Sustainable Mortars Incorporating Industrial Rolling Mill Residues: Microstructural, Physical, and Chemical Characteristics

New alternatives in the construction industry are essential for economic, sustainable, and environmental progress. In this context, this work investigated three sets of sustainable mortars incorporating industrial lamination waste, assessing their chemical, physical, microstructural, and mechanical properties to inform their development. Cylindrical and prismatic specimens were produced using the following incorporation methods: a reference mortar, mortars with mill scale addition, partial cement replacement with mill scale, and partial sand replacement with mill scale, at proportions of 10%, 20%, 30%, 40%, and 50%. Additionally, analyses including X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) were performed. Physical and mechanical tests, including bulk density, consistency index, capillary water absorption, axial compressive strength, and flexural tensile strength, were also conducted. XRF results indicated an increase in iron oxide content and a decrease in calcium oxide with the addition of mill scale. XRD confirmed the presence of compounds, such as alite and portlandite, which are common in cementitious mortars. FTIR spectra exhibited characteristic functional groups through absorption bands related to Si–O stretching. SEM micrographs revealed slight morphological changes in the composites as the quantity of industrial lamination waste increased, and EDS data supported the XRF findings. The addition of industrial lamination waste affected the spread index and density of the mixtures, while capillary water absorption decreased in some formulations with mill scale. The strength of the mortars increased with the incorporation of industrial lamination waste. In conclusion, using industrial lamination waste in mortars is a technically and environmentally feasible alternative that aligns with the principles of sustainable development and the circular economy in the construction industry.