Chloride migration coefficient

The measured chloride migration coefficients (NT Build 492) of drilled cores from small blocks are shown below.

At 28 days maturity there seems to be a clear trend that the slag based concretes have the lowest chloride migration coefficients of the tested concrete compositions. Likewise, 3-powder compositions (cement, fly ash silica fume) have lower coefficients than pure Portland cement mixtures, while fly ash concrete has the highest chloride migration coefficient.

The ranking of the concretes is much different when the chloride migration coefficient is measured after 180 maturity days. Here pure Portland cement concrete (A) has the highest migration coefficient followed by microsilica concrete (E,O), fly ash concrete and 3-powder concrete at about the same level, and slag based concrete with the lowest coefficients.