Yahya Ghasemi Print III pdf

4.1. Test methods
4.1.1. Sampling of aggregates
It is essential to conduct tests on the aggregates to obtain their physical and mechanical 
properties. Since the aggregates are used in vast quantities in production of concrete; it is of 
great importance to take smaller samples of the aggregate in an appropriate and represented 
way. The method of sampling can cause variations in samples comparing to the pile it was 
taken from such as segregation in large buckets and changes in moisture content in different 
depths of soil. ASTM D75 includes instructions on appropriate sampling depending on how 
and where the samples were taken from e.g. conveyor belt, stockpile etc. In the current study, 
the sampling was done in the laboratory taken from large bags. The samples were taken from 
different depths of the bags to avoid the problems that can occur because of segregation of the 
materials on surface and the base edge. The samples were mixed to produce a composite 
sample before further reducing of the size of the sample.
4.1.2. Sieve analysis
Sieve analysis is defined as the operation of dividing a sample of aggregates into certain 
fractions, each containing of particles of similar size (Neville, 1995). Sieving can be 
conducted in different ways; ASTM C136-14 describes the method for dry sieving of 
aggregates which was used as the method for obtaining the particle size distribution curve 
(PSD) of the materials used in Paper II, however, the test was not designed for accurate 
determination of PSD f
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done either by washing (ASTM C117) or by means of low angle laser light scattering 
technique (LALLS). The LALLS technique was employed for obtaining the sieving curve of 
the powders used in Paper IV.
4.1.3. Specific gravity
Specific gravity of soil solids is the ratio of the mass of a unit volume of a soil solids to the 
mass of the same volume of gas free distilled water at 20°C and should be conducted 
according to the instructions of ASTM D854-14 for soil solids that pass the 4.75 mm sieve by 

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Methods
means of a water Pycnometer. As for the retained soil on the 4.75 mm sieve ASTM C127 
should be utilized. Specific gravity can be measured as absolute or apparent. The absolute 
specific gravity refers to the volume of the solid material excluding all pores while apparent 
specific gravity is calculated to include the impermeable pores but not the capillary ones. The 
latter is commonly used in concrete industry and as an input to particle packing models.