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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Al-Neshawy, Fahim
Aalto University
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (19/19 displayed)
- 2023The Effect of Heat Curing on the Early-Strength Development of Low-Carbon Concrete
- 2023Comprehensive state-of-the-art report for long-term behaviour of concrete structures in repository environment
- 2023Comprehensive state-of-the-art report for long-term behaviour of concrete structures in repository environment
- 2023Combined NDT methods to determine the variations in compressive strength throughout concrete structures
- 2023Reduction of CO2 Emission by Using Low Carbon Concretes with Accelerating Admixtures
- 2023Assessment procedure of determining compressive strength of hardened reinforced concrete structures
- 2023Determining the Location of Steel Reinforcement in Thick Concrete Walls by Non-Destructive Inspection
- 2021Factors for compactibility and risk of segregation for concrete
- 2021Investigation on the effect of entrained air on pore structure in hardened concrete using MIPcitations
- 2021Factors for compactibility and risk of segregation for concrete - Report for contract research project "Compact Air" ; Betonin tiivistettävyyteen ja erottumisherkkyyteen vaikuttavat tekijät – Raportti tilaustutkimusprojektista "Compact Air"
- 2019Design, construction, and NDT of a mock-up for reinforced concrete walls in NPP
- 2019Betonin koostumuksen vaikutus sen tiivistettävyyteen
- 2018Mock-up wall for NDT&E of NPP thick-walled reinforced concrete structures
- 2018Mock-up wall for non-destructive testing and evaluation of thick reinforced concrete structures in nuclear power plants
- 2017“NDT MATRIX” - A Tool for Selecting Non-Destructive Testing Methods for NPP Concrete Structures
- 2016Chemical changes of cement pastes due to the effect of combined carbonation and chloride penetration
- 2016Selection Matrix for Non-Destructive Testing of NPP Concrete Structures
- 2013Condition assessments and corrosion measurements of cooling water chambers in a nuclear power plant
- 2013Condition assessments and corrosion measurements of cooling water chambers in a nuclear power plant
Places of action
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article
Chemical changes of cement pastes due to the effect of combined carbonation and chloride penetration
Abstract
Carbonation of concrete is often the cause of corrosion of steel reinforcement, which is actually one of the main causes for the degradation of concrete structures. The degradation might be more significant in the case of chloride penetration. Carbon dioxide (CO2) in the air can penetrate into the concrete; dissolve in the pore solution, and react with calcium hydroxide, leading to water formation and calcium carbonate precipitation. Carbonation is a diffusion based<br/>phenomenon, where the carbonation front moves inwards at a rate proportional to square root of time. The rate of reaction of hardened cement pastes with CO2 is known to depend strongly on the water cement ratio (w/c) of concrete, mixture composition, pore structure, temperature and curing conditions of concrete and its internal humidity.<br/>When concrete is in contact with a chloride solution, chloride ions diffuse in the pore solution. They appear in concrete both as free Cl-ions (meaning water-soluble ions) in the pore interstitial solution and as chemically bound component of hydrate phases (e.g., Friedel’s salt Ca2Al(OH)6Cl•2H2O]), as well as physically adsorbed on CSH. Free chloride ions are the most dangerous due to their capacity to diffuse towards the steel bars <br/>The objective of this paper is to determine the relationship between the chemical changes of hardened cement pastes and accelerated carbonation using different CO2 concentrations with the presence of chloride ions. The chemical changes of the cement pastes were analyzed using XRay diffractometry and thermal analysis.<br/>According to the results of the XRD-analysis all the sample pastes were partly amorphous and, thus, contained only limited amounts of crystalline compounds. The thermal decomposition of the paste samples exposed with sodium chloride NaCl was somewhat different from the behaviour of the other paste samples.