VAKUUMBEHANDLING AV BETONG
The literature was surveyed and tests were carried out in an effort to find what improvements in quality occur in the concrete at varying depths below the surface. A method was also devised to confirm these improvements, primarily the increase in strength. The literature review indicated that it is the redistributions of pressure in the concrete during the vacuum treatment which squeeze water out of the concrete and thereby increase its strength. Details are given of the determination of the changes in concrete properties due to vacuum treatment. During vacuum treatment the quantity of water removed from the concrete was measured by collecting the water extracted and also by recording the loss in weight of the slab. Vacuum in the concrete was measured using water-filled sleeves cast into the concrete and connected to a pressure gauge. The strengths of the slabs were determined on cores taken from the slabs. It was possible to detect a relationship between strength and suction period, quantity of water extracted, compression and vacuum in the concrete. The effect of vacuum treatment on shrinkage was determined by drilling cores horizontally from the sides of the slabs at different levels. Details are outlined of a method of estimating the final strength on the basis of behavior during vacuum treatment, and it is shown how a graphical relationship may be used to determine the water-cement ratio which is equivalent to a stipulated strength, and to calculate in advance how much water may be extracted from a certain level in the concrete. It is also shown how it is possible to determine continuously how much water has been extracted from a certain level and thus the strength which is to be expected.
- This article is taken from summaries and synopsis of the National Swedish Council for Building Research.
National Swedish Council for Building ResearchLinnegatan 81
114 60 Stockholm, Sweden
- DAHL, G
- JOHANSSON, A
- Publication Date: 1974
- Features: Figures;
- Pagination: 2 p.
- TRT Terms: Compression; Pressure; Reviews; Soil suction; Strength of materials; Testing; Ultimate strength; Underground structures; Water; Water cement ratio
- Uncontrolled Terms: Suction
- Old TRIS Terms: Vacuum concrete method
- Subject Areas: Bridges and other structures; Highways; Materials;
- Accession Number: 00082879
- Record Type: Publication
- Report/Paper Numbers: S51:1974
- Contract Numbers: C-1032
- Files: TRIS
- Created Date: Mar 26 1975 12:00AM