A model for predicting time-dependent chloride binding capacity of cement-fly ash cementitious system

Sumranwanich, Taweechai; Tangtermsirikul, Somnuk

doi:10.1007/bf02479635

Cited by 36 publications

(7 citation statements)

References 15 publications

(22 reference statements)

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“…In this experimental investigation, the authors 89 studied the durability-related performance of concrete containing fine RMA from crushed bricks. Since clay bricks normally contain high contents of alumina (Al 2 O 3 ) 91 , which are comparable to those of metakaolin and fly ash 92 , it is possible that by grinding them to a fine enough state they may cause a pozzolanic reaction with the cement, producing tricalcium aluminate (3CaO.Al 2 O 3 or C 3 A) which is known to be partly responsible for the chemical binding of chloride ions to form Friedel's salt (Ca 6 Al 2 O 6 .CaCl 2 .10H 2 O). Figure 1c presents the relative effect of adding increasing amounts of coarse RA to the total charge passed.…”

Section: Recycled Aggregate Replacement Levelmentioning

confidence: 99%

Prediction of Chloride Ion Penetration of Recycled Aggregate Concrete

2015

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This paper provides a literature review and analysis of the various influencing aspects related to the use of recycled aggregates, sourced from construction and demolition waste, on the chloride ion penetration of concrete. A statistical analysis on the effect of incorporating increasing amounts of recycled aggregates of different type, size, and class on the chloride ion migration and total charge passed of concrete is also presented. The paper also presents the relationship between these properties and the corresponding compressive strength. The results show strong correlations between these parameters, which are independent of other aspects related to recycled aggregate use and made it possible obtaining a relationship between the values acquired via NT Build 492 and ASTM C1202.

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Section: Recycled Aggregate Replacement Levelmentioning

confidence: 99%

Prediction of Chloride Ion Penetration of Recycled Aggregate Concrete

2015

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“…The chloride-binding affinity of cementitious materials and its dependence on various concrete mix-proportioning parameters have been reported by many investigators [15][16][17]. In terms of reaction mechanism, the main form of chloride binding is generally reported as a chemical reaction with the aluminate and iron phases to produce calcium chloro-aluminate of the Friedel's salt type.…”

Section: Chloride Bindingmentioning

confidence: 97%

“…The C 4 AF binds just as much chloride ions as the C 3 A phase. This follows from the ability of the C 4 AF phase to chemically bind chloride ions in a similar way to C 3 A, resulting in the formation of chloro-complex with an identical crystalline structure that is ferrite analog to the Friedel's salt [16]. In accordance with the anion exchange hypothesis, the formation of the Friedel salt (F r ) in which unreacted aluminates react with intruding free chloride ions (Cl − ) in the presence of portlandite (calcium hydroxide, CH) can be represented as follows:…”

Section: Chloride Bindingmentioning

confidence: 98%

Transport Modeling of Chlorides with Binding in Concrete

et al. 2012

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Chloride-induced corrosion is one of the most revealing cause of deterioration leading to premature durability loss by structural concrete. Among mechanisms governing penetration of chloride ions into the concrete, ingress by simple diffusion is the most decisive one for concentration-driven transport. The use of Fick's law of diffusion of the second type does in general permit a modest preliminary analysis of the diffusive transport subject to certain constraints, primarily associated with stationary chloride diffusion coefficient hypothesis. A realistic critique to such analysis based on constant chloride diffusivity is however its total disregard of intrinsic chloride-binding capacity evidently exhibited by cement-based materials constituent to the concrete. Given that the chlorides are also partly free and partly bound in concrete, the significance of chloride binding for a more accurate service life analysis of the concrete is of practical concern. Moreover, the challenge raised by chloride binding against the invariant diffusivity assumption cannot also be ignored, because only free chlorides diffuse into and through the bulk concrete to thereafter directly pose corrosion risk. Since chloride transport in cementitious material such as concrete based on one or another chloride-binding mechanism may also be quite different, careful choice of chloride-binding model, consistent with the underlying phenomenological behavior, is critical for its implication to service life predictions. The aim of this study is therefore to examine the effect of chloride binding in terms of their isotherm formulations on time to corrosion activation resulting from transport of chloride ions in saturated concrete. Numerical analysis employing nonlinear finite element modeling techniques is used to account for null, linear and nonlinear chloride-binding formulations, including Langmuir and Freundlich representations for the nonlinear types, on the chloride transport problem. Results of the analysis, in view of experimental chloride-binding and penetration profile data mined from the literature, are presented to quantifiably underscore the effects that various binding parameters significantly have on onset of chloride-induced corrosion in relation to specific durability requirements.

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“…Conventional PC concrete has higher binding capacity due to the presence of C 3 A and C 4 AF in its binder (Table 2). The unhydrated portion of aluminate (C 3 A) and aluminoferrite (C 4 AF) of PC binders reacts with the chloride ions in the pore solution during the chloride exposure period, forming Friedel's salt (Ca 6 Al 2 O 6 .CaCl 2 .10H 2 O) and calcium chloroferrite [51]. The lack of calcium aluminate (C 3 A)…”

Section: Chloride Contents and Alkalinity Of Pore Solution 331 Free Chloridementioning

confidence: 99%

Chloride-initiated corrosion in alkali activated reinforced concrete

Mangat

Ojedokun

Lambert

2021

Cement and Concrete Composites

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The use of ordinary Portland cement (PC) as the principal binder in concrete brings with it significant environmental challenges through the consumption of fossil fuels and emission of carbon dioxide (CO 2 ) during cement production. Concrete specimens made with an alkali activated cementitious material (AACM) produced from an alternative binder and conventional Portland cement concrete were exposed to corrosion inducing environments for 1 750 days to monitor their relative durability. AACM concrete shows higher corrosion potential E corr and corrosion current densities I corr than PC concrete due to a reducing environment around the steel surface in AACM concrete, caused by high sulfide concentration in the pore solution.Corrosion resistance of the AACM concretes increases with increasing molarity of the alkali activator, at a constant liquid to binder ratio. The threshold Cl -/OHvalue for pitting corrosion initiation in the AACM concrete is between 2.1 and 2.8 compared with 1.08 for the control PC concrete. The AACM concrete evaluated in this study showed greater resistance to chloride induced corrosion than the PC concrete.

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A model for predicting time-dependent chloride binding capacity of cement-fly ash cementitious system

Cited by 36 publications

References 15 publications

Prediction of Chloride Ion Penetration of Recycled Aggregate Concrete

Prediction of Chloride Ion Penetration of Recycled Aggregate Concrete

Transport Modeling of Chlorides with Binding in Concrete

Chloride-initiated corrosion in alkali activated reinforced concrete

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