Mechanical and thermal behavior of cement mortars incorporating fines from ornamental stone

ABSTRACT This study evaluated the influence of mix proportion and water/cement ratio on the mechanical and thermal performance of cement rendering mortars incorporating fines from ornamental stone processing (Fibro) as partial replacement of natural sand. A full 32 factorial design was adopted using three mix proportions (1:1:5, 1:1:6, and 1:1:7—cement:Fibro by mass) and three water/cement ratios (1.0, 1.2, and 1.4), resulting in nine formulations. Cement consumption was maintained constant at 195 kg/m3. The aggregates were characterized by particle size distribution and specific gravity analyses. Compressive strength and thermal conductivity were experimentally determined, and the results were statistically analyzed using analysis of variance (ANOVA). Both investigated factors significantly affected compressive strength, whereas thermal conductivity was predominantly influenced by mix proportion. The highest compressive strength values (>7 MPa) were obtained for the 1:1:5 formulation with w/c = 1.0. Thermal conductivity ranged from 1.23 to 1.74 W/m·K and was associated with variations in matrix densification and pore structure. The results indicate that the incorporation of ornamental stone fines is technically feasible and enables the adjustment of mechanical and thermal properties through mix-design control.