Nearly all concrete properties - epecially durabilty - are influenced by the porosity and the pore size distribution of the cement paste. Both parameters are influenced by different main constitents in a different manner. Figure 1 shows the influence of cements containing limestone (LL), fly ash (V), silica fume (D) and ground granulated blastfurnce slag (S) on the total porosity and the pore size distribution of cement paste compared to cement paste with Portland cement.

Figure 1:Influence of cements containing limestone (LL), fly ash (V), silica fume (D) and ground granulated blastfurnce slag (S) on the total porosity and the pore size distribution of cement paste compared to cement paste with Portland cement. Data: [Mül05, Sch98] Compiled by Christoph Müller, VDZ

Whereas higher amounts of limestone meal can lead to a higher porosity and especially to a higher amount of capillary pores > 0,1 m, the use of blended cements containing silica fume or higher amounts of fly ash or ground granulated blastfurnace slag causes an increase of fine pores and a decrease of capillary pores resulting in a hiher density of the concrete containing these blended cements (Figure 1).

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