Influence of bauxite residue (red mud) on corrosion of rebar in concrete
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TECHNICAL PAPER
Influence of bauxite residue (red mud) on corrosion of rebar in concrete U. Raghu Babu1 · B. Kondraivendhan1 Received: 13 June 2020 / Accepted: 17 August 2020 © Springer Nature Switzerland AG 2020
Abstract This paper examines the corrosion of rebar embedded in concrete when cement is partially replaced with toxic bauxite residues, known as red mud (RM). The concrete mixtures were made with 100% ordinary Portland cement (OPC), and OPC replaced with 5% of RM (95% OPC + 5% RM). In order to evaluate the rebar corrosion in aforesaid concrete mixes, 5% calcium chloride was admixed while preparing the concrete. The corrosion performance of rebar in OPC concrete and concrete blended with RM was monitored by corrosion potential and linear polarization resistance. In addition, the performance of concrete blended with RM is evaluated through IR (Ohmic drop) compensated electrical resistivity. After 420 days of corrosion monitoring, concrete samples were broken, and visual observations were made on the rebar. X-ray powder diffraction analysis is also carried out on concrete powder samples collected from the steel–concrete interface. The experimental results have shown that the RM blended concrete performed better to resist the corrosion of rebar as compared to OPC concrete across the testing period of 420 days in the case of concrete made of w/cm 0.48. However, the overall corrosion current density increased in RM blended concrete as compared to normal concrete for the w/cm 0.51. Keywords Concrete · Calcium chloride · Corrosion · Rebar · Red mud · Electrical resistivity · LPR
Introduction Alumina from bauxite ore is the raw material for aluminum production [1]. According to the International Aluminum Institute (IAI), production of aluminum across the world has reached 60.4 million tonnes in 2020, which will increase in the coming years [2]. Each ton of alumina production generates approximately 1 to 1.5 tonnes of bauxite residue, generally known as red mud (RM). Continuous and robust growth of alumina production alarms environmental, safety issues, and the disposal problems of hazardous RM as well. RM is disposed of by various methods like pumping, sea dumping, and landfill into storage dams [3]. Failure or leakage of storage dams due to heavy rains can lead to social and environmental contamination when hazardous and toxic bauxite residue is dumped into the ponds or storage dams. * U. Raghu Babu [email protected] B. Kondraivendhan [email protected] 1
Civil Engineering Department, Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat 395007, India
The accident due to the failure of red mud reservoir of the Timfoldgyar alumina plant (Ajka, Hungary) witnessed the importance to safeguard red mud storage dams. Because RM is considered a highly toxic residue, leakage becomes a severe problem for communities living around the alumina refinery. Storage and environmental issues related to RM and its large-scale production attract researchers to explore the sustainable possibilities of u
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