Accelerated Carbonation of Recycled Aggregates Using the Pressurized Supercritical Carbon Dioxide Sparging Process
| Autor: | Chul-Woo Chung, Jin Young Park, Minhee Lee, Sookyun Wang, Jinkyun Lee |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
carbonation
lcsh:QE351-399.2 Carbonation 0211 other engineering and technologies PH reduction 02 engineering and technology 010501 environmental sciences engineering.material 01 natural sciences Portlandite chemistry.chemical_compound supercritical carbon dioxide 021105 building & construction concrete waste Sparging 0105 earth and related environmental sciences Aggregate (composite) Supercritical carbon dioxide lcsh:Mineralogy Extraction (chemistry) Geology Geotechnical Engineering and Engineering Geology recycled aggregate chemistry Chemical engineering engineering Carbonate sparging |
| Zdroj: | Minerals, Vol 10, Iss 486, p 486 (2020) Minerals Volume 10 Issue 6 |
| Popis: | The carbonation of recycled aggregate was accelerated by sparging with supercritical carbon dioxide (scCO2) to reduce the amount of time needed for carbonation, which is necessary for the pH neutralization of recycled aggregate. To accelerate the carbonation process, pressurized scCO2 was sparged into two different types of recycled aggregates immersed in water for 1 h, followed by standstill for 2 h (in total, a 3 h treatment process). The reduction of the pH of the treated aggregates due to carbonation was investigated using batch extraction experiments. A continuous column extraction experiment for the scCO2-sparged recycled aggregate was also performed to identify the effect of pH reduction under the condition of non-equilibrium reaction. From XRD, SEM/EDS, and TG/DTA analyses, much of the portlandite in the recycled aggregates was consumed. In its place, calcite was created as a secondary mineral during only 3 h of treatment (1 h scCO2 sparging and 2 h stationing), indicating satisfactory carbonation of the aggregate. The results of the batch extraction experiments for both of the two recycled aggregate types also showed that the average pH of scCO2-sparged aggregate decreased from 12.0 to < 9.8 (the tolerance limit for recycling). The pH of the eluent from the column packed with the scCO2-sparged aggregate also remained as < 9.8, suggesting that a 1 h scCO2 sparging process is sufficient to carbonate waste concrete aggregate and to create an alternative construction material resource. |
| Databáze: | OpenAIRE |
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