Strength-porosity correlation and environmental analysis of recycled Portland cement.
In: Resources, Conservation & Recycling, Jg. 190 (2023-03-01), S. N.PAG
academicJournal
Zugriff:
• The total porosity of recycled Portland cement pastes (R-OPC/P) was estimated through Powers' model. • Porosity-strength relationship has a single trend for (re)hydrated Portland cement pastes. • Binder efficiency and environmental impact were analyzed by combined water fraction (cwf) and carbon dioxide intensity index (CO 2 index). • The dispersant use in R-OPC/P reduced the porosity reduced by 15%. The compressive strength increased by 2.5 times. Recycled cement is obtained by heat treating hydrated cementitious materials. At 550 °C, decarbonation does not occur owing to the low CO 2 emissions during production. A partial regain of the binder ability is observed during rehydration. However, recycled cement has limited strength owing to its physicochemical characteristics, which require elevated water demand. Herein, the porosity and compressive strength of rehydrated cement paste were optimized through water/binder ratio reduction and dispersant use. The cement pastes were fully dispersed based on rotational rheometer analysis. The experimental data were complemented by a literature overview. Consequently, a single strength-porosity relationship was found for (re)hydrated pastes. Decreasing the water demand is key to reducing porosity and improving strength. The recycled cement paste produced in this study achieved the best binder efficiency index (cwf of 0.27 g/g) compared with those in the literature, 48% total porosity and 15 MPa at 28 days. Cement recycled at 550 °C indicated a 78% reduction compared to OPC emissions. Despite the low environmental impact of recycled cement, its low strength when used alone makes its environmental efficiency similar to that of Portland cement. [Display omitted] [ABSTRACT FROM AUTHOR]
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Strength-porosity correlation and environmental analysis of recycled Portland cement.
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Autor/in / Beteiligte Person: | Zanovello, Mateus ; Baldusco, Raphael ; John, Vanderley M. ; Angulo, Sérgio C. |
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Zeitschrift: | Resources, Conservation & Recycling, Jg. 190 (2023-03-01), S. N.PAG |
Veröffentlichung: | 2023 |
Medientyp: | academicJournal |
ISSN: | 0921-3449 (print) |
DOI: | 10.1016/j.resconrec.2022.106763 |
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