Chloride-induced corrosion of steel embedded in mortars containing fly ash and spent cracking catalyst

doi:10.1016/j.corsci.2008.02.001

Corrosion Science

Volume 50, Issue 6, June 2008, Pages 1567-1575

https://doi.org/10.1016/j.corsci.2008.02.001 Get rights and content

Abstract

Stationary and non-stationary chloride diffusion coefficients of mortars prepared with ordinary Portland cement partially substituted by spent cracking catalyst (FC3R) and fly ash (FA) have been determined. An accelerated test of chloride migration through the mortar has been performed in order to determine these coefficients. The results show that the presence of FC3R improves chloride binding properties of mortars and the addition of FA reduces the total porosity, both factors leading to a higher resistance to chloride ingress. Corrosion rate of steels embedded in these ternary-binder mortars do not show significant differences compared to reference mortars (with plain cement), so a combined cement substitution as high as 45% by FC3R and FA do not lead to a higher risk of chloride-induced corrosion of steel when tested at an early age.

Introduction

Corrosion of reinforcing steel is of great concern because it is probably the most widespread cause of degradation in reinforced concrete. Initially, reinforcing steel embedded in concrete is naturally protected from corrosion by the high alkalinity of its pore solution [1]. However, this passive state can be broken by the destruction of the passive film that protects steel reinforcement. The main agents leading to destruction of the passive film are penetration of chlorides and carbon dioxide.

Zeolitic catalysts are widely used in petrochemical refining (400,000 tons/year). When the catalytic properties of this product are degraded, the deactivated catalyst must be replaced. Its chemical composition, based on silicoaluminates, together with its zeolitic structure, can be used in concrete, due to its high pozzolanic activity. However, it also increases slightly water demand of mixtures, which can lead to a loss of workability [2], [3], [4], [5], [6], [7], [8], [9], [10].

FC3R is the residue of this zeolitic catalytic cracking catalyst, so it is the product once it has lost its catalytic activity. Additionally, FC3R has a high amount of Al₂O₃, which can bind chlorides coming from external sources thereby reducing the potential for corrosion of reinforcements.

Fly ashes have been used in concretes, because of their pozzolanic activity and because they significantly improve workability by their round-shaped particles [11], [12], [13], [14], [15], [16], [17].

For these reasons, a combination of both pozzolans, can contribute to increase cement substitution in concrete, without a loss in workability, and improve mechanical properties and chloride ingress resistance.

The aim of this work is to evaluate the behaviour of portland cement-FC3R-fly ash mortars in a chloride-contaminated environment. Chloride migration tests were used to determine the chloride ingress resistance of mortars, and the corrosion rates of reinforcing steels embedded in these mortars were monitored when exposed to external chlorides and carbonation.

Section snippets

Materials and sample preparation

All mixtures were prepared using portland cement type CEM I 52.5 R, siliceous aggregate, FC3R (supplied by BP España), fly ashes and tap water. Table 1 compares chemical compositions of cement, fly ash and FC3R. In some mixtures Sika Viscocrete plasticizer was used. Mortars were prepared with a water/cementitious material ratio (w/cm) of 0.4 for specimens used in the migration tests and 0.5 in the corrosion tests. The sand/cementitious material ratio was 3. The migration test specimens were

Migration tests of portland cement-FC3R-fly ash mortars

Fig. 4 shows resistivity measurements of mortars at 28 days of curing time, before they were used in the migration tests. All mortars with pozzolanic substitution showed high resistivity values compared with the plain cement mortars (“Control” and “Plast”) because the pozzolanic reaction produces a denser pore structure due to the formation of additional hydration products in the pores of the mortar. These results suggest that pozzolanic mortars (“FC3R-Plast”, “FA”, “FC3R-FA” and

Conclusions

This research has shown that portland cement-FC3R-fly ash mortars do not add any additional risk under an external chloride attack. These mortars have higher chloride ingress resistance as it has been pointed out by the lower chloride diffusion coefficients obtained for mortars with FC3R and FA. Once corrosion is initiated, the corrosion rate level of steel is similar to that in a control mortar. When combined chloride/carbonation attack is foreseeable the use of these ternary mixed could be

Acknowledgements

This research was supported by Ministerio de Ciencia y Tecnología, Spain (Project MAT 2001-2694). E. Zornoza thanks to Ministerio de Ciencia y Tecnologia for his Doctorate Grant (FPU Programme, Ref. AP2002-3421).

References (31)

H.-L. Chen et al.
Spent FCC catalyst as a pozzolanic material for high-performance mortars
Cement Concrete Comp.
(2004)
K.-C. Hsu et al.
Oil cracking waste catalyst as an active pozzolanic material for superplasticized mortars
Cement Concrete Res.
(2001)
B. Pacewska et al.
Modification of the properties of concrete by a new pozzolan: a waste catalyst from the catalytic process in a fluidized bed
Cement Concrete Res.
(2002)
B. Pacewska et al.
Effect of waste aluminosilicate material on cement hydration and properties of cement mortars
Cement Concrete Res.
(2002)
J. Payá et al.
Fluid catalytic cracking catalyst residue (FC3R): an excellent mineral by-product for improving early-strength development of cement mixtures
Cement Concrete Res.
(1999)
J. Payá et al.
Evaluation of the pozzolanic activity of fluid catalytic cracking residue (FCC): thermogravimetric analysis studies on FCC-portland cement pastes
Cement Concrete Res.
(2003)
J.-H. Wu et al.
The effect of waste oil-cracking catalyst on the compressive strength of cement pastes and mortars
Cement Concrete Res.
(2003)
L. Jiang et al.
A model for predicting carbonation of high-volume fly ash concrete
Cement Concrete Res.
(2000)
J. Payá et al.
Mechanical treatment of fly ashes. Part I: physico-chemical characterization of ground fly ashes
Cement Concrete Res.
(1995)
J. Payá et al.
Mechanical treatment of fly ashes. Part II: particle morphologies in ground fly ashes (GFA) and workability of GFA-cement mortars
Cement Concrete Res.
(1996)

J. Payá et al.

Comparisons among magnetic and non-magnetic fly ash fractions: strength development of cement-fly ash mortars

Waste Manage.

(1996)

J. Payá et al.

Mechanical treatment of fly ashes. Part III: studies on strength development of ground fly ashes (GFA)-cement mortars

Cement Concrete Res.

(1997)

J. Payá et al.

Mechanical treatment of fly ashes. Part IV: strength development of ground fly ash cement mortars cured at different temperatures

Cement Concrete Res.

(2000)

C. Andrade

Calculation of chloride diffusion coefficients in concrete from ionic migration measurements

Cement Concrete Res.

(1993)

M. Castellote et al.

Measurement of the steady and non-steady chloride diffusion coefficients in a migration test by means of monitoring the conductivity in the anolyte chamber. Comparison with natural diffusion tests

Cement Concrete Res.

(2001)

Cited by (51)

Steel corrosion rates in concrete in contact to sea water
2023, Cement and Concrete Research
There are few data on corrosion rates of reinforcements in real marine conditions. In present work corrosion rates at long term are presented in the case of small specimens and large reinforced concrete blocks in direct contact to natural sea water. The small specimens had embedded bars at different cover depths and the tests lasted from 10 to 23 years and the corrosion rates have been measured periodically by using the polarization resistance method. The large blocks have been semi-buried around 25 years in the tidal area of a beach in the South of Spain. Their corrosion rates have been measured only four times and the curiosity is that the bars are not corroding in spite of the high contamination at the 3 cm cover depth after so long exposure. Finally, is presented the statistical distribution of corrosion rates found in other structures also in marine environment.
Investigation on mechanical and micro properties of concrete incorporating seawater and sea sand in carbonized environment
2021, Construction and Building Materials
This study aims to explore the mechanical and micro performance of seawater and sea sand concrete under accelerated carbonization environment. This study designed a total of 8 mix ratios, mainly to explore the effects of different water-cement ratios and different mineral admixtures (FA and LC2) on the properties of seawater and sea sand concrete after carbonization. To better evaluate and understand the mechanical properties, the micro morphology analysis was carried out by SEM, the hydration product analysis was carried out by TGA and XRD, and the pore structure was studied by MIP. The results show that the standard curing of seawater and sea sand concrete for 28 days can increase the compressive strength by about 10% compared with ordinary concrete, but the final mechanical strength is similar to ordinary concrete under the condition of long-term accelerated carbonization. The carbonation resistance performance of seawater and sea sand concrete is approximately twice that of ordinary concrete, but when FA and LC2 are added, the property of carbonation resistance will be reduced by more than two times. The large amount of chloride ions added into the concrete by seawater and sea sand will reduce the total porosity of the concrete by about 13% and improve the pore size distribution. In general, to improve the current shortage of natural resources such as river water and river sand, it is feasible to consider adding seawater and sea sand into ordinary concrete.
Methods of accelerating chloride-induced corrosion in steel-reinforced concrete: A comparative review
2021, Construction and Building Materials
Rebar corrosion has been recognized as a major durability issue of the reinforced concrete (RC) structures over recent decades, prompting the necessity to study the corrosion behavior of steel in concrete during the service life. To estimate service life of RC structure, the corrosion of reinforcing steel is generally accelerated by means of the impressed current technique in limited available time. In the literature, several accelerated laboratory corrosion methods have been proposed, however the results varied greatly as chloride concentrations and testing conditions were different. Researchers are unsure which testing methods can be used to give reliable results to simulate the real-life corroded RC structure. This review paper aims to systematically compare and evaluate different methods of accelerating chloride-induced corrosion of steel reinforcement in concrete. First, the accelerated methods categorized into three groups namely, the impressed current (IC), the chloride ion diffusion (CID) and the artificial climate environment (ACE) are briefly discussed. Then, the key influencing factors (i.e. current density, salt concentration, service load) affecting the corrosion results in different methods are compared and evaluated. Finally, the corrosion products and acceleration method are comprehensively discussed. By this comparative review, it is believed that researchers can have a better understanding of different accelerated corrosion methods along with the influencing factors. So they could select or even develop the most suitable techniques to yield reliable corrosion test results.
One-part alkali-activated concrete with seawater
2021, Handbook of advances in Alkali-activated Concrete
The development of one-part alkali-activated materials (AAMs) is of great potential, since conventional AAMs’ production involves the utilization of corrosive, viscous, and concentrated aqueous alkali solution. In addition, huge amount of water is consumed for the production of cementitious construction materials, while many places in the world are suffering from not having enough fresh water. Consequently, developing one-part AAMs that can be directly mixed using seawater is of great economical and sustainable significance. This chapter discusses recent investigations on one-part AAMs with seawater in terms of binder composition, reaction products, physical properties and durability, as well as current research limits and potential opportunities.
Study of seawater mixed one-part alkali activated GGBFS-fly ash
2020, Cement and Concrete Composites
Citation Excerpt :
Studies have reported that C–S–H can adsorb chloride by exchanging hydroxyl ions from the C–S–H layers with chloride ions from pore solution [27,41]. In Ref. [42], increased chloride binding capacity was detected in fly ash-blended cement mortar, which was assigned to the formation of hydrated calcium aluminates (C-A-H) and C-A-S-H phases. Yogarajah and Nawa [43] stated that the chloride binding effect in slag-blended cement is dominated by the C-A-S-H and Friedel's salt.
This work tests the suitability of seawater for the synthesis of one-part alkali-activated material. The setting time, strength development, reaction product and steel corrosion of seawater mixed one-part alkali-activated ground granulated blast furnace slag-fly ash are investigated. Compared with freshwater, seawater can accelerate the alkali activation process, reflecting as shortened setting times. The obtained material possesses high early and long-term strength; the 3 d and one-year compressive strength are over 25 MPa and 73 MPa, respectively. In addition, the seawater mixed material has very slight negative influence on the reinforcement steel. Apart from the alkali activation process, chloride-binding property by synthesized material was also studied. Formation of chloride-bearing reaction product was detected, which might contribute to retard chloride and minimise the corrosion risk. All these results contribute to better understand the chemistry of alkali-activated materials and promote its application.
Corrosion performance of carbon steel in N-doped mesoporous carbon spheres (NMCS)-containing alkaline medium in presence of chloride
2019, Materials Today Communications
The electrochemical response of carbon steel in chloride-free or chloride-containing 0.1 M and 0.9 M NaOH, in the presence of 0.016 wt.% NMCS, is the subject of this work. The NMCS exhibited a negative (in 0.1 M NaOH) and positive (in 0.9 M NaOH) zeta-potential. This determined altered steel electrochemical response, improved overall, especially in chloride-containing 0.9 M NaOH. The effect was related to an enhanced Fe³⁺ contribution in the passive film, when NMCS were present. The improved corrosion resistance was also attributable to a NMCS-triggered competition of OH⁻ vs. Cl⁻ ions in the medium, in other words, NMCS interference to promote passive layer stability.

View all citing articles on Scopus

View full text

Chloride-induced corrosion of steel embedded in mortars containing fly ash and spent cracking catalyst

Abstract

Introduction

Section snippets

Materials and sample preparation

Migration tests of portland cement-FC3R-fly ash mortars

Conclusions

Acknowledgements

Cement Concrete Comp.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Waste Manage.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.

Cement Concrete Res.