847  EFFECT OF COMPACTION ON ASSESSED CONCRETE STRENGTH SIKIŞTIRMANIN TAHMİN EDİLEN BETON DAYANIMI ÜZERİNDEKİ ETKİSİ Mustafa TUNCAN 1 , Ömer ARIÖZ 1 , Kambiz RAMYAR 2 , Bekir KARASU 3 , Ahmet TUNCAN 1 ve Kadir KILINÇ 1 1 Anadolu University, Faculty of Engineering and Architecture, Department of Civil Engineering, Eskisehir 2 Ege University, Faculty of Engineering and Architecture, Department of Civil Engineering, İzmir 3 Anadolu University, Faculty of Engineering and Architecture, Department of Materials Science and Engineering, Eskisehir ABSTRACT The compressive strength of concrete cast in structures is generally determined by standard cube or cylinder tests. However, these standard tests on specimens represent the potential quality of concrete and they should include full compaction. On the other hand, compaction received by concrete structures and standard specimens may be different. The strength of moist-cured concrete mainly depends on the water-to-cement ratio and degree of compaction. The presence of voids in concrete due to improper compaction significantly reduces the strength. In this experimental investigation, the effect of compaction on concrete strength assessed by rebound hammer, ultrasonic pulse velocity, and pull-out techniques as well as core test were examined. For this purpose, a concrete mixture was prepared by ordinary Portland cement, crushed limestone aggregate, water, and a plasticizing admixture. The cubes and beams were cast by the prepared mixture. Beams were compacted in three different levels. The results have shown that the rebound number, ultrasonic pulse velocity, pull-out force, and core strength were significantly affected by the level of compaction. Keywords: Concrete, Compaction, Testing, Strength.