الفهرس Only 14 pages are availabe for public view
 |  | from | 202 |  |  |
| | | from | 202 | | |
Abstract
The durability of high strength concrete (HSC) was experimentally
investigated. The evaluation was based on the performance of (HSC) under
three types of mechanical tests (compression, indirect tension and pull-out).
The (BSC) specimens were exposed directly to five different types of
environmental- attack. These include, sulfate, chloride, seawater, air, and
water. The specimens were submerged in three solutions of sodium sulfate of
(5%, 6%, 7%) concentration and sodium chloride of (2%, 3%, 4%)
concentration. The specimens were tested after 28, 360, 540 and 720 days.
The effect of silica fume (SF) addition ratio (0%, 5%, 10%, 15%) by weight
of cement was considered.
The results of this work indicated that the compressive strength of high
strength concrete specimen’s increases with increasing silica fume addition
ratio, also the tensile and bond strengths generally increase, with higher early
age strength and higher early rate of strength gain with time up to about one
year, 15% silica fume concrete shows the greatest improvement in strength.
High strength concrete, incorporating silica fume, when exposed to
sulphate and chloride solutions, exhibits the highest values, higher rates of
increase and the lowest rates of decrease of compressive strength up to 18
months, 10% silica fume addition ratio gives the best results especially at
higher degrees of aggressiveness of the environment.
X -ray diffraction (XRD) patterns of the hardened specimens was
plotted for all cured conditions, which explain the chemical compounds
fanned after hardening and the effect of SF content on these compounds.
The carbonation depth in high strength concrete incorporating SF,
demonstrated by Ph.Ph. test, was diminished. The impermeably of SF
concrete increased with the increase in silica fume content.