Chloride induced corrosion in different fly ash based geopolymer concretes

Gunasekara, Chamila; Law, David W.; Bhuiyan, Shamir; Setunge, Sujeeva; Ward, Liam

doi:10.1016/j.conbuildmat.2018.12.168

Cited by 122 publications

(52 citation statements)

References 36 publications

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“…Most investigations of the steel reinforcement durability in GP and AAB concretes are focused on corrosion processes caused by the ingress of chlorides [48][49][50][51][52][53][54][55], and only few investigate carbonation [56,57] and almost none look at leaching or geopolymerization processes.…”

Section: Molecules 2019 24 X For Peer Review 3 Of 24mentioning

confidence: 99%

“…This value specifies the type of reinforcement materials required [15,16] and influences the long-term stability of The currently available results are inconsistent with one another. In the case of chloride-induced corrosion, for example, the investigations by Monticelli et al [54], Tittarelli et al [50], and Farhana et al [56] have shown greater protection for steel reinforcement bars in low-calcium fly ash-based GP-mortars/concrete compared to cementitious materials, whereas Babaee and Castel [48] have demonstrated comparable protection, and Gunasekara et al [55] lower protection.…”

Section: Introductionmentioning

confidence: 99%

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Alkalinity and Its Consequences for the Performance of Steel-Reinforced Geopolymer Materials

et al. 2020

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This paper investigates the development of the alkalinity and its impact on carbon steel reinforcement embedded in alkali-activated fly ashes (AAFA) and alkali-activated fly ashes with ten percentage mass (wt%) of blast furnace slag (AAFAS)-based materials (geopolymer–GP). The pH analysis of eluates indicates a remarkable decrease of alkalinity in AAFA and AAFAS in the first hours of the geopolymerization process. Phenolphthalein solution and pore solution tests on concretes also show a sharp decrease of alkalinity with increased Ca content in the binder due to carbonation. Micro X-ray computer tomography (µXCT) and electrochemical techniques indicate that the changed pH in the GP systems was accompanied by a decrease in the corrosion rates of steel reinforcement when compared to ordinary Portland cement (OPC) systems. In contrast to calcite and vaterite, which were detected in OPC and AAFAS after a carbonation process, only sodium carbonate natron was determined at lower levels in AAFA by X-ray diffraction (XRD).

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Section: Molecules 2019 24 X For Peer Review 3 Of 24mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Alkalinity and Its Consequences for the Performance of Steel-Reinforced Geopolymer Materials

et al. 2020

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“…However, the chemical method is required to destroy the structure, and the location, speed, and state of corrosion cannot be determined. As a new testing technology in recent years, the electrochemical method has the advantages of simple equipment, low cost, high accuracy, wide range, and high sensitivity [ 31 ]. Therefore, electrochemical methods were used to evaluate the corrosion of steel bars embedded in concrete.…”

Section: Introductionmentioning

confidence: 99%

Steel Corrosion Evaluation of Basalt Fiber RPC Affected by Crack and Steel-Concrete Interface Damage Using Electrochemical Methods

Liu¹,

Lyu²,

Zhang³

et al. 2020

Sensors

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Basalt fiber (BF) is a new anti-corrosion and environmentally friendly material, which is expected to delay the corrosion process of steel bars and improve the durability of reinforced reactive powder concrete (RPC). The electrochemical method is a nondestructive testing and real-time monitoring technique used to characterize the corrosion behaviors of steel bars embedded in concrete structures. In this paper, the electrochemical technique was employed to evaluate the corrosion of steel bars embedded in basalt fiber modified reactive powder concrete (BFRPC). Besides, crack and steel-concrete interface damage (SCID) were considered as typical factors that affect steel corrosion in concrete. Thus, both reinforced fiber-free RPC and BFRPC specimens with crack and SCID were prepared for evaluating the steel corrosion behaviors by electrochemical methods. The results revealed that both crack and SCID would aggravate the steel corrosion, and the crack was the major factor that affects the corrosion process. Moreover, the excellent compactness of BFRPC and the bridging action of BF could effectively prevent the concrete cracking and steel corrosion process of concrete. Using reinforced BFRPC instead of ordinary concrete in practical projects could greatly extend the service life of steel bars.

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“…These pre-treatments certainly eliminate the chlorides and inorganic salts in MSWI-FA but generate other wastes and increase the quantity of energy required for the synthesis and the total cost of the product. The efficient way to valorize MSWI-FA in construction is its use in the process, which displays limited signs of heavy metals leaching and the formation of the corrosion product in the presence of chlorine such as geopolymerization [8][9][10].Geopolymer cement are considered eco-friendly binder materials and potential alternative to Portland cement (OPC) in specific applications since they produce around 80% less CO 2 than Portland cement [11]. It has the potential to use alumina-silicate materials either from natural occurring waste, synthetic waste, or from industrial waste.…”

mentioning

confidence: 99%

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confidence: 99%

Characterization and Leachability Behaviour of Geopolymer Cement Synthesised from Municipal Solid Waste Incinerator Fly Ash and Volcanic Ash Blends

et al. 2018

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Municipal solid waste incinerator fly ash (MSWI-FA) was used synergistically with volcanic ash (VA) to synthesize Geopolymer cement. The effects of the incorporation of 0%, 30%, and 50% of VA and the alkalinity of activating solution on the structure and properties were studied by using the X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field emission gun scanning electron microscopy (FEG-SEM), and mechanical testing. The encapsulation efficiency of the cements was carried out by using a toxicity characteristic leaching procedure (TCLP). The geopolymerization of MSWI-FA promoted the formation of new minerals such as Thernadite (Na 2 SO 4 ), Hydrocalumite (Ca 4 Al 2 O 6 (CO 3 ) 0.67 (SO 3 ) 0.33 ), C-S-H, and Faujasite-Na(Na 2 Ca) 0.075 (Al 0.3 Si 0.7 )O 2 (H 2 O) 0.22 . The Geopolymer cement synthesized with the addition of 50% of VA at 6M NaOH concentration, which exhibited the most compact microstructure. This was the highest strength with the best encapsulation ability. The microstructure analysis of the MSWI-FA-VA system revealed the coexistence of C-S-H and N-A-S-H phases as the main cementitious binders. The TCLP results of cement vis a vis raw MSWI-FA showed the leaching of metals reduced to a great extent. This was much lower than the permissible limit fixed by the United States Environmental Protection Agency (USEPA) for the toxicity characteristic. Furthermore, an attempt was made to correlate the microstructure with mechanical properties.Recycling 2018, 3, 50 2 of 14 of heavy metals content. Therefore, MSWI-FA is classified as a hazardous waste [3,4]. Owing to its chemistry, fine particle size, and pozzolanic behavior, MSWI-FA has the potential to be used as a mineral additive in cement. However, its high chlorine content restricts its application in construction material. Although the cement paste is not much affected by chloride except for increased solubilization of cement solids, chlorine is detrimental to the passivation of embedded steel [5]. To avoid this problem, some pre-treatment methods such as water washing and thermal treatment have been proposed [3,6,7]. These pre-treatments certainly eliminate the chlorides and inorganic salts in MSWI-FA but generate other wastes and increase the quantity of energy required for the synthesis and the total cost of the product. The efficient way to valorize MSWI-FA in construction is its use in the process, which displays limited signs of heavy metals leaching and the formation of the corrosion product in the presence of chlorine such as geopolymerization [8][9][10].Geopolymer cement are considered eco-friendly binder materials and potential alternative to Portland cement (OPC) in specific applications since they produce around 80% less CO 2 than Portland cement [11]. It has the potential to use alumina-silicate materials either from natural occurring waste, synthetic waste, or from industrial waste. Thus, varieties of alumina-silicate and industrial waste used for Geopolymer cement synthesis involve volcanic ash, glass powder,...

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Chloride induced corrosion in different fly ash based geopolymer concretes

Cited by 122 publications

References 36 publications

Alkalinity and Its Consequences for the Performance of Steel-Reinforced Geopolymer Materials

Alkalinity and Its Consequences for the Performance of Steel-Reinforced Geopolymer Materials

Steel Corrosion Evaluation of Basalt Fiber RPC Affected by Crack and Steel-Concrete Interface Damage Using Electrochemical Methods

Characterization and Leachability Behaviour of Geopolymer Cement Synthesised from Municipal Solid Waste Incinerator Fly Ash and Volcanic Ash Blends

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