Produção de cimento álcali-ativado à base de escórias siderúrgicas a partir de sistema monocomponente (one-part)

Abstract

Alkali-activated materials (AAM) are a sustainable alternative to conventional cementitious binders, due to the reduction in 𝐶𝑂2 emissions associated with clinker production and the reuse of industrial by-products. However, conventional alkaline activators, such as hydroxide and sodium silicate, are costly, have a high carbon footprint, and pose handling risks, factors that drive the search for safer and more practical activators. In this context, one-part alkali-activated systems are a promising alternative, as they use solid activators dry-mixed with precursors, requiring only the addition of water. Therefore, the present research aims to obtain singlecomponent alkali-activated cements based on granulated blast furnace slag (EGAF) and BOF (Basic Oxygen Furnace) steel slag, widely available by-products of the steel industry, using solid alkaline activators. The slags underwent characterization and processing steps until powdered materials were obtained. Four pastes were produced with variations in EGAF and BOF slag contents, keeping the activator contents constant. In the fresh state, Kantro mini slump, apparent specific mass, and setting time tests were performed. In the hardened state, compressive strength and water absorption tests were conducted. The microstructure was verified by scanning electron microscopy (SEM), thermogravimetry (TGA), and isothermal calorimetry. The main results indicated that the paste with 70% granulated blast furnace slag and 30% BOF slag had the largest spread diameter of 71.63 mm, compressive strength at 28 days of 47.98 MPa, and satisfactory setting times, values compatible with practical and structural applications. Microstructural analyses confirmed the predominant formation of C-AS-H (calcium aluminate hydrate) gels, and the increase in the incorporation content of granulated blast furnace slag contributes to the acceleration of the reaction kinetics. Thus, the technical feasibility of using solid alkaline activators in single-component alkali-activated cements is confirmed.