Valorization of construction and demolition waste into totally recycled concrete with thermoactivated cement: environmental performance and durability

The valorization of construction and demolition waste (C&DW) into new building materials is essential for achieving the circular economy and low-carbon targets. This study introduces the concept of totally recycled concrete (TRC), produced entirely from thermoactivated recycled cement (RC) and recycled aggregates (RA). The mechanical, durability, and microstructural properties of TRC were evaluated, alongside a quantitative assessment of embodied carbon emissions. Results show that although TRC exhibits moderate strength reductions, its performance remains within acceptable engineering ranges. The transport properties are governed by RA, with a clear correlation identified between water absorption and gas permeability, providing indicators for service-life prediction. Most importantly, carbon footprint analysis revealed that TRC reduces embodied CO2 emissions to only 29.6% and 26.1% of conventional concrete, respectively, demonstrating substantial mitigation potential. These findings highlight that integrating 100% recycled binders and aggregates enables complete C&DW recycling and offers a scalable route for carbon reduction in the construction.