Page 31 - New Trends in Green Construction

BIKE LANE MADE WITH SCREENING WASTES AND MIXED RECYCLED AGGREGATES FROM CDW
Javier Tavira, José Ramón Jiménez, Jesús Ayuso, Antonio Jesús González-Barrios, Enrique Fernández-Ledesma, Antonio López-Uceda,
Keywords: recycled mixed aggregates, screening wastes, construction and demolition waste, backcalculation, Falling Weight Deflectometer.
1. Introduction
Construction Demolition Wastes (CDW) are still mainly used as a fill material or dumped in land areas, these practices harms the environment and makes it impossible to reach the 70% limit of CDW recovered by 2020 by the Waste Framework Directive, it is a must for every agent involved in the management of these wastes to find new ways to reuse CDW. No other study was found regarding the usage of screening wastes (SW) in unbound pavement layers. As a result of its high fine fraction and impurities, SW are not used as granular bases and subbases of roads and placed in landfills deteriorating our environment. The main objective of this study was to perform a long time study of its use in the granular layers of a bike lane. This experimental bike lane validates the use of these recycled materials as granular base-subbase layers, these recycled materials do not satisfy the chemical and physical specifications to be used in roads (PG-3, 2015). Elastic moduli of pavement layers are basic parameters used to estimate durability, in this research was determined along the two years period of the study through backcalculation. These moduli can be used to compare bearing capacities of pavement sections built with recycled materials or natural aggregates. Ecological footprints caused by road infrastructures can be reduced by the use of recycled materials instead of natural materials (Vieira and Pereira, 2015). To the best of our knowledge, there were no previous studies regarding the use of SW obtained from CDW as unbound layers materials in the construction of roads or bike lanes.
2. Material and methods
The experimental bike lane (EBL) was built using two recycled materials from CDW: a recycled mixed aggregate (RMA-1) and a recycled mixed material from screening waste (RMSW-1). The first step after arrival of CDW was to reduce bigger fragments that could not be crushed, then primary screening (0/20 mm) removed the finest particles with more impurities and improved the quality of the recycled aggregates subsequently obtained. Then, RMSW-1 was collected. An impact crusher ground particle greater than 20 mm. The ground materials were screened by a 40- mm sieve. At this point, materials larger than 40 mm were returned to the impact crusher to reduce their size. After passing through the sieve, a magnetic belt conveyor was used to remove metallic elements. Finally, a blower removed light particles (Fig. 1). Deflections were measured with an FWD to evaluate the mechanical behaviour of the structural layers and to determine the Young's modulus of the natural and recycled materials (Fig. 2).
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New Trends in Green Construction