الفهرس 
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Abstract
Durability of (;oncrete refers to its ability to endure weathering action, attack by various chemical substances and many other conditions to which it may be exposed over the years. This thesis considers many factors which affecting the durability of concrete. To achieve this goal the experimental program was considered the following factors:
1- Three types of cement (CEM I, SRPC sulfate resistance portland cement and
TYPE II modified cement).
2- Three cement contents (350, 450 and 500 kg/m\ 3- Three water-cement ratios (0.35, 004 and 0045).
4- Three percentage of silica fume as a replacement of cement content (0, 5 and 10%).
5- Three percentage of sodium chloride (0, I and 2%) of cement content.
To study the effect of these factors on the durability and properties of concrete, the following tests were performed:
1- Compression test.
2- Tensile strength.
3- Flexural strength.
4- Chloride ion diffusion test. 5- Oxygen permeability test. 6- Accelerated corrosion test.
The fractional factorial method of the experimentation was followed for the organization of the experiments and analysis of the results.
According to the fractional factorial method 27 mixes were selected to consider the effect of all factors on experiments.
The analysis of variance (ANOV A) table was performed on the results obtained to check the significance of each factor. The main advantages of this method are as follow it measures the interaction between factors, which cannot be
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achieved by classical methods of experimentation and it provides a statistically mathematical approach for the analysis of the results at a latter stage .
The results show that the increasing of cement content leads to improve the mechanical vrcperties of concrete and improves the concrete resistance of chloride ion diffusion, oxygen permeability and reinforcing steel corrosion.
Also increasing the water-cement ratio reduces the mechanical properties of concrete and increases the permeability of concrete that it leads to increases the chloride ion diffusion, oxygen permeability and reinforcing steel corrosion.
The presence of silica fume has an advantage effect on the mechanical properties of concrete and enhances the durability properties of concrete, therewith the addition of 10% silica fume as a replacement of cement content improves the properties of concrete and its resistance more than 5% silica fume.
The addition of sodium chloride that it may be included in aggregate and water increases the compressive strength up to 28-days but it has an adverse effect at later ages, but it has an insignificant effect on tensile and flexural strength. The presence of sodium chloride leads to reduce the resistance of chloride ion diffusion, oxygen permeability and the major adverse effect is on the reinforcing steel corrosion.