{"title":"Reactivity of aqueous carbonated cement pastes: Effect of chemical composition and carbonation conditions","authors":"Fábio Maia Neto , Ruben Snellings , Jørgen Skibsted","doi":"10.1016/j.jcou.2024.102970","DOIUrl":null,"url":null,"abstract":"<div><div>Aqueous carbonation of end-of-life concrete fines is a promising method to alleviate greenhouse gas emissions by CO<sub>2</sub> sequestration from point-source emitters. This produces a valuable material that can be utilized in new cement formulations. This study investigates effects of the composition of cement pastes and of the carbonation conditions on the reactivity and phase assemblage for aqueous carbonated Portland cement pastes incorporating silica fume, fly ash, and blast furnace slag. Results from <sup>27</sup>Al and <sup>29</sup>Si NMR show that hydration of the carbonated pastes under reactivity test conditions lead to phase assemblages dominated by a C-(A)-S-H phase, with reduced Al/Si ratio, as well as by ettringite and hemi/monocarbonate AFm phases. The results from the reactivity tests demonstrate that the carbonated blended cement pastes exhibit superior reactivity compared to carbonated neat Portland cement paste because of their increased fraction of reactive alumina and silica species. The variations in carbonation conditions (<em>i.e</em>., temperature, CO<sub>2</sub> gas concentration, and solution composition) do not alter significantly the reactivity of the carbonated pastes. These findings demonstrate the robustness of aqueous carbonation of concrete fines and support its wider application as a mean to reduce CO<sub>2</sub> emissions and enhance circularity of cement-based materials.</div></div>","PeriodicalId":350,"journal":{"name":"Journal of CO2 Utilization","volume":"89 ","pages":"Article 102970"},"PeriodicalIF":7.2000,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of CO2 Utilization","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2212982024003056","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Aqueous carbonation of end-of-life concrete fines is a promising method to alleviate greenhouse gas emissions by CO2 sequestration from point-source emitters. This produces a valuable material that can be utilized in new cement formulations. This study investigates effects of the composition of cement pastes and of the carbonation conditions on the reactivity and phase assemblage for aqueous carbonated Portland cement pastes incorporating silica fume, fly ash, and blast furnace slag. Results from 27Al and 29Si NMR show that hydration of the carbonated pastes under reactivity test conditions lead to phase assemblages dominated by a C-(A)-S-H phase, with reduced Al/Si ratio, as well as by ettringite and hemi/monocarbonate AFm phases. The results from the reactivity tests demonstrate that the carbonated blended cement pastes exhibit superior reactivity compared to carbonated neat Portland cement paste because of their increased fraction of reactive alumina and silica species. The variations in carbonation conditions (i.e., temperature, CO2 gas concentration, and solution composition) do not alter significantly the reactivity of the carbonated pastes. These findings demonstrate the robustness of aqueous carbonation of concrete fines and support its wider application as a mean to reduce CO2 emissions and enhance circularity of cement-based materials.
期刊介绍:
The Journal of CO2 Utilization offers a single, multi-disciplinary, scholarly platform for the exchange of novel research in the field of CO2 re-use for scientists and engineers in chemicals, fuels and materials.
The emphasis is on the dissemination of leading-edge research from basic science to the development of new processes, technologies and applications.
The Journal of CO2 Utilization publishes original peer-reviewed research papers, reviews, and short communications, including experimental and theoretical work, and analytical models and simulations.