الفهرس 
Chapter (1): IntroductionOnly 14 pages are availabe for public view
 |  | from | 173 |  |  |
| | | from | 173 | | |
Abstract
Sulfates in fine aggregate are a major problem when it exists in excessive
amount especially in the Middle East. Most of sulfate salts in fine
aggregate are composed of calcium, magnesium, potassium and sodium
sulfates. Calcium sulfates is the most common salt present in fine
aggregate. It is usually finding as gypsum. It is difficult to obtain the
specific sulfates content in fine aggregate within standard specifications.
Most of samples of sand was refused because the finding of sulfates. This
research was conducted to investigate the effect of adding different
contents of gypsum to fine aggregate as a replacement by weight on some
properties of two types of concrete self-compacting concrete( SCC) and
high strength concrete(HSC) even accept more samples. In these work
three bases mixes of each type of concrete are used: mixes with different
contents of metakaolin, mixes with different contents of gypsum and mixes
incorporating different contents of metakaolin and gypsum. This study is
devoted to determine the allowable content of sulfates in fine aggregate.
Three levels of gypsum were tested (0.5, 1, 1.5) % by weight of fine
aggregate as a replacement and three levels of metakaolin were tested (5,
10, 15) % by the weight of cement as a replacement. The experimental
program is devoted to produce concrete with different levels of metakaolin
and gypsum and determine its mechanical properties such as compressive
strength, splitting tensile strength, modulus of elasticity and flexural
strength. The tests results arrived from this work show that the optimum
gypsum content was 1.5% by weight of fine aggregates for mixes of SCC
which gives increased in compressive strength and tensile strength, and
1.5% gypsum for mixes of HSC which increased the compressive strength
and 1% gypsum which increased the splitting tensile strength . Results also
showed that the mixes which contain 5% MK and 1% gypsum is the best
mix for SCC, and mix of 10% MK and 0.5% gypsum is the best mix for
HSC. In this study also two beams were mixed as the bests mixes of SCC
and HSC and their results emphasized high ductility and energy absorption
properties which are very use-ful for dynamic applications. The energy
absorption of beam HSC is1.53 times that of beam SCC. There is no
spalling of concrete cover of the tested beams at failure, this is
predominant. The developed cracks at failure were fine crack widths
resulting from employing the proper designed mix.