Yahya Ghasemi Print III pdf

particles in a mixture, 
V
w
is the volume of the water in the mixture, 
V
s
is the volume of all 
particles in a mixture and 
ߙ
௧
is the packing density of a mixture. Research conducted by 
Teichmann (2008) found a good relation between viscosity measurements and excess water 
layer thickness.
The issue with water layer and paste layer theories roots in lack of a comprehensive method to 
measure specific surface area of the particles. Current common methods of measuring the 
specific surface area, including the Blaine test and BET, involve high instrumental complexity 
and are costly. It is also possible to estimate the specific surface area based on the particle size 
distribution curve information and the assumption of spherical shape for the particles. 
However, particle shapes are far from being spherical due to 3D randomness in their shape, 
related to the origin of the aggregates, and production method. This is particularly true for 
crushed aggregate. 
It should be noted that the total surface area of a set of aggregates is chiefly governed by the 
fine aggregate fraction according to square-cube law (Section 3.3.2.1). Assuming that all 
particles were spherical in shape, the surface area can be calculated based on grading curves 
according to the following equation (McCabe et. al., 1993): 
ܽ
௦௣௛
= 6
෍
݉
௜
݀ҧ
௜
.
ߩ
௦
௡
௜ୀଵ
(3.26)
where 
݉
௜
is the mass of a grain fraction 
i
, being the mass percentage of the fraction between 
d
i
and 
d
i+1
.
݀ҧ
௜
is the mean diameter of fraction 
i 
and 
i+1
.
ߩ
௦
is the relative density of the 
particles.
Appended papers III and IV, focus on the possibility of substituting ideal polyhedron shape 
for spheres which can be related to the actual shape of aggregate with better accuracy. The 
details and the method are presented in the following headings: 

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Mix design approaches