## 5 Conclusions  
To prevent a reduction in the durability of concrete due to the presence of water, powders to which water repellency was provided, were added to cement mortar and then the physical properties' and durability's performance were examined.  
It was found that the water repellent impregnated natural zeolite (ZWR) specimen exhibited lower flow and air content values compared to other specimens, and its compressive strength was 83% of that of the reference mortar. It appears that ZWR reduced pores and served as a cushion. Therefore, the strength was slightly reduced.  
In the contact angle test, the results of exceeding the hydrophobicity criterion of 90\({}^{\circ}\) were obtained in order of WR-In (130\({}^{\circ}\)) > ZWR (124\({}^{\circ}\)). It appears that the particles of the water-repellent's active ingredient in the water-repellent powders were attached to the pores in concrete and the repulsive force was generated by the surface tension of the pores.  
In the water penetration test, all the specimens except for ZWR exhibited low water penetration resistance at an atmospheric pressure of 0.3 N/mm\({}^{2}\). This appears to be because the water-repellent active ingredient filled the pores, which serve as transport pathways for water, without being separated.  
In the resistance chloride ion penetration test (RCPT), ZWR exhibited the low total passing charge, which was approximately 30% of that of ordinary Portland cement (OPC). It was confirmed that ZWR was also resistant to the penetration of chloride ions, which can be generated by the penetration of water.  
The mercury intrusion porosimetry (MIP) results showed that the distribution and size of pores in ZWR were almost similar to those in the reference mortar.  
The water-repellent's active ingredient can induce the separation of substances from cement as a different substance, but it can provide water-repellent performance by filling the pores in cement if fixed using a carrier and not discharged. In the case of fly ash (FA) and silica fume (SF), however, their smooth and spherical surface makes it difficult for them to serve as carriers, and it appears that the discharged water-repellent's active ingredient affects the initial bonding and hydration reaction. It was  
Figure 16: Curing at 28 days and the electron scanning microscope analysis.  
confirmed that all unreacted particles except for the particles involved in ionic reactions are factors that inhibit reactions, and that they may cause problems with compressive strength and absorptivity.  
To provide water-repellent's performance to concrete using a carrier, the ability of the carrier to fix the water-repellent active ingredient is important. It is also important to improve the pore structure as the porosity and pore size are reduced by the water-repellent active ingredient. In the scope of this study, natural zeolite appears to be the most ideal carrier for providing water-repellent performance.  
[PERSON] designed the work, performed the experiments, analyzed the data and wrote the initial draft of the manuscript. [PERSON] was involved in the scientific discussion, revision and finalizing the manuscript as well as in funding acquisition. All authors have read and agreed to the published version of the manuscript.  
This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2015R1A5A1037548).  
The authors declare no conflict of interest.