Harald Justnes

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Verified

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• PhD
• Principal Investigator at SINTEF

The process of concrete development requires extensive water use, leading to a scarcity of natural freshwater supplies. It was found that nearly 19% of the overall water is consumed by industrial fields in which the construction field takes the lead. Employing seawater for concrete construction activities could help in protecting vital freshwater s...

The impact of novel supplementary cementitious materials (SCMs) on the phase assemblage and the pore structure in cement pastes was studied and linked to their impact on the compressive strength in mortar. The composite cements analysed had a composition of 78 wt.% Portland cement, 18 wt.% SCM and 4 wt.% limestone filler, and the samples were cured...

The objective is to elucidate the effect of calcium nitrate CN on cement replaced with 50% blastfurnace slag (ggbs). The influence of 2 and 4% CN accelerator on hydration development of these binders were investigated by isothermal calorimetry, X-ray diffraction and thermogravimetry. The strength development of mortar with two different ggbs blende...

DARE2C (Durable Aluminium Reinforced Environmentally-friendly Concrete Construction) project is to develop a more environmental-friendly concrete and use aluminium (Al) as reinforcement material, instead of steel. The new concrete uses supplementary cementitious materials (SCM), which provides a low alkaline environment suitable for aluminium reinf...

Portland cement has been replaced with 50% ground, granulated blastfurnace slag (ggbs) of two types. The influence of 2 and 4% calcium nitrate accelerator on early hydration of such binders was investigated by isothermal calorimetry as well as X-ray diffraction and thermogravimetry. The strength development of mortar based on these binder blends ha...

About 20 different alternative Nordic SCMs were examined with the aim to be used in future cement products with high clinker replacement. The materials were screened regarding practical production considerations, composition, chemical reactivity, strength development and durability parameters. After the overall assessment natural volcanic pozzolan...

Accelerated testing of alkali silica reaction (ASR) in concrete at elevated temperatures of 38 and 60 ◦C has an unknown impact on the alkali metal distribution in the cement paste. This paper investigates how the alkali metals released from hydrating Portland cement, limestone, and SCMs distribute between non-reactive and unreacted phases, C-A-S-H,...

Hardening of Portland cement-based materials in vicinity of electrically conductive surfaces, especially when the surfaces are electrically or galvanically polarized, can lead to both morphological and chemical changes in cement close to the surfaces due to combined electrochemical and electrophysical processes. Cement hydration products close to g...

Reinforced concrete is one of the most important structural materials currently used for buildings and infrastructure, in which corrosion of the reinforcement is vital in the design, lifetime, and cost. Replacing steel with aluminium reinforcements is interesting from both a design and environmental standpoint. Conventional cement causes damage to...

Five different natural clays from Portugal were calcined between 700-800 ºC and evaluated with regard to their potential to be used as SCM in cementitious binders. Originally used for production of lightweight aggregates, 3 kaolinitic clays were compared to a smectite and illite rich clay. As expected, the kaolinitic clays showed highest reactivity...

Synopsis: The long-term stability of aluminum metal in binders intended for concrete has been studied. Aluminum was cast in paste where 55% cement was replaced by calcined smectitic clay. After 7 days curing several samples were submersed in either distilled water or in 6% NaCl solution. After 1 year of submersion, the microstructure of samples sub...

Concrete with 55% cement replacement by calcined clay has been made with the purpose of stabilizing aluminium reinforcement, to lower the over-all carbon-footprint and allow unusual long service life without maintenance. The long service life is guaranteed since aluminium is stable in a carbonated system and in presence of chlorides. In addition, t...

Mortar specimens were exposed to either a 3% NaCl solution or a 3% NaCl+KOH solution for up to 180 days. Exposure to the NaCl solution provoked much more leaching than the NaCl+KOH exposure. Leaching strongly impacted the chloride ingress profiles. The extended leaching led to a maximum total chloride content almost three times higher and a deeper...

In traditional reinforced concrete, the alkaline pore solution which passivates the steel rebars will get neutralized with time in an exposed environment. Therefore, to prevent corrosion initiation, the permeability of the concrete is reduced and extra-thick concrete covers the steel rebars. Aluminum is passive in the neutralized environment, but t...

Portlan cement were made by mixing 4 different clinkers with 2 gypsum levels and 0-5% limestone powder. The compressive strength after 28 days varied from 40-70 MPa for mortar with equal w/c. Some of the clinkers were mixed 4 diferent fly ashes and the response to strength varied. To explain the large differences in strength evolution, the clinker...

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is pres...

Bauxite residue is a major waste stream available in large volumes globally that can cause risks to the surrounding environment (e.g. ecotoxicity) when disposed and stored by conventional methods. There is yet no large-scale application and the utilization as supplementary cementitious material might be the best way to re-use bauxite residue. The m...

Calcium oxide (CaO), also known as burnt lime, is being considered as a possible treatment to reduce the negative impact of sea urchins on tare forests in northern coastal waters and blue-green algal blooms in the surrounding of fish-farms. In this respect, the reaction kinetics of burnt lime in contact with sea water has been elucidated and compar...

The reaction kinetics of burnt lime (CaO) in contact with sea water has been elucidated and compared to its behaviour in fresh water. In the first minutes of contact between burnt lime and water, it "slaked" as CaO reacted with water to yield calcium hydroxide (Ca(OH)2). Subsequently, calcium hydroxide reacted with magnesium, sulphate and carbonate...

The microstructural changes of paste, mortar and concrete based on Portland and fly ash containing Portland composite cements caused by carbonation have been studied. The objective was to find out why fly ash containing mortars carbonate with double rate of the neat Portland cement mortars. The reason is partly because they contain less calcium con...

The reaction kinetics of burnt lime (CaO) in contact with sea water has been elucidated and compared to its behaviour in fresh water. In the first minutes of contact between burnt lime and water, it "slaked" as CaO reacted with water to yield calcium hydroxide (Ca(OH)2). Subsequently, calcium hydroxide reacted with magnesium, sulphate and carbonate...

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...

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 a...

Tourism is a very important contributor to Goa’s GDP. In 2017, 6.9 million domestic tourists and 0.89 million foreign tourists visited Goa. This leads to a need for refurbishment of hotel rooms which is a significant contributor to the C&D waste generation in Goa. Around one ton of waste is on average generated per rehabilitated hotel room. The con...

Amorphous carbon powder (ACP) is a hydrophobic by-product material from refining waste materials of paraffin production factory. ACP effects on permeability and mechanical properties of cementitious composites were investigated. A range of properties of modified cement paste and concrete including hydrophobicity, workability, porosity, compressive...

The pozzolanic reactivity of 4 calcined natural clays (2 being rich in illite and 2 being rich in smectite) was investigated by means of 28 days com-pressive 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...

Tourism is a very important contributor to Goa's GDP. In 2017, 6.9 million domestic tourists and 0.89 million foreign tourists visited Goa. This leads to a need for refurbishment of hotel rooms which is a significant contributor to the C&D waste generation in Goa. Around one ton of waste is on average generated per rehabilitated hotel room. The con...

This paper presents work being carried out in Work Package 3 of TIGHT (True Improvement in Grouting High pressure Technology for tunnelling) project. The objective is to investigate flow and mechanical properties of three cements (A, B and C) at actual tunnel- and room –temperatures using various laboratory methods. The cements were first character...

The hydration of cement pastes with addition of a kaolinite rich clay (Clay A) and a calcareous smectite rich clay (Clay B) was investigated with isothermal calorimetry, in-situ XRD, PXRD, TGA and EPMA. Portland cement was replaced by 20, 35 and 50 weight% calcined clay in cement pastes and mortars. Both clays showed good pozzolanic reactivity. How...

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...

The construction of steel lining system for concrete fuel storage tanks can lead to increase in construction cost and duration. The current research seeks the alternative of storing hydrocarbon products in concrete tanks without a liner. The primary degradation mechanism for concrete in direct contact with hydrocarbon products is caused by the acid...

The potential use of two raw clays (Clay A: kaolin; Clay B: calcareous montmorillonite) as supplementary cementitious material (SCM) in blended cements was investigated. Cement replacement in mortars by 20% calcined Clay A and Clay B resulted in a considerable 28 day compressive strength improvement. The pozzolanic reactivity of Clay A and B is exp...

Lightweight aggregate concrete (LWAC) has been applied in marine structures in recent years due to its lower density compared to conventional concrete. The main durability issue is the corrosion of steel reinforcement induced by the chloride ion ingress and subsequent spalling due to volume expansion of steel rust. Besides, a damaged surface is pro...

The effect of a softwood calcium lignosulfonate, LSs, on the ettringite formed in cement paste was investigated. Two Portland cements, mainly differing in surface area and C 3 A content, were used. The effect of LSs addition time was studied, by adding either the LSs immediately with the mixing water or after 10 min of hydration. After 30 min of hy...

Fly ash is an industrial by-product deriving from electricity generating plants. It is the by-product of burning coal or lignite. Fly ash is one of the first artificial admixtures used for the production of concrete since the first decades of the 20th century. Its chemical and mineralogical composition mainly depends on the relevant properties of t...

Several successful demonstration projects have been conducted the past 20 years in order to verify the practical, technical and environmental applicability of recycled aggregates. Furthermore, recycled aggregates are included for use in nearly all of the European (EN) aggregate standards, though at varying implementation level. A new Indo-Norwegian...

The effect of softwood calcium lignosulfonate, LSs, on the rheology and setting time of cement paste has been investigated. Two Portland cements with different surface area and C3A content were used. The lignosulfonate was added either immediately with the mixing water or delayed after 10 min of hydration. The cement pastes were characterized in te...

The aim of this paper is to assess the mechanisms of consumption of softwood calcium lignosulfonate (LSs) by cement paste. The LSs consumption by two different cements (CX and ANL) and two reference materials (CaCO3 and Ca(OH)2) was investigated, either by adding the LSs immediately with the mixing water (IA) or after 10 min of hydration (DA). For...

A new concept is described for low pH concrete that can allow reinforcement with aluminium metal rods or fibres. In regular concrete the high pH will after short while lead to substantial amounts of hydrogen gas evolution. However, by replacing cement partially by an active pozzolan (e.g. calcined blue clay) in a sufficient amount to consume all ca...

In 1983, samples of reinforced concrete made from a range of concrete mixtures containing varying amounts of CEM I and silica fume were placed in a marine tidal zone at Trondheim, Norway. Examination and testing of the samples occurred periodically during the initial 21.5 years of exposure. In 2014, after 31 years exposure, the field site closed an...

Great attention is currently paid to the use of structural lightweight aggregate concrete (SLWAC) in marine structures, floating structures in particular, due to its lower density, but also potentially improved durability compared to conventional concrete. However, extra care has to be taken in structural design because of its brittleness, and in p...

Lignosulfonate plasticizers are sustainable bio-admixture for concrete and originate from two essential different tree types; hardwood and softwood. The influence of these different lignosulfonates on the rheology and setting time of cement paste with w/c =0.40 was studied. Four different cements were made by adding 3% gypsum to 4 clinkers with a w...

The dispersing effectiveness of five commercial plasticizers; lignosulfonate (LS), naphthalene sulphonate-formaldehyde polycondensate (NSF) and three polycarboxylate ethers (PCEs) were quantitatively investigated in blended cements where ordinary portland cement (OPC) was partly replaced by fly ash (FA) up to 60%. The capacity of the plasticizers i...

For marine reinforced concrete (RC) structures, chloride initiated corrosion of reinforcement is generally accepted as the service life limiting degradation mechanism. A methodology is described for how the maximum required chloride diffusion coefficient (D) of a concrete for achieving an intended service life (t) can simply be calculated as a func...

Due to their silica content, most light weight aggregates (LWAs) are potentially reactive. Despite this, knowledge regarding pre-testing ASR properties of LWA and LWA concrete (LWAC) is lacking internationally. The accelerated mortar prism test shows that several LWAs can develop ASR, but it is uncertain if this will ever occur in the field. As a p...

The applicability of a combination of sodium thiocyanate (NaSCN), diethanolamine (DEA) and glycerol (Gly) with small dosages as a ternary hardening accelerating admixture for fly ash blended cement (OPC-FA) was studied. The ternary admixture induced higher early and later age mortar strength at both low (5 °C) and normal (20 °C) temperature. Despit...

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 were obser...

The effect of softwood based calcium- and sodium lignosulfonates on the early hydration of pastes of cubic and orthorhombic C3A with gypsum was investigated using isothermal calorimetry, XRD analysis and thermogravimetry. For XRD paste hydration was stopped with liquid nitrogen and isopropanol after 5, 15, 30 min and 1, 2, 5 h. Additional experimen...

The influence of supplementary cementing materials (SCMs) on the hydration and durability of blended cement has been evaluated using chemical and physical principles. Similarities and differences between various SCMs has been considered while they have been grouped into categories as latent hydraulic or pozzolanic and sub-divided into siliceous, al...

The utilization of man-made ashes in cement and concrete technological applications are reviewed and specific examples are given. In the case of coal ash with well-known fly ash as mature technology, examples are given on the reactivity of bottom ash as well. The possibilities and limitations of utilizing municipal solid waste incinerator (MSWI) as...

Calcareous clay rich in smectite was calcined at temperatures of 600-1000 °C using a pilot- and industrial scale rotary kiln. Compressive strength of mortars was tested between 1-365 days, when 20-65 % of OPC was replaced by calcined clay at equal w/c-ratios. With respect to reactivity as a pozzolan, the optimum calcination temperature was around 8...

Alternative binders are in this study defined as binders without Portland cement. In this particular project it will be based on calcined clay or fly ash as a source of reactive silica and alumina in combination with lime and calcium sulphate (e.g. gypsum) and/or calcium carbonate to stabilize special calcium aluminate phases like ettringite and/or...

The reactivity and microstructure of cement paste and mortar where cement is replaced by up to 65 vol% calcined marl are discussed. It was found that the compressive strength evolution of mortar is following the same linear relation with amount of hydrate water at early ages for different cement replacements (35-65 vol%), but that this deviates and...

The dispersing effectiveness of five commercial plasticizers; lignosulfonate (LS), naphthalene sulphonate–formaldehyde polycondensate (NSF) and three polycarboxylate ethers (PCEs) were quantitatively investigated in blended cements where ordinary portland cement (OPC) was partly replaced by calcined marl (CM) up to 60%. CM drastically viscosified a...

The influence of two Ca-lignosulfonates (LS), one softwood (LSs) and one hardwood (LSh) based, on the phase changes during the early hydration of ordinary Portland cements was investigated using isothermal calorimetry, in-situ XRD, and thermal analysis. In the presence of LS the hydration of C3S and C3A was retarded. LS was found to influence the s...

Production of cement is ranking 3rd in causes of man-made carbon dioxide emissions world-wide. Thus, in order to make concrete more sustainable one may work along one or more of the following routes; 1) Replacing cement in concrete with larger amounts of supplementary cementing materials (SCMs) than usual, 2) Replacing cement in concrete with combi...

Well hydrated cement paste was exposed to MgCl2, CaCl2 and NaCl solutions at 20 °C. The chloride binding isotherms for free chloride concentrations ranging up to 1.5 mol/l were determined experimentally. More chlorides were found to be bound when the associated cation was Mg2 + or Ca2 + compared to Na+. The chloride binding capacity of the paste ap...

When concrete is exposed to sea water, it has been observed that the composition of the outer most millimeters of the concrete is considerably altered compared to the composition of the bulk concrete. The limited size of this zone complicates the investigation of the phases formed. This paper presents a new experimental set-up in which hydrated cem...

In an attempt to improve the properties, lightweight aggregates were produced from clay with the addition of Na2CO3, SiO2, Fe2O3, and Fe in quantities between 2 and 10 wt% and examined with respect to strength, density and expansion behavior. The additives were mixed into dry clay powder, water was added and pellets were formed by hand and fired at...

The effect of softwood (LSs) and hardwood (LSh) based lignosulfonates on the early hydration of Portland cement paste was studied using in-situ XRD, isothermal calorimetry, and thermal analysis. The calorimetric measurements showed that the main hydration peak is retarded adding increasing amount of the investigated LS. There was no major differenc...

The effect of two lignosulfonates, one softwood (LSs)- and one hardwood based (LSh), on the early hydration of three Portland cements was studied with isothermal calorimetry and in-situ XRD. In-situ XRD proved to be a good method for detecting the influence of LS on the evolution of single phases during the hydration of cement. In the presence of l...

Calcium sulfate is the common set regulator in Portland cement. It is shown that ground clinker can be set regulated by other soluble calcium salts than gypsum. Rheology of paste is improved when gypsum is replaced by the other salts, due to less hydration and less crystals of acicular shape. For in particular calcium nitrate the cumulative hydrati...

Four different cements made from gypsum mixed with clinkers possessing varying amounts of clinker phases were employed to investigate the influence of lignosulfonate on the early age rheological and hydration properties of cement pastes. Two test methods were employed; the parallel plate rheometry and isothermal calorimetry. Here, lignosulfonate wa...

Lightweight aggregates (LWAs) were successfully produced both in a pilot-scale rotary kiln and in a laboratory chamber furnace. The mechanical properties of LWA were investigated in detail applying the European standard crushing resistance test (CR-test) as well as the single pellet compression test (spc-test). The spc-test showed that LWA pellets...

Whether or not concrete prism tests developed for assessment of alkali-silica reactivity of aggregates might be suitable for general ASR performance testing of concrete has been evaluated. This paper discusses how variations in specimen pre-treatment, ASR exposure conditions and prism size influence the rate and amount of alkali leaching and prism...

Whether or not concrete prism tests (CPTs) developed for assessment of alkali silica reactivity of aggregates might be suitable for general ASR performance testing of concrete has been evaluated. This paper presents the background for the choice of test procedures and results on how variations in specimen pre-treatment, ASR exposure conditions and...