Location

University of Leeds

Event Website

https://engineering.leeds.ac.uk/info/201479/conferences/270/sixth_international_conference_on_durability_of_concrete_structures_icdcs2018/4

Keywords

chloride, corrosion, fly ash, marine, silica fume, slag

Abstract

This paper presents a summary of data from wide range of concretes following periods of marine exposure ranging up to 25 years. Data are presented from more than 100 different concrete mixtures. The various types of concrete include fibre-reinforced concrete (FRC), ultra-high performance concrete (UHPC), concrete with a range of supplementary cementing materials (SCM such as fly ash, slag, and silica fume) and replacement levels (e.g. up to 58% fly ash and 80% slag), lightweight-aggregate concrete (LWAC) and concrete containing alkali-silica reactive aggregate. Testing included measuring chloride concentration profiles, electrochemical corrosion measurements (for steel-reinforced concrete), and various electrical and mechanical properties, in addition to the examination of the microstructure. The data invariably show the importance of the binder type in terms of resistance to chloride ingress and the protection conferred on embedded steel reinforcement, however, the overall performance of SCM concrete was equivocal as high replacement levels were observed to lead to increased surface deterioration (scaling) in some cases. The performance of UHPC was exemplary with little significant chloride penetration and no evidence of surface deterioration after up to 20 years exposure and an estimated 2,000+ freeze-thaw cycles. Expansion (and cracking) due to alkali-silica reaction was observed to be reduced by seawater exposure but, perhaps more significantly, render air-entrained concrete highly susceptible to freeze-thaw damage when the expansion exceeded a certain threshold value. The data are discussed in terms of code requirements and the need for appropriate performance testing. The importance of long-term monitoring of concrete on exposure sites is also discussed.

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The Performance of Concrete in a Marine Environment

University of Leeds

This paper presents a summary of data from wide range of concretes following periods of marine exposure ranging up to 25 years. Data are presented from more than 100 different concrete mixtures. The various types of concrete include fibre-reinforced concrete (FRC), ultra-high performance concrete (UHPC), concrete with a range of supplementary cementing materials (SCM such as fly ash, slag, and silica fume) and replacement levels (e.g. up to 58% fly ash and 80% slag), lightweight-aggregate concrete (LWAC) and concrete containing alkali-silica reactive aggregate. Testing included measuring chloride concentration profiles, electrochemical corrosion measurements (for steel-reinforced concrete), and various electrical and mechanical properties, in addition to the examination of the microstructure. The data invariably show the importance of the binder type in terms of resistance to chloride ingress and the protection conferred on embedded steel reinforcement, however, the overall performance of SCM concrete was equivocal as high replacement levels were observed to lead to increased surface deterioration (scaling) in some cases. The performance of UHPC was exemplary with little significant chloride penetration and no evidence of surface deterioration after up to 20 years exposure and an estimated 2,000+ freeze-thaw cycles. Expansion (and cracking) due to alkali-silica reaction was observed to be reduced by seawater exposure but, perhaps more significantly, render air-entrained concrete highly susceptible to freeze-thaw damage when the expansion exceeded a certain threshold value. The data are discussed in terms of code requirements and the need for appropriate performance testing. The importance of long-term monitoring of concrete on exposure sites is also discussed.

https://docs.lib.purdue.edu/icdcs/2018/plenary/1