Tracing mercury entrapment in porous cement paste after mercury intrusion test by X-ray computed tomography and implications for pore structure characterization

Highlights: • A post-MIP X-CT testing scheme was developed; • Maximum intrusion pressure and surface conformance were considered in the MIP tests; • Surface conformance can depress the first rise of MIP and narrow the threshold pore size; • X-CT can trace the entrapped and released mercury drops; • The findings of this study provide insights in pore structure characterization. -- Abstract: Mercury entrapment in a porous material after mercury intrusion porosimetry (MIP) test is widely reported, yet the characterization of the entrapped mercury remains unclear. This study reported an experimental investigation on the entrapped mercury in a porous cement paste with/without surface-conformance control determined by X-ray computed tomography (X-CT). MIP tests were performed under three different maximum intrusion pressures. Results show that the surface-conformance control can substantially depress the first rise of throat size distributions and lower the threshold throat sizes. The entrapped mercury drops can be easily traced by X-CT due to the high mass attenuation coefficient of mercury. Both the entrapped and released mercury drops only occupy the limited volume fraction of the intruded pores. The surface conformance can decrease the mercury volume released from the pores. The findings of this study provide insights in better pore structure characterization of porous cement-based materials.