Characterization, mechanical strength, rheological properties and life cycle assessment of fully recycled concrete through geopolymer technology

This study presents a sustainable method for recycling Ordinary Portland cement concrete (OPCC) using geopolymer technology, reducing the need for new cement and aggregates. By including geopolymerization, the process offers significant ecological and economic advantages over conventional methods. Crushed and pulverized waste concrete was used as recycled granulate (RA) and binder, using recycled clay brick powder (RBP) as an additive. Based on the results, the incorporation of RA into recycled geopolymer concrete (GRC) improved the compressive strength by 11.7%, with a maximum compressive strength of 44.3 MPa and a tensile strength of 4.77 MPa. Replacing recycled concrete powder (RCP) with 5% wt% resulted in a 21% reduction in compressive strength (35 MPa) and a 25.3% reduction in tensile strength (3.56 MPa). A further increase in the RBP content to 15 wt% reduced the compressive strength to 27.65 MPa (37.5% reduction). The RBP content directly effects on the flowability and improves the appearance of the GRC and reduces cracks. When comparing total eco-cost, GRC (128.9 €/m³) proved to be more environmentally friendly than OPCC (140.4 €/m³). The developed GRC meets construction standards and offers a promising alternative to conventional recycling and exceeds OPCC in terms of eco-cost and sustainability.