## 4 Conclusions  
This paper analyzes the variation of the internal pore morphology of two different mixtures cured under two different curing conditions, through the use of a CT scanner and a DIP software. Some findings were obtained. First, it can be noticed that the steel-fiber-reinforced concrete specimens show a greater amount of pore volume than the plain concrete ones. This happens in both moist-cured and air-cured concrete. Two phenomena can explain this, both of them related to fresh concrete. First, fibers may trap and retain more pores during the concreting process. Second, the voids created due to the internal water-consumption process can be easily retained in the case of steel-fiber-reinforced concrete. In the case of steel-fiber-reinforced concrete, a higher porosity is observed in the interior of the specimen, i.e., far from the exposed surface, where the porosity is smaller. This phenomenon can be observed in both air-cured and moist-cured specimens. In the case of plain concrete, this phenomenon can also be observed, although it is less intense. In this case, no relevant differences between air-cured and moist-cured concretes have been detected. When both the pore volume curves and the porosimetric curves are studied, it can be observed that steel-fiber-reinforced concrete specimens are capable of retaining greater voids. This fact can be explained in terms of fresh concrete. Fibers provide additional stiffness to the fresh cement paste, allowing SFRC specimens to retain a greater number of large-size voids. Again, no relevant differences between air-cured and moist-cured concretes were detected. When the nominal maximum pore size (NMPS) was studied, it was revealed that steel-fiber-reinforced concrete specimens are able to have a higher value of NMPS than the one of plain concrete and, additionally, air-cured mixtures show a higher value of NMPS than the one of moist-cured mixtures. This means that curing conditions modify the pore-size distribution. When we studied how the pore volume curves and the porosimetric curves evolve along the depth, some interesting results were observed. First, the percentage of small pores increases with the depth. This happens in both mixtures and in both curing conditions. This variation is less intense in the case of steel-fiber-reinforced concrete than in plain concrete. Again, the rheology of fresh concrete seems to be behind these observations. The study of the shape factor reveals that voids are far away from a sphere; in fact, they are very flaky or elongated. This phenomenon can be observed in both mixtures and in both curing conditions. However, voids belonging to the steel-fiber-reinforced concrete specimens show a smaller shape factor. It can also be observed that there is a small variation of the shape factor with the depth, but in all the cases, a progressive increase of it can be observed. In terms of voids' orientation, it can be observed that, in all cases, the voids tend to be oriented horizontally, i.e., perpendicular to the vertical direction (which coincides with the concreting direction). In the horizontal plane, no dominant direction can be observed. In the case of steel-fiber-reinforced concrete specimens, the fibers' orientation is also obtained, and the results are similar to the ones observed with the voids: Fibers tend to be oriented perpendicularly to the vertical axis, and, in the horizontal plane, they are randomly oriented. The efficiency index is obtained for all the mixtures and all the curing conditions, for both the voids and the fibers (when it is possible, i.e., in the case of steel-fiber-reinforced concrete). The results demonstrate that fibers influence the voids' orientation. In this case, the curing conditions are less relevant, but not negligible.