The effect of salt additions on the alkalinity of Ca(OH)2 solutions

Newton, C.J.; Sykes, J. M.

doi:10.1016/0008-8846(87)90039-1

Cited by 18 publications

(9 citation statements)

References 8 publications

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“…The chloride threshold value required to initiate rebar corrosion depends somewhat on the pH of the concrete pore solution at the level of the reinforcing steel. Both MgCl 2 and CaCl 2 cause a decrease in pH, whereas NaCl raises the pH, suggesting that the threshold for NaCl may be somewhat higher than for MgCl 2 and CaCl 2 (20). However, if the diffusion rate of the cation is much lower than that of chloride ion, the pH effects will not necessarily influence the corrosion initiation threshold value.…”

Section: Corrosion Effects Of Chloride-based Snow-and Ice-control Chemicalsmentioning

confidence: 99%

“…The replacement of Ca(OH) 2 with Mg(OH) 2 also reduces the pH of the pore solution (from 12.6 to 9.0 for saturated solutions); if this pH reduction occurs at the rebar level, the rebar steel loses passivation and thus allows the onset of active corrosion, even in the absence of chloride ions (20). The rate at which Mg(OH) 2 replaces Ca(OH) 2 is not known; however, such an effect-combined with the presence of chloride ions-further accelerates rebar corrosion.…”

Section: Chemical Impactsmentioning

confidence: 99%

See 1 more Smart Citation

Relative Effects of Sodium Chloride and Magnesium Chloride on Reinforced Concrete: State of the Art

Mussato¹,

Gepraegs²,

Farnden

2004

Transportation Research Record: Journal of the Transportation R

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Magnesium chloride (MgCl2) use for snow and ice control is becoming a well-established practice but has been limited to the past 10 years. Impacts associated with sodium chloride (NaCl) use are well documented, but concerns have been raised regarding the potential effects of MgCl2 use on concrete and steel reinforcement. The British Columbia Ministry of Transportation intended to establish guidelines for MgCl2 use by highway maintenance contractors. Information was gathered from available literature and interviews with academia and industry. Generally, few studies directly and comprehensively address the topic, and although significant research efforts are currently under way, results are not expected for several years. Past laboratory studies suggest that MgCl2 reacts with cement paste to reduce concrete strength and degrade concrete. Studies also suggest that chloride ions associated with MgCl2 have higher diffusion coefficients than those associated with NaCl. Field studies are limited, but laboratory coefficients for chloride ion diffusion correlate with results of a field study conducted in Montana. Higher chloride diffusion coefficients can reduce the initiation time for chloride-induced corrosion of reinforcing steel. No evidence to date directly links the increased deterioration of a structure to MgCl2 use; however, the history of use is short, and caution is recommended until additional studies can establish more evidence.

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Section: Corrosion Effects Of Chloride-based Snow-and Ice-control Chemicalsmentioning

confidence: 99%

Section: Chemical Impactsmentioning

confidence: 99%

Relative Effects of Sodium Chloride and Magnesium Chloride on Reinforced Concrete: State of the Art

Mussato¹,

Gepraegs²,

Farnden

2004

Transportation Research Record: Journal of the Transportation R

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“…[16,21,22,[24][25][26][27] Carsana and Bertolini [15] attributed the corrosion to the development of pore water pH greater than 14. Newton and Sykes [28] described how the elevated sulfate ion concentrations in alkaline solutions with excess calcium hydroxide allow for an increase in pH. However, the presence of pozzolans including silica fume would promote reactions to consume hydroxyl ions, resulting in lowering the pH.…”

Section: Introductionmentioning

confidence: 99%

Identification of steel corrosion in alkaline sulfate solution by electrochemical noise

Permeh

Lau

Duncan

et al. 2021

Materials & Corrosion

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Research on the effects of sulfate ions on steel corrosion has been conducted in response to the observations of premature localized corrosion of steel strands in cementitious grouts in posttensioned bridge construction. Electrochemical noise (EN) was shown to be an effective technique to assess the development of localized corrosion of steel in the alkaline sulfate solution.General statistics of the EN potential and current time signatures revealed the negative effect of elevated sulfate concentrations and the development of pitting events. Spectral analysis indicated an increase in the characteristic charge and decrease in characteristic frequency with sulfate ion concentration, whereas an increase in the overall corrosion rate was observed, indicating the development of pitting corrosion. Pitting events could be sustained in solutions above 10 g Na 2 SO 4 /L H 2 O and more extensive localized corrosion developed above 20 g Na 2 SO 4 /L H 2 O.

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“…P=(1-(W2-W1))/100 (1) P-connectivity rate (%); W2-the weight of the test block take out of water after 24h (g); W1-the weight of the test block in water after 24h (g); V-specimen appearance volume (cm 3 ). The ex-situ leaching method: selected sample crushing, grinding, sieving (0.08mm), take samples with 10g, added the samples to 10 times weight distilled water, in order to prevent the carbide plugged the bottle, shake evenly every 5min, determination the pH value after filtered by filter in 2h.…”

Section: 1mentioning

confidence: 99%

“…And more and more researchers are also attracted by the green concrete, vegetation and biological adaptive concrete. However, the study on the alkaline release characteristics of the porous concrete has not been paid much attention, and the ex-situ leaching method is a preferred method used to evaluate the alkalinity of the porous concrete [3] , Although this method has a more mature application effect. However, the specific surface area and pore characteristics of porous concrete are different from those of conventional concrete,Therefore, there is great differences of alkaline release characteristics between porous concrete and conventional concrete.…”

Section: Introductionmentioning

confidence: 99%

The Research of Alkaline Release Characteristics of Biological Adaptive Porous Concrete

Xiao¹,

Jiang²

2017

Proceedings of the 2017 2nd International Symposium on Advances in Electrical, Electronics and Computer Engineering (ISAEECE 20

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Abstract. In this article, the acid-base properties of porous concrete leaching solution were studied, The pH value of the porous concrete soaking solution was measured by the method of continuous soaking and repeated soaking, at the same time, the pH value of leaching solution and the ex-situ leaching method were compared and analyzed. The results show that the alkaline release are significant differences between porous concrete and conventional concrete. In the unit time, the alkaline release rate of porous concrete is faster than the rate of ordinary concrete. Moreover, the pH value of the leaching solution is significantly decreased after soaking several times, and it is also shown that there is a positive correlation between the rate of alkali release and porosity of porous concrete. At the same time, it is concluded that the ex-situ leaching method is not suitable for the alkaline practical measurement of the porous concrete.

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The effect of salt additions on the alkalinity of Ca(OH)2 solutions

Cited by 18 publications

References 8 publications

Relative Effects of Sodium Chloride and Magnesium Chloride on Reinforced Concrete: State of the Art

Relative Effects of Sodium Chloride and Magnesium Chloride on Reinforced Concrete: State of the Art

Identification of steel corrosion in alkaline sulfate solution by electrochemical noise

The Research of Alkaline Release Characteristics of Biological Adaptive Porous Concrete

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