The correlation between porosity and mechanical properties of multicomponent systems consisting of Portland cement-slag-silica fume-metakaolin

Pore structure and mechanical strength of quaternary systems consisting of ordinary Portland cement (PC) replaced in 25, 30 and 35 wt% by ground granulated blast-furnace slag (BFS), silica fume (SF) and metakaolin (MK) were evaluated up to 365 days. Refinement of the structure as a result of cement supplementary materials (SCMs) demonstrated mainly by the rise of gel pores portion, whereas the portion of middle capillary pores decreased. Despite dilution effect in blended samples, both the compressive (CS) and flexural strength (FS) increased throughout all the curing time and reached the values higher than that of referential sample. Development of strength in time reflected different activity of SCMs. The highest values of strength corresponding to the lowest total porosities were determined in the samples containing the most SF (CS = 125 MPa, FS = 18 MPa after 365 days), whilst the highest amount of BFS together with the highest substitution level led to the lowest strengths among blended samples (CS = 99 MPa, FS = 15 MPa).