Material asfáltico fresado estabilizado com ligante álcali-ativado alternativo: desempenho mecânico, microestrutural, durabilidade e lixiviação

Abstract

From a social and environmental perspective, the use of industrial and construction waste is an alternative for the preservation and reuse of natural resources. In paving, the use of milled asphalt material (RAP) in pavement recycling is an alternative for the structural and functional recovery of the highway. Despite the technical, economic and environmental advantages of the method, RAP often needs to be stabilized by some material with cementing properties, usually Portland cement. However, due to the high levels of CO2 emitted during its production, alkali-activated materials are an alternative for replacing traditional cementitious materials. The alkali-activation process consists of mixing an aluminosilicate mineral (precursor) and a highly alkaline solution (activator). One of the most widely used activators is sodium silicate, which despite its good performance also has a production process with significant carbon dioxide emissions. In this sense, rice husk ash (RHA) is a silica-rich waste with potential for the development of alternative activators. Thus, the objective of this research is to evaluate the technical feasibility of an alkali-activated system of RHA, metakaolin and sodium hydroxide in the deep recycling of pavements. To achieve this objective, a parametric study of the production of an alternative alkali activated binder (AAL) was initially carried out in order to reduce the environmental and energy impact of the binder. Subsequently, various proportions of RAP and AAL were evaluated in terms of mechanical and microstructural performance, durability, long-term performance, alkali leaching and fatigue degradation. The results demonstrated that AAL is a suitable option for use in RAP recycling. From an environmental point of view, the results of this study show that the technique brings positive perspectives, together with innovative technologies, for the development of sustainable pavements.