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Tobias Danner
MSc, PhD, Research Scientist, SINTEF Community, Department Architecture, Materials and Structures , NO-7491 Trondheim

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Journal article
Published: 01 June 2020 in Nordic Concrete Research
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This study investigates the feasibility of using bauxite residue (BR) as supplementary cementitious material (SCM) for the cement and concrete industry. It is shown from pastes of BR and calcium hydroxide, that BR is highly pozzolanic in nature. The early hydration of cement pastes with BR is accelerated while long-term strength is reduced probably due to the alkaline nature of BR. To be used as cement replacement material in concrete, attempts have been made to reduce the alkali content of BR, in particular to reduce the chance of alkali-aggregate reactions. Co-calcination of BR with kaolin or washing and cooking of BR with calcium hydroxide or calcium hydroxide and gypsum resulted in considerable reduction of alkali content; up to 75%. At the same time the reactivity of the BR was reduced but still being higher compared to fly ash already used in the cement industry.

ACS Style

Tobias Danner; Harald Justnes. Bauxite Residue as Supplementary Cementitious Material – Efforts to Reduce the Amount of Soluble Sodium. Nordic Concrete Research 2020, 62, 1 -20.

AMA Style

Tobias Danner, Harald Justnes. Bauxite Residue as Supplementary Cementitious Material – Efforts to Reduce the Amount of Soluble Sodium. Nordic Concrete Research. 2020; 62 (1):1-20.

Chicago/Turabian Style

Tobias Danner; Harald Justnes. 2020. "Bauxite Residue as Supplementary Cementitious Material – Efforts to Reduce the Amount of Soluble Sodium." Nordic Concrete Research 62, no. 1: 1-20.

Journal article
Published: 01 June 2020 in Nordic Concrete Research
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Several inspection methods can be used to assess the corrosion state of steel reinforcement in concrete. Especially for periodical field surveys and monitoring, non-destructive testing (NDT) methods are to be preferred as they do not cause any or very limited damage to the existing concrete. In this paper, the corrosion state of three reinforced concrete beams exposed to marine environment for 25 years was evaluated by measuring three parameters; electrochemical potential, concrete resistivity and corrosion rate. The measurements were performed with commercial devices. It was found that all devices are applicable for field inspections. Among the methods selected for the study, the electrochemical potential measured in a fine grid and analysed statistically offered the best possibility of evaluating the corrosion state; preferably in combination with selected excavations for determination of the level of corrosion.

ACS Style

Hornbostel Karla; Tobias Danner; Mette Rica Geiker. Non-destructive Test Methods for Corrosion Detection in Reinforced Concrete Structures. Nordic Concrete Research 2020, 62, 41 -61.

AMA Style

Hornbostel Karla, Tobias Danner, Mette Rica Geiker. Non-destructive Test Methods for Corrosion Detection in Reinforced Concrete Structures. Nordic Concrete Research. 2020; 62 (1):41-61.

Chicago/Turabian Style

Hornbostel Karla; Tobias Danner; Mette Rica Geiker. 2020. "Non-destructive Test Methods for Corrosion Detection in Reinforced Concrete Structures." Nordic Concrete Research 62, no. 1: 41-61.

Conference paper
Published: 14 April 2020 in High Performance Fiber Reinforced Cement Composites 6
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The pozzolanic reactivity of four calcined natural clays (two being rich in illite and two being rich in smectite) was investigated by means of 28 days compressive strength of mortars and calcium hydroxide (CH) consumption in pastes of calcined clay and CH. The materials were characterized by XRD, XRF, BET, SEM and TG/DTG. Hydrated pastes of clay and CH were investigated by means of XRD, DTG and SEM. Besides clay minerals, two of the investigated raw clays contained 15 and 25% calcite, respectively. At optimum calcination temperature, calcined clays containing smectite and calcite, and illite and calcite in the raw clay had higher pozzolanic reactivity than clays containing smectite and illite alone. Results indicate that in clays containing high amounts of calcite, the formation of a glass phase upon calcination contributes to the pozzolanic reactivity.

ACS Style

Tobias Danner; Geir Norden; Harald Justnes. The Effect of Calcite in the Raw Clay on the Pozzolanic Activity of Calcined Illite and Smectite. High Performance Fiber Reinforced Cement Composites 6 2020, 131 -138.

AMA Style

Tobias Danner, Geir Norden, Harald Justnes. The Effect of Calcite in the Raw Clay on the Pozzolanic Activity of Calcined Illite and Smectite. High Performance Fiber Reinforced Cement Composites 6. 2020; ():131-138.

Chicago/Turabian Style

Tobias Danner; Geir Norden; Harald Justnes. 2020. "The Effect of Calcite in the Raw Clay on the Pozzolanic Activity of Calcined Illite and Smectite." High Performance Fiber Reinforced Cement Composites 6 , no. : 131-138.

Journal article
Published: 10 May 2019 in Minerals
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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.

ACS Style

Tobias Danner; Ulla Hjorth Jakobsen; Mette Rica Geiker. Mineralogical Sequence of Self-Healing Products in Cracked Marine Concrete. Minerals 2019, 9, 284 .

AMA Style

Tobias Danner, Ulla Hjorth Jakobsen, Mette Rica Geiker. Mineralogical Sequence of Self-Healing Products in Cracked Marine Concrete. Minerals. 2019; 9 (5):284.

Chicago/Turabian Style

Tobias Danner; Ulla Hjorth Jakobsen; Mette Rica Geiker. 2019. "Mineralogical Sequence of Self-Healing Products in Cracked Marine Concrete." Minerals 9, no. 5: 284.

Journal article
Published: 05 April 2019 in European Journal of Environmental and Civil Engineering
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ACS Style

Tobias Danner; Geir Norden; Harald Justnes. Calcareous smectite clay as a pozzolanic alternative to kaolin. European Journal of Environmental and Civil Engineering 2019, 1 -18.

AMA Style

Tobias Danner, Geir Norden, Harald Justnes. Calcareous smectite clay as a pozzolanic alternative to kaolin. European Journal of Environmental and Civil Engineering. 2019; ():1-18.

Chicago/Turabian Style

Tobias Danner; Geir Norden; Harald Justnes. 2019. "Calcareous smectite clay as a pozzolanic alternative to kaolin." European Journal of Environmental and Civil Engineering , no. : 1-18.

Journal article
Published: 01 December 2018 in Nordic Concrete Research
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Calcined clays are gaining increasing interest as future supplementary cementitious materials for the production of blended cements. Besides the mineralogy, the right production conditions can affect the pozzolanic activity of calcined clays. In this paper, the pozzolanic reactivity of two calcined natural clays in dependence of burning temperature, residence time in the furnace, cooling conditions and particle size of the final product is investigated. The highest pozzolanic reactivity was found at calcination temperatures between 600 and 800°C. While different cooling conditions had no identified effect on reactivity, decreased particle size and residence time increased the reactivity.

ACS Style

Tobias Danner; Harald Justnes. The Influence of Production Parameters on Pozzolanic Reactivity of Calcined Clays. Nordic Concrete Research 2018, 59, 1 -12.

AMA Style

Tobias Danner, Harald Justnes. The Influence of Production Parameters on Pozzolanic Reactivity of Calcined Clays. Nordic Concrete Research. 2018; 59 (1):1-12.

Chicago/Turabian Style

Tobias Danner; Harald Justnes. 2018. "The Influence of Production Parameters on Pozzolanic Reactivity of Calcined Clays." Nordic Concrete Research 59, no. 1: 1-12.

Journal article
Published: 01 September 2018 in Applied Clay Science
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ACS Style

Tobias Danner; Geir Norden; Harald Justnes. Characterisation of calcined raw clays suitable as supplementary cementitious materials. Applied Clay Science 2018, 162, 391 -402.

AMA Style

Tobias Danner, Geir Norden, Harald Justnes. Characterisation of calcined raw clays suitable as supplementary cementitious materials. Applied Clay Science. 2018; 162 ():391-402.

Chicago/Turabian Style

Tobias Danner; Geir Norden; Harald Justnes. 2018. "Characterisation of calcined raw clays suitable as supplementary cementitious materials." Applied Clay Science 162, no. : 391-402.

Journal article
Published: 01 June 2018 in Nordic Concrete Research
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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.

ACS Style

Tobias Danner; Mette Rica Geiker. Long-term Influence of Concrete Surface and Crack Orientation on Self-healing and Ingress in Cracks – Field Observations. Nordic Concrete Research 2018, 58, 1 -16.

AMA Style

Tobias Danner, Mette Rica Geiker. Long-term Influence of Concrete Surface and Crack Orientation on Self-healing and Ingress in Cracks – Field Observations. Nordic Concrete Research. 2018; 58 (1):1-16.

Chicago/Turabian Style

Tobias Danner; Mette Rica Geiker. 2018. "Long-term Influence of Concrete Surface and Crack Orientation on Self-healing and Ingress in Cracks – Field Observations." Nordic Concrete Research 58, no. 1: 1-16.

Journal article
Published: 01 January 2016 in Cement and Concrete Research
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The early age phase development during the hydration of C3A–gypsum pastes with 1 and 4% Ca- or Na-lignosulfonate (CLS and NLS) was investigated using isothermal calorimetry, in-situ XRD, thermogravimetry, mass spectroscopy, and SEM analysis. With 1% CLS or NLS neither retardation of C3A dissolution nor retardation of ettringite formation was observed. When LS was added in a concentration of 4%, C3A and gypsum dissolution were slightly retarded. Gypsum depletion was delayed in all pastes containing CLS or NLS. 1% CLS or NLS increased the amount of AFm-phases formed within 24 h, while the amount of AFm was reduced with 4% CLS or NLS. The initial heat flow increased and the heat flow in the gypsum depletion peak was reduced with 1 and 4% CLS. With 4% NLS no initial heat flow was measured and the heat developed slowly within the first 15 min of hydration in the C3A–gypsum paste.

ACS Style

Tobias Danner; Harald Justnes; Mette Rica Geiker; Rolf Andreas Lauten. Early hydration of C 3 A–gypsum pastes with Ca- and Na-lignosulfonate. Cement and Concrete Research 2016, 79, 333 -343.

AMA Style

Tobias Danner, Harald Justnes, Mette Rica Geiker, Rolf Andreas Lauten. Early hydration of C 3 A–gypsum pastes with Ca- and Na-lignosulfonate. Cement and Concrete Research. 2016; 79 ():333-343.

Chicago/Turabian Style

Tobias Danner; Harald Justnes; Mette Rica Geiker; Rolf Andreas Lauten. 2016. "Early hydration of C 3 A–gypsum pastes with Ca- and Na-lignosulfonate." Cement and Concrete Research 79, no. : 333-343.

Journal article
Published: 01 March 2015 in Cement and Concrete Research
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ACS Style

Tobias Danner; Harald Justnes; Mette Geiker; Rolf Andreas Lauten. Phase changes during the early hydration of Portland cement with Ca-lignosulfonates. Cement and Concrete Research 2015, 69, 50 -60.

AMA Style

Tobias Danner, Harald Justnes, Mette Geiker, Rolf Andreas Lauten. Phase changes during the early hydration of Portland cement with Ca-lignosulfonates. Cement and Concrete Research. 2015; 69 ():50-60.

Chicago/Turabian Style

Tobias Danner; Harald Justnes; Mette Geiker; Rolf Andreas Lauten. 2015. "Phase changes during the early hydration of Portland cement with Ca-lignosulfonates." Cement and Concrete Research 69, no. : 50-60.