Physical and Mechanical Properties and Partial Cradle-to-Gate Global Warming Potential of Mortars Incorporating Ecuadorian Waste Marble Powder as a Partial Cement Replacement

The physical and mechanical performance of mortars incorporating waste marble powder (WMP) depends on powder characteristics and mixture design, whereas conditioning energy influences environmental impact. This study examined 0, 5, 10, and 15% cement replacement with Ecuadorian WMP at a water-to-binder ratio of 0.50 and a binder-to-fine-aggregate ratio of 1:2.1. WMP was characterized by scanning electron microscopy, image analysis, X-ray fluorescence, and X-ray diffraction. Mortar properties were evaluated at 28 days alongside a partial cradle-to-gate assessment. Number-based D50 and D90 were 3.145 and 8.097 µm. In the tested batches, 15% WMP reduced mean water absorption by immersion and open porosity by 33.6% and 30.1%, respectively. Mean compressive strength ranged from 3.66 to 6.38 MPa, but high within-batch variability at 5% and 10% replacement and one batch per formulation prevented establishment of a reproducible strength effect. Laboratory-scale conditioning increased global warming potential by 4.08–12.25% relative to the control. The 15% formulation warrants further investigation for non-structural rendering and plastering, subject to independent batches and additional performance and durability testing.