Moisture and ionic transport in concretes containing coarse limestone powder

Concretes containing a coarse limestone powder (median particle size of 72 μm) as a partial cement replacement material are proportioned so as to attain similar 7-day compressive strengths as a 0.40 water-to-cement ratio (w/c) control concrete. The moisture and chloride ion transport behavior of the concretes containing limestone powder with and without small amounts of silica fume are evaluated in this paper. It is shown that a 15% cement replacement with coarse limestone powder at a water-to-powder ratio (w/p) of 0.34 results in concretes of better or comparable compressive strengths, porosities, moisture transport parameters (overall moisture intake, and sorptivity), and rapid chloride permeability (RCP) as that of a 0.37 w/c plain concrete. However, the non-steady state migration coefficients (Dnssm) of concretes containing limestone powder are found to be higher than those of plain concretes of even higher w/c. A microstructural parameter (ϕβ – product of porosity and pore connectivity) is used to relate the pore structure to the moisture and ionic transport. Relationships between ϕβ and the moisture and ionic transport parameters are provided, which shed light on the combined influence of w/p and a highly reactive cement replacement material such as silica fume on the different transport properties of concretes containing a coarse limestone powder.