MODELLING THE LONG-TERM BEHAVIOR OF RECYCLED AGGREGATES CONCRETE

Ghorbel E.; Wardeh G.; Peña Torres P. · fib Symposium (2022)

Resumen

The reuse of aggregates from deconstructed concrete is a necessity to preserve the environment, save exhaustible natural resources and meet recycling requirements. However, when natural aggregates are partially or completely replaced by recycled ones, certain properties are altered due to the presence of old cement paste contained in recycled aggregates. Therefore, creep is generally greater when recycled aggregates are incorporated into concrete. The objective of this work is to analyze the reliability of the predictive creep models proposed in the design standards and to make the necessary modifications to improve their performance. From the results available in the bibliographical references and based on several optimization approaches and statistical analysis of the results, new analytical expressions have been proposed for natural aggregates concrete. To consider the presence of recycled aggregates in concrete, the term (1+0.33m) was introduced in the modified expressions where m is the equivalent replacement ratio which represents the mass of recycled aggregates in the granular skeleton. A rheological model based on the Kevin-Voigt model was developed and was also extended to recycled aggregates concrete by introducing the corrective term (1+0.33m). A finite element viscoelastic modeling allowed the validation of this model for creep tests in compression and bending. The application of the viscoelastic approach for recycled aggregate concretes showed that the creep modeling requires the development of the Prony series with several terms. © Fédération Internationale du Béton – International Federation for Structural Concrete.