Wagner turbidimeter

Other methods that have been used to determine specific surface areas of cements include the Wagner turbidimeter (W16) and BET (Brunauer-Emmett-Teller) gas adsorption. The former, as eonventionally used, gives very low results beeause of a false assumption that the mean diameter of the particles smaller than 7.5 pm is 3.8 pm, which is much too high. The BET method gives results two to three times higher than the air permeability... 

Specific surface areas are measured using the nitrogen adsorption method at 77 K, except those marked by ) with the permeation method and ) using the Wagner turbidimeter. 

Wagner Turbidimeter. Apparatus for the determination of the fineness of a powder by measurement of the turbidity, at a specified level and after the lapse of a specified time, of a suspension of particles that are settling by gravity according to Stokes Law. The method was proposed by L. A. Wagner (Proc. ASTM, 33, Pt. 2,553,1933). 

Experimental values obtained by Blaine, using cement and Potters flint, indicated that values obtained by the device described range from 1.5 to almost 2 times those obtained by means of the Wagner (1933) turbidimeter, described in another section of this chapter. 

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