Development of high-strength geopolymers from red mud and blast furnace slag

The worldwide growing interest in green construction urges for innovation of building materials by reusing the existing waste resources, especially industrial by-products like red mud, which has been an environmental concern in the last few decades. This paper presents a study that investigated the potential use of red mud as a raw material in the development of high-strength geopolymers. A Sodium hydroxide (NaOH) and Sodium silicate (Na2SiO3) solution were used as the activation reagent for red mud, and blast furnace slag-derived geopolymers. This study adopted two different mixing procedures while activating the raw ingredients. Additionally, Ten percent (10%) by weight silica fume was introduced as an additive to assess its impact on the formed geopolymers. The mechanical and microstructural properties of the geopolymers were characterized based on two types of preparation processes. The synthesized geopolymers achieved extraordinary early compressive strength as high as 68.8 MPa. A high proportion of red mud, 50 percent by weight, could be utilized as a raw ingredient achieving a high strength of 66 MPa. The optimum initial molar ratios were reported based on the geopolymer products' compressive strength and microstructural performances. Silica fume was found to be an efficient additive that enhanced overall performance, ensuring higher proportional use of red mud as a raw material.