Effects of TiO2 waste on the formation of clinker phases and mechanical performance and hydration of Portand cement

• Published in: Cement (Amsterdam, Netherlands) Netherlands), 2022-09, Vol.9, p.100036, Article 100036
• Main Authors: Andrade Neto, José S., Mariani, Bruna B., Amorim Júnior, Nilson S., Ribeiro, Daniel V.
• Format: Article
• Language: English
• Subjects: Hydration; Mineralizer; Portland clinker; Unreacted ore waste (UOW)
• ISSN: 2666-5492; 2666-5492
• DOI: 10.1016/j.cement.2022.100036

•The effects of incorporating UOW into Portland clinker raw meal on the formation of phases and mechanical performance and hydration of cements were evaluated.•Clinkers containing 1.29%, 2.58%, and 5.16% of UOW, which correspond to contents of 0.5%, 1.0%, and 2.0% of TiO2, were produced at 1340 ˚C.•UOW acted as a mineralizer during clinker production, reducing the required temperature, increasing the alite content, and the size of the crystals formed.•The incorporation of UOW into the clinker raw meal resulted in an initial delay in the hydration process, in addition to delaying the depletion of sulfates.•Owing to the increase in the alite content, the incorporation of 1.29% of UOW into the clinker raw meal resulted in an increase in the mechanical strength in the first days. The incorporation of different levels of UOW into Portland clinker raw meals and its effects on the clinker and cement properties were evaluated. Clinkers were produced and characterized by X-ray diffractometry (XRD) and optical microscopy; the cements were produced and physically characterized. Finally, pastes were produced and analyzed using isothermal calorimetry, thermogravimetry, XRD, and compressive strength tests. UOW, when added up to 1.29% in Portland clinker raw meal, acts as a mineralizer, increasing the content of alite by 6.44%. The incorporation of UOW reduces the hydration rate in the first days owing to the increase in the size of the alite crystals and delays the point of sulfate depletion due to the increase in the SO3 content of the clinkers. Owing to the higher content of alite formed, the cement produced from the raw meal with 1.29% of UOW presents the highest early mechanical strength (up to 7 days).