Pore system measurement

Zheng Liu, Purdue University

Abstract

Properties of porous materials are mostly dominated by their pore structures. Therefore, the characterization of pore structure is critical to microstructure-performance relationships. A typical pore-size distribution from mercury intrusion porosimeter has a hysteresis loop during an intrusion-extrusion-reintrusion cycle. The hysteresis can be eliminated merely by selecting an appropriately smaller receding contact angle. From this, the total pore-size distribution can be divided into two sub-distributions: one reversible and one irreversible. These sub-distributions probably represent portions of the pore system that are more, or less, accessible, and hence have different effects on the properties. These sub-distributions were found for a series of cement pastes having w/c between 0.32 and 0.60 and ages between 1 and 30 days, nine concrete aggregates, and twenty six building bricks. In addition, physical properties (various densities, non- and evaporable water), mechanical properties (compressive strength and elastic modulus), chloride permeability of cement pastes, and freeze-thaw durability of aggregates and bricks were determined. The sub-distributions were found to have superior correlations with the properties, such as permeability, strength and elastic modulus, and freeze-thaw durability, than did the total pore-size distributions. This new approach to characterize the pore structure may also be equally applicable to other porous materials, and bring new understanding about the microstructure.

Degree

Ph.D.

Advisors

Winslow, Purdue University.

Subject Area

Civil engineering|Materials science

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