The use of graphene nanoplatelets for enhancement of the compressive strength of mortar containing high-levels of natural Pozzolan

Abstract

High Pozzolan concrete has an extended setting time and inhibits early-age compressive strength development, which can cause construction delays and limit its application in the concrete industry. The main aim of this study is to evaluate the effectiveness of graphene nanoplatelets (GNPs) in enhancing the mechanical properties of mortar containing high levels of natural Pozzolan. In the beginning, a relatively simple ultrasonication treatment process produced an almost uniform dispersion of GNPs in the mixing water to avoid agglomeration which limits the efficiency of GNPs. Tests on engineering properties indicated that the compressive strength of mortar containing 40 and 60 % natural Pozzolan as a partial replacement of cement was enhanced with the addition of the optimum content of graphene nanoplatelets which was found to be 0.03 % and 0.01 % by weight of binder at 40 % and 60 % cement replacement levels, respectively. The compressive strength was enhanced by 29.6 %, 27.4 %, and 27.5 % at 40 % cement replacement level, and by 86.3 %, 23.7 %, and 25.8 % at 60 % cement replacement level at 7, 28, and 56 days of curing, respectively. SEM investigations indicated that the addition of GNPs densified the structure thus enhancing the performance of mortar.