Yahya Ghasemi Print III pdf

5.2. Computation of specific surface area
Calculated specific surface areas and their corresponding Blaine values are presented in Table
5.1. and Figure 5.3. where the computations were based on the concept of midsphere and 
arithmetic mean approach. The bold numbers in the following table marks the shape that gives 
closest estimation to the Blaine value. More detailed data on the subject can be found in 
Papers III & IV. 
Table 5.1: Calculated specific surface area of the powders 
Calculation based on Midsphere and Arithmetic mean
Material
Specific surface area (cm
2
/g)
Blaine
CEMIII/B42.5
4500
8011
6543
5664
5433
5215
4625
Marble 4580
5540
4525
3917
3761
3644
3199
Limestone
4040
8936
7300
6319
6064
5812
5160
Quartz 2600
4685
3828
3313
3005
2995
2705

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37
Experimental results
Figure 5.3. Blaine values vs. calculated SSA for different polyhedrons based on Midsphere-arithmetic 
mean assumption. (see Paper IV)
It should also be mentioned that the Blaine test is designed for measuring SSA of cement and 
not necessarily any non-spherical powder, in other words Blaine value is a relative value and 
not absolute for non-cement materials.
In the case of most of the studied powders, the calculated spherical values of SSA were close 
to the Blaine value with some deviation for the particles with less spherical shape (e.g. Marble 
powder). It should be emphasized again that the Blaine value is calculated based on the 
assumption of spherical shape for the particle and so shows better agreement with the 
calculations based on the same assumption, in other words the Blaine value is not 
representative of the actual surface area, Hence to perform a more scientific comparison, the 
specific surface area should be measured by means of a test that produces more realistic 
measure of specific surface area (e.g. Microtomography, see Section 6.3). 
2000
3000
4000
5000
6000
7000
8000
9000
2000
2500
3000
3500
4000
4500
5000
Calculate
d
SSA 
Blaine value 
Tetrahedron
Cube
Octahedron
Dodecahedron
Icosahedron
Sphere
Equality line
Linear (Equality line)
Quartz 
Limeston
e 
CEM
III 
Marb
le

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38
Discussion and conclusions