Chemical and Mechanical Characterization of a Novel CSA Blended Cement Based on CDW Inorganic Fractions

Cement is a construction material widely used to improve the socio-economic development of a society. However, for its production path, it needs significant amounts of raw materials (limestone, clay, bauxite, etc.), which is currently outside the Environmental Policies. For this reason, any alternative to manufacture sustainable eco-cement based on the circularity of industrial waste is a priority line for the cement sector. This work presents the characterisation results of a calcium sulfoaluminate cement clinkerized (CSA-L), in a laboratory muffle at 1250ºC for 60 min, by partial replacement of raw materials by different construction and demolitions wastes (CDW) from the fine fraction of concrete (<5 mm), deconstruction building laminated glass and recycled gypsum. Subsequently, its physical-mechanical behaviour (water demand, setting times, soundness, mechanical properties and microporosity) was analysed in an eco-blended cement made by combining 90% OPC and 10% CSA (commercial and clinkerized ones), as preliminary studies for the manufacture of eco-cement materials for 3D printing. The results obtained demonstrate the feasibility of using CDW as secondary raw materials for the formation of a CSA eco-cement, with a mineralogical composition consisting of 24% Ye’elimite (C4A3$), 6% Larnite (α-C2S) and 31% Brediggite (Ca7Mg(SiO4)4. This eco-CSA-L cement shows an enriched nature in Brediggite with respect to commercial CSA-C cement. The binary mixture of cements (OPC + 10% CSA-L) shows a rheological and mechanical behaviour close to the reference OPC.