Chloride-initiated corrosion in alkali activated reinforced concrete

Mangat, P. S.; Ojedokun, Olalekan O.; Lambert, Paul

doi:10.1016/j.cemconcomp.2020.103823

Cited by 38 publications

(11 citation statements)

References 38 publications

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“…Moreover, one of the more likely formed phases is actually an amorphous gel with a highly variable stoichiometry, mainly depending on mix design, thus on the initial materials. An upward trend of shrinkage is generally observed with the increase of the amount of activators in the formulation [39]. RB and CB have been thereby shown earlier to be active additives, i.e., activators.…”

Section: ) Physical Properties and Compressive Strengthmentioning

confidence: 89%

Physicomechanical Properties of Mortars Based On Ordinary Portland Cement with Bauxite as Mineral Additives

Balde

Djangang²,

Balde³

et al. 2022

EJCHEM

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Guinea has one of the world's main reserves of bauxite that can be used as an industrial mineral to produce low-cost building materials and other parts to address the housing and industrial development difficulties in this country. In this line, mortars were manufactured by replacing 5–25 wt.% of Portland cement with raw and 600 °C calcined. Workability and setting time of fresh mortars were measured. Hard products were characterized by linear shrinkage, porosity, and structural and microstructural investigations. The two mineral additives are chemically active since they favored the reduction of the workability and setting time of mortars. In the case of calcined bauxite, ettringite and monosulfoaluminate coexisted regardless of the rate of substitution due to the higher reactivity of alumina, whereas, for raw bauxite, ettringite is only found at 5 and 10 wt.%. Heterogeneous microstructures and increased porosity were revealed with the rate of cement replacement for raw bauxite, whereas for calcined bauxite, the porosity decreased. Even the minimum compressive strengths of both series of mortars, 13 MPa for raw bauxite and 17 MPa for calcined one, enabled their application as construction materials. Favouring the porosity increase, raw bauxite is more appropriate for applications using porous materials.

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Section: ) Physical Properties and Compressive Strengthmentioning

confidence: 89%

Physicomechanical Properties of Mortars Based On Ordinary Portland Cement with Bauxite as Mineral Additives

Balde

Djangang²,

Balde³

et al. 2022

EJCHEM

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“…In PC concrete, alkalinity is buffered by portlandite (Ca(OH) 2 ) and increased further by the concentration of additional alkalis (e.g., Na + and K + ). However, for AAC, the alkalinity of the pore solution depends on the alkali dosage and silicate modulus used in the activating solution, and there can be variations between high and low calcium AAMs (Mangat et al 2021). To calculate the alkalinity of the pore solution in AACs, the composition of the activating solution, mineralogical composition of the precursors, and free water content, were used as inputs in GEM-Selektor.…”

Section: Chloride Thresholdmentioning

confidence: 99%

“…The high pH in AAMs creates a hydroxide concentration gradient between the inner material and the external environment, resulting in leaching of hydroxide (and alkali) ions. Research conducted by Mangat et al (2021) demonstrated that in a high calcium AAM concrete, the hydroxyl ion concentration reduced from 0.155 to 0.017 mol/L between 180 and 1750 days at a cover depth of 10 mm. In comparison, the OHconcentration in PC concrete ranged from 0.014 to 0.009 mol/L under an accelerated corrosive environment with multiple wetting and drying cycles within the same time frame of 1750 days.…”

Section: Chloride Thresholdmentioning

confidence: 99%

Probabilistic Service Life Prediction of Alkali Activated Concretes Exposed to Chloride Induced Corrosion

Chidiac,

Ukrainczyk,

Prentice

et al. 2023

ACT

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In this study, the well-established service life design code defined in fib Bulletin 34 is adapted to predict the time to initiation of reinforcement corrosion in alkali-activated concretes submerged in marine conditions. The model approach is based on the probabilistic calculation of the time needed for a critical concentration of chloride ions, migrating from the external environment towards the rebar, to accumulate at the surface of the steel reinforcement and initiate the corrosion reaction. The information required to define the parameters of the model is derived from literature data, relating the concrete mix designs with accelerated laboratory test results. The findings indicate that alkali-activated concretes with high calcium content can exhibit promising characteristics as a construction material applied for structural application in chloride-rich corrosive environments. The probabilistic approach adopted in this model provides the opportunity to assess the influence of variability in mineralogical composition and reactivity of the precursors with the alkaline activating solution, that influence the chemical evolution and microstructure of the binder matrix. The predicted service life is quite sensitive to these factors, with very high service lives predicted for some alkali-activated concretes but rather short service lives predicted for others, and this must be incorporated into any engineering assessment of future material performance.

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“…This interface is related to the double action of sulphide content in AAMs that consumes oxygen at the steel-mortar interface and reacted with sulphide products on the steel interface [88], which inhibits the formation of the passive layer. Mangat et al [89] investigated the durability of AAS concrete and OPC concrete under the aggressive environment for up to 1750 days; they found the SO 2− 3 content at the steel-AAS concrete interface is up to 80% higher than OPC concrete. However, the corrosion resistance mechanism of this sulphide film on the steel surface remains unclear.…”

Section: Steel-aam Concrete Interfacementioning

confidence: 99%

Research Progress in Corrosion Mechanism of Reinforced Alkali-Activated Concrete Structures

Zhang

Yang

2021

CMD

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In this paper, the recent research progress on the corrosion of reinforced alkali-activated materials (AAMs) concrete structures is reviewed. The corrosion mechanisms induced by carbonation and chloride ingress in AAMs concrete are discussed, from the perspectives of composition, microstructure and pore solution chemistry, in comparison to ordinary Portland cement (OPC) concrete. The steel–alkali-activated concrete interface is a key to investigating corrosion initiation and propagation, which has different physical and chemical characteristics of the steel–concrete interface in OPC concrete. Moreover, the electrochemical process testing methods including half-cell potential and linear polarization resistance are critically discussed with a focus on what could be inherited from the OPC concrete and what criteria are no longer suitable for AAMs concrete due to underestimation in most cases. New data and theories are urgently needed for using AAMs in concrete structures to replace OPC. At the end of this paper, the research gaps and future research needs are summarised for the sake of widespread application of AAMs in concrete structures for sustainable and low-carbon construction.

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Chloride-initiated corrosion in alkali activated reinforced concrete

Cited by 38 publications

References 38 publications

Physicomechanical Properties of Mortars Based On Ordinary Portland Cement with Bauxite as Mineral Additives

Physicomechanical Properties of Mortars Based On Ordinary Portland Cement with Bauxite as Mineral Additives

Probabilistic Service Life Prediction of Alkali Activated Concretes Exposed to Chloride Induced Corrosion

Research Progress in Corrosion Mechanism of Reinforced Alkali-Activated Concrete Structures

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