french institute of science and technology for transport ... - Ifsttar

Research orientation R_Durability, hazards and nuisances
Embedding concrete
Nondestructive tests
The ageing of the national stock of structures makes it
vital to evaluate the condition of embedding concrete.
The AI (Testing and Imaging) Group is involved in several
research projects that aim to develop mechanical,
electromagnetic and electrical nondestructive survey
techniques.
The group’s most recent work has identified the linear
trends that link composition and condition parameters
(such as porosity, degree of saturation, compressive strength,
chloride content, etc.) to physical measurements and observations.
The research has shown that physical measurements are sensitive
to most of the parameters that describe concrete, but to
highly variable degrees, and some parameters may be confused
with measurement biases. The physical measurements
include electromagnetic and mechanical waves. The first of
these mainly depend on the volumetric moisture content and
nature of the aggregate and the second are governed by the
material’s compressive strength and Young’s modulus.
The different results also complement each other, as it has
been observed that when several different measurements are
made on a given homogeneous mixture (among those that
have already been tested) it is possible to find the initial parameters
from each.
The relationships in question are currently being validated
in the framework of the ACDC and EVADEOS projects which
are investigating their recalibration according to the type of
structure which is tested and how gradients affect this type of
non-destructive measurement.
@ CONTACT
xavier.derobert@ifsttar.fr
Characterization of embedding concrete.
47
POLESUR
Preserving and managing urban soils
In order to limit urban sprawl, local authorities are increasingly
faced by the need to redevelop sites that have
potentially been contaminated by industrial and artisanal
activities. To these concerns are added the risk that pollutants
may be transferred into the soils as the result
of the implementation of urban stormwater infiltration
techniques.
The consortium has now joined up with IRSTV (Institute for
Research on Urban Sciences and Techniques) as a first step
towards the creation of a national centre of expertise on urban
soils in the Pays de la-Loire region.
@ CONTACT
beatrice.bechet@ifsttar.fr
In the Pays-de-la-Loire region, the desire to improve the
protection and management of urban soils has prompted the
Region to support for the POLESUR project (Pollution of water
and soils in urban areas). This programme, which was backed
by the region’s largest consortium in the area of urban soils
(IFSTTAR, BRGM, École Centrale, École des Mines, Université,
CSTB, Agrocampus Ouest), lasted 4 years and ended with a
seminar on 7 and 8 December 2011.
The results, which bring together knowledge about pollutants,
the infiltration characteristics of water retention ponds and the
water treatment capacities of floating marshes, provide answers
to concerns about the infiltration of stormwater and the environmental
impact of derelict urban land. The project applied
a multi-scale study methodology to evaluate the contaminant
plume from an old landfill site for household and industrial
waste in Nantes.
A general view of the
Prairie des Mauves landfill
site (Nantes) with the pit
excavated in the stored
waste by a mechanical
digger. A layer of waste from
the 1980s, shown by the
blue bags, is clearly visible
at a depth of 3 metres.
ANNUAL REPORT 2011 ifsttar.fr