Synergic effect of waste brick powder, waste ceramic powder and marble powder on rheological behaviour, mechanical behaviour and carbon footprint of binary and ternary mortars

Abstract

Although waste brick powder (WBP), waste ceramic powder (WCP), and marble powder (MP) have been individually investigated as cement substitutes, their combined effects on rheological behaviour, mechanical performance, and strength-normalised environmental efficiency remain insufficiently understood. This study evaluates 37 mortar mixtures, including 12 ternary formulations with cement replacement levels ranging from 5% to 40%. Fresh-state properties were characterised through water demand, setting time, slump, yield stress, and plastic viscosity, whereas compressive strength was determined at 3, 7, 28, and 90 days. Strength-normalised embodied energy (EEI), embodied carbon (ECI), and material cost (MCI) were also assessed. WBP increased water demand and rheological resistance, whereas MP improved flowability through particle-packing and dilution effects. WCP exhibited intermediate rheological behaviour while maintaining satisfactory workability at moderate replacement levels. Binary mortars containing up to 25% WBP or WCP maintained compressive strength close to the control at 28 days. Among the ternary mixtures, 10% MP + 20% WBP achieved the highest 90-day compressive strength (≈65 MPa), whereas 10% MP + 10% WCP provided the best overall sustainability-performance balance, reducing EEI, ECI, and MCI by approximately 25% while maintaining satisfactory mechanical performance. These findings demonstrate the potential of optimised ternary recycled binders for producing lower-impact cement mortars.