Leaching of concrete : the leaching process : extrapolation of deterioration : effect on the structural stability

Other literature type, Report English OPEN
Fagerlund, Göran (2000)
  • Publisher: Division of Building Materials, LTH, Lund University
  • Journal: (issn: 0348-7911)
  • Subject: Materials Engineering | Materialteknik

The leaching process when water attacks concrete, and the effect of leaching on the strength and durability of a concrete structure, is analysed theoretically. Technique for prediction of the future leaching<br /> and structural stability is outlined. The analysis is to a certain extent supported by data from literature. The leaching process is divided in five different types: 1: Pure surface leaching 2: Surface leaching involving erosion<br /> 3: Homogeneous leaching over the entire structure<br /> 4: Semi-homogeneous leaching over the entire structure<br /> 5: Leaching in defects within the structure<br /> For each type, the physical leaching process is outlined. Consideration is taken to the increase in<br /> permeability caused by leaching making it theoretically possible to predict the future leaching from an<br /> analysis of the water flow and degree of leaching at the time of inspection of the structure.<br /> The effect of leaching on strength and E-modulus of the concrete is analysed showing that the effect can<br /> be substantial.<br /> A short discussion is made on the effect of leaching on the structural stability and on the changes in<br /> structural stability in the future. Important mechanical factors discussed are changes in compressive<br /> strength, tensile strength and bond strength between reinforcement and concrete. The increased risk of<br /> reinforcement corrosion and frost damage in leached concrete is discussed and found to be big. The<br /> effect of changes in the internal uplift pressure in dams due to changed flow paths inside the dam and the<br /> effect of these changes on the dam stability are mentioned.<br /> Finally, in an APPENDIX, a simple method is outlined for how to assess the concrete strength from<br /> information of the physical composition of the cement paste. By this theory it is also possible to assess<br /> the effect of leaching on the concrete strength.
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