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ALTERNATIVES FOR THE PRODUCTION OF STRUCTURAL CONCRETE WITH FULL RECYCLED AGGREGATES



Author(s): Taimí Castaño Cardoza, Sandra Lichtblau, Stefan Linsel, José Fernando Martirena Hernández
Book Title: III Progress of Recycling in the Built Environment
Editor: I. Martins, C. Ulsen and S. C. Angulo
e-ISBN: 978-2-35158-158-2
Publisher: RILEM Publications SARL
Publication year: 2015
Pages: 175-183
Total Pages: 8
Language: English


Abstract: Aggregates from recycled materials are softer and more porous than natural aggregates, and thus an increase in water demand is induced. This paper presents the production of a structural concrete made entirely with mixed recycled aggregates. The influence of material under 63 μm in mortar is discussed. The use of 6% of this material in mortars increases the water demand and brings about a reduction of strength, but it decreases the effective porosity of the matrix, increases the density of the ITZ and contributes to increase impermeability of the matrix, as proven on alkalis expansion tests carried out in mortars. The high porosity of the coarse fraction of recycled aggregate is reduced by coating of the 4-8 mm fraction with a 0.16-0.23 mm cement film, which compensates the high water demand of recycled aggregate, as demonstrated in the porosity- and the frost-thaw-tests. For the same water to cement ratio, the amount of superplasticizer, used in concrete made with encapsulated aggregate, was reduced to a half in comparison with to the non-coated reference. Furthermore the concrete reaches a compressive strength about more than 30 MPa. The encapsulation leads to a significant improvement of the impermeability in the concrete structure, which is probably caused by the densification of the pore structure.


Online publication: 2015
Publication Type: full_text
Public price (Euros): 0.00


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