An interesting application in the Cifa range for casting the ballasts of the gate housing caissons of Venice's Mose project

The Mose project is a vast intervention plan to protect Venice and its lagoon implemented by the Italian State (Ministry of Infrastructure and Transport, Provveditorato Interregionale per le Oper Pubbliche del Triveneto) through the Venezia Nuova Consortium. This Consortium consists of national and local construction and engineering companies. A vast programme of activities to protect the city against flooding and high tides and rebalance the ecosystem of the lagoon. The mobile flood barriers at the lagoon inlets represent the latest and most important piece of this great work of coastal and environmental protection.

The system consists of 4 mobile barriers at the inlets that connect the lagoon with the Adriatic sea. These barriers will operate by blocking high tides, which could cause floods. They will remain invisible on the seabed the rest of the time. There will be 2 rows of mobile gates at the Lido inlet, 1 at the Malamocco inlet, and 1 at the Chioggia inlet for a total of 78 gates.

The Lido inlet measures 800 m and is twice the size of the other two. Moreover, it has two channels with varying depth (Lido Treporti north and Lido San Nicolò south). This is why it required two rows of mobile gates connected by an artificial island located at the confluence of the two channels.

We had the chance to visit the impressive construction site (close to completion) at the Malamocco inlet, hosted by Grandi Lavori Fincosit (which manages the construction sites at the Malamocco and Lido San Nicolò inlets) and Federico Zanetti (in charge of the transport and placing of concrete). The Malamocco inlet is 400 metres wide. Here the lock (which will allow cargo ships to transit when the gates are up) and all the technological buildings (which will have a large number of photovoltaic panels on an aluminium roof) are almost complete. Currently, they are working on the ballasts of the gate housing caissons.

This intervention will require the casting of over 22,000 cubic metres of concrete (over a period of six months). An extraordinary endeavour, not only in terms of the quantities involved but also, and more importantly, because of the logistic and technical difficulties of the casting site. Zanetti has used an average of ten operators, four in the tunnel (one at the trailer-mounted pump, and the others along the route), a pump technician for the K39H, four concrete mixer drivers, and a loading shovel driver for loading the aggregates for the production of concrete.

The ballasts will be rest at the bottom of the Malamocco inlet, at a depth of over 20 metres. Concrete has a long way (in some cases almost 440 metres) to go before reaching its destination.

An "ordinary" casting solution would not have been enough to overcome these technological barriers. This is why Federico Zanetti srl, the company in charge of transporting and placing the concrete (which had already made the ballasts of the San Nicolò inlet over a period of six months), has come up with an interesting solution approved and supported by GLF.

The project was developed with Cifa's design and technological contribution, supported by S2 Truck Service, Cifa's local Assistance Centre (which took care of the weight bearing structures). The project consists of a true pumping chain, which starts with the Cifa K39H Carbotech truck mixer pump (which ensures a maximum output of 160 m3/hour, with a maximum vertical casting height of 38.1 metres and a maximum horizontal distance of 33.8 metres), which Zanetti has purchased from S2, and continues with a Cifa DNA1.0 helical twin shaft mixer, a Cifa PC797E trailer-mounted pump with an electric motor, which pumps the concrete into the distribution piping towards the caissons to be filled.

Do you think that's difficult? Absolutely not! The truck mixer pump works on a barge anchored near the Malamocco channel and is fed by the truck mixers, which come from the nearby concrete production plant and cover the last stretch on a barge. This is why, in agreement with Zanetti, the Cifa technicians have decided to place a mixer between the machine and the trailer-mounted pump. The mixer keeps the concrete well-mixed preventing it from hardening, and serves as a "lung" (it has a capacity of one cubic metre) to prevent dangerous unwanted interruptions of casting operations in the event that the truck mixers delay their arrival.

The pumping pressure was a crucial factor. It was essential not only to keep it high (up to 80 bar on the concrete), but also to ensure its continuity. This led to the choice of the Cifa PC797E trailer-mounted pump, which serves as an additional pumping station. The pump pushes the concrete from the bottom of the access well along the main pipes (5.5'' diameter) in the service duct (one of the two parallel ones that run under the Malamocco channel) to the branches (4.5'' diameter), which lead to the ballasts to be filled. Insufficient or variable pressure values would have compromised the quality of the concrete or, even worse, they would have made it harden in the pipes, with consequent downtime and additional maintenance and restoration costs.

Another important aspect was given by the fact that the truck mixer pump works on the surface, while the mixer and the trailer-mounted pump are installed, one on top of the other, in a metal beam tower, which reaches 23 metres below sea level. S2 Truck Service has created the entire metal structure in its workshop in Villorba, testing its features with a complete pre-assembly, Cifa machines included. Once satisfied, Paolo Corso, the owner of S2, assisted Federico Zanetti in the assembly, inspection, and various pumping tests of the pumping solution.

As Cifa's Assistance Centre for North-Eastern Italy, S2 Truck Service has supported Zanetti during all pumping operations, and was always ready to step in the event of emergencies, replacement of malfunctioning components, or additional requests.

Machines, technical support, tailor-made solutions, Cifa has given all its best for this exceptional work. But there's another benefit to point out. Zoomlion Capital, the finance company owned by the Chinese group that owns also the Senago-based company, has financed Federico Zanetti srl not only for the machinery, but also for all the materials and processing required for setting up the structure. This way, the concrete transport specialist had only one thing to worry about: processing and delivering the concrete on-site to Grandi Lavori within the set timeframe. And Zanetti knows how to do that well, as all the timeframes for the supply were met.

The importance of high-quality partners

Interview with Federico Zanetti, owner of Federico Zanetti srl

"Support in the construction site is essential for us. The machines have to work for 8 to 9 hours a day, every day, for the entire casting period to meet the timeframe required by the client. We need reliable machines and Cifa certainly guarantees that. But we also need a supporting structure that can intervene promptly to minimise any downtime. I must say that Paolo Corso with his S2 Truck Service was of great help to make us work without any worries. Our company was founded in 1998 - continues Mr Zanetti

– with a fleet of truck mixers and mixer pumps. Over time, we have specialised in the transport and casting of concrete on-site and complex sites, both in the infrastructure and in the industry sectors. Today, there are 23 of us, and we work all across North-Eastern Italy. We have been working with Cifa for quite a while now. We have several Cifa trailer-mounted pumps, namely the K39H Carbotech (its last two sections are made of carbon), which we are using here for the Mose project, one K41H and one K47 XRZ. We have an excellent relationship with Cifa, and we are very happy to collaborate with them. The K39H, which we are using here for the Mose project, has already pumped for over 700 hours, and we have never had any particular problems."