Evolution of pore structure and interfacial transition zone of concrete in seawater environment

Author(s): Ping Duan, Zhonghe Shui and Guiming Wang
Paper category: conference
Book title: Microstructural-related Durability of Cementitious Composites
Editor(s): Guang Ye, K. van Breugel, Wei Sun and Changwen Miao
Print ISBN: 978-2-35158-129-2
e-ISBN: 978-2-35158-123-0
Publisher: RILEM Publications SARL
Publication year: 2009
Pages: 150 - 160
Total Pages: 11
Language: English

Abstract: When served in seawater environment, concrete experiences a number of physical and chemical deterioration processes. The pore structure and interfacial transition zone (ITZ) in seawater concrete as indicators of marine concrete durability were explored and analyzed in this study. Some techniques such as MIP and SEM were employed to characterize the evolution of the pore structure and ITZ with the curing time.
The experimental results show that compared to normal concrete, concrete subjected to the simulated seawater condition at early ages has a higher ratio of fine porosity as well as a higher ITZ microhardness and a narrower width of ITZ. Up to 28 days, these situations are reversed. Meanwhile, there exists some microcracks in the marine concrete. After 180 days, the microstructure of concrete in seawater becomes worse. With the addition of slag, silica fume and metakaolin, the pore characteristics of marine concrete are greatly improved. Pore structure in the marine concrete is optimized, and pore size distribution is more reasonable. Microhardness of ITZ increases and the width of ITZ decreases. The effect of the mineral
admixtures on microstructure is in the sequence: metakaolin > silica fume >slag. Results of the compressive strength keep agreement with the above findings.
The mechanisms of the evolution of the microstructure were analyzed by means of the test results with advanced testing techniques.
Key words: concrete pore structure; microstructure; ITZ; seawater corrosion; mineral admixture

Online publication: 2012-05-16
Publication Type: full_text
Public price (Euros): 0.00