<![CDATA[ Compressive strength of concrete is one of the most important test for construction properties for quality control of concrete and design new constructions, there are different molds that are used for casting concrete specimen during the concrete works according to various standards at different countries. On the other hand, it is known that different shapes and sizes of concrete specimen can cause differences in the results of compressive strength. In this study the influence of specimen sizes and shapes on compressive strength of normal and high strength concrete are investigated using experimental study. The experimental study was conducted for six different specimen types cube 150 mm, cube 100 mm, cube 75 mm, cylinder Ã150x300 mm, Ã100x200 mm, Ã75x150 mm. At six different concrete strength level was 20,30,40,50,60 and 70 MPa according to standard cube specimen and tested at 28 Days of age. For The experimental study, hardened density, non-destructive tests (Rebound hammer and UPV), compressive strength and splitting tensile strength for different concrete strength level were performed and some analyses were done to obtain conversion factors and some relations between these tests. The results of analyses indicate that for all testing, there is a bigger influence of variation of size and shape of the specimens, by changing the compressive strength level. The compressive strength increases as the specimen size decreases.. Also The compressive strength of cube 150 mm is generally higher than strength cylinder Ã150x300 mm and The conversion factors of compressive strength between is varied from 0.76 to 0.88 for the designed cube compressive strength of 20 to 70 MPa. The conversion factors of compressive strength between standard and non-standard specimen at different concrete strength at 28 days to equivalent 150 mm standard cube specimen had been determined and presented in table 4.7. The correlation between (split tensile test / Schmidt hammer test/ UPV test) of standard specimen 150 x 150 mm cube to compressive strength of non-standard specimen had been determined. Keywords: compressive strength level, influence of specimen sizes and shapes, conversion factors, splitting tensile strength, Schmidt hammer test, UPV. ]]>
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