High-Performance Self-Compacting Concrete with Recycled Aggregates from the Precast Industry: Durability Assessment

Tiago Barroqueiro,Pedro R Da Silva,Jorge De Brito

doi:10.3390/buildings10060113

Tiago Barroqueiro, Pedro R Da Silva + Show 1 more

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https://doi.org/10.3390/buildings10060113

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Journal: Buildings	Publication Date: Jun 26, 2020
Citations: 22	License type: CC BY 4.0

Affiliation: Instituto Politécnico de Lisboa, University of Lisbon

Abstract

The main objective of this paper is to provide the industry with a simple and practical way of disposing and recovering recycled waste from precast reinforced concrete elements rejected during the quality control process, while minimizing the consumption of natural resources in the production of concrete and, consequently, significantly reducing the environmental impact of both (construction and demolition waste and extracting natural aggregates). In other words, with this work, the intention is to evaluate the feasibility of producing high-performance self-compacting concrete with a less environmental impact, by replacing natural aggregates (NA) with fine and coarse recycled aggregates resulting from the precast industry, which allows the future use of this type of aggregates in the industrial process without reservations concerning the expected durability performance. To achieve these objectives, six types of self-compacting concrete (SCC) were produced incorporating different amounts of recycled aggregates. Six replacement ratios for fine recycled aggregates (FRA) and coarse recycled aggregates (CRA) were considered: (FRA/CRA) 0/0; 25/25; 50/50; 100/100; 0/100 and 100/0%. Six different tests were carried out to characterize both the main concrete transport mechanisms and the main concrete degradation mechanisms, namely: the immersion water absorption test, capillary water absorption test, oxygen permeability test, chloride migration test, electrical resistivity test and carbonation test. The obtained results clearly demonstrate that, despite the negative influence of the inclusion of recycled aggregates, it is still possible to produce high-performance self-compacting concrete with perfectly acceptable durability properties.

Highlights

Since the beginning of the industrial revolution, the concentration of CO2 in the atmosphere has increased from 280 to 400 ppm in 2014 [1]
In order to facilitate the analysis of the results presented in Section 3, Table 3 presents, in addition to the mix proportions as well as the main mix parameters, some of the basic properties of the self-compacting concrete (SCC) produced
The durability tests of concrete allow evaluating its behavior towards external agents

Summary

Introduction

Since the beginning of the industrial revolution, the concentration of CO2 in the atmosphere has increased from 280 to 400 ppm in 2014 [1]. The annual production of concrete is approximately 1 × 1010 tonnes. This results in large amounts of CO2 emissions due, essentially, to the natural aggregates (NA) extraction and to the production of Portland cement. It is estimated that 1.7–2.1 tonnes of natural resources are used as raw material per m3 of concrete produced [3]. Given this current state, there is an urgent need to change the methods and principles of concrete manufacturing processes and to evaluate in detail the use of various residues in the concrete production. The use of some recycled materials, such as recycled aggregates (RA), can prevent the Buildings 2020, 10, 113; doi:10.3390/buildings10060113 www.mdpi.com/journal/buildings

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Conclusion