| 1. |
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| 2. |
- Lindqvist, Jan Erik, et al.
(författare)
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Analysis of irradiated concrete : Microscopic and mechanical tests on concrete from a nuclear power plant containment structure
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Drilled concrete cores from the centralpart of the containment structure of reactor 2 in Oskarshamn weretested in the present study. Optical microscopy and scanning electron microscopy wereapplied.The microscopy analyses performed have not documented any changes in the properties of the concrete that can be interpreted as beingdue to the specific environment to which the samples havebeen exposed. The parameters that havebeen studied includecrack patterns that could indicate volume changes inthe aggregate or cement pasteand indications of alkali silica reaction. The observed differences in the concrete surface compared to the inner part of the concrete are such that they couldoccur in concrete exposed to a normal indoor environment. There are no crack patterns to indicatethat the radiation has caused a volume increase inthe aggregate or drying shrinkage in the cement paste. Thereareno changesin the crack patterns, porosity or polarization properties that may indicate reduced mechanical strength. The damage seen in the surface of sample 5 is likely to have beencaused by a local mechanical impact and thisdamage is superficial andlocal. The mechanical properties of the concrete were evaluated by uniaxial compression tests on cylinders machined from drilled cores. Full-field strain measurement was performed on the surface of the cylinders during the compression test. Optical full-field deformation measurement was conducted usinga measurement technique based on Digital Image Correlation (DIC) with a stereoscopic camera set-up, consisting of two CCDcameras. The basic idea behind DIC is to measure the deformation of the specimen duringtesting by tracking the deformation of a surface speckle pattern in a series of digital images acquired during loading. That there is some variation in strain between the various segments is natural, since the local stiffness depends on aggregate sizeand location. The general picture is that the strain distribution is relatively uniform along the length of the cylinder,which indicates that the tested cylinders do not exhibit any degradation of mechanical properties. There is also no significant difference between the cylinders taken towards the insideof the structure, compared with thosetaken towards the outside.The overall conclusion is that the tests carried out do not indicate any degradation of the mechanical properties, and that the properties in general are equivalent for the cores taken towards the inside and the outside of the structure.
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| 3. |
- Liu, Hongyuan, et al.
(författare)
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Characterisation of rock aggregate breakage properties using realistic texture-based modelling
- 2012
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Ingår i: International Journal for Numerical and Analytical Methods in Geomechanics. - : Wiley. - 0363-9061 .- 1096-9853. ; 36:10, s. 1280-1302
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Tidskriftsartikel (refereegranskat)abstract
- Realistic texture-based modelling methods, that is microstructural modelling and micromechanical modelling, are developed to simulate the rock aggregate breakage properties on the basis of the rock actual microstructure obtained using microscopic observations and image analysis. The breakage properties of three types of rocks, that is Avja, LEP and Vandle taken from three quarries in Sweden, in single aggregate breakage tests and in inter-aggregate breakage tests are then modelled using the proposed methods. The microstructural modelling directly integrates the microscopic observation, image analysis and numerical simulation together and provides a valuable tool to investigate the mechanical properties of rock aggregates on the basis of their microstructure properties. The micromechanical modelling takes the most important microstructure properties of rock aggregates into consideration and can model the major mechanical properties. Throughout this study, it is concluded that in general, the microstructure properties of rock aggregate work together to affect their mechanical properties, and it is difficult to correlate a single microstructure property with the mechanical properties of rock aggregates. In particular, for the three types of rock Avja, LEP and Vandle in this study, crack size distribution, grain size and grain perimeter (i.e. grain shape and spatial arrangement) show good correlations with the mechanical properties. The crack length and the grain size negatively affect the mechanical properties of Avja, LEP and Vandle, but the perimeter positively influences the mechanical properties. Besides, the modelled rock aggregate breakage properties in both single aggregate and inter-aggregate tests reveal that the aggregate microstructure, aggregate shape and loading conditions influence the breakage process of rock aggregate in service. For the rock aggregate with the same microstructure, the quadratic shape and good packing dramatically improve its mechanical properties. During services, the aggregate is easiest to be fragmented under point-to-point loading condition, and then in the sequence of multiple-point, point-to-plane and plane-to-plane loading conditions.
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| 4. |
- Liu, Hongyuan, et al.
(författare)
-
Microscope rock texture characterization and simulation of rock aggregate properties
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The literature review on the relationship between the textural properties and mechanical properties of rock aggregates indicates that most studies investigated the relationship in two separate processes, i.e. microscope observations and mechanical tests, and then correlate the mechanical properties with one of textural properties indirectly using various regression models.Samples of three granites with similar mineral content but varying mechanical properties are investigated by microscope texture quantification including image analysis followed by rock mechanics testing and rock aggregate testing in the laboratory. Computer simulation of rock mechanics properties, of strength of single aggregate particles and fracture of multiple particles in a cylindrical chamber (DSC test) is then made. Finally computer simulations are compared of with tumbling mill tests (LA test) through results from previous research.This study uses numerical modelling as a main tool to directly investigate the relationships, i.e. from the physical mechanisms' point of view and taking major textural properties into consideration. Two main modelling methods, i.e. microstructural modelling and micromechanical modelling are implemented. In the microstructural modelling, the numerical simulation model is built on the basis of rock microstructure. In the micromechanical modelling, the model is constructed on the basis of the Weibull theory.The modelled results from single particle tests of three granites, i.e. Ävja, LEP and Vändle under BTS, point-to-point, plane-to-plane, point-to-plane and multiple-point loading conditions using microstructural modelling and micromechanical modelling show that Ävja is weaker than LEP and Vändle in terms of the aggregate tensile strength and applied work. The microstructural modelling also reveals that LEP is weaker than Vändle but the micromechanical modelling indicates that LEP and Vändle have similar mechanical properties.From this work it is concluded that microscope texture quantification and computer simulation is a promising approach to analyse mechanical properties of rock aggregates. Numerical modelling of the DSC test shows the potential to simulate multi particle chamber compression tests for assessment of rock aggregate quality. In general, the texture properties work together to influence the mechanical properties of rock aggregates. Computer simulation using a heterogeneous material model provides a valuable tool to investigate the relationship between the textural properties and mechanical properties of rock aggregates by taking main textural properties into consideration. In particular, for the three rocks in this study, micro crack size distribution, grain perimeter and grain size show strong correlations with the mechanical properties, e.g. for DSC strength: cracks and grain size negatively affect the mechanical properties but the perimeter positively influences the mechanical properties.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Arm, Maria, et al.
(författare)
-
Förutsägelse av långtidsegenskaper hos restprodukter : teknik och miljö i vägar
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, use of industrial by-products is still hindered by concern for their long-term properties. This report describes a three-year research project aiming to identify the key processes of ageing related to the usefulness of by-products in roads; investigate the consequences of these processes for technical and environmental properties of the by-products, and propose a method for accelerated ageing to predict long-term properties. The project has compared naturally aged samples of two by-products used as sub-bases in existing asphalt paved roads with samples of fresh by-products from producers' piles. Steel slag of electric arc furnace type and municipal solid waste incinerator (MSWI) bottom ash were chosen. The samples were thoroughly characterized in order to identify which ageing processes had been crucial. The working hypothesis was that ageing processes lead to changes in pH, effective particle size and mineralogy, which in turn determine leaching, stiffness and stability of the material. One of the conclusions from the project is that the test results confirmed that the pavement edge material is ageing faster than the road centre material is.
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| 10. |
- Arm, Maria, et al.
(författare)
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Technical environmental long-term properties of industrial residues : summary of field and laboratory investigations
- 2011
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 31:1, s. 101-107
-
Tidskriftsartikel (refereegranskat)abstract
- In Sweden, use of industrial residues is still hindered by concern for their long-term properties. A three-year research project was therefore initiated aiming to (1) identify the crucial processes of ageing related to the usefulness of residues in roads; (2) investigate the consequences of these processes for technical and environmental properties of the residues, and (3) propose a method for accelerated ageing to predict the long-term properties. This paper gives an overview of the project methodology, a summary of the test results and references to papers where further details are given. The project, running through 2006-2008, compared naturally aged samples of two residues used as sub-bases in existing asphalt paved roads with samples of fresh residues from producers' piles. Steel slag of electric arc furnace (EAF) type and municipal solid waste incinerator (MSWI) bottom ash were chosen. The samples were thoroughly characterised in order to identify which ageing processes had been crucial. The results showed that: - Bottom ash from the pavement edge was more aged than bottom ash from the road centre. However, no difference in pH was found, instead the differences were caused by differences in water exposure. - Steel slag from the pavement edge showed traces of carbonation and leaching processes, whereas slag from the road centre was identical to fresh slag. - Water exposure to the subbase materials after ten years in an asphalt paved road was calculated to less than 0.1–0.5 litres per kg. - Ageing reactions in steel slag and MSWI bottom ash, ready for use, were too small to be verified by laboratory measurement of deformation properties under loaded conditions. An accelerated ageing test for steel slag was set up to achieve the carbonation (decrease in pH) and leaching that was observed in the pavement edge material. An accelerated ageing test for bottom ash was set up to achieve the pozzolan reactions that were observed in SEM analyses of in situ specimens. It is recommended to use uncrushed particles when properties of aged material are studied, in order to preserve the original particle surfaces.
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| 11. |
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| 12. |
- Blomberg, Lars, et al.
(författare)
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Electric Field Diagnostics in the Jovian System : Brief Scientific Case and Instrumentation Overview
- 2006
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Ingår i: Proceedings of the 6th IAA International Conference on Low-Cost Planetary Missions. ; , s. 335-340
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Jovian plasma environment exhibits a variety of plasma flow interactions with magnetised as well as unmagnetised bodies, making it a good venue for furthering our understanding of solar wind - magnetosphere / ionosphere interactions. On an overall scale the solar wind interacts with the Jovian magnetosphere, much like at Earth but with vastly different temporal and spatial scales. Inside the Jovian magnetosphere the co-rotating plasma interacts with the inner moons. The latter interaction is slower and more stable than the corresponding interaction between the solar wind and the planets, and can thus provide additional information on the principles of the interaction mechanisms. Because of the wealth of expected low-frequency waves, as well as the predicted quasi-static electric fields and plasma drifts in the interaction regions between different parts of the Jovian system, a most valuable component in future payloads would be a double-probe electric field instrument. Recent developments in low-mass instrumentation facilitate electric field measurements on spinning planetary spacecraft, which we here exemplify.
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| 13. |
- Dias Ferreira Da Silva, Nelson, 1978, et al.
(författare)
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CHLORIDE CONTENTS AT THE CONCRETE-STEEL INTERFACE
- 2010
-
Ingår i: Advances in Concrete Strutural Durability - Proceedings of the 2nd International Conference on Durability of Concrete Structures ICDCS2010, 24-26 November 2010, Hokkaido University, Sapporo, Japan, edited by Hiroshi Yokota, Takafumi Sugiyama and Tamon Ueda, Hokkaido University Press. - 9784832903609 ; , s. 275-284
-
Konferensbidrag (refereegranskat)abstract
- The composition and microstructure of the concrete-steel interface influences the criticalchloride content (Ccr) for initiation of pitting corrosion and can differ from the conditions inthe bulk concrete. This paper describes the development of a methodology for chlorideprofiling along the interface by means of LA-ICP-MS. SEM-EDS and XRD techniques wereused for semi-quantitative analysis of Ccr, microstructure characterization of the pittingpositions and distribution and composition of the corrosion products. A range of chloridelevels along the interface was measured by means of LA-ICP-MS showing good agreementwith the results from EDS analysis. A number of interface defects were found to influencepitting corrosion. Several Fe(III) oxy-hydroxides, including akaganeite, were identified. XRDanalysis suggested the existence of FeCl2. These corrosion products tended to accumulate atthe aggregate-paste interface and in air voids at the cement paste.
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| 14. |
- Dias Ferreira Da Silva, Nelson, 1978, et al.
(författare)
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Chloride profiles along the concrete-steel interface
- 2013
-
Ingår i: International Journal of Structural Engineering. - 1758-7328 .- 1758-7336. ; 4:1/2, s. 100-112
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Tidskriftsartikel (refereegranskat)abstract
- The composition and microstructure of the concrete-steelinterface influences the critical chloride content for initiation of pitting corrosion and these characteristics may differ from those of the bulk concrete. This paper describes the development of a methodology for chloride profiling along the interface by means of LA-ICP-MS. For semi-quantitative analysis, microstructure characterisation of the pitting positions and distribution and composition of the corrosion products, SEM-EDS and XRD techniques wereemployed. The results indicate that along the interface a range of chloride levels can be expected. These varied between 0.15–1.5 wt% of concrete with higher levels around the active corrosion sites. Good agreement has been foundbetween the results from LA-ICP-MS and EDS techniques. Interface defects strongly influenced the pitting corrosion. Several Fe(III) oxy-hydroxides accumulated at the aggregate-paste interface and in air voids at the cementpaste. XRD analysis suggested the presence of akaganeite and FeCl2 (rokuhnite).
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| 15. |
- Dias Ferreira Da Silva, Nelson, 1978, et al.
(författare)
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Critical Conditions for Depassivation of Steel in Concrete: Interface Chloride Profiles
- 2011
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Ingår i: Nordic Concrete Research. ; Publication No. 43, s. 115-118
-
Konferensbidrag (refereegranskat)abstract
- This paper describes an ongoing research project that aims to improve the knowledge and understanding of the critical conditions for depassivation of steel by studying the micro/meso-scale chloride profiles along the steel-concrete interface and correlating these with aspects of its microstructure and composition.
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| 16. |
- Dias Ferreira Da Silva, Nelson, 1978, et al.
(författare)
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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.
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| 17. |
- Eriksson, Anders, et al.
(författare)
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RPC-LAP : The Rosetta Langmuir probe instrument
- 2007
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Ingår i: Space Science Reviews. - : Springer Science and Business Media LLC. - 0038-6308 .- 1572-9672. ; 128:04-jan, s. 729-744
-
Forskningsöversikt (refereegranskat)abstract
- The Rosetta dual Langmuir probe instrument, LAP, utilizes the multiple powers of a pair of spherical Langmuir probes for measurements of basic plasma parameters with the aim of providing detailed knowledge of the outgassing, ionization, and subsequent plasma processes around the Rosetta target comet. The fundamental plasma properties to be studied are the plasma density, the electron temperature, and the plasma flow velocity. However, study of electric fields up to 8 kHz, plasma density fluctuations, spacecraft potential, integrated UV flux, and dust impacts is also possible. LAP is fully integrated in the Rosetta Plasma Consortium (RPC), the instruments of which together provide a comprehensive characterization of the cometary plasma.
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| 18. |
- Eriksson, Jonny, 1963, et al.
(författare)
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Development of mortars in Sweden during the period 1800 to 1950
- 2016
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Ingår i: 4th Historic Mortars Conference HMC 2016. Santorini, Greece, 10-12 October, 2016.. ; , s. 204-210
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Konferensbidrag (refereegranskat)abstract
- The objective with the present project was to combine studies of textbooks and masonry constructions with laboratory analyses of historical mortars from the time period 1800 to 1950. The objective was to investigate the development of knowledge and craftsmanship of the mason during this period. The three different sources display the same trends from binder rich to binder poor and to mortars based on cement and lime mixes. There was a change from a complex and varying use of different mortars in the 19th century to a simplified and standardized use in the 20th century. This process also includes a change to a centralised and industrialized production of binders. A consequence of this was that a loss of the craftmans knowledge of how to handle different hydraulic binders and pozzolans. The later part of the period was characterised in a loss of knowledge in this aspect for all actors working with masonry and renders.
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| 19. |
- Eriksson, Jonny, 1963, et al.
(författare)
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Lime render, shrinkage cracks and craftsmanship in building restoration
- 2019
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Ingår i: Journal of Cultural Heritage. - : Elsevier BV. - 1296-2074 .- 1778-3674. ; 37, s. 73-81
-
Tidskriftsartikel (refereegranskat)abstract
- The present project concerns early shrinkage cracks in renders. This problem relates to the type of lime and rendering methods used in Sweden during the 19th and early 20th century as well as in current restoration practice. Results from different render restoration projects have indicated that a high frequency of shrinkage cracks could be related to the slaking procedure and the reworking of the slaked lime putty. The aim of the project was to investigate whether there is a connection between different handling procedures for wet-slaked lime putty and early shrinkage cracks in render. An investigation involving practical application and a laboratory test programme was initiated to examine the problem of early shrinkage cracks in renders based on wet-slaked sub-hydraulic lime. This type of lime was commonly used in Sweden in the 19th century. The laboratory work in the project included 3 different mix proportions based on reworked and non-reworked lime putty. The renders were applied after 1, 8, 15, 32 and 68 days storage of the lime putty. This gave 30 mortar mixes applied as rendered test surfaces. The flow number of the fresh mortars was determined and the workability, mixability and open time were assessed. The frequency of shrinkage cracks in the rendered surfaces was measured. The results showed that the frequency of shrinkage cracks was related to the methods applied in the slaking process and the storage time. Reworking and storage of the lime putty increased the frequency of shrinkage cracks. The properties of the fresh mortar were also influenced.
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| 20. |
- Flansbjer, Mathias, et al.
(författare)
-
Mechanical behaviour of concrete piles affected by sulphate attack
- 2013
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Ingår i: Proceeding of the International IABSE Conference. - 9783857481239 ; , s. 389-392, s. 556-557
-
Konferensbidrag (refereegranskat)abstract
- Assessing the remaining service life is vital for the planning of maintenance of concrete constructions in aggressive environments. Here we present results from testing of two concrete piles affected by sulphate attack in marine environment. A multi-method approach going from micro scale to structural level has been applied. The crack propagation was monitored during loading by means of DIC and AE. After the test crack patterns was studied using fluorescence microscopy. Furthermore, non-linear finite element analysis at the structural level was used to study the influence of the chemical attack on the response of concrete piles.
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| 21. |
- Flansbjer, Mathias, et al.
(författare)
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Mechanical behaviour of concrete piles affected by sulphate attack
- 2012
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Ingår i: Proceeding of fib Symposium: Concrete Structures for Sustainable Community, 11 – 12 June 2012, Stockholm, Sweden. ; , s. 389-392
-
Konferensbidrag (refereegranskat)abstract
- Assessing the remaining service life is vital for the planning of maintenance of concrete constructions in aggressive environments. Here we present results from testing of two concrete piles affected by combined sulphate and chloride attack in marine environment. A multi method approach going from micro scale to structural level has been applied. The crack propagation was monitored during loading by means of DIC and AE. After the test crack patterns was studied using fluorescence microscopy. Furthermore, non-linear finite element analysis at the structural level was used to study the influence of the chemical attack on the response of concrete piles.
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| 22. |
- Flansbjer, Mathias, et al.
(författare)
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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
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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.
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| 23. |
- Flansbjer, Mathias, et al.
(författare)
-
Methodology for Mesomechanical Study of Concrete Material
- 2017
-
Konferensbidrag (refereegranskat)abstract
- This project focuses on detailed studies of how the cracking process in concrete is influenced by the concrete micro- and mesostructure. The aim is to increase knowledge of how critical parameters affect 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 scale levels has been 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 the test, crack patterns were studied using fluorescence microscopy.
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| 24. |
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| 25. |
- Flansbjer, Mathias, et al.
(författare)
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Quantitative Characteristics in Shear Load
- 2011
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Ingår i: <em>fib</em> Symposium PRAGUE 2011 - Proceedings. ; , s. 567-570
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 26. |
- Flansbjer, Mathias, et al.
(författare)
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Quantitative fracture characteristics in shear load
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Today, no general design method for shear strength capacity of RC beams can predict the failure load with a high degree of accuracy. The failure load between two beams cast from the same batch may vary as much as 30 percent. This project aims at investigating factors affecting the shear strength capacity based on an understanding of micro and meso scale material properties. Tests were performed on beams with two different types of aggregate and two different w/c. The crack propagation was monitored during the loading by means of DIC and AE. The results show that the use of natural aggregates or crushed aggregates as finer fractions strongly affect the shear strength capacity. From direct shear tests it was found that the scatter of the shear strength was much higher for the specimens with natural aggregates compared with crushed aggregates. The same tendency was found for the shear crack initiation load for the RC beams. The percentage of fractures propagating through aggregate, paste and the ITZ varied with w/c, type of aggregate and type of failure. Microscopy in combination with DIC and AE measurements makes it possible to determine at what stage different cracks have been formed and their relation to the micro structure.
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| 27. |
- Flansbjer, Mathias, et al.
(författare)
-
Visual assessment of fire damaged concrete
- 2011
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Ingår i: BrandPosten. ; :44, s. 12-13
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Fire can reduce the load-carrying capacity of concrete structures. A new innovative method, Optical Deformation Measurement, can be used to determine how far into the concrete damage has penetrated. The method involves measurements on test cores from the damaged structure.
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| 28. |
- Frogner-Kockum, Paul Christian, et al.
(författare)
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Long-term performance of MSWI Bottom ash in a test road construction
- 2016
-
Ingår i: International Journal of Sustainable Construction Engineering and Technology. - 2180-3242. ; 7:1
-
Tidskriftsartikel (refereegranskat)abstract
- The study focuses on long-term performances of MSWI bottom ash used as a reinforcement layer in a 8 years old road-construction. Long term properties may change under the combined effects of loading, climate- and chemical conditions. Characterization of the chemical changes in aged MSWI bottom ash is thus of prime interest as secondary alteration is a key process for the ageing of these kind of materials. The MSWI bottom ash in this study comprises a 60 meter-long segment of a test road, which was sampled eight years after construction. The objective of the sampling was to obtain a very low degree of disturbance to the application’s in-situ properties. Access to the sub-base was achieved by removing the surface course and unbound base course, leaving the top surface of the unbound sub-base reachable. Epoxy impregnated slabs were also used for a micro textural and chemical characterization by SEM/EDS of the bottom ash sub-base layer. No cracks that imply movements or rotation of particles in the road construction or other disturbances as due to the sampling process were found. This undisturbed material made it possible to study chemical processes and structural changes that have been ongoing in the test road since it was constructed. The SEM/EDS analysis showed that most particles had reacted to some extent and that reaction-products surrounding aluminum particles were undisturbed. Partly decomposed particles indicate that the reaction (that has been ongoing since the road was constructed) has been slow and incomplete because of the coexistence of metallic aluminum and aluminum hydroxide. It also shows that the material not has been subjected to any physical influence during these 8 years that otherwise would have moved the reaction products from the particles that originally have reacted. Clay mineralization that indicates long-term ageing of the ash material was also detected by XRPD. The pH of the material was lower than 8.5, indicating a mature degree of carbonization. It is also concluded from the study that chemical reactions consistent with this maturity have been taking place in the road construction as indicated by textural relationships.
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| 29. |
- Groot, Caspar, et al.
(författare)
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RILEM TC 203-RHM: Repair mortars for historic masonry : Performance requirements for renders and plasters
- 2012
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Ingår i: Materials and Structures. - 1359-5997 .- 1871-6873. ; 45:9, s. 1277–1285-
-
Tidskriftsartikel (refereegranskat)abstract
- This article gives a summary of functional_x000D_ and performance requirements for renders and plasters_x000D_ for historic masonry (design, execution and maintenance)._x000D_ Specific attention has been paid to degradation_x000D_ effects, such as caused by salt crystallization and_x000D_ freeze–thaw cycling. Traditional as well as designed_x000D_ prefab mortars are considered for repair intervention.
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| 30. |
- Hughes, JJ, et al.
(författare)
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RILEM TC 203-RHM: Repair mortars for historic masonry : The role of mortar in masonry: an introduction to requirements for the design of repair mortars
- 2012
-
Ingår i: Materials and Structures. - 1359-5997 .- 1871-6873. ; 45:9, s. 1287–1294-
-
Tidskriftsartikel (refereegranskat)abstract
- Mortar has been in use for many thousands of years and is integral to most masonry construction. Its use is widespread in every culture where masonry is constructed. It is present in the majority of the global built cultural heritage, and is therefore a major consideration in building conservation. The effective design of a mortar for repairing masonry depends on a clear understanding of its function. The main functional uses of mortar in masonry are classified as bedding, pointing, grout, render, plaster, flooring and mortars for surface repairs. The requirements that each type of mortar must meet in service depend on its environmental exposure and its role in the masonry element that it is found within (e.g. issues such as historic authenticity, aesthetics, resistance to moisture ingress, structural integrity, and service life). Technical requirements such as adhesion, strength, elasticity, water and vapour transmittance, drying behaviour, thermal dilatation, ability to deal with salt contamination and freeze-thaw cycling, and its aesthetic properties can be quantified. Mortar properties can be adjusted by varying ingredients and their proportions, to meet the differing technical requirements.
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| 31. |
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| 32. |
- Hultgren, Stefan, et al.
(författare)
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Sleep disturbances in outpatients with ankylosing spondylitisa questionnaire study with gender implications
- 2000
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Ingår i: Scandinavian Journal of Rheumatology. - 0300-9742 .- 1502-7732. ; 29:6, s. 365-369
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the sleep pattern in ankylosing spondylitis, and to investigate gender differences in sleep, pain, and fatigue. METHODS: Forty-three male and 27 female patients with ankylosing spondylitis completed a sleep questionnaire and the results were compared with earlier findings in 3,558 persons randomly selected from the general population. RESULTS: Too little sleep was reported by 80.8% of the female and 50.0% of the male patients, compared to 28.8% and 21.8% respectively in the reference group (p<0.0001). The main reason was pain in the pre-sleep and sleep-periods (p<0.0001). Daytime fatigue was a major problem (p<0.0001). Higher correlation was found between pain and daytime fatigue than between sleep disturbance and daytime fatigue. CONCLUSION: Sleep disturbance is a significant problem in ankylosing spondylitis. The disturbance is closely related to pain at bedtime and during the night. Gender differences exist in the subjective sleep disturbance, fatigue, and pain.
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| 33. |
- Jacobsson, Lars, et al.
(författare)
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Laboratory investigation of crack initiation on hourglass-shaped granite specimens
- 2018
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Ingår i: Geomechanics and Geodynamics of Rock Masses, Volume 1: Proceedings of the 2018 European Rock Mechanics Symposuim. - London : CRC Press. - 9780429461774 - 9780429867729 ; , s. 633-638
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Konferensbidrag (refereegranskat)abstract
- Laboratory experiments on axially compressed hourglass-shaped specimens of medium to coarse grained granite specimens were conducted. A tangential stress is generated in the circular notches which is intended to initiate surface spalling similar to what can be seen at circular openings in a rock mass. Specimens of three different sizes were tested with notch radii 98.4, 225 and 375 mm, which are equivalent to a hole diameter of 197, 450 and 750 mm. The spalling initiation and progress in the notches were monitored by acoustic emission and digital correlation measurements. From the acoustic emission measurements it could be seen that the tangential stress at spalling initiation decreased with increasing notch radius. Results from digital image correlation show how the surfaces in local zones in the notch were pushed outwards due to subsurface cracking parallel to the notch surface. Analyses of thin sections and polished slabs taken in the notch area showed that the cracking depth increased with increasing notch radius.
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| 34. |
- Jacobsson, Lars, et al.
(författare)
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Laboratory investigation of stress gradient effect at spalling experiments on granite
- 2015
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Ingår i: The 13th International Congress of Rock Mechanics. - 9781926872254
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Konferensbidrag (refereegranskat)abstract
- A series of laboratory tests were conducted to study stress-induced spalling on medium to coarse-grained granite specimens. The specimens made from cylinders had two manufactured notches on opposite sides aimed to represent the tangential loading around a circular opening. Specimens of three different sizes were tested with notch radii, 98.5, 225 and 375 mm, representing 197, 450 and 750 mm diameter holes, to study the effect of notch radius on the spalling initiation stress. The cracking was monitored by acoustic emission sampling. The fracture patterns were investigated visually on polished slabs and by microscopy on thin sections. The crack analysis describes how the cracks propagate in relation to the grain structure in the rock and to the macroscopic stress field.
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| 35. |
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| 36. |
- Jacobsson, Lars, et al.
(författare)
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Spalling initiation experimentson large hard rock cores
- 2018
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Rapport (refereegranskat)abstract
- A new type of laboratory test method to determine spalling resistance in a situation as in large boreholes in hard rock has been demonstrated. Uniaxial compression tests on large cores with notches were conducted on Äspö diorite from Äspö HRL. Spalling was localized to the notches where the local stress was highest. The crack initiation, crack coalescence and crack damage stresses representing various fracture stages were identified by using acoustic emission monitoring with source localization. The actual stress levels were obtained from the axial forces at which the various fracture stages were identified via FE-calculations representing the actual specimen geometry and loading. The results were compared with uniaxial compression tests carried out on cores with standard size on the same rock type also from Äspö HRL.The results showed that spalling chips were formed similar to those found in field which indicates that the test is representing a realistic behaviour. However, the results show that the various fracture stress levels found in the tests are higher than the spalling strength found in the field and in the test of small cores. The higher stress levels could be caused by a number of reasons described in the report.A post characterization of the fractures was carried out on slabs that were cut out from the specimens containing the notch areas. The occurrence of microcracks and how they have propagated through the different minerals and the location in relation to the notches, minerals and grain boundaries were investigated. The patterns of the major fractures and the secondary fractures were analysed. The majority seem to be extension fractures, but shearing could also be verified. The results from the microscopy analysis provide invaluable information of the spalling process at all stages.
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| 37. |
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| 38. |
- Lindqvist Appell, Malin, 1976-, et al.
(författare)
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Identification of two novel sequence variants affecting thiopurine methyltransferase enzyme activity
- 2004
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Ingår i: Pharmacogenetics. - : Ovid Technologies (Wolters Kluwer Health). - 0960-314X .- 1473-561X. ; 14:4, s. 261-265
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Tidskriftsartikel (refereegranskat)abstract
- The polymorphic enzyme thiopurine methyltransferase (TPMT) is involved in the methylation of thiopurines. On comparing the phenotype with the genotype in Swedish patients with inflammatory bowel disease and healthy individuals, we found two discordant cases with low TPMT enzyme activity (0.3 and 0.4 U/ml packed red blood cells (pRBC). Genotyping by pyrosequencing revealed that they carried the nucleotide substitutions 460G>A and 719A>G, giving two possible genotypes (TPMT*1/*3A or TPMT*3B/ *3C). DNA sequencing of exon III to X was performed in the patients and their parents. We identified an A>G transition in the start codon (exon III, 1A>G, Met>Val, TPMT*14) in one of the patients and her father (6.3 U/ml pRBC). The mother in this family carried the 460G>A and 719A>G nucleotide substitutions (TPMT*3A, 5.0 U/ml pRBC). In the second family, sequencing revealed a G>A transition in the acceptor splice site in intron VII/exon VIII (IVS7 - 1G>A, TPMT*15) in the patient and his mother (6.9 U/ml pRBC). His father was genotyped as TPMT*1/*3A (6.0 U/ml pRBC). Hence, we report the identification of two novel sequence variants, present in highly conserved nucleotide positions of the human TPMT gene, resulting in a loss of enzyme activity.
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| 39. |
- Lindqvist, Jan-Erik
(författare)
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Analysis of mortars with additives
- 2005
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Rapport (refereegranskat)abstract
- Existing methods for the analysis of masonry and rendering mortars were developed for the analysis of well defined simple mortars. Mortars used today are to a large extent hybrid mortars with different additives and filler. Analysing complex mortars with additives and fillers requires analytical routines that are more versatile. In order to investigate the possibilities for characterisation of mortars using chemical and microscopical methods, test prisms were produced from lime cement mortars with dolomite filler and from lime cement slag mortars. After six months of hardening, the prisms were prepared for chemical and microscopical thin-section analysis. Acid-soluble components in the samples were analysed chemically and the constituents were quantified by optical microscopy using point counting and counting in fields. From these results the mix proportions were calculated. The chemical methods gave an assessment of the mix proportions calculated using a general algorithm. The calculation of the quantitative results based on microscopy was done according to the NT BUILD 370 method and the TNO method. These gave a good assessment of the lime cement mortars and the slag mortars with low slag content. However, the analysis of mortars with high slag content gave aggregate-binder ratios that were too low. The obtained results show that the combination of microscopical and chemical methods can provide a good assessment of the proportions used when mixing the mortars. Key words: mortar lime cement slag chemical microscopical
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| 40. |
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| 41. |
- Lindqvist, Jan-Erik, et al.
(författare)
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Assessment of mechanical durability properties of rock materials using quantitative microscopy and image analysis
- 2003
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Rapport (refereegranskat)abstract
- This report presents a project that focuses on the assessment of mechanical durability properties using quantitative microscopy. The project was financed by SGU under grant 03-1174/98. The aim has been to develop methods for assessment and presentation of rock quality data. Both optical and SEM/BSE microscopy were applied and combined with computerised image analysis and manual methods for the quantitative analysis. The first part of the project was to produce a literature overview of image analysis as applied to rock materials. A method for assessment of resistance to fragmentation of granitic rocks comparable with the Los Angeles test has been developed. By means of a quantitative description of foliation using a foliation index, FIX, it is possible to assess the potential length-thickness ratio of the crushed aggregate. Methods developed in the main part of the project have been applied in related areas. These include crack initiation and propagation under cyclic loading and cyclic thermal stress.
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