Effect of W/C Ratio and Replacement Materials on Fracture Behavior of Concrete - Via Computed Tomography Method

Nowadays, with the advancements in all fields of science and technology, use new numerical and experimental methods are made possible in the construction industry. X-rays and CT (Computed Tomography) scans are two of the direct methods developed to evaluate the microcracking behavior of concrete. The aim of this study was to evaluate the effect of water/cement ratio and mineral admixtures on microcracking behavior of concrete. For this purpose, total of 12 specimens were produced using three different w/c ratios and four different admixtures. To be able to determine the effects of these differences on both compressive strength and microcracking behavior, first the specimens were subjected to compressive stress loading and then to CT (Computed Tomography) scans to obtain 2D and 3D images. CT (Computed Tomography) scans were taken for different loading levels corresponding the ultimate strength. It was found that out of all specimens, the one containing metakaolin admixture with low w/c ratio has a considerable influence on the microcracking behavior of concrete under compressive stress loading. Although the crack rate of propagation is slow up to 80% of the ultimate stress, cracking accelerates after 80% of loading of metakaolin specimens.