \\ Corrosion rate (\(\mu\)m/year) & 1.2 & 0.25 & +0.01 \\ Resistivity (kOhm-cm) & 16 & 96 & 1133 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Durability of the reactive powder concrete compared with normal and high strength concrete [3; 4; 5; 6; 7; 8; 9]. Figure 1: MIP cumulative porosity curves showing the curve corresponding to the reactive powder concrete in comparison with two curves for the C30 and C80 concretes. Figure 2: Chloride penetration profile in C30, C80, and RPC200 concrete. a potential difference of 12 V between the two parallel faces of a concrete disc of 5 mm [4] in thickness. In both cases, the diffusion velocity is two orders of magnitude smaller in the case of BPR concretes. For the calculation, the measured effective chloride diffusion coefficient was taken into account, which was higher than the apparent chloride diffusion coefficient. This is a conservative way of estimating the service life. Consequently, a reinforcement cover of 10 mm of RPC200 is enough to ensure a service life longer than 80 years in comparison to the five years for C80 with the same cover [4; 5; 6; 7; 8]. The carbonation rate of RPC was also calculated from accelerated tests.