Valorization of Fine Recycled Aggregates Contaminated with Gypsum Residues: Characterization and Evaluation of the Risk for Secondary Ettringite Formation

Fine recycled aggregates (FRA) (0/4 mm) are up to now not valorized on a high enough level because of characteristics like an elevated water absorption, higher fines content, and the presence of contaminations. Leftover gypsum residues from the construction site can cause internal sulfate attack whe...

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Bibliographic Details
Published in:Materials 2020-11, Vol.13 (21), p.4866
Main Authors: Colman, Charlotte, Bulteel, David, Rémond, Sébastien, Zhao, Zengfeng, Courard, Luc
Format: Article
Language:English
Subjects:
Aggregates
Cement
Civil engineering
construction and demolition waste
Construction sites
Contamination
Curing
Demolition
Engineering Sciences
Engineering, computing & technology
Ettringite
fine recycled aggregates
Gypsum
Ingénierie civile
Ingénierie, informatique & technologie
Mortars (material)
Recycling
Recycling centers
Residues
secondary ettringite formation
sulfate attack
Swelling
Water absorption
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Summary:Fine recycled aggregates (FRA) (0/4 mm) are up to now not valorized on a high enough level because of characteristics like an elevated water absorption, higher fines content, and the presence of contaminations. Leftover gypsum residues from the construction site can cause internal sulfate attack when FRA are incorporated into new structures. Concern about this deteriorating reaction plays an important role in the rejection of FRA. In this study, samples of FRA from different recycling centers were characterized and incorporated into mortars. They were then subjected to swelling tests in order to evaluate the development of sulfate attack. Reference materials with different amounts of sulfates were used as a comparison. Results showed a variable sulfate content in industrial FRA, depending heavily on the source of the materials. In all but one case, the total amounts surpassed the acceptable sulfate contents specified in the European standard EN 206, meaning the FRA would be rejected for reuse in concrete. Nevertheless, swelling tests demonstrated that these contamination levels did not pose a risk for sulfate attack. These results indicated that the incorporation of FRA leads to acceptable mechanical performances and that the sulfate limit could be reviewed to be less strict.
ISSN:1996-1944
1996-1944
DOI:10.3390/ma13214866