The influence of cement type and admixture on life span of reinforced concrete utility poles subjected to the high salinity environment of Northeastern Brazil, studied by corrosion potential testing

Abstract

Reinforced concrete structures installed in coastal zones have constantly been threatened by environmental damaging elements. The chloride ion is known as one of the most aggressive of these elements, causing, among other damages, corrosion of the steel reinforcement and then degradation of the concrete matrix. The goal of this work was to determine the influence of cement type on the resistance and durability of reinforced concrete samples with 25 mm cover thickness, when submitted to aging in a 3.4% sodium chloride aqueous solution and in a high salinity marine environment. Reinforced concrete light poles were cast following the same batching procedures, and after the curing period, they were exposed to atmosphere in a corrosion station near Aracaju, Sergipe State, Northeastern Brazil's coast. Two concrete mixtures were made using CPII-F 32 (filler-modified Portland cement): a mix with no admixture and a mix with addition of 8% silica fume swapping fine aggregates. Another mixture was batched with CPV-ARI RS (high-early-strength Portland cement, with sulfur resistance). All the three mixtures were designed with cement content of about 350 kg/m 3 . The performance of the structures was evaluated from the results of physicochemical, mechanical and electrochemical testing, after over a year of natural aging. Corrosion potentials of the reinforced concrete samples and of the cast utility poles were measured in terms of the aging time at the natural environment and under chloride ion accelerated aging at laboratory. The half-cell potential measurements showed that the best results were obtained from the mixture containing CPII-F 32 cement and silica fume, followed by the concrete made with CPV-ARI RS cement. The mixture batched with CPII-F 32 cement without admixture presented the worst durability performance. Keywords: chloride ion, corrosion of steel reinforcement, degradation of concrete, reinforced concrete light pole, electrochemical impedance spectroscopy. Resumo Estruturas de concreto armado instaladas em zonas costeiras têm sido constantemente ameaçadas por elementos ambientais nocivos. O íon cloreto é conhecido como um dos mais agressivos destes elementos, causando, entre outros danos, corrosão da armadura de aço e posterior degradação da matriz de concreto. O objetivo deste trabalho foi determinar a influência do tipo de cimento na resistência e durabilidade de corpos-de-prova de concreto armado com

Revisão sobre ensaios acelerados para indução da corrosão desencadeada por cloretos em concreto armado

“…Assim, o pH da matriz cimentícia na região sofre alteração. Hausmann (1967) ;MILLER, 2003;JOUKOSKI et al, 2004;OTIENO;ALEXANDER;BEUSHAUSEN, 2008;MILLER, 2003;JOUKOSKI et al, 2004), com certa prevalência de 5%, fato esse explicado pela redução do tempo de ensaio.…”

“…Além da simulação da fase líquida presente nos poros de matrizes cimentíceas, os pesquisadores têm empregado como principais métodos para indução da corrosão a adição de cloretos à água de amassamento do concreto ou argamassa (ARYA;XU, 1994;PAGE et al, 2002;GARCIA-ALONSO et al, 2007), a aplicação de campo elétrico para acelerar a penetração de cloretos no concreto a partir de um reservatório contendo solução salina (CASTELLOTE;ALONSO, 2002;PILLAI, 2003), a submissão de concretos a ciclos de secagem e umedecimento HASSANEIN;PAGE et al, 2002;VIEIRA, 2003;SILVA, 2006) e a exposição de concretos à difusão pura por imersão ou através do ensaio de salt ponding test (JOUKOSKI et al, 2004;CHIANG;YANG, 2007).…”

The use of Waste Materials in Utility Poles, Crossarms, Paver, and Reef Balls Concrete Structures: Advantages and Care

“…Nondestructive method, such as electrical half-cell potential with copper-copper sulfate reference electrode, CSE, was used to verify the service life performance of reinforcing steel in concrete in a 3.4% w/w chloride solution and of concrete utility poles submitted to natural aging condition, according to the literature [18][19][20]. e metallic rebar of the poles was connected as the working electrode.…”

“…A marine ECS was built at Caueira beach, in Itaporanga D' Ajuda district, near Aracaju, SE, in northeastern Brazil. It was located at about 2 m above the high tide line of the Atlantic Ocean [19]. Utility poles, crossarms, and concrete material core samples casted with Sf 1 were submitted to natural aging for approximately 500 days.…”

“…Compressive strength tests in 10% w/w Tw resulted in 20 �Pa, presenting at the same time economic bene�ts and environmental advantages for materials repair in hydraulic structures [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”