An experimental program was carried out to investigate the relationships between watercementratio (w/c) of concrete specimens and surface air permeability, surface water absorption andmicro-hardness. The relationships are thought to be useful in evaluating the homogeneousness of theconcrete for quality control and investigation purposes. The average values obtained from the surface airpermeability and water drop absorption tests showed a good relationship with w/c although individualpoints are dispersed over a wider range. Even though the dispersion of the measurements is a concern,the averaged values showed that these techniques could be used to compare the water-cement ratio ofhardened concrete of the same type of ingredients. Increased number of measurements is recommendedas a way to increase the accuracy. For Rockwell superficial hardness, the 1.59 mm-diameter indenterdifferentiated the w/c better compared to the 12.5 mm-diameter indenter.
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