responsabili: Giorgio Gianighian

visiting professor: Yongkang Cao, associate professor

Shanghai Jiao Tong University, School of Naval Architecture, Ocean and Civil Engineering (NAOCE). PRC;

Director of the International Research Centre for Architectural Heritage Conservation (IRCAHC)

presenza: 3 mesi - da aprile a luglio 2014

durata: 12 mesi 


termine previsto: 31 dicembre 2014


finanziamento:  15.000,00 euro


tipologia: call 2013 Dppac

fonte finanziamento: call 2013 Dppac – Linea di finanziamento 2 “Sostegno dell’attrattività internazionale”

descrizione del progetto di ricerca

The foundation continuous plinth of the Venetian buildings all over the city is not waterproof, but absorbs water from the ground and, through the phenomenon of raising damp, reaches the first floor beams.

In addition, in buildings located along canals and embankments (even at some distance away from open water) walls come into contact with water. With increasing frequency and a broader tidal excursion, brackish waters penetrate the building fabric, Thus humidity moves further upwards within the walls and compromises greater sections of walls as well as architectural elements anchored to them.

Higher water level now reaches above the barriers to humidity, both historic measures like the regolon, which is an Istria stone barrier inserted over the foundations, as well as measures taken last century starting with “healthy, economical, popular” housing of the late 19th to mid 20th centuries, with a layer of asphalt at what was then considered a safe height. Also new barriers made in lead or fibreglass or

impregnated chemicals tend to be superseded by water levels, not necessary only the exceptional tide events.

The physical problem for the walls occurs in the “wet‐dry” zone. Where the walls are permanently moist, the salts do not crystallize and the phenomenon of fracturing brickwork and cement/mortar does not occur, unlike the strip where there is periodic drying out.

Increasing frequency of higher tides does not only affect the walls but also other elements of Venetian buildings such as window and door frames, metals and reaches the ends of the ceiling beams on the ground floor as well, especially in the lower lying areas of the city. The phenomenon needs to be scientifically studied throughout the city.

For low lying buildings, tidal excursion also causes modification of the ground (different equilibrium between solid and liquid parts), due to compaction of particulate matter and dispersion into the canals – and consequent lowering of the ground level, which causes structural weakness.

It must also be considered that building foundations and embankment walls are not impermeable, as said before, and therefore particles pass through the mortar joints between brick and brick. The latter are then dispersed into the canal, especially in occasion of canal drying, in order to remove the deposited mud, and for the very low tides. Furthermore the ground underlying paving, both external (masegni or herringbone brickwork) as well as internal, is subject to variations in water level according to the tidal cycle and to a consequent lowering of the ground level, which causes structural damages to the buildings.

These phenomena of ground loss through migration need to be examined with new laboratory testing to verify, for example, the permeability of different materials and foundation structures, carrying out verifications of water levels via the installation of piezometers.

In conclusion, with the increase in average water level, there is evident worsening of the conservation state of materials and structures of Venetian buildings, albeit still to be explored in terms of total extension.

The quantification of all the phenomena needs to be tested, analysed etc. in order to plan a protection system that could reduce tidal excursion, limiting both the peak and trough water levels.

In order to finalise a protection project we intend to analyse five Venetian important palaces, such as Page 25 of 1332: Ca’ Loredan Farsetti ‐ byzantine; Ca’ Garzoni e Moro – gothic; Ca’ Gussoni – Renaissance; Ca’ Pesaro – baroque; Ca’ Corner della Regina – 18th c., which have been already scientifically surveyed and tested (metric and topographic survey, geotechnical core drilling and tests, hydrometric and salt analyses, investigations on the masonry, magnetometer and endoscopic surveys, etc). Now we have to compare the previous data with the new ones we will obtain, in order to understand the differences, which can lead to increase the decay of masonry and their connections with the floors, causing the worsening of the bearing capacity of the palaces.

The same methodology of research will be carried out on five important heritage listed buildings on the Shanghai Bund (i.e. the embankment/quay), such as The Chongsi Building of Xuhui High School ‐ 1918; The Shanghai Club Building – 1910; The Customs House – 1927; The Sassoon House – 1929; The Shanghai Electric Power Building – 1930s.

The buildings are of course much more recent than the selected Venetian ones, but many of the building materials are similar. However it will be interesting to understand how the damp and salts are attacking the traditional materials but also the reinforced steel structures.

The investigation examples may vary according to the most accessible data already available, maintaining the same research methodology in both study cases.

By the end of Professor's Cao research stay in Venice, we will organise an international seminar to discuss the first results of the research and its results in this joint Sino‐Italian research project. During the research, which will last for 24 months, the second part of it will deal with the intervention techniques and conservation projects. It’s very likely that at the end the research will produce a second volume by Shanghai Jiao Tong University Press, in 2015.

This research has no scientific precedent: it will analyse how both the heritage clusters under study incur a twofold danger: on one side the raising of brackish waters is causing decay and structural instability, while on the other side the raising humidity, an older but equally dangerous phenomenon, makes the conditions of the buildings even more risky.

The Shanghai Jiao Tong University Press by December of 2014 will publish all the papers discussed in Venice, with other relevant documents originated from the common research – in Chinese and in English.

descrizione del progetto didattico

Seminario: “Water levels and degradation of heritage buildings in Venice and Shanghai: comparative case studies”, destinato a Professori e ricercatori Iuav, collaboratori alla didattica, dottorandi di ricerca, studenti nostri e di altre università veneziane – e cinesi per la seconda fase del progetto.