EARLY-AGE EVOLUTION OF ELASTIC STIFFNESS AND COMPRESSIVE STRENGTH OF RECYCLED CONCRETE: INSIGHTS FROM MULTISCALE MICROMECHANICS MODELING

Author(s): Markus Königsberger (1), Stéphanie Staquet (1)
Paper category: Proceedings
Book title: SynerCrete’18 International Conference on Interdisciplinary Approaches for Cement-based Materials and Structural Concrete
Editor(s): Miguel Azenha, Dirk Schlicke, Farid Benboudjema, Agnieszka Jędrzejewska
ISBN: 978-2-35158-202-2
e-ISBN: 978-2-35158-203-9
Publisher: RILEM Publications SARL
Publication year: 2018
Pages: 677-682
Total Pages: 6
Language : English

Abstract: Recycled concrete, i.e. concrete which contains aggregates that are obtained from crushing waste concrete, typically exhibits a smaller elastic stiffness and a smaller compressive strength than conventional concretes. Based on a continuum micromechanics multiscale model, the mechanical origin and the extent of the reduction are studied herein. Therefore, recycled aggregates are considered as a mix of old cement paste and old aggregates, and they are considered to be embedded in a cement paste matrix at the scale of centimeters. Both, the old and the new cement paste are resolved at micrometer-sized observation scales. The multiscale representation allows for stiffness homogenization (micro-to-macro upscaling) as well as stress concentration (macro-to-micro downscaling), and the latter allows for strength predictions by considering that failure in most unfavorably loaded cement hydrates triggers macroscopic failure. The model suggests that the stiffness of recycled concrete significantly decreases with increasing replacement of natural by recycled aggregates. The strength reduction is less pronounced, in particular at early age, except if the old source concrete is significantly weaker than the targeted new concrete.

Online publication : 2018
Publication type : full_text
Public price (Euros) : 0.00