Experimental investigation on the effect of pressure-filtration method on compressive strength and microstructure of cement paste

•A pressure-filtration method is used to decrease w/c and increase compactness of cement paste.•The relationship between pore size distribution and compact pressure is given.•A model of strength based on compact pressure and pore size distribution is proposed. The paper aims to propose a pressure-filtration method for cement-based materials and investigate its effect on water-cement ratio, porosity, pore size distribution, and compressive strength. A pressure-filtration device is designed to filter out water and compact hardened cement paste with a regular water-cement ratio. Different compact pressure was applied on cement paste, ranging from 0.2 MPa to 2.0 MPa, and the pressure remained constant from the initial setting to the final setting time. The specimens were cured in water at 20 ℃ for 9 days and 28 days before their compressive strength and microstructure were measured. The density of specimens was increased, and the compressive strength was increased by 86% at maximum, with the increment of compact pressure, while the total porosity and the water-cement ratio were decreased. The pressure-filtration method improves compressive strength evidently by reducing the pores larger than 10 nm in diameter, which is found to have a significant impact on strength.