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Academic literature on the topic 'Självkompakterande betong'
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Dissertations / Theses on the topic "Självkompakterande betong"
Tanndal, Josefin, and Roth Matilda Cantera. "Undervattensgjutning med självkompakterande betong." Thesis, KTH, Byggteknik och design, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231278.
Full textCasting with concrete under water is challenging, and requires high standards on both the concrete and the work practice to achieve good results. Peab noticed problems with this type of casting, and wanted to clarify the difficulties to increase the chance of good results with future underwater castings. The problems were injuries on the finished concrete structure and troubles with the concrete during casting such as foam and separation in the concrete. This paper compiles the difficulties with underwater casting with self-consolidating concrete (SCC) and investigates the factors that affect the final result. This has been done through interviews with experienced people, a literature review and visits to construction site that performed underwater casting. This paper identifies four main issues; pre-casting planning, concrete quality, form and work procedure. The planning is very important but difficult, as many factors need to be considered, such as weather, land traffic and boat traffic. In order to minimize the risk of unwanted breaks during casting, it is good to have a preparatory plan with solutions to problems that may occur. The difficulty with concrete is that it's a living, and thus unpredictable, material. It is very important that the concrete has good cohesion so that the concrete's cement paste is not washed out in the water. It is also necessary that the concrete has good consistency to ensure it will enclose all reinforcement and fill in the entire form. The concrete is tested when it arrives to the construction site. Among other things, the air content as well as homogeneity and flowability are controlled, the latter controlled by a slump flow test. It is important to take these controls into consideration, and to make the decision not to cast with bad concrete. The requirements on the form used during underwater casting are high. It must be completely dense and properly constructed so that foam and sludge can flow out of the form. One difficulty is that the divers sometimes need to build parts of the form under the water. The work practice is challenging as it's complicated and done blindly. The used method is to pump concrete under the water surface through a concrete pipe with an underwater valve. During the casting process, the mouth of the pipe must always be below the concrete surface and the casting tube should be kept vertically. Finally, it is worth mentioning that the literature available today about underwater casting is inadequate, which makes it difficult to learn about the subject. The suggested solutions presented in the report are that all concrete coming to the construction site should be tested, even though it is not always a requirement. Thus, the decision of whether the concrete had a high enough quality for casting would be made for each delivery. In order to increase the chances of the concrete having desired properties, it is important that the truck delivering concrete to the construction site is clean and does not contain residues of a different concrete. Throughout the work, a good communication between pump operator, diver and management is needed to jointly solve problems. At last, it is recommended to help each other and take advantage of the expertise and experience within the company.
Elofsson, Andreas, and Mikael Hallin. "Självkompakterande betong : Ytjämnhet utan efterbehandling." Thesis, Karlstad University, Division for Engineering Sciences, Physics and Mathematics, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-175.
Full textBetonggjutning är ett tungt moment inom byggproduktion och entreprenörer har länge använt betong med flyttillsats för att få en mer lättarbetad betong. Ändå har det krävts långa arbetspass och många tungarbetade moment. Efter lasernivellering, vibrering, slodning och glättning har man kunnat uppnå en yta som nästan är helt jämn. Dock ej så jämn att avjämningsmassa kunnat elimineras för att inte få sviktande parkett eller buktande plastmattor.
Självkompakterande betong (SKB), eller vibreringsfri betong som man först kallade den, forskades fram på 80-talet i Japan och dök upp i Sverige i slutet på 90-talet. Det är en betong som innehåller en flyttillsats och en så kallad filler vars gemensamma egenskaper ger en betong som har bibehållen homogenitet samtidigt som den fyller ut formen och omsluter armering endast genom gravitationskraften. SKB är ca 10-15 % dyrare än traditionell betong men har motiverats med framförallt minskad produktionstid, färre betongarbetare och bättre arbetsmiljö.
Eftersom SKB mer eller mindre är flytande så blir jämnheten mycket god. Erfarenhetsmässigt har ytorna blivit i det närmaste perfekta efter lasernivellering, slodning och torrslipning. Trots stora konstaterade arbetsmiljövinster och vetskapen om den goda ytjämnheten har AB Färdig Betong i Karlstad endast levererat SKB till 8 projekt sedan 1997.
Examensarbetets syfte är att fastställa om SKB kan motiveras baserat på den goda ytjämnhet som kan uppnås redan efter gjutning jämfört med normalpresterande betong (NPB).
Examensarbetet har utförts i samarbete med Skanska Sverige AB i Karlstad, som under våren 2006 genomförde två projekt med SKB. Mätningar av ytor med SKB gjordes på Färjstad i Karlstad och mätningar av referensytor med NPB gjordes i Karlstad med omnejd. Mätningarna kompletteras med intervjuer i form av erfarenhetsåterföring från dem som tillverkat, levererat, mottagit, gjutit och efterbehandlat betongtypen.
De krav på ytjämnhet av platsgjuten betong som generellt tillämpas återfinns i Hus AMA 98 och definieras som buktighet, lutning och nivåskillnad. Resultaten från mätningarna bedömdes i enlighet med Hus AMA 98, därefter har betongtypernas mätvärden analyserats och jämförts.
Utifrån resultaten har bland annat följande slutsatser kunnat konstateras:
Självkompakterande betong kan vid rätt handhavande ge en yta som uppfyller kraven enligt Hus AMA’s krav för undergolv i klass B utan varken vibrering, slipning eller efterbehandling.
Användandet av SKB i större bostadsprojekt skapar stora förutsättningar för lägre totalekonomi jämfört med användandet av NPB. Detta baseras huvudsakligen på minskat behov av arbetskraft vid gjutning och efterbehandling av den gjutna ytan.
De bekräftade möjligheterna för förbättrad ytkvalitet redan efter gjutning kommer i framtiden innebära att fler entreprenörer väljer SKB.
Concrete moulding is a heavy moment in the building process and for a long time contractors have used an admixture to create a concrete that is easier to handle. However many hours of work and heavy moments has been required. After laser levelling, vibrating, screeding and troweling a surface that is almost flat has been obtained. Yet not flat enough to eliminate floor levelling and thereby avoiding bending parquet flooring or curved plastic flooring.
Self-compacting concrete (SCC), or vibrating free concrete as it was named in the beginning, was developed in the eighties in Japan and showed up in Sweden in the late nineties. It is a concrete that contains an admixture and filler that together makes the concrete flow under its own weight, completely filling the formwork and achieving full compaction, even in the presence of congested reinforcement. SCC is approximately 10-15 % more expensive than traditional concrete but is motivated with faster construction times, fewer workers and an improved work environment.
Since SCC just about flows the resulting surface becomes almost perfect. Experience shows that surfaces are nearly perfect after laser levelling, screeding and dry smoothing. Despite the advantages of the flat surfaces and the established improvement on the work environment, AB Färdig Betong in Karlstad, Sweden has only delivered SCC to eight projects since 1997.
The aim of this degree thesis is to determine if SCC can be motivated based on the flat surfaces that can be obtained after moulding compared to traditional concrete.
The degree thesis has been performed in cooperation with Skanska Sverige AB in Karlstad, Sweden at their two projects with SCC in spring 2006. The measurement of SCC surfaces was made in Färjestad, Karlstad and reference measurements of traditional concrete was made in Karlstad and surroundings. The measurement have been complemented with interviews that present experience of producing, delivering, receiving, moulding and after treating SCC.
The requirements for on site moulding concrete surfaces that are to be followed are found in Hus AMA 98 and is defined as curve, rake and level variance. The result from the measurements are judged on the basis of the requirements.
Conclusions
Correctly performed SCC can create a surface that fulfils the requirements in Hus AMA 98 for a class B floor.
The use of SCC in larger housing constructions makes conditions for a lower total cost. This is based principally on fewer workers, faster construction times and less after treatment of the moulded surfaces.
The confirmed possibilities of improved surfaces after moulding should mean that more contractors will use SCC in the future.
Lennartsson, Jessica, and Ida Hildingsdotter. "Självkompakterande betong vid platsgjutning av anläggningskonstruktioner." Thesis, Halmstad University, School of Business and Engineering (SET), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-2617.
Full textBy using modern methods of casting concrete, cast in place can get more effective and industrialized. A modern method is self compacting concrete. By using this type of concrete, advantages like improved working environment and rationalized construction can be reached. Because the concrete doesn’t need to be vibrated, the amount of staff on site and the noise can be reduced.
Self compacting concrete has been used in Sweden for over 10 years, still it only stands for
5 % of the cast in placed concrete in the country. This report deals with, why self compacting concrete isn’t used more often when casting in place within civil engineering.
The result is that self compacting concrete with “anläggningscement” (Swedish low heat Portland cement) is a sensitive product because many factors needs to be correct to reach a good result. A reason fore this sensitivity is that the recipe of the concrete has a low tolerance for variations in the different components. Small variations can lead to changes in the consistency which means that the concrete is destroyed and this will result in delay of the delivery to the site. When casting self compacting concrete it’s dependent that the flow of fresh concrete comes continuously, otherwise the concrete can start to cure.
The problem that self compacting concrete is a sensitive product needs to be resolved to ensure that this concrete can help casting in place to be industrialized within civil engineering.
Norén, Sara, and Sandra Axelsson. "Betong - Förvånansvärt lättflytande!" Thesis, Halmstad University, School of Business and Engineering (SET), 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-938.
Full textConcrete is a very common construction material. It´s characteristics are strength, durability and formablility. Superplasticizer is a common admixture, which changes the properties of concrete.
Today (spring 2007) there are no certian mathematical methods to calculate the required percentage of this admixture needed to give the necessary set slump flow in the overall concrete recipe.
Concrete batching companies must therefor experiment with different amount of superplasticizer in order to meet the specified slump and strength.
The purpose og this report is to investigate if any mathematical relation can be established between the amount of superplasticizer used and the slump flow achieved.
After carrying out some practical experiments using four different superplasticizers a direct relationship can be establish between the percentage of admixture used and the slump/flowability achieved. Unfortunatly at present due to the numerous variables, the calculation of mathematical formula can not be achieved.
Hussein, Alwan Kamal, and Husam Haseeb Khamees. "Självkompakterande betong (SKB : förbättrad arbetsmiljö och konstruktion." Thesis, KTH, Byggteknik och design, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-147537.
Full textSelf-compacting concrete (SCC) or vibrated concrete was invented and developed in Japan in the late 1980's. Working with concrete is very hard and all of that is because of injuries that come from using of the usual concrete. In Sweden, they used self-compacting concrete since 1993 when the technology has brought to Sweden from Japan by the Swedish cement and concrete Research institute. Self-compacting concrete has many advantages that are different from the traditional concrete according to the work environment which include avoidance of vibration and heavy work and all these can reduce the number of injuries at workplace. Shortened construction time and possibilities to save manpower are additional benefits. Today, self-compacting concrete is used for about 10 % on site casting in Sweden. Many other countries have gone forward in using of SCC, Denmark uses about 30%. The low use is due to the sensitivity of SCC and expensive because it contains more filler. The main work of the project consists of the interviews with the related persons in the building branch and questions to them about self-compacting concrete to get the maximum amount of information. Information that we have received was between eight visits and six mail. The aim of the thesis is to increase knowledge about the cause of the low development of SCC in place casting and knowledge of the work environment. Furthermore, this work aims to highlight the work environment and constructive advantages and disseminate information about them. The study shows that the reason for the low use of SCC is especially the price. But the previous failures and varying concrete properties are also such of these reasons. Increasing the use of SCC leads to many benefits including economic profit in the long term, and especially from the society side.
Ström, Martin. "Väggjutning med självkompakterande betong : Vad påverkar gjutresultatet?" Thesis, Karlstads universitet, Fakulteten för teknik- och naturvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-7874.
Full textPak, Alexander, and Reazhwan Saleh. "Krossad betong som ballast i självkompakterande betong : Experimentell studie om tryckhållfasthet och arbetbarhet." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-15345.
Full textThis project is based on experimental studies. It is about the preparation and evaluation of self-compacting concrete (SCC) using Recycled Concrete Aggregate (RCA), replacing all natural aggregate fractions with 100% RCA. This degree project is part of RE:Concrete and focuses on concrete workability and compressive strength. The work was carried out in collaboration between the University of Borås and RISE CBI Concrete Institute. The purpose of the thesis was to produce a SCC with 100% RCA. Furthermore, cast cubes would give a compressive strength equivalent to 40 MPa after 7 days and 60 MPa after 28 days. Recycling of building materials is a hot topic in today's society, and interest in it is constantly increasing. This work is about closed loop recycling in the sense that RCA has been obtained from supporting elements to make SCC for supporting elements. As of today, there is a standard in Sweden regulating the use of recycled building materials in concrete production. The standard only deals with replacement of coarse aggregates in limited proportions. The results obtained in this work show that it is fully possible to manufacture a concrete for supporting structures. The highest compressive strength value obtained in this study is 56.1 MPa after 7 days with a slump flow meeting SCC requirements, however, this concrete had poor workability due to high dose of superplasticizer. In the last experimental casting, a slump flow of 750 mm has been achieved with good workability and a compressive strength after 7 days at 26.1 MPa. The latter provides a SCC with a strength class C20 / 25.
Emanuelsson, Erik. "Beräkningsmodeller för att beräkna formtryck vid gjutning med självkompakterande betong." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68332.
Full textValden, Roger, and Temesgen Nehemiah. "Acceleratorers inverkan på betong avseende bearbetbarhet, pumpbarhet och hållfasthetstillväxt." Thesis, Uppsala universitet, Institutionen för samhällsbyggnad och industriell teknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415478.
Full textGram, Annika. "Numerical Modelling of Self-Compacting Concrete Flow : Discrete and Continuous Approach." Licentiate thesis, KTH, Civil and Architectural Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10288.
Full textWith the advent of Self-Compacting Concrete (SCC) that flows freely, under the soleinfluence of gravity, the wish for hassle-free and predictable castings even in complexcases, spurged the simulation of concrete flow as a means to model and predictconcrete workability. To achieve complete and reliable form filling with smoothsurfaces of the concrete, the reinforced formwork geometry must be compatible withthe rheology of the fresh SCC. Predicting flow behavior in the formwork and linkingthe required rheological parameters to flow tests performed on the site will ensurean optimization of the casting process.In this thesis, numerical simulation of concrete flow is investigated, using both discreteas well as continuous approaches.The discrete particle model here serves as a means to simulate details and phenomenaconcerning aggregates modeled as individual objects. The here presented cases aresimulated with spherical particles. However, it is possible to make use of nonsphericalparticles as well. Aggregate surface roughness, size and aspect ratio maybe modeles by particle friction, size and clumping several spheres into forming thedesired particle shape.The continuous approach has been used to simulate large volumes of concrete. Theconcrete is modeled as a homogeneous material, particular effects of aggregates,such as blocking or segregation are not accounted for. Good correspondence wasachieved with a Bingham material model used to simulate concrete laboratory tests(e.g. slump flow, L-box) and form filling. Flow of concrete in a particularly congestedsection of a double-tee slab as well as two lifts of a multi-layered full scale wall castingwere simulated sucessfully.A large scale quantitative analysis is performed rather smoothly with the continuousapproach. Smaller scale details and phenomena are better captured qualitativelywith the discrete particle approach. As computer speed and capacity constantlyevolves, simulation detail and sample volume will be allowed to increase.A future merging of the homogeneous fluid model with the particle approach to formparticles in the fluid will feature the flow of concrete as the physical suspension thatit represents. One single ellipsoidal particle falling in a Newtonian fluid was studiedas a first step.
Med uppkomsten av självkompakterande betong (SKB) och dess möjligheter att flyta ut under inverkan av endast gravitation uppstod ett behov av att kunna förutsäga och kontrollera även mer komplicerade gjutningar. Numerisk simulering av SKBs flöde kan kommma att utgöra ett kraftfullt verktyg för att optimera gjutprocessen, ge möjlighet att förutsäga nödbvändig arbetbarhet och säkerställa kompatibilitet mellan den armerade formen och betongens reologi. I föreliggande avhandling undersöks betongens flöde med både diskreta och kontinuumbaserade simuleringsmetoder. Den diskreta partikelmodellen används för att simulera detaljer och fenomen hos t.ex. ballast i betong. I de här presenterade simuleringarna används sfäriska partiklar, men det är även möjligt att skapa ballastkorn av olika form. Ballastens ytråhet och storlek kan modelleras med parametrar för friktion och storlek medan sammanfogning av ett flertal partiklar kan ge ekvivalent form. Den kontinuumbaserade ansatsen används för att simulera större flödesmängder. Betongen modelleras som ett homogent material, eventuella effekter av ballastens inverkan, till exempel blockering eller separation, ingår ej. God överensstämmelse har uppnåtts med Binghams materialmodell som applicerats på några av SKBs provningsmetoder (bl a flytsättmått och L-låda) liksom även för större gjutningar. Formfyllnad av en hårt armerad sektion av ett STT-element, liksom två pumpade betongleveranser till en hög vägg, har framgångsrikt simulerats. En kvantitativ övergripande analys av betongflödet i formen kan göras med den kontinuumbaserade ansatsen för att upptäcka zoner med eventuella svårigheter. En högupplöst detaljstudie kompletterar sedan analysen på valda delar av och kring dessa zoner för att fånga partikelfenomen kvalitativt med hjälv av den diskreta modellen. Då datorkapaciteten ökar kommer även större volymer med högre detaljrikedom att kunna simuleras. En framtida modell simulerar med stor sannolikhet partiklar i flöde, vilket till fullo kan fånga betongens egenskaper som suspension. Som ett första steg på vägen har en fallande ellipsoid i en newtonsk vätska simulerats.