A Three-Phase Transport Model for High-Temperature Concrete Simulations Validated with X-ray CT Data.

Area of Science:

• Civil Engineering
• Materials Science
• Thermodynamics

Background:

• High temperatures cause thermo-hygral phenomena in concrete, leading to pore pressure buildup and spalling.
• Existing models struggle with solid mass balance due to independent treatment of porosity and dehydration.

Purpose of the Study:

• To propose and validate a novel three-phase transport model for predicting concrete behavior under high temperatures.
• To improve the accuracy of thermo-hygral phenomena prediction by ensuring solid mass balance.

Main Methods:

• A three-phase transport model was developed, incorporating a new formulation for porosity and dehydration.
• The model was validated using X-ray computed tomography (CT) data up to 320 °C.
• Neutron radiography data informed the dehydration formulation, replacing traditional thermogravimetric analysis.

Main Results:

• The model demonstrated good agreement with experimental data for temperature profiles and moisture changes.
• The new formulation successfully ensured solid mass balance, a limitation in previous approaches.
• Accurate prediction of thermo-hygral phenomena, crucial for spalling assessment, was achieved.

Conclusions:

• The proposed three-phase transport model accurately predicts concrete's response to high temperatures.
• Ensuring solid mass balance through independent porosity variable is critical for reliable modeling.
• The validated model offers improved insights into concrete spalling mechanisms.