Model for practical carbonation depth prediction for high volume fly ash concrete and recycled aggregate concrete

Carević, Vedran; Ignjatović, Ivan; Dragaš, Jelena

doi:10.1016/j.conbuildmat.2019.03.267

Cited by 68 publications

(29 citation statements)

References 45 publications

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“…Therefore, the analysis of possible modifications of this model to be applicable for green concretes started with an analysis of this parameter. The relationship between R −1 NAT and R −1 ACC for FAC was proposed by Carević et al 6 The previously formed database 6 was expanded with results from investigations in which 20 to 40 percentage of cement was replaced with FA 24–26 . Based on the expanded database, the corrected values of the regression coefficient k t and error term ε t were presented in this study.…”

Section: Modification Of the Proposed Model For Application In Rac Anmentioning

confidence: 99%

Evaluation of concrete cover depth for green concretes exposed to carbonation

Carević

Ignjatović

2020

Structural Concrete

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Carbonation resistance of fly ash concrete (FAC) and recycled aggregate concrete (RAC) has been extensively tested in the past decade, but there are still no recommendations for their application in codes of practice. Therefore, the main objective of this study was to determine the minimum concrete cover depth of RAC and FAC exposed to carbonation to satisfy the required service life. In this study, the relationship between concrete compressive strength at 28 days (fcm) and inverse effective carbonation resistance (R−1ACC) was established. The analysis was carried out on all data available in the literature in order to establish this relationship for FAC and RAC made with different replacement percentages. After establishing a relationship between R−1ACC and fcm, a prediction of the service life was made using the fib‐Bulletin 34 (2006, Model code for service life design (1st ed.). Lausanne: International Federation for Structural Concrete (fib)) prediction model for all exposure classes to carbonation. For same concrete class, it can be concluded that in the case of RAC there was no significant difference in the duration of the service life compared with natural aggregate concrete, even at 100% replacement of natural aggregate with recycled ones. For concrete up to 35% of fly ash in total cementitious materials, concrete cover for satisfying the required service life of 50 years was 40% higher compared with Portland cement concrete, and more than two times higher in case of concrete with 40–70% fly ash.

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Section: Modification Of the Proposed Model For Application In Rac Anmentioning

confidence: 99%

Evaluation of concrete cover depth for green concretes exposed to carbonation

Carević

Ignjatović

2020

Structural Concrete

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“…The slab width was taken as 1,000 mm (i.e., 1 m strip of a one‐way slab), while the slab height, h , was varied as 200 and 300 mm. Assuming exposure class XC1, the reinforcement center of gravity, d 1 , was taken as 30 mm for NAC and RAC25, but was increased to 35 mm for RAC50 (i.e., concrete cover was increased by 5 mm), consistent with findings on the reduced carbonation resistance of RAC 7,44 . As the aim of the study was to assess the deflections of RAC elements considering design guidelines proposed for practice, the increased cover for RAC50 was considered appropriate.…”

Section: Parametric Study On Long‐term Deflections Of Reinforced Rac mentioning

confidence: 99%

“…Because of the extremely high water absorption of fine RCA (≤4 mm), studies have mostly focused on RAC in which coarse NA is replaced with coarse RCA (>4 mm). In terms of the main mechanical‐ and durability‐related properties, the effects of RCA on the compressive and tensile strengths of concrete are moderate, 11 with slightly lower resistance to carbonation 7 . However, the effects are much greater in decreased modulus of elasticity of RAC, 12 and in terms of time‐dependent properties such as creep and shrinkage strains, both of which increase significantly with RCA content in RAC 13–15 …”

Section: Introductionmentioning

confidence: 99%

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Parametric numerical study on service‐load deflections of reinforced recycled aggregate concrete slabs and beams based on fib Model Code 2010

Tošić

Kurama

2020

Structural Concrete

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Recycled aggregate concrete (RAC) is entering into structural design codes such as the new Eurocode 2. However, serviceability limit state (SLS) behavior of RAC, especially deflections, can be significantly greater than for natural aggregate concrete. Proposals for deflection control of RAC exist, but there still have not been significant studies on their implications for SLS design. In this paper, a comprehensive numerical parametric study on the sustained service‐load deflections of reinforced RAC slabs and beams is described. First, a concrete material model for the time‐dependent analysis of reinforced concrete structures is described, validated, and calibrated, incorporating fib Model Code 2010 creep and shrinkage models in the OpenSees structural analysis program. Then, service‐load deflection analyses are conducted on RAC one‐way slabs and T‐beams considering the amount of coarse recycled concrete aggregate (RCA), concrete strength class, element height, span, statical system, relative humidity, and quasi‐permanent load‐to‐design load ratio. The results show that RCA begins to have an appreciable effect on deflections only for coarse aggregate replacement percentages above 25%. At 50% replacement, the maximum spans to satisfy deflection limits can be considerably reduced; however, these reductions are smaller for T‐beams and higher class concrete. The results confirm the versatility of the numerical model, as well as the applicability and limitations of RAC in SLS design.

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“…(2019) [14], Ghorbani at al. (2019) [15], Carevic (2019) [16], Hussain at al. (2017) [17], Cai-feng Lu at al.…”

Section: Introductionmentioning

confidence: 99%

Prediction of Carbonation Progress in Concrete Containing Calcareous Fly Ash Co-Binder

2019

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According to the European Standards (EN 450-1, EN 206), it is not permissible to use calcareous fly ash as an additive to concrete. However, other standards (for example, the American and Canadian ones) allow the use of high-calcium fly ash (type C) in concrete. As a result of brown coal combustion, a large amount of this type of fly ash is produced, and considerations on their use in concrete are in progress. Research into the influence of high-calcium fly ash on concrete durability is fundamental for dealing with that issue. The aim of the present research was to develop a new model of carbonation over time, also including calcareous fly ash content in the binder. The self-terminating model of carbonation is new, and not developed by other authors. In the current research, the former simplest model (a function of w/c ratio and time) is expanded with the calcareous fly ash to cement ratio. The basis is a statistically planned experiment with a large scope of two material variables (w/c ratio and fly ash to cement ratio). The main measured property is the carbonation depth after exposure to 4% of CO2 concentration (according to CEN/TS 12390-12). The model of carbonation obtained from this experiment is an output of the paper. Also, the idea of developing similar models for concrete families as a tool for designing concrete cover thickness for reinforced elements is described in the paper.

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Model for practical carbonation depth prediction for high volume fly ash concrete and recycled aggregate concrete

Cited by 68 publications

References 45 publications

Evaluation of concrete cover depth for green concretes exposed to carbonation

Evaluation of concrete cover depth for green concretes exposed to carbonation

Parametric numerical study on service‐load deflections of reinforced recycled aggregate concrete slabs and beams based on fib Model Code 2010

Prediction of Carbonation Progress in Concrete Containing Calcareous Fly Ash Co-Binder

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