Chloride exposures represent some of the most aggressive conditions in which concrete structures are located., Approaches followed in most national standards in the provision of durability for these normally give guidance in terms of mixture limits (minimum cement content and strength grade and maximum w/c), concrete cover depth and in some cases, cement type. In addition to controlling these, there are other routes that can extend performance, which concentrate either on (i) extending time to corrosion ini- tiation, by minimising rates of chloride ingress (eg controlled permeability formwork, silane coating and waterproofing admixtures) or (iij limiting corrosion rates, once conditions are such that the process can occur (eg corrosion inhibitors and stainless steel). This paper assesses the chloride resistance performance (in terms of chloride diffusion rates, chloride content at cover depth and reinforcement corrosion rates) of both conventional (methods in national standards) and other means of achieving corrosion resistant concretes and establishes how the more novel routes may fit within the mixture limit chloride durability specification frameworks. The results from tests on site produced concrete and concrete in a coastal exposure are used to explore the specification route for one of the novel systems (CPF).

Corrosion of steel reinforcements in concrete structures is the most important cause of premature failure. To improve service life of concrete structures, corrosion inhibitors are often proposed and used to prevent chloride induced corrosion and carbonation corrosion. This paper deals with a laboratory investigation both in concrete and in a synthetic pore solution on the effectiveness of mixed-in commercial corrosion inhibitors to hinder corrosion initiation and propagation of reinforcements in concrete structures. The results of a laboratory research aimed at studying the effect of inhibitors added to the concrete mixture are discussed. Three organic commercial corrosion inhibitors and, by comparison, nitrite based inhibitors were added to fresh concrete in concentration suggested by the manufacturers. Experimental tests were carried out on reinforced concrete specimens with carbon steel reinforcement in chloride contaminated concrete (both adding chlorides directly in the mixture and penetrating the hardened concrete by means of ponding cycles). In order to study the inhibitors effect, the results, in terms of two electrochemical parameters, i.e. free corrosion potential and polarisation resistance, are compared with those obtained considering concrete specimens without inhibitors. For comparison purposes, results on some pure organic substances are reported, confirming data obtained on the commercial products. Some positive effects are achieved when both commercial products and pure substances were used at dosage rates higher than that recommended.

This paper deals with the examination of a 17-year-old corroded beam. First, the cracking map due to corrosion was recorded. Second, a flexural test was conducted to measure the residual mechanical behaviour and the load-bearing capacity of the beam. Third, the degree of reinforcement Corrosion was assessed by removing all the concrete surrounding the reinforcing bars, and fourth the total chloride content in the vicinity of reinforcement was measured. The chloride content measure and the distribution of corrosion along the beam indicated that the prediction of corrosion initiation in reinforced concrete members is highly dependant on the quality of the steel-concrete interface. By comparing the cracking map and the degree of corrosion of the beam, actual models reliability, predicting the degree of corrosion from corrosion cracks width, was checked. A comparison between the mechanical behaviour and the degree of corrosion allowed a separation of the influence of steel section loss and bond loss on the decrease in the stiffness and the load-bearing capacity of the beam. Comparisons with existing models were also carried out.

Polymeric surface protection systems can he a durable and potent method to lower the moisture content of the concrete and to improve its durability by inhibiting the penetration of aggressive substances through the surface as well as by limiting the corrosion rates. At the Institute for Building Materials Research in Aachen, ibac, in cooperation with BAM in Berlin comparative tests have been carried out on the long-term durability of selected classes of surface protection systems financed by the German Ministry of Transport. These systems were weathered naturally at two different locations in Germany as well as artificially in different climatic test facilities. Afterwards the mass and dimension changes of the polymeric films, adhesion strength, diffusion of chlorides and carbon dioxide, cross-cut and crack bridging behaviour have been investigated.

The built environment of the early 20" century, constructed mainly with rein- forced concrete present serious damage problems. Thus, the establishment for an appropriate damage assessment methodology, that evaluates the concrete durability and service life, is a neccessity. In this study, two buildings of the early 20th century, exposed to an aggressive marine environment are examined: the first is the spa at Kallithea in Rhodes, constructed mainly with reinforced concrete, and the other is the Bell tower of the Church of Saint John Prodromos in Simi, where reinforced concrete was used for repairs. A series of non-destructive Techniques (Fiber Optics Microscopy, ultrasound technique, determination of corrosion potential at the reinforcement and determination of concrete carbonation depth) along with Laboratory Techniques (Grain size distribution, Mercury Intrusion Porosimetry, X-Ray Diffraction, Thermal Analyses) were used. The obtained results revealed that the concrete is carbonated up to the reinforcement bars. The reinforcement has lost the bearing capacity after its 7th lifetime decade. In addition, the nondestructive techniques methodology gave satisfactory results and could be undertaken, for the damage assessment of the modern built environment exposed to aggressive environments (marine or urban).