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- Bagheri, Hamid, 1956-
(författare)
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Prestressed hybrids of AAC and HPC : The BCE (Block Composed Element) building system. A conceptual study
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is an important potential for a development of a building system, if the present AACblock plants are completed with high performance concrete and pre-stressing technique. This can be done as a continuation of a present AAC production or in a site factory. Hybrid cooperation between AAC and concrete is not a new technology. Traditionally, AAC is covered with rendering. The wetted material is first sprayed with cement slurry after which comes lime/cement-based rendering which strengthens the wall and supplies a mechanical protection. AAC blocks can be used as infill members in concrete deck plates and concrete framed walls (Hellers, 1993), in which the shrinkage of the surrounding concrete locks completely the cured blocks into a stable composite. A good cooperation between AAC and concrete is a requirement for the pre-stressed hybrid. This combination has been investigated with reference to bond and moisture content. The interface must have sufficient bond to supply shear strength to the structural member. Also, the concrete should be suitable for pre-stressing which requires a minimum strength class K40. Here, K60 is applied in order to reduce creep and avoid creep failure of the AAC. A production layout for the purpose is suggested. This research consists of three parts: 1- Hybrid concrete elements The principal formulation of hybrids, built on cooperation between two concrete materials, a weak AAC and a strong HPC poured on top, shows that this combination unites the most favourable qualities of the two concretes into a structural element with rational building technology. Load-bearing capacity is good, and the fire protection is excellent. Through pre-stressing of the structural concrete, a crack-free behaviour is guaranteed up to the service limit, and deflection from dead weight (incl. floor covering and possibly half the service load) be eliminated. The most important structural elements needed in a building system could be taken as hybrids. In drawings, different members like floor- roof- and wall members, window and door lintels are shown. 2- Production system for hybrids AAC blocks form a bed containing the pre-stressing steel in slits and on which high performance concrete is poured. Pre-stressing brings the two concretes together. This is especially important for the shear capacity of a building member, by which extra dowels can be omitted. The pre-stressing force is anchored by plates directly against the cured AAC blocks. A special pre-stressing bed is not required. The production is arranged in such a way that necessary equipment (trays, form strips, wedges, locks) are circulated within twenty-four hours. The necessary manpower for this facility is analysed. Normally 8 men are needed per shift. A detailed conceptual production layout for a hybrid production plant is included for discussion. See figure 6.2 (suggested production layout). 3- Application in building The hybrid members are united at joints and through seams. Continuity over connections is achieved by filling seams with mortar grout. Reinforcement may be included to achieve ductility. By a similar method, it is possible to make connections between horizontal and vertical building members. Common connection details are shown in the report. This building method replaces the equivalent method with concrete or AAC members, and it is in fact a coordination between these two. The maximum span of floor members is up to 9 m. It makes the system suitable for modern residential house production, but also suitable for office buildings, industrial halls and other applications. See attached drawings, part 2 and part 3.
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| 2. |
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| 3. |
- Danielsson, Åke, et al.
(författare)
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A controlled randomized trial of budesonide versus prednisolone retention enemas in active distal ulcerative colitis
- 1987
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 22:8, s. 987-992
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Tidskriftsartikel (refereegranskat)abstract
- Sixty-four patients with active distal ulcerative colitis participated in a multicentre, randomized, investigator-blind trial to compare the effect of budesonide enema, 2 mg/100 ml, with prednisolone disodium phosphate enema, 31.25 mg/100 ml. Budesonide is a new potent corticosteroid with a rapid first-pass elimination. The patients were treated for 4 weeks, and the efficacy of the drugs were evaluated by sigmoidoscopy, histology, and subjective symptoms after 2 and 4 weeks. After 4 weeks of treatment 16 of 31 patients (52%) receiving budesonide enema had healed endoscopically, compared with 8 of 33 (24%) (p = 0.045) receiving prednisolone enema. Budesonide was superior to prednisolone in terms of both significantly improved sigmoidoscopic and histologic scores and subjective symptoms evaluated by visual analogue scales. The patients receiving prednisolone had a significant depression of endogenous cortisol levels during the treatment period, but not the patients receiving budesonide. Budesonide enema seems to be a promising therapy for active distal ulcerative colitis and causes no adverse reactions
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| 4. |
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| 5. |
- Flansbjer, Mathias, et al.
(författare)
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Tests on BCE
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Gohardani, Navid
(författare)
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Promotion of sustainable renovation in the built environment : An early stage techno-economic approach
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- According to the Swedish Government's set targets for energy use and environmental quality imposed by the European Union, the total energy per heated unit area in residential and commercial buildings will have to be decreased by 20% in 2020 and 50% by 2050 in relation to the annual consumption of 1995. The building sector should additionally be completely independent of fossil fuels for energy usage, with the increasing sector of renewable energy continuously growing until 2020. In its current state, the number of multistory buildings and single-family houses in Sweden exceeds 4 000 000 units. In order to attain the set goals, renovation of the existing housing stock is a necessity given its current relatively slow turnover. As a result of the Swedish Million Unit Program undertaken during 1965−1974, about 750 000 apartments are currently in need of renovation in order to meet today's building standards. Simultaneously, new buildings are built with energy efficiency in mind. In this study an early stage methodology is developed for building refurbishment that takes advantage of a multi-faceted approach. The methodology comprises of multiple dimensions related to a techno-economic, environmental and building occupancy approach. The work presented herein includes a thorough literature review of decision making tools within the built environment and identifies major research efforts in sustainable refurbishment. The technical aspect of this study deals with the proper identification of high-efficient insulation materials that would serve one of the set purposes of energy efficiency when utilized within building envelopes. Further, results are shown for case studies, in which economic investments in Vacuum Insulation Panels (VIPs) and a coupled heat and moisture transport for predefined configurations of VIPs with supplementary insulation of balcony slabs and wall cross-sections are considered. The developed methodology also examines simulations of the total energy consumption utilizing a set of different insulation materials such as mineral wool and VIPs, for a number of locations in Northern and Southern Europe. The research findings of this study identify several aspects of a new developed tool for decision making, to be used in sustainable renovation and refurbishment.
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| 8. |
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| 9. |
- Hellers, Bo Göran, 1939-
(författare)
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The BCE-system, prestressed hybrids of AAC and HPC
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The BCE technology opens up a new method to reinforce Autoclaved Aerated Concrete (AAC) by separating the production into two stages, primarily a block production from a traditional plant and secondarily the combining of blocks with affusion of High Performing Concrete (HPC) into prestressed hybrid panels, vertical or horizontal. The first stage means a continuous output of a limited number of standardized format blocks, up to 300 mm height, the second stage a non-standard production of individual panels following a CAD/CAM managed procedure, giving full freedom to architectural variation. The second stage can be added to existing block producing facilities, even in cases when a genuine PFA recipe is applied. The BCE horizontal panels have a higher capacity of up to 9 m span, carrying a live load of up to 6 kN/ than those with unstressed reinforcement from a traditional AAC plant. Industrial wall panels as well as roof panels may be 12 m, the latter under limited snow loads as is the case on most locations. Vertical wall panels can be designed with reduced depth but with retained capacity. In comparison with existing concrete alternatives the BCE panels are carrying a lower embodied energy, generating lower emissions in production of carbon dioxide.
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| 10. |
- Silfwerbrand, Johan, et al.
(författare)
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CBI Betonginstitutet 70 år - 1942-2012
- 2012
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Rapport (populärvet., debatt m.m.)abstract
- The Swedish Cement and Concrete Research Institute was founded in 1942. Two people contributed substantially to the realization of the plans: Professor Lennart Forsén and the industrial executive Dr. (h.c.) Ernst Wehtje. Mr. Forsén had a long experience within the cement area from both the industry and the university and Mr. Wehtje was the managing director for the cement producing company that today is called Cementa. The Institute and its building at the campus of KTH Royal Institute of Technology in Stockholm were enabled through a generous donation from twelve companies to Mr. Wehtje to celebrate his 50thanniversary. This report summarizes the Institute’s first 70 years.The report has partly a thematic and partly a chronological order. In the first Chapters, the early history is told, the Institute building is described, and the research financing is discussed. Subsequently, there are four chapters describing the 1970s, 1980s, 1990s, and the first decennium on the 21st century. Every chapter author in this part writes through his personal experience from that time. These chapters are followed by chapters describing the continuation education activities and some statistical data from the Institute publications. The report is concluded with lists of the 308 publications that are included in the Institute’s highest publication series.Since this report contrary to other Institute reports neither is a research report nor a state-ofthe-art report, there are no decisive conclusions. We may, however, note that the Institute is prospering and today (December 2012) is larger than ever. Man has used concrete in more than 2000 years but new research questions are still put which have to be answered through continuing research. The concrete research is mainly applied research and through its role between industry and university the Swedish Cement and Concrete Research has a stage to act upon
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