Concrete produced with recycled aggregate: a durability analysis for structural use

Lia Lorena Pimentel,Ana Elisabete Paganelli Guimarães De Avila Jacintho Jacintho,Giovanna Falzetta Rizzo,Patrícia Stella Pucharelli Fontanini

doi:10.1590/s1983-41952020000600013

Abstract

abstract: Construction and Demolition waste (CDW) is already used in many European countries as recycled aggregates to produce concrete for structural purposes. In Brazil, its use is still restricted to concretes with no structural function. The consumption of aggregates for the production of concrete is very large, and enabling the use of recycled aggregates in the production of concrete is essential to transform the civil construction industry into a more sustainable one. This work aimed to study the parameters that affect the durability of C30 grade concrete, produced with different types of recycled aggregate. We defined four types of coarse aggregates for carrying out this work: the natural (AN), the concrete (ARCO), the cementitious materials (ARCI) and the treated cementitious materials (ARCI Treated). We adopted 30% substitution content of natural aggregate for recycled aggregates. The treatment of the ARCI aggregate consisted of the application of water and cement solution, aiming to reduce its water absorption capacity. We determine the physical and mechanical characteristics of the concrete, in addition to carrying out indirect measurement tests of durability, by determining the permeability to air, penetration and migration of chloride ions, and determination of the carbonation depth. The results indicate that the concrete using the ARCO type aggregate, produced with 100% crushed concrete, presented characteristics like the reference concrete, indicating the possibility that it can be applied to reinforced concrete structures. As for the ARCI type aggregate, it presented inferior results when compared to the concrete reference for the tests of indirect measurement of durability, however, the concrete displayed good mechanical properties. The concrete produced with the treated ARCI did not perform better than the concrete with ARCI for most of the evaluated characteristics, indicating that the proposed treatment was not adequate.

Highlights

The construction industry is one of the human activities that most affects the environment [1]
It was observed that the reference concrete (T REF) presented a specific gravity that was greater than the other concretes, which can be explained by the specific mass of the natural coarse aggregate, shown in Table 1 to be greater than that of the recycled coarse aggregates
The use of coarse recycled concrete aggregate (ARCO) up to a content of 30% to replace natural aggregate does not change the resistance to axial compression

Summary

Introduction

The construction industry is one of the human activities that most affects the environment [1]. The recycling of construction and demolition waste for use as aggregates in the production of concrete would decrease the consumption of natural aggregates, and reduce energy consumption, transportation costs and, the emission of polluting gases [3], [4]. The authors estimated that 46% of the waste resulting from civil construction is recycled and reused, but they point out large variations between different countries [5]. Due to the high variability in the composition of civil construction waste, which generates different types of recycled aggregates, the use of these materials in the production of concrete for structural purposes is difficult, since the variability of recycled aggregates results in uncertainty about the characteristics of the concrete produced with this material

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Conclusion