Figure 3: Effect of curing and Lytag volume fraction on oxygen permeability (65% RH at 30°C; W/C=0.39) Figure 4: Effect of W/C and coarse aggregate type (volume fraction=0.42 in concrete) on oxygen permeability (65% RH at 30°C; sealed curing)

For sealed curing, lightweight concretes are much less permeable than equivalent mortar and normal weight concrete (Fig. 2 and 3). For both curing regimes, the data show that an Increase in the aggregate volume fraction in the range 32-52% does not necessarily Increase oxygen permeability (Fig. 3). A change of the curing regime from 100% RH to sealed curing is found to result in about two and four fold Increases in oxygen permeability for basalt concrete and mortar respectively. A relatively smaller effect of the curing regime is observed with both Lytag mixes with a coarse aggregate volume fraction of 42%. Whereas in the Lytag (L2.ar) mixes with a coarse aggregate volume fraction of 32 and 52% and the Pellite concrete, the type of curing had no significant effect.