Yahya Ghasemi Print III pdf

1.2. Research Objectives and Questions
According to above, the main objective of the project is to formulate an approach to mix 
design where the workability of the fresh concrete can be anticipated before actual mixing 
takes place. The mix design method may be based on principles of particle packing and water 
layer theory. Water demand, shape of aggregates and changes in size distribution curve, will 
be studied as the mentioned parameters can greatly influence the properties of concrete in 
fresh state.
The research is expected to answer the following questions:
1- Is it possible to formulate a simple yet efficient mix design approach?
2- Can optimizing concrete constitutes lead to a greener less pollutant production of concrete? 
3- What is the role and significance of water demand in workability of fresh concrete?

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4 
Introduction
4- What are the main parameters that results in aggregate from one quarry to have different 
performance properties comparing to another quarry? (shape, flakiness, size distribution 
curve, mineralogy etc.)
1.3. Limitations
The studies were restricted by various limitations which bounds the scope of this document:
Firstly, the vast domain of interconnected parameters that affect the properties of fresh 
concrete makes it difficult to isolate and study each parameter without considering the 
possible effect of changes in other constitutes in concrete. 
Secondly, it should be mentioned that all of the packing studies conducted were only based on 
loose packing method and does not include other packing methods such as hard packing and
vibration compacted packing. Moreover, the used materials were taken from a limited number 
of Swedish quarries. 
Thirdly, the complexity and the randomness in properties of aggregates such as shape, surface 
texture, size distribution curve, chemical components, etc. makes it almost impossible to 
simulate their flow in fresh concrete.
Fourth, this document only deals with the role of aggregates in mix design as a part of the 
overall research planned for completion of the PhD and does not include tests on concrete at 
this stage.
Finally, the complexity and the high cost of conducting accurate specific surface 
measurements limit the number of samples that can be tested.