## 4 Conclusions  
According to the results obtained in this study, the following conclusions can be drawn about the use of the studied admixture in concrete:  
* The incorporation of the admixture to the concrete allows the amount of mixing water to be slightly reduced for the same consistency. This makes it possible to improve the durability properties of the material or reduce the amount of plasticizing additive to be used in mixing (for the same consistency).
* The incorporation of the admixture is not detrimental regarding the compressive strength of Portland cement concrete.
* The admixture allows the generation of a more closed porous structure, and therefore less permeable, in Portland cement concrete. The reduction in porosity and water absorption is quantified at approximately 3% compared to a reference concrete.
* Portland cement concrete incorporating the admixture shows electrical resistivity values (in water saturated state of the pore network) that are approximately 10% higher than those of the reference concrete. This reflects a greater capacity to reduce porosity and permeability, especially in conditions close to water saturation of the pore network.
* Portland cement concrete incorporating the admixture has shown a slight reduction in the water absorption coefficient (water absorption test by [PERSON]'s method) in comparison to the reference concrete. This reduction is quantified at a value of 23% in the experimental conditions of this work.
* The unidirectional chloride diffusion tests have not revealed differences in behavior, in terms of resistance to chloride penetration by diffusion, between a concrete incorporating the admixture and a reference concrete.
* The incorporation of the admixture to Portland cement concrete has led to a considerable reduction in the air permeability coefficient (Torrent test) compared to a reference concrete. This reduction is quantified between 36% and 55%.
* The incorporation of the admixture can reduce the scatter in the corrosion initiation times of the steel reinforcements and could have an effect of delaying the onset of their corrosion, with respect to a reference concrete. Under the test conditions of the present research, the delay in corrosion onset times could translate into an increase from about 110 days to about 170 days. However, more experiments would be necessary, with a greater number of specimens and a longer duration of the tests, to be able to carefully evaluate the effect of the incorporation of the admixture on the corrosion processes of steel reinforcement in concrete.  
**Author Contributions:** Conceptualization, M.A.C.; methodology, C.A., H.G. and M.A.C.; software, G.d.V.; validation, C.A., H.G., and M.A.C.; formal analysis, C.A., G.d.V. and M.A.C.; investigation, C.A. and H.G.; resources, C.A. and M.A.C.; data curation, C.A., H.G. and G.d.V.; writing--original draft preparation, C.A., H.G. and G.d.V.; writing--review and editing, C.A., G.d.V. and M.A.C.; visualization, C.A., H.G. and G.d.V.; supervision, C.A. and M.A.C.; project administration, M.A.C.; funding acquisition, M.A.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Spanish Agencia Estatal de Investigacion (grant code BIA2016-80982-R) and by the European Regional Development Fund (grant code BIA2016-80982-R).  
Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
The authors thank the company producing the admixture, which provided the samples of the product used in this study under the agreement that neither the name of the product nor that of the company should be disclosed.  
Author [PERSON] was employed by the company AG Corrosion. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.