Industrial bridge construction with cast in place concrete: new production methods and lean construction philosophies

The construction industry is associated with high costs, low productivity, a lack of quality and low profit margins. Too often the actual cost for a project exceeds the expected cost. Industrialization of the construction industry is said to be the key to success and its definition is often debated, but what is the meaning of industrialization? The project has so far comprised different forms of full scale studies, laboratory studies and theoretical work. Ten bridge projects were examined. The results from this study were studied with regards to new production methods. Unit times for SCC (self compacting concrete) were thus compared with unit times for traditionally vibrated concrete, unit times for rebar carpets were compared with unit times for traditionally clenched reinforcement, and also the effects of left formwork were studied. To try to verify the theoretical results, mainly two full scale studies have been carried out. The first was a replacement of an existing bridge on the European road No 4 outside Kalix in the northern parts of Sweden. Here prefabricated reinforcement cages to the foundation and SCC to the whole project were used. Also rebar carpets were used for the superstructure. The reinforcement in a typical bridge superstructure of today most often consists of approximately 80 per cent longitudinal reinforcement and 20 per cent shear force reinforcement. The project aimed at examining if it was technically feasible to use rebar carpets and if there were any economical benefits in using it. The aim was also to examine if it was economical to prefabricate reinforcement cages and transport them to the site for placement in comparison to traditionally fix reinforcement piece by piece. The other full scale project was concentrated on the use of SCC, but also the rebar carpets were examined to some extent. Here, the design phase was not followed by the researchers and no redesign for maximizing the use of carpets was performed. The aim for the project was above all to examine the economic conditions associated with the use of SCC, and to study the working environment in connection to the casting of SCC compared to traditionally vibrated concrete. The largest economic benefit from introducing SCC to a contractor in civil engineering projects is probably on the superstructure of a bridge, since the largest number of workers is needed during casting of traditional vibrated concrete and it is therefore associated with large casting costs. Hence, the number of workers needed for casting can be markedly reduced if SCC is introduced and proper planning has been carried out. However, controversially it is often easier to introduce SCC for foundations, columns or plate structures since these structural parts are less dominant in the construction and the risk related to using SCC is small. However, for these smaller, less people demanding castings it is more difficult to achieve economical benefits in using SCC. The overall risk using SCC is that the product it is not robust enough, which might result in the concrete does not enclose the reinforcement satisfactory and rework is needed. Probably the largest benefit with using SCC is, as mentioned earlier, the improvement in working environment. Therefore, the economy of the Swedish construction industry and society can benefit significantly from using the right kind of working method during construction (A). http://pure.ltu.se/ws/fbspretrieve/1810763.

Language

  • English

Media Info

  • Pagination: 56p+app
  • Serial:
    • Licentiate thesis
    • Issue Number: 2008:17
    • Publisher: Luleå University of Technology, Sweden
    • ISSN: 1402-1757

Subject/Index Terms

Filing Info

  • Accession Number: 01122859
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • ISBN: 978-91-85685-12-7
  • Files: ITRD
  • Created Date: Mar 2 2009 7:56AM