Mechanical, Thermal Stability, and Shielding Properties of Slag/Granite Geopolymer Cement Modified by Nanoparticles

In this study, we developed alkali-activated geopolymer cement (GP) using finely powdered granite waste (GW), blast furnace slag (BFS), and nano-silica (NS). NaOH and Na 2 Si 2 O 3 (1:1) were used as an alkaline activator to activate the GP mix and promote the alkali-activation reactions. The mechanical properties of various GP mixes were analyzed to evaluate the durability of the resulting GP when subjected to firing at temperatures up to 750°C and the destructive effects of gamma-ray irradiation. The study revealed that blending up to 30% granite powder to the GP formulation led to faster setting due to the excess soluble Si ions sourced from the granite powder which accelerated the alkali-activation reactions and increased the stiffness of the pastes. Additionally, blending the GP mix by 10 % GW improved the compression resistance by 7 to 10 % during the later curing ages. Besides, these blended mixes have thermal stability behaviors against firing up to 750°C and irradiation by gamma rays. This is related to the thermal stability and heat storage capability of GW. Amelioration of BFS/GW mix by up to 2% NS greatly improves the compression resistance at all the stages of the alkali-activation process. Furthermore, the mixes reinforced by NS exhibited better durability in the two types of deterioration studied. This is attributed to the thermal stability of GW and the filling and/or catalytic actions of the dispersed nanoparticles through GP matrix. These factors strengthen the geopolymer network, enabling it to withstand the deteriorating effects of these harsh environments.