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de Frias Lopez, R., Larsson, S. & Silfwerbrand, J. (2019). A discrete element material model including particle degradation suitable for rockfill embankments. Computers and geotechnics, 115, Article ID 103166.
Open this publication in new window or tab >>A discrete element material model including particle degradation suitable for rockfill embankments
2019 (English)In: Computers and geotechnics, ISSN 0266-352X, E-ISSN 1873-7633, Vol. 115, article id 103166Article in journal (Refereed) Published
Abstract [en]

A material model for future implementation in high rockfill embankments has been developed using discrete elements. Compared to previous modelling of railway ballast representing particles as clumps of spheres with bonded asperities, much simpler breakable clumps are used. This allows considering not only corner breakage but also particle splitting without a prohibitive computational time, something unique when modelling three-dimensional assemblies of particles. Moreover, breakage is controlled by values of contact forces and particle loading configuration, resulting in significantly fewer parameters and with a much clearer physical meaning. All in all, it results in a more computationally efficient and robust model suitable for implementation in rockfill embankments. Numerical monotonic and cyclic triaxial tests are performed under a range of low deviatoric to confinement stress ratios, as anticipated for railway embankments. A comparable degree of resemblance to empirical results as the previous modelling efforts with bonded asperities is observed when including degradation. Results at particle level proved useful to partially explain the observed macroscopic responses; however, these were substantially affected by breakage and none of the studied variables could, on its own, satisfactorily fully explain the observed behaviour. As a matter of fact, a complex interdependency of different factors, both at particle and macroscopic level, was identified that ultimately explained the macroscopic response. The key contribution is thus presenting an efficient and realistic material model specifically aimed at modelling high rockfill embankments including degradation, something not attempted to date.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Discrete element modeling, Granular materials, Rockfill embankment, Particle-scale behavior, Particle degradation
National Category
Geotechnical Engineering
Research subject
Civil and Architectural Engineering, Soil and Rock Mechanics
Identifiers
urn:nbn:se:kth:diva-263509 (URN)10.1016/j.compgeo.2019.103166 (DOI)000506718800008 ()2-s2.0-85071493258 (Scopus ID)
Note

QC 20191202

Available from: 2019-12-02 Created: 2019-12-02 Last updated: 2020-02-14Bibliographically approved
Silfwerbrand, J. & Mohaghegh, A. M. (2019). Basaltfiberbetong för marina miljöer. Betong (3), pp. 56-58
Open this publication in new window or tab >>Basaltfiberbetong för marina miljöer
2019 (Swedish)In: Betong, ISSN 1101-9190, no 3, p. 56-58Article in journal, News item (Other (popular science, discussion, etc.)) Published
Place, publisher, year, edition, pages
Stockholm: , 2019
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-261196 (URN)
Note

QC 20191003

Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2019-10-03Bibliographically approved
Hellström, A. & Silfwerbrand, J. (2019). Beräkna stommars livslängd till 400 år. Betong (1), 57-58
Open this publication in new window or tab >>Beräkna stommars livslängd till 400 år
2019 (Swedish)In: Betong, ISSN 1101-9190, no 1, p. 57-58Article in journal (Other (popular science, discussion, etc.)) Published
Place, publisher, year, edition, pages
Stockholm: , 2019
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-261197 (URN)
Note

QC 20191003

Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2019-10-03Bibliographically approved
Rogers, P., Silfwerbrand, J., Selander, A. & Gram, A. (2019). Bulk Hydrophobic Civil Engineering Concrete For Nordic Conditions – Freeze Thaw Action. In: Wit Derkowski et al. (Ed.), : . Paper presented at fib Symposium 2019 - Concrete - Innovations in Materials, Design and Structures, Kraków, Poland May, 27-29 2019..
Open this publication in new window or tab >>Bulk Hydrophobic Civil Engineering Concrete For Nordic Conditions – Freeze Thaw Action
2019 (English)In: / [ed] Wit Derkowski et al., 2019Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Concrete is a compositebuilding material which long term function can be modified for example bychanging the water to cement ratio (w/c) or by adding in other chemicaladmixtures to change the fresh and hardened properties of the concrete. Theoverall goal of this study is to reduce the water absorption capacity of thecement paste/microstructure by at least 85 %. This is achieved by using bulkhydrophobic agents in the mixing phase rather than post hardened surfaceapplication. Numerous commercial agents and triglycerides (vegetable oils) weretested and showed promising results at a dosage equal to 3% of cement weight.This though affected compressive strengths negatively. As these concretes willbe exposed to Nordic winter conditions, the concrete should perform well underrepeated salt water freezing and thawing. This continued study will show how aselection of these bulk hydrophobic concretes performed during this part of thestudy. The concrete has a w/c = 0.4 with a cement content (CEM I) of 430 kg/m3

National Category
Other Materials Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-255843 (URN)
Conference
fib Symposium 2019 - Concrete - Innovations in Materials, Design and Structures, Kraków, Poland May, 27-29 2019.
Funder
Swedish Transport Administration, 2017/57524Rock Engineering Research Foundation (BeFo), 383
Note

QC 20190821

Available from: 2019-08-13 Created: 2019-08-13 Last updated: 2019-08-21Bibliographically approved
Rogers, P., Silfwerbrand, J., Gram, A. & Selander, A. (2019). Bulk Hydrophobic Civil Engineering Concrete for Nordic Conditions: Freeze Thaw Action. In: : . Paper presented at fib Symposium 2019, Concrete - Innovations in Materials, Design and Structures, May, 27-29, 2019, Krakow, Poland.
Open this publication in new window or tab >>Bulk Hydrophobic Civil Engineering Concrete for Nordic Conditions: Freeze Thaw Action
2019 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Concrete is a composite building material which long term function can be modified for example by changing the water to cement ratio (w/c) or by adding in other chemical admixtures to change the fresh and hardened properties of the concrete. The overall goal of this study is to reduce the water absorption capacity of the cement paste/microstructure by at least 85 %. This is achieved by using bulk hydrophobic agents in the mixing phase rather than post hardened surface application. Numerous commercial agents and vegetable oils were tested and showed promising results at a dosage equal to 3% of cement weight. This though affected compressive strengths negatively. As these concretes will be exposed to Nordic winter conditions, the concrete should perform well under repeated salt water freezing and thawing. This continued study will show how a selection of these bulk hydrophobic concretes performed during this part of the study. The concrete has a w/c = 0.4 with a cement content (CEM I) of 430 kg/m3.

Keywords
Bulk hydrophobic concrete, siloxanes, vegetable oils, freeze thaw action, thin section analysis
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-261190 (URN)
Conference
fib Symposium 2019, Concrete - Innovations in Materials, Design and Structures, May, 27-29, 2019, Krakow, Poland
Note

QC 20191008

Available from: 2019-10-02 Created: 2019-10-02 Last updated: 2019-10-08Bibliographically approved
Andersson, L., Silfwerbrand, J., Selander, A. & Trägårdh, J. (2019). Continuous Preventive Bridge Maintenance in Sweden – Field Experiment on the Effect of Washing on Concrete Bridges. In: Proceedings of the fib Symposium 2019: Concrete - Innovations in Materials, Design and Structures: . Paper presented at fib symposium, Krakow, 2019.
Open this publication in new window or tab >>Continuous Preventive Bridge Maintenance in Sweden – Field Experiment on the Effect of Washing on Concrete Bridges
2019 (English)In: Proceedings of the fib Symposium 2019: Concrete - Innovations in Materials, Design and Structures, 2019Conference paper, Published paper (Refereed)
Abstract [en]

Bridges are an important part of the infrastructure. For the 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 effects of washing is heavily discussed but not properly researched. A study on the effectiveness of washing concrete is therefore being conducted. A field experiment has been initiated where concrete specimens are installed on an edge beam of a road bridge. The specimens are of two recipes where one represents an old bridge with rather high water-cement ratio and the other one represents a new bridge with a low water-cement ratio. 50% of the specimens are washed annually, while the others are not. Each year samples are collected and tested for a chloride profile. The results for the first year of exposure have been determined. They are promising but are still only very preliminary. The effect of washing, if any, will be visible after a longer exposure.

Keywords
Bridge maintenance; Field experiment; Preventive maintenance; Washing
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-261189 (URN)2-s2.0-85066104402 (Scopus ID)
Conference
fib symposium, Krakow, 2019
Note

QC 20191007

Available from: 2019-10-02 Created: 2019-10-02 Last updated: 2019-10-07Bibliographically approved
Brochner, J. & Silfwerbrand, J. (2019). Performance of performance specifications in design-build highway projects. Australasian Journal of Construction Economics and Building, 19(2), 111-125
Open this publication in new window or tab >>Performance of performance specifications in design-build highway projects
2019 (English)In: Australasian Journal of Construction Economics and Building, ISSN 1835-6354, E-ISSN 1837-9133, Vol. 19, no 2, p. 111-125Article in journal (Refereed) Published
Abstract [en]

Design-build contracts with performance-based specifications are believed to raise productivity and the innovation rate. Such specifications for highway and bridge contracts may create risks, be too detailed or difficult to verify. The purpose has been to analyse how performance-based requirements are used in Swedish design-build contracts for highway projects. How contractors are encouraged to provide innovative technologies is emphasized. Generic documents from the Swedish Transport Administration for design-build contracts have been studied, and case studies of six design-build contracts with performance-based requirements have been made. Technical specifications for these contracts have been analysed and interviews held with both client and contractor project managers. Results include that it is along the time axis that major obstacles to innovation arise. Before the contractor is able to develop innovative solutions, the initial design plan restricts the highway geometry. During construction, a mix of performance and prescriptive requirement formulations is more of a challenge than clashes between performance requirements. The client may avoid performance language, more so for bridges than road surfaces, because of concerns with efficient maintenance in the future. It is recommended that performance-based specifications should be less detailed and that a life cycle view of highway projects should support innovative technologies.

Place, publisher, year, edition, pages
UNIV TECHNOLOGY, SYDNEY-UTS EPRESS, 2019
Keywords
Design-build contracting, Performance-based requirements, Highway construction, Maintenance, Sweden
National Category
Construction Management
Identifiers
urn:nbn:se:kth:diva-265979 (URN)10.5130/AJCEB.v19i2.6659 (DOI)000500702300001 ()2-s2.0-85076909703 (Scopus ID)
Note

QC 20191220

Available from: 2019-12-20 Created: 2019-12-20 Last updated: 2020-01-13Bibliographically approved
Emborg, M., Ohlsson, U., Persson, M. & Silfwerbrand, J. (2019). Slitbetong som brobeläggning. Betong (1), 43-46
Open this publication in new window or tab >>Slitbetong som brobeläggning
2019 (Swedish)In: Betong, no 1, p. 43-46Article in journal (Other (popular science, discussion, etc.)) Published
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-261198 (URN)
Note

QC 20191007

Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2019-10-07Bibliographically approved
Ahmed, L. & Silfwerbrand, J. (2018). Dynamic Measurements for Determining Poisson’s Ratio of Young Concrete. Nordic Concrete Research (58), 95-105
Open this publication in new window or tab >>Dynamic Measurements for Determining Poisson’s Ratio of Young Concrete
2018 (English)In: Nordic Concrete Research, ISSN 0800-6377, no 58, p. 95-105Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-235278 (URN)
Note

QC 20180920

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2019-06-05Bibliographically approved
Döse, M. & Silfwerbrand, J. (2018). Reduction of Radon Gas in Concrete Using Admixtures and Additives. Nordic Concrete Research, 58, Article ID ncr-2018-0002.
Open this publication in new window or tab >>Reduction of Radon Gas in Concrete Using Admixtures and Additives
2018 (English)In: Nordic Concrete Research, ISSN 0800-6377, Nordic Concrete Research, ISSN 2545-2819, Vol. 58, article id ncr-2018-0002Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Oslo: , 2018
Keywords
radon, effective dose, concrete, building materials, admixtures, additives, fly ash, health
National Category
Engineering and Technology
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-240430 (URN)
Note

QC 20190107

Available from: 2018-12-19 Created: 2018-12-19 Last updated: 2019-01-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1526-9331

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