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Leaching of concrete : the leaching process and its effects

Ekström, Tomas LU (2003) In Report TVBM 1020
Abstract (Swedish)
Popular Abstract in Swedish

Avhandlingen presenterar en experimentell studie av urlakning av betong orsakat av vatten som tränger igenom betongen, eller av diffusion av joner till vatten på uppströmssidan. Urlakningsförloppet och dess effekter modelleras med finita-element-metoden.
Abstract
The present report presents an experimental study of leaching of concrete caused by water percolating through the concrete, or by diffusion from concrete to external water in contact. An apparatus was designed and constructed in which de-ionised water could be forced, by external pressure, through a number of concrete specimens of differing characteristics. It was found that, whereas the initial water flow was normally low and uniform, most specimens showed a rapid increase in water flow after a certain period of time. This was probably due to formation of certain distinct percolation channels. The solid material around these channels was leached, the concrete becoming disintegrated, and almost no continuous cementitious material being... (More)
The present report presents an experimental study of leaching of concrete caused by water percolating through the concrete, or by diffusion from concrete to external water in contact. An apparatus was designed and constructed in which de-ionised water could be forced, by external pressure, through a number of concrete specimens of differing characteristics. It was found that, whereas the initial water flow was normally low and uniform, most specimens showed a rapid increase in water flow after a certain period of time. This was probably due to formation of certain distinct percolation channels. The solid material around these channels was leached, the concrete becoming disintegrated, and almost no continuous cementitious material being left to maintain strength and tightness of the concrete. The chemical composition of the percolated water was analysed, making it possible to calculate the amount of leaching and consequently to theoretically assess the increase in porosity and reduction of strength Changes in the structure of concrete caused by leaching were also investigated experimentally by measurements of porosity, pore size distribution and strength. ESEM-EDX-studies were made in order to find out the morphology of leached concrete. Results from all these experimental studies are presented in the report. A theoretical model of the leaching process and its effects on the material and on the structural stability of real structures was developed. The model is applied to the experimental data. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Hooton, Doug, University of Toronto, Canada
organization
publishing date
type
Thesis
publication status
published
subject
keywords
material technology, water permeability., concrete dams, byggnadsteknik, building construction, leaching, materiallära, materialteknik
in
Report TVBM 1020
pages
296 pages
publisher
Division of Building Materials, LTH, Lund University
defense location
Hörsalen, Kårhuset, John Erikssons väg 3, Lund Institute of Technology
defense date
2003-06-05 10:15
external identifiers
  • other:ISRN: LUTVDG/TVBM--03/1020--SE(1-296)
ISSN
0348-7911
ISBN
91-628-5720-7
language
English
LU publication?
yes
id
d5fc03fb-69ea-4344-8dbb-00d4b3ee11ef (old id 21249)
date added to LUP
2007-05-28 14:40:21
date last changed
2018-05-29 11:13:29
@phdthesis{d5fc03fb-69ea-4344-8dbb-00d4b3ee11ef,
  abstract     = {The present report presents an experimental study of leaching of concrete caused by water percolating through the concrete, or by diffusion from concrete to external water in contact. An apparatus was designed and constructed in which de-ionised water could be forced, by external pressure, through a number of concrete specimens of differing characteristics. It was found that, whereas the initial water flow was normally low and uniform, most specimens showed a rapid increase in water flow after a certain period of time. This was probably due to formation of certain distinct percolation channels. The solid material around these channels was leached, the concrete becoming disintegrated, and almost no continuous cementitious material being left to maintain strength and tightness of the concrete. The chemical composition of the percolated water was analysed, making it possible to calculate the amount of leaching and consequently to theoretically assess the increase in porosity and reduction of strength Changes in the structure of concrete caused by leaching were also investigated experimentally by measurements of porosity, pore size distribution and strength. ESEM-EDX-studies were made in order to find out the morphology of leached concrete. Results from all these experimental studies are presented in the report. A theoretical model of the leaching process and its effects on the material and on the structural stability of real structures was developed. The model is applied to the experimental data.},
  author       = {Ekström, Tomas},
  isbn         = {91-628-5720-7},
  issn         = {0348-7911},
  keyword      = {material technology,water permeability.,concrete dams,byggnadsteknik,building construction,leaching,materiallära,materialteknik},
  language     = {eng},
  pages        = {296},
  publisher    = {Division of Building Materials, LTH, Lund University},
  school       = {Lund University},
  series       = {Report TVBM 1020},
  title        = {Leaching of concrete : the leaching process and its effects},
  year         = {2003},
}