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Volume 67 (2022): Issue 2 (December 2022)

Volume 66 (2022): Issue 1 (July 2022)

Volume 65 (2021): Issue 2 (December 2021)

Volume 64 (2021): Issue 1 (June 2021)

Volume 63 (2020): Issue 2 (December 2020)

Volume 62 (2020): Issue 1 (June 2020)

Volume 61 (2019): Issue 2 (December 2019)

Volume 60 (2019): Issue 1 (June 2019)

Volume 59 (2018): Issue 1 (December 2018)

Volume 58 (2018): Issue 1 (June 2018)

Journal Details
Format
Journal
eISSN
2545-2819
First Published
30 Sep 2018
Publication timeframe
2 times per year
Languages
English

Search

Volume 58 (2018): Issue 1 (June 2018)

Journal Details
Format
Journal
eISSN
2545-2819
First Published
30 Sep 2018
Publication timeframe
2 times per year
Languages
English

Search

10 Articles
Open Access

Long-term Influence of Concrete Surface and Crack Orientation on Self-healing and Ingress in Cracks – Field Observations

Published Online: 01 Dec 2018
Page range: 1 - 16

Abstract

Abstract

This paper presents results from investigations on the long-term influence of concrete surface and crack orientation on ingress in cracks. Five reinforced concrete structures from Norway exposed to either de-icing salts or seawater have been investigated. Concrete cores were taken with and without cracks from surfaces with vertical and horizontal orientation. Carbonation in cracks was found on all de-iced structures, and a crack on a completely horizontal surface appeared to facilitate chloride ingress. Ingress of substances from seawater was found in all cracks from marine exposure. However, the impact of cracks on chloride ingress was unclear. Horizontal cracks on vertical surfaces appeared to facilitate self-healing.

Keywords

  • Cracks
  • exposure
  • ingress
  • field observations
  • long-term
Open Access

Reduction of Radon Gas in Concrete Using Admixtures and Additives

Published Online: 01 Dec 2018
Page range: 17 - 34

Abstract

Abstract

The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined three concrete recipes where only an additive as well as fly ash were added as single constituents to a reference recipe and compared to a reference concrete. The inputs of an additive as well as a supplementary cementitious material (fly ash) were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete. Measurements were performed with an ATMOS 33 ionizing pulsation chamber for at least five different occasions for each recipe during a 22 month period. The results indicate a reduction of the exhalation rate by approximately 30-35 % for each altered recipe. This means roughly 1.5-2 mSv per year decrease in effective dose to a human using an additive or a supplementary cementitious material such as fly ash in relation to the investigated standard concrete.

Keywords

  • radon
  • effective dose
  • concrete
  • building materials
  • admixtures
  • additives
  • fly ash
  • health
Open Access

Frost Destruction of Concrete – A Study of the Validity of Different Mechanisms

Published Online: 01 Dec 2018
Page range: 35 - 54

Abstract

Abstract

Well-known frost destruction mechanisms applicable to concrete not exposed to salt are, (1) hydraulic pressure during freezing, (2) growth of ice-bodies in capillaries during freezing. Theories behind these mechanisms are presented. A third mechanism, ice expansion during heating of frozen concrete, is put forward. The validity of a certain mechanisms is discussed by analyzing its ability to explain experimental observations.

Keywords

  • Frost damage mechanisms
  • hydraulic pressure
  • ice growth
  • thermal deformation
Open Access

Full-scale Test of an Unreinforced Concrete Dome Plug for the Spent Nuclear Fuel Repository

Published Online: 01 Dec 2018
Page range: 55 - 75

Abstract

Abstract

In the planned Swedish repository for spent nuclear fuel, plugs are designed to close the deposition tunnels. The outer part of these plugs consists of a concrete dome made with self-compacting-concrete, designed to have low pH to reduce negative effects on the bentonite clay buffer. A full-scale test has been performed to evaluate the performance of the plug, to test the installation and to verify underlying design assumptions. In this paper, the behaviour of the concrete dome is evaluated based on measurements, from casting the concrete until it was subjected to 4 MPa hydrostatic water pressure.

Keywords

  • Nuclear
  • full-scale testing
  • concrete plug
  • shrinkage
  • cooling
Open Access

The Influence of Supplementary Cementitious Materials on Climate Impact of Concrete Structures Exposed to Chlorides

Published Online: 01 Dec 2018
Page range: 77 - 93

Abstract

Abstract

Addition of fly ash or GGBS in concrete has shown to increase the durability and thus the service life of concrete structures exposed to chlorides. Currently, the durability relies on regulations, which beside a minimum cover thickness also put constraint on amount and type of SCM in different environments. Swedish regulations do not, however, consider the actual durability of different binders. As a consequence, a LCA might be misleading. This paper investigates the climate impact of concrete with SCM in chloride environment. Current prescriptive design approach is compared with a performance based service life approach and applied to bridge parts.

Keywords

  • chloride induced corrosion
  • Supplementary Cementitious Materials (SCM)
  • climate impact
  • bridge
  • service life
  • LCA
  • concrete
Open Access

Dynamic Measurements for Determining Poisson’s Ratio of Young Concrete

Published Online: 01 Dec 2018
Page range: 95 - 106

Abstract

Abstract

Knowledge of the elastic properties of concrete at early age is often a pre-requisite for numerical calculations. This paper discusses the use of a laboratory technique for determining Poisson’s ratio at early concrete age. A non-destructive test set-up using the impact resonance method has been tested and evaluated. With the method, it has been possible to obtain results already at 7 hours of concrete age. Poisson’s ratio is found to decrease sharply during the first 24 hours to reach a value of 0.08 and then increase to approximately 0.15 after seven days.

Keywords

  • Modelling
  • testing
  • Poisson’s ratio
  • young concrete
Open Access

Filler and Water Reducer Effects on Sedimentation, Bleeding and Zeta-Potential of Cement Paste

Published Online: 01 Dec 2018
Page range: 107 - 125

Abstract

Abstract

Bleeding and sedimentation quantify the stability of fresh cement paste, whereas the addition of fillers and water reducers affect the stability. The effect of various types of fillers and water reducers was investigated by measuring bleeding, hydrostatic pressure and electroacoustic zeta-potential. Depending on their characteristics and use, fillers can improve stability by reducing sedimentation rate and bleeding. The combined effects of fillers and water reducers on the sedimentation rates, quantified as time-dependent hydrostatic pressure changes (dp/dt) in fresh matrix, correspond to their effects on zeta-potentials. The influence of the water reducers on sedimentation and bleeding exceed that of filler type.

Keywords

  • stability
  • sedimentation
  • bleeding
  • zeta-potential
  • filler
  • water reducer
Open Access

Continuous Preventive Bridge Maintenance of Swedish Municipalities – A Survey on Common Practice

Published Online: 01 Dec 2018
Page range: 127 - 142

Abstract

Abstract

As part of a report [1] on continuous preventive bridge maintenance, a survey was conducted with Swedish municipalities. The survey’s focus was on bridges and preventive maintenance, as well as the demands and performance control stated by the municipalities. The preventive maintenance the survey focused on was the annual maintenance concerning washing, cleaning of drainage system and removal of vegetation. The survey showed both similarities and differences within the municipalities but also in comparison with Swedish Transport Agency (STA).

Keywords

  • bridge maintenance
  • preventive maintenance
  • survey
Open Access

Towards the Understanding of the pH Dependency of the Chloride Binding of Portland Cement Pastes

Published Online: 01 Dec 2018
Page range: 143 - 162

Abstract

Abstract

Hydrated Portland cement paste exposed to a NaCl solution was acidified by adding HCl in small steps, gradually lowering the pH. The chloride binding of the cement paste changed as a function of the pH. For the range of pH from 13.2 to 12.2, decreasing pH resulted in a considerable increase in the chloride binding. At a pH of 11, the cement paste showed almost no chloride binding. In order to explain the changes in chloride binding upon lowering the pH, the phase assemblage was investigated with SEM-EDS, TGA and XRD and compared to a thermodynamic modelling.

Keywords

  • chloride binding
  • pH
  • C-S-H
  • thermodynamic modelling
  • leaching
Open Access

Prediction Models for Thermal Conductivity of Cement-based Composites

Published Online: 01 Dec 2018
Page range: 163 - 171

Abstract

Abstract

Cement-based materials are the most consumed materials in the construction industry. Low or high thermal conductive cement-based materials are of interest in applications such as embedded floor heating systems, building envelopes or structural elements. This paper describes prediction models for thermal conductivity of cementitious composites by considering different variables such as constituent materials, porosity and moisture content. The presented prediction models may be used for thermal conductivity based mix design of cementitious materials. Based on the desired accuracy, different solutions are proposed.

Keywords

  • Mix Design
  • Model
  • Thermal Conductivity
  • Cement-based Materials
10 Articles
Open Access

Long-term Influence of Concrete Surface and Crack Orientation on Self-healing and Ingress in Cracks – Field Observations

Published Online: 01 Dec 2018
Page range: 1 - 16

Abstract

Abstract

This paper presents results from investigations on the long-term influence of concrete surface and crack orientation on ingress in cracks. Five reinforced concrete structures from Norway exposed to either de-icing salts or seawater have been investigated. Concrete cores were taken with and without cracks from surfaces with vertical and horizontal orientation. Carbonation in cracks was found on all de-iced structures, and a crack on a completely horizontal surface appeared to facilitate chloride ingress. Ingress of substances from seawater was found in all cracks from marine exposure. However, the impact of cracks on chloride ingress was unclear. Horizontal cracks on vertical surfaces appeared to facilitate self-healing.

Keywords

  • Cracks
  • exposure
  • ingress
  • field observations
  • long-term
Open Access

Reduction of Radon Gas in Concrete Using Admixtures and Additives

Published Online: 01 Dec 2018
Page range: 17 - 34

Abstract

Abstract

The second largest cause of lung cancer is related to radon (222Rn) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of 238U from its constituents. The Swedish Cement and Concrete Research Institute (CBI) has examined three concrete recipes where only an additive as well as fly ash were added as single constituents to a reference recipe and compared to a reference concrete. The inputs of an additive as well as a supplementary cementitious material (fly ash) were made as a mean to investigate their potential influence on the radon exhalation rates of the concrete. Measurements were performed with an ATMOS 33 ionizing pulsation chamber for at least five different occasions for each recipe during a 22 month period. The results indicate a reduction of the exhalation rate by approximately 30-35 % for each altered recipe. This means roughly 1.5-2 mSv per year decrease in effective dose to a human using an additive or a supplementary cementitious material such as fly ash in relation to the investigated standard concrete.

Keywords

  • radon
  • effective dose
  • concrete
  • building materials
  • admixtures
  • additives
  • fly ash
  • health
Open Access

Frost Destruction of Concrete – A Study of the Validity of Different Mechanisms

Published Online: 01 Dec 2018
Page range: 35 - 54

Abstract

Abstract

Well-known frost destruction mechanisms applicable to concrete not exposed to salt are, (1) hydraulic pressure during freezing, (2) growth of ice-bodies in capillaries during freezing. Theories behind these mechanisms are presented. A third mechanism, ice expansion during heating of frozen concrete, is put forward. The validity of a certain mechanisms is discussed by analyzing its ability to explain experimental observations.

Keywords

  • Frost damage mechanisms
  • hydraulic pressure
  • ice growth
  • thermal deformation
Open Access

Full-scale Test of an Unreinforced Concrete Dome Plug for the Spent Nuclear Fuel Repository

Published Online: 01 Dec 2018
Page range: 55 - 75

Abstract

Abstract

In the planned Swedish repository for spent nuclear fuel, plugs are designed to close the deposition tunnels. The outer part of these plugs consists of a concrete dome made with self-compacting-concrete, designed to have low pH to reduce negative effects on the bentonite clay buffer. A full-scale test has been performed to evaluate the performance of the plug, to test the installation and to verify underlying design assumptions. In this paper, the behaviour of the concrete dome is evaluated based on measurements, from casting the concrete until it was subjected to 4 MPa hydrostatic water pressure.

Keywords

  • Nuclear
  • full-scale testing
  • concrete plug
  • shrinkage
  • cooling
Open Access

The Influence of Supplementary Cementitious Materials on Climate Impact of Concrete Structures Exposed to Chlorides

Published Online: 01 Dec 2018
Page range: 77 - 93

Abstract

Abstract

Addition of fly ash or GGBS in concrete has shown to increase the durability and thus the service life of concrete structures exposed to chlorides. Currently, the durability relies on regulations, which beside a minimum cover thickness also put constraint on amount and type of SCM in different environments. Swedish regulations do not, however, consider the actual durability of different binders. As a consequence, a LCA might be misleading. This paper investigates the climate impact of concrete with SCM in chloride environment. Current prescriptive design approach is compared with a performance based service life approach and applied to bridge parts.

Keywords

  • chloride induced corrosion
  • Supplementary Cementitious Materials (SCM)
  • climate impact
  • bridge
  • service life
  • LCA
  • concrete
Open Access

Dynamic Measurements for Determining Poisson’s Ratio of Young Concrete

Published Online: 01 Dec 2018
Page range: 95 - 106

Abstract

Abstract

Knowledge of the elastic properties of concrete at early age is often a pre-requisite for numerical calculations. This paper discusses the use of a laboratory technique for determining Poisson’s ratio at early concrete age. A non-destructive test set-up using the impact resonance method has been tested and evaluated. With the method, it has been possible to obtain results already at 7 hours of concrete age. Poisson’s ratio is found to decrease sharply during the first 24 hours to reach a value of 0.08 and then increase to approximately 0.15 after seven days.

Keywords

  • Modelling
  • testing
  • Poisson’s ratio
  • young concrete
Open Access

Filler and Water Reducer Effects on Sedimentation, Bleeding and Zeta-Potential of Cement Paste

Published Online: 01 Dec 2018
Page range: 107 - 125

Abstract

Abstract

Bleeding and sedimentation quantify the stability of fresh cement paste, whereas the addition of fillers and water reducers affect the stability. The effect of various types of fillers and water reducers was investigated by measuring bleeding, hydrostatic pressure and electroacoustic zeta-potential. Depending on their characteristics and use, fillers can improve stability by reducing sedimentation rate and bleeding. The combined effects of fillers and water reducers on the sedimentation rates, quantified as time-dependent hydrostatic pressure changes (dp/dt) in fresh matrix, correspond to their effects on zeta-potentials. The influence of the water reducers on sedimentation and bleeding exceed that of filler type.

Keywords

  • stability
  • sedimentation
  • bleeding
  • zeta-potential
  • filler
  • water reducer
Open Access

Continuous Preventive Bridge Maintenance of Swedish Municipalities – A Survey on Common Practice

Published Online: 01 Dec 2018
Page range: 127 - 142

Abstract

Abstract

As part of a report [1] on continuous preventive bridge maintenance, a survey was conducted with Swedish municipalities. The survey’s focus was on bridges and preventive maintenance, as well as the demands and performance control stated by the municipalities. The preventive maintenance the survey focused on was the annual maintenance concerning washing, cleaning of drainage system and removal of vegetation. The survey showed both similarities and differences within the municipalities but also in comparison with Swedish Transport Agency (STA).

Keywords

  • bridge maintenance
  • preventive maintenance
  • survey
Open Access

Towards the Understanding of the pH Dependency of the Chloride Binding of Portland Cement Pastes

Published Online: 01 Dec 2018
Page range: 143 - 162

Abstract

Abstract

Hydrated Portland cement paste exposed to a NaCl solution was acidified by adding HCl in small steps, gradually lowering the pH. The chloride binding of the cement paste changed as a function of the pH. For the range of pH from 13.2 to 12.2, decreasing pH resulted in a considerable increase in the chloride binding. At a pH of 11, the cement paste showed almost no chloride binding. In order to explain the changes in chloride binding upon lowering the pH, the phase assemblage was investigated with SEM-EDS, TGA and XRD and compared to a thermodynamic modelling.

Keywords

  • chloride binding
  • pH
  • C-S-H
  • thermodynamic modelling
  • leaching
Open Access

Prediction Models for Thermal Conductivity of Cement-based Composites

Published Online: 01 Dec 2018
Page range: 163 - 171

Abstract

Abstract

Cement-based materials are the most consumed materials in the construction industry. Low or high thermal conductive cement-based materials are of interest in applications such as embedded floor heating systems, building envelopes or structural elements. This paper describes prediction models for thermal conductivity of cementitious composites by considering different variables such as constituent materials, porosity and moisture content. The presented prediction models may be used for thermal conductivity based mix design of cementitious materials. Based on the desired accuracy, different solutions are proposed.

Keywords

  • Mix Design
  • Model
  • Thermal Conductivity
  • Cement-based Materials

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