Control of concrete quality with non-destructive test methods

In this study concrete specimens were prepaired using two different aggregate gradings and four different w/c (water/cement) ratios. Two different aggregate gradings named A16 and B16 were used in the tests. w/c ratios were selected as 0,60 , 0,65 , 0,70 , 0,75. Concrete cylinder and cube specimens were prepaired at the age of 7, 28, 60 and 90 days for each w/c ratio. A total of 32 groups of mixes were prepaired for which 16 group of mixes fitting to A16 grading curve for four different w/c ratios (0,60 , 0,65 , 0,70 and 0,75) and four different ages (7, 28, 60 and 90 days) and, 16 group of mixes fitting to B16 grading curve for four different w/c ratios (0,60 , 0,65 , 0,70 and 0,75) and four different ages (7, 28, 60 and 90 days). Each group consists of eleven specimens namely, four 150 mm standard cubes and seven standard cylinders in dimensions of 150 x 300 mm. Cube and cylinder specimens were cured in the water tank and they were taken from curing tank at the failure age of 7, 28, 60 and 90 days. After UPV and Schmidt hammer measurements on specimens, they were loaded to failure and their failure loads were recorded. Relationships between compressive strengths with UPV, compressive strengths with Schmidt hammer, cylinder splitting strengths with UPV, cylinder splitting strengths with Schmidt hammer were examined, respectively and regression analyses were made. As a results of these analyses regressions equations were obtained for w/c ratio and concrete age, respectively.It is found that the relationships between compressive strengths and cylinder splitting strengths with UPV have more linear behaviour than Schmidt hammer. It is concluded that using UPV and Schmidt hammer methods together is essential for more realistic results.