Soil corrosion of the AISI1020 steel buried near electrical power transmission line towers

Soil corrosion of carbon steel samples buried up to hundred days close to a high voltage power transmission line tower was examined by weight loss vs. time. A higher weight loss was observed if the samples were electrically connected to the tower than if they were not. This was attributed to the influence of alternating current (AC) signals induced in the soil by the transmission line. This field study showed for the first time the influence of the AC power line on the buried structure of the tower, while other studies so far were focused only on AC corrosion of cathodically protected coated pipelines, running parallel to the transmission line. An improved method was used to measure weight loss by descaling in Clark solution. The new method substitutes discontinuous measurements, proposed in the ASTM-G1-90 standard, by in situ measurements of the weight loss during descaling, using a computer controlled microbalance

Semi-empirical models to describe the absorption of liquid water in natural stones employed in built heritage before and after the application of water repellent treatments

This study aims at validating an easily implementable and effective methodology to simulate the capillary imbibition rate of porous building materials, with special attention to stones employed in historical architecture. Two models selected from the literature are discussed from both a theoretical and practical viewpoint and their effectiveness in describing the imbibition process is evaluated on a large set of water absorption data of four different natural stones. It is shown that these models can be used in a predictive way to calculate the sorptivity of stones with fairly good approximation. Furthermore, they may represent a useful tool for the study of porous materials of built heritage, since, contrary to standard tests for sorptivity determination, they only require small samples to determine the pore size distribution and the maximum water saturation of the investigated materials. Finally, it is shown that the same models can also be used to simulate the reduction in water absorption after the application of water-repellent products, affording some insight into the protection mechanism and the criteria that determine the performance of protective treatments

Corrosion induced metal release from copper based alloys compared to their pure elements

Despite numerous studies on atmospheric corrosion of copper and copper based alloys, the corrosion induced release processes of individual alloy constituents suffer from significant knowledge gaps. This investigation comprises metal release rate measurements of copper, zinc and tin from some copper based alloys including brass (20 wt-%Zn) and bronze (6 wt-%Sn), and their pure alloying metals, copper, zinc and tin. Data have been generated during a 2,5 year urban field exposure in Stockholm, Sweden and parallel laboratory investigations in a specially designed rain chamber using artificial rain. Brass shows significantly lower annual release rates of both copper and zinc compared to pure metal sheets of its alloy constituents. Zinc is preferentially released compared to copper. Dezincification of brass occurs both at field and laboratory conditions, a process influenced by rain characteristics. Alloying with tin does not largely reduce the release rate of copper from bronze compared to pure copper. No measurable amount of tin is released from the bronze surface

Corrosion-induced release of Cu and Zn into rainwater from brass, bronze and their pure metals. A 2-year field study

A 2-year field study has been conducted in an urban environment to provide annual release rates of copper and zinc from brass (20 wt% Zn) and copper and tin from bronze (6 wt% Sn) compared to sheets of their pure alloy constituents, copper and zinc. Despite relatively low nominal bulk alloy content, substantially more zinc was released from brass compared to copper. Both metals were released at a significantly slower rate from the brass alloy, compared to the pure metals. The proportion of release rates of copper and zinc from the alloy differed significantly from their proportions in the bulk alloy. Bronze showed relatively constant release rates of copper, being similar to that of pure copper sheet. The release of tin from bronze was negligible. The results clearly show that alloys and the pure metals behave very differently when exposed to rainwater. Accordingly, release rates from pure metals cannot be used to predict release rates of individual constituents from their alloys. Generated data are of importance within REACH, the new chemical policy of the European commission, where metal alloys erroneously are being treated as mixtures of chemical substances

Corrosion-induced metal release from copper-based alloys compared to their pure elements

none4noneS. GOIDANICH; I. ODNEVALL WALLINDER; G. HERTING; C. LEYGRAFGoidanich, Sara; I., ODNEVALL WALLINDER; G., Herting; C., Leygra

A study of organic substances as inhibitors for chloride-induced corrosion in concrete

Chloride-induced corrosion of carbon steel reinforcement is the most important cause of premature failure on reinforced concrete structures. Among available methods, corrosion inhibitors offer a simple and cost effective prevention technique, primarily to prevent and stop chloride-induced corrosion. Nevertheless, performance of commercial inhibitors is only partially satisfactory. This paper deals with a basic study on the inhibitive action of organic substances toward chloride-induced corrosion on carbon steel rebar in alkaline environment. The effect of aminic and carboxylic groups was investigated through electrochemical potentiodynamic polarisation tests in simulating concrete pore solution in the presence of chlorides, to ascertain inhibitor effectiveness to increase pitting potential. Results are discussed taking into account the most likely mechanism of inhibition, in relation to the functional group of tested organic compounds