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

Expert appraisals
Diagnosis of concrete
Caring for the A4 motorway
Lamination damage
in concrete.
75
Five bridges on the A4 motorway are exhibiting lamination
damage and concrete decay. The Physico-Chemical
Behaviour of Materials Group (CPDM) was asked by the
motorway concessionary company SANEF to determine
the causes.
The CPDM applied a number of laboratory investigation
techniques to identify the concrete formula that was used
during construction and establish the state of conservation of
the concrete by identifying the presence of substances that
are liable to cause damage.
The results showed that the concrete in question had been
damaged from scaling caused by a combination of several
factors: the action of freeze/thaw cycles and de-icing salts,
the high porosity of the concrete, failure of the waterproofing
complex and the use of highly frost-susceptible aggregate.
In view of the advanced state of the process, SANEF decided to
repair the affected bridges by demolishing and rebuilding the
affected parts and redoubled its surveillance of structures with
the same design. In this connection, the CPDM has developed
a simplified inspection procedure for managers to check the
state of the concrete of all the uninspected bridges in the stock
which were built during the same period.
@ CONTACTS
loic.divet@ifsttar.fr
stéphane.lavaud@ifsttar.fr
A structure after repair.
ANNUAL REPORT 2011 ifsttar.fr