Concrete alteration due to 55years of exposure to river water: Chemical and mineralogical characterisation

Rosenqvist, Martin; Bertron, Alexandra; Fridh, Katja; Hassanzadeh, Manouchehr

doi:10.1016/j.cemconres.2016.11.012

Cited by 30 publications

(28 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Extensive filling of air voids by ettringite was found in a surface near zone (approx. 3-8 mm) in a 55 years old Swedish concrete dam (w/c = 0.55) exposed to fresh water [35]. Cracks might act similarly to voids.…”

mentioning

confidence: 97%

Mineralogical Sequence of Self-Healing Products in Cracked Marine Concrete

Danner

Jakobsen

2019

Minerals

View full text Add to dashboard Cite

Self-healing of cracked concrete beams after 25 years of marine exposure was investigated. The extent of self-healing and the chemical and mineralogical composition of the self-healing products were characterized, and mechanisms proposed. There was no effect of varying silica fume (4%, 12%) and fly ash content (0%, 20%) on the mineralogy and chemistry of the self-healing products and the extent of self-healing. Crack widths smaller than 0.2 mm appeared closed. With increasing crack depth, a sequence of changing mineralogy of self-healing products was found. In the outer part of the crack (0–5 mm depth from the exterior surface) only calcite was precipitated followed by brucite layers from 5–30 mm depth. The brucite was occasionally intermixed with calcite. At crack depths >30 mm only ettringite was observed. It is hypothesized that the mineralogical sequence observed with increasing crack depth occurs due to an increasing pH of the solution inside the crack with increased crack depth. Self-healing of cracks in marine exposed concrete is proposed to happen through precipitation of ions from seawater partly in reaction with ions from the cement paste in the outer part of the crack and through dissolution and reprecipitation of ettringite at larger crack depths.

show abstract

mentioning

confidence: 97%

Mineralogical Sequence of Self-Healing Products in Cracked Marine Concrete

Danner

Jakobsen

2019

Minerals

View full text Add to dashboard Cite

show abstract

“…This is illustrated by data from a 55 years old Swedish concrete dam (w/c = 0.55) exposed to fresh water, where extensive filling of air voids by ettringite was found a surface near zone (approx. 3-8 mm) [94].…”

Section: Filling Of Macroscopic Pores With Solidsmentioning

confidence: 99%

The steel–concrete interface

et al. 2017

View full text Add to dashboard Cite

Although the steel-concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made. This report was prepared by the working group within RILEM TC 262-SCI, and further reviewed and approved by all members of the RILEM TC 262-SCI.

show abstract

“…Na sequência, este novo aumento da porosidade resultará em maior coeficiente de difusão ou permeabilidade, que mais futuramente acelerará o processo da lixiviação, num efeito progressivo (Yang et al 2012, Keshu et al 2015. Exposições à lixiviação por longo prazo podem alterar significativamente o concreto da superfície (Rosengvist et al 2017), o que acarreta a redução do efeito protetivo do concreto nas barras de aço (Tang et al 2016), em função da diminuição do pH, induzindo à corrosão das armaduras (Phung et al 2016). A presença de lixiviação de cálcio tem sido relatada desde a década de 1920.…”

Section: Introductionunclassified

“…Apesar disso, há poucos casos em que estruturas de concreto massa foram danificadas por esse processo, uma vez que a taxa de degradação é relativamente lenta (Narakai et al 2006). A fim de garantir uma longa vida útil das estruturas hidráulicas, é necessário um melhor entendimento dos efeitos das águas naturais na deterioração do concreto (Phung et al 2016, Rosengvist et al 2017. Durante o processo construtivo de Itaipu, no final da década de 1970, foi necessária a substituição de material aluvionar na fundação das unidades centrais da casa de força, na região do leito do Rio Paraná, por um concreto massa de diâmetro máximo de agregado 152mm e resistência característica de projeto de 10 Mpa.…”

Section: Introductionunclassified

Estudo Do Processo De Lixiviação Durante 40 Anos No Concreto De Enchimento Da Casa De Força Da Barragem Principal De Concreto De Itaipu

Santos¹,

Neumann²,

Faria³

et al. 2019

Memorias Conpat 2019

View full text Add to dashboard Cite

Este estudo tem como objetivo realizar uma análise do processo de lixiviação no concreto de enchimento da casa de força da usina hidrelétrica de Itaipu. Estudos anteriores realizados na década de 1980 estimaram o tempo aproximado de 140 anos para atingir uma perda admissível de 20% de cálcio do concreto e, além disso, indicaram estabilidade da estrutura. Avaliações químicas da água de percolação ao longo de 40 anos são apresentadas. Testemunhos de concreto foram recentemente extraídos para realizar análise de macro e microestrutura, os valores de resistência à compressão obtidos foram bastante superiores aos valores de projeto. Conclui-se que o processo de lixiviação ainda ocorre, em menor velocidade e que não há risco estrutural.

show abstract

Concrete alteration due to 55years of exposure to river water: Chemical and mineralogical characterisation

Cited by 30 publications

References 28 publications

Mineralogical Sequence of Self-Healing Products in Cracked Marine Concrete

Mineralogical Sequence of Self-Healing Products in Cracked Marine Concrete

The steel–concrete interface

Estudo Do Processo De Lixiviação Durante 40 Anos No Concreto De Enchimento Da Casa De Força Da Barragem Principal De Concreto De Itaipu

Contact Info

Product

Resources

About