Assessment of the potential use of construction and demolition waste (CDW) fines as eco-pozzolan in binary and ternary cements

Construction and demolition waste (CDW) represents a significant portion of the total volume of solid waste generated worldwide, an alternative is to use the fine fraction as eco-pozzolan. The study aims to evaluate the use CDW fines (< 63 µm) as supplementary cementitious material (SCM) in binary (cement and CDW) and ternary (cement, CDW and metakaolin) matrices. Binary mixtures were prepared with 5–20% CDW and ternary mixtures with up to 50% substitution (5–40%CDW, 45–10%MK). Experimental techniques of X-ray fluorescence (XRF), particle size distribution, X-ray diffraction (XRD), SEM-EDS microscopy, thermogravimetry (TG) and mercury intrusion porosimetry (MIP) were used. The physical, mechanical and microstructural properties of the pastes were evaluated. The results show that CDW fines can be used in large quantities in ternary blends to refine the pore structure, reduce water absorption and maintain mechanical strength in the 40 MPa class. •Cementitious pastes containing high levels of CDW fines were investigated.•CDW has a typical composition of cementitious materials and low pozzolanic reactivity.•Blending CDW and MK results in a more densified matrix with lower water absorption and void content.•The combination of CDW and MK in ternary matrices allows for the refinement and reduction of the pore diameter.