Technical and environmental assessment of CO2-cured alkali-activated pervious paving blocks incorporating recycled aggregates

The study explores the development of 200 × 100 × 60 mm alkali-activated vibro-compacted pervious paving blocks incorporating waste precast concrete as aggregates, along with fly ash and mine tailings as binders. This approach embodies the principles of circular economy and contributes to the decarbonisation of construction materials. The mechanical performance, permeability, and environmental impact were evaluated, emphasising sustainability without compromising functionality. These properties were assessed according to the European standard EN 1338 to determine their technical feasibility as well as certification and marketability. The results showed that the integration of accelerated carbonation further enhanced mechanical properties and durability as alkali-activated permeable pavers with 100 % recycled aggregate incorporation led to a 34 % increase in compressive strength and a 50 % reduction in abrasion wear. Permeability performance was also analysed and revealed suitable infiltration rates for stormwater management in urban pavements. The life cycle assessment, based on a gate-to-gate approach, revealed that employing industrial by-products and recycled materials significantly decreases greenhouse gas emissions, demonstrating the eco-efficiency of the proposed solution, with a carbon footprint of 129.2 kg CO 2eq , corresponding to a 49 % reduction compared to Portland cement block counterparts, which registered 253.7 kg CO 2eq . These findings position the developed materials as a technically and environmentally viable alternative for pervious paving applications, promoting resource conservation and environmental stewardship in the construction industry. • Alkali-activated blocks with reduced CO 2 emissions by 49 % vs. Portland cement blocks. • Recycled aggregate blocks with compressive strength up to 14.5 MPa post-carbonation. • Recycled aggregate presence enhanced paving blocks’ skid resistance by over 10 %. • Carbonation-enhanced durability resulting in reduced abrasion mass loss of 51.3 %. • Recycled aggregates enhanced infiltration, balancing porosity and strength.