Novel process for valorising excavated clay to produce light weight aggregates by addition of carbonaceous residue, cement and CO2 curing

precipitation by 70% with respect to the carbonated aggregates not containing the carbonaceous residue. This calcite precipitation and densification resulted in a point load compressive strength (1.3 MPa) of medium-sized (≥15 mm) SCCAs, equivalent to those of commercially used expanded glass foam aggregates. A proof-of-concept investigation of the cast concrete blocks in which SCCAs replaced 20 vol% of the natural aggregate showed a 7-day compressive strength exceeding 22 MPa, indicating their potential for use in masonry construction in accordance with Eurocode 6. Carbon footprint analysis highlighted that even considering the additional emissions related to the manufacturing steps, concrete manufactured using the aggregate formulation proposed in this study would present a 15% lower footprint, due to the carbon sequestered in the carbonaceous residue. The results of the study hence show the potential application of SCCAs as backfill materials or even for the manufacturing of medium-strength concrete products.