Microstructural modeling of heated portland cement paste

Author(s): Qi Zhang, Guang Ye
Paper category: Conference
Book title: 2nd International conference on Microstructural-related Durability of Cementitious Composites
Editor(s): Guang Ye, K. Van Breugel, Wei Sun, Changwen Miao
Print ISBN: 978-2-35158-129-2
e-ISBN: 978-2-35158-123-0
Publisher: RILEM Publications SARL
Pages: 848 - 856
Total Pages: 8
Language: English

Abstract: 
When Portland cement paste is exposed to high temperature, a complex chemical transformation takes place. Calcium hydrate silicate (C-S-H) starts to dehydrate at about 105 ℃, and Calcium hydroxide dehydrates at about 430 ℃. Along with the chemical reactions, the hydration products (C-S-H and CH) shrink, while the volume of unhydrated clinker almost keeps the same. Due to the strain mismatch in microstructure, micro cracking might occur. These chemical reactions lead to the irreversible change of microstructure of Portland cement paste, which can affect the mechanical properties and transport properties.

In this study, a microstructural model is proposed to simulate the microstructural change of Portland cement paste at high temperature. The physiochemical transformation in cement paste is characterized first. The dehydration kinetics of cement paste, the volume change of hydration products and the microstructure change are formulated. Then the lattice model is performed to simulate the micro cracking and microstructure change. Finally, in order to verify the simulation model, the simulated microstructure of heated Portland cement paste is compared with the microstructure obtained by experiments.

Online publication: 2013
Publication Type: full_text
Public price (Euros): 0.00