الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
This research studies the mechanical properties of concrete resulted from recycled concrete aggregate as a replacement ratio from natural aggregate .the source of this recycled aggregate isconcrete tested specimens from faculty of engineering testing laboratory.
Used materials were pink lime stone as natural coarse aggregate, tested specimens of concretewhich crushed and sieved as recycled aggregate , ordinary Portland cement (CEM I 42.5N), natural sand, silica fume, admixture type F and potable water.
The studied factors were the effect of recycled aggregate replacement ratio, cement content, water/cement ratio,adding silica fume, Self-Healing of recycled aggregate and the effect of mixing method.
~ The effect of recycled aggregate replacement ratio was studied at 25%, 50%, 75%, and 100% from coarse aggregate
~ The effect of water / cement ratio was studied at 0.35,0.45 and 0.6.
~ The effect of cement content was studied at 250 kg/m3 and 400 kg/m3
.~ The effect of adding silica fume was studied by’ adding 10% silica fume as a ratio’ from cement content.
~ The effect of self-healing of recycled aggregate was studied by immersing the recycled aggregates in water up to 30 days before using it as recycled aggregate.
~ The effect of mixing method on recycled aggregate concrete . was studied by separating to two stages. The first one is adding 100% of mixing water plus 100% of required cement plus 100 % of recycled aggregates and mix them for 10 minutes. The second one is adding natural aggregate (NA) and sand to complete the mixing process.
Through this research tests were carried out on fresh concrete state and hardened concrete state. These tests were slump,compressive strength,tensile strength ,bond strength, ultrasonic pulse velocity, and porosity (voids ratio) tests.
The conclusions of this study were as follow
• The increase of recycled aggregate percentage, generally, decreases concrete compressive strength, tensile strength, bond strength, and pulse velocity of concrete and increase porosity of concrete compared with concrete without recycled aggregate
• Adding 10% silica fume on recycled aggregate concrete increases concrete compressive strength, tensile strength, bond strength and pulse velocity of recycled
concrete and decrease porosity of recycled concrete compared with recycled concrete without silica fume.
• Adding 10% silica fume on recycled aggregate concrete gives concrete compressive strength higher than concrete without recycled aggregate (natural concrete).
• Self-healed recycled aggregate concrete shows higher compressive strength, tensile strength, bond strength747 and pulse velocity and lower porosity of recycled concrete compared with recycled concrete without self-healed recycled aggregate.
• Self-healed recycled aggregate concrete gives concrete compressive strength higher thJm C£JllC%ete wi.JJlDllt recycled aggregple (rotural. concrete).
• Recycled aggregate concrete made by two stage mixing approach shows higher compressive strength, tensile strength, bond strength and pulse velocity and lower porosity of recycled concrete compared with recycled concrete made by normal mixing approach
• recycled aggregate concrete made by two stage mixing approach gives concrete compressive strength higher than concrete without recycled aggregate (natural concrete).