Experimental Investigation of Changes in Pore Structure of Leached Cement Pastes
Author(s): Lin Liu, Xuecheng Wang, Huisu Chen and Jian Zhou
Paper category: Proceedings
Book title: 3rd International RILEM Conference on Microstructure Related Durability of Cementitious Composites
Editor(s): Changwen Miao, Wei Sun, Jiaping Liu, Huisu Chen, Guang Ye and Klaas van Breugel
Publisher: RILEM Publications SARL
Publication year: 2016
Total Pages : 8
Language : English
Abstract: Calcium leaching is an important issue related to the durability and long-term service life of concrete structures. For the purpose of comprehensively understanding the damage process of cement-based materials due to calcium leaching, this study aims to investigate the characteristics of pore structure of leached cement paste at different stages (low-grade, middle-grade and high-grade decalcification). In this study, an accelerated calcium leaching test on disc-like cement paste samples of about 1 mm thick was performed using 6 mol/L ammonium nitrate solution. By using the disc-like samples, the leaching gradient can be avoided. Both the change of sample mass over time and the amount of calcium ion leached out were monitored during the test. Corresponding to each mass loss, from the amount of leached calcium ion tested by Ethylene Diamine Tetraacetic Acid complex titration (EDTA), the ratio of calcium to silicate (Ca/Si) can be obtained by an inverse calculation. Two experimental techniques, mercury intrusion porosimetry (MIP) and low temperature calorimetry (LTC), were utilized to obtain the pore structure of leached cement pastes.
Changes in the pore structure of cement pastes with the changing mass loss and the changing Ca/Si were presented, and comparison of the pore structure by MIP and by LTC are discussed.
Online publication : 2016
Publication type : full_text
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