3251
Experimental reinforced soil walls built with recycled construction and demolition
waste (RCDW).
Murs expérimentaux de sol renforcé construits avec résidus de construction et démolition recyclés
Santos E.C.G.
Polytechnic School of the University of Pernambuco
Palmeira E.M.
University of Brasília
ABSTRACT: In spite of its well known evolution, the Civil Engineering is yet pointed out as remarkable raw material consumer and
one of the leading waste generators in modern society. Nowadays, construction and demolition waste became a complex problem to
government authorities due to its economical and environmental impacts. Bearing in mind these aspects, the use of recycled
construction and demolition waste (RCDW) in reinforced soil structures appears to be an interesting proposition. In order to
investigate this proposal, two instrumented full-scale wrapped face geosynthetic reinforced walls were constructed using recycled
construction and demolition waste as backfill material. The instrumentation plan consisted of more than 400 instruments and required
the adoption of a careful installation process due to the presence of coarse particles of RCDW. The results have shown that RCDW
has excellent mechanical properties - with low variation – which allow its use not just in the suggested proposal but in other
geotechnical works. Additionally, based on lessons learned during the construction process, some recommendations are presented
with the intention of promoting a better performance of reinforced walls built with this “novel construction material”.
RÉSUMÉ : Malgré sa nette évolution, le génie civil est toujours indiqué comme un grand consommateur de matière première et un
des leaders de la génération de résidus dans la société moderne. Actuellement, le résidu de construction et démolition est devenu un
problème complexe pour les autorités municipales en raison des impacts économiques et environnementaux. Compte tenu de ces
aspects, l'utilisation des résidus de construction et démolition recyclés (RCD-R) dans les structures de sol renforcé, émerge comme
une proposition intéressante. Pour investiguer cette proposition, deux murs renforcés avec géosynthétiques de face enveloppé ont été
construits avec RCD-R comme matériaux de remplissage. Les murs ont été construits à l'échèle réel et instrumentés. L'instrumentation
consistait a plus de 400 instruments et elle a demandé l'adoption d'un procès minutieux d'installation en raison de la présence des
cailloux du RCD-R. Les résultats ont montré que le RCD-R possède d'excellentes propriétés mécaniques – avec faibles coefficients de
variation – qui permettent leur utilisation non seulement dans la proposition suggérée, mais aussi sur d'autres ouvrages géotechniques.
De plus, basée sur les leçons apprises au cours du processus de construction, certaines recommandations ont été déposées dans le but
de promouvoir une meilleure performance des murs renforcés construits avec ce "nouveau matériaux".
KEYWORDS: reinforced soil wall, geosynthetics, recycled construction and demolition waste, instrumentation.
1 INTRODUCTION.
The Geotechnical Engineering has provided the development of
innovative solutions to complex Civil Engineering problems.
This proves its technical capacity to face new challenges.
However, besides its well known evolution, the Civil
Engineering is yet pointed out as remarkable raw material
consumer and one of the leading waste generators in our
modern society. Nowadays, construction and demolition waste
(CDW) became a complex problem to government authorities
due to its economical and environmental impacts.
In this scenario, some aspects related to growth of cities and
to the need for adoption of sustainable development concepts
may threaten the technical and economical advantages of
reinforced soil structures: i) lack of good quality backfill
material near to site construction and ii) compliance with
environmental laws, which became more strict with respect to
exploitation of new raw materials deposits. Bearing in mind
these aspects, the use of recycled construction and demolition
waste (RCDW) in reinforced soil structures appears to be an
interesting proposition.
In order to investigate this proposal, two instrumented full-
scale wrapped face geosynthetic reinforced walls were
constructed using RCDW as backfill material.
1.1
RCDW geotechnical characterization for use in
reinforced walls
The Brazilian Environmental National Council (CONAMA), in
its Resolution 307/2002, states that wastes generated in “[…]
site preparation and excavation […]” are classified as
construction and demolition waste (CDW). Due to this, huge
amounts of soil stockpiles can be found in some Brazilian
recycling plants. According to the Construction Waste
Collecting Association (2011), in Brasília (capital city of Brazil)
approximately 70% of mass of municipal solid waste consist of
CDW. According to Santos (2011), approximately 65% of mass
of the recycled construction and demolition waste (RCDW)
produced in Brasília is composed of soil. This fact reveals an
interesting perspective to the use of RCDW in geotechnical
works.
Santos (2007), in order to evaluate the potential use of
RCDW in geosynthetic reinforced walls, carried out a
laboratory testing program focused on geotechnical
characterization and pH tests. Furthermore, pullout tests with
geogrids were performed using clayey sand [typical soil from
the southeast part of Brazil] and sand obtained from a local
supplier. Clayey sand was chosen in order to compare the
behavior of RCDW to others materials. The sand material was
compliant with FHWA recommendations for backfill materials.
