CELESTE, A. B.; http://lattes.cnpq.br/9693479816689582; CELESTE, Alcidney Batista.
Résumé:
The Low Impact Development (LID) approach to rainwater management in
urban areas has been gaining interest from the international community due to the
growing urbanization of developing countries, the sealing of urban soil and, mainly, the
changes in rainfall patterns caused by climate change. However, debates due to the
lack of consensus on its conceptualization reinforce the creation of blind spots in
practice. This disconnect between conceptualization and practice is a manifestation of
the way in which dominant visions of urban development are imposed from the top
down. Despite the criticism of LID, this research studied one of its most traditional
techniques, the permeable pavements. The aim was to select designs for porous
asphalt mixtures used as a surface coating for permeable pavements, based on
mechanical and functional criteria. Fifteen porous asphalt mix designs were conceived,
combining five different grain sizes and three different binder contents. Among five
gradings, three were from national ranges and two from international ranges. In the first
stage, the mechanical parameters studied were restricted of tensile strength, resilience
modulus, cantabro loss mass and induced moisture damage tests. In the second stage,
the functional performance was assessed with permeability, infiltration and water
retention tests. The ponding time of the pavement surface was also evaluated. In the
third stage, specific optimization problems, such as reconciling conflicting mechanical
and functional objectives, were designed in different scenarios. Each problem was
solved using an optimization model based on the concept of solution dominance, which
consists of choosing one or more optimal solutions with the best trade offs between the
multiple objectives to be optimized. Each problem was solved by selecting the most
suitable mixtures for each proposed scenario. Some boundary conditions helped
formulate problems with conflicting objectives involving permeable pavements, such as
traffic levels, climate, temperature and road drainage conditions. Among the results of
the mechanical tests, meeting the minimum tensile strength was an almost systematic
problem, while stiffness was more influenced by the grain size of the mixture and mass
loss by the binder content. With regard to moisture susceptibility, the mixtures obtained
satisfactory responses, mainly due to the type of binder used. In terms of functional
performance, the communicating voids in the mix were directly proportional to the
permeability and, together with the grain size and binder content, influence its water
retention capacity. The binder content and granulometry also influenced the infiltration
rate and, consequently, the ponding time, but it is the thickness and anisotropy of the
other pavement layers that determine how quickly they reach their potential infiltration
capacity, which directly impacts their ponding time. As for the results of the
optimizations, not just one, but a set of mixtures can be the solution to the same multiobjective
problem and the decision depends on the boundary conditions. In general,
porous mixtures with higher binder contents and maximum aggregate diameters of 12.5
mm stood out from the other mixtures available in the decision space.
