CONJET ASSISTS WITH REPAIRS TO ITALIAN VIADUCT

2009-07-02 — The multi-span reinforced concrete viaduct at Torano,
about 100 km east of the Italian capital Rome, is a
major structure on the main E80/A24/A25 Autostrada
crossing central Italy. The Viadotto Fiume Salto was
opened in the late 1960s, but the use of de-icing
salts during winter months has since caused
considerable calcium chloride damage to the structure
forcing the Italian Highways Authority and the
Autostrada di Parchi’s owner Toto S.p.a. to carryout
extensive repairs. The renovation, funded by revenue
from tolls, is expected to cost around €5M and is
focusing on the piers and main joints in the concrete
deck using the high pressure water jetting technique
of hydrodemolition to remove the calcium chloride
infected concrete.

Specialist hydrodemolition contractor C.P.L. 2000
S.r.l., in joint venture with Edil C.R.R. and Global
Klima S.r.l. and working for Toto, is using a Conjet
322 Robot hydrodemolition machine and Conjet Powerpack
bought specifically for the repair from Conjet’s sole
Italian dealer Roald di Codecasa & C.s.n.c based in
Milan. “This is a major bridge repair project and
hydrodemolition with the Conjet Robot is the only
method of removing the damaged concrete,” says C.P.L.
2000 S.r.l president Angelino Rinaldi. “Using very
high pressure jets of water to remove only the poor
concrete does not cause any damaged to the good
concrete left behind and if necessary it also takes
away concrete from below the reinforcement, which is
also cleaned of any rust. Using breakers would have
taken so much longer and also caused damage to the
good concrete left behind. Hydrodemolition with the
Conjet Robot also has the advantage of producing a
very rough surface, which gives a good bond for the
new concrete to key onto.”

The viaduct carries the busy dual two lane E80/A24
Autostrada across a narrow valley skirting to the
south of Torano and just before the E80/A24 forks
northeast towards L’Aquila and southeast onto the A25
to Pescara. The bridge deck is supported on 12 pairs
of reinforced concrete hollow piers up to 40 m high
and spaced at intervals of about 42 m across the
valley. The individual piers are spaced at about 11 m
centres and each one is topped with its own transverse
crosshead, which in turn supports longitudinal precast
concrete beams for each carriageway deck.

The main focus of the hydrodemolition repair is on the
octagonal shaped piers and their crossheads where the
de-icing salt has leaked down from the deck above. The
calcium chloride attack on the concrete is
inconsistent with a patchwork of damaged areas over
the surface of the 24 piers totalling about 380 m2. In
many instances the de-icing salt has seeped deep into
the concrete and the resulting corrosion of the
reinforcement has pushed the concrete off and exposed
the reinforcing to further corrosion from the
elements. C.P.L. 2000 S.r.l concentrates on one pair
of piers at a time and successfully uses a special
purpose built rack and pinion climbing platform
designed and built by Safi, which gives the Conjet 322
Robot unrestricted working access to all faces on each
set of piers. The Conjet 322 Robot is connected to a
Conjet Powerpack delivering clean fresh water at a
pressure of about 1,300 bar and flow of 200 litres/min
and is removing concrete generally to a depth of 30mm
to 130mm. In some instances maximum removal depth has
been as high as 180 mm, but the average on the project
has been between 70 mm to 80 mm. “We bought the Conjet
322 Robot specifically for this project and has been
operated by Yamadu Konate and Vittorio Triuzzo. The
322 has been a very good machine and I can’t see how
we could have done the job without it,” says Angelino
Rinaldi.


Cont/



After C.P.L. 2000 S.r.l has finished concrete removal
from one set of piers the company moves onto the next
pair using a separate, but identical Safi working
platform. Another contractor in the joint venture then
follows on using the first platform to spray steel
fibre reinforced concrete on the patches, which are
levelled and float finished by hand. The entire
sequence is repeated on all 12 pairs of piers. C.P.L.
2000 S.r.l is also using hydrodemolition with hand
lances to remove the damaged concrete from the main
joints on the bridge deck and also directly underneath
the longitudinal beams supporting the deck.

Conjet was involved at the early stage of the project
and assisted CPL 2000 S.r.l. in selecting the right
type of platform they would need on the tall piers.
Conjet considered the space the robot would require to
work in an unrestricted manner and maintain high
production during the concrete removal process. CPL
2000 S.r.l. is using three platforms and after
concrete removal with the Conjet Robot they are also
used for the placement of fresh concrete.

To complete the concrete restoration the repaired
structure will be finished off with a final coating of
protective paint to prevent possible future attack
from de-icing salt. The repairs started in June 2007
with the hydrodemolition following on three months
later in September. The project shut down during the
winter months from December to March and restarted in
spring of 2008 and finished on schedule at the end of
November.

For further information please contact:

Lars-Göran Nilsson or Carl Strömdahl

Conjet AB
P.O. Box 507
S-136 25 Haninge
Sweden.

Tel: +46-8-556 522 40
Fax: +46-8- 556 522 60
E-mail: conjet@conjet.se
Internet: www.conjet.com

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