Diagnosis and rehabilitation of real reinforced concrete structures in coastal areas A. M. Carvajal 1 , R. Vera* 2 , F. Corvo 3,4 and A. Castan ˜eda 5 A diagnosis and rehabilitation study of two reinforced concrete structures located in coastal areas in two different climates is presented. Building 1 was constructed in the north of Chile in 1949, at a distance of 600 m from the coastline, in a seismic zone. Cracks, steel corrosion, loosening of concrete cover and slab deformations have been identified. Building 2 was constructed in Habana City, Cuba, in 1973. It is located at ,100 m from the shore. The structure of building 1 shows severe localised damage: loosening of reinforced cover and intense reinforcement bar corrosion due to high deposits of sea salts. High chloride and sulphate content in the concrete mass, low compressive strength in walls and slabs, high level of steel corrosion and zones with the existence of rust instead of steel were reported. A structural rehabilitation project to ensure an increase in service life is not possible. On the contrary, in case of building 2, a possible rehabilitation procedure is recommended. Elimination of chloride contaminated concrete and the use of special mortar is an option, and electrochemical chloride extraction and incorporation of sacrificial anodes is another. An important conclusion is made: the use of chloride and sulphate contaminated aggregates is more dangerous than the penetration of these two contaminants from the external environment for buildings constructed in coastal zones. Keywords: Reinforced concrete, Low compressive strength, Coastal zones, Reinforcement bar corrosion, Chloride and sulphate attack, Durability Introduction Corrosion of reinforcing steel represents the major cause of degradation of reinforced concrete structures. It also involves a potential safety hazard because concrete pieces can fall from height due to reinforcement corrosion. The corrosion process leads to several combined effects: longitudinal cracking of concrete cover due to expansive corrosion products, steel cross- section reduction and the degradation of the steel– concrete bond. As a result of these effects, the service life and the load bending capacity of reinforced concrete elements become considerably reduced. 1–4 Premature deterioration caused by reinforcement corrosion is being reported in an increasing number of structures. In general, this corrosion is caused by the destructive attack of chloride ions penetrating the concrete by diffusion and/or other penetration mechan- isms, by incorporation into the concrete mixture, by carbonation of the concrete cover of the reinforcement or a combination of these. 5 The conclusions of the DURAR project ‘The influ- ence of environmental action on reinforced concrete durability: DURACON’, with the participation of 11 countries (Latin America, Spain and Portugal), and based on the exposure of reinforced and non-reinforced specimens in several microclimates, showed that in marine atmospheres, chloride content in the environ- ment is the most decisive factor when evaluating the probability of reinforcement corrosion. It is important to note that this project did not analyse the influence of aggregate contamination. 6–8 It is well known that the corrosion of the steel bars in reinforced concrete caused by the ingress of chloride ions is the most severe problem affecting the durability of concrete constructions, especially in coastal and marine environments; however, carbonation induced corrosion is probably more widespread when consider- ing all reinforced concrete structures. When the concrete cover is damaged by sulphate solution attack, which is commonly encountered in field constructions, chloride ion will rapidly access the surface of the steel bar embedded in the concrete. The attack of sulphates on concrete is due to two principal reactions: the reactions of Na 2 SO 4 and Ca(OH) 2 to form gypsum and the reaction of this gypsum with calcium aluminate hydrates to form ettringite. In addition, it is noticed that MgSO 4 1 Facultad de Ingenierı´a, Escuela de Construccio ´n Civil, Pontificia Universidad Cato ´ lica de Chile, Santiago, Chile 2 Grupo de Corrosio ´n, Instituto de Quı ´mica, Facultad de Ciencias, Pontificia Universidad Cato ´ lica de Valparaı ´so, Av. Universidad 330, Placilla (Curauma), Valparaı ´so, Chile 3 Centro de Investigacio ´ n en Corrosio ´ n (CICORR), Universidad Auto ´ noma de Campeche, Ave. Agustin Melgar s/n, Col. Buenavista, San Francisco de Campeche CP 24030, Me ´ xico 4 Instituto de Ciencia y Tecnologı ´a (IMRE), calle Zapata esq. a G, Vedado, Plaza, Ciudad de la Habana, Cuba 5 Grupo de Proteccio ´n de Materiales, Direccio ´n de Quı ´mica, Centro Nacional de Investigaciones Cientı ´ficas (CNIC), Apartado 6412, Ciudad de la Habana, Cuba *Corresponding author, email rvera@ucv.cl ß 2012 Institute of Materials, Minerals and Mining Published by Maney on behalf of the Institute Received 19 March 2011; accepted 2 June 2011 70 Corrosion Engineering, Science and Technology 2012 VOL 47 NO 1 DOI 10.1179/1743278211Y.0000000018