| 1. |
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| 2. |
- Al-Ayish, Nadia, et al.
(författare)
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Safety and sustainability of new admixtures for durable concrete
- 2019
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Ingår i: Durable Concrete for Infrastructure Under Severe Conditions.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The sustainability of concrete infrastructures is highly dependent on the durability. A longer service life with low repair work reduces the resource use and hence the greenhouse gas emissions. New admixtures based on nanomaterials have the possibility to increase the service life. However, it is also important to consider the embodied impact of the material and safety issues concerning new nanomaterials. Here we present an overview on the latest developments on the safety and sustainability of some novel admixtures.
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| 3. |
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Analysis of the Flexural Behavior of Textile Reinforced Reactive Powder Concrete Sandwich Elements Using Optical Measurements
- 2018
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Proceedings (redaktörskap) (refereegranskat)abstract
- Prefabricated and non-load bearing sandwich façade elements were developed using Textile Reinforced Reactive Powder Concrete (TRRPC) along with low density Foamed Concrete (FC) and Glass Fiber Reinforced Polymer (GFRP) continuous connecting devices. Four-point bending tests were performed on large-scale TRRPC sandwich element beams to characterize the structural performance, which included the flexural capacity, level of composite action, resulting deformation, crack propagation and failure mechanisms. Optical measurements based on Digital Image Correlation (DIC) were taken simultaneously to enable a detailed analysis of the underlying composite action. The structural behavior of the developed elements was found to be highly dependent on the stiffness and strength of the connectors to ensure composite action between the two TRRPC panels.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Baba Ahmadi, Arezou, 1985, et al.
(författare)
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Utilization of Bio Ashes in Cement-based Materials: A Case Study in Cooperation with Pulp and Paper and Energy Production Industries in Sweden
- 2020
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Ingår i: Nordic Concrete Research. - : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 63:2, s. 63-78
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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.
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| 9. |
- Boubitsas, Dimitiros, et al.
(författare)
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Frost Resistance of Concrete – Experience from Long-Term Field Exposure
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report presents the results from a research project financed by Trafikverket, the Swedish Transport Administration, co-financed by Cementa AB.The purpose of this project is to investigate concrete specimens exposed to a de-icing salt highway environment at Highway 40 close to Borås after about 20 years. The project work was divided into two parts: Part One for frost resistance of concrete and Part Two for chloride ingress and reinforcement corrosion.In Part One, more than 100 types of concrete mixes with different binder types/combinations, water-binder ratios (w/b) and air contents exposed at three field test sites were examined for external and internal frost damage by measurements of the changes in volume of, and in ultrasonic transmission time through, the specimens. Furthermore, some laboratory tests were carried out to supply necessary data for modelling and identify the possible mechanisms causing frost damage.The results show clearly that the highway environment is the most aggressive with regard to external frost damage. Further, the results from this study show that the existence of entrained air and the water-binder ratio are the main parameters influencing the resistance of concrete to external salt-frost damage. Furthermore, the concrete mixes with CEM I, CEM I + 5 % silica, CEM II/A-LL, CEM II/A-S and CEM I + 30 % slag as binder with entrained air and a water/binder ratio of 0.4 or below, has good resistance to internal and external frost damage. Results show that concrete containing large amounts of slag as part of the binder (CEM III/B) have the severest scaling, irrespective of its content of entrained air.Comparing results from laboratory testing of salt-frost resistance in accordance with SS 13 72 44 (the ‘Slab test’ in CEN/TS 12390-9) with results after nineteen years’ exposure at the highway exposure site shows that the laboratory standard classifies most concrete qualities correctly.However, there is an indication that the laboratory test method may overestimate the scaling resistance of concrete containing a medium to high content of slag as part of the binder. This indicates a need to consider a revision of the slab test procedure so that aging processes is better taken into consideration. A somewhat longer preconditioning time with at least partially an increased carbon dioxide content would for example lead to that the effect of carbonation is better reflected.
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| 10. |
- Chozas, Valle, et al.
(författare)
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Synthesis and characterization of reactive powder concrete for its application on thermal insulation panels
- 2015
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Ingår i: IOP Conference Series. - : Institute of Physics Publishing (IOPP).
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Konferensbidrag (refereegranskat)abstract
- This paper describes the synthesis and characterization of a set of textile reinforced reactive powder concrete (RPC) mixes that have been prepared in the framework of the SESBE project which aims to develop facade panels for the building envelope. In order to reduce the environmental impact, high concentration of type I and II mineral additions were added to the mixtures (up to 40% of cement replacement). The mechanical properties of the materials were analysed showing high values of compression strength thus indicating no disadvantages in the compression mechanical performance (∼140 MPa) and modulus of elasticity. In order to enable the use of these materials in building applications, textile reinforcement was introduced by incorporating layers of carbon fibre grids into the RPC matrix. The flexural performance of these samples was analysed showing high strength values and suitability for their further utilization.
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| 11. |
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| 12. |
- Falchi, Laura, et al.
(författare)
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Influence and effectiveness of water-repellent admixtures on pozzolana-lime mortars for restoration application
- 2013
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 49, s. 272-280
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Tidskriftsartikel (refereegranskat)abstract
- Pozzolana-lime mortars modified with water-repellent admixtures were designed and studied to obtain mortars for restoration application. Powdered silane and calcium stearates were mixed with pozzolana, lime and sand and the chemical-physical properties of the resulting mortars were evaluated by X-ray diffraction, electron microscopy (SEM-EDX), thermogravimetric analysis and FT-IR spectroscopy. The mechanical behavior, the pore structure and the hygric behavior were measured. The resistance of water-repellent mortars to the salt crystallization was evaluated. Both calcium stearates and powdered silane allowed good water-repellent protection even if the water-repellent agents and their dosage modified some physical properties and the hydration kinetic.
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| 13. |
- Falchi, Laura, et al.
(författare)
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The influence of water-repellent admixtures on the behaviour and the effectiveness of Portland limestone cement mortars
- 2015
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Ingår i: Cement & Concrete Composites. - : Elsevier. - 0958-9465 .- 1873-393X. ; 59, s. 107-118
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Water-repellent mortars were prepared using different hydrophobic compounds as admixtures. Calcium and zinc stearates, silane/siloxane products (as liquid solution and powder) were mixed into limestone cement mortars for obtaining in-bulk water-repellent mortars suitable for building protection and resistant to the degrading action of water. The influences of the admixtures on the hydration and structure of the designed mortars were investigated by SEM, TG–DSC, FT-IR, XRD, and isothermal calorimetry. The effectiveness of these agents against water action was evaluated by using techniques and methods such as mercury intrusion porosimetry, water absorption tests and contact angle measurements. Siloxane products conveyed good water-repellent effectiveness, without strongly influencing the setting and hydration of the binder, while the zinc stearates slowed down the hydration reactions.
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| 14. |
- Flansbjer, Mathias, et al.
(författare)
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Composite Behaviour of Textile Reinforced Reactive Powder Concrete Sandwich Façade Elements
- 2018
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Ingår i: International Journal of Concrete Structures and Materials. - : Springer Science and Business Media LLC. - 1976-0485 .- 2234-1315. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Within the EC funded project smart elements for sustainable building envelopes, carbon textile reinforcement was incorporated into reactive powder concrete, namely textile reinforced reactive powder concrete (TRRPC), to additionally improve the post-cracking behaviour of the cementitious matrix. This high-performance composite material was included as outer and inner façade panels in prefabricated and non-load bearing sandwich elements along with low density foamed concrete (FC) and glass fibre reinforced polymer continuous connecting devices. Experiments and finite element analysis (FEA) were applied to characterize the structural performance of the developed sandwich elements. The mechanical behaviour of the individual materials, components and large-scale elements were quantified. Four-point bending tests were performed on large-scale TRRPC-FC sandwich element beams to quantify the flexural capacity, level of composite action, resulting deformation, crack propagation and failure mechanisms. Optical measurements based on digital image correlation were taken simultaneously to enable a detailed analysis of the underlying composite action. The structural behaviour of the developed elements was found to be highly dependent on the stiffness and strength of the connectors to ensure composite action between the two TRRPC panels. As for the FEA, the applied modelling approach was found to accurately describe the stiffness of the sandwich elements at lower load levels, while describing the stiffness in a conservative manner after the occurrence of connector failure mechanisms. © 2018, The Author(s).
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| 15. |
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| 16. |
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| 17. |
- Flansbjer, Mathias, et al.
(författare)
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Structural Concept of Novel RPC Sandwich Façade Elements with GFRP Connectors
- 2016
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Ingår i: IABSE Congress Stockholm 2016. - : IABSE c/o ETH Hönggerberg. - 9783857481444 ; , s. 2164-2171
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Konferensbidrag (refereegranskat)abstract
- The SESBE research project aims to develop novel smart sandwich façade elements with high insulating capabilities while providing a reduced thickness in conjunction with superior mechanical and durability properties. The present paper mainly focuses on the verification of the mechanical performance of the glass fibre reinforced polymer (GFRP) connectors in the façade element composed of reactive powder concrete (RPC) panels with foam concrete insulation between them. Because of the reduced thickness of the large façade elements, the performance of the connectors is critical for the entire structural concept. A description of structural performance and results based on experimental methods and finite element (FE) analysis are presented.
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| 18. |
- Flansbjer, Mathias, et al.
(författare)
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Strutural performance of GFRP connectors in Composite sandwich facade elements
- 2016
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Ingår i: Journal of Facade Design and Engineering. - 2213-302X .- 2213-3038. ; 4:1-2, s. 35-52
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Tidskriftsartikel (refereegranskat)abstract
- A systematic testing and modelling program has been developed for the verification of the structural performance of facade sandwich elements to take structural aspects into consideration in the SESBE research project, focusing on the development of “smart” facade elements.The present paper mainly focuses on the verification of the mechanical performance of the glass fibre reinforced polymer (GFRP) connectors of the novel type of facade element composed of reactive powder concrete (RPC) panels with foam concrete insulation between them. Because of the reduced thickness of the large facade elements, the performance of the connectors is critical for the entire structural concept. The first series of the testing and modelling programme concerning connector performance are presented here. The results suggest that sufficient strength and ductility of the connectors can be ensured using GFRP in the proposed thin light-weight facade elements.
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| 19. |
- Grigoriadis, K., et al.
(författare)
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Improving the recycling rate of the construction industry
- 2019
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Ingår i: Sustainable Construction Materials and Technologies. - : International Committee of the SCMT conferences.
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Konferensbidrag (refereegranskat)abstract
- Construction and Demolition Waste (CDW) accounts for approximately 25-30% of all waste generated across Europe each year. However, Waste Framework Directive 2008/98/EC requires from all EU member states to achieve at least 70% re-use, recycling or other recovery of non-hazardous CDW by 2020. In response, the Horizon 2020 RE4 Project (REuse and REcycling of CDW materials and structures in energy efficient pREfabricated elements for building REfurbishment and construction) consortium was set up. Its main aims are to assess the quality of various CDW fractions (e.g. mineral aggregate, timber, plastics, silt & clay), improve the quality of mineral aggregates and develop different building elements/components which contain at least 65% of CDW. Innovative building concepts will also be developed in an effort to improve recycling rates of future buildings through the use of prefabrication and modular design. The developed products and technologies will be assessed in a number of test sites by building 2-storey demonstration houses.
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| 20. |
- Helsing, Elisabeth, et al.
(författare)
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Hydrofoberande medel i sprutbetong : Inverkan på egenskaper och beteendet vid sprutning
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det övergripande målet med projektet är att få fördjupade kunskaper och erfarenheter när det gäller användning av hydrofoberande medel som tillsätts betongmassan i sprutbetong med lågalkaliska bindemedel, med syfte att förbättra sprutbetongens beständighet och brukbarhet. Resultaten från detta projekt bidrar till ökad förståelse för praktiska möjligheter med och begränsningar för hydrofoberande medel som tillsätts betongmassan i sprutbetong, och därmed minskar behovet av kostsamma fältförsök, med ” trial and error”.En stor del av projektet har ägnats åt att studera inverkan av hydrofoberingsmedlen på egenskaperna i det tidiga stadiet, då de är avgörande för den praktiska tillämpningen. Därutöver har inverkan på egenskaper som hållfasthetsutveckling och vidhäftningshållfasthet mätts. Vilken hydrofobicitet som dessa medel ger betongen har också undersökts. Dessa provningar har främst gjorts på pasta, bruk eller betong som gjutits på konventionellt sätt, alltså inte på sprutbetong. Därutöver har provsprutning gjorts med en betong med ett av medlen samt en referens utan hydrofoberingsmedel för att kartlägga beteendet vid sprutning. På prover av den sprutade betongen har vidhäftningshållfastheten, hydrofobiciteten och kloridinträngningen bestämts.Två hydrofoberande medel, Sitren P 750 (E) och Silres BS 1001 (W) har använts, båda baserade på organosilikater. Medel E grundar sig på modifierad siloxan som är anbringad på silikastoft och medel W är en vattenbaserad emulsion av silan/siloxan. De flesta provningarna har utförts dels med ett rent Portlandcement (Degerhamns Anläggningscement från Cementa) och dels ett Portland-flygaskecement (Slite Anläggning FA från Cementa). Båda är sulfatresistenta och lågalkaliska. Provningar med och utan accelerator har utförts.Använda utan accelerator påverkade medel W bindetid och värmeutveckling i betydligt högre grad än medel E. Medel W hade en klart retarderande effekt. Denna effekt kunde dock i hög grad kompenseras genom tillsats av en accelerator. 28-dygnshållfastheten sänktes med båda hydrofoberingsmedlen, mest med medel W, men även i detta fall kompenserades denna effekt till viss del av acceleratorn. Acceleratorn hade inte samma avgörande effekt när medel E användes.Vid provning på gjuten betong var vidhäftningen bättre och mindre spretig (mindre standardavvikelse) med medel W än med medel E. Hydrofobiciteten hos blandningar med de båda medlen vara jämförbar.Provprutningen genomfördes med medel W och accelerator. Med hydrofoberingsmedel erhölls samma konsitens med mindre mängd vatten. Beteendet vid sprutning med medel W var lika bra som eller något bättre än utan. Hydrofoberingsmedlet påverkade inte sprutbetongens vidhäftning. Vattenabsorptionen hos sprutbetongen med hydrofoberingsmedel var c:a 30 % lägre än utan sådant medel, och motståndet mot kloridinträngning ungefär 40 % bättre.
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| 21. |
- Hesselgren, Lars, et al.
(författare)
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NuMo – New Urban Mobility : New urban infrastructure support for autonomous vehicles
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Foreword All transport systems have a certain capacity determined by its configurations. For cars the most efficient current form is constant speed driving, e.g. the motorway. Its capacity is limited by the time separation between vehicles. Any transport system that stops because of congestion or other causes by definition sees its capacity reduced to zero. Hence traffic jams are hugely disruptive. Public transport operates on a model inherited from the 19 th Century. Vehicles (buses, trams, railways, metros) run on a regular (timetabled) basis and stops at every station (bus stop). Since there is no pre-booking and the need of transport is hard to foresee, the vehicles are often almost empty, at other times hugely congested. The NuMo technology emerges from decades of work across the whole transportation industry. Autonomous electric vehicles (AEVs) equipped with vehicle-to-vehicle (V2V) communication can safely keep shorter distances. In practical terms this means that a platooned car system has the same capacity in one lane as a double-lane motorway. Automated intelligent controls ensure that the NuMo systems never stops, thus achieving the highest capacity. Instead of waiting for the mass deployment of fully automated vehicles, NuMo starts with dedicated networks that integrate tightly with existing infrastructure for step-wise smooth transition to fully automated transport system. NuMo includes an on-demand public transport system which only runs when it is needed. The system will take advantage of close-spacing possible with robot controls – vehicles can run close together and also use less road width by less wiggling. Equally importantly stations and access to the normal road network is arranged such that the traffic flow never stops. The urban impact can be imagined by understanding the impact of modern public transport systems currently under construction. Some of them are underground to avoid disrupting the street patterns. Some are elevated, some rely on physical separation at grade. One interesting option is to use tunnels underground or in water to further reduce disruption. Many cities are abandoning the traditional port infrastructure giving huge opportunities to again regard water as a connector rather than something to cross. The NuMo system uses all of those techniques and detailed design studies are under way for each of those options. NuMo will make an important contribution to environmental sustainability in many respects. Firstly, it will accelerate adoption of electric propulsion; secondly it will encourage vehicle sharing; and thirdly by only running when needed will save on unnecessary movements and finally its construction costs will be less than conventional systems. Sketches of NuMo networks are presented on places as diverse as Stockholm, Gothenburg and New York. Naturally the system will also be crucial in the development of new cities. This report is a summary of the studies performed within the project “New urban infrastructure support for autonomous vehicles” financed by Vinnova through the Strategic Innovation Program InfraSweden2030. The aim is to explore the infrastructure support to accelerate the introduction of autonomous electric vehicles for future mobility.
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| 22. |
- Kargol, M A, et al.
(författare)
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Properties and performance of silane : blended cement systems
- 2013
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Ingår i: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 46:9, s. 1429-1439
-
Tidskriftsartikel (refereegranskat)abstract
- The paper presents the results of a study dealing with the performance of water repellents on hardened blended cement pastes. Since on the European market Portland cement does not play the dominant role anymore and due to the new national and European policies concerning Greenhouse Gases and sustainability, cement manufacturers produce more and more blended cements (CEM II-CEM V). Nevertheless, the majority of experience concerning the efficacy of water repellents is gained from Portland cement; therefore knowledge in regard to the interactions of blended cement with water repellent agent is minimal. Two silane-based products were applied on 'fresh' and carbonated cement substrates containing limestone, fly ash, slag and trass, and were investigated in terms of their functionality. The evaluation of the treatments' performance and effectiveness were assessed using various laboratory measurements. Hydrophobicity, water absorption, colour changes and the penetration depth of silanes into the substrate were evaluated before and after artificial aging experiments. Moreover, the outdoor weathering test was performed to shed light on treated surface appearance in a 'real' outdoor environment. The results showed that surface wettability was independent on water ingress or colour variations, especially for cement specimens artificially aged by accelerated carbonation. Cement pastes containing slag and trass seemed to more distinctly affect the water repellents' surface performance.
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| 23. |
- Lundgren, Monica, et al.
(författare)
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Exposure experiments in sulfate containing solution, including exposure at low temperature
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes results of an investigation on the sulfate resistance of dual blended binder of mortar and concrete specimens over a period of 1 year. The focus is on showing the importance of the chemistry of the components when discussing sulfate resistance and the relation of that to the hydrate phase assemblage. Moreover the importance of the test method for evaluations is pointed out.
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| 24. |
- Lundgren, Monica, et al.
(författare)
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Optimizing blended binders with slag or fly ash for improved sulfate resistance
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The report presents an investigation of the role of the sulfate balance in blended binders with slag (ground granulated blast furnace type, GGBS) or fly ash (low calcium type) in achieving improved sulfate resistance (SR) when using non-SR CEM I. The investigation involved experiments with sulfate-doped vs. undoped blended binders, pastes and mortars with and without exposure to sulfate attack, which was induced by immersion in Na2SO4 solution using a laboratory method. The results reveal the benefit of a sulfate level adjustment to promote improved behaviour during sulfate attack: doped blends yielded lower expansion during sulfate attack and reduced internal damage compared to undoped alternatives. Sulfate-doping increased the potential of slag and fly ash to mitigate sulfate attack with non-SR cement.
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| 25. |
- Lundgren, Monica, et al.
(författare)
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State-of-the-Art Report on: Material Type, Requirements and Durability aspects of Sprayed Concrete in Tunnels
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The report summarizes a state-of-the-art for sprayed concrete applied for ground support in tunnel environments, in Sweden and several European countries, with focus on the components, the mix design and the guidelines and specifications. It focuses also on the addition of supplementary cementitious materials (SCM), where the use, the common practice and the long-term experience vary from country to country. The report presents numerous examples of applications in Sweden and seven other European countries. It also gives an overview about the possible exposure risks and summarizes the relevant durability issues. Along with specifications in international standards and guidelines it also reviews the national requirements in Sweden, Norway, Finland, Austria, France, Germany and Switzerland.
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| 26. |
- Malaga, Katarina, et al.
(författare)
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Relevance of hydrophobic and oleophobic properties of antigraffiti systems on their cleaning efficiency on concrete and stone surfaces
- 2013
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Ingår i: Journal of materials in civil engineering. - 0899-1561 .- 1943-5533. ; 25:6, s. 755-762
-
Tidskriftsartikel (refereegranskat)abstract
- The problem of graffiti is not entirely restricted to urban areas, but also appears frequently in rural communities and along traffic infrastructure. Besides its aesthetic and societal effects, graffiti cause considerable removal costs and subsequent costs for repairing damages caused by improper graffiti removal. Over the last two decades, strategies have been developed to combat graffiti in the built environment, including the development of protective measures in the form of antigraffiti systems (AGSs). Antigraffiti systems promise to be affordable and easily applicable for a wide range of substrates, and many products have already been on the market for many years. In practice, however, successful application of AGS and removal of graffiti depend on many factors in which the type of coating and condition of the substrate play critical roles. The optimal environmental goal is to use AGS without any cleaning chemicals except for pure water. Available studies on the behavior of the same AGS on various substrates can show completely different results concerning the cleaning efficacy and the durability of the AGS under different climatic conditions. The question of which properties of an AGS are most essential for its efficiency has still not been fully investigated. The goal of this study was to investigate cleaning efficacy in conjunction with hydrophobic and oleophobic properties of the AGS on different substrates. The results showed that hydrophobicity and oleophobicity are important for dense substrates but have a low influence on porous substrates. In this case, cleaning efficiency is majorly determined by the physical properties of the substrates.
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| 27. |
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| 28. |
- Meng, Birgit, et al.
(författare)
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Performance of a new anti-graffiti agent used for immovable cultural heritage objects
- 2014
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Ingår i: International Journal of Architectural Heritage. - : Informa UK Limited. - 1558-3058 .- 1558-3066. ; 8:6, s. 820-834
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Tidskriftsartikel (refereegranskat)abstract
- Cultural Heritage objects are in many cases invaluable and irrecoverable, therefore their protection is a major goal. One threat arises by intentionally defacing such objects with graffiti. One possibility to face the imminent threat is the application of a surface protection in form of anti-graffiti systems (AGS). However, the knowledge about the performance and durability of AGS on substrates used for historical buildings is still fragmented. The goal of the present study was to investigate the performance of a newly developed anti-graffiti agent in comparison to a selection of commercial anti-graffiti agents on different substrates that were used for historical buildings. Four commercial anti-graffiti agents with different chemical formulations were selected and tested with the new agent on different stone and brick substrates. The results showed clearly that AGS based on dense, water-vapor impermeable coatings are not suitable to porous substrates such as sandstone, brick, or porous limestone due to their impairment of the hygric properties and the visual appearance of a substrate. The new agent could not completely reach the cleaning efficacy of the dense coatings but exhibited a much lower impact on the properties of the substrate and was therefore better compatible to historical surfaces.
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| 29. |
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| 30. |
- Miccoli, Lorenzo, et al.
(författare)
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Experimental testing and finite element modelling of earth block masonry
- 2015
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 104, s. 80-94
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Tidskriftsartikel (refereegranskat)abstract
- The current paper focuses on the determination of reliable numerical models of earth block masonry wallettes under different loading conditions. Uniaxial compression and diagonal compression tests were performed. Experimental behaviour was modelled with a non-linear model able to describe the cracking behaviour. The simplified approach based on macro-modelling shows a satisfactory accuracy and low computational costs. The results reproducing the uniaxial compression are in good correspondence with the post-elastic behaviour observed in the experimental campaign. The micro-modelling approach adopted to reproduce the shear behaviour, even with high computational cost, represents a suitable tool to predict the masonry collapse mechanism.
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| 31. |
- Miccoli, Lorenzo, et al.
(författare)
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In-plane behaviour of rammed earth under cyclic loading : Experimental testing and finite element modelling
- 2016
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 125, s. 144-152
-
Tidskriftsartikel (refereegranskat)abstract
- The purpose of this paper is to numerically simulate the in-plane behaviour of rammed earth walls under cyclic shear-compression tests. The experimental testing allowed obtaining the maximum horizontal loads, the displacement capacity and the level of non-linear behaviour of the respective load-displacement relationships as well as the failure modes. The calibration of the numerical model (finite element method) was carried out based on the experimental results. Within this framework, a micro-modelling approach was considered. The behaviour of the rammed earth material was simulated using a total strain rotating crack model. A Mohr-Coulomb failure criterion was used to reproduce the behaviour of the interfaces between the layers. Although the numerical results achieved a satisfactory agreement with the experimental results a sensitivity analysis of the parameters involved was performed. The sensitivity analysis aimed at determining which parameters of the model have a significant impact in the model's results. As expected the sensitivity analysis pointed out that the sliding failure occurrence is mainly influenced by two parameters of the interface elements: the interface tensile strength fit and the friction angle φ. Moreover the cohesion c and the layers thickness showed a limited effect on the shear behaviour. It should be noted that the results mentioned above are related to the cases where a significant level of vertical compressive stress σ is employed.
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| 32. |
- Miccoli, L., et al.
(författare)
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In-plane shear behaviour of earthen materials panels strengthened with polyester fabric strips
- 2016
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Ingår i: Structural Analysis of Historical Constructions. - : CRC Press/Balkema. - 9781138029514 ; , s. 1099-1105
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Konferensbidrag (refereegranskat)abstract
- An experimental investigation was carried out to study the in-plane shear behaviour of earthen material panels strengthened with polyester fabric strips. Strengthened panels were developed to exploit the strength potential of earthen materials and to solve its lack of tensile strength, significantly improving not only strength but also ductility. Three earthen materials were considered: cob, earth block masonry (EBM) and rammed earth (RE). As first approach the strengthening configuration, based on different adhesive materials, was tested only for cob panels. As part of the study the results of a big testing campaign of unstrengthened panels were considered. Seven strengthened panels were tested in diagonal compression/shear.A unique reinforcement orientation was used. The results of these tests are presented in this paper, and include the load-displacement behaviours, crack patterns, failure modes. The results showed that the reinforcement was the most effective in EBM panels, with increase in strength and ductility observed. In RE and cob panels the reinforcement did not likely contribute significantly to the shear resistance, due to a lack of embedment length of the strips. Instead, in EBM it was likely that the vertical reinforcement acted in tension to restrain shear induced dilation and to restrain sliding.
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| 33. |
- Miccoli, L., et al.
(författare)
-
Mechanical behaviour of earthen materials. : A comparison between earth block masonry, rammed earth and cob
- 2014
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 61, s. 327-339
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Tidskriftsartikel (refereegranskat)abstract
- Earth represents one of the oldest construction materials, which is still utilised both in developed and in developing countries. In this paper a comparison of the mechanical performance of structural elements built in three basic techniques, earth block (adobe) masonry, rammed earth and cob, is presented. In order to gain better knowledge on the structural behaviour under static loads an extensive compression and diagonal compression (shear) test campaign was performed. First compression results showed brittle mechanical behaviour in the case of earth block masonry and rammed earth elements, whereas cob exhibited a very different stress-strain pattern: cob can deform beyond the elastic range with a gradual drop in capacity. Despite its low compressive strength, cob thus presents a relatively good performance within the earthen material range as far as shear behaviour is concerned. The data here reported represents a base for a further investigation on the dynamic behaviour of the three materials considered. The study was carried out within the framework of the project NIKER funded by the European Commission dealing with improving immovable Cultural Heritage assets against the risk of earthquakes.
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| 34. |
- Miccoli, Lorenzo, et al.
(författare)
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Numerical modelling of UHPC and TRC sandwich elements for building envelopes
- 2015
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Ingår i: IABSE Conference 2015. - Zurich, Switzerland : IABSE. - 9781510820029 ; , s. 195-203
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Konferensbidrag (refereegranskat)abstract
- In this paper a modelling approach is presented to reproduce the mechanical behaviour of sandwich panels via finite element analysis. Two types of panels were investigated in this scope of work. The first sandwich element was a textile reinforced concrete (TRC) panel with cellular lightweight concrete insulation and the second configuration was an ultra-high performances concrete (UHPC) panel with aerated autoclaved concrete insulation. The goal was to obtain a reliable numerical strategy that represents a reasonable compromise in terms of sufficient accuracy of the element characteristics and the computational costs. The results show the possibility of describing the composite action in a full sandwich panel. The achieved modelling approach will later be used for the optimization of TRC and UHPC panels in terms of minimizing the thickness, identifying the number and location of connectors, as well as evaluating varying anchorage systems.
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| 35. |
- Miccoli, Lorenzo, et al.
(författare)
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Rammed earth walls strengthened with polyester fabric strips : Experimental analysis under in-plane cyclic loading
- 2017
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 149, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- This study analyses the mechanical behaviour under pseudo-dynamic loading of structural elements built in rammed earth and strengthened with polyester fabric strips. This strengthening technique was developed to exploit the strength potential of rammed earth and to solve its lack of tensile strength. For this reason, in-plane cyclic tests were carried out to investigate the shear behaviour of unstrengthened and strengthened walls. The strengthening technique requires low-tech equipment and workmanship, uses readily available, not expensive and industrially standardised materials. The experimental results were analysed in terms of stiffness degradation, energy dissipation capacity and equivalent viscous damping. Although the unstrengthened and strengthened walls confirmed a limited ductile behaviour, the findings confirm that the strengthening contributes to limit the spread of the diagonal cracks and provide an increase of strength in terms of horizontal load and displacement capacity.
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| 36. |
- Miccoli, Lorenzo, et al.
(författare)
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Static behavior of cob : Experimental testing and finite-element modeling
- 2019
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Ingår i: Journal of materials in civil engineering. - 0899-1561 .- 1943-5533. ; 31:4
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to implement a numerical model to reproduce the nonlinear behavior of cob walls under shear loading. Axial compression, pull-off, and diagonal compression tests were carried out to derive the mechanical parameters. In addition, the stressstrain relationships, the nonlinear behavior, and the failure modes were defined. The experimental results were then used to calibrate a finiteelement model. The material behavior was simulated through a macromodeling approach adopting the total strain rotating crack model. A sensitivity analysis was conducted to assess the effects of varying the parameters with higher uncertainty on the structural behavior. The numerical model achieved good correspondence with the experimental results in terms of simulation of the shear stress-shear strain relationship and of damage pattern.
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| 37. |
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| 38. |
- Miccoli, L., et al.
(författare)
-
Static behaviour of rammed earth : experimental testing and finite element modelling
- 2015
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Ingår i: Materials and Structures. - : Kluwer Academic Publishers. - 1359-5997 .- 1871-6873. ; 48:10, s. 3443-3456
-
Tidskriftsartikel (refereegranskat)abstract
- The paper presents an experimental program aiming at assessing the mechanical performance of rammed earth walls, namely under compression and shear loading. Axial compression and diagonal compression tests were carried out for this purpose, which allowed determining important mechanical parameters, such as compressive strength, Young’s modulus, Poisson’s ratio, shear strength and shear modulus. Furthermore, it allowed assessing the level of non-linear behaviour of the respective stress–strain relationships as well as the failure modes. The experimental results were then used in the calibration of numerical models (finite element method) for simulating the non-linear behaviour of rammed earth under shear loading. Both macro- and micro modelling approaches were considered for this purpose. The total strain rotating crack model was used to simulate the behaviour of the rammed earth material, while the Mohr–Coulomb failure criterion was used to simulate the behaviour of interfaces between layers. In general, the numerical models achieved good agreement with the experimental results, but uncertainties related to the definition of the input parameters required to perform a sensitivity analysis. The compressive strength, the Poisson’s ratio, the tensile strength and the tensile fracture energy revealed to be the most important parameters in the analyses.
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| 39. |
- Mir, Zahid Mohammad, et al.
(författare)
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Numerical and Experimental Analysis of Self-Protection in Reinforced Concrete due to Application of Mg–Al–NO2 Layered Double Hydroxides
- 2020
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Ingår i: Advanced Engineering Materials. - : Wiley-VCH Verlag. - 1438-1656 .- 1527-2648.
-
Tidskriftsartikel (refereegranskat)abstract
- Concrete possesses an intrinsic chloride binding capacity. Chloride ions from the environment bind with the hydrated cementitious phases in the form of bound chlorides. The contribution of chemically bound chlorides toward increasing the service life of concrete structures is vital as they help in slowing down the chloride diffusion in the concrete thereby delaying reinforcement depassivation. The authors attempt to increase the chloride binding capacity of concrete by adding a small amount of Mg–Al–NO2 layered double hydroxides (LDHs) with the objective to delay reinforcement corrosion and by this to considerably extend the service life of concrete structures situated in harsh environments. This study presents numerical and experimental analysis of the action of LDH in concrete. Formation factor is used to determine the effective chloride diffusion coefficient. In addition, the chloride binding isotherms together with Poisson–Nernst–Planck equations are used to model the chloride ingress. A comparable chloride binding is observed for concrete with and without Mg–Al–NO2, depicting only a slight chloride uptake by Mg–Al–NO2. Further investigations are conducted to understand this behavior by studying the stability and chloride entrapping capacity Mg–Al–NO2 in concrete. © 2020 The Authors.
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| 40. |
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| 41. |
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| 42. |
- Mueller, Urs, et al.
(författare)
-
Development of a lime based grout for cracks repair in earthen constructions
- 2016
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 110, s. 323-332
-
Tidskriftsartikel (refereegranskat)abstract
- The study presents the results from the development of a grouting material based on hydrated lime with addition of pozzolana, which is referred to as hydraulic lime, suitable for the repair of cracks in a variety of earthen building techniques. The goal was to develop a material also compatible with earthen structures exposed to dynamic loads. The grouting mortar was designed to be adaptable in strength properties and at the same time to have sufficient robustness for preparation and use on the construction site. Results showed a satisfactory performance of the grout concerning fresh and hardened mortar properties as well as injectability.
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| 43. |
- Mueller, Urs, et al.
(författare)
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Development of pore structure and hydrate phases of binder pastes blended with slag, fly ash and metakaolin – A comparison
- 2015
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Ingår i: ICCC 2015 Beijing.
-
Konferensbidrag (refereegranskat)abstract
- Blended binder systems in concrete have been in use for many years. However, over the recent discussions on the sustainability of cement and concrete the topic became of paramount importance for the construction industry. In Sweden blended binder systems in concrete were applied fairly recently and supplementary cementitious materials (SCM) were not used largely before. In Sweden over the last 30 years engineering structures were built, with exceptions, with a low alkali, sulfate resistant Portland cement due to domestic requirements. Therefore, in context to blended binder systems durability is a major point being discussed. Most interest lays in the resistance towards frost, carbonation and chloride penetration and the experience with blended systems was limited. It is therefore the goal of this study to investigate blended binder systems over a longer hydration period of up to two years in context to durability. The results presented here will focus on the porosity and hydrate phase development within the first 90 days of hydration. In this study in total 9 different binder blends were studied. The blends included different replacement levels with granulated blast furnace slag from a Swedish producer, fly ash from a Danish power plant and commercially available metakaolin. The matrix included also one set of factory-blended cements (with interground fly ash and slag). The pore structure was investigated by mercury intrusion porosimetry (MIP), phase development by powder x-ray diffraction (XRD). The results are based on the evaluation of binder paste samples. Compared to a reference series consisting of a CEM I the slag containing series showed a continuous decrease of the total pore volume with increasing slag content over 90 days of hydration. The phase development showed a constant increase in monosulfate and hydrotalcite. The amount of these phases increased with increasing slag content. Notable was consumption of C4AF, which increased with the amount of slag and a decrease of C2S reaction. Compared to the reference Portland cement paste the fly ash containing pastes showed increased total pore volumes when the fly ash was just added. For the cement paste with interground fly ash the porosity development was the same as for the reference paste. The phase development for these series showed up to 28 days of hydration formation of ettringite, hemicarbonate and monocarbonate. After 91 days monosulfate was dominating and the amount of hemicarbonate was decreasing. The paste series with 15 % metakaolin showed a strong decrease in total pore volume compared to the reference series within 2 days. Afterwards the pore volume almost leveled to a constant value. The hydration phases included in the beginning large amounts of monosulfate, ettringite and hemicarbonate but changed after 91 days in favor to ettringite and monocarbonate. The metakaolin blend showed the lowest amounts of portlandite in all series, indicating a strong pozzolanic reactivity. The different hydrate phases, in particular AFm phases can help to explain a different behavior towards, e.g. chloride binding. The pore structure development has a large impact not only on strength development but also for ion and moisture transport as well as for carbonation in all series.
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| 44. |
- Mueller, Urs, et al.
(författare)
-
Eigenschaften industrieller lehmbauprodukte für den mauerwerksbau und verhalten von lehmsteinmauerwerk
- 2012
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Ingår i: Masonry. - : Wiley. - 1432-3427 .- 1437-1022. ; 16:1, s. 17-28
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Properties of industrially produced earthen building products for masonry and behaviour of earth block masonry. The contribution gives an overview of the properties of industrially produced earthen building products for masonry. In the meantime the quality of the industrial production of this group of building materials reached a level similar to that of other products for construction. Earth plasters exist as plasters for universal, one or multi layer applications or as lower, upper or finish plasters. Earth blocks are provided in different sizes and with different perforations. The mechanical properties of different earth block types are signified by compressive strength of up to 11 N/mm2 but are typically in a range between 2 and 5 N/mm2. A critical point is the correlation of the strength of earthen materials with their moisture content. Results from earth blocks showed that in a relative humidity window between 40 and 70 % rh the compressive strength of earth blocks is fairly constant. Masonry made from earth block and earth mortar exhibited compressive strength and elastic modules similar to masonry made with aerated autoclaved concrete blocks. The shear strength of earth block masonry, however, is fairly low, due to the weak bond between earth block and earth mortar.
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| 45. |
- Mueller, Urs, et al.
(författare)
-
Hydration of concrete binders blended with ground granulated blast furnace slag, fly ash and metakaolin
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report describes a study on the effects of ground granulated blast furnace slag, low calcium fly ash and metakaolin on the hydration behavior of different binder pastes blended with these SCM. The study investigated early heat development, phase assemblages at different ages, strength gain, changes in porosity and pore sizes, pore water OH-concentration, development of the microstructure and the micro chemistry of the binder pastes.It was shown that all SCM impact the pore size distribution of pastes of different ages. Compared to a reference paste without SCM, SCM containing pastes shift their pore size range to smaller sizes, the more SCM the pastes contain. The total porosity depends on the type of SCM. With slag, there was a tendency to decrease the total porosity with increasing SCM content. With fly ash, total porosity was increased with increasing fly ash content. The strength development of slag and fly ash containing mortars is under that of a Portland cement reference mortar within the first 28 days. However, after 28 d strength gain, in particular with fly ash is considerable compared to the reference. With metakaolin already at early ages a strong increase in strength was observed. After that, the strength development was parallel the one of the reference mortar. Aluminum containing SCM contribute to the formation of AFm phases. AFm phases increase the chloride binding in seawater or deicing salt exposed concretes. In particular metakaolin and fly ash contribute, due to their high alumina content, to the formation of AFm phases but also increase the aluminum content in the C-S-H phases.
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| 46. |
- Mueller, Urs, et al.
(författare)
-
Influence of hydrophobicity and oleophobicity on cleaning graffiti on concrete panels and natural stones
- 2012
-
Ingår i: Concrete Repair, Rehabilitation and Retrofitting III (ICCRRR). - : TAYLOR and FRANCIS GROUP, LONDON, UK. ; , s. 269-275
-
Konferensbidrag (refereegranskat)abstract
- Anti-Graffiti Systems (AGS) are meant to make the cleaning process more efficient by inserting a layer between the paint and the substrate. This layer can have a low surface energy thus make it difficult for the paint to stick to the substrate or it may be easily removed together with the paint. This paper is presenting results from a study of how hydrophobicity and oleophobicity influence the cleaning efficiency of graffiti paints from concrete and natural stones. The results demonstrated that high hydrophobicity and high oleophobicity are not guaranteeing satisfying cleaning effects. The physical properties of a substrate in combination with the characteristics of the AGS layer decide about the cleaning effect.
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| 47. |
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| 48. |
- Mueller, Urs
(författare)
-
Mineralische Baustoffe : Untersuchen, Bewerten und Konservieren
- 2021. - 1
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Um Denkmäler zu bewahren und Altbauten für eine zeitgemäße Nutzung instand zu setzen, sind Lösungen notwendig, die den Eigenschaften und dem Erhaltungszustand der Gebäude angepasst sind. Dazu ist ein Grundwissen über historische Baustoffe erforderlich. Reparaturmaterialien interagieren physikalisch und chemisch mit dem Bestand. Falsche Reparaturversuche können Schäden verschlimmern oder neue Schäden hervorrufen. Dieses Buch ist eine Baustoffkunde der seit Jahrtausenden gebräuchlichen Materialien Lehm, Kalk, Gips, Naturstein und Ziegel. Behandelt werden außerdem Zementmörtel und historische Betone sowie unterschiedliche Farben und Pigmente. Ein Kapitel ist dem Asbest gewidmet. Der Autor beschreibt die Geschichte der Entstehung oder Herstellung dieser Baustoffe, ihre stoffliche Zusammensetzung und die Materialeigenschaften. Ein wesentlicher Teil des Buches befasst sich mit naturwissenschaftlichen Grundlagen und Analysemethoden, mit denen Materialzusammensetzungen bestimmt und Schadensursachen aufgeklärt werden können. Dieses Grundwissen benötigen Planer, damit sie baustoffkundliche Untersuchungen gezielt beauftragen und fundierte Entscheidungen für Maßnahmen zum Schutz, zur Konservierung oder zur Instandsetzung treffen können. Das Buch ist Teil der Reihe »Erhalten historisch bedeutsamer Bauwerke - Empfehlungen für die Praxis«. Diese Buchreihe stellt in thematisch abgegrenzten Einzelbänden konzeptionell-entwurfliche und bautechnisch-konstruktive Methoden für einen behutsamen Umgang mit historischer Bausubstanz vor, bei dem Eingriffe auf das wirklich Notwendige beschränkt werden. Sie gründet auf einer gleichnamigen, vor genau 20 Jahren von Fritz Wenzel und Joachim Kleinmanns herausgegebenen Publikationsreihe, in der die Ergebnisse des Sonderforschungsbereichs 315 »Erhalten historisch bedeutsamer Bauwerke - Baugefüge, Konstruktionen, Werkstoffe« veröffentlicht wurden.
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| 49. |
- Mueller, Urs, et al.
(författare)
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Novel techniques for studying damage mechanisms of cementitious matrices affected by sulphate attack
- 2012
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Ingår i: fib symposium Concrete Structures for Sustainable Community. ; , s. 267-270
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Konferensbidrag (refereegranskat)abstract
- In the presented study novel methods were applied to analyse the changes of the cement phase composition due to sulphate attack. The analytical methods were based on spatial x-ray diffraction using synchrotron radiation and incoherent white x-ray radiation. The spatial resolution of the methods is ca. 10 μm and 400 μm, respectively. The specimens for phase analysis consisted of thick sections of sulphate exposed cement paste specimen. Different cement pastes showed a clear evolution in the sulphate and phase distribution. Phase analytical data was compared to chemical information acquired by SEM-EDX analysis.
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| 50. |
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