Dr. Mahipal Burdak
Abstract: The concrete structures are built keeping in mind the strength aspect. The long term durability is normally sidelined. The situation has been complicated by some types of aggressive action like Sulphate attack, abrasion, frost action, Alkali Silica Reaction (ASR), corrosion due to carbonation & chlorides, etc. The impact of these effects on structural performance & strength is less well defined, researchers have tended to take a general approach based on risk analysis & probabilistic methods. The basis for rational decision making is not clear. Is the priority to prevent or at least slow down the deterioration rate or is it to repair, upgrade, strengthen or rebuild What is the most effective action & when should it be taken to optimize the balance between Whole Life Costing (WLC) & maintenance of satisfactory technical performance In response to this need, the development of repair & preventive measures has become a growth industry. Quantified feedback on the performance of concrete repair systems is inadequate. There exist various individual case studies involving damage assessment & giving reason why a particular remedial action was selected. However, it is tough to have any general guidance or even a common denominator to assess alternative options. Owners attitude appears to be vital, as indeed is cost, in the absence of quantified data. In this paper, an attempt has been made to review the work carried out by researcher Tilly in connection with the field performance of repair systems for bridges & other structures in European countries. The repair systems included patch repairs, coatings, crack injection, sprayed concrete, electro-chemical & strength restoration. It is difficult to deduce any generally acceptable life expectancy while adopting a particular repair system. This shows that available guidelines, while improving all the time, are either not being applied properly or are still deficient in some areas.
Keywords: Quantified feedback, deterioration, poor workmanship, incorrect design, etc