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1.	Abbasiverki, Roghayeh, et al. (författare) Analysis of shallowly buried reinforced concrete pipelines subjected to earthquake loads 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; :51, s. 111-130 Tidskriftsartikel (refereegranskat)abstract Buried reinforced concrete pipelines are widelyused in e.g. water and wastewater systems. Failure of these infrastructures mayresult in drastic effects and recently they have been brought into focus asvital components in safety systems for nuclear power installations. The highlevel of safety has here lead to a demand for reliable earthquake risk analyses.In this paper, methods are compared and the use of seismic design loadsdemonstrated. FE analysis in 2D of soil-pipe interaction under seismic wavepropagation is performed. The performance of concrete pipes subjected toseismic waves with different frequency content is evaluated with respect todifferent soil condition but also water mass effect.
2.	Ahmed, Lamis, et al. (författare) Dynamic Measurements for Determining Poisson’s Ratio of Young Concrete 2018 Ingår i: Nordic Concrete Research. - 0800-6377. ; :58, s. 95-105 Tidskriftsartikel (refereegranskat)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.
3.	Ahmed, Lamis, et al. (författare) Finite element simulation of shotcrete exposed to underground explosions 2012 Ingår i: Nordic Concrete Research. - : Nordic Concrete Federation. - 0800-6377. ; :45, s. 59-74 Tidskriftsartikel (refereegranskat)abstract An elastic finite element model is used tosimulate theinducedstress waves from blasting, propagating in rock towards shotcrete on a tunnel wall. Due to the inhomogeneous nature of the rock, the stress wavesattenuate onitsway from the point of explosiontowardsthe shotcrete on the rock surface. Material damping for the rock-mass is estimated from in-situ measurements. The vibration resistance of the shotcrete-rock support system depends on the material properties of the shotcrete. Age-dependent material properties are varied to investigate the behaviour of young shotcrete subjected to blast loading. Finally, finite element analysis results are presented and verified through comparison with other numerical models, measurements and observations.
4.	Al-Gburi, Majid, et al. (författare) Effect of the boundary conditions on the crack distribution in early age concrete 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 50, s. 347-351 Tidskriftsartikel (refereegranskat)abstract Restrained movement in early age concrete may cause cracking. The boundary conditions – restraint – influence the possible crack distribution. This study aims at highlighting the effect of such restraint on the crack distribution. This is done by using the “Cracking Model for Concrete” in ABAQUS/Explicit simulating the non-linear behaviour under and after cracking. In the study the typical case wall-on-slab was in focus using a structure previously been tested in laboratory with both fixed and free bottom slab. The result of the modelling shows fairly good agreement with the cracks observed in the tests.
5.	Al-Gburi, Majid, et al. (författare) Reducing Thermal Crack Risks Caused by Restraint in Young Concrete - A Case Study on Walls of Water Tanks 2022 Ingår i: Nordic Concrete Research. - : Walter de Gruyter. - 0800-6377 .- 2545-2819. ; 66:1, s. 41-54 Tidskriftsartikel (refereegranskat)abstract Concrete cracks in structures such as water tanks and nuclear power stations cause anxiety to owners, contractors and engineers. These cracks may significantly increase the structure’s permeability and thus increase leakage, reduce durability, and eventually lead to loss of structural functionality. Therefore it is important to minimize their occurrence and size. To identify effective ways of minimizing cracking in young concrete segments, a parametric study was conducted using the finite element method (FEM). Parameters considered include casting sequence, joint position, wall height, and cooling. The study examined continuous and jumped casting approaches to the casting of a cylindrical reinforced concrete tank for a sewage-treatment plant, with and without the application of the ‘kicker’ technique in which the lower part of the wall is cast with the slab. The main cause of cracking is thermal change and restraint imposed by adjacent older structures, and the FEM predictions agree well with experimental observations. Continuous casting is most effective at minimizing cracking because it creates only two contact edges between newly cast and existing structures producing the lowest level of restraint. The kicker technique is shown to be very effective for reducing restraint and consider rephasing.
6.	Al-Gburi, Majid, et al. (författare) Simplified methods for crack risk analyses of early age concrete : Part 2: Restraint factors for typical case wall-on-slab 2012 Ingår i: Nordic Concrete Research. - 0800-6377. ; 46:2, s. 39-56 Tidskriftsartikel (refereegranskat)abstract Existing restraint curves have been applied to the method of artificial neural networks (ANN) to model restraint in the wall for the typical structure wall-on-slab. It has been proven that ANN is capable of modeling the restraint with good accuracy. The usage of the neural network has been demonstrated to give a clear picture of the relative importance of the input parameters. Further, it is shown that the results from the neural network can be represented by a series of basic weight and response functions. Thus, the results can easily be made available to any engineer without use of complicated software.
7.	Al-Gburi, Majid, et al. (författare) Simplified methods for crack risk analyses of early age concrete : Part 1: Development of Equivalent Restraint Method 2012 Ingår i: Nordic Concrete Research. - 0800-6377. ; 46:2, s. 17-38 Tidskriftsartikel (refereegranskat)abstract The present study deals with both the compensation plane method, CPM, and local restraint method, LRM, as alternative methods studying crack risks for early age concrete. It is shown that CPM can be used both for cooling and heating, but basic LRM cannot be applied to heating. This paper presents an improved equivalent restraint method, ERM, which easily can be applied both for usage of heating and cooling for general structures. Restraint curves are given for two different infrastructures, one founded on frictional materials and another on rock. Such curves might be directly applied in design using LRM and ERM.
8.	Anderberg, Anders, et al. (författare) Hydroxide ion concentration at an interface between concrete and a self-levelling flooring compound 2007 Ingår i: Nordic Concrete Research. - 0800-6377. ; 36, s. 37-47 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract This article presents results from measurements of hydroxide ion transport between a concrete and a floor screed of a lower alkalinity than the concrete. As many floor coverings and floor adhesives are sensitive to high alkaline conditions it is important to know how hydroxide ions are transported to be able to evaluate the long-term function of floor constructions. It was found that only minor transport of hydroxide ions occurs in the hygroscopic moisture range. One conclusion is therefore that a floor screed of lower alkalinity may protect sensitive floorings from the high alkalinity present in concrete.
9.	Anderberg, Anders, et al. (författare) Moisture in Self-levelling Flooring Compounds. Part I. Water Vapour Diffusion Coefficients 2004 Ingår i: Nordic Concrete Research. - 0800-6377. ; Publication 32:2/2004, s. 3-15 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Abstract in UndeterminedDiffusion coefficients of three self-levelling flooring compounds (SLC) and water vapour resistance of a primer have been measured with the cup method. The results show that the diffusion coefficient is dependent not only on the vapour content (relative humidity), but also on the absolute moisture content, i.e., there is a hysteresis effect on moisture transport. At RH lower than approximately 90 %, SLC have higher diffusion coefficients than a standard concrete (w/c 0.7 OPC), but the opposite is true at higher RH. This can be explained by the fact that SLC have different pore structure than concrete. The latter may also be an effect of the high amount of polymer in SLC that form a film throughout the material and thereby limits capillary moisture transport.
10.	Anderberg, Anders, et al. (författare) Moisture properties of self-levelling flooring compounds. Part II. Sorption isotherms. 2004 Ingår i: Nordic Concrete Research. - 0800-6377. ; Publication 32:2/2004, s. 16-30 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Moisture sorption in self-levelling flooring compounds was investigated by using a sorption balance. Results are presented as sorption isotherms. Influence of temperature, age, water to binder ratio and carbonation are also presented. An increased temperature and increased water to binder ratio gives lower moisture sorption. Results from scanning curves indicate that, when changing sorption mode, even a minute change in moisture content may result in a significant change in relative humidity in the material.
11.	Andersson, Louise, et al. (författare) Continuous Preventive Bridge Maintenance of Swedish Municipalities : A Survey on Common Practice 2018 Ingår i: Nordic Concrete Research. - Oslo : Walter de Gruyter GmbH. - 2545-2819 .- 0800-6377. ; 58 Tidskriftsartikel (refereegranskat)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).
12.	Andersson, Louise, et al. (författare) Effect of High-Pressure Washing on Chloride Ingress in Concrete : Development of an Accelerated Test Method 2022 Ingår i: Nordic Concrete Research. - : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 67:2, s. 35-50 Tidskriftsartikel (refereegranskat)abstract Bridges constitute an important part of the infrastructure. For bridges to have the longest possible service life with minimum repairs, the maintenance is of great importance. One type of bridge maintenance that is rarely researched is the continuous preventive maintenance. The continuous preventive maintenance consists of removal of vegetation, cleaning of bridge joints and drainage systems as well as high-pressure washing of the structure. The effect of washing is discussed but not properly researched. A study on the effectiveness of high-pressure washing on concrete is therefore being conducted. An accelerated test method is being developed to mimic field testing. The method has been developed through tests on small concrete specimens subjected to fluctuating temperature, fluctuating moisture, and repeatable exposure to de-icing salt during several cycles. The specimens are of two recipes where one represents an old concrete bridge with rather high water-cement ratio (0.6) and the other one represents a new concrete bridge with a low water-cement ratio (0.4). The first two versions of the method are described. The second version shows promising results, but the method needs further development to incorporate additional factors.
13.	Ansell, Anders, et al. (författare) Modelling of thermally induced cracking of a concrete buttress dam 2008 Ingår i: Nordic Concrete Research. - 0800-6377. ; 38, s. 69-88 Tidskriftsartikel (refereegranskat)abstract Some of the larger hydropower dams in Sweden are buttress dams, consisting of up to 100 concrete monoliths formed by a front plate with a supporting buttress. Cracks have been observed in some dams, through the buttresses and at the base close to the rock foundation. The combined effects of restrained thermal displacements and loads caused by water are studied through finite element analysis. The results demonstrate the use of a non-linear material model and show that it is possible to follow the formation and propagation of the cracks. The analyses indicate that thermal stresses in combination with the loads caused by external water pressure are the reason for the cracking.
14.	Baba Ahmadi, Arezou, 1985, et al. (författare) Utilization of Bio Ashes in Cement-based Materials: A Case Study in Cooperation with Pulp and Paper and Energy Production Industries in Sweden 2020 Ingår i: Nordic Concrete Research. - : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 63:2, s. 63-78 Tidskriftsartikel (refereegranskat)abstract Worldwide increased concern of the CO2 emissions has led to the replacement of coal by biomass in combustion-based power plants. However, this would cause the scarcity of fly ash, one of the most well-known rest products from coal combustion, which is used as supplementary cementitious materials (SCM) in construction sector to reduce the large environmental footprint of cement production. Seeking to find alternative SCMs, this article aims to demonstrate the viability of using bio ashes in Sweden as SCM, which, due to lack of studies validating their value, are landfilled today. According to the obtained results, bio ashes produced at pulp and paper industries have a considerably consistent chemical composition and exhibit a satisfactory pozzolanic behaviour. Nevertheless, according to the conclusions of this study, the pozzolanicity of these alternative binders is not reflected equally with respect to the most known reactivity tests for common SCMs. The results imply that although “R3” tests method infers the pozzolanic characteristics of the bio ashes in focus of this study, the “activity index test” as well as “calcium consumption test” indicate otherwise.
15.	Babaahmadi, Arezou, 1985, et al. (författare) Mineralogical, Physical and Chemical Characterization of Cementitious Materials Subjected to Accelerated Decalcification by an Electro-Chemical Method 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 1/2014:49, s. 181-198 Tidskriftsartikel (refereegranskat)abstract To facilitate the service life predictions regarding durability of nuclear waste repositories acceleration methods enhancing the decalcification process are needed. In this study an electro-chemical migration method to accelerate leaching of calcium from cementitious specimens of sizes 50×100Ø and 75×50Ø mm is presented. The mineralogical, physical and chemical properties of degraded samples are characterized. The results demonstrate that up to 70% decrease in strength, 50 % decrease in E-modulus, 90 % increase in gas permeability, at least 70% increase in chloride diffusion coefficient and 70 % increase in pore volume could be expected due to leaching of portlandite from concrete.
16.	Bagge, Niklas, et al. (författare) Full-Scale Test to Failure of a Prestressed Concrete Bridge in Kiruna 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 50, s. 83-86 Tidskriftsartikel (refereegranskat)abstract To calibrate methods for condition assessment of prestressed concrete (PC) bridges, tests areplanned for a 50 year old five-span bridge with a length of 121 m in Kiruna in northern Sweden.Both non-destructive and destructive full-scale tests will be performed. This paper summarisesthe test programme, which comprises evaluation of the structural behaviour of the bridge, theresidual forces in the prestressed steel, methods for strengthening using carbon fibre reinforcedpolymers (CFRP) and the shear resistance of the bridge slab.
17.	Bagge, Niklas, et al. (författare) Instrumentation and Full-Scale Test of a Post-Tensioned Concrete Bridge 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 51, s. 63-83 Tidskriftsartikel (refereegranskat)abstract To meet new demands, existing bridges might be in need for repair, upgrading or replacement. To assist such efforts a 55-year-old post-tensioned concrete bridge has been comprehensively tested to calibrate methods for assessing bridges more robustly. The programme included strengthening, with two systems based on carbon fibre reinforced polymers (CFRPs), failure loading of the bridge’s girders and slab, and determination of post-tension cables’ condition and the material behaviour. The complete test programme and related instrumentation are summarised, and some general results are presented. The measurements address several current uncertainties, thereby providing foundations for both assessing existing bridges’ condition more accurately and future research.
18.	Berrocal, Carlos Gil, 1986, et al. (författare) Corrosion-induced cracking and bond behaviour of corroding reinforcement bars in SFRC 2017 Ingår i: Nordic Concrete Research. - 0800-6377. - 9788282080569 ; , s. 123-126 Konferensbidrag (refereegranskat)abstract In this study, an experimental programme has been carried out to investigate the influence of fibres on the onset of corrosion-induced splitting cracks. Cylindrical lollipop specimens with a centrally positioned Ø16 mm bar and varying cover depths from 40 to 64 mm were subjected to accelerated corrosion. A constant current of 100 μA/cm2 was impressed through the specimens and the electrical resistance between each rebar and an external copper mesh acting as cathode was monitored. The fibres, due to their confining effect, contributed to delay crack initiation, improve the post-peak bond behaviour and retain the initial splitting strength for corrosion levels of up to 8%.
19.	Blanksvärd, Thomas, et al. (författare) Strengthening of concrete structures with cement based bonded composites 2008 Ingår i: Nordic Concrete Research. - 0800-6377. ; :2, s. 143-163 Tidskriftsartikel (refereegranskat)
20.	Boubitsas, Dimitrios (författare) Durability of concrete with mineral additions 2002 Ingår i: Proceedings / Nordic Concrete Research Meeting, Elsinore, Denmark, 2002. - 0800-6377. - 8291341567 ; , s. 6-8 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
21.	Boubitsas, Dimitrios (författare) Replacement of cement by limestone filler: The effect on strength and chloride migration in cement mortars 2004 Ingår i: Nordic Concrete Research. - 0800-6377. ; 32:2 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
22.	Boubitsas, Dimitrios (författare) Use of limestone in cement : The effect on strength and chloride transport in mortars 2013 Ingår i: Nordic Concrete Research. - 0800-6377. ; :47/1, s. 61-80 Tidskriftsartikel (refereegranskat)abstract This paper describes studies carried out to examine the influence_x000D_ on strength and chloride ingress when Portland cement is replaced_x000D_ with limestone filler. In the chloride ingress study both an_x000D_ accelerated method and field exposure measurements up to one_x000D_ year were employed. The results show that the method of_x000D_ measuring the resistance to chloride ingress can have a major_x000D_ influence on the assessment of the effect of different binders._x000D_ Further, the effect on chloride resistance, when replacing Portland_x000D_ cement with limestone filler is strongly dependent of the_x000D_ replacement ratio. The effect on compressive strength when_x000D_ replacing Portland cement with limestone filler is also strongly_x000D_ dependent of the replacement ratio.
23.	Bryne, Lars-Elof, et al. (författare) Laboratory testing of early age bond strength between concrete for shotcrete use and rock 2013 Ingår i: Nordic Concrete Research. - 0800-6377. ; 47, s. 81-100 Tidskriftsartikel (refereegranskat)abstract Shotcrete(sprayed concrete) is, together with rock bolts, the most important material used for reinforcement in hard rock tunnelling. Sprayed concrete differs from ordinary concrete through the application technique and the addition of accelerators which give immediate stiffening. The bond between sprayed concrete and rock is one of the most important properties in the quality assessment of shotcreted concrete. During the very early age after spraying the physical properties of the concrete and the bond to the rockdepend on the accelerator and the micro structure that is formed. In this work a laboratory test method for measuring early bond strength for very young shotcrete is presented.
24.	Carlswärd, Jonas, et al. (författare) Avoiding undesirable end results of bonded steel fibre concrete overlays : observations from tests and theoretical calculations 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 49, s. 93-112 Tidskriftsartikel (refereegranskat)abstract Due to a high degree of damages and undesirable final results of bonded overlays, research has been conducted to develop recommendations on design and execution. Laboratory and half scale tests as well as theoretical analyses have been carried out including e. g. base and end restraint tests on overlays with various reinforcement, concrete qualities, substrate preparing and curing. Also, analytical and numerical calculations have been performed. Results reveal that the bond between overlay and substrate is the most critical parameter for a successful final result. Other key parameters are shrinkage and curing, while fibre and bar reinforcement generally proved to be less significant. Theoretical models work well on this case and will be further developed
25.	Carlswärd, Jonas, et al. (författare) Shrinkage cracking of thin concrete overlays 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 50, s. 355-359 Tidskriftsartikel (refereegranskat)abstract Due to a high degree of damages and undesirable end results of bonded overlays, research is conducted to develop recommendations on design and execution. Laboratory and full scale tests as well as theoretical analyses have been carried out including e. g. base and end restraint tests on overlays with various reinforcement, concrete qualities, substrate preparing and curing. Moreover, analytical and numerical calculations have been performed. Results reveal that the e. g. bond between overlay and substrate is a critical parameter for a successful end result. Another key parameter is sufficient curing, while reinforcement generally proved to be less significant. Theoretical models works well on this structural situation and will be further developed.
26.	Cyron, Wojciech, et al. (författare) Bonded Concrete Overlays: A Brief Discussion on Restrained Shrinkage Deformations and Their Prediction Models 2019 Ingår i: Nordic Concrete Research. - : Walter de Gruyter. - 0800-6377 .- 2545-2819. ; 61:2, s. 107-129 Tidskriftsartikel (refereegranskat)abstract Bonded concrete overlays (BCO) on bridge decks are beneficial solutions due to their superior properties as compared to the typical asphalt pavement. A significant number of overlays suffer however, from occurrence of cracks and delamination due to poor bond, and restrained shrinkage and thermal dilation. Over the past years different appraisals for estimation of the restrained deformations have been developed, from micro-scale models, based on poromechanics, to empirical equations as given in B3 or B4 models suggested by Baiant. This paper provides a short overview of calculation models along with a brief theoretical explanation of shrinkage mechanism.
27.	Dias Ferreira Da Silva, Nelson, 1978, et al. (författare) Critical Conditions for Depassivation of Steel in Concrete: Interface Chloride Profiles and Steel Surface Condition 2012 Ingår i: Nordic Concrete Research. - 0800-6377. ; 45, s. 111-123 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract The composition and macrostructure of the concrete-steel interface and the surface finish of the steel are fundamental for the chloride induced corrosion initiation in reinforced concrete, with direct influence in the chloride threshold values (Cth). In this paper these characteristics were examined for vertically cast samples immersed in salt solution. After depassivation, the specimens were open for visual examination. Corrosion always initiated at the front side and surface defects were found to influence the corrosion onset. Chloride, calcium and iron profiles along the interface were drawn by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and higher chloride contents were measured around active corroding areas.
28.	During, Otto, et al. (författare) Rice Husk Resource for Energy and Cementitious Products with Low CO2 contributions 2018 Ingår i: Nordic Concrete Research. - : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 59:2, s. 45-58 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Rice Husk Ash (RHA) is a well-known supplementary cementitious materials (SCMs) that can be used for concrete with reduced CO2 contributions. In 2016, only Nepal produced 5.2 million tonnes rice that gave about 1.14 million tonnes rice husk. The rice husk can also be used directly in a cement kiln as a fuel. This study analysis the potential CO2 reductions from three scenarios and emphasis strengths, weaknesses, opportunities and treats in the production systems for initiate a decision process with possibilities to get an industry project financed from the green climate found. The highest CO2 benefits were from rice husk used in a cement kiln were half of the yearly rice husk production in Nepal could reduce the climate impact with 808000 tonnes CO2.
29.	Döse, Magnus, et al. (författare) Effect on Radon Exhalation Rate Due to Cracks in Concrete 2019 Ingår i: Nordic Concrete Research. - : NORDIC CONCRETE FEDERAT. - 0800-6377 .- 2545-2819. ; 61:2, s. 79-90 Tidskriftsartikel (refereegranskat)abstract The second largest cause of lung cancer in the World is related to radon (Rn-222) and its progenies in our environment. Building materials, such as concrete, contribute to the production of radon gas through the natural decay of U-238 from its constituents. The Swedish Cement and Concrete Research Institute (CBI), part of RISE (Research Institute of Sweden AB), has examined the effects of cracks in concrete on two different concrete recipes where an Ordinary Portland Cement, OPC-CEM-I concrete (REF) and an OPC concrete including a hydrophobic additive (ADD) were addressed. Two concrete prisms from each concrete recipe were examined. The radon exhalation rate was measured in the pristine state and after concrete cracks had been induced into the concrete prisms. Measurements were performed with an ATMOS 33 ionizing pulsation chamber. The results indicate a strong influence of cracks on the radon exhalation rate. An increase in radon exhalation rate was calculated for every test prism. The increase in radon exhalation rate varied between 80 and 260 %. The crack apertures may play a significant role on the exhalation rate. The concrete prisms with the largest apertures (ADD) also generated the highest radon exhalation rates. The results imply that there could be a substantial variation in the exhalation rate, due to numerous factors, but nonetheless, the results should, raise the awareness of the impact cracks in concrete structures, may have on the final exhalation rate of radon. The exhalation rate of the recipe with an additive (ADD) also showed a lower exhalation rate than for the reference recipe (REF), when compared in a pristine state. This was in part expected. However, the effect of induced cracks and its aperture, seemingly trumps the effect that an additive may play on the radon exhalation rate, when cracks are induced.The hypothesis is in part verified in view of the results of the prism for the ordinary Portland recipe (REF-prisms), were an increase of approximately 100 % would be expected due to the total surface increase. The results also indicate this. The major increase in the radon exhalation rate of the ordinary Portland recipe including an additive, implies however other factors, such as minor internal cracks, that may substantially contribute to the final exhalation rate.
30.	Döse, Magnus, 1970-, et al. (författare) Reduction of Radon Gas in Concrete Using Admixtures and Additives 2018 Ingår i: Nordic Concrete Research. - Oslo. - 0800-6377. ; 58 Tidskriftsartikel (refereegranskat)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.
31.	Edrees, Tarek, et al. (författare) Semi-active structural control strategies 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 50, s. 31-34 Tidskriftsartikel (refereegranskat)abstract The utilization of structural control systems to alleviate the responses of civil engineering structures, under the effects of dynamics loadings, has become a standard technology, while still there are numerous of current research approaches for advancing the effectiveness of these methodologies. It is important for successful application of smart structure to provide an effective control algorithm to compute the control forces to be applied on the building in order to reduce the external disturbances. The aim of this article is to provide a review of the control strategies to control the performance of semi-active systems utilized in civil engineering structures.
32.	Ekström, Daniel P T, 1976, et al. (författare) Industrial bridge building- An effective bridge construction process through an integrated design and construction process 2014 Ingår i: Nordic Concrete Research. - 0800-6377. - 9788282080439 ; 2014:2, s. 79-82 Konferensbidrag (refereegranskat)abstract This PhD-project aims to develop and industrialise bridge building, in order to achieve a more efficient and sustainable bridge construction process. The advancements of several key areas - materials science and technology, design and analysis methods, production techniques and information and communication technology - have resulted in a vast potential to rationalise the process and renew the designer's role. Initially, the project will define effective bridge construction criteria’s by means of interviews and case-studies. The work should result in an integrated design and production process. This project is a collaborative project, involving: Swedish Transport Administration, WSP and Chalmers.
33.	Emborg, Mats, et al. (författare) Fatigue strength of cable couplers in prestressed concrete beams 1982 Ingår i: Nordic Concrete Research. - 0800-6377. ; 1, s. 5.1-5.14 Tidskriftsartikel (refereegranskat)abstract Fatigue tests have been carried out on ten prestressed concrete beams. Six of the beams were furnished with a cable coupler in the mid-span and four beams had no cable coupler. The uncoupled beams could in some cases sustain 9 times as many load cycles as the coupled beams. Some probable causes to the coupled beams lower fatigue strength are discussed in the paper.
34.	Emborg, Mats, et al. (författare) Industrial concrete construction for a better economy and working environment : possibilities and obstacles with self compacting concrete 2008 Ingår i: Nordic Concrete Research. - 0800-6377. ; :2, s. 47-59 Tidskriftsartikel (refereegranskat)abstract The implementation of SCC together with new reinforcement and form techniques make it possible to increase the degree of industrialisation. It has been found in research at LTU that detailed planning and optimization of the building process, are essential utensils to successfully introduce such new techniques. However, also important is to address the technical issues hindering the marketing of SCC. Such issues are the robustness of the concrete and he surface quality. Thus, a discussion is given in the article on the optimization of robust SCC mixes and test results both from laboratory and building site as well as how criteria of SCC can be defined.
35.	Emborg, Mats, et al. (författare) Temperature stresses in early age concrete due to hydration 1984 Ingår i: Nordic Concrete Research. - 0800-6377. ; :3, s. 28-48 Tidskriftsartikel (refereegranskat)abstract Theoretical models for the analysis of thermal induced stresses in massive concrete structures are presented. Laboratory tests are conducted in order to calibrate the theoretical models for different types of cement, concrete mixtures etc
36.	Enckell, Merit (författare) New Årsta Railway Bridge : A case study on the long-term Structural Health Monitoring with Fibre Optic Sensors 2011 Ingår i: Nordic Concrete Research. - 0800-6377. ; :2/2011, s. 123-142 Tidskriftsartikel (refereegranskat)abstract The New Årsta Railway Bridge was built in 2000-2005. The structure is a unique pre-stressed concrete girder bridge with slender and optimised design. Structural Health Monitoring System was installed on the bridge during construction. One characteristic span is mainly instrumented with several sensors and monitoring is still ongoing.This paper presents the Fibre Optic Sensor system including thermocouples; and their function. Observations, malfunctions and inconvenience during construction, testing and operation are collected, carefully documented and analysed. Strain and temperature data are collected from first casting up to date.Results are highlighted and conclusions are drawn. Recommendations are given, based on the experience gained so far. Furthermore, general, accumulated knowledge about monitoring is given.
37.	Fagerlund, Göran, et al. (författare) Frost resistance of high performance concrete 1996 Ingår i: Nordic Concrete Research. - 0800-6377. ; , s. 48-49 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
38.	Fahimi, Shayan, et al. (författare) Replication of Crack Pattern in FE Analysis Based on Discretization of Tension Softening Curves 2017 Ingår i: Nordic Concrete Research. - 0800-6377. ; 56:1, s. 1-9 Tidskriftsartikel (refereegranskat)abstract Today, there is an increasing need for reliable methods for condition assessment and service-life evaluation of existing structures. Although advanced 3D Nonlinear Finite Element (3D NLFE) analysis has proven to be capable of describing the behavior of reinforced concrete in a comprehensive way, the analysis results are difficult to couple with visual inspection data such as cracking and spalling. Moreover, 3D NLFE programs are numerically expensive and incomprehensible for full-scale practical applications. Thus, the present study aims to couple 3D NLFE analysis with condition assessment data, and consequently to increase the accuracy, to optimize the computation time and to improve robustness of such analyses.
39.	Fall, David, 1983, et al. (författare) Reinforcement in tailor-made concrete structures 2011 Ingår i: Nordic Concrete Research. - 0800-6377. - 9788282080255 ; , s. 175-178 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
40.	Fjellström, Peter, et al. (författare) Heat loss compensation for semi-adiabatic calorimetric tests 2013 Ingår i: Nordic Concrete Research. - 0800-6377. ; 47:1, s. 39-60 Tidskriftsartikel (refereegranskat)abstract Heat of hydration has long been of importance since it affects the temperature levels within a concrete structure, and thus, potentially affects its durability. The only source of energy is the reaction between cement and water. This energy warms up the concrete sample and all the ambient materials. Therefore, in order to model these energies, the TSA (traditional semi-adiabat) setup is transformed into an associated sphere. By this, the temperature distribution and the energies within each layer of the TSA can be calculated. The sum of all energies gives the total heat of hydration. A refined model using a correction factor is introduced, which accounts for energies lost to the TSA setup materials. Results show that the effect of this factor cannot be disregarded, especially not for TSAs with low cooling factors.
41.	Fjellström, Peter, et al. (författare) Model for concrete strength development including strength reduction at elevated temperatures 2012 Ingår i: Nordic Concrete Research. - 0800-6377. ; 45:1, s. 25-44 Tidskriftsartikel (refereegranskat)abstract When casting concrete structures, one of the most important properties is the concrete strength development. The need of actions on site is different at various stages of hardening, from the fresh concrete to the hardened concrete. The paper defines a model analysing maturity and associated strength growth within three important time periods. The model can be applied separately within each of these periods depending on test data available.It is shown in the paper that the temperature plays an important role on the strength development of concrete structures. The hydration rate increases with increased temperatures, which can be described by maturity functions. If the concrete temperature remains high, strength reduction at later ages usually occurs compared to hardening at lower temperature, which may be denoted strength reduction at elevated temperatures or cross over effects. Both these phenomena have been implemented in the model for strength growth presented in the paper. The functionality of the model is demonstrated by evaluation of laboratory tests for five concrete mixes and two types of cement.
42.	Flansbjer, Mathias, et al. (författare) Meso Mechanical Study of Cracking Process in Concrete Subjected toTensile Loading 2018 Ingår i: Nordic Concrete Research. - Oslo : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 59:2, s. 13-29 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract This project focused on how the cracking process in concrete is influenced by both the micro and meso structures of concrete. The aim was to increase knowledge pertaining to the effect of critical parameters on the cracking process and how this is related to the material's macroscopic properties. A methodology based on the combination of different experimental methods and measuring techniques at different scales was developed. Crack propagation during tensile loading of small-scale specimens in a tensile stage was monitored by means of Digital Image Correlation (DIC) and Acoustic Emission (AE). After testing, crack patterns were studied using fluorescence microscopy.
43.	Fridh, Katja, et al. (författare) A model to calculate the CO2-uptake in a country’s concrete structures during service life and after 2014 Ingår i: Nordic Concrete Research. - 0800-6377. ; 50:2, s. 443-446 Tidskriftsartikel (refereegranskat)abstract During the project ‘The CO2-cycle in cement and concrete’ an analytical model to quantify the CO2-uptake in a country a specified year was developed. That was accomplished by deriving a new model for the carbonation process and as input to that, measurements of carbonation in concrete indoors and studies of carbonation in crushed concrete were made. Through knowledge of the cement production each year, the distribution of the cement into different products and estimations of what concrete quality each product has, the total uptake for Sweden was calculated. For the year 2011 was the CO2-uptake calculated to 300 000 tons.
44.	Fridh, Katja (författare) Dilation Measurements in a Low-temperature Calorimeter 1999 Ingår i: Nordic Concrete Research Meeting. - 0800-6377. ; , s. 304-306 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
45.	Fridh, Katja (författare) Frost resistance of high-performance concrete after six years of water storage 2002 Ingår i: Proceedings / Nordic Concrete Research Meeting, Elsinore, Denmark, 2002. - 0800-6377. - 8291341567 ; , s. 251-253 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
46.	Fridh, Katja, et al. (författare) The Internal Frost Resistance of High Performance Concrete 1999 Ingår i: Nordic Concrete Research Meeting. - 0800-6377. ; , s. 294-296 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
47.	Geiker, Mette Rica, et al. (författare) Screening of Low Clinker Binders, Compressive Strength and Chloride Ingress 2017 Ingår i: Nordic Concrete Research. - : Nordic Concrete Federation. - 0800-6377 .- 2545-2819. ; 57:2, s. 23-38 Tidskriftsartikel (refereegranskat)abstract This paper reports an initial screening of potential new binders for concrete with reduced CO2-emission. Mortars cured saturated for 90 days are compared with regard to a) compressive strength of mortars with similar water-to-binder ratio, and b) chloride ingress in similar design strength mortars exposed to seawater. The reference used was a binder composition typical for a Danish ready mixed concrete for aggressive environments and strength class C35/45. Based on the present investigation and assumptions up to around 15% reduction in CO2 emission from binder production might be obtained without compromising the 90 days compressive strength and resistance to chloride ingress in marine exposure by using selected alternative binders.
48.	Ghasemi, Yahya, et al. (författare) Particle Packing for Concrete Mix Design : Models vs. Reality 2014 Ingår i: Nordic Concrete Research. - Oslo : Nordic Concrete Federation. - 0800-6377. ; 51, s. 85-94 Tidskriftsartikel (refereegranskat)abstract The packing density of aggregates is of great importance in concrete mix design as obtaining a higher packing density leads to less usage of cement paste which has technical, environmental and economic benefits. It is thus of interest to model particle packing correctly. Hence, in this study, packing densities of seven mixes of aggregate were attained in the laboratory using the loose packing method and were compared to values suggested by three models: 4C, Compressible Packing Model and Modified Toufar Model. Modified Toufar showed 1.72% mean difference from the laboratory values while CPM and 4C had mean differences of 1.79% and 1.84% respectively. In addition, it was found that some of the models are preferable in certain mixtures.
49.	Ghasemi, Yahya, 1982-, et al. (författare) Particle packing of aggregates for concrete mix design : Models and methods 2014 Ingår i: Nordic Concrete Research. - Oslo : Nordic Concrete Federation. - 0800-6377. ; :50, s. 109-112 Tidskriftsartikel (refereegranskat)abstract An optimized aggregate particle packing density used as a base for concrete mix design provides economic, environmental and technical advantages. The particle packing density can be determined by many methods and predicted by different models. This paper reviews common packing and procedures and compares predictions of three common packing models to each other. It was found that the models tend to show different packing densities and percentage of ingredients for the same mixture. A test setup is proposed to determine the accuracy of each model’s prediction
50.	Gram, Annika, et al. (författare) Applications for Numerical Simulation of Self-Compacting Concrete 2010 Ingår i: Nordic Concrete Research. - 0800-6377. ; :2/2010, s. 143-154 Tidskriftsartikel (refereegranskat)abstract This paper, presenting practical applications for numerical simulation, is divided into two parts: 1. Verification and application of the numerical concrete model presented here and 2. Introduction of an on-site rheology assessment tool, the Rheo-Box, which is to be used for the concrete acceptance test in order to verify rheological parameters of the concrete as feedback to obtain satisfactory form filling. It is shown that simulated values correspond well to both analytical and experimental results for concrete flow. In the future, numerical simulation will be a more common tool for predictions of possibly complicated SCC castings.

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