Experimental study of the effect of chloride exposure on concrete beams reinforced with bars of different steel materials

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Volume Title

Insinööritieteiden korkeakoulu | Master's thesis

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Date

2019-12-16

Department

Major/Subject

Mcode

Degree programme

Master's Programme in Building Technology (CIV)

Language

en

Pages

56+34

Series

Abstract

Chloride attack is predominantly attributed by researchers as being the most damaging mechanism of corrosion to reinforced concrete structures. The deteriorating implications of chloride-induced corrosion may range from an initial moderate decline of aesthetical qualities of a building to far more severe consequences, such as the significant reduction in its serviceability lifespan culminating in the ultimate failure to meet minimum standards of structural integrity. Considering the seriousness of the matter of maintaining a structure that satisfies safety and functionality parameters, this study provides an assessment of the effects of chloride-induced corrosion in terms of the mechanical properties of reinforced concrete structures. This research has investigated the effects of chloride corrosion on the load-bearing capacity of 81 concrete beams reinforced by either one of the eight steel bars utilised in this experimental study. These beams were stored during a period of 16 years under Eu-rocode’s exposure class XD3. The load-bearing capacity of the beams was determined by performing a three-point bending test. In addition, the ultimate strength and elongation after fracture of a number of reinforcement bars were established. Furthermore, a follow-up experiment was conducted to verify that chloride ions were, in fact, present in the chemical composition of the steel-concrete interface. SEM analyses have detected chlorine and sodium atoms in the vicinity of the steel and concrete, leading to the conclusion that chloride ions were the main factor contributing to corrosion initiation. The mechanical experiments revealed that chloride corrosion has incurred a negative impact on the load-bearing capacity of the tested specimens when compared to results obtained 16 years earlier, prior to XD3 exposure. In addition, it was found that the ductility of the reinforcement bars has decreased significantly to the point where they no longer respect minimum values prescribed by Eurocode. This study provided experimental evidence on the damaging effects that chloride-induced corrosion has on the mechanical properties of reinforced concrete structures.

Description

Supervisor

Puttonen, Jari

Thesis advisor

Sistonen, Esko

Keywords

chloride-corrosion, reinforced concrete, load-bearing capacity, steel reinforcement

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Citation

Permanent link to this item

https://urn.fi/URN:NBN:fi:aalto-201912226571

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[dipl] Insinööritieteiden korkeakoulu / ENG