| 1. |
- Helsing, Elisabeth, et al.
(författare)
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Kortversion av SVU-rapport 2022:5 ”Klimatförbättrad betong för dricksvattenanläggningar”
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This RISE report is a short version of SVU report 2022:5 “Klimatförbättrad betong för dricksvattenanläggningar” (Low carbon concrete for drinking water infrastructure). The purpose of the project was to clarify if the carbon footprint of concrete for drinking water infrastructure can be lowered by replacing Portland cement with supplementary cementitious materials (SCM) accepted for use in concrete without influencing the quality of the drinking water negatively with regard to trace substances and PAH. In addition to reviewing the literature, leaching tests and LCA analyses were conducted on thirteen concretes mixes with varying binder compositions. The results show that it is possible to replace up to 50 % of the cement with the SCMs, ground granulated blast furnace slag (GGBS), silica fume and fly ash. All this may be GGBS and up to 35 % fly ash may be used. This is valid under condition that a drinking water facility which in its entirety is new drinking goes through a tuning period of some days up to a week during which the water quality is monitored before water is delivered to clients. Leaching of some substances is somewhat increased and others are decreased by the replacement of the cement, however the changes are so small that the content in the drinking water in a real facility is only marginally influenced. Which type of binder to use should be decided based on other these materials influence on other concrete properties, for instance on the strength development. The decrease of the carbon footprint is roughly proportional to the cement replacement ratio.
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| 2. |
- Helsing, Elisabeth, et al.
(författare)
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Vidareutveckling av provningsmetod för klotterskyddsprodukter för betongytor
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Further development of a test method for anti-graffiti products for concrete surfaces Modified test methods for the performance of anti-graffiti coatings are presented in this report. As a base a test method applied in Sweden since is used which involves outdoor exposure of concrete slabs on which the coatings are applied followed by application of the graffiti and cleaning. The modifications are based on a review of methods existing in other countries, discussions with producers of anti-graffiti coatings and a test program carried out at RISE in Borås. The tests were carried out with two sacrificial coatings and some permanent coatings. In the latter case the graffiti is applied and cleaned ten times. In the existing method, the outdoor exposure is said to be three months. However, it was found that when this exposure takes place, in winter or in summer, greatly influenced the protective capability of the coating. In this project the influence of three different exposures were investigated; three month summer exposure, three month winter exposure and twelve month exposure. The test showed that the three-month summer exposure and the twelve-month exposure gave comparable results. Hence prolonging the exposure period is not necessary. However, very deviating results were obtained after the three-month winter exposure. The evaluation of the protective capability is started with a visual inspection against certain specified assessment criteria on remaining stains and visible marks of graffiti. If the coating met the assessment criteria for the visual inspection, assessment criteria on colour changes measured with a colour measuring device shall also be met. Separate assessment criteria for measured colour changes are used for sacrificial and for permanent anti-graffiti coatings. For a sacrificial coating, the assessment criterium is given in relation to the original concrete surface, while for a permanent coating the assessment criterium is formulated in relation to the exposed surface. It was found that the performance requirement on changes in gloss was irrelevant. In the revised method the selection of colour types and water temperature and pressure used in pressure washing has been modified to be consistent with praxis. The drying between cycles including application of graffiti and cleaning was shortened. The method is divided into two methods; one for sacrificial anti-graffiti coatings and one for permanent anti-graffiti coatings that does not require the use of chemical compounds. The latter method is not applicable to permanent anti-graffiti coatings which need the help of chemical products to give satisfactory cleaning.
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| 3. |
- Malaga, Katarina, et al.
(författare)
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Kartläggning av befintlig provningsverksamhet för cement och betong i Sverige och bedömning av provningsbehov vid introduktion av nya cement
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten presenterar resultat från projektet ‘Kartläggning av befintlig provnings-verksamhet för cement och betong i Sverige och bedömning av provningsbehov vid introduktion av nya cement’. Mot bakgrund av en minskad eller stoppad produktion av cement vid Cementas fabrik i Slite gav Regeringen Verket för innovationssystem (VINNOVA) den 3 november 2021 i uppdrag att kartlägga befintlig provningsverksamhet för cement och betong (N2021/02773) som finns tillgänglig för svenska aktörer och att föreslå åtgärder som kan skapa förutsättningar för en samordning vid en kraftigt ökad efterfrågan på denna verksamhet. Denna rapport behandlar hur provningsbehovet kan komma att utvecklas vid stopp i den svenska cementproduktionen i Slite vilket resulterar i ett behov av introduktion av stora volymer av ett eller flera nya cement under kort tid. Denna händelse benämns i rapporten förenklat som “cementkris”. Rapporten pekar på några förutsättningar som bör gälla för att ett cementbyte skall kunna genomföras rimligt kontrollerat. I rapporten görs det inte någon bedömning av hur byggbranschen eller samhället i stort skulle påverkas av en cementkris. Det görs inte heller någon analys av vem som tillser att produktions-bortfallet från Slite ersätts med annat cement eller varifrån detta cement kan komma. För en bedömning av provningsbehovet av betong har detta inte någon avgörande betydelse. Ett nytt cement från Kina kräver för betongtillverkaren lika mycket provning som ett nytt cement från närområdet i Europa eller för den delen Sverige. Förutsatt att cementet i sig är CE-märkt och uppfyller svenska krav.Den huvudsakliga slutsatsen är att: Under förutsättning att inte avkall får göras på de krav som ställs på cement och betong i Sverige idag krävs det att nu använda och nya cement finns tillgängliga parallellt under en övergångsperiod på minst två och ett halvt år. Detta gäller främst betong till anläggningskonstruktioner och infrastrukturprojekt där kraven på kvalitetssäkring via provning på ackrediterade laboratorier är hög. På grund av ökat provningsbehov går det inte att genomföra ett omfattande byte av cement på ett stort antal betongfabriker under kort tid utan betydande störningar och stopp i betongleveranser till svenska byggarbetsplatser, om inte nu använda och nya cement finns tillgängliga parallellt. Inom husbyggnadsområdet är behoven av provning på ackrediterade laboratorier lägre. Hur snabbt och smidigt ett byte av cement kan göras för husbyggnadsbetong avgörs i stället av möjligheterna att utföra nödvändiga interna provningar och intrimningar på fabrikerna.Om nu använda och nya cement till anläggningsbyggandet finns tillgängliga parallellt under minst två och ett halvt år är bedömningen att nödvändig ökning av provnings-kapacitet hinner byggas upp samtidigt som ett byte från nu använda till nya cement kan göras på ett rimligt kontrollerat sätt med avseende på behovet av extern provning. Detta förutsätter emellertid att samtliga nya cement är CE-märkta och uppfyller svenska krav samt en samordning av provningskapaciteten inom vissa kritiska provnings-områden. För att öka provningskapaciteten på nationell nivå inom kritiska provnings-områden krävs en noggrann planering av hur en sådan utökning skall genomföras (lokaler, utrustning, kompetens, vem som skall vara huvudman) och vem som skall bekosta en sådan ökning av provningskapaciteten.
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| 4. |
- Mueller, Urs, et al.
(författare)
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Potential for use of activated clays in concrete in Sweden – Roadmap
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Swedish construction industry is generating a save and affordable built environment for transport, work and living but it is faced with a huge challenge: drastic reduction of greenhouse gases and an increase of circularity in their production cycles. One material, which has inherently embodied CO2, is limestone, which is needed for the production of Portland cement, the essential ingredient in concrete. The CO2 emission during cement production can be drastically compensated by so called supplementary cementitious materials (SCM), which replace cement components causing CO2 emissions. SCM can be used by incorporating them into Portland cement or can be used directly by mixing into concrete. However, traditionally used SCM such as ground granulated blast furnace slag or fly ash are only available in limited amounts in Sweden, not matching the domestic cement production. An alternative to those more traditional SCM is activated or calcined clay, which reacts similar to blast furnace slag or fly ash. Calcined clay is created from natural clays by heating up to 700 ° - 800 °C, where it become very reactive. In this roadmap the state-of-the-art about activated clays is shown from a Swedish perspective. It also shows challenges and needs that have been formulated for a future implementation of activated clays as a component of low carbon concrete.
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| 5. |
- Oliva Rivera, Alexander, et al.
(författare)
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Accelerated Carbonation of Binders Containing SCM at High CO2 Concentration
- 2023
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Ingår i: Nordic Concrete Research. - : Nordic Concrete Federation. - 0800-6377 .- 2545-2819. ; 69:2, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Accelerated carbonation of recycled concrete aggregates (RCA) could be an efficient way to reduce the carbon footprint. High CO2-concentration under optimal relative humidity could accelerate the CO2 binding capacity of the hydrated cement paste in the RCA. The latter is the topic of this paper. The study looks into the forced carbonation of crushed cement pastes as a basis to understand the CO2 uptake in relation to various binders containing supplementary cementitious materials (SCM) such as fly ash (FA) and ground granulated blast furnace slag (GGBS). Samples include three cement pastes: ordinary Portland cement, substitution rate of 30 % FA and 50 % GGBS respectively at a water/binder ratio of 0.45. All binders were graded to 0/2, 2/4 and 4/8 mm fraction sizes and preconditioned before exposed to CO2 concentration of 10 % under controlled temperature at 20 C-degrees and 65 % RH. All tested binders presented a high CO2 uptake within the first hours of exposure with clear differences concerning the fraction sizes and the composition. The phase content before and after carbonation was observed by X-ray diffraction and the portlandite and calcite were quantified by thermogravimetric analyses and their derivative curves for fraction size 4/8 mm.
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| 6. |
- Oliva Rivera, Alexander, et al.
(författare)
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Potential of CO2-Storage in Recycled Concrete Aggregates by Accelerated Carbonation
- 2023
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Ingår i: SynerCrete 2023: International RILEM Conference on Synergising Expertise towards Sustainability and Robustness of Cement-based Materials and Concrete Structures. - : Springer. - 9783031331862 - 9783031331879 ; , s. 604-615
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To reduce the carbon footprint of cementitious materials and resource extraction intensity of concrete industry (natural gravel or crushed rock), usage of recycled concrete aggregate (RCA) in concrete and as a CO2-sink by accelerated carbonation is widely investigated. Implementation of this technology will not only reduce the climate impact, but also improve the performance of the RCA creating a truly circular material. At first, some locally available recycled concrete was crushed in different fractions and characterized. To quantify the adhered mortar/aggregate content ratio on the as-received RCA, an image analysis method (IAM) was introduced. The analysis revealed that the adhered mortar accounts for around 40% of the RCA independently on the fraction. The results of IAM of as-received RCA were used to evaluate its remaining potential of CO2-storage. The effect of accelerated carbonation on the quality of RCA was evaluated by means of water absorption. The carbonation was determined by means of thermogravimetric analyses (TGA) and its derivative curve (DTG) resulting in similar CO2-storage for coarse fractions 4/8 mm and 8/16 mm under the accelerated carbonation conditions.
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| 7. |
- Sadagopan, Madumita, 1987-, et al.
(författare)
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Effects of Slag Addition and Mechanical Pre-Processing on the Properties of Recycled Concrete in Terms of Compressive Strength and Workability
- 2021
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Ingår i: Nordic Concrete Research. - : Walter de Gruyter GmbH. - 0800-6377 .- 2545-2819. ; 64:1, s. 11-29
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Tidskriftsartikel (refereegranskat)abstract
- Concrete waste as crushed concrete aggregates (CCA) in structural concrete prolongs the technical life of the reference concrete accomplishing closed loop recycling. CCA concrete reaches the reference concrete compressive strength and workability by the densification of CCA and cement paste. Our previous study demonstrates CCA densification by mechanical pre-processing, aggregate quality improvements discerned by increased packing density giving reference concrete strength and workability. This study addresses paste densification with blast furnace slag (GGBS) to replace 30 (wt.%) of Portland cement at reference concrete w/b ratio 0.5 and a lower w/b 0.42. Two CCA replacements are investigated: fine aggregates, CCA50; overall aggregate replacement, CCA100. Compressive strength results show that both CCA50, CCA100 mixes achieve reference values at w/b 0.42, only CCA100 achieves reference value at w/b 0.5 as a climate-optimized concrete. The CCA50 mix-w/b 0.5 reaches reference strength when paste densification by GGBS is combined with CCA densification from mechanical pre-processing of aggregates. The 7-day strength of CCA100 with GGBS increases by 11% by mixing with pre-soaked GGBS. Statistical analysis of CCA100 strength results shows significant improvements with GGBS compared to mechanical pre-processing. Significant improvements are possible in CCA50 mix for a combination of mechanical pre-processed aggregates and GGBS replacement.
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| 8. |
- Sadagopan, Madumita, 1987-, et al.
(författare)
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Improving recycled aggregate quality by mechanical pre-processing
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944 .- 1996-1944. ; 13:19
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Tidskriftsartikel (refereegranskat)abstract
- Concrete with crushed concrete aggregates (CCA) shows lesser compressive strength than reference concrete with natural aggregates. The goal of this study is to improve the strength of structural concrete with 53% and 100% CCA replacements without increasing the cement content. Thus, improvements in CCA quality are induced by combining mechanical and pre-soaking pre-processing techniques. Mechanical pre-processing by rotating drum is separately pursued on fine and coarse CCA for 10 and 15 min respectively. Results show, adhered mortar content and CCA water absorption reduces as pre-processing duration increases. Pre-processing influences CCA particle grading, flakiness index, shape index, void-content, unit-weight and density, jointly seen as packing density, which increases with pre-processing duration. Water amount to pre-soak CCA before concrete mixing is stable despite grading modifications, due to reduced water absorption resulting from mechanical pre-processing. Compressive strength and workability for pre-processed CCA50 and CCA100 concrete are comparable to reference concrete and show similar trends of improvement with packing density. Packing density markedly shows the quality improvements induced by pre-processing on CCA, maybe considered as one of the quality assessment indexes for CCA. Packing density should be investigated for other recipes to see the stability of the trend with workability and compressive strength. © 2020 by the authors.
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| 9. |
- Sadagopan, Madumita, 1987-, et al.
(författare)
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Modified pycnometer method to measure the water absorption of crushed concrete aggregates
- 2020
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Ingår i: Journal of Sustainable Cement-Based Materials. - : Taylor and Francis Ltd.. - 2165-0373 .- 2165-0381. ; 9:5, s. 259-269
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Tidskriftsartikel (refereegranskat)abstract
- The water absorption of crushed concrete aggregates (CCA) has a major influence on concrete workability. In order to determine the water absorption of CCA, a more porous material than natural aggregates, modifications to the standard pycnometer method are proposed as: (1) Water absorption is measured on a combined fraction CCA consisting of fine and coarse aggregates proportioned according to concrete recipe. (2) The CCA is pre-processed to mitigate sedimentation. (3) Saturated surface dry condition of aggregate is assessed by vacuum filtration and ocular technique. Water absorption development is measured at 0 min, 15 min, and 24 h. About 90% of the 24-h water absorption occurs in 15 min, value which is introduced in the concrete recipe; slump flow and compressive strength are determined. The modified pycnometer method shortens test duration, is operator insensitive and gives reliable water absorption result for CCA leading to concrete workability fitting industrial application. © 2020, © 2020 The Author(s).
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| 10. |
- Sadagopan, Madumita, 1987-, et al.
(författare)
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Recycled Fine and Coarse Aggregates’ Contributions to the Fracture Energy and Mechanical Properties of Concrete
- 2023
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Ingår i: Materials. - 1996-1944 .- 1996-1944. ; 16:19
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the fracture mechanical properties of concrete, using crushed concrete aggregates (CCA) and granulated blast furnace slag (GGBS) for partial cement replacement. CCAs made from prefabricated concrete replace 100% of the fine and coarse fractions in concrete recipes with w/c ratios of 0.42 and 0.48. Two pre-treatment methods, mechanical pre-processing (MPCCA) and accelerated carbonation (CO2CCA), are investigated for quality improvements in CCA. The resulting aggregates show an increased density, contributing to an increase in the concrete’s compressive strength. The novelty of this paper is the superposition of the effects of the composite parts of concrete, the aggregate and the cement mortar, and their contributions to concrete fracture. Investigations are directed toward the influence of fine aggregates on mortar samples and the influence of the combination of coarse and fine aggregates on concrete samples. The physical and mechanical properties of the aggregates are correlated with mortar and concrete fracture properties. The results show that CCA concrete achieves 70% of the fracture energy values of concrete containing natural aggregates, and this value increases to 80% for GGBS mixes. At lower w/c ratios, MPCCA and CO2CCA concretes show similar fracture energies. CO2CCA fine aggregates are the most effective at strengthening the mortar phase, showing ductile concrete behavior at a w/c ratio of 0.48. MPCCA aggregates contribute to higher compressive strengths for w/c ratios of 0.42 and 0.48. Thus, mechanical pre-processing can be improved to produce CCA, which contributes to more ductile concrete behavior.
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