Lime–Ground Glass–Sodium Hydroxide as an Enhanced Sustainable Binder Stabilizing Silica Sand
Nilo César Consoli, Cocou Auxence Pierre Daassi-Gli, Cesar Alberto Ruver, Andres Lotero, Hugo Carlos Scheuermann Filho, Cindy Johanna Moncaleano, David Eduardo Lourenço
Abstract
Ordinary portland cement (OPC) has been extensively used for decades to improve the engineering properties of a variety of soils. However, the environmental issues related to the production of OPC have created an urgent need to develop and use alternative binders such as alkali-activated cements (AAC). Thus, this work assesses the mechanical performance of a sandy soil amended with an AAC composed of ground waste glass (GWG), carbide lime (CL), and sodium hydroxide (NaOH). The effect of key factors, such as the presence of a NaOH solution, the dry unit weight, and the amount of binder were evaluated on the unconfined compressive strength (qu), initial shear modulus (G0), and accumulated loss of mass (ALM) of compacted sand-binder specimens cured for 7 days. When analyzing the curves that correlated the mechanical behavior of the blends (qu, G0, and ALM) with the η/Biv index, the results show that the alkaline solution has a significant positive influence on the mechanical response of the tested specimens. The improved mechanical performance of the alkali-activated treatments was associated with the formation of a blend of C─ S─ H and (C,N)─ S─ H cementitious compounds coexisting in the same cementitious matrix (alkaline hybrid cement), of heterogeneous structure and composition, and characterized by developing in greater quantity than those produced from a pozzolanic reaction.