الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
1- causes which had led to reinforcing steel rusting in the Faculty of Medicine building are:-
~ste. This is due to the high solubility of magnesium sulfates. The presence of several aggressive agents like ~gnesium, oxygen, carbon dioxide, calcium, ammonium, a~ sodium is led to accelarate steel corrosion.
* The observed deterioration is characterized by concrete expansion and cracking. This takes place when the reactive aluminate present in sufficient quantities in cement used is attacked by sulfate ions of calcium, forming calcium sulfoaluminate hydrate, leading to concrete deterioration. The reaction between sulfates and the leaching out of cement produces insoluble salts. These salts are larger in volume than the compounds they replace. The end products of the reaction thus lead to progressive cracking and spalling of concrete. This has ~d to exposing the steel to the air and consequently ~s led to the reinforcing steel corrosion.
* The relatively low amount of cement which was Qsed in the concrete mixes has led to low quality concrete and hence the effect of the chlorides was accelerated, as the steel protection was not adequate. ~e reduction of the alkalinity of concrete was due to the presence of chlorides, carbonation and the small ~ount of cement used in co~crete mix. This has led to the rplnforcing steel rusti 9 and to the formation
of oxides and hydroxides which have a volume much greater than the volume of the original metallic iron. This increase in volume has caused high radial bursting stresses around reinforcing bars and resulted in local radial cracks. These splitting cracks can propagate along the bar, resulting in the formation of longit udinal cracks or spalling the concrete, then the oxygen and the moisture can penetrate to the steel causing the steel corrosion to continue.
* On the other hand, considerable amount of modifications and corrective work were carried out on that building as its use was aodifi~d. Many parts of the original building were demolished to suit the required needs where demolition of concrete was carried out by Enual hammering. This may have caused in the appearance and propagation of cracks, and hence helped in the corrosion process. Water leakage from the plumping work .•.. ; .’l1~-’{J one -of the factors that has caused acceleration of steel corrosion in that building.
* The small amount of concrete cover thickness ~ich was obs~rved in all the structaral elements in H:.-1.1.o bu i ld i ng can also be regarded as one of the factors that has caused such corrosion.
2- It is approved that the amount of chemical rust
at a certain time mainly depends on the cement content
in the mix, the percentage of chloride ions and sulphate
ions, water cement ratio of mix, the aiameter of embbeded
~rs in concrete media as well as some other factors.
The role of the effect of each factor can be deduced on
the 1 ight of the following recommended re lation:
230
R 0= K X log\: X (logT) X 1/ (W/C) X (l/C) X (2- D) .
28 0
where:
= % the amount of rust at a certain time chemically.
f = cube strength of concrete after 28 days in
Kg/cm ..... 2
C = cement content 18 K9/aA3
T = test time in days
D = diameter of used bar in this test (13mm.)
lln
= 2.5*10 ..... ’ in this work.
it depends on the ~ of chloride ions and the % of sulfate ions in the aggregate used 1n concrete.
3- Addition of commercial lime to a given concrete
affects the amount of rust of steel considerably
in these mixes. Again the
the percentage of added lime.