Application of Industrial Computerized Tomography to Analyze Air Voids Structure and Salt Scaling Resistance of Concrete

Abstract:

This paper utilizes the industrial computerized tomography to visualize and to calculate the microstructure change of concrete during cyclic freezethaw test. The results indicate that entraining air is the sufficient way for improving the frost resistance of concrete, and the suggested air content is 5%~7%. Also, the air void space directly affects the frost resistance of concrete, and concrete can well resist frost damage when the air void space is shorter than 238 μm. The airentrained concrete has significant amount of fine air voids with shortened air void space, and the fine air voids can release the ice forming pressure during freezing, thus protecting the concrete from frost damage. The ice forming pressure can barely release for nonair entrained concrete, and microcracks forms when the ice forming pressure exceeded the allowable stress of concrete, and finally results in material loss or frost damage.

Key words:frost resistance of concrete; industrial computerized tomography; microstructure; salt scaling