Analysis of pore structure, contact angle and pore entrapment of blended cement pastes from mercury porosimetry data

The mercury intrusion porosimetry (MIP) was used to investigate the pore structure characteristics of fly-ash cement pastes with two water to binder ratios (w/b = 0.3, 0.5). The total porosity, pore fraction distribution, contact angle hysteresis and the pore entrapment are quantified from the intrusion/extrusion data. The tortuosity of pore structure is further calculated from pore entrapment. The results show: (1) the w/b ratio is determinant for the formation of pore structure patterns, high w/b ratio providing high porosity, high connectivity but low pore surface roughness to pore structure; (2) the contact angle hysteresis can be related to pore surface roughness, the hysteresis factor αθ attaining respectively 0.42, 0.75 for Paste I (w/b = 0.5) and Paste II (w/b = 0.3) samples at 180 d; (3) the tortuosity and the porosity obey just roughly the power law and more pore characteristics are needed to describe the tortuosity of blended cement pastes.