The Peer review has evaluated this group as Average
Different aspects related to degradation of metallic materials, reinforced concrete and masonry have been studied in order to improve the durability of constructions and industrial plants. The group is organized around three main topics: 1) Materials and durability for industrial plants 2) Modern and ancient mortar and concrete and durability of constructions 3) Materials for cultural heritage 1. The research activity of the last years has been focused on the study of corrosion in industrial plant, with special reference to production and transportation of hydrocarbons (since many years the research group carry out assistance to ENI group – exploration & production division for failure analysis and corrosion assessment). Degradation phenomena can arise both on the internal and the external side: fluid process may contain aggressive species towards metallic materials, i.e. chloride ions, CO2 and H2S (internal corrosion); metallic structures are exposed to natural environments (external corrosion): atmosphere, soil or seawater, where different prevention techniques (i.e. cathodic protection) can be adopted. In detail, the research project are: Localised corrosion risk evaluation of metallic materials for the petroleum industry in chloride containing environments by means of probabilistic models; - Corrosion of soil pipelines due to AC interference from high voltage transmission lines: while DC current interference is a well studied phenomenon, the mechanism by which AC affects the corrosion process is not yet completely understood; - Stress corrosion cracking of steels for long distance, high pressure gas transportation: high strength steels were compared with lower strength steels; - cathodic protection in soil and seawater: new reference electrodes (probes) for monitoring, protection conditions in severe exposure (deep seawater), galvanic anodes behaviour in different environments (soil and seawater), hydrogen embrittlement of titanium cathodically protected, - monitoring localized corrosion of prestressed wires by means of a new multi reference electrode system (European COST action 534); 2. The research activity have been focused on different aspects of durability of constructions. Corrosion of steel in concrete has been investigated in order to define the factors that influence its initiation and propagation and, thus, modelling the evolution of the phenomenon: influence of environmental factors and concrete mix on chloride threshold; - effect of DC and AC stray currents; - galvanic coupling phenomena; - protection of steel embedded in low-strength cementitious materials used for backfilling. Different preventative techniques have been evaluated in relation with the aggressiveness of the environment and the service life of the structure: - cathodic prevention and protection of structures in chloride bearing and carbonated concrete; - electrochemical chloride extraction; - stainless steel rebars; - corrosion inhibitors for prevention or repair; Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta” – Research Assessment Excercise 2003-2006 56 Inspection and monitoring of reinforced concrete structures: - new technique, based on the lateral ohmic drop, for the evaluation of the ohmic-drop-free potential in structures subjected to stray current; - fixed reference electrodes for monitoring of corrosion of steel in concrete based on activated titanium or stainless steels; - comparison of techniques for the evaluation of chloride content in the concrete; - electrochemical techniques of potential mapping and polarisation resistance. The study on durability of construction materials extends to other materials and degradation phenomena: - environmental effects on bonded composite materials (F.R.P.) used for strengthening of structures; - electro-osmotic phenomena in construction materials and practical applicability of dehumidification techniques in damp masonry. Study of new cementitious materials: - development of a light-weight, self compacting concrete; - development of a controlled low strength material with self-levelling properties to be used for filling of trenches and tunnels; - suitability of ashes from municipal solid waste (MSW) incinerators as mineral additions for concrete; - performance of conventional repair of reinforced concrete structures; - self-cleaning and antipolluting properties of TiO2-containing cementitious materials. The research group, in cooperation with laboratories of microstructural analysis (SAMM) and chemical analysis (LAC) of the same Department, carry out chemical-physical and microstructural characterisation of cementitious materials. 3. Materials for cultural heritage, including the following main topics: knowledge of materials and of materials’ pathology and durability; - inspection, diagnosis (also development of new non-destructive analytical tools); - developing and testing new materials for conservation; - evaluation and testing restoration strategies. Materials of interests are: metallic materials; ancient mortars and concrete; natural stones, traditional lime binders, painting materials, polymers for conservation.
Fabio Maria Bolzoni
Maria Pia Pedeferri