On the Development of a Technical Specification for the Use of Fine Recycled Aggregates from Construction and Demolition Waste in Concrete Production.

Diogo Pedro,Miguel Bravo,António P. C. Duarte,Luis Evangelista,Jorge de Brito

doi:10.3390/ma13194228

Abstract

The possibility of using recycled aggregates from construction and demolition waste (CDW) in concrete is rather widely agreed upon when it comes to the use of coarse recycled aggregates. However, this is not the case when fine recycled aggregates (FRA) are considered, as it is deemed that these seriously impair the behaviour of concrete. Hence, this work presents a technical specification proposal for the use of FRA from CDW in concrete, to attempt to fill this gap in legislation. The specification is based on a wide collection of experimental results, from which it is shown that for low incorporation ratios (up to 25%), the properties of concrete with FRA from CDW are comparable to those of a reference concrete. The intended international scope of the specification is ensured by the fact that FRA from CDW are typified by composition (percentage of concrete, masonry, glass, etc.) rather than by geographical origin or construction type. It is shown that, after typifying the FRA and assuming, as per design, the acceptable percentage losses (relative to a reference concrete) of mechanical, durability-related and long-term physical properties, if the maximum incorporation ratios proposed of each type of FRA are used, the variation of properties remains within the limits established.

Highlights

The construction sector is amongst the most environmental impacting in Europe, consuming high amounts of raw materials and energy. This contributes to a high generation of construction and demolition waste (CDW), which is the largest fraction of waste produced in the European Union: about 900 million tonnes of the total 3000 million tonnes of waste generated yearly [1]
The specification proposal was inspired on the philosophy of the existing one on the use of coarse recycled aggregates, CRA, in Portugal-LNEC E
Existing literature shows that the use of fine recycled aggregates (FRA) from CDW in concrete is feasible but legislation on their use is still nearly absent

Summary

Introduction

The construction sector is amongst the most environmental impacting in Europe, consuming high amounts of raw materials and energy. The main novelty of this work, aiming at advancing the in-depth understanding between the properties of RA from CDW and the resulting concrete produced, is two-fold: (i) presentation of a specification for the use of fine RA from CDW in concrete (still absent) and (ii) the development of rules accounting for RA composition (rather than origin) and based on an assumed decrease in properties (rather than on the imposition of minimum concrete strength classes). To this end, the main objectives of the work, which coincide with the following sections, are:. A detailed presentation of the technical specification; Validation of the specification considering the FRA used in the experimental campaign

Summary of Experimental Campaign

Mechanical

Proposal of a Specification

Framework

Aggregates Classification

Implementing Rules

Quality Control

Validation of the Proposed Specification

Findings

Conclusions