Statistical Design of Eco-Friendly Mortar Mixtures Containing Scheelite Tailings and Quartzite Sand: Evaluation of Resistance to Alkali-Aggregate Reaction

Abstract

This study focuses on addressing the challenge of society’s consumer demands through sustainable production processes, as outlined by Sustainable Development Goal 12 established by the United Nations. In this context, this study aims to assess the durability of eco-friendly mortars with mineral waste as alternative raw materials, considering the alkali-aggregate reaction (AAR). For this purpose, scheelite tailing (ST) was used to partially replace Portland cement (PC), and quartzite sand (QS) was used to fully replace conventional sand. The ST was ground and sieved (<75 μm), and part of it was used in its natural form, while the other part was calcined (1000 °C for 1 h). A mixture experimental design was created to select the compositions with the best mechanical performance. All the mortar mixtures were produced with a cementitious material to QS ratio of 1:3. Three mortar compositions (0% ST, 30% natural ST, and 30% calcined ST) were selected to study the resistance to the AAR. Linear expansion measurements, compressive strength tests, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy were conducted to evaluate the phases formed and the mechanical behavior of the mortars in relation to the AAR. The expansion results demonstrated that QS does not exhibit deleterious potential. Regarding the use of ST, the results indicated that it is possible to partially replace PC with calcined ST without significantly compromising the mechanical performance and durability of the mortars. However, the use of non-calcined ST is not recommended, as it presents deleterious effects on the mechanical properties of the mortars. This study highlights a new sustainable mortar alternative for use in construction without future degradation of its properties.