Chemical Causes of Concrete Degradation

Submit Manuscript | http://medcraveonline.com attacks or stresses to which it is subjected, as well as various actions such as wind, rain, cold, heat, the environment while maintaining its aestheticism. It must satisfy, at a constant level, the needs of users during its service life. The notion of durability of a structure results in a set of technical specifications based on direct or indirect test methods, experience and recommendations for implementation, manufacture and maintenance. In fact, it is now possible to define sustainability objectives and to choose concrete characteristics precisely according to the aggressiveness of the environment in which the structure is located and to optimize its characteristics in order to adapt them to the duration desired service. The specifications concern the nature and minimum cement dosage, the minimum compactness, the maximum value of the Water/ Cement ratio, the minimum encapsulation of the reinforcements and the maximum chloride content in the concrete. The diagnosis of the state of conservation of a reinforced concrete structure makes it possible to characterize the origin and the extent of the possible disorders. In general, this diagnosis follows a detection of disorders, but it is also requested in various settings, such as renovation work or regular inspections. A prior inspection of the structure makes it possible to make assumptions about the possible causes of the disorders, and thus to specify the operations to be performed, taking into account the operation of this structure. The mechanical functioning of the different parts of a structure is a very important point to consider. Indeed, if the phenomenon that causes deterioration of the base concrete is not controlled or if its diagnosis is incorrect, it is very likely that this mechanism of degradation also affects the repair concrete. An incorrect identification of the source of the problem then results in costly, unsuccessful and especially recurrent interventions, which is certainly not interesting from the point of view of the sustainability of the works and budgets, sometimes limited, managers. Concretes can be confronted with chemically aggressive environments that cause their degradation such as carbonation, alkali-reaction and sulphate reactions [1,2]. The natural concrete carbonation depends simultaneously on the materials’ characteristics and the surrounding environment and it is associated with CO2 diffusion in concrete. it causes the reinforcement de passivation leaving the steel susceptible to corrosion [3-6]. The most common repairs to concrete structures are either wet or dry process concrete, or formwork with or without concrete overlay, or more recently self-leveling concrete. This innovative technique is currently the subject of all intentions. This material is so fluid and lends itself to the most complex forms without being vibrated. The repair of a concrete element that usually involves two very different materials, where the placement of a young concrete on an older concrete support causes different types of problems, both physico-chemical and mechanical, related to the broad compatibility of the two materials in contact.