High-performance and self-compacting concrete in house building. Field tests and theoretical studies of possibilities and difficulties

University dissertation from Division of Building Materials, LTH, Lund University

Abstract: Cast in-situ concrete is the most frequently used materials technology worldwide within production of structural frames in multi-storey residential buildings. In Sweden, this technology dominates the market but is challenged by other competitive production methods. The criticism concerns issues as for instance short slab spans (limited flexibility for future refurbishment), long production times, unhealthy work environment and indoor air problems. Many of these disadvantages are due to the fact that by tradition ordinary low-grade concrete is used in house building. Extensive concrete materials research on high-performance concrete (HPC) and self-compacting concrete (SCC) has revealed opportunities to counter the criticism, but the technologies are not yet utilised in house building to large extent. The research project aims at investigating the potential of HPC and SCC for competitive production, structural design and function of structural frames of cast in-situ concrete in house building. The first part of the research project is dominated by production studies performed in field with the aim of investigating the ‘real’ potential of SCC addressing technical/practical and economical issues. These case studies consist of observations and measurements of the consequences when normal concrete is replaced by SCC. The result shows that SCC has a large potential for both increasing the production efficiency and improving the work environment. In the second part of the project, the theoretical potential of HPC is investigated by several parameter studies where HPC is compared with ordinary concrete as well as an interview study focusing on building process issues. The main conclusions from these studies are that use of HPC can reduce the production time strongly (by rapid drying and strength development), increase the slab span significantly (through utilisation of increased tensile strength and E-modulus) and also increase the building function (increased flexibility, acoustic and indoor air quality). When it comes to technical and building process related obstacles for the implementation of HPC and SCC, these are analysed and described together with proposed solutions.