RESEARCH ARTICLE


Influence of Heterogeneity, Typology, and Contaminants of Recycled Aggregates on the Properties of Concrete



Gilberto A. da Silva Neto1, João P. V. de Oliveira1, Pedro V. Salles2, Raphael T. de Vasconcelos Barros1, Maria T. Paulino1, White J. dos Santos1, *
1 Department of Materials Engineering and Construction, Federal University of Minas Gerais, Belo Horizonte, Brazil
2 Department of Civil Engineering, Federal Center for Technological Education of Minas Gerais, Belo Horizonte, Brazil.


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Creative Commons License
© 2020 da Silva Neto et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Materials Engineering and Construction, Federal University of Minas Gerais, Belo Horizonte, Brazil; E-mail: white.santos@demc.ufmg.br


Abstract

Background:

The depletion of raw material resources, the preservation of the environment, and the need to compensate economic imbalances drive research efforts regarding the application of Construction and Demolition Waste (CDW) in concretes.

Objective:

This paper aimed to assess the influence of the heterogeneity, typology, and presence of contaminants of CDW (collected in different seasons and locations) on the mechanical properties and durability of concretes.

Methods:

Characterization procedures were performed for the aggregates (visual quantification and physical properties of the constituents), and for the concretes (compressive strength, splitting tensile strength test, modulus of elasticity, water absorption, porosity, electrical resistivity, carbonation depth, and digital microscopy). The replacement rate of natural aggregate for CDWA was of 20% in three different particle sizes: sand, gravel 0, and gravel 1.

Results:

The characteristics of the samples of CDW were very variable, influenced by the season and location of collection. The presence of materials with elevated porosity (ceramics, mortars) was observed in some samples and required increases in mixing water volume to keep the concretes’ consistency. A wide variation in mechanical properties caused by the CDWA constituents was also observed. Regarding the durability of the concretes, it was proven the greatest sensibility of this property to contaminants, thus requiring the removal of deleterious materials to using CDWA in structural concretes in order to avoid the formation of vesicles and guaranteeing their life span.

Conclusion:

The heterogeneity, typology and contaminant content significantly influence the analyzed properties. Besides, the segregation of waste at source makes the use of CDWA feasible in concretes.

Keywords: Construction and demolition waste, Recycled aggregates, Structural concrete, Mechanical properties, Durability, Waste variability.