en Research Paper Research Paper In this work, the addition of a combination of Graphene Oxide Nanoplatelets (GONPs) and Ground<br> Granulated Blast Furnace Slag (GGBFS) was studied as admixture in concrete. Tests on physical and mechanical<br> properties and chloride permeability were conducted. GGBFS was replaced with Ordinary Portland Cement (OPC)<br> and it was determined that GGBFS Up to 50% by weight improves the physical and mechanical properties of<br> concrete. GONPs with an optimal amount of 50% by weight of GGBFS were added to the concrete and the physical<br> and mechanical properties of the samples were determined. It was observed that the addition of GONPs was effective<br> in improving the mechanical strength and physical properties of specimens. The results indicated that addition of<br> 0.1 wt.% GO and 50 wt.% GGBFS would increase the compressive strength of the concrete sample up to 42.7%<br> during 28 days and 46% during 90 days compared to OPC. Concrete with a combination of 0.1 wt.% GONPs and<br> 50 wt.% GGBFS witnessed an increase in its flexural strength up to 58.5% during 28 days and 59.2% during 90<br> days. The results indicated that by adding 0.1 wt.% GO and 50 wt.%, concrete chloride permeability decreased<br> substantially 72% for 90 day cured samples compared to OPC. GONPs as an alternative to cement up to 0.1% by<br> weight can accelerate the formation of C-S-H gel, thereby increasing the strength and improving the resistance of<br> water absorption and chloride permeability. The effects of pozolanic reaction in the concrete leading to the filling<br> of the pores were significant factors in the proposed curtailment mechanism Concrete, Durability, Graphene Oxide, Ground Granulated Blast Furnace Slag 1 22 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-4368-1&slc_lang=en&sid=1 Davar Rezakhani daavaar@gmail.com 1800319475328460016471 1800319475328460016471 No Materials Science and Engineering Dept., Shahid Bahonar University Abdol Hamid Jafari jafham2020@gmail.com 1800319475328460016472 1800319475328460016472 Yes Materials Science and Engineering Dept., Shahid Bahonar University