Microstructure and permeability changes of paste under the calcite deposition and leaching process

Title: Microstructure and permeability changes of paste under the calcite deposition and leaching process
Author(s): Y. You, G. Ye, C. Qian, C. Miao, K. van Breugel
Paper category : conference
Book title: International Conference on Microstructure Related Durability of Cementitious Composites
Editor(s): W. Sun, K. van Breugel, C. Miao, G. Ye and H. Chen
Print-ISBN: 978-2-35158-065-3
e-ISBN: 978-2-35158-084-4
Publisher: RILEM Publications
Publication year: 2008
Pages: 647 - 656
Total Pages: 10
Nb references: 26
Language: English

Abstract: Microsture performance of pastes under calcite deposition and leaching proecess are presented in this article. From experiments it was found that the penetrable calcite deposited with the complex function of carboxylic acid supplied by self healing promoted materials (SHPM) could reduce the permeability and porosity of cement paste. The SHPM is used to coat on the surface of cementitious materials to reduce the permeability by penetrable deposition of proliferated calicte from surface to internal matrix. Permeation characteristics are parallel studied on the samples blended with feasible magnesium salt and curing in dilute carboxylic acids solution without SHPM coating. The sample coated with SHPM consisting of carboxylic acid with one hydroxyl group per molecule showed lowest permeability and porosity, while the permeability of paste blended with magnesium salt and cured in dilute carboxylic acidic solution dramatically increase during the leaching period. The calcite morphologies chelated by three carboxylic acids are compared with Scanning Electron Microscopy (SEM) observation. With the increase of the number of hydroxyl group in a carboxylic acid molecular, the deposit calcite particle turn to be more spherical, which indicated a higher dissolution and more favorable to deposit in lower concentration of carboxylic acid. The redistribution of the pore size of the samples after permeation test revealed the process of calcite dissolution, precipitation and clog in porous cementitious materials. This study is aimed to explore the mechanism of self healing process of carbonated concrete in ambient weak acidic saturated environment.

Online publication: 2009-06-09
Publication type : full_text
Public price (Euros): 0.00