Resumen
Concrete mixing can lead to mechanical degradation of aggregates, particularly when
dealing with recycled concrete aggregates. In this work, the attrition of such materials during mixing
is studied by means of experiments and simulations. The effect of the presence of fines, water
addition, flow configuration of the mixer (co- or counter-current) and impeller frequency is discussed.
Experiments were performed in a laboratory Eirich mixer. Discrete element numerical simulations
(DEM) were performed on the same geometry by mimicking the behaviour of the material and,
in particular, the cohesion induced by water and the cement paste using either Hertz–Mindlin or
Hertz–Mindlin with Johnson–Kendall–Roberts (JKR) contact laws. The combination of the collision
energy spectra extracted from the DEM simulations and an attrition model allowed the prediction
of the mass loss due to attrition in 1-min experiments. Semi-quantitative agreement was observed
between experiments and simulations, with a mean relative error of 26.4%. These showed that higher
mass losses resulted from operation at the highest impeller speeds, co-current operation, and also
with the wet aggregate. Mixing of the agglomerate in the concrete mix resulted in a significant
reduction in attrition when compared to mixing aggregates alone. With further validation, the
proposed simulation approach can become a valuable tool in the optimization of mixing by allowing
the effects of material, machine and process variables to be studied on the mass loss due to attrition
Idioma original | Inglés |
---|---|
Número de artículo | 3007 |
Páginas (desde-hasta) | 3007 |
Número de páginas | 1 |
Publicación | Materials |
Volumen | 14 |
N.º | 11 |
DOI | |
Estado | Publicada - 1 jun 2021 |
Palabras clave
- Attrition
- Concrete mixing
- Discrete element method
- Recycled concrete aggregates
Project and Funding Information
- Funding Info
- This research was partially funded by the Brazilian Research Agency CNPq (grant number 310293/2017-0).