Page 35 - New Trends in Green Construction

ESTIMATION OF THE PHYSICAL-MECHANICAL PROPERTIES OF RECYCLED AGGREGATES FROM THEIR COMPONENTS
Pilar Muñoz-Moreno, Antonio López-Uceda, Enrique Fernández-Ledesma, Lorenzo Salas-Morera, José Ramón Jiménez.
Keywords: Statistical analysis, circular economy, recycled aggregate, physical-mechanical properties. 1. Introduction
Every day, huge amounts of construction and demolition waste (CDW) are produced worldwide as a result of the upgrade in the construction sector. This results in environmental problems directly related, like the constant consumption of non-renewable raw materials and the problems derived from their storage in landfills. An alternative to solve these problems is to recover these waste materials. Since the 80’s of the previous century, there has been considerable progress in CDW recycle systems (Tam et al., 2018), not only in the methods of recovery from CDW into recycled aggregate (RA) but also on the ways and techniques of its utilisation in construction industry.
Until a few years ago, most of the studies focused on recycled concrete aggregates (RCA), which provide better structural characteristics in the produced concrete. However, mixed recycled aggregates (MRA) are the majority RA; the main components of these aggregates are concrete, mortar, unbound natural aggregates and ceramic particles, although small percentages of gypsum, asphalt and wood could be present. The study of the composition of RA and their main properties have been widely studied in the literature. Silva et al. (2014) performs a statistical analysis of the main properties of recycled aggregates for use in concrete. However, a few authors like Barbudo et al. (2012) studied from a statistical point of view the relationship between the composition of RA and their physical-mechanical properties.
The aim of this study is to analyse the influence of components on the RA physical-mechanical properties.
2. Materials and methods
Thirty-five RA were studied, nineteen were RCA and sixteen MRA. The samples were collected from different recycling plants. A composition test was performed to each aggregate, separating the main components of RA: concrete (Rc1), mortar (Rc2), unbound natural aggregates (Ru) and ceramic particles (Rb) as independent variables. Six physical-mechanical properties of RA were selected as dependent variables: oven-dried particle density (rd), apparent particle density (a), saturated and surface dried particle density (SSD), water absorption after 24 hours (WA) (UNE- EN 1097-6: 2014), resistance to fragmentation by Los Angeles test (LA) (UNE-EN 1097-2: 2010) and aggregate crushing value (ACV) (BS 812-110:1990).
An analysis of variance was carried out to determine the relationships between the independent variables and the six dependent variables. In the cases where a dependency relationship was found, a regression analysis was conducted (multiple linear correlation, polynomial or exponential function).
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New Trends in Green Construction