The influence of internal relative humidity on the rate of corrosion of steel embedded in concrete and mortar

Enevoldsen, J.N.; Hansson, C.M.; Hope, Brian B.

doi:10.1016/0008-8846(94)90122-8

Cited by 61 publications

(36 citation statements)

References 7 publications

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“…However, in addition to cover thickness, the rate of diffusion of oxygen and CO 2 is also controlled by the degree of pore saturation in the concrete cover [3][4][5]. It has been shown that the strength of the concrete does not necessarily reflect the durability of the concrete [6].…”

Section: Introductionmentioning

confidence: 99%

“…The combination of these reactions form the basis of corrosion products, namely Fe(OH) 2 . Further reactions with oxygen and water present in the cover might form Fe(OH) 3 [7], which is of greater volume than the steel. This increase in volume exerts stresses within the concrete, resulting in localised microcracking once the tensile capacity has been exceeded.…”

Section: Introductionmentioning

confidence: 99%

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Cover zone properties influencing acoustic emission due to corrosion

Ing

Austin

Lyons

2005

Cement and Concrete Research

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The deterioration of reinforced concrete is a serviceability problem world-wide. The cover zone plays an important role in the durability and serviceability of concrete and provides the initial barrier to aggressive species. The research presented investigates the potential of acoustic emission (AE) as a means of identifying corrosion at an early stage, before any significant cover damage has occurred. The purpose of part of the study was to identify the influential cover zone factors that affect the magnitude of the acoustic emission measurements per gram of steel loss. Prisms with various combinations of strength, cover thickness, aggregate and rebar diameters were studied to ascertain the important variables likely to be encountered on reinforced structures.The experimental results confirmed that early corrosion, verified by internal visual inspection and mass loss, can be detected by AE and before any external signs of cracking. They also show that the most influential parameter affecting the AE measurement is concrete strength, being exponentially related to the AE Energy.Material properties such as cover thickness had a negligible effect on AE Energy during the initial stages of reinforcement corrosion, whereas from this initial work, the rebar diameter indicated a promising relationship with AE Energy per gram of steel loss.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cover zone properties influencing acoustic emission due to corrosion

Ing

Austin

Lyons

2005

Cement and Concrete Research

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“…This would promote development and continuation of the corrosion process. As mentioned above, the presence of water leads to dissolution of the chlorides deposited on the concrete surface and would facilitate their transport and propagation throughout the structure (Enevoldsen et al, 1994). The seriousness of this corrosion threat depends on the amount time the structure remains wet.…”

Section: Resultsmentioning

confidence: 99%

“…If RH falls below 80%, cement hydration can actually cease (Enevoldsen et al, 1994). In contrast, the presence of moisture at intermediate and later ages can cause concrete to deteriorate.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, curing time and the water/cement ratio (w/c) were found to have little influence on internal RH profiles (Parrot, 1991). A critical RH may exist for steel corrosion onset (Enevoldsen et al, 1994), perhaps 80% under laboratory conditions and 70% in field conditions. Finally, when a concrete contains chlorides, external environment RH is normally lower than internal RH (Andrade et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

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Time of Wetness and HR-T Complex as Tools for Corrosion Risk Evaluation in a Concrete Block Exposed to a Humid Tropical Environment

Castro-Borges

Véleva

2015

Revista de la Construcción

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Tiempo de Humectación y el Complejo HR-T como herramientas para evaluar el riesgo por corrosión en un bloque de concreto expuesto a un ambiente tropical húmedoPedro Castro-Borges ( Abstract Material surface time of wetness (TOW) and temperature (T) are critical variables that influence the corrosion behavior of reinforced steel bars in concrete, and concrete durability. In concrete structures, both variables are indirectly dependent on the atmospheric relative humidity/ temperature complex, and specific structural characteristics: concrete composition, water/cement ratio, curing time, geometry and orientation in the environment. Concrete internal TOW and T distribution data were collected using Cu/Au electronic sensors arranged at 15, 40, 65 and 75 mm depths in a concrete block (300 x 300 x 150 mm; w/c 0.5) exposed for one year in a rural-urban humid tropical climate in southeast Mexico. Concrete internal TOW allows structure designers to define concrete cover thickness over steel reinforcement bars. The results indicate that under the tested exposure conditions, the side of the block with the highest TOW values (west) would require a thicker concrete cover than that with lower values (east). Longer TOW can increase the possible permeation of gases such as CO2, and consequent concrete carbonation, as well as lead to loss of the passive state in steel reinforcement and initiation of the corrosion process. ResumenEl tiempo de humectación (TOW) y la temperatura (T) de la superficie de un material son variables críticas que influencian el comportamiento corrosivo del acero de refuerzo en el concreto y su durabilidad. Estos factores tienen una dependencia indirecta del complejo atmosférico humedad relativa/temperatura, debido a las características específicas del concreto: composición, relación agua/cemento (w/c), tiempo de curado, geometría y orientación en el ambiente. Con el objetivo de adquirir datos para la distribución interna del TOW y T, se colocaron sensores electrónicos de Au/Cu a diferentes profundidades de 15, 49, 65 y 75 mm en un bloque de concreto (300x300x150 mm; w/c 0.5), expuesto durante un año en clima rural-urbano tropical húmedo, del sureste de México. El TOW registrado en el bloque de concreto es importante para diseñadores de estructuras, para definir el espesor del concreto sobre el refuerzo. Los resultados obtenidos mostraron que en las condiciones de esta exposición, la cara oeste del concreto debería ser más gruesa que la orientada al este. La existencia de un largo TOW causará una mayor posibilidad de entrada de gases como CO2, lo cual conllevaría a carbonatación del concreto, pérdida de la capa pasiva del acero e inicio de su corrosión.

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Influence of temperature and humidity on Portland cement mortar resistivity monitored with inner sensors

Zaccardi

Garcia

Huélamo

et al. 2009

Materials & Corrosion

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Concrete resistivity is directly related to relative humidity (RH) and is also affected by temperature. In this paper, a theoretical discussion about how these two factors affect resistivities of concrete and mortar is provided. Moreover, experimental results on sensorized mortar probes are presented and correlated to analytical models of temperature and humidity influences. All measurements were performed under controlled conditions. Temperature, RH, and resistivity were measured simultaneously in a particular zone of the probes. Temperature scanning was performed over short periods of time (approximately 1 h) and the probes were covered with waterproof paraffin each time for constant humidity content. This was feasible as all sensors were embedded. Water contents were ensured during the experiment by weighting the probes. Conclusions on the applicability of these techniques, their advantages, and limitations, and correlation to Archie and Arrhenius laws of the results are made.

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The influence of internal relative humidity on the rate of corrosion of steel embedded in concrete and mortar

Cited by 61 publications

References 7 publications

Cover zone properties influencing acoustic emission due to corrosion

Cover zone properties influencing acoustic emission due to corrosion

Time of Wetness and HR-T Complex as Tools for Corrosion Risk Evaluation in a Concrete Block Exposed to a Humid Tropical Environment

Influence of temperature and humidity on Portland cement mortar resistivity monitored with inner sensors

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