Reliable　characterization　of　the　pore　structure　is　essentially　important　for　transport-related　durability　studies　of　cementitious　materials.　Mercury　intrusion　porosimetry　has　been　commonly　used　for　pore　structure　measurement　while　the　ink-bottle　effect　significantly　affects　the　trustworthiness　of　pore　size　features　of　cementitious　materials.　Pressurization-depressurization　cycling　mercury　intrusion　porosimetry　(PDC-MIP)　is　an　alternative　approach　previously　reported　with　the　purpose　to　provide　better　estimates　of　pore　size　results.　It　is　found　however　that　the　PDC-MIP　greatly　overestimates　the　ink-bottle　pore　volume　owing　to　the　incomplete　extrusion　of　mercury　in　throat　pores　after　the　pressurization-depressurization　cycle.　Intrusion-extrusion　cyclic　mercury　porosimetry　(IEC-MIP),　as　a　further　improvement,　is　then　described,　which　can　reliably　capture　the　ink-bottle　effect　and　obtain　a　clear　picture　of　the　distribution　of　the　ink-bottle　pores　in　cementitious　materials.　The　ink-bottle　effect　of　cement　pastes　is　observed　being　pore　size-dependent　and　the　role　of　critical　pores　is　emphasized.　Water-cement　ratio　primarily　changes　the　effective　porosity　while　plays　a　minor　role　in　the　ink-bottle　porosity.　The　addition　of　reactive　blends　substantially　enhances　the　ink-bottle　effect　during　mercury　penetration　into　small　pores.　IEC-MIP　tests,　together　with　a　unique　data　analysis,　enable　to　obtain　a　more　truthful　pore　size　distribution.