Prepared by B. Elsener with contributions
Corrosion of steel in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The majority of concrete structures perform well even after a long period of use in normal environments. However, there are various reinforced concrete structures important for our infrastructure, especially bridges and buildings, which exhibit premature damage due to environmental actions (EN 206). In contrast to mechanical actions (as load, wind, etc.) the environmental actions are not reversible and accumulate hazardous components (as e.g. chloride ions) in the concrete. A high percentage of the damages is caused by insufficient planning, wrong estimation of the severity of environmental actions and by bad workmanship and thus many of these structures need to be repaired after a short service life. In most industrial countries, repair and restoration of reinforced concrete structures today is nearly as important as new constructions. Due to the importance of the problem, RILEM set up an initial committee on reinforcing steel corrosion in 1960. A second committee related to the problem, TC 60-CSC ‘Corrosion of Steel in Concrete’, was established in 1980, presenting a state-of-the-art report in 1988 on the generally agreed knowledge about the processes causing corrosion and the corrosion mechanism themselves. RILEM TC-124 on Strategies for the Repair of Concrete Structures Damaged by Steel Corrosion published a draft recommendation in 1994, where the importance of condition assessment has been pointed out as the first step in the repair process. To ensure a sound decision on the type of repair work, it is essential to get first of all a thorough assessment of the condition of the structure, including the evaluation of: cause of damage or loss of protection degree and amount of damage expected progress of damage with time effect of damage on structural behaviour and serviceability. The acquisition of reliable information on level and rate of deterioration is done during regular main inspections relying on visual examination of the whole structure. If no reliable conclusion on the state of the structure or part of it can be obtained, an additional inspection (verification) including non-destructive testing has to be performed until the cause of damage is clearly identified. The text presented hereafter is a draft for general consideration. Comments should be sent to the TC Chairlady: Dr. Carmen Andrade, CSIC Instituto de Ciencias de la Construccion "Eduardo Torroja", Serrano Galvache s/n Aptdo 19.002, 28033 Madrid, Spain; Tel.: +34 1 302 04 40; Fax: +34 1 302 07 00; Email: andrade@ietcc.csic.es, by 31 December 2003.
Half-cell potential mapping to assess repair work on RC structures
Abstract Rational, cost effective strategies for the repair and rehabilitation of bridge components have to be based on reliable information on the level and rate of deterioration. Rapid, non-destructive techniques such as half-cell potential mapping can detect and locate the main cause of deterioration, the localized chloride-induced corrosion of the rebars, and thus, greatly improve the quality of condition assessment and repair works. After completing restoration suitable monitoring techniques should be made available to control its effectiveness and durability. This paper reports on the successful use and limitations of half-cell potential mapping as an assessment technique after completion of repair work. The examples presented and discussed include traditional repair (replacement of chloride contaminated concrete), electrochemical chloride removal (ECR), electrochemical realkalization (ER) and the application of surface applied corrosion inhibitors. It is shown that due to possible changes in resistivity and pH of the concrete pore solution induced by the repair work, a correct interpretation of half-cell potential readings after repair work requires precise knowledge on the mechanism of corrosion protection of the repair strategy, and a sound experience in half-cell potential mapping on RC structures.
Globalization and the Internationalization of Legal Education in the United States: An Annotated Bibliography
Globalization and its influence on legal education is a topic of growing interest to the legal profession and to legal educators alike. The first articles on the subject appeared in the mid-1990s, and the frequency of publications has been increasing ever since. This bibliography provides annotations to English-language law journal articles published between 1995 and 2008 that focus on the impact of globalization on legal education in the United States.