Project
Calcium Aluminate Blended Cements Incorporating Engineered Residues
The pressure to decarbonize the cement industry in light of sustainability goals has been motivating the search for new types of supplementary cementitious materials (SCM) in the recent decades. Industrial residues, which otherwise end up in landfills or find low added-value applications, are of particular interest in near-zero-waste process schemes. This thesis explored the valorization of pre-treated residues as SCM in calcium aluminate (CAC) blended cements. These residues included non-ferrous metallurgy (NFM) slags, municipal solid waste incinerator bottom ashes, jarosite and paper-fabrication residues. The evolution of the mechanical strength of mortars containing highly-amorphous Fe-rich NFM slags demonstrated their positive contribution to the blend. For this reason, the main focus of this study was dedicated to binary CAC-calcium sulfate and ternary CAC –calcium sulfate-Portland cement (PC) blends incorporating Fe-rich slags. The mechanical strengths and dimensional stability were followed over a curing period of 1 year. The degree of slag hydration was quantified using several methodologies based on microscopy, tomography and Mössbauer spectroscopy. The phase assemblage evolution was thermodynamically-modeled and experimentally followed using various characterization techniques. The fate of Fe during hydration was given a special attention in the analyses. In the end, the overall properties of the blends supported their valorization potential in this application.