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PRINCIPAL PUBLICATION AND AUTHORS

Crystallisation and phase transformation processes during clinkering in portland cement (pc) by means of in situ and ex situ analyses, M. Cantaluppi (a), V. Diella (b), A. Pavese (c), M. Marchi (d), N. Marinoni (a), Constr. Build. Mater. 394, 132261 (2023); https:/doi.org/10.1016/j.conbuildmat.2023.132261 (a) Earth Sciences Ardito Desio Department, Università degli Studi di Milano, Milano (Italy) (b) Consiglio Nazionale delle Ricerche, IGAG, Sezione di Milano, Milano (Italy) (c) Earth Sciences Department, Università degli Studi di Torino, Torino (Italy) (d) Global Product Innovation (GPI) Department, Italcementi S.p.A., Heidelbergcement Group, Bergamo (Italy)

Crystallisation and phase transformation processes during clinkering in Portland cement

Reducing the environmental impact of concrete production by using recycled materials is a crucial target for sustainability in the building industry. In-situ and ex-situ X-ray powder diffraction was used to study the effects of incorporating industrial waste materials in the manufacture of Portland cement a process called clinkering on the cement s performance.

Portland cement (PC) is one of the most widely used construction materials. Its production is totally dependent on primary raw materials such as limestone and clay minerals. An important challenge for the cement industry is reusing industrial waste (i.e. impure material) as a feasible substitute for natural raw materials, but variability in terms of mineralogical and chemical composition can have significant effects both positive and negative on the technical performance of the final cement.

This study investigated the effects of MgO, SO3, Na2O and Cl some of the most frequently occurring minor components in industrial

clinkers on PC raw mixtures by means of in-situ and ex-situ X-ray powder diffraction (XRPD) at beamline ID22 (Figure 129), scanning electron microscopy and X-ray fluorescence experiments.

The results showed some positive effects of Cl-doping: (i) inhibiting Ca3Al2O6 formation; (ii) promoting M1-Ca3SiO5 (hatrurite) and Ca12Al14O33 (mayenite) crystallisation, and (iii) lowering its melting point and viscosity. This knowledge could contribute to the development of a circular economy in cement manufacturing.

Fig. 129: In-situ XRPD patterns collected at ID22 from 1062-1423°C

for PC doped with 2, 1 and 0.5wt.% of MgO, SO3 and Cl, respectively.

Bragg peaks are highlighted with the cement notation.