Bauxite residue (BR), a by-product of alumina and aluminum production, consists of high aluminum, silica, and iron content, and sodium from the bauxite ore digestion during the Bayer process. This waste is still being disposal into the lakes of mud, causing some environmental problems. So, the search for its application has gained interest. Studies reported in literature point out that one of the most promising applications is in association with Portland cement, which can also help to reduce the environmental impact caused by the CO2-emissions in its production. In this work, a combined evaluation of oscillatory rheometry and isothermal calorimetry was performed for the monitoring of the hardening stage of Portland cement (PC) compositions blended with BR generated in different sites in Brazil. The time-sweep test was applied to obtain the consistency gain of suspensions over-time, allowing us to understand the physical parameters of consolidation, while the changes in the hydration reaction showed considerable differences in the chemical contribution. As a conclusion, it was clear the impact of each BR, mainly due to the aspects related to soluble aluminates, silicates, and sodium, which in association with the soluble ions from PC, affected the chemical reaction and agglomeration/flocculation forces of particles.

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Grout is a material usually applied to enhance the mechanical properties of structural masonry. As such, the demand for grout has been growing parallel to the demand for structural masonry. Without guidelines for grout mixing design, these products are often prepared on-site based on the same concepts used for preparing ordinary Portland cement-based concretes. Several grout properties still need to be investigated and understood due to this mixing-design approach, and consequently, the production of ecoefficient grouts is a secondary priority. Due to these obstacles, there is a demand for technical-scientific studies to aid with developing grout design guidelines. This work evaluates the rheological and hardened properties of grout compositions that simulate in-field conditions to show the inadequacy of the mixing design method and a way to understand this lack in the technology. The research investigates how the changes in the water-to-cement ratio, to increase the strength, would affect the fresh and hardened state properties of grouts for structural masonry. The grout’s mixing was done in a rheometer which made it possible to determine the rheological behaviour and parameters during mixing and under different shear conditions. Compressive strength, porosity, and air-permeability were evaluated in the hardened state. The results showed that compositions with more cement content does not necessarily reflect enhanced mechanical properties since the differences were not statistically significant, because other variables were also changed. The research findings suggest that the design method used in practice may not be appropriate and potentially result in the waste of cementitious materials and no-eco-friendly compositions.