Effect of self-desiccation on the pore structure of paste and mortar incorporating 70% GGBS

•GGBS refines pores and creates a distribution peak for pore range within 10 nm.•GGBS tends to increase substantially the pore entrapment for MIP.•Archie’s law is just roughly obeyed by GGBS incorporated materials.•Pore self-desiccation is enhanced by low w/b and sealed curing.•Self-desiccation percolates pores at μm level but densifies CSH at nm level.

This paper investigates the pore structure of cement-based materials with/without 70% ground granulated blastfurnace slag (GGBS). The emphasis is put on the effect of self-desiccation. Pore characterization parameters include total porosity, specific surface area (SSA), pore size distribution (PSD), pore entrapment and surface fractal dimension. The results show: (1) pore refinement by GGBS is evident and GGBS increases substantially the SSA and fractal dimension values; (2) the pore refinement moves pore distribution from the range of 10 nm–100 nm to that of <<10 nm; (3) the self-desiccation under sealed-curing creates a PSD peak in the range of >>100 nm and compacts the nanostructure of hydrates.